// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) /* * Common eBPF ELF object loading operations. * * Copyright (C) 2013-2015 Alexei Starovoitov * Copyright (C) 2015 Wang Nan * Copyright (C) 2015 Huawei Inc. * Copyright (C) 2017 Nicira, Inc. * Copyright (C) 2019 Isovalent, Inc. */ #ifndef _GNU_SOURCE #define _GNU_SOURCE #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "libbpf.h" #include "bpf.h" #include "btf.h" #include "str_error.h" #include "libbpf_internal.h" #include "hashmap.h" #ifndef BPF_FS_MAGIC #define BPF_FS_MAGIC 0xcafe4a11 #endif #define BPF_INSN_SZ (sizeof(struct bpf_insn)) /* vsprintf() in __base_pr() uses nonliteral format string. It may break * compilation if user enables corresponding warning. Disable it explicitly. */ #pragma GCC diagnostic ignored "-Wformat-nonliteral" #define __printf(a, b) __attribute__((format(printf, a, b))) static struct bpf_map *bpf_object__add_map(struct bpf_object *obj); static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog); static int __base_pr(enum libbpf_print_level level, const char *format, va_list args) { if (level == LIBBPF_DEBUG) return 0; return vfprintf(stderr, format, args); } static libbpf_print_fn_t __libbpf_pr = __base_pr; libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn) { libbpf_print_fn_t old_print_fn = __libbpf_pr; __libbpf_pr = fn; return old_print_fn; } __printf(2, 3) void libbpf_print(enum libbpf_print_level level, const char *format, ...) { va_list args; if (!__libbpf_pr) return; va_start(args, format); __libbpf_pr(level, format, args); va_end(args); } static void pr_perm_msg(int err) { struct rlimit limit; char buf[100]; if (err != -EPERM || geteuid() != 0) return; err = getrlimit(RLIMIT_MEMLOCK, &limit); if (err) return; if (limit.rlim_cur == RLIM_INFINITY) return; if (limit.rlim_cur < 1024) snprintf(buf, sizeof(buf), "%zu bytes", (size_t)limit.rlim_cur); else if (limit.rlim_cur < 1024*1024) snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024); else snprintf(buf, sizeof(buf), "%.1f MiB", (double)limit.rlim_cur / (1024*1024)); pr_warn("permission error while running as root; try raising 'ulimit -l'? current value: %s\n", buf); } #define STRERR_BUFSIZE 128 /* Copied from tools/perf/util/util.h */ #ifndef zfree # define zfree(ptr) ({ free(*ptr); *ptr = NULL; }) #endif #ifndef zclose # define zclose(fd) ({ \ int ___err = 0; \ if ((fd) >= 0) \ ___err = close((fd)); \ fd = -1; \ ___err; }) #endif static inline __u64 ptr_to_u64(const void *ptr) { return (__u64) (unsigned long) ptr; } enum kern_feature_id { /* v4.14: kernel support for program & map names. */ FEAT_PROG_NAME, /* v5.2: kernel support for global data sections. */ FEAT_GLOBAL_DATA, /* BTF support */ FEAT_BTF, /* BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO support */ FEAT_BTF_FUNC, /* BTF_KIND_VAR and BTF_KIND_DATASEC support */ FEAT_BTF_DATASEC, /* BTF_FUNC_GLOBAL is supported */ FEAT_BTF_GLOBAL_FUNC, /* BPF_F_MMAPABLE is supported for arrays */ FEAT_ARRAY_MMAP, /* kernel support for expected_attach_type in BPF_PROG_LOAD */ FEAT_EXP_ATTACH_TYPE, /* bpf_probe_read_{kernel,user}[_str] helpers */ FEAT_PROBE_READ_KERN, /* BPF_PROG_BIND_MAP is supported */ FEAT_PROG_BIND_MAP, /* Kernel support for module BTFs */ FEAT_MODULE_BTF, /* BTF_KIND_FLOAT support */ FEAT_BTF_FLOAT, __FEAT_CNT, }; static bool kernel_supports(enum kern_feature_id feat_id); enum reloc_type { RELO_LD64, RELO_CALL, RELO_DATA, RELO_EXTERN_VAR, RELO_EXTERN_FUNC, RELO_SUBPROG_ADDR, }; struct reloc_desc { enum reloc_type type; int insn_idx; int map_idx; int sym_off; }; struct bpf_sec_def; typedef struct bpf_link *(*attach_fn_t)(const struct bpf_sec_def *sec, struct bpf_program *prog); struct bpf_sec_def { const char *sec; size_t len; enum bpf_prog_type prog_type; enum bpf_attach_type expected_attach_type; bool is_exp_attach_type_optional; bool is_attachable; bool is_attach_btf; bool is_sleepable; attach_fn_t attach_fn; }; /* * bpf_prog should be a better name but it has been used in * linux/filter.h. */ struct bpf_program { const struct bpf_sec_def *sec_def; char *sec_name; size_t sec_idx; /* this program's instruction offset (in number of instructions) * within its containing ELF section */ size_t sec_insn_off; /* number of original instructions in ELF section belonging to this * program, not taking into account subprogram instructions possible * appended later during relocation */ size_t sec_insn_cnt; /* Offset (in number of instructions) of the start of instruction * belonging to this BPF program within its containing main BPF * program. For the entry-point (main) BPF program, this is always * zero. For a sub-program, this gets reset before each of main BPF * programs are processed and relocated and is used to determined * whether sub-program was already appended to the main program, and * if yes, at which instruction offset. */ size_t sub_insn_off; char *name; /* sec_name with / replaced by _; makes recursive pinning * in bpf_object__pin_programs easier */ char *pin_name; /* instructions that belong to BPF program; insns[0] is located at * sec_insn_off instruction within its ELF section in ELF file, so * when mapping ELF file instruction index to the local instruction, * one needs to subtract sec_insn_off; and vice versa. */ struct bpf_insn *insns; /* actual number of instruction in this BPF program's image; for * entry-point BPF programs this includes the size of main program * itself plus all the used sub-programs, appended at the end */ size_t insns_cnt; struct reloc_desc *reloc_desc; int nr_reloc; int log_level; struct { int nr; int *fds; } instances; bpf_program_prep_t preprocessor; struct bpf_object *obj; void *priv; bpf_program_clear_priv_t clear_priv; bool load; bool mark_btf_static; enum bpf_prog_type type; enum bpf_attach_type expected_attach_type; int prog_ifindex; __u32 attach_btf_obj_fd; __u32 attach_btf_id; __u32 attach_prog_fd; void *func_info; __u32 func_info_rec_size; __u32 func_info_cnt; void *line_info; __u32 line_info_rec_size; __u32 line_info_cnt; __u32 prog_flags; }; struct bpf_struct_ops { const char *tname; const struct btf_type *type; struct bpf_program **progs; __u32 *kern_func_off; /* e.g. struct tcp_congestion_ops in bpf_prog's btf format */ void *data; /* e.g. struct bpf_struct_ops_tcp_congestion_ops in * btf_vmlinux's format. * struct bpf_struct_ops_tcp_congestion_ops { * [... some other kernel fields ...] * struct tcp_congestion_ops data; * } * kern_vdata-size == sizeof(struct bpf_struct_ops_tcp_congestion_ops) * bpf_map__init_kern_struct_ops() will populate the "kern_vdata" * from "data". */ void *kern_vdata; __u32 type_id; }; #define DATA_SEC ".data" #define BSS_SEC ".bss" #define RODATA_SEC ".rodata" #define KCONFIG_SEC ".kconfig" #define KSYMS_SEC ".ksyms" #define STRUCT_OPS_SEC ".struct_ops" enum libbpf_map_type { LIBBPF_MAP_UNSPEC, LIBBPF_MAP_DATA, LIBBPF_MAP_BSS, LIBBPF_MAP_RODATA, LIBBPF_MAP_KCONFIG, }; static const char * const libbpf_type_to_btf_name[] = { [LIBBPF_MAP_DATA] = DATA_SEC, [LIBBPF_MAP_BSS] = BSS_SEC, [LIBBPF_MAP_RODATA] = RODATA_SEC, [LIBBPF_MAP_KCONFIG] = KCONFIG_SEC, }; struct bpf_map { char *name; int fd; int sec_idx; size_t sec_offset; int map_ifindex; int inner_map_fd; struct bpf_map_def def; __u32 numa_node; __u32 btf_var_idx; __u32 btf_key_type_id; __u32 btf_value_type_id; __u32 btf_vmlinux_value_type_id; void *priv; bpf_map_clear_priv_t clear_priv; enum libbpf_map_type libbpf_type; void *mmaped; struct bpf_struct_ops *st_ops; struct bpf_map *inner_map; void **init_slots; int init_slots_sz; char *pin_path; bool pinned; bool reused; }; enum extern_type { EXT_UNKNOWN, EXT_KCFG, EXT_KSYM, }; enum kcfg_type { KCFG_UNKNOWN, KCFG_CHAR, KCFG_BOOL, KCFG_INT, KCFG_TRISTATE, KCFG_CHAR_ARR, }; struct extern_desc { enum extern_type type; int sym_idx; int btf_id; int sec_btf_id; const char *name; bool is_set; bool is_weak; union { struct { enum kcfg_type type; int sz; int align; int data_off; bool is_signed; } kcfg; struct { unsigned long long addr; /* target btf_id of the corresponding kernel var. */ int kernel_btf_obj_fd; int kernel_btf_id; /* local btf_id of the ksym extern's type. */ __u32 type_id; } ksym; }; }; static LIST_HEAD(bpf_objects_list); struct module_btf { struct btf *btf; char *name; __u32 id; int fd; }; struct bpf_object { char name[BPF_OBJ_NAME_LEN]; char license[64]; __u32 kern_version; struct bpf_program *programs; size_t nr_programs; struct bpf_map *maps; size_t nr_maps; size_t maps_cap; char *kconfig; struct extern_desc *externs; int nr_extern; int kconfig_map_idx; int rodata_map_idx; bool loaded; bool has_subcalls; /* * Information when doing elf related work. Only valid if fd * is valid. */ struct { int fd; const void *obj_buf; size_t obj_buf_sz; Elf *elf; GElf_Ehdr ehdr; Elf_Data *symbols; Elf_Data *data; Elf_Data *rodata; Elf_Data *bss; Elf_Data *st_ops_data; size_t shstrndx; /* section index for section name strings */ size_t strtabidx; struct { GElf_Shdr shdr; Elf_Data *data; } *reloc_sects; int nr_reloc_sects; int maps_shndx; int btf_maps_shndx; __u32 btf_maps_sec_btf_id; int text_shndx; int symbols_shndx; int data_shndx; int rodata_shndx; int bss_shndx; int st_ops_shndx; } efile; /* * All loaded bpf_object is linked in a list, which is * hidden to caller. bpf_objects__ handlers deal with * all objects. */ struct list_head list; struct btf *btf; struct btf_ext *btf_ext; /* Parse and load BTF vmlinux if any of the programs in the object need * it at load time. */ struct btf *btf_vmlinux; /* vmlinux BTF override for CO-RE relocations */ struct btf *btf_vmlinux_override; /* Lazily initialized kernel module BTFs */ struct module_btf *btf_modules; bool btf_modules_loaded; size_t btf_module_cnt; size_t btf_module_cap; void *priv; bpf_object_clear_priv_t clear_priv; char path[]; }; #define obj_elf_valid(o) ((o)->efile.elf) static const char *elf_sym_str(const struct bpf_object *obj, size_t off); static const char *elf_sec_str(const struct bpf_object *obj, size_t off); static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx); static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name); static int elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn, GElf_Shdr *hdr); static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn); static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn); void bpf_program__unload(struct bpf_program *prog) { int i; if (!prog) return; /* * If the object is opened but the program was never loaded, * it is possible that prog->instances.nr == -1. */ if (prog->instances.nr > 0) { for (i = 0; i < prog->instances.nr; i++) zclose(prog->instances.fds[i]); } else if (prog->instances.nr != -1) { pr_warn("Internal error: instances.nr is %d\n", prog->instances.nr); } prog->instances.nr = -1; zfree(&prog->instances.fds); zfree(&prog->func_info); zfree(&prog->line_info); } static void bpf_program__exit(struct bpf_program *prog) { if (!prog) return; if (prog->clear_priv) prog->clear_priv(prog, prog->priv); prog->priv = NULL; prog->clear_priv = NULL; bpf_program__unload(prog); zfree(&prog->name); zfree(&prog->sec_name); zfree(&prog->pin_name); zfree(&prog->insns); zfree(&prog->reloc_desc); prog->nr_reloc = 0; prog->insns_cnt = 0; prog->sec_idx = -1; } static char *__bpf_program__pin_name(struct bpf_program *prog) { char *name, *p; name = p = strdup(prog->sec_name); while ((p = strchr(p, '/'))) *p = '_'; return name; } static bool insn_is_subprog_call(const struct bpf_insn *insn) { return BPF_CLASS(insn->code) == BPF_JMP && BPF_OP(insn->code) == BPF_CALL && BPF_SRC(insn->code) == BPF_K && insn->src_reg == BPF_PSEUDO_CALL && insn->dst_reg == 0 && insn->off == 0; } static bool is_ldimm64_insn(struct bpf_insn *insn) { return insn->code == (BPF_LD | BPF_IMM | BPF_DW); } static bool is_call_insn(const struct bpf_insn *insn) { return insn->code == (BPF_JMP | BPF_CALL); } static bool insn_is_pseudo_func(struct bpf_insn *insn) { return is_ldimm64_insn(insn) && insn->src_reg == BPF_PSEUDO_FUNC; } static int bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog, const char *name, size_t sec_idx, const char *sec_name, size_t sec_off, void *insn_data, size_t insn_data_sz) { if (insn_data_sz == 0 || insn_data_sz % BPF_INSN_SZ || sec_off % BPF_INSN_SZ) { pr_warn("sec '%s': corrupted program '%s', offset %zu, size %zu\n", sec_name, name, sec_off, insn_data_sz); return -EINVAL; } memset(prog, 0, sizeof(*prog)); prog->obj = obj; prog->sec_idx = sec_idx; prog->sec_insn_off = sec_off / BPF_INSN_SZ; prog->sec_insn_cnt = insn_data_sz / BPF_INSN_SZ; /* insns_cnt can later be increased by appending used subprograms */ prog->insns_cnt = prog->sec_insn_cnt; prog->type = BPF_PROG_TYPE_UNSPEC; prog->load = true; prog->instances.fds = NULL; prog->instances.nr = -1; prog->sec_name = strdup(sec_name); if (!prog->sec_name) goto errout; prog->name = strdup(name); if (!prog->name) goto errout; prog->pin_name = __bpf_program__pin_name(prog); if (!prog->pin_name) goto errout; prog->insns = malloc(insn_data_sz); if (!prog->insns) goto errout; memcpy(prog->insns, insn_data, insn_data_sz); return 0; errout: pr_warn("sec '%s': failed to allocate memory for prog '%s'\n", sec_name, name); bpf_program__exit(prog); return -ENOMEM; } static int bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data, const char *sec_name, int sec_idx) { Elf_Data *symbols = obj->efile.symbols; struct bpf_program *prog, *progs; void *data = sec_data->d_buf; size_t sec_sz = sec_data->d_size, sec_off, prog_sz, nr_syms; int nr_progs, err, i; const char *name; GElf_Sym sym; progs = obj->programs; nr_progs = obj->nr_programs; nr_syms = symbols->d_size / sizeof(GElf_Sym); sec_off = 0; for (i = 0; i < nr_syms; i++) { if (!gelf_getsym(symbols, i, &sym)) continue; if (sym.st_shndx != sec_idx) continue; if (GELF_ST_TYPE(sym.st_info) != STT_FUNC) continue; prog_sz = sym.st_size; sec_off = sym.st_value; name = elf_sym_str(obj, sym.st_name); if (!name) { pr_warn("sec '%s': failed to get symbol name for offset %zu\n", sec_name, sec_off); return -LIBBPF_ERRNO__FORMAT; } if (sec_off + prog_sz > sec_sz) { pr_warn("sec '%s': program at offset %zu crosses section boundary\n", sec_name, sec_off); return -LIBBPF_ERRNO__FORMAT; } pr_debug("sec '%s': found program '%s' at insn offset %zu (%zu bytes), code size %zu insns (%zu bytes)\n", sec_name, name, sec_off / BPF_INSN_SZ, sec_off, prog_sz / BPF_INSN_SZ, prog_sz); progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(*progs)); if (!progs) { /* * In this case the original obj->programs * is still valid, so don't need special treat for * bpf_close_object(). */ pr_warn("sec '%s': failed to alloc memory for new program '%s'\n", sec_name, name); return -ENOMEM; } obj->programs = progs; prog = &progs[nr_progs]; err = bpf_object__init_prog(obj, prog, name, sec_idx, sec_name, sec_off, data + sec_off, prog_sz); if (err) return err; /* if function is a global/weak symbol, but has hidden * visibility (STV_HIDDEN), mark its BTF FUNC as static to * enable more permissive BPF verification mode with more * outside context available to BPF verifier */ if (GELF_ST_BIND(sym.st_info) != STB_LOCAL && GELF_ST_VISIBILITY(sym.st_other) == STV_HIDDEN) prog->mark_btf_static = true; nr_progs++; obj->nr_programs = nr_progs; } return 0; } static __u32 get_kernel_version(void) { __u32 major, minor, patch; struct utsname info; uname(&info); if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3) return 0; return KERNEL_VERSION(major, minor, patch); } static const struct btf_member * find_member_by_offset(const struct btf_type *t, __u32 bit_offset) { struct btf_member *m; int i; for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) { if (btf_member_bit_offset(t, i) == bit_offset) return m; } return NULL; } static const struct btf_member * find_member_by_name(const struct btf *btf, const struct btf_type *t, const char *name) { struct btf_member *m; int i; for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) { if (!strcmp(btf__name_by_offset(btf, m->name_off), name)) return m; } return NULL; } #define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_" static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix, const char *name, __u32 kind); static int find_struct_ops_kern_types(const struct btf *btf, const char *tname, const struct btf_type **type, __u32 *type_id, const struct btf_type **vtype, __u32 *vtype_id, const struct btf_member **data_member) { const struct btf_type *kern_type, *kern_vtype; const struct btf_member *kern_data_member; __s32 kern_vtype_id, kern_type_id; __u32 i; kern_type_id = btf__find_by_name_kind(btf, tname, BTF_KIND_STRUCT); if (kern_type_id < 0) { pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n", tname); return kern_type_id; } kern_type = btf__type_by_id(btf, kern_type_id); /* Find the corresponding "map_value" type that will be used * in map_update(BPF_MAP_TYPE_STRUCT_OPS). For example, * find "struct bpf_struct_ops_tcp_congestion_ops" from the * btf_vmlinux. */ kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX, tname, BTF_KIND_STRUCT); if (kern_vtype_id < 0) { pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n", STRUCT_OPS_VALUE_PREFIX, tname); return kern_vtype_id; } kern_vtype = btf__type_by_id(btf, kern_vtype_id); /* Find "struct tcp_congestion_ops" from * struct bpf_struct_ops_tcp_congestion_ops { * [ ... ] * struct tcp_congestion_ops data; * } */ kern_data_member = btf_members(kern_vtype); for (i = 0; i < btf_vlen(kern_vtype); i++, kern_data_member++) { if (kern_data_member->type == kern_type_id) break; } if (i == btf_vlen(kern_vtype)) { pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n", tname, STRUCT_OPS_VALUE_PREFIX, tname); return -EINVAL; } *type = kern_type; *type_id = kern_type_id; *vtype = kern_vtype; *vtype_id = kern_vtype_id; *data_member = kern_data_member; return 0; } static bool bpf_map__is_struct_ops(const struct bpf_map *map) { return map->def.type == BPF_MAP_TYPE_STRUCT_OPS; } /* Init the map's fields that depend on kern_btf */ static int bpf_map__init_kern_struct_ops(struct bpf_map *map, const struct btf *btf, const struct btf *kern_btf) { const struct btf_member *member, *kern_member, *kern_data_member; const struct btf_type *type, *kern_type, *kern_vtype; __u32 i, kern_type_id, kern_vtype_id, kern_data_off; struct bpf_struct_ops *st_ops; void *data, *kern_data; const char *tname; int err; st_ops = map->st_ops; type = st_ops->type; tname = st_ops->tname; err = find_struct_ops_kern_types(kern_btf, tname, &kern_type, &kern_type_id, &kern_vtype, &kern_vtype_id, &kern_data_member); if (err) return err; pr_debug("struct_ops init_kern %s: type_id:%u kern_type_id:%u kern_vtype_id:%u\n", map->name, st_ops->type_id, kern_type_id, kern_vtype_id); map->def.value_size = kern_vtype->size; map->btf_vmlinux_value_type_id = kern_vtype_id; st_ops->kern_vdata = calloc(1, kern_vtype->size); if (!st_ops->kern_vdata) return -ENOMEM; data = st_ops->data; kern_data_off = kern_data_member->offset / 8; kern_data = st_ops->kern_vdata + kern_data_off; member = btf_members(type); for (i = 0; i < btf_vlen(type); i++, member++) { const struct btf_type *mtype, *kern_mtype; __u32 mtype_id, kern_mtype_id; void *mdata, *kern_mdata; __s64 msize, kern_msize; __u32 moff, kern_moff; __u32 kern_member_idx; const char *mname; mname = btf__name_by_offset(btf, member->name_off); kern_member = find_member_by_name(kern_btf, kern_type, mname); if (!kern_member) { pr_warn("struct_ops init_kern %s: Cannot find member %s in kernel BTF\n", map->name, mname); return -ENOTSUP; } kern_member_idx = kern_member - btf_members(kern_type); if (btf_member_bitfield_size(type, i) || btf_member_bitfield_size(kern_type, kern_member_idx)) { pr_warn("struct_ops init_kern %s: bitfield %s is not supported\n", map->name, mname); return -ENOTSUP; } moff = member->offset / 8; kern_moff = kern_member->offset / 8; mdata = data + moff; kern_mdata = kern_data + kern_moff; mtype = skip_mods_and_typedefs(btf, member->type, &mtype_id); kern_mtype = skip_mods_and_typedefs(kern_btf, kern_member->type, &kern_mtype_id); if (BTF_INFO_KIND(mtype->info) != BTF_INFO_KIND(kern_mtype->info)) { pr_warn("struct_ops init_kern %s: Unmatched member type %s %u != %u(kernel)\n", map->name, mname, BTF_INFO_KIND(mtype->info), BTF_INFO_KIND(kern_mtype->info)); return -ENOTSUP; } if (btf_is_ptr(mtype)) { struct bpf_program *prog; prog = st_ops->progs[i]; if (!prog) continue; kern_mtype = skip_mods_and_typedefs(kern_btf, kern_mtype->type, &kern_mtype_id); /* mtype->type must be a func_proto which was * guaranteed in bpf_object__collect_st_ops_relos(), * so only check kern_mtype for func_proto here. */ if (!btf_is_func_proto(kern_mtype)) { pr_warn("struct_ops init_kern %s: kernel member %s is not a func ptr\n", map->name, mname); return -ENOTSUP; } prog->attach_btf_id = kern_type_id; prog->expected_attach_type = kern_member_idx; st_ops->kern_func_off[i] = kern_data_off + kern_moff; pr_debug("struct_ops init_kern %s: func ptr %s is set to prog %s from data(+%u) to kern_data(+%u)\n", map->name, mname, prog->name, moff, kern_moff); continue; } msize = btf__resolve_size(btf, mtype_id); kern_msize = btf__resolve_size(kern_btf, kern_mtype_id); if (msize < 0 || kern_msize < 0 || msize != kern_msize) { pr_warn("struct_ops init_kern %s: Error in size of member %s: %zd != %zd(kernel)\n", map->name, mname, (ssize_t)msize, (ssize_t)kern_msize); return -ENOTSUP; } pr_debug("struct_ops init_kern %s: copy %s %u bytes from data(+%u) to kern_data(+%u)\n", map->name, mname, (unsigned int)msize, moff, kern_moff); memcpy(kern_mdata, mdata, msize); } return 0; } static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj) { struct bpf_map *map; size_t i; int err; for (i = 0; i < obj->nr_maps; i++) { map = &obj->maps[i]; if (!bpf_map__is_struct_ops(map)) continue; err = bpf_map__init_kern_struct_ops(map, obj->btf, obj->btf_vmlinux); if (err) return err; } return 0; } static int bpf_object__init_struct_ops_maps(struct bpf_object *obj) { const struct btf_type *type, *datasec; const struct btf_var_secinfo *vsi; struct bpf_struct_ops *st_ops; const char *tname, *var_name; __s32 type_id, datasec_id; const struct btf *btf; struct bpf_map *map; __u32 i; if (obj->efile.st_ops_shndx == -1) return 0; btf = obj->btf; datasec_id = btf__find_by_name_kind(btf, STRUCT_OPS_SEC, BTF_KIND_DATASEC); if (datasec_id < 0) { pr_warn("struct_ops init: DATASEC %s not found\n", STRUCT_OPS_SEC); return -EINVAL; } datasec = btf__type_by_id(btf, datasec_id); vsi = btf_var_secinfos(datasec); for (i = 0; i < btf_vlen(datasec); i++, vsi++) { type = btf__type_by_id(obj->btf, vsi->type); var_name = btf__name_by_offset(obj->btf, type->name_off); type_id = btf__resolve_type(obj->btf, vsi->type); if (type_id < 0) { pr_warn("struct_ops init: Cannot resolve var type_id %u in DATASEC %s\n", vsi->type, STRUCT_OPS_SEC); return -EINVAL; } type = btf__type_by_id(obj->btf, type_id); tname = btf__name_by_offset(obj->btf, type->name_off); if (!tname[0]) { pr_warn("struct_ops init: anonymous type is not supported\n"); return -ENOTSUP; } if (!btf_is_struct(type)) { pr_warn("struct_ops init: %s is not a struct\n", tname); return -EINVAL; } map = bpf_object__add_map(obj); if (IS_ERR(map)) return PTR_ERR(map); map->sec_idx = obj->efile.st_ops_shndx; map->sec_offset = vsi->offset; map->name = strdup(var_name); if (!map->name) return -ENOMEM; map->def.type = BPF_MAP_TYPE_STRUCT_OPS; map->def.key_size = sizeof(int); map->def.value_size = type->size; map->def.max_entries = 1; map->st_ops = calloc(1, sizeof(*map->st_ops)); if (!map->st_ops) return -ENOMEM; st_ops = map->st_ops; st_ops->data = malloc(type->size); st_ops->progs = calloc(btf_vlen(type), sizeof(*st_ops->progs)); st_ops->kern_func_off = malloc(btf_vlen(type) * sizeof(*st_ops->kern_func_off)); if (!st_ops->data || !st_ops->progs || !st_ops->kern_func_off) return -ENOMEM; if (vsi->offset + type->size > obj->efile.st_ops_data->d_size) { pr_warn("struct_ops init: var %s is beyond the end of DATASEC %s\n", var_name, STRUCT_OPS_SEC); return -EINVAL; } memcpy(st_ops->data, obj->efile.st_ops_data->d_buf + vsi->offset, type->size); st_ops->tname = tname; st_ops->type = type; st_ops->type_id = type_id; pr_debug("struct_ops init: struct %s(type_id=%u) %s found at offset %u\n", tname, type_id, var_name, vsi->offset); } return 0; } static struct bpf_object *bpf_object__new(const char *path, const void *obj_buf, size_t obj_buf_sz, const char *obj_name) { struct bpf_object *obj; char *end; obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1); if (!obj) { pr_warn("alloc memory failed for %s\n", path); return ERR_PTR(-ENOMEM); } strcpy(obj->path, path); if (obj_name) { strncpy(obj->name, obj_name, sizeof(obj->name) - 1); obj->name[sizeof(obj->name) - 1] = 0; } else { /* Using basename() GNU version which doesn't modify arg. */ strncpy(obj->name, basename((void *)path), sizeof(obj->name) - 1); end = strchr(obj->name, '.'); if (end) *end = 0; } obj->efile.fd = -1; /* * Caller of this function should also call * bpf_object__elf_finish() after data collection to return * obj_buf to user. If not, we should duplicate the buffer to * avoid user freeing them before elf finish. */ obj->efile.obj_buf = obj_buf; obj->efile.obj_buf_sz = obj_buf_sz; obj->efile.maps_shndx = -1; obj->efile.btf_maps_shndx = -1; obj->efile.data_shndx = -1; obj->efile.rodata_shndx = -1; obj->efile.bss_shndx = -1; obj->efile.st_ops_shndx = -1; obj->kconfig_map_idx = -1; obj->rodata_map_idx = -1; obj->kern_version = get_kernel_version(); obj->loaded = false; INIT_LIST_HEAD(&obj->list); list_add(&obj->list, &bpf_objects_list); return obj; } static void bpf_object__elf_finish(struct bpf_object *obj) { if (!obj_elf_valid(obj)) return; if (obj->efile.elf) { elf_end(obj->efile.elf); obj->efile.elf = NULL; } obj->efile.symbols = NULL; obj->efile.data = NULL; obj->efile.rodata = NULL; obj->efile.bss = NULL; obj->efile.st_ops_data = NULL; zfree(&obj->efile.reloc_sects); obj->efile.nr_reloc_sects = 0; zclose(obj->efile.fd); obj->efile.obj_buf = NULL; obj->efile.obj_buf_sz = 0; } static int bpf_object__elf_init(struct bpf_object *obj) { int err = 0; GElf_Ehdr *ep; if (obj_elf_valid(obj)) { pr_warn("elf: init internal error\n"); return -LIBBPF_ERRNO__LIBELF; } if (obj->efile.obj_buf_sz > 0) { /* * obj_buf should have been validated by * bpf_object__open_buffer(). */ obj->efile.elf = elf_memory((char *)obj->efile.obj_buf, obj->efile.obj_buf_sz); } else { obj->efile.fd = open(obj->path, O_RDONLY); if (obj->efile.fd < 0) { char errmsg[STRERR_BUFSIZE], *cp; err = -errno; cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg)); pr_warn("elf: failed to open %s: %s\n", obj->path, cp); return err; } obj->efile.elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL); } if (!obj->efile.elf) { pr_warn("elf: failed to open %s as ELF file: %s\n", obj->path, elf_errmsg(-1)); err = -LIBBPF_ERRNO__LIBELF; goto errout; } if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) { pr_warn("elf: failed to get ELF header from %s: %s\n", obj->path, elf_errmsg(-1)); err = -LIBBPF_ERRNO__FORMAT; goto errout; } ep = &obj->efile.ehdr; if (elf_getshdrstrndx(obj->efile.elf, &obj->efile.shstrndx)) { pr_warn("elf: failed to get section names section index for %s: %s\n", obj->path, elf_errmsg(-1)); err = -LIBBPF_ERRNO__FORMAT; goto errout; } /* Elf is corrupted/truncated, avoid calling elf_strptr. */ if (!elf_rawdata(elf_getscn(obj->efile.elf, obj->efile.shstrndx), NULL)) { pr_warn("elf: failed to get section names strings from %s: %s\n", obj->path, elf_errmsg(-1)); err = -LIBBPF_ERRNO__FORMAT; goto errout; } /* Old LLVM set e_machine to EM_NONE */ if (ep->e_type != ET_REL || (ep->e_machine && ep->e_machine != EM_BPF)) { pr_warn("elf: %s is not a valid eBPF object file\n", obj->path); err = -LIBBPF_ERRNO__FORMAT; goto errout; } return 0; errout: bpf_object__elf_finish(obj); return err; } static int bpf_object__check_endianness(struct bpf_object *obj) { #if __BYTE_ORDER == __LITTLE_ENDIAN if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB) return 0; #elif __BYTE_ORDER == __BIG_ENDIAN if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB) return 0; #else # error "Unrecognized __BYTE_ORDER__" #endif pr_warn("elf: endianness mismatch in %s.\n", obj->path); return -LIBBPF_ERRNO__ENDIAN; } static int bpf_object__init_license(struct bpf_object *obj, void *data, size_t size) { memcpy(obj->license, data, min(size, sizeof(obj->license) - 1)); pr_debug("license of %s is %s\n", obj->path, obj->license); return 0; } static int bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size) { __u32 kver; if (size != sizeof(kver)) { pr_warn("invalid kver section in %s\n", obj->path); return -LIBBPF_ERRNO__FORMAT; } memcpy(&kver, data, sizeof(kver)); obj->kern_version = kver; pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version); return 0; } static bool bpf_map_type__is_map_in_map(enum bpf_map_type type) { if (type == BPF_MAP_TYPE_ARRAY_OF_MAPS || type == BPF_MAP_TYPE_HASH_OF_MAPS) return true; return false; } int bpf_object__section_size(const struct bpf_object *obj, const char *name, __u32 *size) { int ret = -ENOENT; *size = 0; if (!name) { return -EINVAL; } else if (!strcmp(name, DATA_SEC)) { if (obj->efile.data) *size = obj->efile.data->d_size; } else if (!strcmp(name, BSS_SEC)) { if (obj->efile.bss) *size = obj->efile.bss->d_size; } else if (!strcmp(name, RODATA_SEC)) { if (obj->efile.rodata) *size = obj->efile.rodata->d_size; } else if (!strcmp(name, STRUCT_OPS_SEC)) { if (obj->efile.st_ops_data) *size = obj->efile.st_ops_data->d_size; } else { Elf_Scn *scn = elf_sec_by_name(obj, name); Elf_Data *data = elf_sec_data(obj, scn); if (data) { ret = 0; /* found it */ *size = data->d_size; } } return *size ? 0 : ret; } int bpf_object__variable_offset(const struct bpf_object *obj, const char *name, __u32 *off) { Elf_Data *symbols = obj->efile.symbols; const char *sname; size_t si; if (!name || !off) return -EINVAL; for (si = 0; si < symbols->d_size / sizeof(GElf_Sym); si++) { GElf_Sym sym; if (!gelf_getsym(symbols, si, &sym)) continue; if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL || GELF_ST_TYPE(sym.st_info) != STT_OBJECT) continue; sname = elf_sym_str(obj, sym.st_name); if (!sname) { pr_warn("failed to get sym name string for var %s\n", name); return -EIO; } if (strcmp(name, sname) == 0) { *off = sym.st_value; return 0; } } return -ENOENT; } static struct bpf_map *bpf_object__add_map(struct bpf_object *obj) { struct bpf_map *new_maps; size_t new_cap; int i; if (obj->nr_maps < obj->maps_cap) return &obj->maps[obj->nr_maps++]; new_cap = max((size_t)4, obj->maps_cap * 3 / 2); new_maps = libbpf_reallocarray(obj->maps, new_cap, sizeof(*obj->maps)); if (!new_maps) { pr_warn("alloc maps for object failed\n"); return ERR_PTR(-ENOMEM); } obj->maps_cap = new_cap; obj->maps = new_maps; /* zero out new maps */ memset(obj->maps + obj->nr_maps, 0, (obj->maps_cap - obj->nr_maps) * sizeof(*obj->maps)); /* * fill all fd with -1 so won't close incorrect fd (fd=0 is stdin) * when failure (zclose won't close negative fd)). */ for (i = obj->nr_maps; i < obj->maps_cap; i++) { obj->maps[i].fd = -1; obj->maps[i].inner_map_fd = -1; } return &obj->maps[obj->nr_maps++]; } static size_t bpf_map_mmap_sz(const struct bpf_map *map) { long page_sz = sysconf(_SC_PAGE_SIZE); size_t map_sz; map_sz = (size_t)roundup(map->def.value_size, 8) * map->def.max_entries; map_sz = roundup(map_sz, page_sz); return map_sz; } static char *internal_map_name(struct bpf_object *obj, enum libbpf_map_type type) { char map_name[BPF_OBJ_NAME_LEN], *p; const char *sfx = libbpf_type_to_btf_name[type]; int sfx_len = max((size_t)7, strlen(sfx)); int pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1, strlen(obj->name)); snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name, sfx_len, libbpf_type_to_btf_name[type]); /* sanitise map name to characters allowed by kernel */ for (p = map_name; *p && p < map_name + sizeof(map_name); p++) if (!isalnum(*p) && *p != '_' && *p != '.') *p = '_'; return strdup(map_name); } static int bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type, int sec_idx, void *data, size_t data_sz) { struct bpf_map_def *def; struct bpf_map *map; int err; map = bpf_object__add_map(obj); if (IS_ERR(map)) return PTR_ERR(map); map->libbpf_type = type; map->sec_idx = sec_idx; map->sec_offset = 0; map->name = internal_map_name(obj, type); if (!map->name) { pr_warn("failed to alloc map name\n"); return -ENOMEM; } def = &map->def; def->type = BPF_MAP_TYPE_ARRAY; def->key_size = sizeof(int); def->value_size = data_sz; def->max_entries = 1; def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_KCONFIG ? BPF_F_RDONLY_PROG : 0; def->map_flags |= BPF_F_MMAPABLE; pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n", map->name, map->sec_idx, map->sec_offset, def->map_flags); map->mmaped = mmap(NULL, bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); if (map->mmaped == MAP_FAILED) { err = -errno; map->mmaped = NULL; pr_warn("failed to alloc map '%s' content buffer: %d\n", map->name, err); zfree(&map->name); return err; } if (data) memcpy(map->mmaped, data, data_sz); pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name); return 0; } static int bpf_object__init_global_data_maps(struct bpf_object *obj) { int err; /* * Populate obj->maps with libbpf internal maps. */ if (obj->efile.data_shndx >= 0) { err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA, obj->efile.data_shndx, obj->efile.data->d_buf, obj->efile.data->d_size); if (err) return err; } if (obj->efile.rodata_shndx >= 0) { err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA, obj->efile.rodata_shndx, obj->efile.rodata->d_buf, obj->efile.rodata->d_size); if (err) return err; obj->rodata_map_idx = obj->nr_maps - 1; } if (obj->efile.bss_shndx >= 0) { err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS, obj->efile.bss_shndx, NULL, obj->efile.bss->d_size); if (err) return err; } return 0; } static struct extern_desc *find_extern_by_name(const struct bpf_object *obj, const void *name) { int i; for (i = 0; i < obj->nr_extern; i++) { if (strcmp(obj->externs[i].name, name) == 0) return &obj->externs[i]; } return NULL; } static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val, char value) { switch (ext->kcfg.type) { case KCFG_BOOL: if (value == 'm') { pr_warn("extern (kcfg) %s=%c should be tristate or char\n", ext->name, value); return -EINVAL; } *(bool *)ext_val = value == 'y' ? true : false; break; case KCFG_TRISTATE: if (value == 'y') *(enum libbpf_tristate *)ext_val = TRI_YES; else if (value == 'm') *(enum libbpf_tristate *)ext_val = TRI_MODULE; else /* value == 'n' */ *(enum libbpf_tristate *)ext_val = TRI_NO; break; case KCFG_CHAR: *(char *)ext_val = value; break; case KCFG_UNKNOWN: case KCFG_INT: case KCFG_CHAR_ARR: default: pr_warn("extern (kcfg) %s=%c should be bool, tristate, or char\n", ext->name, value); return -EINVAL; } ext->is_set = true; return 0; } static int set_kcfg_value_str(struct extern_desc *ext, char *ext_val, const char *value) { size_t len; if (ext->kcfg.type != KCFG_CHAR_ARR) { pr_warn("extern (kcfg) %s=%s should be char array\n", ext->name, value); return -EINVAL; } len = strlen(value); if (value[len - 1] != '"') { pr_warn("extern (kcfg) '%s': invalid string config '%s'\n", ext->name, value); return -EINVAL; } /* strip quotes */ len -= 2; if (len >= ext->kcfg.sz) { pr_warn("extern (kcfg) '%s': long string config %s of (%zu bytes) truncated to %d bytes\n", ext->name, value, len, ext->kcfg.sz - 1); len = ext->kcfg.sz - 1; } memcpy(ext_val, value + 1, len); ext_val[len] = '\0'; ext->is_set = true; return 0; } static int parse_u64(const char *value, __u64 *res) { char *value_end; int err; errno = 0; *res = strtoull(value, &value_end, 0); if (errno) { err = -errno; pr_warn("failed to parse '%s' as integer: %d\n", value, err); return err; } if (*value_end) { pr_warn("failed to parse '%s' as integer completely\n", value); return -EINVAL; } return 0; } static bool is_kcfg_value_in_range(const struct extern_desc *ext, __u64 v) { int bit_sz = ext->kcfg.sz * 8; if (ext->kcfg.sz == 8) return true; /* Validate that value stored in u64 fits in integer of `ext->sz` * bytes size without any loss of information. If the target integer * is signed, we rely on the following limits of integer type of * Y bits and subsequent transformation: * * -2^(Y-1) <= X <= 2^(Y-1) - 1 * 0 <= X + 2^(Y-1) <= 2^Y - 1 * 0 <= X + 2^(Y-1) < 2^Y * * For unsigned target integer, check that all the (64 - Y) bits are * zero. */ if (ext->kcfg.is_signed) return v + (1ULL << (bit_sz - 1)) < (1ULL << bit_sz); else return (v >> bit_sz) == 0; } static int set_kcfg_value_num(struct extern_desc *ext, void *ext_val, __u64 value) { if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR) { pr_warn("extern (kcfg) %s=%llu should be integer\n", ext->name, (unsigned long long)value); return -EINVAL; } if (!is_kcfg_value_in_range(ext, value)) { pr_warn("extern (kcfg) %s=%llu value doesn't fit in %d bytes\n", ext->name, (unsigned long long)value, ext->kcfg.sz); return -ERANGE; } switch (ext->kcfg.sz) { case 1: *(__u8 *)ext_val = value; break; case 2: *(__u16 *)ext_val = value; break; case 4: *(__u32 *)ext_val = value; break; case 8: *(__u64 *)ext_val = value; break; default: return -EINVAL; } ext->is_set = true; return 0; } static int bpf_object__process_kconfig_line(struct bpf_object *obj, char *buf, void *data) { struct extern_desc *ext; char *sep, *value; int len, err = 0; void *ext_val; __u64 num; if (strncmp(buf, "CONFIG_", 7)) return 0; sep = strchr(buf, '='); if (!sep) { pr_warn("failed to parse '%s': no separator\n", buf); return -EINVAL; } /* Trim ending '\n' */ len = strlen(buf); if (buf[len - 1] == '\n') buf[len - 1] = '\0'; /* Split on '=' and ensure that a value is present. */ *sep = '\0'; if (!sep[1]) { *sep = '='; pr_warn("failed to parse '%s': no value\n", buf); return -EINVAL; } ext = find_extern_by_name(obj, buf); if (!ext || ext->is_set) return 0; ext_val = data + ext->kcfg.data_off; value = sep + 1; switch (*value) { case 'y': case 'n': case 'm': err = set_kcfg_value_tri(ext, ext_val, *value); break; case '"': err = set_kcfg_value_str(ext, ext_val, value); break; default: /* assume integer */ err = parse_u64(value, &num); if (err) { pr_warn("extern (kcfg) %s=%s should be integer\n", ext->name, value); return err; } err = set_kcfg_value_num(ext, ext_val, num); break; } if (err) return err; pr_debug("extern (kcfg) %s=%s\n", ext->name, value); return 0; } static int bpf_object__read_kconfig_file(struct bpf_object *obj, void *data) { char buf[PATH_MAX]; struct utsname uts; int len, err = 0; gzFile file; uname(&uts); len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release); if (len < 0) return -EINVAL; else if (len >= PATH_MAX) return -ENAMETOOLONG; /* gzopen also accepts uncompressed files. */ file = gzopen(buf, "r"); if (!file) file = gzopen("/proc/config.gz", "r"); if (!file) { pr_warn("failed to open system Kconfig\n"); return -ENOENT; } while (gzgets(file, buf, sizeof(buf))) { err = bpf_object__process_kconfig_line(obj, buf, data); if (err) { pr_warn("error parsing system Kconfig line '%s': %d\n", buf, err); goto out; } } out: gzclose(file); return err; } static int bpf_object__read_kconfig_mem(struct bpf_object *obj, const char *config, void *data) { char buf[PATH_MAX]; int err = 0; FILE *file; file = fmemopen((void *)config, strlen(config), "r"); if (!file) { err = -errno; pr_warn("failed to open in-memory Kconfig: %d\n", err); return err; } while (fgets(buf, sizeof(buf), file)) { err = bpf_object__process_kconfig_line(obj, buf, data); if (err) { pr_warn("error parsing in-memory Kconfig line '%s': %d\n", buf, err); break; } } fclose(file); return err; } static int bpf_object__init_kconfig_map(struct bpf_object *obj) { struct extern_desc *last_ext = NULL, *ext; size_t map_sz; int i, err; for (i = 0; i < obj->nr_extern; i++) { ext = &obj->externs[i]; if (ext->type == EXT_KCFG) last_ext = ext; } if (!last_ext) return 0; map_sz = last_ext->kcfg.data_off + last_ext->kcfg.sz; err = bpf_object__init_internal_map(obj, LIBBPF_MAP_KCONFIG, obj->efile.symbols_shndx, NULL, map_sz); if (err) return err; obj->kconfig_map_idx = obj->nr_maps - 1; return 0; } static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict) { Elf_Data *symbols = obj->efile.symbols; int i, map_def_sz = 0, nr_maps = 0, nr_syms; Elf_Data *data = NULL; Elf_Scn *scn; if (obj->efile.maps_shndx < 0) return 0; if (!symbols) return -EINVAL; scn = elf_sec_by_idx(obj, obj->efile.maps_shndx); data = elf_sec_data(obj, scn); if (!scn || !data) { pr_warn("elf: failed to get legacy map definitions for %s\n", obj->path); return -EINVAL; } /* * Count number of maps. Each map has a name. * Array of maps is not supported: only the first element is * considered. * * TODO: Detect array of map and report error. */ nr_syms = symbols->d_size / sizeof(GElf_Sym); for (i = 0; i < nr_syms; i++) { GElf_Sym sym; if (!gelf_getsym(symbols, i, &sym)) continue; if (sym.st_shndx != obj->efile.maps_shndx) continue; nr_maps++; } /* Assume equally sized map definitions */ pr_debug("elf: found %d legacy map definitions (%zd bytes) in %s\n", nr_maps, data->d_size, obj->path); if (!data->d_size || nr_maps == 0 || (data->d_size % nr_maps) != 0) { pr_warn("elf: unable to determine legacy map definition size in %s\n", obj->path); return -EINVAL; } map_def_sz = data->d_size / nr_maps; /* Fill obj->maps using data in "maps" section. */ for (i = 0; i < nr_syms; i++) { GElf_Sym sym; const char *map_name; struct bpf_map_def *def; struct bpf_map *map; if (!gelf_getsym(symbols, i, &sym)) continue; if (sym.st_shndx != obj->efile.maps_shndx) continue; map = bpf_object__add_map(obj); if (IS_ERR(map)) return PTR_ERR(map); map_name = elf_sym_str(obj, sym.st_name); if (!map_name) { pr_warn("failed to get map #%d name sym string for obj %s\n", i, obj->path); return -LIBBPF_ERRNO__FORMAT; } map->libbpf_type = LIBBPF_MAP_UNSPEC; map->sec_idx = sym.st_shndx; map->sec_offset = sym.st_value; pr_debug("map '%s' (legacy): at sec_idx %d, offset %zu.\n", map_name, map->sec_idx, map->sec_offset); if (sym.st_value + map_def_sz > data->d_size) { pr_warn("corrupted maps section in %s: last map \"%s\" too small\n", obj->path, map_name); return -EINVAL; } map->name = strdup(map_name); if (!map->name) { pr_warn("failed to alloc map name\n"); return -ENOMEM; } pr_debug("map %d is \"%s\"\n", i, map->name); def = (struct bpf_map_def *)(data->d_buf + sym.st_value); /* * If the definition of the map in the object file fits in * bpf_map_def, copy it. Any extra fields in our version * of bpf_map_def will default to zero as a result of the * calloc above. */ if (map_def_sz <= sizeof(struct bpf_map_def)) { memcpy(&map->def, def, map_def_sz); } else { /* * Here the map structure being read is bigger than what * we expect, truncate if the excess bits are all zero. * If they are not zero, reject this map as * incompatible. */ char *b; for (b = ((char *)def) + sizeof(struct bpf_map_def); b < ((char *)def) + map_def_sz; b++) { if (*b != 0) { pr_warn("maps section in %s: \"%s\" has unrecognized, non-zero options\n", obj->path, map_name); if (strict) return -EINVAL; } } memcpy(&map->def, def, sizeof(struct bpf_map_def)); } } return 0; } const struct btf_type * skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id) { const struct btf_type *t = btf__type_by_id(btf, id); if (res_id) *res_id = id; while (btf_is_mod(t) || btf_is_typedef(t)) { if (res_id) *res_id = t->type; t = btf__type_by_id(btf, t->type); } return t; } static const struct btf_type * resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id) { const struct btf_type *t; t = skip_mods_and_typedefs(btf, id, NULL); if (!btf_is_ptr(t)) return NULL; t = skip_mods_and_typedefs(btf, t->type, res_id); return btf_is_func_proto(t) ? t : NULL; } static const char *__btf_kind_str(__u16 kind) { switch (kind) { case BTF_KIND_UNKN: return "void"; case BTF_KIND_INT: return "int"; case BTF_KIND_PTR: return "ptr"; case BTF_KIND_ARRAY: return "array"; case BTF_KIND_STRUCT: return "struct"; case BTF_KIND_UNION: return "union"; case BTF_KIND_ENUM: return "enum"; case BTF_KIND_FWD: return "fwd"; case BTF_KIND_TYPEDEF: return "typedef"; case BTF_KIND_VOLATILE: return "volatile"; case BTF_KIND_CONST: return "const"; case BTF_KIND_RESTRICT: return "restrict"; case BTF_KIND_FUNC: return "func"; case BTF_KIND_FUNC_PROTO: return "func_proto"; case BTF_KIND_VAR: return "var"; case BTF_KIND_DATASEC: return "datasec"; case BTF_KIND_FLOAT: return "float"; default: return "unknown"; } } const char *btf_kind_str(const struct btf_type *t) { return __btf_kind_str(btf_kind(t)); } /* * Fetch integer attribute of BTF map definition. Such attributes are * represented using a pointer to an array, in which dimensionality of array * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY]; * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF * type definition, while using only sizeof(void *) space in ELF data section. */ static bool get_map_field_int(const char *map_name, const struct btf *btf, const struct btf_member *m, __u32 *res) { const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL); const char *name = btf__name_by_offset(btf, m->name_off); const struct btf_array *arr_info; const struct btf_type *arr_t; if (!btf_is_ptr(t)) { pr_warn("map '%s': attr '%s': expected PTR, got %s.\n", map_name, name, btf_kind_str(t)); return false; } arr_t = btf__type_by_id(btf, t->type); if (!arr_t) { pr_warn("map '%s': attr '%s': type [%u] not found.\n", map_name, name, t->type); return false; } if (!btf_is_array(arr_t)) { pr_warn("map '%s': attr '%s': expected ARRAY, got %s.\n", map_name, name, btf_kind_str(arr_t)); return false; } arr_info = btf_array(arr_t); *res = arr_info->nelems; return true; } static int build_map_pin_path(struct bpf_map *map, const char *path) { char buf[PATH_MAX]; int len; if (!path) path = "/sys/fs/bpf"; len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map)); if (len < 0) return -EINVAL; else if (len >= PATH_MAX) return -ENAMETOOLONG; return bpf_map__set_pin_path(map, buf); } int parse_btf_map_def(const char *map_name, struct btf *btf, const struct btf_type *def_t, bool strict, struct btf_map_def *map_def, struct btf_map_def *inner_def) { const struct btf_type *t; const struct btf_member *m; bool is_inner = inner_def == NULL; int vlen, i; vlen = btf_vlen(def_t); m = btf_members(def_t); for (i = 0; i < vlen; i++, m++) { const char *name = btf__name_by_offset(btf, m->name_off); if (!name) { pr_warn("map '%s': invalid field #%d.\n", map_name, i); return -EINVAL; } if (strcmp(name, "type") == 0) { if (!get_map_field_int(map_name, btf, m, &map_def->map_type)) return -EINVAL; map_def->parts |= MAP_DEF_MAP_TYPE; } else if (strcmp(name, "max_entries") == 0) { if (!get_map_field_int(map_name, btf, m, &map_def->max_entries)) return -EINVAL; map_def->parts |= MAP_DEF_MAX_ENTRIES; } else if (strcmp(name, "map_flags") == 0) { if (!get_map_field_int(map_name, btf, m, &map_def->map_flags)) return -EINVAL; map_def->parts |= MAP_DEF_MAP_FLAGS; } else if (strcmp(name, "numa_node") == 0) { if (!get_map_field_int(map_name, btf, m, &map_def->numa_node)) return -EINVAL; map_def->parts |= MAP_DEF_NUMA_NODE; } else if (strcmp(name, "key_size") == 0) { __u32 sz; if (!get_map_field_int(map_name, btf, m, &sz)) return -EINVAL; if (map_def->key_size && map_def->key_size != sz) { pr_warn("map '%s': conflicting key size %u != %u.\n", map_name, map_def->key_size, sz); return -EINVAL; } map_def->key_size = sz; map_def->parts |= MAP_DEF_KEY_SIZE; } else if (strcmp(name, "key") == 0) { __s64 sz; t = btf__type_by_id(btf, m->type); if (!t) { pr_warn("map '%s': key type [%d] not found.\n", map_name, m->type); return -EINVAL; } if (!btf_is_ptr(t)) { pr_warn("map '%s': key spec is not PTR: %s.\n", map_name, btf_kind_str(t)); return -EINVAL; } sz = btf__resolve_size(btf, t->type); if (sz < 0) { pr_warn("map '%s': can't determine key size for type [%u]: %zd.\n", map_name, t->type, (ssize_t)sz); return sz; } if (map_def->key_size && map_def->key_size != sz) { pr_warn("map '%s': conflicting key size %u != %zd.\n", map_name, map_def->key_size, (ssize_t)sz); return -EINVAL; } map_def->key_size = sz; map_def->key_type_id = t->type; map_def->parts |= MAP_DEF_KEY_SIZE | MAP_DEF_KEY_TYPE; } else if (strcmp(name, "value_size") == 0) { __u32 sz; if (!get_map_field_int(map_name, btf, m, &sz)) return -EINVAL; if (map_def->value_size && map_def->value_size != sz) { pr_warn("map '%s': conflicting value size %u != %u.\n", map_name, map_def->value_size, sz); return -EINVAL; } map_def->value_size = sz; map_def->parts |= MAP_DEF_VALUE_SIZE; } else if (strcmp(name, "value") == 0) { __s64 sz; t = btf__type_by_id(btf, m->type); if (!t) { pr_warn("map '%s': value type [%d] not found.\n", map_name, m->type); return -EINVAL; } if (!btf_is_ptr(t)) { pr_warn("map '%s': value spec is not PTR: %s.\n", map_name, btf_kind_str(t)); return -EINVAL; } sz = btf__resolve_size(btf, t->type); if (sz < 0) { pr_warn("map '%s': can't determine value size for type [%u]: %zd.\n", map_name, t->type, (ssize_t)sz); return sz; } if (map_def->value_size && map_def->value_size != sz) { pr_warn("map '%s': conflicting value size %u != %zd.\n", map_name, map_def->value_size, (ssize_t)sz); return -EINVAL; } map_def->value_size = sz; map_def->value_type_id = t->type; map_def->parts |= MAP_DEF_VALUE_SIZE | MAP_DEF_VALUE_TYPE; } else if (strcmp(name, "values") == 0) { char inner_map_name[128]; int err; if (is_inner) { pr_warn("map '%s': multi-level inner maps not supported.\n", map_name); return -ENOTSUP; } if (i != vlen - 1) { pr_warn("map '%s': '%s' member should be last.\n", map_name, name); return -EINVAL; } if (!bpf_map_type__is_map_in_map(map_def->map_type)) { pr_warn("map '%s': should be map-in-map.\n", map_name); return -ENOTSUP; } if (map_def->value_size && map_def->value_size != 4) { pr_warn("map '%s': conflicting value size %u != 4.\n", map_name, map_def->value_size); return -EINVAL; } map_def->value_size = 4; t = btf__type_by_id(btf, m->type); if (!t) { pr_warn("map '%s': map-in-map inner type [%d] not found.\n", map_name, m->type); return -EINVAL; } if (!btf_is_array(t) || btf_array(t)->nelems) { pr_warn("map '%s': map-in-map inner spec is not a zero-sized array.\n", map_name); return -EINVAL; } t = skip_mods_and_typedefs(btf, btf_array(t)->type, NULL); if (!btf_is_ptr(t)) { pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n", map_name, btf_kind_str(t)); return -EINVAL; } t = skip_mods_and_typedefs(btf, t->type, NULL); if (!btf_is_struct(t)) { pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n", map_name, btf_kind_str(t)); return -EINVAL; } snprintf(inner_map_name, sizeof(inner_map_name), "%s.inner", map_name); err = parse_btf_map_def(inner_map_name, btf, t, strict, inner_def, NULL); if (err) return err; map_def->parts |= MAP_DEF_INNER_MAP; } else if (strcmp(name, "pinning") == 0) { __u32 val; if (is_inner) { pr_warn("map '%s': inner def can't be pinned.\n", map_name); return -EINVAL; } if (!get_map_field_int(map_name, btf, m, &val)) return -EINVAL; if (val != LIBBPF_PIN_NONE && val != LIBBPF_PIN_BY_NAME) { pr_warn("map '%s': invalid pinning value %u.\n", map_name, val); return -EINVAL; } map_def->pinning = val; map_def->parts |= MAP_DEF_PINNING; } else { if (strict) { pr_warn("map '%s': unknown field '%s'.\n", map_name, name); return -ENOTSUP; } pr_debug("map '%s': ignoring unknown field '%s'.\n", map_name, name); } } if (map_def->map_type == BPF_MAP_TYPE_UNSPEC) { pr_warn("map '%s': map type isn't specified.\n", map_name); return -EINVAL; } return 0; } static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def) { map->def.type = def->map_type; map->def.key_size = def->key_size; map->def.value_size = def->value_size; map->def.max_entries = def->max_entries; map->def.map_flags = def->map_flags; map->numa_node = def->numa_node; map->btf_key_type_id = def->key_type_id; map->btf_value_type_id = def->value_type_id; if (def->parts & MAP_DEF_MAP_TYPE) pr_debug("map '%s': found type = %u.\n", map->name, def->map_type); if (def->parts & MAP_DEF_KEY_TYPE) pr_debug("map '%s': found key [%u], sz = %u.\n", map->name, def->key_type_id, def->key_size); else if (def->parts & MAP_DEF_KEY_SIZE) pr_debug("map '%s': found key_size = %u.\n", map->name, def->key_size); if (def->parts & MAP_DEF_VALUE_TYPE) pr_debug("map '%s': found value [%u], sz = %u.\n", map->name, def->value_type_id, def->value_size); else if (def->parts & MAP_DEF_VALUE_SIZE) pr_debug("map '%s': found value_size = %u.\n", map->name, def->value_size); if (def->parts & MAP_DEF_MAX_ENTRIES) pr_debug("map '%s': found max_entries = %u.\n", map->name, def->max_entries); if (def->parts & MAP_DEF_MAP_FLAGS) pr_debug("map '%s': found map_flags = %u.\n", map->name, def->map_flags); if (def->parts & MAP_DEF_PINNING) pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning); if (def->parts & MAP_DEF_NUMA_NODE) pr_debug("map '%s': found numa_node = %u.\n", map->name, def->numa_node); if (def->parts & MAP_DEF_INNER_MAP) pr_debug("map '%s': found inner map definition.\n", map->name); } static int bpf_object__init_user_btf_map(struct bpf_object *obj, const struct btf_type *sec, int var_idx, int sec_idx, const Elf_Data *data, bool strict, const char *pin_root_path) { struct btf_map_def map_def = {}, inner_def = {}; const struct btf_type *var, *def; const struct btf_var_secinfo *vi; const struct btf_var *var_extra; const char *map_name; struct bpf_map *map; int err; vi = btf_var_secinfos(sec) + var_idx; var = btf__type_by_id(obj->btf, vi->type); var_extra = btf_var(var); map_name = btf__name_by_offset(obj->btf, var->name_off); if (map_name == NULL || map_name[0] == '\0') { pr_warn("map #%d: empty name.\n", var_idx); return -EINVAL; } if ((__u64)vi->offset + vi->size > data->d_size) { pr_warn("map '%s' BTF data is corrupted.\n", map_name); return -EINVAL; } if (!btf_is_var(var)) { pr_warn("map '%s': unexpected var kind %s.\n", map_name, btf_kind_str(var)); return -EINVAL; } if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED && var_extra->linkage != BTF_VAR_STATIC) { pr_warn("map '%s': unsupported var linkage %u.\n", map_name, var_extra->linkage); return -EOPNOTSUPP; } def = skip_mods_and_typedefs(obj->btf, var->type, NULL); if (!btf_is_struct(def)) { pr_warn("map '%s': unexpected def kind %s.\n", map_name, btf_kind_str(var)); return -EINVAL; } if (def->size > vi->size) { pr_warn("map '%s': invalid def size.\n", map_name); return -EINVAL; } map = bpf_object__add_map(obj); if (IS_ERR(map)) return PTR_ERR(map); map->name = strdup(map_name); if (!map->name) { pr_warn("map '%s': failed to alloc map name.\n", map_name); return -ENOMEM; } map->libbpf_type = LIBBPF_MAP_UNSPEC; map->def.type = BPF_MAP_TYPE_UNSPEC; map->sec_idx = sec_idx; map->sec_offset = vi->offset; map->btf_var_idx = var_idx; pr_debug("map '%s': at sec_idx %d, offset %zu.\n", map_name, map->sec_idx, map->sec_offset); err = parse_btf_map_def(map->name, obj->btf, def, strict, &map_def, &inner_def); if (err) return err; fill_map_from_def(map, &map_def); if (map_def.pinning == LIBBPF_PIN_BY_NAME) { err = build_map_pin_path(map, pin_root_path); if (err) { pr_warn("map '%s': couldn't build pin path.\n", map->name); return err; } } if (map_def.parts & MAP_DEF_INNER_MAP) { map->inner_map = calloc(1, sizeof(*map->inner_map)); if (!map->inner_map) return -ENOMEM; map->inner_map->fd = -1; map->inner_map->sec_idx = sec_idx; map->inner_map->name = malloc(strlen(map_name) + sizeof(".inner") + 1); if (!map->inner_map->name) return -ENOMEM; sprintf(map->inner_map->name, "%s.inner", map_name); fill_map_from_def(map->inner_map, &inner_def); } return 0; } static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict, const char *pin_root_path) { const struct btf_type *sec = NULL; int nr_types, i, vlen, err; const struct btf_type *t; const char *name; Elf_Data *data; Elf_Scn *scn; if (obj->efile.btf_maps_shndx < 0) return 0; scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx); data = elf_sec_data(obj, scn); if (!scn || !data) { pr_warn("elf: failed to get %s map definitions for %s\n", MAPS_ELF_SEC, obj->path); return -EINVAL; } nr_types = btf__get_nr_types(obj->btf); for (i = 1; i <= nr_types; i++) { t = btf__type_by_id(obj->btf, i); if (!btf_is_datasec(t)) continue; name = btf__name_by_offset(obj->btf, t->name_off); if (strcmp(name, MAPS_ELF_SEC) == 0) { sec = t; obj->efile.btf_maps_sec_btf_id = i; break; } } if (!sec) { pr_warn("DATASEC '%s' not found.\n", MAPS_ELF_SEC); return -ENOENT; } vlen = btf_vlen(sec); for (i = 0; i < vlen; i++) { err = bpf_object__init_user_btf_map(obj, sec, i, obj->efile.btf_maps_shndx, data, strict, pin_root_path); if (err) return err; } return 0; } static int bpf_object__init_maps(struct bpf_object *obj, const struct bpf_object_open_opts *opts) { const char *pin_root_path; bool strict; int err; strict = !OPTS_GET(opts, relaxed_maps, false); pin_root_path = OPTS_GET(opts, pin_root_path, NULL); err = bpf_object__init_user_maps(obj, strict); err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path); err = err ?: bpf_object__init_global_data_maps(obj); err = err ?: bpf_object__init_kconfig_map(obj); err = err ?: bpf_object__init_struct_ops_maps(obj); if (err) return err; return 0; } static bool section_have_execinstr(struct bpf_object *obj, int idx) { GElf_Shdr sh; if (elf_sec_hdr(obj, elf_sec_by_idx(obj, idx), &sh)) return false; return sh.sh_flags & SHF_EXECINSTR; } static bool btf_needs_sanitization(struct bpf_object *obj) { bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC); bool has_datasec = kernel_supports(FEAT_BTF_DATASEC); bool has_float = kernel_supports(FEAT_BTF_FLOAT); bool has_func = kernel_supports(FEAT_BTF_FUNC); return !has_func || !has_datasec || !has_func_global || !has_float; } static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf) { bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC); bool has_datasec = kernel_supports(FEAT_BTF_DATASEC); bool has_float = kernel_supports(FEAT_BTF_FLOAT); bool has_func = kernel_supports(FEAT_BTF_FUNC); struct btf_type *t; int i, j, vlen; for (i = 1; i <= btf__get_nr_types(btf); i++) { t = (struct btf_type *)btf__type_by_id(btf, i); if (!has_datasec && btf_is_var(t)) { /* replace VAR with INT */ t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0); /* * using size = 1 is the safest choice, 4 will be too * big and cause kernel BTF validation failure if * original variable took less than 4 bytes */ t->size = 1; *(int *)(t + 1) = BTF_INT_ENC(0, 0, 8); } else if (!has_datasec && btf_is_datasec(t)) { /* replace DATASEC with STRUCT */ const struct btf_var_secinfo *v = btf_var_secinfos(t); struct btf_member *m = btf_members(t); struct btf_type *vt; char *name; name = (char *)btf__name_by_offset(btf, t->name_off); while (*name) { if (*name == '.') *name = '_'; name++; } vlen = btf_vlen(t); t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen); for (j = 0; j < vlen; j++, v++, m++) { /* order of field assignments is important */ m->offset = v->offset * 8; m->type = v->type; /* preserve variable name as member name */ vt = (void *)btf__type_by_id(btf, v->type); m->name_off = vt->name_off; } } else if (!has_func && btf_is_func_proto(t)) { /* replace FUNC_PROTO with ENUM */ vlen = btf_vlen(t); t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen); t->size = sizeof(__u32); /* kernel enforced */ } else if (!has_func && btf_is_func(t)) { /* replace FUNC with TYPEDEF */ t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0); } else if (!has_func_global && btf_is_func(t)) { /* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */ t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0); } else if (!has_float && btf_is_float(t)) { /* replace FLOAT with an equally-sized empty STRUCT; * since C compilers do not accept e.g. "float" as a * valid struct name, make it anonymous */ t->name_off = 0; t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0); } } } static bool libbpf_needs_btf(const struct bpf_object *obj) { return obj->efile.btf_maps_shndx >= 0 || obj->efile.st_ops_shndx >= 0 || obj->nr_extern > 0; } static bool kernel_needs_btf(const struct bpf_object *obj) { return obj->efile.st_ops_shndx >= 0; } static int bpf_object__init_btf(struct bpf_object *obj, Elf_Data *btf_data, Elf_Data *btf_ext_data) { int err = -ENOENT; if (btf_data) { obj->btf = btf__new(btf_data->d_buf, btf_data->d_size); if (IS_ERR(obj->btf)) { err = PTR_ERR(obj->btf); obj->btf = NULL; pr_warn("Error loading ELF section %s: %d.\n", BTF_ELF_SEC, err); goto out; } /* enforce 8-byte pointers for BPF-targeted BTFs */ btf__set_pointer_size(obj->btf, 8); err = 0; } if (btf_ext_data) { if (!obj->btf) { pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n", BTF_EXT_ELF_SEC, BTF_ELF_SEC); goto out; } obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size); if (IS_ERR(obj->btf_ext)) { pr_warn("Error loading ELF section %s: %ld. Ignored and continue.\n", BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext)); obj->btf_ext = NULL; goto out; } } out: if (err && libbpf_needs_btf(obj)) { pr_warn("BTF is required, but is missing or corrupted.\n"); return err; } return 0; } static int bpf_object__finalize_btf(struct bpf_object *obj) { int err; if (!obj->btf) return 0; err = btf__finalize_data(obj, obj->btf); if (err) { pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err); return err; } return 0; } static bool prog_needs_vmlinux_btf(struct bpf_program *prog) { if (prog->type == BPF_PROG_TYPE_STRUCT_OPS || prog->type == BPF_PROG_TYPE_LSM) return true; /* BPF_PROG_TYPE_TRACING programs which do not attach to other programs * also need vmlinux BTF */ if (prog->type == BPF_PROG_TYPE_TRACING && !prog->attach_prog_fd) return true; return false; } static bool obj_needs_vmlinux_btf(const struct bpf_object *obj) { struct bpf_program *prog; int i; /* CO-RE relocations need kernel BTF */ if (obj->btf_ext && obj->btf_ext->core_relo_info.len) return true; /* Support for typed ksyms needs kernel BTF */ for (i = 0; i < obj->nr_extern; i++) { const struct extern_desc *ext; ext = &obj->externs[i]; if (ext->type == EXT_KSYM && ext->ksym.type_id) return true; } bpf_object__for_each_program(prog, obj) { if (!prog->load) continue; if (prog_needs_vmlinux_btf(prog)) return true; } return false; } static int bpf_object__load_vmlinux_btf(struct bpf_object *obj, bool force) { int err; /* btf_vmlinux could be loaded earlier */ if (obj->btf_vmlinux) return 0; if (!force && !obj_needs_vmlinux_btf(obj)) return 0; obj->btf_vmlinux = libbpf_find_kernel_btf(); if (IS_ERR(obj->btf_vmlinux)) { err = PTR_ERR(obj->btf_vmlinux); pr_warn("Error loading vmlinux BTF: %d\n", err); obj->btf_vmlinux = NULL; return err; } return 0; } static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj) { struct btf *kern_btf = obj->btf; bool btf_mandatory, sanitize; int i, err = 0; if (!obj->btf) return 0; if (!kernel_supports(FEAT_BTF)) { if (kernel_needs_btf(obj)) { err = -EOPNOTSUPP; goto report; } pr_debug("Kernel doesn't support BTF, skipping uploading it.\n"); return 0; } /* Even though some subprogs are global/weak, user might prefer more * permissive BPF verification process that BPF verifier performs for * static functions, taking into account more context from the caller * functions. In such case, they need to mark such subprogs with * __attribute__((visibility("hidden"))) and libbpf will adjust * corresponding FUNC BTF type to be marked as static and trigger more * involved BPF verification process. */ for (i = 0; i < obj->nr_programs; i++) { struct bpf_program *prog = &obj->programs[i]; struct btf_type *t; const char *name; int j, n; if (!prog->mark_btf_static || !prog_is_subprog(obj, prog)) continue; n = btf__get_nr_types(obj->btf); for (j = 1; j <= n; j++) { t = btf_type_by_id(obj->btf, j); if (!btf_is_func(t) || btf_func_linkage(t) != BTF_FUNC_GLOBAL) continue; name = btf__str_by_offset(obj->btf, t->name_off); if (strcmp(name, prog->name) != 0) continue; t->info = btf_type_info(BTF_KIND_FUNC, BTF_FUNC_STATIC, 0); break; } } sanitize = btf_needs_sanitization(obj); if (sanitize) { const void *raw_data; __u32 sz; /* clone BTF to sanitize a copy and leave the original intact */ raw_data = btf__get_raw_data(obj->btf, &sz); kern_btf = btf__new(raw_data, sz); if (IS_ERR(kern_btf)) return PTR_ERR(kern_btf); /* enforce 8-byte pointers for BPF-targeted BTFs */ btf__set_pointer_size(obj->btf, 8); bpf_object__sanitize_btf(obj, kern_btf); } err = btf__load(kern_btf); if (sanitize) { if (!err) { /* move fd to libbpf's BTF */ btf__set_fd(obj->btf, btf__fd(kern_btf)); btf__set_fd(kern_btf, -1); } btf__free(kern_btf); } report: if (err) { btf_mandatory = kernel_needs_btf(obj); pr_warn("Error loading .BTF into kernel: %d. %s\n", err, btf_mandatory ? "BTF is mandatory, can't proceed." : "BTF is optional, ignoring."); if (!btf_mandatory) err = 0; } return err; } static const char *elf_sym_str(const struct bpf_object *obj, size_t off) { const char *name; name = elf_strptr(obj->efile.elf, obj->efile.strtabidx, off); if (!name) { pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n", off, obj->path, elf_errmsg(-1)); return NULL; } return name; } static const char *elf_sec_str(const struct bpf_object *obj, size_t off) { const char *name; name = elf_strptr(obj->efile.elf, obj->efile.shstrndx, off); if (!name) { pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n", off, obj->path, elf_errmsg(-1)); return NULL; } return name; } static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx) { Elf_Scn *scn; scn = elf_getscn(obj->efile.elf, idx); if (!scn) { pr_warn("elf: failed to get section(%zu) from %s: %s\n", idx, obj->path, elf_errmsg(-1)); return NULL; } return scn; } static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name) { Elf_Scn *scn = NULL; Elf *elf = obj->efile.elf; const char *sec_name; while ((scn = elf_nextscn(elf, scn)) != NULL) { sec_name = elf_sec_name(obj, scn); if (!sec_name) return NULL; if (strcmp(sec_name, name) != 0) continue; return scn; } return NULL; } static int elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn, GElf_Shdr *hdr) { if (!scn) return -EINVAL; if (gelf_getshdr(scn, hdr) != hdr) { pr_warn("elf: failed to get section(%zu) header from %s: %s\n", elf_ndxscn(scn), obj->path, elf_errmsg(-1)); return -EINVAL; } return 0; } static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn) { const char *name; GElf_Shdr sh; if (!scn) return NULL; if (elf_sec_hdr(obj, scn, &sh)) return NULL; name = elf_sec_str(obj, sh.sh_name); if (!name) { pr_warn("elf: failed to get section(%zu) name from %s: %s\n", elf_ndxscn(scn), obj->path, elf_errmsg(-1)); return NULL; } return name; } static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn) { Elf_Data *data; if (!scn) return NULL; data = elf_getdata(scn, 0); if (!data) { pr_warn("elf: failed to get section(%zu) %s data from %s: %s\n", elf_ndxscn(scn), elf_sec_name(obj, scn) ?: "", obj->path, elf_errmsg(-1)); return NULL; } return data; } static bool is_sec_name_dwarf(const char *name) { /* approximation, but the actual list is too long */ return strncmp(name, ".debug_", sizeof(".debug_") - 1) == 0; } static bool ignore_elf_section(GElf_Shdr *hdr, const char *name) { /* no special handling of .strtab */ if (hdr->sh_type == SHT_STRTAB) return true; /* ignore .llvm_addrsig section as well */ if (hdr->sh_type == SHT_LLVM_ADDRSIG) return true; /* no subprograms will lead to an empty .text section, ignore it */ if (hdr->sh_type == SHT_PROGBITS && hdr->sh_size == 0 && strcmp(name, ".text") == 0) return true; /* DWARF sections */ if (is_sec_name_dwarf(name)) return true; if (strncmp(name, ".rel", sizeof(".rel") - 1) == 0) { name += sizeof(".rel") - 1; /* DWARF section relocations */ if (is_sec_name_dwarf(name)) return true; /* .BTF and .BTF.ext don't need relocations */ if (strcmp(name, BTF_ELF_SEC) == 0 || strcmp(name, BTF_EXT_ELF_SEC) == 0) return true; } return false; } static int cmp_progs(const void *_a, const void *_b) { const struct bpf_program *a = _a; const struct bpf_program *b = _b; if (a->sec_idx != b->sec_idx) return a->sec_idx < b->sec_idx ? -1 : 1; /* sec_insn_off can't be the same within the section */ return a->sec_insn_off < b->sec_insn_off ? -1 : 1; } static int bpf_object__elf_collect(struct bpf_object *obj) { Elf *elf = obj->efile.elf; Elf_Data *btf_ext_data = NULL; Elf_Data *btf_data = NULL; int idx = 0, err = 0; const char *name; Elf_Data *data; Elf_Scn *scn; GElf_Shdr sh; /* a bunch of ELF parsing functionality depends on processing symbols, * so do the first pass and find the symbol table */ scn = NULL; while ((scn = elf_nextscn(elf, scn)) != NULL) { if (elf_sec_hdr(obj, scn, &sh)) return -LIBBPF_ERRNO__FORMAT; if (sh.sh_type == SHT_SYMTAB) { if (obj->efile.symbols) { pr_warn("elf: multiple symbol tables in %s\n", obj->path); return -LIBBPF_ERRNO__FORMAT; } data = elf_sec_data(obj, scn); if (!data) return -LIBBPF_ERRNO__FORMAT; obj->efile.symbols = data; obj->efile.symbols_shndx = elf_ndxscn(scn); obj->efile.strtabidx = sh.sh_link; } } scn = NULL; while ((scn = elf_nextscn(elf, scn)) != NULL) { idx++; if (elf_sec_hdr(obj, scn, &sh)) return -LIBBPF_ERRNO__FORMAT; name = elf_sec_str(obj, sh.sh_name); if (!name) return -LIBBPF_ERRNO__FORMAT; if (ignore_elf_section(&sh, name)) continue; data = elf_sec_data(obj, scn); if (!data) return -LIBBPF_ERRNO__FORMAT; pr_debug("elf: section(%d) %s, size %ld, link %d, flags %lx, type=%d\n", idx, name, (unsigned long)data->d_size, (int)sh.sh_link, (unsigned long)sh.sh_flags, (int)sh.sh_type); if (strcmp(name, "license") == 0) { err = bpf_object__init_license(obj, data->d_buf, data->d_size); if (err) return err; } else if (strcmp(name, "version") == 0) { err = bpf_object__init_kversion(obj, data->d_buf, data->d_size); if (err) return err; } else if (strcmp(name, "maps") == 0) { obj->efile.maps_shndx = idx; } else if (strcmp(name, MAPS_ELF_SEC) == 0) { obj->efile.btf_maps_shndx = idx; } else if (strcmp(name, BTF_ELF_SEC) == 0) { btf_data = data; } else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) { btf_ext_data = data; } else if (sh.sh_type == SHT_SYMTAB) { /* already processed during the first pass above */ } else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) { if (sh.sh_flags & SHF_EXECINSTR) { if (strcmp(name, ".text") == 0) obj->efile.text_shndx = idx; err = bpf_object__add_programs(obj, data, name, idx); if (err) return err; } else if (strcmp(name, DATA_SEC) == 0) { obj->efile.data = data; obj->efile.data_shndx = idx; } else if (strcmp(name, RODATA_SEC) == 0) { obj->efile.rodata = data; obj->efile.rodata_shndx = idx; } else if (strcmp(name, STRUCT_OPS_SEC) == 0) { obj->efile.st_ops_data = data; obj->efile.st_ops_shndx = idx; } else { pr_info("elf: skipping unrecognized data section(%d) %s\n", idx, name); } } else if (sh.sh_type == SHT_REL) { int nr_sects = obj->efile.nr_reloc_sects; void *sects = obj->efile.reloc_sects; int sec = sh.sh_info; /* points to other section */ /* Only do relo for section with exec instructions */ if (!section_have_execinstr(obj, sec) && strcmp(name, ".rel" STRUCT_OPS_SEC) && strcmp(name, ".rel" MAPS_ELF_SEC)) { pr_info("elf: skipping relo section(%d) %s for section(%d) %s\n", idx, name, sec, elf_sec_name(obj, elf_sec_by_idx(obj, sec)) ?: ""); continue; } sects = libbpf_reallocarray(sects, nr_sects + 1, sizeof(*obj->efile.reloc_sects)); if (!sects) return -ENOMEM; obj->efile.reloc_sects = sects; obj->efile.nr_reloc_sects++; obj->efile.reloc_sects[nr_sects].shdr = sh; obj->efile.reloc_sects[nr_sects].data = data; } else if (sh.sh_type == SHT_NOBITS && strcmp(name, BSS_SEC) == 0) { obj->efile.bss = data; obj->efile.bss_shndx = idx; } else { pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name, (size_t)sh.sh_size); } } if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) { pr_warn("elf: symbol strings section missing or invalid in %s\n", obj->path); return -LIBBPF_ERRNO__FORMAT; } /* sort BPF programs by section name and in-section instruction offset * for faster search */ qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs); return bpf_object__init_btf(obj, btf_data, btf_ext_data); } static bool sym_is_extern(const GElf_Sym *sym) { int bind = GELF_ST_BIND(sym->st_info); /* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */ return sym->st_shndx == SHN_UNDEF && (bind == STB_GLOBAL || bind == STB_WEAK) && GELF_ST_TYPE(sym->st_info) == STT_NOTYPE; } static bool sym_is_subprog(const GElf_Sym *sym, int text_shndx) { int bind = GELF_ST_BIND(sym->st_info); int type = GELF_ST_TYPE(sym->st_info); /* in .text section */ if (sym->st_shndx != text_shndx) return false; /* local function */ if (bind == STB_LOCAL && type == STT_SECTION) return true; /* global function */ return bind == STB_GLOBAL && type == STT_FUNC; } static int find_extern_btf_id(const struct btf *btf, const char *ext_name) { const struct btf_type *t; const char *tname; int i, n; if (!btf) return -ESRCH; n = btf__get_nr_types(btf); for (i = 1; i <= n; i++) { t = btf__type_by_id(btf, i); if (!btf_is_var(t) && !btf_is_func(t)) continue; tname = btf__name_by_offset(btf, t->name_off); if (strcmp(tname, ext_name)) continue; if (btf_is_var(t) && btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN) return -EINVAL; if (btf_is_func(t) && btf_func_linkage(t) != BTF_FUNC_EXTERN) return -EINVAL; return i; } return -ENOENT; } static int find_extern_sec_btf_id(struct btf *btf, int ext_btf_id) { const struct btf_var_secinfo *vs; const struct btf_type *t; int i, j, n; if (!btf) return -ESRCH; n = btf__get_nr_types(btf); for (i = 1; i <= n; i++) { t = btf__type_by_id(btf, i); if (!btf_is_datasec(t)) continue; vs = btf_var_secinfos(t); for (j = 0; j < btf_vlen(t); j++, vs++) { if (vs->type == ext_btf_id) return i; } } return -ENOENT; } static enum kcfg_type find_kcfg_type(const struct btf *btf, int id, bool *is_signed) { const struct btf_type *t; const char *name; t = skip_mods_and_typedefs(btf, id, NULL); name = btf__name_by_offset(btf, t->name_off); if (is_signed) *is_signed = false; switch (btf_kind(t)) { case BTF_KIND_INT: { int enc = btf_int_encoding(t); if (enc & BTF_INT_BOOL) return t->size == 1 ? KCFG_BOOL : KCFG_UNKNOWN; if (is_signed) *is_signed = enc & BTF_INT_SIGNED; if (t->size == 1) return KCFG_CHAR; if (t->size < 1 || t->size > 8 || (t->size & (t->size - 1))) return KCFG_UNKNOWN; return KCFG_INT; } case BTF_KIND_ENUM: if (t->size != 4) return KCFG_UNKNOWN; if (strcmp(name, "libbpf_tristate")) return KCFG_UNKNOWN; return KCFG_TRISTATE; case BTF_KIND_ARRAY: if (btf_array(t)->nelems == 0) return KCFG_UNKNOWN; if (find_kcfg_type(btf, btf_array(t)->type, NULL) != KCFG_CHAR) return KCFG_UNKNOWN; return KCFG_CHAR_ARR; default: return KCFG_UNKNOWN; } } static int cmp_externs(const void *_a, const void *_b) { const struct extern_desc *a = _a; const struct extern_desc *b = _b; if (a->type != b->type) return a->type < b->type ? -1 : 1; if (a->type == EXT_KCFG) { /* descending order by alignment requirements */ if (a->kcfg.align != b->kcfg.align) return a->kcfg.align > b->kcfg.align ? -1 : 1; /* ascending order by size, within same alignment class */ if (a->kcfg.sz != b->kcfg.sz) return a->kcfg.sz < b->kcfg.sz ? -1 : 1; } /* resolve ties by name */ return strcmp(a->name, b->name); } static int find_int_btf_id(const struct btf *btf) { const struct btf_type *t; int i, n; n = btf__get_nr_types(btf); for (i = 1; i <= n; i++) { t = btf__type_by_id(btf, i); if (btf_is_int(t) && btf_int_bits(t) == 32) return i; } return 0; } static int add_dummy_ksym_var(struct btf *btf) { int i, int_btf_id, sec_btf_id, dummy_var_btf_id; const struct btf_var_secinfo *vs; const struct btf_type *sec; if (!btf) return 0; sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC, BTF_KIND_DATASEC); if (sec_btf_id < 0) return 0; sec = btf__type_by_id(btf, sec_btf_id); vs = btf_var_secinfos(sec); for (i = 0; i < btf_vlen(sec); i++, vs++) { const struct btf_type *vt; vt = btf__type_by_id(btf, vs->type); if (btf_is_func(vt)) break; } /* No func in ksyms sec. No need to add dummy var. */ if (i == btf_vlen(sec)) return 0; int_btf_id = find_int_btf_id(btf); dummy_var_btf_id = btf__add_var(btf, "dummy_ksym", BTF_VAR_GLOBAL_ALLOCATED, int_btf_id); if (dummy_var_btf_id < 0) pr_warn("cannot create a dummy_ksym var\n"); return dummy_var_btf_id; } static int bpf_object__collect_externs(struct bpf_object *obj) { struct btf_type *sec, *kcfg_sec = NULL, *ksym_sec = NULL; const struct btf_type *t; struct extern_desc *ext; int i, n, off, dummy_var_btf_id; const char *ext_name, *sec_name; Elf_Scn *scn; GElf_Shdr sh; if (!obj->efile.symbols) return 0; scn = elf_sec_by_idx(obj, obj->efile.symbols_shndx); if (elf_sec_hdr(obj, scn, &sh)) return -LIBBPF_ERRNO__FORMAT; dummy_var_btf_id = add_dummy_ksym_var(obj->btf); if (dummy_var_btf_id < 0) return dummy_var_btf_id; n = sh.sh_size / sh.sh_entsize; pr_debug("looking for externs among %d symbols...\n", n); for (i = 0; i < n; i++) { GElf_Sym sym; if (!gelf_getsym(obj->efile.symbols, i, &sym)) return -LIBBPF_ERRNO__FORMAT; if (!sym_is_extern(&sym)) continue; ext_name = elf_sym_str(obj, sym.st_name); if (!ext_name || !ext_name[0]) continue; ext = obj->externs; ext = libbpf_reallocarray(ext, obj->nr_extern + 1, sizeof(*ext)); if (!ext) return -ENOMEM; obj->externs = ext; ext = &ext[obj->nr_extern]; memset(ext, 0, sizeof(*ext)); obj->nr_extern++; ext->btf_id = find_extern_btf_id(obj->btf, ext_name); if (ext->btf_id <= 0) { pr_warn("failed to find BTF for extern '%s': %d\n", ext_name, ext->btf_id); return ext->btf_id; } t = btf__type_by_id(obj->btf, ext->btf_id); ext->name = btf__name_by_offset(obj->btf, t->name_off); ext->sym_idx = i; ext->is_weak = GELF_ST_BIND(sym.st_info) == STB_WEAK; ext->sec_btf_id = find_extern_sec_btf_id(obj->btf, ext->btf_id); if (ext->sec_btf_id <= 0) { pr_warn("failed to find BTF for extern '%s' [%d] section: %d\n", ext_name, ext->btf_id, ext->sec_btf_id); return ext->sec_btf_id; } sec = (void *)btf__type_by_id(obj->btf, ext->sec_btf_id); sec_name = btf__name_by_offset(obj->btf, sec->name_off); if (strcmp(sec_name, KCONFIG_SEC) == 0) { if (btf_is_func(t)) { pr_warn("extern function %s is unsupported under %s section\n", ext->name, KCONFIG_SEC); return -ENOTSUP; } kcfg_sec = sec; ext->type = EXT_KCFG; ext->kcfg.sz = btf__resolve_size(obj->btf, t->type); if (ext->kcfg.sz <= 0) { pr_warn("failed to resolve size of extern (kcfg) '%s': %d\n", ext_name, ext->kcfg.sz); return ext->kcfg.sz; } ext->kcfg.align = btf__align_of(obj->btf, t->type); if (ext->kcfg.align <= 0) { pr_warn("failed to determine alignment of extern (kcfg) '%s': %d\n", ext_name, ext->kcfg.align); return -EINVAL; } ext->kcfg.type = find_kcfg_type(obj->btf, t->type, &ext->kcfg.is_signed); if (ext->kcfg.type == KCFG_UNKNOWN) { pr_warn("extern (kcfg) '%s' type is unsupported\n", ext_name); return -ENOTSUP; } } else if (strcmp(sec_name, KSYMS_SEC) == 0) { if (btf_is_func(t) && ext->is_weak) { pr_warn("extern weak function %s is unsupported\n", ext->name); return -ENOTSUP; } ksym_sec = sec; ext->type = EXT_KSYM; skip_mods_and_typedefs(obj->btf, t->type, &ext->ksym.type_id); } else { pr_warn("unrecognized extern section '%s'\n", sec_name); return -ENOTSUP; } } pr_debug("collected %d externs total\n", obj->nr_extern); if (!obj->nr_extern) return 0; /* sort externs by type, for kcfg ones also by (align, size, name) */ qsort(obj->externs, obj->nr_extern, sizeof(*ext), cmp_externs); /* for .ksyms section, we need to turn all externs into allocated * variables in BTF to pass kernel verification; we do this by * pretending that each extern is a 8-byte variable */ if (ksym_sec) { /* find existing 4-byte integer type in BTF to use for fake * extern variables in DATASEC */ int int_btf_id = find_int_btf_id(obj->btf); /* For extern function, a dummy_var added earlier * will be used to replace the vs->type and * its name string will be used to refill * the missing param's name. */ const struct btf_type *dummy_var; dummy_var = btf__type_by_id(obj->btf, dummy_var_btf_id); for (i = 0; i < obj->nr_extern; i++) { ext = &obj->externs[i]; if (ext->type != EXT_KSYM) continue; pr_debug("extern (ksym) #%d: symbol %d, name %s\n", i, ext->sym_idx, ext->name); } sec = ksym_sec; n = btf_vlen(sec); for (i = 0, off = 0; i < n; i++, off += sizeof(int)) { struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i; struct btf_type *vt; vt = (void *)btf__type_by_id(obj->btf, vs->type); ext_name = btf__name_by_offset(obj->btf, vt->name_off); ext = find_extern_by_name(obj, ext_name); if (!ext) { pr_warn("failed to find extern definition for BTF %s '%s'\n", btf_kind_str(vt), ext_name); return -ESRCH; } if (btf_is_func(vt)) { const struct btf_type *func_proto; struct btf_param *param; int j; func_proto = btf__type_by_id(obj->btf, vt->type); param = btf_params(func_proto); /* Reuse the dummy_var string if the * func proto does not have param name. */ for (j = 0; j < btf_vlen(func_proto); j++) if (param[j].type && !param[j].name_off) param[j].name_off = dummy_var->name_off; vs->type = dummy_var_btf_id; vt->info &= ~0xffff; vt->info |= BTF_FUNC_GLOBAL; } else { btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED; vt->type = int_btf_id; } vs->offset = off; vs->size = sizeof(int); } sec->size = off; } if (kcfg_sec) { sec = kcfg_sec; /* for kcfg externs calculate their offsets within a .kconfig map */ off = 0; for (i = 0; i < obj->nr_extern; i++) { ext = &obj->externs[i]; if (ext->type != EXT_KCFG) continue; ext->kcfg.data_off = roundup(off, ext->kcfg.align); off = ext->kcfg.data_off + ext->kcfg.sz; pr_debug("extern (kcfg) #%d: symbol %d, off %u, name %s\n", i, ext->sym_idx, ext->kcfg.data_off, ext->name); } sec->size = off; n = btf_vlen(sec); for (i = 0; i < n; i++) { struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i; t = btf__type_by_id(obj->btf, vs->type); ext_name = btf__name_by_offset(obj->btf, t->name_off); ext = find_extern_by_name(obj, ext_name); if (!ext) { pr_warn("failed to find extern definition for BTF var '%s'\n", ext_name); return -ESRCH; } btf_var(t)->linkage = BTF_VAR_GLOBAL_ALLOCATED; vs->offset = ext->kcfg.data_off; } } return 0; } struct bpf_program * bpf_object__find_program_by_title(const struct bpf_object *obj, const char *title) { struct bpf_program *pos; bpf_object__for_each_program(pos, obj) { if (pos->sec_name && !strcmp(pos->sec_name, title)) return pos; } return NULL; } static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog) { /* For legacy reasons, libbpf supports an entry-point BPF programs * without SEC() attribute, i.e., those in the .text section. But if * there are 2 or more such programs in the .text section, they all * must be subprograms called from entry-point BPF programs in * designated SEC()'tions, otherwise there is no way to distinguish * which of those programs should be loaded vs which are a subprogram. * Similarly, if there is a function/program in .text and at least one * other BPF program with custom SEC() attribute, then we just assume * .text programs are subprograms (even if they are not called from * other programs), because libbpf never explicitly supported mixing * SEC()-designated BPF programs and .text entry-point BPF programs. */ return prog->sec_idx == obj->efile.text_shndx && obj->nr_programs > 1; } struct bpf_program * bpf_object__find_program_by_name(const struct bpf_object *obj, const char *name) { struct bpf_program *prog; bpf_object__for_each_program(prog, obj) { if (prog_is_subprog(obj, prog)) continue; if (!strcmp(prog->name, name)) return prog; } return NULL; } static bool bpf_object__shndx_is_data(const struct bpf_object *obj, int shndx) { return shndx == obj->efile.data_shndx || shndx == obj->efile.bss_shndx || shndx == obj->efile.rodata_shndx; } static bool bpf_object__shndx_is_maps(const struct bpf_object *obj, int shndx) { return shndx == obj->efile.maps_shndx || shndx == obj->efile.btf_maps_shndx; } static enum libbpf_map_type bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx) { if (shndx == obj->efile.data_shndx) return LIBBPF_MAP_DATA; else if (shndx == obj->efile.bss_shndx) return LIBBPF_MAP_BSS; else if (shndx == obj->efile.rodata_shndx) return LIBBPF_MAP_RODATA; else if (shndx == obj->efile.symbols_shndx) return LIBBPF_MAP_KCONFIG; else return LIBBPF_MAP_UNSPEC; } static int bpf_program__record_reloc(struct bpf_program *prog, struct reloc_desc *reloc_desc, __u32 insn_idx, const char *sym_name, const GElf_Sym *sym, const GElf_Rel *rel) { struct bpf_insn *insn = &prog->insns[insn_idx]; size_t map_idx, nr_maps = prog->obj->nr_maps; struct bpf_object *obj = prog->obj; __u32 shdr_idx = sym->st_shndx; enum libbpf_map_type type; const char *sym_sec_name; struct bpf_map *map; if (!is_call_insn(insn) && !is_ldimm64_insn(insn)) { pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n", prog->name, sym_name, insn_idx, insn->code); return -LIBBPF_ERRNO__RELOC; } if (sym_is_extern(sym)) { int sym_idx = GELF_R_SYM(rel->r_info); int i, n = obj->nr_extern; struct extern_desc *ext; for (i = 0; i < n; i++) { ext = &obj->externs[i]; if (ext->sym_idx == sym_idx) break; } if (i >= n) { pr_warn("prog '%s': extern relo failed to find extern for '%s' (%d)\n", prog->name, sym_name, sym_idx); return -LIBBPF_ERRNO__RELOC; } pr_debug("prog '%s': found extern #%d '%s' (sym %d) for insn #%u\n", prog->name, i, ext->name, ext->sym_idx, insn_idx); if (insn->code == (BPF_JMP | BPF_CALL)) reloc_desc->type = RELO_EXTERN_FUNC; else reloc_desc->type = RELO_EXTERN_VAR; reloc_desc->insn_idx = insn_idx; reloc_desc->sym_off = i; /* sym_off stores extern index */ return 0; } /* sub-program call relocation */ if (is_call_insn(insn)) { if (insn->src_reg != BPF_PSEUDO_CALL) { pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name); return -LIBBPF_ERRNO__RELOC; } /* text_shndx can be 0, if no default "main" program exists */ if (!shdr_idx || shdr_idx != obj->efile.text_shndx) { sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx)); pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n", prog->name, sym_name, sym_sec_name); return -LIBBPF_ERRNO__RELOC; } if (sym->st_value % BPF_INSN_SZ) { pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n", prog->name, sym_name, (size_t)sym->st_value); return -LIBBPF_ERRNO__RELOC; } reloc_desc->type = RELO_CALL; reloc_desc->insn_idx = insn_idx; reloc_desc->sym_off = sym->st_value; return 0; } if (!shdr_idx || shdr_idx >= SHN_LORESERVE) { pr_warn("prog '%s': invalid relo against '%s' in special section 0x%x; forgot to initialize global var?..\n", prog->name, sym_name, shdr_idx); return -LIBBPF_ERRNO__RELOC; } /* loading subprog addresses */ if (sym_is_subprog(sym, obj->efile.text_shndx)) { /* global_func: sym->st_value = offset in the section, insn->imm = 0. * local_func: sym->st_value = 0, insn->imm = offset in the section. */ if ((sym->st_value % BPF_INSN_SZ) || (insn->imm % BPF_INSN_SZ)) { pr_warn("prog '%s': bad subprog addr relo against '%s' at offset %zu+%d\n", prog->name, sym_name, (size_t)sym->st_value, insn->imm); return -LIBBPF_ERRNO__RELOC; } reloc_desc->type = RELO_SUBPROG_ADDR; reloc_desc->insn_idx = insn_idx; reloc_desc->sym_off = sym->st_value; return 0; } type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx); sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx)); /* generic map reference relocation */ if (type == LIBBPF_MAP_UNSPEC) { if (!bpf_object__shndx_is_maps(obj, shdr_idx)) { pr_warn("prog '%s': bad map relo against '%s' in section '%s'\n", prog->name, sym_name, sym_sec_name); return -LIBBPF_ERRNO__RELOC; } for (map_idx = 0; map_idx < nr_maps; map_idx++) { map = &obj->maps[map_idx]; if (map->libbpf_type != type || map->sec_idx != sym->st_shndx || map->sec_offset != sym->st_value) continue; pr_debug("prog '%s': found map %zd (%s, sec %d, off %zu) for insn #%u\n", prog->name, map_idx, map->name, map->sec_idx, map->sec_offset, insn_idx); break; } if (map_idx >= nr_maps) { pr_warn("prog '%s': map relo failed to find map for section '%s', off %zu\n", prog->name, sym_sec_name, (size_t)sym->st_value); return -LIBBPF_ERRNO__RELOC; } reloc_desc->type = RELO_LD64; reloc_desc->insn_idx = insn_idx; reloc_desc->map_idx = map_idx; reloc_desc->sym_off = 0; /* sym->st_value determines map_idx */ return 0; } /* global data map relocation */ if (!bpf_object__shndx_is_data(obj, shdr_idx)) { pr_warn("prog '%s': bad data relo against section '%s'\n", prog->name, sym_sec_name); return -LIBBPF_ERRNO__RELOC; } for (map_idx = 0; map_idx < nr_maps; map_idx++) { map = &obj->maps[map_idx]; if (map->libbpf_type != type) continue; pr_debug("prog '%s': found data map %zd (%s, sec %d, off %zu) for insn %u\n", prog->name, map_idx, map->name, map->sec_idx, map->sec_offset, insn_idx); break; } if (map_idx >= nr_maps) { pr_warn("prog '%s': data relo failed to find map for section '%s'\n", prog->name, sym_sec_name); return -LIBBPF_ERRNO__RELOC; } reloc_desc->type = RELO_DATA; reloc_desc->insn_idx = insn_idx; reloc_desc->map_idx = map_idx; reloc_desc->sym_off = sym->st_value; return 0; } static bool prog_contains_insn(const struct bpf_program *prog, size_t insn_idx) { return insn_idx >= prog->sec_insn_off && insn_idx < prog->sec_insn_off + prog->sec_insn_cnt; } static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj, size_t sec_idx, size_t insn_idx) { int l = 0, r = obj->nr_programs - 1, m; struct bpf_program *prog; while (l < r) { m = l + (r - l + 1) / 2; prog = &obj->programs[m]; if (prog->sec_idx < sec_idx || (prog->sec_idx == sec_idx && prog->sec_insn_off <= insn_idx)) l = m; else r = m - 1; } /* matching program could be at index l, but it still might be the * wrong one, so we need to double check conditions for the last time */ prog = &obj->programs[l]; if (prog->sec_idx == sec_idx && prog_contains_insn(prog, insn_idx)) return prog; return NULL; } static int bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data) { Elf_Data *symbols = obj->efile.symbols; const char *relo_sec_name, *sec_name; size_t sec_idx = shdr->sh_info; struct bpf_program *prog; struct reloc_desc *relos; int err, i, nrels; const char *sym_name; __u32 insn_idx; Elf_Scn *scn; Elf_Data *scn_data; GElf_Sym sym; GElf_Rel rel; scn = elf_sec_by_idx(obj, sec_idx); scn_data = elf_sec_data(obj, scn); relo_sec_name = elf_sec_str(obj, shdr->sh_name); sec_name = elf_sec_name(obj, scn); if (!relo_sec_name || !sec_name) return -EINVAL; pr_debug("sec '%s': collecting relocation for section(%zu) '%s'\n", relo_sec_name, sec_idx, sec_name); nrels = shdr->sh_size / shdr->sh_entsize; for (i = 0; i < nrels; i++) { if (!gelf_getrel(data, i, &rel)) { pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i); return -LIBBPF_ERRNO__FORMAT; } if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) { pr_warn("sec '%s': symbol 0x%zx not found for relo #%d\n", relo_sec_name, (size_t)GELF_R_SYM(rel.r_info), i); return -LIBBPF_ERRNO__FORMAT; } if (rel.r_offset % BPF_INSN_SZ || rel.r_offset >= scn_data->d_size) { pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n", relo_sec_name, (size_t)GELF_R_SYM(rel.r_info), i); return -LIBBPF_ERRNO__FORMAT; } insn_idx = rel.r_offset / BPF_INSN_SZ; /* relocations against static functions are recorded as * relocations against the section that contains a function; * in such case, symbol will be STT_SECTION and sym.st_name * will point to empty string (0), so fetch section name * instead */ if (GELF_ST_TYPE(sym.st_info) == STT_SECTION && sym.st_name == 0) sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym.st_shndx)); else sym_name = elf_sym_str(obj, sym.st_name); sym_name = sym_name ?: "reloc_desc, prog->nr_reloc + 1, sizeof(*relos)); if (!relos) return -ENOMEM; prog->reloc_desc = relos; /* adjust insn_idx to local BPF program frame of reference */ insn_idx -= prog->sec_insn_off; err = bpf_program__record_reloc(prog, &relos[prog->nr_reloc], insn_idx, sym_name, &sym, &rel); if (err) return err; prog->nr_reloc++; } return 0; } static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map) { struct bpf_map_def *def = &map->def; __u32 key_type_id = 0, value_type_id = 0; int ret; /* if it's BTF-defined map, we don't need to search for type IDs. * For struct_ops map, it does not need btf_key_type_id and * btf_value_type_id. */ if (map->sec_idx == obj->efile.btf_maps_shndx || bpf_map__is_struct_ops(map)) return 0; if (!bpf_map__is_internal(map)) { ret = btf__get_map_kv_tids(obj->btf, map->name, def->key_size, def->value_size, &key_type_id, &value_type_id); } else { /* * LLVM annotates global data differently in BTF, that is, * only as '.data', '.bss' or '.rodata'. */ ret = btf__find_by_name(obj->btf, libbpf_type_to_btf_name[map->libbpf_type]); } if (ret < 0) return ret; map->btf_key_type_id = key_type_id; map->btf_value_type_id = bpf_map__is_internal(map) ? ret : value_type_id; return 0; } int bpf_map__reuse_fd(struct bpf_map *map, int fd) { struct bpf_map_info info = {}; __u32 len = sizeof(info); int new_fd, err; char *new_name; err = bpf_obj_get_info_by_fd(fd, &info, &len); if (err) return err; new_name = strdup(info.name); if (!new_name) return -errno; new_fd = open("/", O_RDONLY | O_CLOEXEC); if (new_fd < 0) { err = -errno; goto err_free_new_name; } new_fd = dup3(fd, new_fd, O_CLOEXEC); if (new_fd < 0) { err = -errno; goto err_close_new_fd; } err = zclose(map->fd); if (err) { err = -errno; goto err_close_new_fd; } free(map->name); map->fd = new_fd; map->name = new_name; map->def.type = info.type; map->def.key_size = info.key_size; map->def.value_size = info.value_size; map->def.max_entries = info.max_entries; map->def.map_flags = info.map_flags; map->btf_key_type_id = info.btf_key_type_id; map->btf_value_type_id = info.btf_value_type_id; map->reused = true; return 0; err_close_new_fd: close(new_fd); err_free_new_name: free(new_name); return err; } __u32 bpf_map__max_entries(const struct bpf_map *map) { return map->def.max_entries; } struct bpf_map *bpf_map__inner_map(struct bpf_map *map) { if (!bpf_map_type__is_map_in_map(map->def.type)) return NULL; return map->inner_map; } int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries) { if (map->fd >= 0) return -EBUSY; map->def.max_entries = max_entries; return 0; } int bpf_map__resize(struct bpf_map *map, __u32 max_entries) { if (!map || !max_entries) return -EINVAL; return bpf_map__set_max_entries(map, max_entries); } static int bpf_object__probe_loading(struct bpf_object *obj) { struct bpf_load_program_attr attr; char *cp, errmsg[STRERR_BUFSIZE]; struct bpf_insn insns[] = { BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }; int ret; /* make sure basic loading works */ memset(&attr, 0, sizeof(attr)); attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER; attr.insns = insns; attr.insns_cnt = ARRAY_SIZE(insns); attr.license = "GPL"; ret = bpf_load_program_xattr(&attr, NULL, 0); if (ret < 0) { ret = errno; cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); pr_warn("Error in %s():%s(%d). Couldn't load trivial BPF " "program. Make sure your kernel supports BPF " "(CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is " "set to big enough value.\n", __func__, cp, ret); return -ret; } close(ret); return 0; } static int probe_fd(int fd) { if (fd >= 0) close(fd); return fd >= 0; } static int probe_kern_prog_name(void) { struct bpf_load_program_attr attr; struct bpf_insn insns[] = { BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }; int ret; /* make sure loading with name works */ memset(&attr, 0, sizeof(attr)); attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER; attr.insns = insns; attr.insns_cnt = ARRAY_SIZE(insns); attr.license = "GPL"; attr.name = "test"; ret = bpf_load_program_xattr(&attr, NULL, 0); return probe_fd(ret); } static int probe_kern_global_data(void) { struct bpf_load_program_attr prg_attr; struct bpf_create_map_attr map_attr; char *cp, errmsg[STRERR_BUFSIZE]; struct bpf_insn insns[] = { BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16), BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }; int ret, map; memset(&map_attr, 0, sizeof(map_attr)); map_attr.map_type = BPF_MAP_TYPE_ARRAY; map_attr.key_size = sizeof(int); map_attr.value_size = 32; map_attr.max_entries = 1; map = bpf_create_map_xattr(&map_attr); if (map < 0) { ret = -errno; cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", __func__, cp, -ret); return ret; } insns[0].imm = map; memset(&prg_attr, 0, sizeof(prg_attr)); prg_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER; prg_attr.insns = insns; prg_attr.insns_cnt = ARRAY_SIZE(insns); prg_attr.license = "GPL"; ret = bpf_load_program_xattr(&prg_attr, NULL, 0); close(map); return probe_fd(ret); } static int probe_kern_btf(void) { static const char strs[] = "\0int"; __u32 types[] = { /* int */ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), }; return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs))); } static int probe_kern_btf_func(void) { static const char strs[] = "\0int\0x\0a"; /* void x(int a) {} */ __u32 types[] = { /* int */ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ /* FUNC_PROTO */ /* [2] */ BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0), BTF_PARAM_ENC(7, 1), /* FUNC x */ /* [3] */ BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2), }; return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs))); } static int probe_kern_btf_func_global(void) { static const char strs[] = "\0int\0x\0a"; /* static void x(int a) {} */ __u32 types[] = { /* int */ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ /* FUNC_PROTO */ /* [2] */ BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0), BTF_PARAM_ENC(7, 1), /* FUNC x BTF_FUNC_GLOBAL */ /* [3] */ BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2), }; return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs))); } static int probe_kern_btf_datasec(void) { static const char strs[] = "\0x\0.data"; /* static int a; */ __u32 types[] = { /* int */ BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ /* VAR x */ /* [2] */ BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1), BTF_VAR_STATIC, /* DATASEC val */ /* [3] */ BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4), BTF_VAR_SECINFO_ENC(2, 0, 4), }; return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs))); } static int probe_kern_btf_float(void) { static const char strs[] = "\0float"; __u32 types[] = { /* float */ BTF_TYPE_FLOAT_ENC(1, 4), }; return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs))); } static int probe_kern_array_mmap(void) { struct bpf_create_map_attr attr = { .map_type = BPF_MAP_TYPE_ARRAY, .map_flags = BPF_F_MMAPABLE, .key_size = sizeof(int), .value_size = sizeof(int), .max_entries = 1, }; return probe_fd(bpf_create_map_xattr(&attr)); } static int probe_kern_exp_attach_type(void) { struct bpf_load_program_attr attr; struct bpf_insn insns[] = { BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }; memset(&attr, 0, sizeof(attr)); /* use any valid combination of program type and (optional) * non-zero expected attach type (i.e., not a BPF_CGROUP_INET_INGRESS) * to see if kernel supports expected_attach_type field for * BPF_PROG_LOAD command */ attr.prog_type = BPF_PROG_TYPE_CGROUP_SOCK; attr.expected_attach_type = BPF_CGROUP_INET_SOCK_CREATE; attr.insns = insns; attr.insns_cnt = ARRAY_SIZE(insns); attr.license = "GPL"; return probe_fd(bpf_load_program_xattr(&attr, NULL, 0)); } static int probe_kern_probe_read_kernel(void) { struct bpf_load_program_attr attr; struct bpf_insn insns[] = { BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), /* r1 = r10 (fp) */ BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8), /* r1 += -8 */ BPF_MOV64_IMM(BPF_REG_2, 8), /* r2 = 8 */ BPF_MOV64_IMM(BPF_REG_3, 0), /* r3 = 0 */ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel), BPF_EXIT_INSN(), }; memset(&attr, 0, sizeof(attr)); attr.prog_type = BPF_PROG_TYPE_KPROBE; attr.insns = insns; attr.insns_cnt = ARRAY_SIZE(insns); attr.license = "GPL"; return probe_fd(bpf_load_program_xattr(&attr, NULL, 0)); } static int probe_prog_bind_map(void) { struct bpf_load_program_attr prg_attr; struct bpf_create_map_attr map_attr; char *cp, errmsg[STRERR_BUFSIZE]; struct bpf_insn insns[] = { BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }; int ret, map, prog; memset(&map_attr, 0, sizeof(map_attr)); map_attr.map_type = BPF_MAP_TYPE_ARRAY; map_attr.key_size = sizeof(int); map_attr.value_size = 32; map_attr.max_entries = 1; map = bpf_create_map_xattr(&map_attr); if (map < 0) { ret = -errno; cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", __func__, cp, -ret); return ret; } memset(&prg_attr, 0, sizeof(prg_attr)); prg_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER; prg_attr.insns = insns; prg_attr.insns_cnt = ARRAY_SIZE(insns); prg_attr.license = "GPL"; prog = bpf_load_program_xattr(&prg_attr, NULL, 0); if (prog < 0) { close(map); return 0; } ret = bpf_prog_bind_map(prog, map, NULL); close(map); close(prog); return ret >= 0; } static int probe_module_btf(void) { static const char strs[] = "\0int"; __u32 types[] = { /* int */ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), }; struct bpf_btf_info info; __u32 len = sizeof(info); char name[16]; int fd, err; fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs)); if (fd < 0) return 0; /* BTF not supported at all */ memset(&info, 0, sizeof(info)); info.name = ptr_to_u64(name); info.name_len = sizeof(name); /* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer; * kernel's module BTF support coincides with support for * name/name_len fields in struct bpf_btf_info. */ err = bpf_obj_get_info_by_fd(fd, &info, &len); close(fd); return !err; } enum kern_feature_result { FEAT_UNKNOWN = 0, FEAT_SUPPORTED = 1, FEAT_MISSING = 2, }; typedef int (*feature_probe_fn)(void); static struct kern_feature_desc { const char *desc; feature_probe_fn probe; enum kern_feature_result res; } feature_probes[__FEAT_CNT] = { [FEAT_PROG_NAME] = { "BPF program name", probe_kern_prog_name, }, [FEAT_GLOBAL_DATA] = { "global variables", probe_kern_global_data, }, [FEAT_BTF] = { "minimal BTF", probe_kern_btf, }, [FEAT_BTF_FUNC] = { "BTF functions", probe_kern_btf_func, }, [FEAT_BTF_GLOBAL_FUNC] = { "BTF global function", probe_kern_btf_func_global, }, [FEAT_BTF_DATASEC] = { "BTF data section and variable", probe_kern_btf_datasec, }, [FEAT_ARRAY_MMAP] = { "ARRAY map mmap()", probe_kern_array_mmap, }, [FEAT_EXP_ATTACH_TYPE] = { "BPF_PROG_LOAD expected_attach_type attribute", probe_kern_exp_attach_type, }, [FEAT_PROBE_READ_KERN] = { "bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel, }, [FEAT_PROG_BIND_MAP] = { "BPF_PROG_BIND_MAP support", probe_prog_bind_map, }, [FEAT_MODULE_BTF] = { "module BTF support", probe_module_btf, }, [FEAT_BTF_FLOAT] = { "BTF_KIND_FLOAT support", probe_kern_btf_float, }, }; static bool kernel_supports(enum kern_feature_id feat_id) { struct kern_feature_desc *feat = &feature_probes[feat_id]; int ret; if (READ_ONCE(feat->res) == FEAT_UNKNOWN) { ret = feat->probe(); if (ret > 0) { WRITE_ONCE(feat->res, FEAT_SUPPORTED); } else if (ret == 0) { WRITE_ONCE(feat->res, FEAT_MISSING); } else { pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret); WRITE_ONCE(feat->res, FEAT_MISSING); } } return READ_ONCE(feat->res) == FEAT_SUPPORTED; } static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd) { struct bpf_map_info map_info = {}; char msg[STRERR_BUFSIZE]; __u32 map_info_len; map_info_len = sizeof(map_info); if (bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len)) { pr_warn("failed to get map info for map FD %d: %s\n", map_fd, libbpf_strerror_r(errno, msg, sizeof(msg))); return false; } return (map_info.type == map->def.type && map_info.key_size == map->def.key_size && map_info.value_size == map->def.value_size && map_info.max_entries == map->def.max_entries && map_info.map_flags == map->def.map_flags); } static int bpf_object__reuse_map(struct bpf_map *map) { char *cp, errmsg[STRERR_BUFSIZE]; int err, pin_fd; pin_fd = bpf_obj_get(map->pin_path); if (pin_fd < 0) { err = -errno; if (err == -ENOENT) { pr_debug("found no pinned map to reuse at '%s'\n", map->pin_path); return 0; } cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg)); pr_warn("couldn't retrieve pinned map '%s': %s\n", map->pin_path, cp); return err; } if (!map_is_reuse_compat(map, pin_fd)) { pr_warn("couldn't reuse pinned map at '%s': parameter mismatch\n", map->pin_path); close(pin_fd); return -EINVAL; } err = bpf_map__reuse_fd(map, pin_fd); if (err) { close(pin_fd); return err; } map->pinned = true; pr_debug("reused pinned map at '%s'\n", map->pin_path); return 0; } static int bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map) { enum libbpf_map_type map_type = map->libbpf_type; char *cp, errmsg[STRERR_BUFSIZE]; int err, zero = 0; err = bpf_map_update_elem(map->fd, &zero, map->mmaped, 0); if (err) { err = -errno; cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg)); pr_warn("Error setting initial map(%s) contents: %s\n", map->name, cp); return err; } /* Freeze .rodata and .kconfig map as read-only from syscall side. */ if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG) { err = bpf_map_freeze(map->fd); if (err) { err = -errno; cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg)); pr_warn("Error freezing map(%s) as read-only: %s\n", map->name, cp); return err; } } return 0; } static void bpf_map__destroy(struct bpf_map *map); static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map) { struct bpf_create_map_attr create_attr; struct bpf_map_def *def = &map->def; memset(&create_attr, 0, sizeof(create_attr)); if (kernel_supports(FEAT_PROG_NAME)) create_attr.name = map->name; create_attr.map_ifindex = map->map_ifindex; create_attr.map_type = def->type; create_attr.map_flags = def->map_flags; create_attr.key_size = def->key_size; create_attr.value_size = def->value_size; create_attr.numa_node = map->numa_node; if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !def->max_entries) { int nr_cpus; nr_cpus = libbpf_num_possible_cpus(); if (nr_cpus < 0) { pr_warn("map '%s': failed to determine number of system CPUs: %d\n", map->name, nr_cpus); return nr_cpus; } pr_debug("map '%s': setting size to %d\n", map->name, nr_cpus); create_attr.max_entries = nr_cpus; } else { create_attr.max_entries = def->max_entries; } if (bpf_map__is_struct_ops(map)) create_attr.btf_vmlinux_value_type_id = map->btf_vmlinux_value_type_id; create_attr.btf_fd = 0; create_attr.btf_key_type_id = 0; create_attr.btf_value_type_id = 0; if (obj->btf && btf__fd(obj->btf) >= 0 && !bpf_map_find_btf_info(obj, map)) { create_attr.btf_fd = btf__fd(obj->btf); create_attr.btf_key_type_id = map->btf_key_type_id; create_attr.btf_value_type_id = map->btf_value_type_id; } if (bpf_map_type__is_map_in_map(def->type)) { if (map->inner_map) { int err; err = bpf_object__create_map(obj, map->inner_map); if (err) { pr_warn("map '%s': failed to create inner map: %d\n", map->name, err); return err; } map->inner_map_fd = bpf_map__fd(map->inner_map); } if (map->inner_map_fd >= 0) create_attr.inner_map_fd = map->inner_map_fd; } map->fd = bpf_create_map_xattr(&create_attr); if (map->fd < 0 && (create_attr.btf_key_type_id || create_attr.btf_value_type_id)) { char *cp, errmsg[STRERR_BUFSIZE]; int err = -errno; cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg)); pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n", map->name, cp, err); create_attr.btf_fd = 0; create_attr.btf_key_type_id = 0; create_attr.btf_value_type_id = 0; map->btf_key_type_id = 0; map->btf_value_type_id = 0; map->fd = bpf_create_map_xattr(&create_attr); } if (map->fd < 0) return -errno; if (bpf_map_type__is_map_in_map(def->type) && map->inner_map) { bpf_map__destroy(map->inner_map); zfree(&map->inner_map); } return 0; } static int init_map_slots(struct bpf_map *map) { const struct bpf_map *targ_map; unsigned int i; int fd, err; for (i = 0; i < map->init_slots_sz; i++) { if (!map->init_slots[i]) continue; targ_map = map->init_slots[i]; fd = bpf_map__fd(targ_map); err = bpf_map_update_elem(map->fd, &i, &fd, 0); if (err) { err = -errno; pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n", map->name, i, targ_map->name, fd, err); return err; } pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n", map->name, i, targ_map->name, fd); } zfree(&map->init_slots); map->init_slots_sz = 0; return 0; } static int bpf_object__create_maps(struct bpf_object *obj) { struct bpf_map *map; char *cp, errmsg[STRERR_BUFSIZE]; unsigned int i, j; int err; for (i = 0; i < obj->nr_maps; i++) { map = &obj->maps[i]; if (map->pin_path) { err = bpf_object__reuse_map(map); if (err) { pr_warn("map '%s': error reusing pinned map\n", map->name); goto err_out; } } if (map->fd >= 0) { pr_debug("map '%s': skipping creation (preset fd=%d)\n", map->name, map->fd); } else { err = bpf_object__create_map(obj, map); if (err) goto err_out; pr_debug("map '%s': created successfully, fd=%d\n", map->name, map->fd); if (bpf_map__is_internal(map)) { err = bpf_object__populate_internal_map(obj, map); if (err < 0) { zclose(map->fd); goto err_out; } } if (map->init_slots_sz) { err = init_map_slots(map); if (err < 0) { zclose(map->fd); goto err_out; } } } if (map->pin_path && !map->pinned) { err = bpf_map__pin(map, NULL); if (err) { pr_warn("map '%s': failed to auto-pin at '%s': %d\n", map->name, map->pin_path, err); zclose(map->fd); goto err_out; } } } return 0; err_out: cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg)); pr_warn("map '%s': failed to create: %s(%d)\n", map->name, cp, err); pr_perm_msg(err); for (j = 0; j < i; j++) zclose(obj->maps[j].fd); return err; } #define BPF_CORE_SPEC_MAX_LEN 64 /* represents BPF CO-RE field or array element accessor */ struct bpf_core_accessor { __u32 type_id; /* struct/union type or array element type */ __u32 idx; /* field index or array index */ const char *name; /* field name or NULL for array accessor */ }; struct bpf_core_spec { const struct btf *btf; /* high-level spec: named fields and array indices only */ struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN]; /* original unresolved (no skip_mods_or_typedefs) root type ID */ __u32 root_type_id; /* CO-RE relocation kind */ enum bpf_core_relo_kind relo_kind; /* high-level spec length */ int len; /* raw, low-level spec: 1-to-1 with accessor spec string */ int raw_spec[BPF_CORE_SPEC_MAX_LEN]; /* raw spec length */ int raw_len; /* field bit offset represented by spec */ __u32 bit_offset; }; static bool str_is_empty(const char *s) { return !s || !s[0]; } static bool is_flex_arr(const struct btf *btf, const struct bpf_core_accessor *acc, const struct btf_array *arr) { const struct btf_type *t; /* not a flexible array, if not inside a struct or has non-zero size */ if (!acc->name || arr->nelems > 0) return false; /* has to be the last member of enclosing struct */ t = btf__type_by_id(btf, acc->type_id); return acc->idx == btf_vlen(t) - 1; } static const char *core_relo_kind_str(enum bpf_core_relo_kind kind) { switch (kind) { case BPF_FIELD_BYTE_OFFSET: return "byte_off"; case BPF_FIELD_BYTE_SIZE: return "byte_sz"; case BPF_FIELD_EXISTS: return "field_exists"; case BPF_FIELD_SIGNED: return "signed"; case BPF_FIELD_LSHIFT_U64: return "lshift_u64"; case BPF_FIELD_RSHIFT_U64: return "rshift_u64"; case BPF_TYPE_ID_LOCAL: return "local_type_id"; case BPF_TYPE_ID_TARGET: return "target_type_id"; case BPF_TYPE_EXISTS: return "type_exists"; case BPF_TYPE_SIZE: return "type_size"; case BPF_ENUMVAL_EXISTS: return "enumval_exists"; case BPF_ENUMVAL_VALUE: return "enumval_value"; default: return "unknown"; } } static bool core_relo_is_field_based(enum bpf_core_relo_kind kind) { switch (kind) { case BPF_FIELD_BYTE_OFFSET: case BPF_FIELD_BYTE_SIZE: case BPF_FIELD_EXISTS: case BPF_FIELD_SIGNED: case BPF_FIELD_LSHIFT_U64: case BPF_FIELD_RSHIFT_U64: return true; default: return false; } } static bool core_relo_is_type_based(enum bpf_core_relo_kind kind) { switch (kind) { case BPF_TYPE_ID_LOCAL: case BPF_TYPE_ID_TARGET: case BPF_TYPE_EXISTS: case BPF_TYPE_SIZE: return true; default: return false; } } static bool core_relo_is_enumval_based(enum bpf_core_relo_kind kind) { switch (kind) { case BPF_ENUMVAL_EXISTS: case BPF_ENUMVAL_VALUE: return true; default: return false; } } /* * Turn bpf_core_relo into a low- and high-level spec representation, * validating correctness along the way, as well as calculating resulting * field bit offset, specified by accessor string. Low-level spec captures * every single level of nestedness, including traversing anonymous * struct/union members. High-level one only captures semantically meaningful * "turning points": named fields and array indicies. * E.g., for this case: * * struct sample { * int __unimportant; * struct { * int __1; * int __2; * int a[7]; * }; * }; * * struct sample *s = ...; * * int x = &s->a[3]; // access string = '0:1:2:3' * * Low-level spec has 1:1 mapping with each element of access string (it's * just a parsed access string representation): [0, 1, 2, 3]. * * High-level spec will capture only 3 points: * - intial zero-index access by pointer (&s->... is the same as &s[0]...); * - field 'a' access (corresponds to '2' in low-level spec); * - array element #3 access (corresponds to '3' in low-level spec). * * Type-based relocations (TYPE_EXISTS/TYPE_SIZE, * TYPE_ID_LOCAL/TYPE_ID_TARGET) don't capture any field information. Their * spec and raw_spec are kept empty. * * Enum value-based relocations (ENUMVAL_EXISTS/ENUMVAL_VALUE) use access * string to specify enumerator's value index that need to be relocated. */ static int bpf_core_parse_spec(const struct btf *btf, __u32 type_id, const char *spec_str, enum bpf_core_relo_kind relo_kind, struct bpf_core_spec *spec) { int access_idx, parsed_len, i; struct bpf_core_accessor *acc; const struct btf_type *t; const char *name; __u32 id; __s64 sz; if (str_is_empty(spec_str) || *spec_str == ':') return -EINVAL; memset(spec, 0, sizeof(*spec)); spec->btf = btf; spec->root_type_id = type_id; spec->relo_kind = relo_kind; /* type-based relocations don't have a field access string */ if (core_relo_is_type_based(relo_kind)) { if (strcmp(spec_str, "0")) return -EINVAL; return 0; } /* parse spec_str="0:1:2:3:4" into array raw_spec=[0, 1, 2, 3, 4] */ while (*spec_str) { if (*spec_str == ':') ++spec_str; if (sscanf(spec_str, "%d%n", &access_idx, &parsed_len) != 1) return -EINVAL; if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN) return -E2BIG; spec_str += parsed_len; spec->raw_spec[spec->raw_len++] = access_idx; } if (spec->raw_len == 0) return -EINVAL; t = skip_mods_and_typedefs(btf, type_id, &id); if (!t) return -EINVAL; access_idx = spec->raw_spec[0]; acc = &spec->spec[0]; acc->type_id = id; acc->idx = access_idx; spec->len++; if (core_relo_is_enumval_based(relo_kind)) { if (!btf_is_enum(t) || spec->raw_len > 1 || access_idx >= btf_vlen(t)) return -EINVAL; /* record enumerator name in a first accessor */ acc->name = btf__name_by_offset(btf, btf_enum(t)[access_idx].name_off); return 0; } if (!core_relo_is_field_based(relo_kind)) return -EINVAL; sz = btf__resolve_size(btf, id); if (sz < 0) return sz; spec->bit_offset = access_idx * sz * 8; for (i = 1; i < spec->raw_len; i++) { t = skip_mods_and_typedefs(btf, id, &id); if (!t) return -EINVAL; access_idx = spec->raw_spec[i]; acc = &spec->spec[spec->len]; if (btf_is_composite(t)) { const struct btf_member *m; __u32 bit_offset; if (access_idx >= btf_vlen(t)) return -EINVAL; bit_offset = btf_member_bit_offset(t, access_idx); spec->bit_offset += bit_offset; m = btf_members(t) + access_idx; if (m->name_off) { name = btf__name_by_offset(btf, m->name_off); if (str_is_empty(name)) return -EINVAL; acc->type_id = id; acc->idx = access_idx; acc->name = name; spec->len++; } id = m->type; } else if (btf_is_array(t)) { const struct btf_array *a = btf_array(t); bool flex; t = skip_mods_and_typedefs(btf, a->type, &id); if (!t) return -EINVAL; flex = is_flex_arr(btf, acc - 1, a); if (!flex && access_idx >= a->nelems) return -EINVAL; spec->spec[spec->len].type_id = id; spec->spec[spec->len].idx = access_idx; spec->len++; sz = btf__resolve_size(btf, id); if (sz < 0) return sz; spec->bit_offset += access_idx * sz * 8; } else { pr_warn("relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %s\n", type_id, spec_str, i, id, btf_kind_str(t)); return -EINVAL; } } return 0; } static bool bpf_core_is_flavor_sep(const char *s) { /* check X___Y name pattern, where X and Y are not underscores */ return s[0] != '_' && /* X */ s[1] == '_' && s[2] == '_' && s[3] == '_' && /* ___ */ s[4] != '_'; /* Y */ } /* Given 'some_struct_name___with_flavor' return the length of a name prefix * before last triple underscore. Struct name part after last triple * underscore is ignored by BPF CO-RE relocation during relocation matching. */ static size_t bpf_core_essential_name_len(const char *name) { size_t n = strlen(name); int i; for (i = n - 5; i >= 0; i--) { if (bpf_core_is_flavor_sep(name + i)) return i + 1; } return n; } struct core_cand { const struct btf *btf; const struct btf_type *t; const char *name; __u32 id; }; /* dynamically sized list of type IDs and its associated struct btf */ struct core_cand_list { struct core_cand *cands; int len; }; static void bpf_core_free_cands(struct core_cand_list *cands) { free(cands->cands); free(cands); } static int bpf_core_add_cands(struct core_cand *local_cand, size_t local_essent_len, const struct btf *targ_btf, const char *targ_btf_name, int targ_start_id, struct core_cand_list *cands) { struct core_cand *new_cands, *cand; const struct btf_type *t; const char *targ_name; size_t targ_essent_len; int n, i; n = btf__get_nr_types(targ_btf); for (i = targ_start_id; i <= n; i++) { t = btf__type_by_id(targ_btf, i); if (btf_kind(t) != btf_kind(local_cand->t)) continue; targ_name = btf__name_by_offset(targ_btf, t->name_off); if (str_is_empty(targ_name)) continue; targ_essent_len = bpf_core_essential_name_len(targ_name); if (targ_essent_len != local_essent_len) continue; if (strncmp(local_cand->name, targ_name, local_essent_len) != 0) continue; pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s in [%s]\n", local_cand->id, btf_kind_str(local_cand->t), local_cand->name, i, btf_kind_str(t), targ_name, targ_btf_name); new_cands = libbpf_reallocarray(cands->cands, cands->len + 1, sizeof(*cands->cands)); if (!new_cands) return -ENOMEM; cand = &new_cands[cands->len]; cand->btf = targ_btf; cand->t = t; cand->name = targ_name; cand->id = i; cands->cands = new_cands; cands->len++; } return 0; } static int load_module_btfs(struct bpf_object *obj) { struct bpf_btf_info info; struct module_btf *mod_btf; struct btf *btf; char name[64]; __u32 id = 0, len; int err, fd; if (obj->btf_modules_loaded) return 0; /* don't do this again, even if we find no module BTFs */ obj->btf_modules_loaded = true; /* kernel too old to support module BTFs */ if (!kernel_supports(FEAT_MODULE_BTF)) return 0; while (true) { err = bpf_btf_get_next_id(id, &id); if (err && errno == ENOENT) return 0; if (err) { err = -errno; pr_warn("failed to iterate BTF objects: %d\n", err); return err; } fd = bpf_btf_get_fd_by_id(id); if (fd < 0) { if (errno == ENOENT) continue; /* expected race: BTF was unloaded */ err = -errno; pr_warn("failed to get BTF object #%d FD: %d\n", id, err); return err; } len = sizeof(info); memset(&info, 0, sizeof(info)); info.name = ptr_to_u64(name); info.name_len = sizeof(name); err = bpf_obj_get_info_by_fd(fd, &info, &len); if (err) { err = -errno; pr_warn("failed to get BTF object #%d info: %d\n", id, err); goto err_out; } /* ignore non-module BTFs */ if (!info.kernel_btf || strcmp(name, "vmlinux") == 0) { close(fd); continue; } btf = btf_get_from_fd(fd, obj->btf_vmlinux); if (IS_ERR(btf)) { pr_warn("failed to load module [%s]'s BTF object #%d: %ld\n", name, id, PTR_ERR(btf)); err = PTR_ERR(btf); goto err_out; } err = libbpf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap, sizeof(*obj->btf_modules), obj->btf_module_cnt + 1); if (err) goto err_out; mod_btf = &obj->btf_modules[obj->btf_module_cnt++]; mod_btf->btf = btf; mod_btf->id = id; mod_btf->fd = fd; mod_btf->name = strdup(name); if (!mod_btf->name) { err = -ENOMEM; goto err_out; } continue; err_out: close(fd); return err; } return 0; } static struct core_cand_list * bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id) { struct core_cand local_cand = {}; struct core_cand_list *cands; const struct btf *main_btf; size_t local_essent_len; int err, i; local_cand.btf = local_btf; local_cand.t = btf__type_by_id(local_btf, local_type_id); if (!local_cand.t) return ERR_PTR(-EINVAL); local_cand.name = btf__name_by_offset(local_btf, local_cand.t->name_off); if (str_is_empty(local_cand.name)) return ERR_PTR(-EINVAL); local_essent_len = bpf_core_essential_name_len(local_cand.name); cands = calloc(1, sizeof(*cands)); if (!cands) return ERR_PTR(-ENOMEM); /* Attempt to find target candidates in vmlinux BTF first */ main_btf = obj->btf_vmlinux_override ?: obj->btf_vmlinux; err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, "vmlinux", 1, cands); if (err) goto err_out; /* if vmlinux BTF has any candidate, don't got for module BTFs */ if (cands->len) return cands; /* if vmlinux BTF was overridden, don't attempt to load module BTFs */ if (obj->btf_vmlinux_override) return cands; /* now look through module BTFs, trying to still find candidates */ err = load_module_btfs(obj); if (err) goto err_out; for (i = 0; i < obj->btf_module_cnt; i++) { err = bpf_core_add_cands(&local_cand, local_essent_len, obj->btf_modules[i].btf, obj->btf_modules[i].name, btf__get_nr_types(obj->btf_vmlinux) + 1, cands); if (err) goto err_out; } return cands; err_out: bpf_core_free_cands(cands); return ERR_PTR(err); } /* Check two types for compatibility for the purpose of field access * relocation. const/volatile/restrict and typedefs are skipped to ensure we * are relocating semantically compatible entities: * - any two STRUCTs/UNIONs are compatible and can be mixed; * - any two FWDs are compatible, if their names match (modulo flavor suffix); * - any two PTRs are always compatible; * - for ENUMs, names should be the same (ignoring flavor suffix) or at * least one of enums should be anonymous; * - for ENUMs, check sizes, names are ignored; * - for INT, size and signedness are ignored; * - any two FLOATs are always compatible; * - for ARRAY, dimensionality is ignored, element types are checked for * compatibility recursively; * - everything else shouldn't be ever a target of relocation. * These rules are not set in stone and probably will be adjusted as we get * more experience with using BPF CO-RE relocations. */ static int bpf_core_fields_are_compat(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf, __u32 targ_id) { const struct btf_type *local_type, *targ_type; recur: local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id); targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id); if (!local_type || !targ_type) return -EINVAL; if (btf_is_composite(local_type) && btf_is_composite(targ_type)) return 1; if (btf_kind(local_type) != btf_kind(targ_type)) return 0; switch (btf_kind(local_type)) { case BTF_KIND_PTR: case BTF_KIND_FLOAT: return 1; case BTF_KIND_FWD: case BTF_KIND_ENUM: { const char *local_name, *targ_name; size_t local_len, targ_len; local_name = btf__name_by_offset(local_btf, local_type->name_off); targ_name = btf__name_by_offset(targ_btf, targ_type->name_off); local_len = bpf_core_essential_name_len(local_name); targ_len = bpf_core_essential_name_len(targ_name); /* one of them is anonymous or both w/ same flavor-less names */ return local_len == 0 || targ_len == 0 || (local_len == targ_len && strncmp(local_name, targ_name, local_len) == 0); } case BTF_KIND_INT: /* just reject deprecated bitfield-like integers; all other * integers are by default compatible between each other */ return btf_int_offset(local_type) == 0 && btf_int_offset(targ_type) == 0; case BTF_KIND_ARRAY: local_id = btf_array(local_type)->type; targ_id = btf_array(targ_type)->type; goto recur; default: pr_warn("unexpected kind %d relocated, local [%d], target [%d]\n", btf_kind(local_type), local_id, targ_id); return 0; } } /* * Given single high-level named field accessor in local type, find * corresponding high-level accessor for a target type. Along the way, * maintain low-level spec for target as well. Also keep updating target * bit offset. * * Searching is performed through recursive exhaustive enumeration of all * fields of a struct/union. If there are any anonymous (embedded) * structs/unions, they are recursively searched as well. If field with * desired name is found, check compatibility between local and target types, * before returning result. * * 1 is returned, if field is found. * 0 is returned if no compatible field is found. * <0 is returned on error. */ static int bpf_core_match_member(const struct btf *local_btf, const struct bpf_core_accessor *local_acc, const struct btf *targ_btf, __u32 targ_id, struct bpf_core_spec *spec, __u32 *next_targ_id) { const struct btf_type *local_type, *targ_type; const struct btf_member *local_member, *m; const char *local_name, *targ_name; __u32 local_id; int i, n, found; targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id); if (!targ_type) return -EINVAL; if (!btf_is_composite(targ_type)) return 0; local_id = local_acc->type_id; local_type = btf__type_by_id(local_btf, local_id); local_member = btf_members(local_type) + local_acc->idx; local_name = btf__name_by_offset(local_btf, local_member->name_off); n = btf_vlen(targ_type); m = btf_members(targ_type); for (i = 0; i < n; i++, m++) { __u32 bit_offset; bit_offset = btf_member_bit_offset(targ_type, i); /* too deep struct/union/array nesting */ if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN) return -E2BIG; /* speculate this member will be the good one */ spec->bit_offset += bit_offset; spec->raw_spec[spec->raw_len++] = i; targ_name = btf__name_by_offset(targ_btf, m->name_off); if (str_is_empty(targ_name)) { /* embedded struct/union, we need to go deeper */ found = bpf_core_match_member(local_btf, local_acc, targ_btf, m->type, spec, next_targ_id); if (found) /* either found or error */ return found; } else if (strcmp(local_name, targ_name) == 0) { /* matching named field */ struct bpf_core_accessor *targ_acc; targ_acc = &spec->spec[spec->len++]; targ_acc->type_id = targ_id; targ_acc->idx = i; targ_acc->name = targ_name; *next_targ_id = m->type; found = bpf_core_fields_are_compat(local_btf, local_member->type, targ_btf, m->type); if (!found) spec->len--; /* pop accessor */ return found; } /* member turned out not to be what we looked for */ spec->bit_offset -= bit_offset; spec->raw_len--; } return 0; } /* Check local and target types for compatibility. This check is used for * type-based CO-RE relocations and follow slightly different rules than * field-based relocations. This function assumes that root types were already * checked for name match. Beyond that initial root-level name check, names * are completely ignored. Compatibility rules are as follows: * - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs are considered compatible, but * kind should match for local and target types (i.e., STRUCT is not * compatible with UNION); * - for ENUMs, the size is ignored; * - for INT, size and signedness are ignored; * - for ARRAY, dimensionality is ignored, element types are checked for * compatibility recursively; * - CONST/VOLATILE/RESTRICT modifiers are ignored; * - TYPEDEFs/PTRs are compatible if types they pointing to are compatible; * - FUNC_PROTOs are compatible if they have compatible signature: same * number of input args and compatible return and argument types. * These rules are not set in stone and probably will be adjusted as we get * more experience with using BPF CO-RE relocations. */ static int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf, __u32 targ_id) { const struct btf_type *local_type, *targ_type; int depth = 32; /* max recursion depth */ /* caller made sure that names match (ignoring flavor suffix) */ local_type = btf__type_by_id(local_btf, local_id); targ_type = btf__type_by_id(targ_btf, targ_id); if (btf_kind(local_type) != btf_kind(targ_type)) return 0; recur: depth--; if (depth < 0) return -EINVAL; local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id); targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id); if (!local_type || !targ_type) return -EINVAL; if (btf_kind(local_type) != btf_kind(targ_type)) return 0; switch (btf_kind(local_type)) { case BTF_KIND_UNKN: case BTF_KIND_STRUCT: case BTF_KIND_UNION: case BTF_KIND_ENUM: case BTF_KIND_FWD: return 1; case BTF_KIND_INT: /* just reject deprecated bitfield-like integers; all other * integers are by default compatible between each other */ return btf_int_offset(local_type) == 0 && btf_int_offset(targ_type) == 0; case BTF_KIND_PTR: local_id = local_type->type; targ_id = targ_type->type; goto recur; case BTF_KIND_ARRAY: local_id = btf_array(local_type)->type; targ_id = btf_array(targ_type)->type; goto recur; case BTF_KIND_FUNC_PROTO: { struct btf_param *local_p = btf_params(local_type); struct btf_param *targ_p = btf_params(targ_type); __u16 local_vlen = btf_vlen(local_type); __u16 targ_vlen = btf_vlen(targ_type); int i, err; if (local_vlen != targ_vlen) return 0; for (i = 0; i < local_vlen; i++, local_p++, targ_p++) { skip_mods_and_typedefs(local_btf, local_p->type, &local_id); skip_mods_and_typedefs(targ_btf, targ_p->type, &targ_id); err = bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id); if (err <= 0) return err; } /* tail recurse for return type check */ skip_mods_and_typedefs(local_btf, local_type->type, &local_id); skip_mods_and_typedefs(targ_btf, targ_type->type, &targ_id); goto recur; } default: pr_warn("unexpected kind %s relocated, local [%d], target [%d]\n", btf_kind_str(local_type), local_id, targ_id); return 0; } } /* * Try to match local spec to a target type and, if successful, produce full * target spec (high-level, low-level + bit offset). */ static int bpf_core_spec_match(struct bpf_core_spec *local_spec, const struct btf *targ_btf, __u32 targ_id, struct bpf_core_spec *targ_spec) { const struct btf_type *targ_type; const struct bpf_core_accessor *local_acc; struct bpf_core_accessor *targ_acc; int i, sz, matched; memset(targ_spec, 0, sizeof(*targ_spec)); targ_spec->btf = targ_btf; targ_spec->root_type_id = targ_id; targ_spec->relo_kind = local_spec->relo_kind; if (core_relo_is_type_based(local_spec->relo_kind)) { return bpf_core_types_are_compat(local_spec->btf, local_spec->root_type_id, targ_btf, targ_id); } local_acc = &local_spec->spec[0]; targ_acc = &targ_spec->spec[0]; if (core_relo_is_enumval_based(local_spec->relo_kind)) { size_t local_essent_len, targ_essent_len; const struct btf_enum *e; const char *targ_name; /* has to resolve to an enum */ targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id, &targ_id); if (!btf_is_enum(targ_type)) return 0; local_essent_len = bpf_core_essential_name_len(local_acc->name); for (i = 0, e = btf_enum(targ_type); i < btf_vlen(targ_type); i++, e++) { targ_name = btf__name_by_offset(targ_spec->btf, e->name_off); targ_essent_len = bpf_core_essential_name_len(targ_name); if (targ_essent_len != local_essent_len) continue; if (strncmp(local_acc->name, targ_name, local_essent_len) == 0) { targ_acc->type_id = targ_id; targ_acc->idx = i; targ_acc->name = targ_name; targ_spec->len++; targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx; targ_spec->raw_len++; return 1; } } return 0; } if (!core_relo_is_field_based(local_spec->relo_kind)) return -EINVAL; for (i = 0; i < local_spec->len; i++, local_acc++, targ_acc++) { targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id, &targ_id); if (!targ_type) return -EINVAL; if (local_acc->name) { matched = bpf_core_match_member(local_spec->btf, local_acc, targ_btf, targ_id, targ_spec, &targ_id); if (matched <= 0) return matched; } else { /* for i=0, targ_id is already treated as array element * type (because it's the original struct), for others * we should find array element type first */ if (i > 0) { const struct btf_array *a; bool flex; if (!btf_is_array(targ_type)) return 0; a = btf_array(targ_type); flex = is_flex_arr(targ_btf, targ_acc - 1, a); if (!flex && local_acc->idx >= a->nelems) return 0; if (!skip_mods_and_typedefs(targ_btf, a->type, &targ_id)) return -EINVAL; } /* too deep struct/union/array nesting */ if (targ_spec->raw_len == BPF_CORE_SPEC_MAX_LEN) return -E2BIG; targ_acc->type_id = targ_id; targ_acc->idx = local_acc->idx; targ_acc->name = NULL; targ_spec->len++; targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx; targ_spec->raw_len++; sz = btf__resolve_size(targ_btf, targ_id); if (sz < 0) return sz; targ_spec->bit_offset += local_acc->idx * sz * 8; } } return 1; } static int bpf_core_calc_field_relo(const struct bpf_program *prog, const struct bpf_core_relo *relo, const struct bpf_core_spec *spec, __u32 *val, __u32 *field_sz, __u32 *type_id, bool *validate) { const struct bpf_core_accessor *acc; const struct btf_type *t; __u32 byte_off, byte_sz, bit_off, bit_sz, field_type_id; const struct btf_member *m; const struct btf_type *mt; bool bitfield; __s64 sz; *field_sz = 0; if (relo->kind == BPF_FIELD_EXISTS) { *val = spec ? 1 : 0; return 0; } if (!spec) return -EUCLEAN; /* request instruction poisoning */ acc = &spec->spec[spec->len - 1]; t = btf__type_by_id(spec->btf, acc->type_id); /* a[n] accessor needs special handling */ if (!acc->name) { if (relo->kind == BPF_FIELD_BYTE_OFFSET) { *val = spec->bit_offset / 8; /* remember field size for load/store mem size */ sz = btf__resolve_size(spec->btf, acc->type_id); if (sz < 0) return -EINVAL; *field_sz = sz; *type_id = acc->type_id; } else if (relo->kind == BPF_FIELD_BYTE_SIZE) { sz = btf__resolve_size(spec->btf, acc->type_id); if (sz < 0) return -EINVAL; *val = sz; } else { pr_warn("prog '%s': relo %d at insn #%d can't be applied to array access\n", prog->name, relo->kind, relo->insn_off / 8); return -EINVAL; } if (validate) *validate = true; return 0; } m = btf_members(t) + acc->idx; mt = skip_mods_and_typedefs(spec->btf, m->type, &field_type_id); bit_off = spec->bit_offset; bit_sz = btf_member_bitfield_size(t, acc->idx); bitfield = bit_sz > 0; if (bitfield) { byte_sz = mt->size; byte_off = bit_off / 8 / byte_sz * byte_sz; /* figure out smallest int size necessary for bitfield load */ while (bit_off + bit_sz - byte_off * 8 > byte_sz * 8) { if (byte_sz >= 8) { /* bitfield can't be read with 64-bit read */ pr_warn("prog '%s': relo %d at insn #%d can't be satisfied for bitfield\n", prog->name, relo->kind, relo->insn_off / 8); return -E2BIG; } byte_sz *= 2; byte_off = bit_off / 8 / byte_sz * byte_sz; } } else { sz = btf__resolve_size(spec->btf, field_type_id); if (sz < 0) return -EINVAL; byte_sz = sz; byte_off = spec->bit_offset / 8; bit_sz = byte_sz * 8; } /* for bitfields, all the relocatable aspects are ambiguous and we * might disagree with compiler, so turn off validation of expected * value, except for signedness */ if (validate) *validate = !bitfield; switch (relo->kind) { case BPF_FIELD_BYTE_OFFSET: *val = byte_off; if (!bitfield) { *field_sz = byte_sz; *type_id = field_type_id; } break; case BPF_FIELD_BYTE_SIZE: *val = byte_sz; break; case BPF_FIELD_SIGNED: /* enums will be assumed unsigned */ *val = btf_is_enum(mt) || (btf_int_encoding(mt) & BTF_INT_SIGNED); if (validate) *validate = true; /* signedness is never ambiguous */ break; case BPF_FIELD_LSHIFT_U64: #if __BYTE_ORDER == __LITTLE_ENDIAN *val = 64 - (bit_off + bit_sz - byte_off * 8); #else *val = (8 - byte_sz) * 8 + (bit_off - byte_off * 8); #endif break; case BPF_FIELD_RSHIFT_U64: *val = 64 - bit_sz; if (validate) *validate = true; /* right shift is never ambiguous */ break; case BPF_FIELD_EXISTS: default: return -EOPNOTSUPP; } return 0; } static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo, const struct bpf_core_spec *spec, __u32 *val) { __s64 sz; /* type-based relos return zero when target type is not found */ if (!spec) { *val = 0; return 0; } switch (relo->kind) { case BPF_TYPE_ID_TARGET: *val = spec->root_type_id; break; case BPF_TYPE_EXISTS: *val = 1; break; case BPF_TYPE_SIZE: sz = btf__resolve_size(spec->btf, spec->root_type_id); if (sz < 0) return -EINVAL; *val = sz; break; case BPF_TYPE_ID_LOCAL: /* BPF_TYPE_ID_LOCAL is handled specially and shouldn't get here */ default: return -EOPNOTSUPP; } return 0; } static int bpf_core_calc_enumval_relo(const struct bpf_core_relo *relo, const struct bpf_core_spec *spec, __u32 *val) { const struct btf_type *t; const struct btf_enum *e; switch (relo->kind) { case BPF_ENUMVAL_EXISTS: *val = spec ? 1 : 0; break; case BPF_ENUMVAL_VALUE: if (!spec) return -EUCLEAN; /* request instruction poisoning */ t = btf__type_by_id(spec->btf, spec->spec[0].type_id); e = btf_enum(t) + spec->spec[0].idx; *val = e->val; break; default: return -EOPNOTSUPP; } return 0; } struct bpf_core_relo_res { /* expected value in the instruction, unless validate == false */ __u32 orig_val; /* new value that needs to be patched up to */ __u32 new_val; /* relocation unsuccessful, poison instruction, but don't fail load */ bool poison; /* some relocations can't be validated against orig_val */ bool validate; /* for field byte offset relocations or the forms: * *(T *)(rX + ) = rY * rX = *(T *)(rY + ), * we remember original and resolved field size to adjust direct * memory loads of pointers and integers; this is necessary for 32-bit * host kernel architectures, but also allows to automatically * relocate fields that were resized from, e.g., u32 to u64, etc. */ bool fail_memsz_adjust; __u32 orig_sz; __u32 orig_type_id; __u32 new_sz; __u32 new_type_id; }; /* Calculate original and target relocation values, given local and target * specs and relocation kind. These values are calculated for each candidate. * If there are multiple candidates, resulting values should all be consistent * with each other. Otherwise, libbpf will refuse to proceed due to ambiguity. * If instruction has to be poisoned, *poison will be set to true. */ static int bpf_core_calc_relo(const struct bpf_program *prog, const struct bpf_core_relo *relo, int relo_idx, const struct bpf_core_spec *local_spec, const struct bpf_core_spec *targ_spec, struct bpf_core_relo_res *res) { int err = -EOPNOTSUPP; res->orig_val = 0; res->new_val = 0; res->poison = false; res->validate = true; res->fail_memsz_adjust = false; res->orig_sz = res->new_sz = 0; res->orig_type_id = res->new_type_id = 0; if (core_relo_is_field_based(relo->kind)) { err = bpf_core_calc_field_relo(prog, relo, local_spec, &res->orig_val, &res->orig_sz, &res->orig_type_id, &res->validate); err = err ?: bpf_core_calc_field_relo(prog, relo, targ_spec, &res->new_val, &res->new_sz, &res->new_type_id, NULL); if (err) goto done; /* Validate if it's safe to adjust load/store memory size. * Adjustments are performed only if original and new memory * sizes differ. */ res->fail_memsz_adjust = false; if (res->orig_sz != res->new_sz) { const struct btf_type *orig_t, *new_t; orig_t = btf__type_by_id(local_spec->btf, res->orig_type_id); new_t = btf__type_by_id(targ_spec->btf, res->new_type_id); /* There are two use cases in which it's safe to * adjust load/store's mem size: * - reading a 32-bit kernel pointer, while on BPF * size pointers are always 64-bit; in this case * it's safe to "downsize" instruction size due to * pointer being treated as unsigned integer with * zero-extended upper 32-bits; * - reading unsigned integers, again due to * zero-extension is preserving the value correctly. * * In all other cases it's incorrect to attempt to * load/store field because read value will be * incorrect, so we poison relocated instruction. */ if (btf_is_ptr(orig_t) && btf_is_ptr(new_t)) goto done; if (btf_is_int(orig_t) && btf_is_int(new_t) && btf_int_encoding(orig_t) != BTF_INT_SIGNED && btf_int_encoding(new_t) != BTF_INT_SIGNED) goto done; /* mark as invalid mem size adjustment, but this will * only be checked for LDX/STX/ST insns */ res->fail_memsz_adjust = true; } } else if (core_relo_is_type_based(relo->kind)) { err = bpf_core_calc_type_relo(relo, local_spec, &res->orig_val); err = err ?: bpf_core_calc_type_relo(relo, targ_spec, &res->new_val); } else if (core_relo_is_enumval_based(relo->kind)) { err = bpf_core_calc_enumval_relo(relo, local_spec, &res->orig_val); err = err ?: bpf_core_calc_enumval_relo(relo, targ_spec, &res->new_val); } done: if (err == -EUCLEAN) { /* EUCLEAN is used to signal instruction poisoning request */ res->poison = true; err = 0; } else if (err == -EOPNOTSUPP) { /* EOPNOTSUPP means unknown/unsupported relocation */ pr_warn("prog '%s': relo #%d: unrecognized CO-RE relocation %s (%d) at insn #%d\n", prog->name, relo_idx, core_relo_kind_str(relo->kind), relo->kind, relo->insn_off / 8); } return err; } /* * Turn instruction for which CO_RE relocation failed into invalid one with * distinct signature. */ static void bpf_core_poison_insn(struct bpf_program *prog, int relo_idx, int insn_idx, struct bpf_insn *insn) { pr_debug("prog '%s': relo #%d: substituting insn #%d w/ invalid insn\n", prog->name, relo_idx, insn_idx); insn->code = BPF_JMP | BPF_CALL; insn->dst_reg = 0; insn->src_reg = 0; insn->off = 0; /* if this instruction is reachable (not a dead code), * verifier will complain with the following message: * invalid func unknown#195896080 */ insn->imm = 195896080; /* => 0xbad2310 => "bad relo" */ } static int insn_bpf_size_to_bytes(struct bpf_insn *insn) { switch (BPF_SIZE(insn->code)) { case BPF_DW: return 8; case BPF_W: return 4; case BPF_H: return 2; case BPF_B: return 1; default: return -1; } } static int insn_bytes_to_bpf_size(__u32 sz) { switch (sz) { case 8: return BPF_DW; case 4: return BPF_W; case 2: return BPF_H; case 1: return BPF_B; default: return -1; } } /* * Patch relocatable BPF instruction. * * Patched value is determined by relocation kind and target specification. * For existence relocations target spec will be NULL if field/type is not found. * Expected insn->imm value is determined using relocation kind and local * spec, and is checked before patching instruction. If actual insn->imm value * is wrong, bail out with error. * * Currently supported classes of BPF instruction are: * 1. rX = (assignment with immediate operand); * 2. rX += (arithmetic operations with immediate operand); * 3. rX = (load with 64-bit immediate value); * 4. rX = *(T *)(rY + ), where T is one of {u8, u16, u32, u64}; * 5. *(T *)(rX + ) = rY, where T is one of {u8, u16, u32, u64}; * 6. *(T *)(rX + ) = , where T is one of {u8, u16, u32, u64}. */ static int bpf_core_patch_insn(struct bpf_program *prog, const struct bpf_core_relo *relo, int relo_idx, const struct bpf_core_relo_res *res) { __u32 orig_val, new_val; struct bpf_insn *insn; int insn_idx; __u8 class; if (relo->insn_off % BPF_INSN_SZ) return -EINVAL; insn_idx = relo->insn_off / BPF_INSN_SZ; /* adjust insn_idx from section frame of reference to the local * program's frame of reference; (sub-)program code is not yet * relocated, so it's enough to just subtract in-section offset */ insn_idx = insn_idx - prog->sec_insn_off; insn = &prog->insns[insn_idx]; class = BPF_CLASS(insn->code); if (res->poison) { poison: /* poison second part of ldimm64 to avoid confusing error from * verifier about "unknown opcode 00" */ if (is_ldimm64_insn(insn)) bpf_core_poison_insn(prog, relo_idx, insn_idx + 1, insn + 1); bpf_core_poison_insn(prog, relo_idx, insn_idx, insn); return 0; } orig_val = res->orig_val; new_val = res->new_val; switch (class) { case BPF_ALU: case BPF_ALU64: if (BPF_SRC(insn->code) != BPF_K) return -EINVAL; if (res->validate && insn->imm != orig_val) { pr_warn("prog '%s': relo #%d: unexpected insn #%d (ALU/ALU64) value: got %u, exp %u -> %u\n", prog->name, relo_idx, insn_idx, insn->imm, orig_val, new_val); return -EINVAL; } orig_val = insn->imm; insn->imm = new_val; pr_debug("prog '%s': relo #%d: patched insn #%d (ALU/ALU64) imm %u -> %u\n", prog->name, relo_idx, insn_idx, orig_val, new_val); break; case BPF_LDX: case BPF_ST: case BPF_STX: if (res->validate && insn->off != orig_val) { pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDX/ST/STX) value: got %u, exp %u -> %u\n", prog->name, relo_idx, insn_idx, insn->off, orig_val, new_val); return -EINVAL; } if (new_val > SHRT_MAX) { pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) value too big: %u\n", prog->name, relo_idx, insn_idx, new_val); return -ERANGE; } if (res->fail_memsz_adjust) { pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) accesses field incorrectly. " "Make sure you are accessing pointers, unsigned integers, or fields of matching type and size.\n", prog->name, relo_idx, insn_idx); goto poison; } orig_val = insn->off; insn->off = new_val; pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) off %u -> %u\n", prog->name, relo_idx, insn_idx, orig_val, new_val); if (res->new_sz != res->orig_sz) { int insn_bytes_sz, insn_bpf_sz; insn_bytes_sz = insn_bpf_size_to_bytes(insn); if (insn_bytes_sz != res->orig_sz) { pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) unexpected mem size: got %d, exp %u\n", prog->name, relo_idx, insn_idx, insn_bytes_sz, res->orig_sz); return -EINVAL; } insn_bpf_sz = insn_bytes_to_bpf_size(res->new_sz); if (insn_bpf_sz < 0) { pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) invalid new mem size: %u\n", prog->name, relo_idx, insn_idx, res->new_sz); return -EINVAL; } insn->code = BPF_MODE(insn->code) | insn_bpf_sz | BPF_CLASS(insn->code); pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) mem_sz %u -> %u\n", prog->name, relo_idx, insn_idx, res->orig_sz, res->new_sz); } break; case BPF_LD: { __u64 imm; if (!is_ldimm64_insn(insn) || insn[0].src_reg != 0 || insn[0].off != 0 || insn_idx + 1 >= prog->insns_cnt || insn[1].code != 0 || insn[1].dst_reg != 0 || insn[1].src_reg != 0 || insn[1].off != 0) { pr_warn("prog '%s': relo #%d: insn #%d (LDIMM64) has unexpected form\n", prog->name, relo_idx, insn_idx); return -EINVAL; } imm = insn[0].imm + ((__u64)insn[1].imm << 32); if (res->validate && imm != orig_val) { pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %u -> %u\n", prog->name, relo_idx, insn_idx, (unsigned long long)imm, orig_val, new_val); return -EINVAL; } insn[0].imm = new_val; insn[1].imm = 0; /* currently only 32-bit values are supported */ pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %u\n", prog->name, relo_idx, insn_idx, (unsigned long long)imm, new_val); break; } default: pr_warn("prog '%s': relo #%d: trying to relocate unrecognized insn #%d, code:0x%x, src:0x%x, dst:0x%x, off:0x%x, imm:0x%x\n", prog->name, relo_idx, insn_idx, insn->code, insn->src_reg, insn->dst_reg, insn->off, insn->imm); return -EINVAL; } return 0; } /* Output spec definition in the format: * [] () + => @, * where is a C-syntax view of recorded field access, e.g.: x.a[3].b */ static void bpf_core_dump_spec(int level, const struct bpf_core_spec *spec) { const struct btf_type *t; const struct btf_enum *e; const char *s; __u32 type_id; int i; type_id = spec->root_type_id; t = btf__type_by_id(spec->btf, type_id); s = btf__name_by_offset(spec->btf, t->name_off); libbpf_print(level, "[%u] %s %s", type_id, btf_kind_str(t), str_is_empty(s) ? "" : s); if (core_relo_is_type_based(spec->relo_kind)) return; if (core_relo_is_enumval_based(spec->relo_kind)) { t = skip_mods_and_typedefs(spec->btf, type_id, NULL); e = btf_enum(t) + spec->raw_spec[0]; s = btf__name_by_offset(spec->btf, e->name_off); libbpf_print(level, "::%s = %u", s, e->val); return; } if (core_relo_is_field_based(spec->relo_kind)) { for (i = 0; i < spec->len; i++) { if (spec->spec[i].name) libbpf_print(level, ".%s", spec->spec[i].name); else if (i > 0 || spec->spec[i].idx > 0) libbpf_print(level, "[%u]", spec->spec[i].idx); } libbpf_print(level, " ("); for (i = 0; i < spec->raw_len; i++) libbpf_print(level, "%s%d", i == 0 ? "" : ":", spec->raw_spec[i]); if (spec->bit_offset % 8) libbpf_print(level, " @ offset %u.%u)", spec->bit_offset / 8, spec->bit_offset % 8); else libbpf_print(level, " @ offset %u)", spec->bit_offset / 8); return; } } static size_t bpf_core_hash_fn(const void *key, void *ctx) { return (size_t)key; } static bool bpf_core_equal_fn(const void *k1, const void *k2, void *ctx) { return k1 == k2; } static void *u32_as_hash_key(__u32 x) { return (void *)(uintptr_t)x; } /* * CO-RE relocate single instruction. * * The outline and important points of the algorithm: * 1. For given local type, find corresponding candidate target types. * Candidate type is a type with the same "essential" name, ignoring * everything after last triple underscore (___). E.g., `sample`, * `sample___flavor_one`, `sample___flavor_another_one`, are all candidates * for each other. Names with triple underscore are referred to as * "flavors" and are useful, among other things, to allow to * specify/support incompatible variations of the same kernel struct, which * might differ between different kernel versions and/or build * configurations. * * N.B. Struct "flavors" could be generated by bpftool's BTF-to-C * converter, when deduplicated BTF of a kernel still contains more than * one different types with the same name. In that case, ___2, ___3, etc * are appended starting from second name conflict. But start flavors are * also useful to be defined "locally", in BPF program, to extract same * data from incompatible changes between different kernel * versions/configurations. For instance, to handle field renames between * kernel versions, one can use two flavors of the struct name with the * same common name and use conditional relocations to extract that field, * depending on target kernel version. * 2. For each candidate type, try to match local specification to this * candidate target type. Matching involves finding corresponding * high-level spec accessors, meaning that all named fields should match, * as well as all array accesses should be within the actual bounds. Also, * types should be compatible (see bpf_core_fields_are_compat for details). * 3. It is supported and expected that there might be multiple flavors * matching the spec. As long as all the specs resolve to the same set of * offsets across all candidates, there is no error. If there is any * ambiguity, CO-RE relocation will fail. This is necessary to accomodate * imprefection of BTF deduplication, which can cause slight duplication of * the same BTF type, if some directly or indirectly referenced (by * pointer) type gets resolved to different actual types in different * object files. If such situation occurs, deduplicated BTF will end up * with two (or more) structurally identical types, which differ only in * types they refer to through pointer. This should be OK in most cases and * is not an error. * 4. Candidate types search is performed by linearly scanning through all * types in target BTF. It is anticipated that this is overall more * efficient memory-wise and not significantly worse (if not better) * CPU-wise compared to prebuilding a map from all local type names to * a list of candidate type names. It's also sped up by caching resolved * list of matching candidates per each local "root" type ID, that has at * least one bpf_core_relo associated with it. This list is shared * between multiple relocations for the same type ID and is updated as some * of the candidates are pruned due to structural incompatibility. */ static int bpf_core_apply_relo(struct bpf_program *prog, const struct bpf_core_relo *relo, int relo_idx, const struct btf *local_btf, struct hashmap *cand_cache) { struct bpf_core_spec local_spec, cand_spec, targ_spec = {}; const void *type_key = u32_as_hash_key(relo->type_id); struct bpf_core_relo_res cand_res, targ_res; const struct btf_type *local_type; const char *local_name; struct core_cand_list *cands = NULL; __u32 local_id; const char *spec_str; int i, j, err; local_id = relo->type_id; local_type = btf__type_by_id(local_btf, local_id); if (!local_type) return -EINVAL; local_name = btf__name_by_offset(local_btf, local_type->name_off); if (!local_name) return -EINVAL; spec_str = btf__name_by_offset(local_btf, relo->access_str_off); if (str_is_empty(spec_str)) return -EINVAL; err = bpf_core_parse_spec(local_btf, local_id, spec_str, relo->kind, &local_spec); if (err) { pr_warn("prog '%s': relo #%d: parsing [%d] %s %s + %s failed: %d\n", prog->name, relo_idx, local_id, btf_kind_str(local_type), str_is_empty(local_name) ? "" : local_name, spec_str, err); return -EINVAL; } pr_debug("prog '%s': relo #%d: kind <%s> (%d), spec is ", prog->name, relo_idx, core_relo_kind_str(relo->kind), relo->kind); bpf_core_dump_spec(LIBBPF_DEBUG, &local_spec); libbpf_print(LIBBPF_DEBUG, "\n"); /* TYPE_ID_LOCAL relo is special and doesn't need candidate search */ if (relo->kind == BPF_TYPE_ID_LOCAL) { targ_res.validate = true; targ_res.poison = false; targ_res.orig_val = local_spec.root_type_id; targ_res.new_val = local_spec.root_type_id; goto patch_insn; } /* libbpf doesn't support candidate search for anonymous types */ if (str_is_empty(spec_str)) { pr_warn("prog '%s': relo #%d: <%s> (%d) relocation doesn't support anonymous types\n", prog->name, relo_idx, core_relo_kind_str(relo->kind), relo->kind); return -EOPNOTSUPP; } if (!hashmap__find(cand_cache, type_key, (void **)&cands)) { cands = bpf_core_find_cands(prog->obj, local_btf, local_id); if (IS_ERR(cands)) { pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n", prog->name, relo_idx, local_id, btf_kind_str(local_type), local_name, PTR_ERR(cands)); return PTR_ERR(cands); } err = hashmap__set(cand_cache, type_key, cands, NULL, NULL); if (err) { bpf_core_free_cands(cands); return err; } } for (i = 0, j = 0; i < cands->len; i++) { err = bpf_core_spec_match(&local_spec, cands->cands[i].btf, cands->cands[i].id, &cand_spec); if (err < 0) { pr_warn("prog '%s': relo #%d: error matching candidate #%d ", prog->name, relo_idx, i); bpf_core_dump_spec(LIBBPF_WARN, &cand_spec); libbpf_print(LIBBPF_WARN, ": %d\n", err); return err; } pr_debug("prog '%s': relo #%d: %s candidate #%d ", prog->name, relo_idx, err == 0 ? "non-matching" : "matching", i); bpf_core_dump_spec(LIBBPF_DEBUG, &cand_spec); libbpf_print(LIBBPF_DEBUG, "\n"); if (err == 0) continue; err = bpf_core_calc_relo(prog, relo, relo_idx, &local_spec, &cand_spec, &cand_res); if (err) return err; if (j == 0) { targ_res = cand_res; targ_spec = cand_spec; } else if (cand_spec.bit_offset != targ_spec.bit_offset) { /* if there are many field relo candidates, they * should all resolve to the same bit offset */ pr_warn("prog '%s': relo #%d: field offset ambiguity: %u != %u\n", prog->name, relo_idx, cand_spec.bit_offset, targ_spec.bit_offset); return -EINVAL; } else if (cand_res.poison != targ_res.poison || cand_res.new_val != targ_res.new_val) { /* all candidates should result in the same relocation * decision and value, otherwise it's dangerous to * proceed due to ambiguity */ pr_warn("prog '%s': relo #%d: relocation decision ambiguity: %s %u != %s %u\n", prog->name, relo_idx, cand_res.poison ? "failure" : "success", cand_res.new_val, targ_res.poison ? "failure" : "success", targ_res.new_val); return -EINVAL; } cands->cands[j++] = cands->cands[i]; } /* * For BPF_FIELD_EXISTS relo or when used BPF program has field * existence checks or kernel version/config checks, it's expected * that we might not find any candidates. In this case, if field * wasn't found in any candidate, the list of candidates shouldn't * change at all, we'll just handle relocating appropriately, * depending on relo's kind. */ if (j > 0) cands->len = j; /* * If no candidates were found, it might be both a programmer error, * as well as expected case, depending whether instruction w/ * relocation is guarded in some way that makes it unreachable (dead * code) if relocation can't be resolved. This is handled in * bpf_core_patch_insn() uniformly by replacing that instruction with * BPF helper call insn (using invalid helper ID). If that instruction * is indeed unreachable, then it will be ignored and eliminated by * verifier. If it was an error, then verifier will complain and point * to a specific instruction number in its log. */ if (j == 0) { pr_debug("prog '%s': relo #%d: no matching targets found\n", prog->name, relo_idx); /* calculate single target relo result explicitly */ err = bpf_core_calc_relo(prog, relo, relo_idx, &local_spec, NULL, &targ_res); if (err) return err; } patch_insn: /* bpf_core_patch_insn() should know how to handle missing targ_spec */ err = bpf_core_patch_insn(prog, relo, relo_idx, &targ_res); if (err) { pr_warn("prog '%s': relo #%d: failed to patch insn #%zu: %d\n", prog->name, relo_idx, relo->insn_off / BPF_INSN_SZ, err); return -EINVAL; } return 0; } static int bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path) { const struct btf_ext_info_sec *sec; const struct bpf_core_relo *rec; const struct btf_ext_info *seg; struct hashmap_entry *entry; struct hashmap *cand_cache = NULL; struct bpf_program *prog; const char *sec_name; int i, err = 0, insn_idx, sec_idx; if (obj->btf_ext->core_relo_info.len == 0) return 0; if (targ_btf_path) { obj->btf_vmlinux_override = btf__parse(targ_btf_path, NULL); if (IS_ERR_OR_NULL(obj->btf_vmlinux_override)) { err = PTR_ERR(obj->btf_vmlinux_override); pr_warn("failed to parse target BTF: %d\n", err); return err; } } cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL); if (IS_ERR(cand_cache)) { err = PTR_ERR(cand_cache); goto out; } seg = &obj->btf_ext->core_relo_info; for_each_btf_ext_sec(seg, sec) { sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off); if (str_is_empty(sec_name)) { err = -EINVAL; goto out; } /* bpf_object's ELF is gone by now so it's not easy to find * section index by section name, but we can find *any* * bpf_program within desired section name and use it's * prog->sec_idx to do a proper search by section index and * instruction offset */ prog = NULL; for (i = 0; i < obj->nr_programs; i++) { prog = &obj->programs[i]; if (strcmp(prog->sec_name, sec_name) == 0) break; } if (!prog) { pr_warn("sec '%s': failed to find a BPF program\n", sec_name); return -ENOENT; } sec_idx = prog->sec_idx; pr_debug("sec '%s': found %d CO-RE relocations\n", sec_name, sec->num_info); for_each_btf_ext_rec(seg, sec, i, rec) { insn_idx = rec->insn_off / BPF_INSN_SZ; prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx); if (!prog) { pr_warn("sec '%s': failed to find program at insn #%d for CO-RE offset relocation #%d\n", sec_name, insn_idx, i); err = -EINVAL; goto out; } /* no need to apply CO-RE relocation if the program is * not going to be loaded */ if (!prog->load) continue; err = bpf_core_apply_relo(prog, rec, i, obj->btf, cand_cache); if (err) { pr_warn("prog '%s': relo #%d: failed to relocate: %d\n", prog->name, i, err); goto out; } } } out: /* obj->btf_vmlinux and module BTFs are freed after object load */ btf__free(obj->btf_vmlinux_override); obj->btf_vmlinux_override = NULL; if (!IS_ERR_OR_NULL(cand_cache)) { hashmap__for_each_entry(cand_cache, entry, i) { bpf_core_free_cands(entry->value); } hashmap__free(cand_cache); } return err; } /* Relocate data references within program code: * - map references; * - global variable references; * - extern references. */ static int bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog) { int i; for (i = 0; i < prog->nr_reloc; i++) { struct reloc_desc *relo = &prog->reloc_desc[i]; struct bpf_insn *insn = &prog->insns[relo->insn_idx]; struct extern_desc *ext; switch (relo->type) { case RELO_LD64: insn[0].src_reg = BPF_PSEUDO_MAP_FD; insn[0].imm = obj->maps[relo->map_idx].fd; break; case RELO_DATA: insn[0].src_reg = BPF_PSEUDO_MAP_VALUE; insn[1].imm = insn[0].imm + relo->sym_off; insn[0].imm = obj->maps[relo->map_idx].fd; break; case RELO_EXTERN_VAR: ext = &obj->externs[relo->sym_off]; if (ext->type == EXT_KCFG) { insn[0].src_reg = BPF_PSEUDO_MAP_VALUE; insn[0].imm = obj->maps[obj->kconfig_map_idx].fd; insn[1].imm = ext->kcfg.data_off; } else /* EXT_KSYM */ { if (ext->ksym.type_id) { /* typed ksyms */ insn[0].src_reg = BPF_PSEUDO_BTF_ID; insn[0].imm = ext->ksym.kernel_btf_id; insn[1].imm = ext->ksym.kernel_btf_obj_fd; } else { /* typeless ksyms */ insn[0].imm = (__u32)ext->ksym.addr; insn[1].imm = ext->ksym.addr >> 32; } } break; case RELO_EXTERN_FUNC: ext = &obj->externs[relo->sym_off]; insn[0].src_reg = BPF_PSEUDO_KFUNC_CALL; insn[0].imm = ext->ksym.kernel_btf_id; break; case RELO_SUBPROG_ADDR: insn[0].src_reg = BPF_PSEUDO_FUNC; /* will be handled as a follow up pass */ break; case RELO_CALL: /* will be handled as a follow up pass */ break; default: pr_warn("prog '%s': relo #%d: bad relo type %d\n", prog->name, i, relo->type); return -EINVAL; } } return 0; } static int adjust_prog_btf_ext_info(const struct bpf_object *obj, const struct bpf_program *prog, const struct btf_ext_info *ext_info, void **prog_info, __u32 *prog_rec_cnt, __u32 *prog_rec_sz) { void *copy_start = NULL, *copy_end = NULL; void *rec, *rec_end, *new_prog_info; const struct btf_ext_info_sec *sec; size_t old_sz, new_sz; const char *sec_name; int i, off_adj; for_each_btf_ext_sec(ext_info, sec) { sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off); if (!sec_name) return -EINVAL; if (strcmp(sec_name, prog->sec_name) != 0) continue; for_each_btf_ext_rec(ext_info, sec, i, rec) { __u32 insn_off = *(__u32 *)rec / BPF_INSN_SZ; if (insn_off < prog->sec_insn_off) continue; if (insn_off >= prog->sec_insn_off + prog->sec_insn_cnt) break; if (!copy_start) copy_start = rec; copy_end = rec + ext_info->rec_size; } if (!copy_start) return -ENOENT; /* append func/line info of a given (sub-)program to the main * program func/line info */ old_sz = (size_t)(*prog_rec_cnt) * ext_info->rec_size; new_sz = old_sz + (copy_end - copy_start); new_prog_info = realloc(*prog_info, new_sz); if (!new_prog_info) return -ENOMEM; *prog_info = new_prog_info; *prog_rec_cnt = new_sz / ext_info->rec_size; memcpy(new_prog_info + old_sz, copy_start, copy_end - copy_start); /* Kernel instruction offsets are in units of 8-byte * instructions, while .BTF.ext instruction offsets generated * by Clang are in units of bytes. So convert Clang offsets * into kernel offsets and adjust offset according to program * relocated position. */ off_adj = prog->sub_insn_off - prog->sec_insn_off; rec = new_prog_info + old_sz; rec_end = new_prog_info + new_sz; for (; rec < rec_end; rec += ext_info->rec_size) { __u32 *insn_off = rec; *insn_off = *insn_off / BPF_INSN_SZ + off_adj; } *prog_rec_sz = ext_info->rec_size; return 0; } return -ENOENT; } static int reloc_prog_func_and_line_info(const struct bpf_object *obj, struct bpf_program *main_prog, const struct bpf_program *prog) { int err; /* no .BTF.ext relocation if .BTF.ext is missing or kernel doesn't * supprot func/line info */ if (!obj->btf_ext || !kernel_supports(FEAT_BTF_FUNC)) return 0; /* only attempt func info relocation if main program's func_info * relocation was successful */ if (main_prog != prog && !main_prog->func_info) goto line_info; err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->func_info, &main_prog->func_info, &main_prog->func_info_cnt, &main_prog->func_info_rec_size); if (err) { if (err != -ENOENT) { pr_warn("prog '%s': error relocating .BTF.ext function info: %d\n", prog->name, err); return err; } if (main_prog->func_info) { /* * Some info has already been found but has problem * in the last btf_ext reloc. Must have to error out. */ pr_warn("prog '%s': missing .BTF.ext function info.\n", prog->name); return err; } /* Have problem loading the very first info. Ignore the rest. */ pr_warn("prog '%s': missing .BTF.ext function info for the main program, skipping all of .BTF.ext func info.\n", prog->name); } line_info: /* don't relocate line info if main program's relocation failed */ if (main_prog != prog && !main_prog->line_info) return 0; err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->line_info, &main_prog->line_info, &main_prog->line_info_cnt, &main_prog->line_info_rec_size); if (err) { if (err != -ENOENT) { pr_warn("prog '%s': error relocating .BTF.ext line info: %d\n", prog->name, err); return err; } if (main_prog->line_info) { /* * Some info has already been found but has problem * in the last btf_ext reloc. Must have to error out. */ pr_warn("prog '%s': missing .BTF.ext line info.\n", prog->name); return err; } /* Have problem loading the very first info. Ignore the rest. */ pr_warn("prog '%s': missing .BTF.ext line info for the main program, skipping all of .BTF.ext line info.\n", prog->name); } return 0; } static int cmp_relo_by_insn_idx(const void *key, const void *elem) { size_t insn_idx = *(const size_t *)key; const struct reloc_desc *relo = elem; if (insn_idx == relo->insn_idx) return 0; return insn_idx < relo->insn_idx ? -1 : 1; } static struct reloc_desc *find_prog_insn_relo(const struct bpf_program *prog, size_t insn_idx) { return bsearch(&insn_idx, prog->reloc_desc, prog->nr_reloc, sizeof(*prog->reloc_desc), cmp_relo_by_insn_idx); } static int bpf_object__reloc_code(struct bpf_object *obj, struct bpf_program *main_prog, struct bpf_program *prog) { size_t sub_insn_idx, insn_idx, new_cnt; struct bpf_program *subprog; struct bpf_insn *insns, *insn; struct reloc_desc *relo; int err; err = reloc_prog_func_and_line_info(obj, main_prog, prog); if (err) return err; for (insn_idx = 0; insn_idx < prog->sec_insn_cnt; insn_idx++) { insn = &main_prog->insns[prog->sub_insn_off + insn_idx]; if (!insn_is_subprog_call(insn) && !insn_is_pseudo_func(insn)) continue; relo = find_prog_insn_relo(prog, insn_idx); if (relo && relo->type != RELO_CALL && relo->type != RELO_SUBPROG_ADDR) { pr_warn("prog '%s': unexpected relo for insn #%zu, type %d\n", prog->name, insn_idx, relo->type); return -LIBBPF_ERRNO__RELOC; } if (relo) { /* sub-program instruction index is a combination of * an offset of a symbol pointed to by relocation and * call instruction's imm field; for global functions, * call always has imm = -1, but for static functions * relocation is against STT_SECTION and insn->imm * points to a start of a static function * * for subprog addr relocation, the relo->sym_off + insn->imm is * the byte offset in the corresponding section. */ if (relo->type == RELO_CALL) sub_insn_idx = relo->sym_off / BPF_INSN_SZ + insn->imm + 1; else sub_insn_idx = (relo->sym_off + insn->imm) / BPF_INSN_SZ; } else if (insn_is_pseudo_func(insn)) { /* * RELO_SUBPROG_ADDR relo is always emitted even if both * functions are in the same section, so it shouldn't reach here. */ pr_warn("prog '%s': missing subprog addr relo for insn #%zu\n", prog->name, insn_idx); return -LIBBPF_ERRNO__RELOC; } else { /* if subprogram call is to a static function within * the same ELF section, there won't be any relocation * emitted, but it also means there is no additional * offset necessary, insns->imm is relative to * instruction's original position within the section */ sub_insn_idx = prog->sec_insn_off + insn_idx + insn->imm + 1; } /* we enforce that sub-programs should be in .text section */ subprog = find_prog_by_sec_insn(obj, obj->efile.text_shndx, sub_insn_idx); if (!subprog) { pr_warn("prog '%s': no .text section found yet sub-program call exists\n", prog->name); return -LIBBPF_ERRNO__RELOC; } /* if it's the first call instruction calling into this * subprogram (meaning this subprog hasn't been processed * yet) within the context of current main program: * - append it at the end of main program's instructions blog; * - process is recursively, while current program is put on hold; * - if that subprogram calls some other not yet processes * subprogram, same thing will happen recursively until * there are no more unprocesses subprograms left to append * and relocate. */ if (subprog->sub_insn_off == 0) { subprog->sub_insn_off = main_prog->insns_cnt; new_cnt = main_prog->insns_cnt + subprog->insns_cnt; insns = libbpf_reallocarray(main_prog->insns, new_cnt, sizeof(*insns)); if (!insns) { pr_warn("prog '%s': failed to realloc prog code\n", main_prog->name); return -ENOMEM; } main_prog->insns = insns; main_prog->insns_cnt = new_cnt; memcpy(main_prog->insns + subprog->sub_insn_off, subprog->insns, subprog->insns_cnt * sizeof(*insns)); pr_debug("prog '%s': added %zu insns from sub-prog '%s'\n", main_prog->name, subprog->insns_cnt, subprog->name); err = bpf_object__reloc_code(obj, main_prog, subprog); if (err) return err; } /* main_prog->insns memory could have been re-allocated, so * calculate pointer again */ insn = &main_prog->insns[prog->sub_insn_off + insn_idx]; /* calculate correct instruction position within current main * prog; each main prog can have a different set of * subprograms appended (potentially in different order as * well), so position of any subprog can be different for * different main programs */ insn->imm = subprog->sub_insn_off - (prog->sub_insn_off + insn_idx) - 1; pr_debug("prog '%s': insn #%zu relocated, imm %d points to subprog '%s' (now at %zu offset)\n", prog->name, insn_idx, insn->imm, subprog->name, subprog->sub_insn_off); } return 0; } /* * Relocate sub-program calls. * * Algorithm operates as follows. Each entry-point BPF program (referred to as * main prog) is processed separately. For each subprog (non-entry functions, * that can be called from either entry progs or other subprogs) gets their * sub_insn_off reset to zero. This serves as indicator that this subprogram * hasn't been yet appended and relocated within current main prog. Once its * relocated, sub_insn_off will point at the position within current main prog * where given subprog was appended. This will further be used to relocate all * the call instructions jumping into this subprog. * * We start with main program and process all call instructions. If the call * is into a subprog that hasn't been processed (i.e., subprog->sub_insn_off * is zero), subprog instructions are appended at the end of main program's * instruction array. Then main program is "put on hold" while we recursively * process newly appended subprogram. If that subprogram calls into another * subprogram that hasn't been appended, new subprogram is appended again to * the *main* prog's instructions (subprog's instructions are always left * untouched, as they need to be in unmodified state for subsequent main progs * and subprog instructions are always sent only as part of a main prog) and * the process continues recursively. Once all the subprogs called from a main * prog or any of its subprogs are appended (and relocated), all their * positions within finalized instructions array are known, so it's easy to * rewrite call instructions with correct relative offsets, corresponding to * desired target subprog. * * Its important to realize that some subprogs might not be called from some * main prog and any of its called/used subprogs. Those will keep their * subprog->sub_insn_off as zero at all times and won't be appended to current * main prog and won't be relocated within the context of current main prog. * They might still be used from other main progs later. * * Visually this process can be shown as below. Suppose we have two main * programs mainA and mainB and BPF object contains three subprogs: subA, * subB, and subC. mainA calls only subA, mainB calls only subC, but subA and * subC both call subB: * * +--------+ +-------+ * | v v | * +--+---+ +--+-+-+ +---+--+ * | subA | | subB | | subC | * +--+---+ +------+ +---+--+ * ^ ^ * | | * +---+-------+ +------+----+ * | mainA | | mainB | * +-----------+ +-----------+ * * We'll start relocating mainA, will find subA, append it and start * processing sub A recursively: * * +-----------+------+ * | mainA | subA | * +-----------+------+ * * At this point we notice that subB is used from subA, so we append it and * relocate (there are no further subcalls from subB): * * +-----------+------+------+ * | mainA | subA | subB | * +-----------+------+------+ * * At this point, we relocate subA calls, then go one level up and finish with * relocatin mainA calls. mainA is done. * * For mainB process is similar but results in different order. We start with * mainB and skip subA and subB, as mainB never calls them (at least * directly), but we see subC is needed, so we append and start processing it: * * +-----------+------+ * | mainB | subC | * +-----------+------+ * Now we see subC needs subB, so we go back to it, append and relocate it: * * +-----------+------+------+ * | mainB | subC | subB | * +-----------+------+------+ * * At this point we unwind recursion, relocate calls in subC, then in mainB. */ static int bpf_object__relocate_calls(struct bpf_object *obj, struct bpf_program *prog) { struct bpf_program *subprog; int i, err; /* mark all subprogs as not relocated (yet) within the context of * current main program */ for (i = 0; i < obj->nr_programs; i++) { subprog = &obj->programs[i]; if (!prog_is_subprog(obj, subprog)) continue; subprog->sub_insn_off = 0; } err = bpf_object__reloc_code(obj, prog, prog); if (err) return err; return 0; } static int bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path) { struct bpf_program *prog; size_t i; int err; if (obj->btf_ext) { err = bpf_object__relocate_core(obj, targ_btf_path); if (err) { pr_warn("failed to perform CO-RE relocations: %d\n", err); return err; } } /* relocate data references first for all programs and sub-programs, * as they don't change relative to code locations, so subsequent * subprogram processing won't need to re-calculate any of them */ for (i = 0; i < obj->nr_programs; i++) { prog = &obj->programs[i]; err = bpf_object__relocate_data(obj, prog); if (err) { pr_warn("prog '%s': failed to relocate data references: %d\n", prog->name, err); return err; } } /* now relocate subprogram calls and append used subprograms to main * programs; each copy of subprogram code needs to be relocated * differently for each main program, because its code location might * have changed */ for (i = 0; i < obj->nr_programs; i++) { prog = &obj->programs[i]; /* sub-program's sub-calls are relocated within the context of * its main program only */ if (prog_is_subprog(obj, prog)) continue; err = bpf_object__relocate_calls(obj, prog); if (err) { pr_warn("prog '%s': failed to relocate calls: %d\n", prog->name, err); return err; } } /* free up relocation descriptors */ for (i = 0; i < obj->nr_programs; i++) { prog = &obj->programs[i]; zfree(&prog->reloc_desc); prog->nr_reloc = 0; } return 0; } static int bpf_object__collect_st_ops_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data); static int bpf_object__collect_map_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data) { const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *); int i, j, nrels, new_sz; const struct btf_var_secinfo *vi = NULL; const struct btf_type *sec, *var, *def; struct bpf_map *map = NULL, *targ_map; const struct btf_member *member; const char *name, *mname; Elf_Data *symbols; unsigned int moff; GElf_Sym sym; GElf_Rel rel; void *tmp; if (!obj->efile.btf_maps_sec_btf_id || !obj->btf) return -EINVAL; sec = btf__type_by_id(obj->btf, obj->efile.btf_maps_sec_btf_id); if (!sec) return -EINVAL; symbols = obj->efile.symbols; nrels = shdr->sh_size / shdr->sh_entsize; for (i = 0; i < nrels; i++) { if (!gelf_getrel(data, i, &rel)) { pr_warn(".maps relo #%d: failed to get ELF relo\n", i); return -LIBBPF_ERRNO__FORMAT; } if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) { pr_warn(".maps relo #%d: symbol %zx not found\n", i, (size_t)GELF_R_SYM(rel.r_info)); return -LIBBPF_ERRNO__FORMAT; } name = elf_sym_str(obj, sym.st_name) ?: ""; if (sym.st_shndx != obj->efile.btf_maps_shndx) { pr_warn(".maps relo #%d: '%s' isn't a BTF-defined map\n", i, name); return -LIBBPF_ERRNO__RELOC; } pr_debug(".maps relo #%d: for %zd value %zd rel.r_offset %zu name %d ('%s')\n", i, (ssize_t)(rel.r_info >> 32), (size_t)sym.st_value, (size_t)rel.r_offset, sym.st_name, name); for (j = 0; j < obj->nr_maps; j++) { map = &obj->maps[j]; if (map->sec_idx != obj->efile.btf_maps_shndx) continue; vi = btf_var_secinfos(sec) + map->btf_var_idx; if (vi->offset <= rel.r_offset && rel.r_offset + bpf_ptr_sz <= vi->offset + vi->size) break; } if (j == obj->nr_maps) { pr_warn(".maps relo #%d: cannot find map '%s' at rel.r_offset %zu\n", i, name, (size_t)rel.r_offset); return -EINVAL; } if (!bpf_map_type__is_map_in_map(map->def.type)) return -EINVAL; if (map->def.type == BPF_MAP_TYPE_HASH_OF_MAPS && map->def.key_size != sizeof(int)) { pr_warn(".maps relo #%d: hash-of-maps '%s' should have key size %zu.\n", i, map->name, sizeof(int)); return -EINVAL; } targ_map = bpf_object__find_map_by_name(obj, name); if (!targ_map) return -ESRCH; var = btf__type_by_id(obj->btf, vi->type); def = skip_mods_and_typedefs(obj->btf, var->type, NULL); if (btf_vlen(def) == 0) return -EINVAL; member = btf_members(def) + btf_vlen(def) - 1; mname = btf__name_by_offset(obj->btf, member->name_off); if (strcmp(mname, "values")) return -EINVAL; moff = btf_member_bit_offset(def, btf_vlen(def) - 1) / 8; if (rel.r_offset - vi->offset < moff) return -EINVAL; moff = rel.r_offset - vi->offset - moff; /* here we use BPF pointer size, which is always 64 bit, as we * are parsing ELF that was built for BPF target */ if (moff % bpf_ptr_sz) return -EINVAL; moff /= bpf_ptr_sz; if (moff >= map->init_slots_sz) { new_sz = moff + 1; tmp = libbpf_reallocarray(map->init_slots, new_sz, host_ptr_sz); if (!tmp) return -ENOMEM; map->init_slots = tmp; memset(map->init_slots + map->init_slots_sz, 0, (new_sz - map->init_slots_sz) * host_ptr_sz); map->init_slots_sz = new_sz; } map->init_slots[moff] = targ_map; pr_debug(".maps relo #%d: map '%s' slot [%d] points to map '%s'\n", i, map->name, moff, name); } return 0; } static int cmp_relocs(const void *_a, const void *_b) { const struct reloc_desc *a = _a; const struct reloc_desc *b = _b; if (a->insn_idx != b->insn_idx) return a->insn_idx < b->insn_idx ? -1 : 1; /* no two relocations should have the same insn_idx, but ... */ if (a->type != b->type) return a->type < b->type ? -1 : 1; return 0; } static int bpf_object__collect_relos(struct bpf_object *obj) { int i, err; for (i = 0; i < obj->efile.nr_reloc_sects; i++) { GElf_Shdr *shdr = &obj->efile.reloc_sects[i].shdr; Elf_Data *data = obj->efile.reloc_sects[i].data; int idx = shdr->sh_info; if (shdr->sh_type != SHT_REL) { pr_warn("internal error at %d\n", __LINE__); return -LIBBPF_ERRNO__INTERNAL; } if (idx == obj->efile.st_ops_shndx) err = bpf_object__collect_st_ops_relos(obj, shdr, data); else if (idx == obj->efile.btf_maps_shndx) err = bpf_object__collect_map_relos(obj, shdr, data); else err = bpf_object__collect_prog_relos(obj, shdr, data); if (err) return err; } for (i = 0; i < obj->nr_programs; i++) { struct bpf_program *p = &obj->programs[i]; if (!p->nr_reloc) continue; qsort(p->reloc_desc, p->nr_reloc, sizeof(*p->reloc_desc), cmp_relocs); } return 0; } static bool insn_is_helper_call(struct bpf_insn *insn, enum bpf_func_id *func_id) { if (BPF_CLASS(insn->code) == BPF_JMP && BPF_OP(insn->code) == BPF_CALL && BPF_SRC(insn->code) == BPF_K && insn->src_reg == 0 && insn->dst_reg == 0) { *func_id = insn->imm; return true; } return false; } static int bpf_object__sanitize_prog(struct bpf_object *obj, struct bpf_program *prog) { struct bpf_insn *insn = prog->insns; enum bpf_func_id func_id; int i; for (i = 0; i < prog->insns_cnt; i++, insn++) { if (!insn_is_helper_call(insn, &func_id)) continue; /* on kernels that don't yet support * bpf_probe_read_{kernel,user}[_str] helpers, fall back * to bpf_probe_read() which works well for old kernels */ switch (func_id) { case BPF_FUNC_probe_read_kernel: case BPF_FUNC_probe_read_user: if (!kernel_supports(FEAT_PROBE_READ_KERN)) insn->imm = BPF_FUNC_probe_read; break; case BPF_FUNC_probe_read_kernel_str: case BPF_FUNC_probe_read_user_str: if (!kernel_supports(FEAT_PROBE_READ_KERN)) insn->imm = BPF_FUNC_probe_read_str; break; default: break; } } return 0; } static int load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, char *license, __u32 kern_version, int *pfd) { struct bpf_prog_load_params load_attr = {}; char *cp, errmsg[STRERR_BUFSIZE]; size_t log_buf_size = 0; char *log_buf = NULL; int btf_fd, ret; if (prog->type == BPF_PROG_TYPE_UNSPEC) { /* * The program type must be set. Most likely we couldn't find a proper * section definition at load time, and thus we didn't infer the type. */ pr_warn("prog '%s': missing BPF prog type, check ELF section name '%s'\n", prog->name, prog->sec_name); return -EINVAL; } if (!insns || !insns_cnt) return -EINVAL; load_attr.prog_type = prog->type; /* old kernels might not support specifying expected_attach_type */ if (!kernel_supports(FEAT_EXP_ATTACH_TYPE) && prog->sec_def && prog->sec_def->is_exp_attach_type_optional) load_attr.expected_attach_type = 0; else load_attr.expected_attach_type = prog->expected_attach_type; if (kernel_supports(FEAT_PROG_NAME)) load_attr.name = prog->name; load_attr.insns = insns; load_attr.insn_cnt = insns_cnt; load_attr.license = license; load_attr.attach_btf_id = prog->attach_btf_id; if (prog->attach_prog_fd) load_attr.attach_prog_fd = prog->attach_prog_fd; else load_attr.attach_btf_obj_fd = prog->attach_btf_obj_fd; load_attr.attach_btf_id = prog->attach_btf_id; load_attr.kern_version = kern_version; load_attr.prog_ifindex = prog->prog_ifindex; /* specify func_info/line_info only if kernel supports them */ btf_fd = bpf_object__btf_fd(prog->obj); if (btf_fd >= 0 && kernel_supports(FEAT_BTF_FUNC)) { load_attr.prog_btf_fd = btf_fd; load_attr.func_info = prog->func_info; load_attr.func_info_rec_size = prog->func_info_rec_size; load_attr.func_info_cnt = prog->func_info_cnt; load_attr.line_info = prog->line_info; load_attr.line_info_rec_size = prog->line_info_rec_size; load_attr.line_info_cnt = prog->line_info_cnt; } load_attr.log_level = prog->log_level; load_attr.prog_flags = prog->prog_flags; retry_load: if (log_buf_size) { log_buf = malloc(log_buf_size); if (!log_buf) return -ENOMEM; *log_buf = 0; } load_attr.log_buf = log_buf; load_attr.log_buf_sz = log_buf_size; ret = libbpf__bpf_prog_load(&load_attr); if (ret >= 0) { if (log_buf && load_attr.log_level) pr_debug("verifier log:\n%s", log_buf); if (prog->obj->rodata_map_idx >= 0 && kernel_supports(FEAT_PROG_BIND_MAP)) { struct bpf_map *rodata_map = &prog->obj->maps[prog->obj->rodata_map_idx]; if (bpf_prog_bind_map(ret, bpf_map__fd(rodata_map), NULL)) { cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); pr_warn("prog '%s': failed to bind .rodata map: %s\n", prog->name, cp); /* Don't fail hard if can't bind rodata. */ } } *pfd = ret; ret = 0; goto out; } if (!log_buf || errno == ENOSPC) { log_buf_size = max((size_t)BPF_LOG_BUF_SIZE, log_buf_size << 1); free(log_buf); goto retry_load; } ret = errno ? -errno : -LIBBPF_ERRNO__LOAD; cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); pr_warn("load bpf program failed: %s\n", cp); pr_perm_msg(ret); if (log_buf && log_buf[0] != '\0') { ret = -LIBBPF_ERRNO__VERIFY; pr_warn("-- BEGIN DUMP LOG ---\n"); pr_warn("\n%s\n", log_buf); pr_warn("-- END LOG --\n"); } else if (load_attr.insn_cnt >= BPF_MAXINSNS) { pr_warn("Program too large (%zu insns), at most %d insns\n", load_attr.insn_cnt, BPF_MAXINSNS); ret = -LIBBPF_ERRNO__PROG2BIG; } else if (load_attr.prog_type != BPF_PROG_TYPE_KPROBE) { /* Wrong program type? */ int fd; load_attr.prog_type = BPF_PROG_TYPE_KPROBE; load_attr.expected_attach_type = 0; load_attr.log_buf = NULL; load_attr.log_buf_sz = 0; fd = libbpf__bpf_prog_load(&load_attr); if (fd >= 0) { close(fd); ret = -LIBBPF_ERRNO__PROGTYPE; goto out; } } out: free(log_buf); return ret; } static int libbpf_find_attach_btf_id(struct bpf_program *prog, int *btf_obj_fd, int *btf_type_id); int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver) { int err = 0, fd, i; if (prog->obj->loaded) { pr_warn("prog '%s': can't load after object was loaded\n", prog->name); return -EINVAL; } if ((prog->type == BPF_PROG_TYPE_TRACING || prog->type == BPF_PROG_TYPE_LSM || prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) { int btf_obj_fd = 0, btf_type_id = 0; err = libbpf_find_attach_btf_id(prog, &btf_obj_fd, &btf_type_id); if (err) return err; prog->attach_btf_obj_fd = btf_obj_fd; prog->attach_btf_id = btf_type_id; } if (prog->instances.nr < 0 || !prog->instances.fds) { if (prog->preprocessor) { pr_warn("Internal error: can't load program '%s'\n", prog->name); return -LIBBPF_ERRNO__INTERNAL; } prog->instances.fds = malloc(sizeof(int)); if (!prog->instances.fds) { pr_warn("Not enough memory for BPF fds\n"); return -ENOMEM; } prog->instances.nr = 1; prog->instances.fds[0] = -1; } if (!prog->preprocessor) { if (prog->instances.nr != 1) { pr_warn("prog '%s': inconsistent nr(%d) != 1\n", prog->name, prog->instances.nr); } err = load_program(prog, prog->insns, prog->insns_cnt, license, kern_ver, &fd); if (!err) prog->instances.fds[0] = fd; goto out; } for (i = 0; i < prog->instances.nr; i++) { struct bpf_prog_prep_result result; bpf_program_prep_t preprocessor = prog->preprocessor; memset(&result, 0, sizeof(result)); err = preprocessor(prog, i, prog->insns, prog->insns_cnt, &result); if (err) { pr_warn("Preprocessing the %dth instance of program '%s' failed\n", i, prog->name); goto out; } if (!result.new_insn_ptr || !result.new_insn_cnt) { pr_debug("Skip loading the %dth instance of program '%s'\n", i, prog->name); prog->instances.fds[i] = -1; if (result.pfd) *result.pfd = -1; continue; } err = load_program(prog, result.new_insn_ptr, result.new_insn_cnt, license, kern_ver, &fd); if (err) { pr_warn("Loading the %dth instance of program '%s' failed\n", i, prog->name); goto out; } if (result.pfd) *result.pfd = fd; prog->instances.fds[i] = fd; } out: if (err) pr_warn("failed to load program '%s'\n", prog->name); zfree(&prog->insns); prog->insns_cnt = 0; return err; } static int bpf_object__load_progs(struct bpf_object *obj, int log_level) { struct bpf_program *prog; size_t i; int err; for (i = 0; i < obj->nr_programs; i++) { prog = &obj->programs[i]; err = bpf_object__sanitize_prog(obj, prog); if (err) return err; } for (i = 0; i < obj->nr_programs; i++) { prog = &obj->programs[i]; if (prog_is_subprog(obj, prog)) continue; if (!prog->load) { pr_debug("prog '%s': skipped loading\n", prog->name); continue; } prog->log_level |= log_level; err = bpf_program__load(prog, obj->license, obj->kern_version); if (err) return err; } return 0; } static const struct bpf_sec_def *find_sec_def(const char *sec_name); static struct bpf_object * __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, const struct bpf_object_open_opts *opts) { const char *obj_name, *kconfig; struct bpf_program *prog; struct bpf_object *obj; char tmp_name[64]; int err; if (elf_version(EV_CURRENT) == EV_NONE) { pr_warn("failed to init libelf for %s\n", path ? : "(mem buf)"); return ERR_PTR(-LIBBPF_ERRNO__LIBELF); } if (!OPTS_VALID(opts, bpf_object_open_opts)) return ERR_PTR(-EINVAL); obj_name = OPTS_GET(opts, object_name, NULL); if (obj_buf) { if (!obj_name) { snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx", (unsigned long)obj_buf, (unsigned long)obj_buf_sz); obj_name = tmp_name; } path = obj_name; pr_debug("loading object '%s' from buffer\n", obj_name); } obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name); if (IS_ERR(obj)) return obj; kconfig = OPTS_GET(opts, kconfig, NULL); if (kconfig) { obj->kconfig = strdup(kconfig); if (!obj->kconfig) return ERR_PTR(-ENOMEM); } err = bpf_object__elf_init(obj); err = err ? : bpf_object__check_endianness(obj); err = err ? : bpf_object__elf_collect(obj); err = err ? : bpf_object__collect_externs(obj); err = err ? : bpf_object__finalize_btf(obj); err = err ? : bpf_object__init_maps(obj, opts); err = err ? : bpf_object__collect_relos(obj); if (err) goto out; bpf_object__elf_finish(obj); bpf_object__for_each_program(prog, obj) { prog->sec_def = find_sec_def(prog->sec_name); if (!prog->sec_def) { /* couldn't guess, but user might manually specify */ pr_debug("prog '%s': unrecognized ELF section name '%s'\n", prog->name, prog->sec_name); continue; } if (prog->sec_def->is_sleepable) prog->prog_flags |= BPF_F_SLEEPABLE; bpf_program__set_type(prog, prog->sec_def->prog_type); bpf_program__set_expected_attach_type(prog, prog->sec_def->expected_attach_type); if (prog->sec_def->prog_type == BPF_PROG_TYPE_TRACING || prog->sec_def->prog_type == BPF_PROG_TYPE_EXT) prog->attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0); } return obj; out: bpf_object__close(obj); return ERR_PTR(err); } static struct bpf_object * __bpf_object__open_xattr(struct bpf_object_open_attr *attr, int flags) { DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, .relaxed_maps = flags & MAPS_RELAX_COMPAT, ); /* param validation */ if (!attr->file) return NULL; pr_debug("loading %s\n", attr->file); return __bpf_object__open(attr->file, NULL, 0, &opts); } struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr) { return __bpf_object__open_xattr(attr, 0); } struct bpf_object *bpf_object__open(const char *path) { struct bpf_object_open_attr attr = { .file = path, .prog_type = BPF_PROG_TYPE_UNSPEC, }; return bpf_object__open_xattr(&attr); } struct bpf_object * bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts) { if (!path) return ERR_PTR(-EINVAL); pr_debug("loading %s\n", path); return __bpf_object__open(path, NULL, 0, opts); } struct bpf_object * bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz, const struct bpf_object_open_opts *opts) { if (!obj_buf || obj_buf_sz == 0) return ERR_PTR(-EINVAL); return __bpf_object__open(NULL, obj_buf, obj_buf_sz, opts); } struct bpf_object * bpf_object__open_buffer(const void *obj_buf, size_t obj_buf_sz, const char *name) { DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, .object_name = name, /* wrong default, but backwards-compatible */ .relaxed_maps = true, ); /* returning NULL is wrong, but backwards-compatible */ if (!obj_buf || obj_buf_sz == 0) return NULL; return bpf_object__open_mem(obj_buf, obj_buf_sz, &opts); } int bpf_object__unload(struct bpf_object *obj) { size_t i; if (!obj) return -EINVAL; for (i = 0; i < obj->nr_maps; i++) { zclose(obj->maps[i].fd); if (obj->maps[i].st_ops) zfree(&obj->maps[i].st_ops->kern_vdata); } for (i = 0; i < obj->nr_programs; i++) bpf_program__unload(&obj->programs[i]); return 0; } static int bpf_object__sanitize_maps(struct bpf_object *obj) { struct bpf_map *m; bpf_object__for_each_map(m, obj) { if (!bpf_map__is_internal(m)) continue; if (!kernel_supports(FEAT_GLOBAL_DATA)) { pr_warn("kernel doesn't support global data\n"); return -ENOTSUP; } if (!kernel_supports(FEAT_ARRAY_MMAP)) m->def.map_flags ^= BPF_F_MMAPABLE; } return 0; } static int bpf_object__read_kallsyms_file(struct bpf_object *obj) { char sym_type, sym_name[500]; unsigned long long sym_addr; const struct btf_type *t; struct extern_desc *ext; int ret, err = 0; FILE *f; f = fopen("/proc/kallsyms", "r"); if (!f) { err = -errno; pr_warn("failed to open /proc/kallsyms: %d\n", err); return err; } while (true) { ret = fscanf(f, "%llx %c %499s%*[^\n]\n", &sym_addr, &sym_type, sym_name); if (ret == EOF && feof(f)) break; if (ret != 3) { pr_warn("failed to read kallsyms entry: %d\n", ret); err = -EINVAL; goto out; } ext = find_extern_by_name(obj, sym_name); if (!ext || ext->type != EXT_KSYM) continue; t = btf__type_by_id(obj->btf, ext->btf_id); if (!btf_is_var(t)) continue; if (ext->is_set && ext->ksym.addr != sym_addr) { pr_warn("extern (ksym) '%s' resolution is ambiguous: 0x%llx or 0x%llx\n", sym_name, ext->ksym.addr, sym_addr); err = -EINVAL; goto out; } if (!ext->is_set) { ext->is_set = true; ext->ksym.addr = sym_addr; pr_debug("extern (ksym) %s=0x%llx\n", sym_name, sym_addr); } } out: fclose(f); return err; } static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name, __u16 kind, struct btf **res_btf, int *res_btf_fd) { int i, id, btf_fd, err; struct btf *btf; btf = obj->btf_vmlinux; btf_fd = 0; id = btf__find_by_name_kind(btf, ksym_name, kind); if (id == -ENOENT) { err = load_module_btfs(obj); if (err) return err; for (i = 0; i < obj->btf_module_cnt; i++) { btf = obj->btf_modules[i].btf; /* we assume module BTF FD is always >0 */ btf_fd = obj->btf_modules[i].fd; id = btf__find_by_name_kind(btf, ksym_name, kind); if (id != -ENOENT) break; } } if (id <= 0) { pr_warn("extern (%s ksym) '%s': failed to find BTF ID in kernel BTF(s).\n", __btf_kind_str(kind), ksym_name); return -ESRCH; } *res_btf = btf; *res_btf_fd = btf_fd; return id; } static int bpf_object__resolve_ksym_var_btf_id(struct bpf_object *obj, struct extern_desc *ext) { const struct btf_type *targ_var, *targ_type; __u32 targ_type_id, local_type_id; const char *targ_var_name; int id, btf_fd = 0, err; struct btf *btf = NULL; id = find_ksym_btf_id(obj, ext->name, BTF_KIND_VAR, &btf, &btf_fd); if (id < 0) return id; /* find local type_id */ local_type_id = ext->ksym.type_id; /* find target type_id */ targ_var = btf__type_by_id(btf, id); targ_var_name = btf__name_by_offset(btf, targ_var->name_off); targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id); err = bpf_core_types_are_compat(obj->btf, local_type_id, btf, targ_type_id); if (err <= 0) { const struct btf_type *local_type; const char *targ_name, *local_name; local_type = btf__type_by_id(obj->btf, local_type_id); local_name = btf__name_by_offset(obj->btf, local_type->name_off); targ_name = btf__name_by_offset(btf, targ_type->name_off); pr_warn("extern (var ksym) '%s': incompatible types, expected [%d] %s %s, but kernel has [%d] %s %s\n", ext->name, local_type_id, btf_kind_str(local_type), local_name, targ_type_id, btf_kind_str(targ_type), targ_name); return -EINVAL; } ext->is_set = true; ext->ksym.kernel_btf_obj_fd = btf_fd; ext->ksym.kernel_btf_id = id; pr_debug("extern (var ksym) '%s': resolved to [%d] %s %s\n", ext->name, id, btf_kind_str(targ_var), targ_var_name); return 0; } static int bpf_object__resolve_ksym_func_btf_id(struct bpf_object *obj, struct extern_desc *ext) { int local_func_proto_id, kfunc_proto_id, kfunc_id; const struct btf_type *kern_func; struct btf *kern_btf = NULL; int ret, kern_btf_fd = 0; local_func_proto_id = ext->ksym.type_id; kfunc_id = find_ksym_btf_id(obj, ext->name, BTF_KIND_FUNC, &kern_btf, &kern_btf_fd); if (kfunc_id < 0) { pr_warn("extern (func ksym) '%s': not found in kernel BTF\n", ext->name); return kfunc_id; } if (kern_btf != obj->btf_vmlinux) { pr_warn("extern (func ksym) '%s': function in kernel module is not supported\n", ext->name); return -ENOTSUP; } kern_func = btf__type_by_id(kern_btf, kfunc_id); kfunc_proto_id = kern_func->type; ret = bpf_core_types_are_compat(obj->btf, local_func_proto_id, kern_btf, kfunc_proto_id); if (ret <= 0) { pr_warn("extern (func ksym) '%s': func_proto [%d] incompatible with kernel [%d]\n", ext->name, local_func_proto_id, kfunc_proto_id); return -EINVAL; } ext->is_set = true; ext->ksym.kernel_btf_obj_fd = kern_btf_fd; ext->ksym.kernel_btf_id = kfunc_id; pr_debug("extern (func ksym) '%s': resolved to kernel [%d]\n", ext->name, kfunc_id); return 0; } static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) { const struct btf_type *t; struct extern_desc *ext; int i, err; for (i = 0; i < obj->nr_extern; i++) { ext = &obj->externs[i]; if (ext->type != EXT_KSYM || !ext->ksym.type_id) continue; t = btf__type_by_id(obj->btf, ext->btf_id); if (btf_is_var(t)) err = bpf_object__resolve_ksym_var_btf_id(obj, ext); else err = bpf_object__resolve_ksym_func_btf_id(obj, ext); if (err) return err; } return 0; } static int bpf_object__resolve_externs(struct bpf_object *obj, const char *extra_kconfig) { bool need_config = false, need_kallsyms = false; bool need_vmlinux_btf = false; struct extern_desc *ext; void *kcfg_data = NULL; int err, i; if (obj->nr_extern == 0) return 0; if (obj->kconfig_map_idx >= 0) kcfg_data = obj->maps[obj->kconfig_map_idx].mmaped; for (i = 0; i < obj->nr_extern; i++) { ext = &obj->externs[i]; if (ext->type == EXT_KCFG && strcmp(ext->name, "LINUX_KERNEL_VERSION") == 0) { void *ext_val = kcfg_data + ext->kcfg.data_off; __u32 kver = get_kernel_version(); if (!kver) { pr_warn("failed to get kernel version\n"); return -EINVAL; } err = set_kcfg_value_num(ext, ext_val, kver); if (err) return err; pr_debug("extern (kcfg) %s=0x%x\n", ext->name, kver); } else if (ext->type == EXT_KCFG && strncmp(ext->name, "CONFIG_", 7) == 0) { need_config = true; } else if (ext->type == EXT_KSYM) { if (ext->ksym.type_id) need_vmlinux_btf = true; else need_kallsyms = true; } else { pr_warn("unrecognized extern '%s'\n", ext->name); return -EINVAL; } } if (need_config && extra_kconfig) { err = bpf_object__read_kconfig_mem(obj, extra_kconfig, kcfg_data); if (err) return -EINVAL; need_config = false; for (i = 0; i < obj->nr_extern; i++) { ext = &obj->externs[i]; if (ext->type == EXT_KCFG && !ext->is_set) { need_config = true; break; } } } if (need_config) { err = bpf_object__read_kconfig_file(obj, kcfg_data); if (err) return -EINVAL; } if (need_kallsyms) { err = bpf_object__read_kallsyms_file(obj); if (err) return -EINVAL; } if (need_vmlinux_btf) { err = bpf_object__resolve_ksyms_btf_id(obj); if (err) return -EINVAL; } for (i = 0; i < obj->nr_extern; i++) { ext = &obj->externs[i]; if (!ext->is_set && !ext->is_weak) { pr_warn("extern %s (strong) not resolved\n", ext->name); return -ESRCH; } else if (!ext->is_set) { pr_debug("extern %s (weak) not resolved, defaulting to zero\n", ext->name); } } return 0; } int bpf_object__load_xattr(struct bpf_object_load_attr *attr) { struct bpf_object *obj; int err, i; if (!attr) return -EINVAL; obj = attr->obj; if (!obj) return -EINVAL; if (obj->loaded) { pr_warn("object '%s': load can't be attempted twice\n", obj->name); return -EINVAL; } err = bpf_object__probe_loading(obj); err = err ? : bpf_object__load_vmlinux_btf(obj, false); err = err ? : bpf_object__resolve_externs(obj, obj->kconfig); err = err ? : bpf_object__sanitize_and_load_btf(obj); err = err ? : bpf_object__sanitize_maps(obj); err = err ? : bpf_object__init_kern_struct_ops_maps(obj); err = err ? : bpf_object__create_maps(obj); err = err ? : bpf_object__relocate(obj, attr->target_btf_path); err = err ? : bpf_object__load_progs(obj, attr->log_level); /* clean up module BTFs */ for (i = 0; i < obj->btf_module_cnt; i++) { close(obj->btf_modules[i].fd); btf__free(obj->btf_modules[i].btf); free(obj->btf_modules[i].name); } free(obj->btf_modules); /* clean up vmlinux BTF */ btf__free(obj->btf_vmlinux); obj->btf_vmlinux = NULL; obj->loaded = true; /* doesn't matter if successfully or not */ if (err) goto out; return 0; out: /* unpin any maps that were auto-pinned during load */ for (i = 0; i < obj->nr_maps; i++) if (obj->maps[i].pinned && !obj->maps[i].reused) bpf_map__unpin(&obj->maps[i], NULL); bpf_object__unload(obj); pr_warn("failed to load object '%s'\n", obj->path); return err; } int bpf_object__load(struct bpf_object *obj) { struct bpf_object_load_attr attr = { .obj = obj, }; return bpf_object__load_xattr(&attr); } static int make_parent_dir(const char *path) { char *cp, errmsg[STRERR_BUFSIZE]; char *dname, *dir; int err = 0; dname = strdup(path); if (dname == NULL) return -ENOMEM; dir = dirname(dname); if (mkdir(dir, 0700) && errno != EEXIST) err = -errno; free(dname); if (err) { cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg)); pr_warn("failed to mkdir %s: %s\n", path, cp); } return err; } static int check_path(const char *path) { char *cp, errmsg[STRERR_BUFSIZE]; struct statfs st_fs; char *dname, *dir; int err = 0; if (path == NULL) return -EINVAL; dname = strdup(path); if (dname == NULL) return -ENOMEM; dir = dirname(dname); if (statfs(dir, &st_fs)) { cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); pr_warn("failed to statfs %s: %s\n", dir, cp); err = -errno; } free(dname); if (!err && st_fs.f_type != BPF_FS_MAGIC) { pr_warn("specified path %s is not on BPF FS\n", path); err = -EINVAL; } return err; } int bpf_program__pin_instance(struct bpf_program *prog, const char *path, int instance) { char *cp, errmsg[STRERR_BUFSIZE]; int err; err = make_parent_dir(path); if (err) return err; err = check_path(path); if (err) return err; if (prog == NULL) { pr_warn("invalid program pointer\n"); return -EINVAL; } if (instance < 0 || instance >= prog->instances.nr) { pr_warn("invalid prog instance %d of prog %s (max %d)\n", instance, prog->name, prog->instances.nr); return -EINVAL; } if (bpf_obj_pin(prog->instances.fds[instance], path)) { err = -errno; cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg)); pr_warn("failed to pin program: %s\n", cp); return err; } pr_debug("pinned program '%s'\n", path); return 0; } int bpf_program__unpin_instance(struct bpf_program *prog, const char *path, int instance) { int err; err = check_path(path); if (err) return err; if (prog == NULL) { pr_warn("invalid program pointer\n"); return -EINVAL; } if (instance < 0 || instance >= prog->instances.nr) { pr_warn("invalid prog instance %d of prog %s (max %d)\n", instance, prog->name, prog->instances.nr); return -EINVAL; } err = unlink(path); if (err != 0) return -errno; pr_debug("unpinned program '%s'\n", path); return 0; } int bpf_program__pin(struct bpf_program *prog, const char *path) { int i, err; err = make_parent_dir(path); if (err) return err; err = check_path(path); if (err) return err; if (prog == NULL) { pr_warn("invalid program pointer\n"); return -EINVAL; } if (prog->instances.nr <= 0) { pr_warn("no instances of prog %s to pin\n", prog->name); return -EINVAL; } if (prog->instances.nr == 1) { /* don't create subdirs when pinning single instance */ return bpf_program__pin_instance(prog, path, 0); } for (i = 0; i < prog->instances.nr; i++) { char buf[PATH_MAX]; int len; len = snprintf(buf, PATH_MAX, "%s/%d", path, i); if (len < 0) { err = -EINVAL; goto err_unpin; } else if (len >= PATH_MAX) { err = -ENAMETOOLONG; goto err_unpin; } err = bpf_program__pin_instance(prog, buf, i); if (err) goto err_unpin; } return 0; err_unpin: for (i = i - 1; i >= 0; i--) { char buf[PATH_MAX]; int len; len = snprintf(buf, PATH_MAX, "%s/%d", path, i); if (len < 0) continue; else if (len >= PATH_MAX) continue; bpf_program__unpin_instance(prog, buf, i); } rmdir(path); return err; } int bpf_program__unpin(struct bpf_program *prog, const char *path) { int i, err; err = check_path(path); if (err) return err; if (prog == NULL) { pr_warn("invalid program pointer\n"); return -EINVAL; } if (prog->instances.nr <= 0) { pr_warn("no instances of prog %s to pin\n", prog->name); return -EINVAL; } if (prog->instances.nr == 1) { /* don't create subdirs when pinning single instance */ return bpf_program__unpin_instance(prog, path, 0); } for (i = 0; i < prog->instances.nr; i++) { char buf[PATH_MAX]; int len; len = snprintf(buf, PATH_MAX, "%s/%d", path, i); if (len < 0) return -EINVAL; else if (len >= PATH_MAX) return -ENAMETOOLONG; err = bpf_program__unpin_instance(prog, buf, i); if (err) return err; } err = rmdir(path); if (err) return -errno; return 0; } int bpf_map__pin(struct bpf_map *map, const char *path) { char *cp, errmsg[STRERR_BUFSIZE]; int err; if (map == NULL) { pr_warn("invalid map pointer\n"); return -EINVAL; } if (map->pin_path) { if (path && strcmp(path, map->pin_path)) { pr_warn("map '%s' already has pin path '%s' different from '%s'\n", bpf_map__name(map), map->pin_path, path); return -EINVAL; } else if (map->pinned) { pr_debug("map '%s' already pinned at '%s'; not re-pinning\n", bpf_map__name(map), map->pin_path); return 0; } } else { if (!path) { pr_warn("missing a path to pin map '%s' at\n", bpf_map__name(map)); return -EINVAL; } else if (map->pinned) { pr_warn("map '%s' already pinned\n", bpf_map__name(map)); return -EEXIST; } map->pin_path = strdup(path); if (!map->pin_path) { err = -errno; goto out_err; } } err = make_parent_dir(map->pin_path); if (err) return err; err = check_path(map->pin_path); if (err) return err; if (bpf_obj_pin(map->fd, map->pin_path)) { err = -errno; goto out_err; } map->pinned = true; pr_debug("pinned map '%s'\n", map->pin_path); return 0; out_err: cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg)); pr_warn("failed to pin map: %s\n", cp); return err; } int bpf_map__unpin(struct bpf_map *map, const char *path) { int err; if (map == NULL) { pr_warn("invalid map pointer\n"); return -EINVAL; } if (map->pin_path) { if (path && strcmp(path, map->pin_path)) { pr_warn("map '%s' already has pin path '%s' different from '%s'\n", bpf_map__name(map), map->pin_path, path); return -EINVAL; } path = map->pin_path; } else if (!path) { pr_warn("no path to unpin map '%s' from\n", bpf_map__name(map)); return -EINVAL; } err = check_path(path); if (err) return err; err = unlink(path); if (err != 0) return -errno; map->pinned = false; pr_debug("unpinned map '%s' from '%s'\n", bpf_map__name(map), path); return 0; } int bpf_map__set_pin_path(struct bpf_map *map, const char *path) { char *new = NULL; if (path) { new = strdup(path); if (!new) return -errno; } free(map->pin_path); map->pin_path = new; return 0; } const char *bpf_map__get_pin_path(const struct bpf_map *map) { return map->pin_path; } bool bpf_map__is_pinned(const struct bpf_map *map) { return map->pinned; } static void sanitize_pin_path(char *s) { /* bpffs disallows periods in path names */ while (*s) { if (*s == '.') *s = '_'; s++; } } int bpf_object__pin_maps(struct bpf_object *obj, const char *path) { struct bpf_map *map; int err; if (!obj) return -ENOENT; if (!obj->loaded) { pr_warn("object not yet loaded; load it first\n"); return -ENOENT; } bpf_object__for_each_map(map, obj) { char *pin_path = NULL; char buf[PATH_MAX]; if (path) { int len; len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map)); if (len < 0) { err = -EINVAL; goto err_unpin_maps; } else if (len >= PATH_MAX) { err = -ENAMETOOLONG; goto err_unpin_maps; } sanitize_pin_path(buf); pin_path = buf; } else if (!map->pin_path) { continue; } err = bpf_map__pin(map, pin_path); if (err) goto err_unpin_maps; } return 0; err_unpin_maps: while ((map = bpf_map__prev(map, obj))) { if (!map->pin_path) continue; bpf_map__unpin(map, NULL); } return err; } int bpf_object__unpin_maps(struct bpf_object *obj, const char *path) { struct bpf_map *map; int err; if (!obj) return -ENOENT; bpf_object__for_each_map(map, obj) { char *pin_path = NULL; char buf[PATH_MAX]; if (path) { int len; len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map)); if (len < 0) return -EINVAL; else if (len >= PATH_MAX) return -ENAMETOOLONG; sanitize_pin_path(buf); pin_path = buf; } else if (!map->pin_path) { continue; } err = bpf_map__unpin(map, pin_path); if (err) return err; } return 0; } int bpf_object__pin_programs(struct bpf_object *obj, const char *path) { struct bpf_program *prog; int err; if (!obj) return -ENOENT; if (!obj->loaded) { pr_warn("object not yet loaded; load it first\n"); return -ENOENT; } bpf_object__for_each_program(prog, obj) { char buf[PATH_MAX]; int len; len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->pin_name); if (len < 0) { err = -EINVAL; goto err_unpin_programs; } else if (len >= PATH_MAX) { err = -ENAMETOOLONG; goto err_unpin_programs; } err = bpf_program__pin(prog, buf); if (err) goto err_unpin_programs; } return 0; err_unpin_programs: while ((prog = bpf_program__prev(prog, obj))) { char buf[PATH_MAX]; int len; len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->pin_name); if (len < 0) continue; else if (len >= PATH_MAX) continue; bpf_program__unpin(prog, buf); } return err; } int bpf_object__unpin_programs(struct bpf_object *obj, const char *path) { struct bpf_program *prog; int err; if (!obj) return -ENOENT; bpf_object__for_each_program(prog, obj) { char buf[PATH_MAX]; int len; len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->pin_name); if (len < 0) return -EINVAL; else if (len >= PATH_MAX) return -ENAMETOOLONG; err = bpf_program__unpin(prog, buf); if (err) return err; } return 0; } int bpf_object__pin(struct bpf_object *obj, const char *path) { int err; err = bpf_object__pin_maps(obj, path); if (err) return err; err = bpf_object__pin_programs(obj, path); if (err) { bpf_object__unpin_maps(obj, path); return err; } return 0; } static void bpf_map__destroy(struct bpf_map *map) { if (map->clear_priv) map->clear_priv(map, map->priv); map->priv = NULL; map->clear_priv = NULL; if (map->inner_map) { bpf_map__destroy(map->inner_map); zfree(&map->inner_map); } zfree(&map->init_slots); map->init_slots_sz = 0; if (map->mmaped) { munmap(map->mmaped, bpf_map_mmap_sz(map)); map->mmaped = NULL; } if (map->st_ops) { zfree(&map->st_ops->data); zfree(&map->st_ops->progs); zfree(&map->st_ops->kern_func_off); zfree(&map->st_ops); } zfree(&map->name); zfree(&map->pin_path); if (map->fd >= 0) zclose(map->fd); } void bpf_object__close(struct bpf_object *obj) { size_t i; if (IS_ERR_OR_NULL(obj)) return; if (obj->clear_priv) obj->clear_priv(obj, obj->priv); bpf_object__elf_finish(obj); bpf_object__unload(obj); btf__free(obj->btf); btf_ext__free(obj->btf_ext); for (i = 0; i < obj->nr_maps; i++) bpf_map__destroy(&obj->maps[i]); zfree(&obj->kconfig); zfree(&obj->externs); obj->nr_extern = 0; zfree(&obj->maps); obj->nr_maps = 0; if (obj->programs && obj->nr_programs) { for (i = 0; i < obj->nr_programs; i++) bpf_program__exit(&obj->programs[i]); } zfree(&obj->programs); list_del(&obj->list); free(obj); } struct bpf_object * bpf_object__next(struct bpf_object *prev) { struct bpf_object *next; if (!prev) next = list_first_entry(&bpf_objects_list, struct bpf_object, list); else next = list_next_entry(prev, list); /* Empty list is noticed here so don't need checking on entry. */ if (&next->list == &bpf_objects_list) return NULL; return next; } const char *bpf_object__name(const struct bpf_object *obj) { return obj ? obj->name : ERR_PTR(-EINVAL); } unsigned int bpf_object__kversion(const struct bpf_object *obj) { return obj ? obj->kern_version : 0; } struct btf *bpf_object__btf(const struct bpf_object *obj) { return obj ? obj->btf : NULL; } int bpf_object__btf_fd(const struct bpf_object *obj) { return obj->btf ? btf__fd(obj->btf) : -1; } int bpf_object__set_kversion(struct bpf_object *obj, __u32 kern_version) { if (obj->loaded) return -EINVAL; obj->kern_version = kern_version; return 0; } int bpf_object__set_priv(struct bpf_object *obj, void *priv, bpf_object_clear_priv_t clear_priv) { if (obj->priv && obj->clear_priv) obj->clear_priv(obj, obj->priv); obj->priv = priv; obj->clear_priv = clear_priv; return 0; } void *bpf_object__priv(const struct bpf_object *obj) { return obj ? obj->priv : ERR_PTR(-EINVAL); } static struct bpf_program * __bpf_program__iter(const struct bpf_program *p, const struct bpf_object *obj, bool forward) { size_t nr_programs = obj->nr_programs; ssize_t idx; if (!nr_programs) return NULL; if (!p) /* Iter from the beginning */ return forward ? &obj->programs[0] : &obj->programs[nr_programs - 1]; if (p->obj != obj) { pr_warn("error: program handler doesn't match object\n"); return NULL; } idx = (p - obj->programs) + (forward ? 1 : -1); if (idx >= obj->nr_programs || idx < 0) return NULL; return &obj->programs[idx]; } struct bpf_program * bpf_program__next(struct bpf_program *prev, const struct bpf_object *obj) { struct bpf_program *prog = prev; do { prog = __bpf_program__iter(prog, obj, true); } while (prog && prog_is_subprog(obj, prog)); return prog; } struct bpf_program * bpf_program__prev(struct bpf_program *next, const struct bpf_object *obj) { struct bpf_program *prog = next; do { prog = __bpf_program__iter(prog, obj, false); } while (prog && prog_is_subprog(obj, prog)); return prog; } int bpf_program__set_priv(struct bpf_program *prog, void *priv, bpf_program_clear_priv_t clear_priv) { if (prog->priv && prog->clear_priv) prog->clear_priv(prog, prog->priv); prog->priv = priv; prog->clear_priv = clear_priv; return 0; } void *bpf_program__priv(const struct bpf_program *prog) { return prog ? prog->priv : ERR_PTR(-EINVAL); } void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex) { prog->prog_ifindex = ifindex; } const char *bpf_program__name(const struct bpf_program *prog) { return prog->name; } const char *bpf_program__section_name(const struct bpf_program *prog) { return prog->sec_name; } const char *bpf_program__title(const struct bpf_program *prog, bool needs_copy) { const char *title; title = prog->sec_name; if (needs_copy) { title = strdup(title); if (!title) { pr_warn("failed to strdup program title\n"); return ERR_PTR(-ENOMEM); } } return title; } bool bpf_program__autoload(const struct bpf_program *prog) { return prog->load; } int bpf_program__set_autoload(struct bpf_program *prog, bool autoload) { if (prog->obj->loaded) return -EINVAL; prog->load = autoload; return 0; } int bpf_program__fd(const struct bpf_program *prog) { return bpf_program__nth_fd(prog, 0); } size_t bpf_program__size(const struct bpf_program *prog) { return prog->insns_cnt * BPF_INSN_SZ; } int bpf_program__set_prep(struct bpf_program *prog, int nr_instances, bpf_program_prep_t prep) { int *instances_fds; if (nr_instances <= 0 || !prep) return -EINVAL; if (prog->instances.nr > 0 || prog->instances.fds) { pr_warn("Can't set pre-processor after loading\n"); return -EINVAL; } instances_fds = malloc(sizeof(int) * nr_instances); if (!instances_fds) { pr_warn("alloc memory failed for fds\n"); return -ENOMEM; } /* fill all fd with -1 */ memset(instances_fds, -1, sizeof(int) * nr_instances); prog->instances.nr = nr_instances; prog->instances.fds = instances_fds; prog->preprocessor = prep; return 0; } int bpf_program__nth_fd(const struct bpf_program *prog, int n) { int fd; if (!prog) return -EINVAL; if (n >= prog->instances.nr || n < 0) { pr_warn("Can't get the %dth fd from program %s: only %d instances\n", n, prog->name, prog->instances.nr); return -EINVAL; } fd = prog->instances.fds[n]; if (fd < 0) { pr_warn("%dth instance of program '%s' is invalid\n", n, prog->name); return -ENOENT; } return fd; } enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog) { return prog->type; } void bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type) { prog->type = type; } static bool bpf_program__is_type(const struct bpf_program *prog, enum bpf_prog_type type) { return prog ? (prog->type == type) : false; } #define BPF_PROG_TYPE_FNS(NAME, TYPE) \ int bpf_program__set_##NAME(struct bpf_program *prog) \ { \ if (!prog) \ return -EINVAL; \ bpf_program__set_type(prog, TYPE); \ return 0; \ } \ \ bool bpf_program__is_##NAME(const struct bpf_program *prog) \ { \ return bpf_program__is_type(prog, TYPE); \ } \ BPF_PROG_TYPE_FNS(socket_filter, BPF_PROG_TYPE_SOCKET_FILTER); BPF_PROG_TYPE_FNS(lsm, BPF_PROG_TYPE_LSM); BPF_PROG_TYPE_FNS(kprobe, BPF_PROG_TYPE_KPROBE); BPF_PROG_TYPE_FNS(sched_cls, BPF_PROG_TYPE_SCHED_CLS); BPF_PROG_TYPE_FNS(sched_act, BPF_PROG_TYPE_SCHED_ACT); BPF_PROG_TYPE_FNS(tracepoint, BPF_PROG_TYPE_TRACEPOINT); BPF_PROG_TYPE_FNS(raw_tracepoint, BPF_PROG_TYPE_RAW_TRACEPOINT); BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP); BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT); BPF_PROG_TYPE_FNS(tracing, BPF_PROG_TYPE_TRACING); BPF_PROG_TYPE_FNS(struct_ops, BPF_PROG_TYPE_STRUCT_OPS); BPF_PROG_TYPE_FNS(extension, BPF_PROG_TYPE_EXT); BPF_PROG_TYPE_FNS(sk_lookup, BPF_PROG_TYPE_SK_LOOKUP); enum bpf_attach_type bpf_program__get_expected_attach_type(const struct bpf_program *prog) { return prog->expected_attach_type; } void bpf_program__set_expected_attach_type(struct bpf_program *prog, enum bpf_attach_type type) { prog->expected_attach_type = type; } #define BPF_PROG_SEC_IMPL(string, ptype, eatype, eatype_optional, \ attachable, attach_btf) \ { \ .sec = string, \ .len = sizeof(string) - 1, \ .prog_type = ptype, \ .expected_attach_type = eatype, \ .is_exp_attach_type_optional = eatype_optional, \ .is_attachable = attachable, \ .is_attach_btf = attach_btf, \ } /* Programs that can NOT be attached. */ #define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_IMPL(string, ptype, 0, 0, 0, 0) /* Programs that can be attached. */ #define BPF_APROG_SEC(string, ptype, atype) \ BPF_PROG_SEC_IMPL(string, ptype, atype, true, 1, 0) /* Programs that must specify expected attach type at load time. */ #define BPF_EAPROG_SEC(string, ptype, eatype) \ BPF_PROG_SEC_IMPL(string, ptype, eatype, false, 1, 0) /* Programs that use BTF to identify attach point */ #define BPF_PROG_BTF(string, ptype, eatype) \ BPF_PROG_SEC_IMPL(string, ptype, eatype, false, 0, 1) /* Programs that can be attached but attach type can't be identified by section * name. Kept for backward compatibility. */ #define BPF_APROG_COMPAT(string, ptype) BPF_PROG_SEC(string, ptype) #define SEC_DEF(sec_pfx, ptype, ...) { \ .sec = sec_pfx, \ .len = sizeof(sec_pfx) - 1, \ .prog_type = BPF_PROG_TYPE_##ptype, \ __VA_ARGS__ \ } static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec, struct bpf_program *prog); static struct bpf_link *attach_tp(const struct bpf_sec_def *sec, struct bpf_program *prog); static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec, struct bpf_program *prog); static struct bpf_link *attach_trace(const struct bpf_sec_def *sec, struct bpf_program *prog); static struct bpf_link *attach_lsm(const struct bpf_sec_def *sec, struct bpf_program *prog); static struct bpf_link *attach_iter(const struct bpf_sec_def *sec, struct bpf_program *prog); static const struct bpf_sec_def section_defs[] = { BPF_PROG_SEC("socket", BPF_PROG_TYPE_SOCKET_FILTER), BPF_PROG_SEC("sk_reuseport", BPF_PROG_TYPE_SK_REUSEPORT), SEC_DEF("kprobe/", KPROBE, .attach_fn = attach_kprobe), BPF_PROG_SEC("uprobe/", BPF_PROG_TYPE_KPROBE), SEC_DEF("kretprobe/", KPROBE, .attach_fn = attach_kprobe), BPF_PROG_SEC("uretprobe/", BPF_PROG_TYPE_KPROBE), BPF_PROG_SEC("classifier", BPF_PROG_TYPE_SCHED_CLS), BPF_PROG_SEC("action", BPF_PROG_TYPE_SCHED_ACT), SEC_DEF("tracepoint/", TRACEPOINT, .attach_fn = attach_tp), SEC_DEF("tp/", TRACEPOINT, .attach_fn = attach_tp), SEC_DEF("raw_tracepoint/", RAW_TRACEPOINT, .attach_fn = attach_raw_tp), SEC_DEF("raw_tp/", RAW_TRACEPOINT, .attach_fn = attach_raw_tp), SEC_DEF("tp_btf/", TRACING, .expected_attach_type = BPF_TRACE_RAW_TP, .is_attach_btf = true, .attach_fn = attach_trace), SEC_DEF("fentry/", TRACING, .expected_attach_type = BPF_TRACE_FENTRY, .is_attach_btf = true, .attach_fn = attach_trace), SEC_DEF("fmod_ret/", TRACING, .expected_attach_type = BPF_MODIFY_RETURN, .is_attach_btf = true, .attach_fn = attach_trace), SEC_DEF("fexit/", TRACING, .expected_attach_type = BPF_TRACE_FEXIT, .is_attach_btf = true, .attach_fn = attach_trace), SEC_DEF("fentry.s/", TRACING, .expected_attach_type = BPF_TRACE_FENTRY, .is_attach_btf = true, .is_sleepable = true, .attach_fn = attach_trace), SEC_DEF("fmod_ret.s/", TRACING, .expected_attach_type = BPF_MODIFY_RETURN, .is_attach_btf = true, .is_sleepable = true, .attach_fn = attach_trace), SEC_DEF("fexit.s/", TRACING, .expected_attach_type = BPF_TRACE_FEXIT, .is_attach_btf = true, .is_sleepable = true, .attach_fn = attach_trace), SEC_DEF("freplace/", EXT, .is_attach_btf = true, .attach_fn = attach_trace), SEC_DEF("lsm/", LSM, .is_attach_btf = true, .expected_attach_type = BPF_LSM_MAC, .attach_fn = attach_lsm), SEC_DEF("lsm.s/", LSM, .is_attach_btf = true, .is_sleepable = true, .expected_attach_type = BPF_LSM_MAC, .attach_fn = attach_lsm), SEC_DEF("iter/", TRACING, .expected_attach_type = BPF_TRACE_ITER, .is_attach_btf = true, .attach_fn = attach_iter), BPF_EAPROG_SEC("xdp_devmap/", BPF_PROG_TYPE_XDP, BPF_XDP_DEVMAP), BPF_EAPROG_SEC("xdp_cpumap/", BPF_PROG_TYPE_XDP, BPF_XDP_CPUMAP), BPF_APROG_SEC("xdp", BPF_PROG_TYPE_XDP, BPF_XDP), BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT), BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN), BPF_PROG_SEC("lwt_out", BPF_PROG_TYPE_LWT_OUT), BPF_PROG_SEC("lwt_xmit", BPF_PROG_TYPE_LWT_XMIT), BPF_PROG_SEC("lwt_seg6local", BPF_PROG_TYPE_LWT_SEG6LOCAL), BPF_APROG_SEC("cgroup_skb/ingress", BPF_PROG_TYPE_CGROUP_SKB, BPF_CGROUP_INET_INGRESS), BPF_APROG_SEC("cgroup_skb/egress", BPF_PROG_TYPE_CGROUP_SKB, BPF_CGROUP_INET_EGRESS), BPF_APROG_COMPAT("cgroup/skb", BPF_PROG_TYPE_CGROUP_SKB), BPF_EAPROG_SEC("cgroup/sock_create", BPF_PROG_TYPE_CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE), BPF_EAPROG_SEC("cgroup/sock_release", BPF_PROG_TYPE_CGROUP_SOCK, BPF_CGROUP_INET_SOCK_RELEASE), BPF_APROG_SEC("cgroup/sock", BPF_PROG_TYPE_CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE), BPF_EAPROG_SEC("cgroup/post_bind4", BPF_PROG_TYPE_CGROUP_SOCK, BPF_CGROUP_INET4_POST_BIND), BPF_EAPROG_SEC("cgroup/post_bind6", BPF_PROG_TYPE_CGROUP_SOCK, BPF_CGROUP_INET6_POST_BIND), BPF_APROG_SEC("cgroup/dev", BPF_PROG_TYPE_CGROUP_DEVICE, BPF_CGROUP_DEVICE), BPF_APROG_SEC("sockops", BPF_PROG_TYPE_SOCK_OPS, BPF_CGROUP_SOCK_OPS), BPF_APROG_SEC("sk_skb/stream_parser", BPF_PROG_TYPE_SK_SKB, BPF_SK_SKB_STREAM_PARSER), BPF_APROG_SEC("sk_skb/stream_verdict", BPF_PROG_TYPE_SK_SKB, BPF_SK_SKB_STREAM_VERDICT), BPF_APROG_COMPAT("sk_skb", BPF_PROG_TYPE_SK_SKB), BPF_APROG_SEC("sk_msg", BPF_PROG_TYPE_SK_MSG, BPF_SK_MSG_VERDICT), BPF_APROG_SEC("lirc_mode2", BPF_PROG_TYPE_LIRC_MODE2, BPF_LIRC_MODE2), BPF_APROG_SEC("flow_dissector", BPF_PROG_TYPE_FLOW_DISSECTOR, BPF_FLOW_DISSECTOR), BPF_EAPROG_SEC("cgroup/bind4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_BIND), BPF_EAPROG_SEC("cgroup/bind6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_BIND), BPF_EAPROG_SEC("cgroup/connect4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_CONNECT), BPF_EAPROG_SEC("cgroup/connect6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_CONNECT), BPF_EAPROG_SEC("cgroup/sendmsg4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_SENDMSG), BPF_EAPROG_SEC("cgroup/sendmsg6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_SENDMSG), BPF_EAPROG_SEC("cgroup/recvmsg4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_RECVMSG), BPF_EAPROG_SEC("cgroup/recvmsg6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_RECVMSG), BPF_EAPROG_SEC("cgroup/getpeername4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETPEERNAME), BPF_EAPROG_SEC("cgroup/getpeername6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETPEERNAME), BPF_EAPROG_SEC("cgroup/getsockname4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETSOCKNAME), BPF_EAPROG_SEC("cgroup/getsockname6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETSOCKNAME), BPF_EAPROG_SEC("cgroup/sysctl", BPF_PROG_TYPE_CGROUP_SYSCTL, BPF_CGROUP_SYSCTL), BPF_EAPROG_SEC("cgroup/getsockopt", BPF_PROG_TYPE_CGROUP_SOCKOPT, BPF_CGROUP_GETSOCKOPT), BPF_EAPROG_SEC("cgroup/setsockopt", BPF_PROG_TYPE_CGROUP_SOCKOPT, BPF_CGROUP_SETSOCKOPT), BPF_PROG_SEC("struct_ops", BPF_PROG_TYPE_STRUCT_OPS), BPF_EAPROG_SEC("sk_lookup/", BPF_PROG_TYPE_SK_LOOKUP, BPF_SK_LOOKUP), }; #undef BPF_PROG_SEC_IMPL #undef BPF_PROG_SEC #undef BPF_APROG_SEC #undef BPF_EAPROG_SEC #undef BPF_APROG_COMPAT #undef SEC_DEF #define MAX_TYPE_NAME_SIZE 32 static const struct bpf_sec_def *find_sec_def(const char *sec_name) { int i, n = ARRAY_SIZE(section_defs); for (i = 0; i < n; i++) { if (strncmp(sec_name, section_defs[i].sec, section_defs[i].len)) continue; return §ion_defs[i]; } return NULL; } static char *libbpf_get_type_names(bool attach_type) { int i, len = ARRAY_SIZE(section_defs) * MAX_TYPE_NAME_SIZE; char *buf; buf = malloc(len); if (!buf) return NULL; buf[0] = '\0'; /* Forge string buf with all available names */ for (i = 0; i < ARRAY_SIZE(section_defs); i++) { if (attach_type && !section_defs[i].is_attachable) continue; if (strlen(buf) + strlen(section_defs[i].sec) + 2 > len) { free(buf); return NULL; } strcat(buf, " "); strcat(buf, section_defs[i].sec); } return buf; } int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type, enum bpf_attach_type *expected_attach_type) { const struct bpf_sec_def *sec_def; char *type_names; if (!name) return -EINVAL; sec_def = find_sec_def(name); if (sec_def) { *prog_type = sec_def->prog_type; *expected_attach_type = sec_def->expected_attach_type; return 0; } pr_debug("failed to guess program type from ELF section '%s'\n", name); type_names = libbpf_get_type_names(false); if (type_names != NULL) { pr_debug("supported section(type) names are:%s\n", type_names); free(type_names); } return -ESRCH; } static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj, size_t offset) { struct bpf_map *map; size_t i; for (i = 0; i < obj->nr_maps; i++) { map = &obj->maps[i]; if (!bpf_map__is_struct_ops(map)) continue; if (map->sec_offset <= offset && offset - map->sec_offset < map->def.value_size) return map; } return NULL; } /* Collect the reloc from ELF and populate the st_ops->progs[] */ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data) { const struct btf_member *member; struct bpf_struct_ops *st_ops; struct bpf_program *prog; unsigned int shdr_idx; const struct btf *btf; struct bpf_map *map; Elf_Data *symbols; unsigned int moff, insn_idx; const char *name; __u32 member_idx; GElf_Sym sym; GElf_Rel rel; int i, nrels; symbols = obj->efile.symbols; btf = obj->btf; nrels = shdr->sh_size / shdr->sh_entsize; for (i = 0; i < nrels; i++) { if (!gelf_getrel(data, i, &rel)) { pr_warn("struct_ops reloc: failed to get %d reloc\n", i); return -LIBBPF_ERRNO__FORMAT; } if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) { pr_warn("struct_ops reloc: symbol %zx not found\n", (size_t)GELF_R_SYM(rel.r_info)); return -LIBBPF_ERRNO__FORMAT; } name = elf_sym_str(obj, sym.st_name) ?: ""; map = find_struct_ops_map_by_offset(obj, rel.r_offset); if (!map) { pr_warn("struct_ops reloc: cannot find map at rel.r_offset %zu\n", (size_t)rel.r_offset); return -EINVAL; } moff = rel.r_offset - map->sec_offset; shdr_idx = sym.st_shndx; st_ops = map->st_ops; pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel.r_offset %zu map->sec_offset %zu name %d (\'%s\')\n", map->name, (long long)(rel.r_info >> 32), (long long)sym.st_value, shdr_idx, (size_t)rel.r_offset, map->sec_offset, sym.st_name, name); if (shdr_idx >= SHN_LORESERVE) { pr_warn("struct_ops reloc %s: rel.r_offset %zu shdr_idx %u unsupported non-static function\n", map->name, (size_t)rel.r_offset, shdr_idx); return -LIBBPF_ERRNO__RELOC; } if (sym.st_value % BPF_INSN_SZ) { pr_warn("struct_ops reloc %s: invalid target program offset %llu\n", map->name, (unsigned long long)sym.st_value); return -LIBBPF_ERRNO__FORMAT; } insn_idx = sym.st_value / BPF_INSN_SZ; member = find_member_by_offset(st_ops->type, moff * 8); if (!member) { pr_warn("struct_ops reloc %s: cannot find member at moff %u\n", map->name, moff); return -EINVAL; } member_idx = member - btf_members(st_ops->type); name = btf__name_by_offset(btf, member->name_off); if (!resolve_func_ptr(btf, member->type, NULL)) { pr_warn("struct_ops reloc %s: cannot relocate non func ptr %s\n", map->name, name); return -EINVAL; } prog = find_prog_by_sec_insn(obj, shdr_idx, insn_idx); if (!prog) { pr_warn("struct_ops reloc %s: cannot find prog at shdr_idx %u to relocate func ptr %s\n", map->name, shdr_idx, name); return -EINVAL; } if (prog->type == BPF_PROG_TYPE_UNSPEC) { const struct bpf_sec_def *sec_def; sec_def = find_sec_def(prog->sec_name); if (sec_def && sec_def->prog_type != BPF_PROG_TYPE_STRUCT_OPS) { /* for pr_warn */ prog->type = sec_def->prog_type; goto invalid_prog; } prog->type = BPF_PROG_TYPE_STRUCT_OPS; prog->attach_btf_id = st_ops->type_id; prog->expected_attach_type = member_idx; } else if (prog->type != BPF_PROG_TYPE_STRUCT_OPS || prog->attach_btf_id != st_ops->type_id || prog->expected_attach_type != member_idx) { goto invalid_prog; } st_ops->progs[member_idx] = prog; } return 0; invalid_prog: pr_warn("struct_ops reloc %s: cannot use prog %s in sec %s with type %u attach_btf_id %u expected_attach_type %u for func ptr %s\n", map->name, prog->name, prog->sec_name, prog->type, prog->attach_btf_id, prog->expected_attach_type, name); return -EINVAL; } #define BTF_TRACE_PREFIX "btf_trace_" #define BTF_LSM_PREFIX "bpf_lsm_" #define BTF_ITER_PREFIX "bpf_iter_" #define BTF_MAX_NAME_SIZE 128 static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix, const char *name, __u32 kind) { char btf_type_name[BTF_MAX_NAME_SIZE]; int ret; ret = snprintf(btf_type_name, sizeof(btf_type_name), "%s%s", prefix, name); /* snprintf returns the number of characters written excluding the * the terminating null. So, if >= BTF_MAX_NAME_SIZE are written, it * indicates truncation. */ if (ret < 0 || ret >= sizeof(btf_type_name)) return -ENAMETOOLONG; return btf__find_by_name_kind(btf, btf_type_name, kind); } static inline int find_attach_btf_id(struct btf *btf, const char *name, enum bpf_attach_type attach_type) { int err; if (attach_type == BPF_TRACE_RAW_TP) err = find_btf_by_prefix_kind(btf, BTF_TRACE_PREFIX, name, BTF_KIND_TYPEDEF); else if (attach_type == BPF_LSM_MAC) err = find_btf_by_prefix_kind(btf, BTF_LSM_PREFIX, name, BTF_KIND_FUNC); else if (attach_type == BPF_TRACE_ITER) err = find_btf_by_prefix_kind(btf, BTF_ITER_PREFIX, name, BTF_KIND_FUNC); else err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); return err; } int libbpf_find_vmlinux_btf_id(const char *name, enum bpf_attach_type attach_type) { struct btf *btf; int err; btf = libbpf_find_kernel_btf(); if (IS_ERR(btf)) { pr_warn("vmlinux BTF is not found\n"); return -EINVAL; } err = find_attach_btf_id(btf, name, attach_type); if (err <= 0) pr_warn("%s is not found in vmlinux BTF\n", name); btf__free(btf); return err; } static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) { struct bpf_prog_info_linear *info_linear; struct bpf_prog_info *info; struct btf *btf = NULL; int err = -EINVAL; info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0); if (IS_ERR_OR_NULL(info_linear)) { pr_warn("failed get_prog_info_linear for FD %d\n", attach_prog_fd); return -EINVAL; } info = &info_linear->info; if (!info->btf_id) { pr_warn("The target program doesn't have BTF\n"); goto out; } if (btf__get_from_id(info->btf_id, &btf)) { pr_warn("Failed to get BTF of the program\n"); goto out; } err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); btf__free(btf); if (err <= 0) { pr_warn("%s is not found in prog's BTF\n", name); goto out; } out: free(info_linear); return err; } static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name, enum bpf_attach_type attach_type, int *btf_obj_fd, int *btf_type_id) { int ret, i; ret = find_attach_btf_id(obj->btf_vmlinux, attach_name, attach_type); if (ret > 0) { *btf_obj_fd = 0; /* vmlinux BTF */ *btf_type_id = ret; return 0; } if (ret != -ENOENT) return ret; ret = load_module_btfs(obj); if (ret) return ret; for (i = 0; i < obj->btf_module_cnt; i++) { const struct module_btf *mod = &obj->btf_modules[i]; ret = find_attach_btf_id(mod->btf, attach_name, attach_type); if (ret > 0) { *btf_obj_fd = mod->fd; *btf_type_id = ret; return 0; } if (ret == -ENOENT) continue; return ret; } return -ESRCH; } static int libbpf_find_attach_btf_id(struct bpf_program *prog, int *btf_obj_fd, int *btf_type_id) { enum bpf_attach_type attach_type = prog->expected_attach_type; __u32 attach_prog_fd = prog->attach_prog_fd; const char *name = prog->sec_name, *attach_name; const struct bpf_sec_def *sec = NULL; int i, err; if (!name) return -EINVAL; for (i = 0; i < ARRAY_SIZE(section_defs); i++) { if (!section_defs[i].is_attach_btf) continue; if (strncmp(name, section_defs[i].sec, section_defs[i].len)) continue; sec = §ion_defs[i]; break; } if (!sec) { pr_warn("failed to identify BTF ID based on ELF section name '%s'\n", name); return -ESRCH; } attach_name = name + sec->len; /* BPF program's BTF ID */ if (attach_prog_fd) { err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd); if (err < 0) { pr_warn("failed to find BPF program (FD %d) BTF ID for '%s': %d\n", attach_prog_fd, attach_name, err); return err; } *btf_obj_fd = 0; *btf_type_id = err; return 0; } /* kernel/module BTF ID */ err = find_kernel_btf_id(prog->obj, attach_name, attach_type, btf_obj_fd, btf_type_id); if (err) { pr_warn("failed to find kernel BTF type ID of '%s': %d\n", attach_name, err); return err; } return 0; } int libbpf_attach_type_by_name(const char *name, enum bpf_attach_type *attach_type) { char *type_names; int i; if (!name) return -EINVAL; for (i = 0; i < ARRAY_SIZE(section_defs); i++) { if (strncmp(name, section_defs[i].sec, section_defs[i].len)) continue; if (!section_defs[i].is_attachable) return -EINVAL; *attach_type = section_defs[i].expected_attach_type; return 0; } pr_debug("failed to guess attach type based on ELF section name '%s'\n", name); type_names = libbpf_get_type_names(true); if (type_names != NULL) { pr_debug("attachable section(type) names are:%s\n", type_names); free(type_names); } return -EINVAL; } int bpf_map__fd(const struct bpf_map *map) { return map ? map->fd : -EINVAL; } const struct bpf_map_def *bpf_map__def(const struct bpf_map *map) { return map ? &map->def : ERR_PTR(-EINVAL); } const char *bpf_map__name(const struct bpf_map *map) { return map ? map->name : NULL; } enum bpf_map_type bpf_map__type(const struct bpf_map *map) { return map->def.type; } int bpf_map__set_type(struct bpf_map *map, enum bpf_map_type type) { if (map->fd >= 0) return -EBUSY; map->def.type = type; return 0; } __u32 bpf_map__map_flags(const struct bpf_map *map) { return map->def.map_flags; } int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags) { if (map->fd >= 0) return -EBUSY; map->def.map_flags = flags; return 0; } __u32 bpf_map__numa_node(const struct bpf_map *map) { return map->numa_node; } int bpf_map__set_numa_node(struct bpf_map *map, __u32 numa_node) { if (map->fd >= 0) return -EBUSY; map->numa_node = numa_node; return 0; } __u32 bpf_map__key_size(const struct bpf_map *map) { return map->def.key_size; } int bpf_map__set_key_size(struct bpf_map *map, __u32 size) { if (map->fd >= 0) return -EBUSY; map->def.key_size = size; return 0; } __u32 bpf_map__value_size(const struct bpf_map *map) { return map->def.value_size; } int bpf_map__set_value_size(struct bpf_map *map, __u32 size) { if (map->fd >= 0) return -EBUSY; map->def.value_size = size; return 0; } __u32 bpf_map__btf_key_type_id(const struct bpf_map *map) { return map ? map->btf_key_type_id : 0; } __u32 bpf_map__btf_value_type_id(const struct bpf_map *map) { return map ? map->btf_value_type_id : 0; } int bpf_map__set_priv(struct bpf_map *map, void *priv, bpf_map_clear_priv_t clear_priv) { if (!map) return -EINVAL; if (map->priv) { if (map->clear_priv) map->clear_priv(map, map->priv); } map->priv = priv; map->clear_priv = clear_priv; return 0; } void *bpf_map__priv(const struct bpf_map *map) { return map ? map->priv : ERR_PTR(-EINVAL); } int bpf_map__set_initial_value(struct bpf_map *map, const void *data, size_t size) { if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG || size != map->def.value_size || map->fd >= 0) return -EINVAL; memcpy(map->mmaped, data, size); return 0; } bool bpf_map__is_offload_neutral(const struct bpf_map *map) { return map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY; } bool bpf_map__is_internal(const struct bpf_map *map) { return map->libbpf_type != LIBBPF_MAP_UNSPEC; } __u32 bpf_map__ifindex(const struct bpf_map *map) { return map->map_ifindex; } int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex) { if (map->fd >= 0) return -EBUSY; map->map_ifindex = ifindex; return 0; } int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd) { if (!bpf_map_type__is_map_in_map(map->def.type)) { pr_warn("error: unsupported map type\n"); return -EINVAL; } if (map->inner_map_fd != -1) { pr_warn("error: inner_map_fd already specified\n"); return -EINVAL; } zfree(&map->inner_map); map->inner_map_fd = fd; return 0; } static struct bpf_map * __bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i) { ssize_t idx; struct bpf_map *s, *e; if (!obj || !obj->maps) return NULL; s = obj->maps; e = obj->maps + obj->nr_maps; if ((m < s) || (m >= e)) { pr_warn("error in %s: map handler doesn't belong to object\n", __func__); return NULL; } idx = (m - obj->maps) + i; if (idx >= obj->nr_maps || idx < 0) return NULL; return &obj->maps[idx]; } struct bpf_map * bpf_map__next(const struct bpf_map *prev, const struct bpf_object *obj) { if (prev == NULL) return obj->maps; return __bpf_map__iter(prev, obj, 1); } struct bpf_map * bpf_map__prev(const struct bpf_map *next, const struct bpf_object *obj) { if (next == NULL) { if (!obj->nr_maps) return NULL; return obj->maps + obj->nr_maps - 1; } return __bpf_map__iter(next, obj, -1); } struct bpf_map * bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name) { struct bpf_map *pos; bpf_object__for_each_map(pos, obj) { if (pos->name && !strcmp(pos->name, name)) return pos; } return NULL; } int bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name) { return bpf_map__fd(bpf_object__find_map_by_name(obj, name)); } struct bpf_map * bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset) { return ERR_PTR(-ENOTSUP); } long libbpf_get_error(const void *ptr) { return PTR_ERR_OR_ZERO(ptr); } int bpf_prog_load(const char *file, enum bpf_prog_type type, struct bpf_object **pobj, int *prog_fd) { struct bpf_prog_load_attr attr; memset(&attr, 0, sizeof(struct bpf_prog_load_attr)); attr.file = file; attr.prog_type = type; attr.expected_attach_type = 0; return bpf_prog_load_xattr(&attr, pobj, prog_fd); } int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, struct bpf_object **pobj, int *prog_fd) { struct bpf_object_open_attr open_attr = {}; struct bpf_program *prog, *first_prog = NULL; struct bpf_object *obj; struct bpf_map *map; int err; if (!attr) return -EINVAL; if (!attr->file) return -EINVAL; open_attr.file = attr->file; open_attr.prog_type = attr->prog_type; obj = bpf_object__open_xattr(&open_attr); if (IS_ERR_OR_NULL(obj)) return -ENOENT; bpf_object__for_each_program(prog, obj) { enum bpf_attach_type attach_type = attr->expected_attach_type; /* * to preserve backwards compatibility, bpf_prog_load treats * attr->prog_type, if specified, as an override to whatever * bpf_object__open guessed */ if (attr->prog_type != BPF_PROG_TYPE_UNSPEC) { bpf_program__set_type(prog, attr->prog_type); bpf_program__set_expected_attach_type(prog, attach_type); } if (bpf_program__get_type(prog) == BPF_PROG_TYPE_UNSPEC) { /* * we haven't guessed from section name and user * didn't provide a fallback type, too bad... */ bpf_object__close(obj); return -EINVAL; } prog->prog_ifindex = attr->ifindex; prog->log_level = attr->log_level; prog->prog_flags |= attr->prog_flags; if (!first_prog) first_prog = prog; } bpf_object__for_each_map(map, obj) { if (!bpf_map__is_offload_neutral(map)) map->map_ifindex = attr->ifindex; } if (!first_prog) { pr_warn("object file doesn't contain bpf program\n"); bpf_object__close(obj); return -ENOENT; } err = bpf_object__load(obj); if (err) { bpf_object__close(obj); return err; } *pobj = obj; *prog_fd = bpf_program__fd(first_prog); return 0; } struct bpf_link { int (*detach)(struct bpf_link *link); int (*destroy)(struct bpf_link *link); char *pin_path; /* NULL, if not pinned */ int fd; /* hook FD, -1 if not applicable */ bool disconnected; }; /* Replace link's underlying BPF program with the new one */ int bpf_link__update_program(struct bpf_link *link, struct bpf_program *prog) { return bpf_link_update(bpf_link__fd(link), bpf_program__fd(prog), NULL); } /* Release "ownership" of underlying BPF resource (typically, BPF program * attached to some BPF hook, e.g., tracepoint, kprobe, etc). Disconnected * link, when destructed through bpf_link__destroy() call won't attempt to * detach/unregisted that BPF resource. This is useful in situations where, * say, attached BPF program has to outlive userspace program that attached it * in the system. Depending on type of BPF program, though, there might be * additional steps (like pinning BPF program in BPF FS) necessary to ensure * exit of userspace program doesn't trigger automatic detachment and clean up * inside the kernel. */ void bpf_link__disconnect(struct bpf_link *link) { link->disconnected = true; } int bpf_link__destroy(struct bpf_link *link) { int err = 0; if (IS_ERR_OR_NULL(link)) return 0; if (!link->disconnected && link->detach) err = link->detach(link); if (link->destroy) link->destroy(link); if (link->pin_path) free(link->pin_path); free(link); return err; } int bpf_link__fd(const struct bpf_link *link) { return link->fd; } const char *bpf_link__pin_path(const struct bpf_link *link) { return link->pin_path; } static int bpf_link__detach_fd(struct bpf_link *link) { return close(link->fd); } struct bpf_link *bpf_link__open(const char *path) { struct bpf_link *link; int fd; fd = bpf_obj_get(path); if (fd < 0) { fd = -errno; pr_warn("failed to open link at %s: %d\n", path, fd); return ERR_PTR(fd); } link = calloc(1, sizeof(*link)); if (!link) { close(fd); return ERR_PTR(-ENOMEM); } link->detach = &bpf_link__detach_fd; link->fd = fd; link->pin_path = strdup(path); if (!link->pin_path) { bpf_link__destroy(link); return ERR_PTR(-ENOMEM); } return link; } int bpf_link__detach(struct bpf_link *link) { return bpf_link_detach(link->fd) ? -errno : 0; } int bpf_link__pin(struct bpf_link *link, const char *path) { int err; if (link->pin_path) return -EBUSY; err = make_parent_dir(path); if (err) return err; err = check_path(path); if (err) return err; link->pin_path = strdup(path); if (!link->pin_path) return -ENOMEM; if (bpf_obj_pin(link->fd, link->pin_path)) { err = -errno; zfree(&link->pin_path); return err; } pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path); return 0; } int bpf_link__unpin(struct bpf_link *link) { int err; if (!link->pin_path) return -EINVAL; err = unlink(link->pin_path); if (err != 0) return -errno; pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path); zfree(&link->pin_path); return 0; } static int bpf_link__detach_perf_event(struct bpf_link *link) { int err; err = ioctl(link->fd, PERF_EVENT_IOC_DISABLE, 0); if (err) err = -errno; close(link->fd); return err; } struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd) { char errmsg[STRERR_BUFSIZE]; struct bpf_link *link; int prog_fd, err; if (pfd < 0) { pr_warn("prog '%s': invalid perf event FD %d\n", prog->name, pfd); return ERR_PTR(-EINVAL); } prog_fd = bpf_program__fd(prog); if (prog_fd < 0) { pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n", prog->name); return ERR_PTR(-EINVAL); } link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); link->detach = &bpf_link__detach_perf_event; link->fd = pfd; if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) { err = -errno; free(link); pr_warn("prog '%s': failed to attach to pfd %d: %s\n", prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg))); if (err == -EPROTO) pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n", prog->name, pfd); return ERR_PTR(err); } if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) { err = -errno; free(link); pr_warn("prog '%s': failed to enable pfd %d: %s\n", prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg))); return ERR_PTR(err); } return link; } /* * this function is expected to parse integer in the range of [0, 2^31-1] from * given file using scanf format string fmt. If actual parsed value is * negative, the result might be indistinguishable from error */ static int parse_uint_from_file(const char *file, const char *fmt) { char buf[STRERR_BUFSIZE]; int err, ret; FILE *f; f = fopen(file, "r"); if (!f) { err = -errno; pr_debug("failed to open '%s': %s\n", file, libbpf_strerror_r(err, buf, sizeof(buf))); return err; } err = fscanf(f, fmt, &ret); if (err != 1) { err = err == EOF ? -EIO : -errno; pr_debug("failed to parse '%s': %s\n", file, libbpf_strerror_r(err, buf, sizeof(buf))); fclose(f); return err; } fclose(f); return ret; } static int determine_kprobe_perf_type(void) { const char *file = "/sys/bus/event_source/devices/kprobe/type"; return parse_uint_from_file(file, "%d\n"); } static int determine_uprobe_perf_type(void) { const char *file = "/sys/bus/event_source/devices/uprobe/type"; return parse_uint_from_file(file, "%d\n"); } static int determine_kprobe_retprobe_bit(void) { const char *file = "/sys/bus/event_source/devices/kprobe/format/retprobe"; return parse_uint_from_file(file, "config:%d\n"); } static int determine_uprobe_retprobe_bit(void) { const char *file = "/sys/bus/event_source/devices/uprobe/format/retprobe"; return parse_uint_from_file(file, "config:%d\n"); } static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name, uint64_t offset, int pid) { struct perf_event_attr attr = {}; char errmsg[STRERR_BUFSIZE]; int type, pfd, err; type = uprobe ? determine_uprobe_perf_type() : determine_kprobe_perf_type(); if (type < 0) { pr_warn("failed to determine %s perf type: %s\n", uprobe ? "uprobe" : "kprobe", libbpf_strerror_r(type, errmsg, sizeof(errmsg))); return type; } if (retprobe) { int bit = uprobe ? determine_uprobe_retprobe_bit() : determine_kprobe_retprobe_bit(); if (bit < 0) { pr_warn("failed to determine %s retprobe bit: %s\n", uprobe ? "uprobe" : "kprobe", libbpf_strerror_r(bit, errmsg, sizeof(errmsg))); return bit; } attr.config |= 1 << bit; } attr.size = sizeof(attr); attr.type = type; attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */ attr.config2 = offset; /* kprobe_addr or probe_offset */ /* pid filter is meaningful only for uprobes */ pfd = syscall(__NR_perf_event_open, &attr, pid < 0 ? -1 : pid /* pid */, pid == -1 ? 0 : -1 /* cpu */, -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC); if (pfd < 0) { err = -errno; pr_warn("%s perf_event_open() failed: %s\n", uprobe ? "uprobe" : "kprobe", libbpf_strerror_r(err, errmsg, sizeof(errmsg))); return err; } return pfd; } struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog, bool retprobe, const char *func_name) { char errmsg[STRERR_BUFSIZE]; struct bpf_link *link; int pfd, err; pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name, 0 /* offset */, -1 /* pid */); if (pfd < 0) { pr_warn("prog '%s': failed to create %s '%s' perf event: %s\n", prog->name, retprobe ? "kretprobe" : "kprobe", func_name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg))); return ERR_PTR(pfd); } link = bpf_program__attach_perf_event(prog, pfd); if (IS_ERR(link)) { close(pfd); err = PTR_ERR(link); pr_warn("prog '%s': failed to attach to %s '%s': %s\n", prog->name, retprobe ? "kretprobe" : "kprobe", func_name, libbpf_strerror_r(err, errmsg, sizeof(errmsg))); return link; } return link; } static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec, struct bpf_program *prog) { const char *func_name; bool retprobe; func_name = prog->sec_name + sec->len; retprobe = strcmp(sec->sec, "kretprobe/") == 0; return bpf_program__attach_kprobe(prog, retprobe, func_name); } struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog, bool retprobe, pid_t pid, const char *binary_path, size_t func_offset) { char errmsg[STRERR_BUFSIZE]; struct bpf_link *link; int pfd, err; pfd = perf_event_open_probe(true /* uprobe */, retprobe, binary_path, func_offset, pid); if (pfd < 0) { pr_warn("prog '%s': failed to create %s '%s:0x%zx' perf event: %s\n", prog->name, retprobe ? "uretprobe" : "uprobe", binary_path, func_offset, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg))); return ERR_PTR(pfd); } link = bpf_program__attach_perf_event(prog, pfd); if (IS_ERR(link)) { close(pfd); err = PTR_ERR(link); pr_warn("prog '%s': failed to attach to %s '%s:0x%zx': %s\n", prog->name, retprobe ? "uretprobe" : "uprobe", binary_path, func_offset, libbpf_strerror_r(err, errmsg, sizeof(errmsg))); return link; } return link; } static int determine_tracepoint_id(const char *tp_category, const char *tp_name) { char file[PATH_MAX]; int ret; ret = snprintf(file, sizeof(file), "/sys/kernel/debug/tracing/events/%s/%s/id", tp_category, tp_name); if (ret < 0) return -errno; if (ret >= sizeof(file)) { pr_debug("tracepoint %s/%s path is too long\n", tp_category, tp_name); return -E2BIG; } return parse_uint_from_file(file, "%d\n"); } static int perf_event_open_tracepoint(const char *tp_category, const char *tp_name) { struct perf_event_attr attr = {}; char errmsg[STRERR_BUFSIZE]; int tp_id, pfd, err; tp_id = determine_tracepoint_id(tp_category, tp_name); if (tp_id < 0) { pr_warn("failed to determine tracepoint '%s/%s' perf event ID: %s\n", tp_category, tp_name, libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg))); return tp_id; } attr.type = PERF_TYPE_TRACEPOINT; attr.size = sizeof(attr); attr.config = tp_id; pfd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */, -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC); if (pfd < 0) { err = -errno; pr_warn("tracepoint '%s/%s' perf_event_open() failed: %s\n", tp_category, tp_name, libbpf_strerror_r(err, errmsg, sizeof(errmsg))); return err; } return pfd; } struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog, const char *tp_category, const char *tp_name) { char errmsg[STRERR_BUFSIZE]; struct bpf_link *link; int pfd, err; pfd = perf_event_open_tracepoint(tp_category, tp_name); if (pfd < 0) { pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n", prog->name, tp_category, tp_name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg))); return ERR_PTR(pfd); } link = bpf_program__attach_perf_event(prog, pfd); if (IS_ERR(link)) { close(pfd); err = PTR_ERR(link); pr_warn("prog '%s': failed to attach to tracepoint '%s/%s': %s\n", prog->name, tp_category, tp_name, libbpf_strerror_r(err, errmsg, sizeof(errmsg))); return link; } return link; } static struct bpf_link *attach_tp(const struct bpf_sec_def *sec, struct bpf_program *prog) { char *sec_name, *tp_cat, *tp_name; struct bpf_link *link; sec_name = strdup(prog->sec_name); if (!sec_name) return ERR_PTR(-ENOMEM); /* extract "tp//" */ tp_cat = sec_name + sec->len; tp_name = strchr(tp_cat, '/'); if (!tp_name) { link = ERR_PTR(-EINVAL); goto out; } *tp_name = '\0'; tp_name++; link = bpf_program__attach_tracepoint(prog, tp_cat, tp_name); out: free(sec_name); return link; } struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog, const char *tp_name) { char errmsg[STRERR_BUFSIZE]; struct bpf_link *link; int prog_fd, pfd; prog_fd = bpf_program__fd(prog); if (prog_fd < 0) { pr_warn("prog '%s': can't attach before loaded\n", prog->name); return ERR_PTR(-EINVAL); } link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); link->detach = &bpf_link__detach_fd; pfd = bpf_raw_tracepoint_open(tp_name, prog_fd); if (pfd < 0) { pfd = -errno; free(link); pr_warn("prog '%s': failed to attach to raw tracepoint '%s': %s\n", prog->name, tp_name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg))); return ERR_PTR(pfd); } link->fd = pfd; return link; } static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec, struct bpf_program *prog) { const char *tp_name = prog->sec_name + sec->len; return bpf_program__attach_raw_tracepoint(prog, tp_name); } /* Common logic for all BPF program types that attach to a btf_id */ static struct bpf_link *bpf_program__attach_btf_id(struct bpf_program *prog) { char errmsg[STRERR_BUFSIZE]; struct bpf_link *link; int prog_fd, pfd; prog_fd = bpf_program__fd(prog); if (prog_fd < 0) { pr_warn("prog '%s': can't attach before loaded\n", prog->name); return ERR_PTR(-EINVAL); } link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); link->detach = &bpf_link__detach_fd; pfd = bpf_raw_tracepoint_open(NULL, prog_fd); if (pfd < 0) { pfd = -errno; free(link); pr_warn("prog '%s': failed to attach: %s\n", prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg))); return ERR_PTR(pfd); } link->fd = pfd; return (struct bpf_link *)link; } struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog) { return bpf_program__attach_btf_id(prog); } struct bpf_link *bpf_program__attach_lsm(struct bpf_program *prog) { return bpf_program__attach_btf_id(prog); } static struct bpf_link *attach_trace(const struct bpf_sec_def *sec, struct bpf_program *prog) { return bpf_program__attach_trace(prog); } static struct bpf_link *attach_lsm(const struct bpf_sec_def *sec, struct bpf_program *prog) { return bpf_program__attach_lsm(prog); } static struct bpf_link *attach_iter(const struct bpf_sec_def *sec, struct bpf_program *prog) { return bpf_program__attach_iter(prog, NULL); } static struct bpf_link * bpf_program__attach_fd(struct bpf_program *prog, int target_fd, int btf_id, const char *target_name) { DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts, .target_btf_id = btf_id); enum bpf_attach_type attach_type; char errmsg[STRERR_BUFSIZE]; struct bpf_link *link; int prog_fd, link_fd; prog_fd = bpf_program__fd(prog); if (prog_fd < 0) { pr_warn("prog '%s': can't attach before loaded\n", prog->name); return ERR_PTR(-EINVAL); } link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); link->detach = &bpf_link__detach_fd; attach_type = bpf_program__get_expected_attach_type(prog); link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts); if (link_fd < 0) { link_fd = -errno; free(link); pr_warn("prog '%s': failed to attach to %s: %s\n", prog->name, target_name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg))); return ERR_PTR(link_fd); } link->fd = link_fd; return link; } struct bpf_link * bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd) { return bpf_program__attach_fd(prog, cgroup_fd, 0, "cgroup"); } struct bpf_link * bpf_program__attach_netns(struct bpf_program *prog, int netns_fd) { return bpf_program__attach_fd(prog, netns_fd, 0, "netns"); } struct bpf_link *bpf_program__attach_xdp(struct bpf_program *prog, int ifindex) { /* target_fd/target_ifindex use the same field in LINK_CREATE */ return bpf_program__attach_fd(prog, ifindex, 0, "xdp"); } struct bpf_link *bpf_program__attach_freplace(struct bpf_program *prog, int target_fd, const char *attach_func_name) { int btf_id; if (!!target_fd != !!attach_func_name) { pr_warn("prog '%s': supply none or both of target_fd and attach_func_name\n", prog->name); return ERR_PTR(-EINVAL); } if (prog->type != BPF_PROG_TYPE_EXT) { pr_warn("prog '%s': only BPF_PROG_TYPE_EXT can attach as freplace", prog->name); return ERR_PTR(-EINVAL); } if (target_fd) { btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd); if (btf_id < 0) return ERR_PTR(btf_id); return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace"); } else { /* no target, so use raw_tracepoint_open for compatibility * with old kernels */ return bpf_program__attach_trace(prog); } } struct bpf_link * bpf_program__attach_iter(struct bpf_program *prog, const struct bpf_iter_attach_opts *opts) { DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_create_opts); char errmsg[STRERR_BUFSIZE]; struct bpf_link *link; int prog_fd, link_fd; __u32 target_fd = 0; if (!OPTS_VALID(opts, bpf_iter_attach_opts)) return ERR_PTR(-EINVAL); link_create_opts.iter_info = OPTS_GET(opts, link_info, (void *)0); link_create_opts.iter_info_len = OPTS_GET(opts, link_info_len, 0); prog_fd = bpf_program__fd(prog); if (prog_fd < 0) { pr_warn("prog '%s': can't attach before loaded\n", prog->name); return ERR_PTR(-EINVAL); } link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); link->detach = &bpf_link__detach_fd; link_fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_ITER, &link_create_opts); if (link_fd < 0) { link_fd = -errno; free(link); pr_warn("prog '%s': failed to attach to iterator: %s\n", prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg))); return ERR_PTR(link_fd); } link->fd = link_fd; return link; } struct bpf_link *bpf_program__attach(struct bpf_program *prog) { const struct bpf_sec_def *sec_def; sec_def = find_sec_def(prog->sec_name); if (!sec_def || !sec_def->attach_fn) return ERR_PTR(-ESRCH); return sec_def->attach_fn(sec_def, prog); } static int bpf_link__detach_struct_ops(struct bpf_link *link) { __u32 zero = 0; if (bpf_map_delete_elem(link->fd, &zero)) return -errno; return 0; } struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map) { struct bpf_struct_ops *st_ops; struct bpf_link *link; __u32 i, zero = 0; int err; if (!bpf_map__is_struct_ops(map) || map->fd == -1) return ERR_PTR(-EINVAL); link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-EINVAL); st_ops = map->st_ops; for (i = 0; i < btf_vlen(st_ops->type); i++) { struct bpf_program *prog = st_ops->progs[i]; void *kern_data; int prog_fd; if (!prog) continue; prog_fd = bpf_program__fd(prog); kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i]; *(unsigned long *)kern_data = prog_fd; } err = bpf_map_update_elem(map->fd, &zero, st_ops->kern_vdata, 0); if (err) { err = -errno; free(link); return ERR_PTR(err); } link->detach = bpf_link__detach_struct_ops; link->fd = map->fd; return link; } enum bpf_perf_event_ret bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size, void **copy_mem, size_t *copy_size, bpf_perf_event_print_t fn, void *private_data) { struct perf_event_mmap_page *header = mmap_mem; __u64 data_head = ring_buffer_read_head(header); __u64 data_tail = header->data_tail; void *base = ((__u8 *)header) + page_size; int ret = LIBBPF_PERF_EVENT_CONT; struct perf_event_header *ehdr; size_t ehdr_size; while (data_head != data_tail) { ehdr = base + (data_tail & (mmap_size - 1)); ehdr_size = ehdr->size; if (((void *)ehdr) + ehdr_size > base + mmap_size) { void *copy_start = ehdr; size_t len_first = base + mmap_size - copy_start; size_t len_secnd = ehdr_size - len_first; if (*copy_size < ehdr_size) { free(*copy_mem); *copy_mem = malloc(ehdr_size); if (!*copy_mem) { *copy_size = 0; ret = LIBBPF_PERF_EVENT_ERROR; break; } *copy_size = ehdr_size; } memcpy(*copy_mem, copy_start, len_first); memcpy(*copy_mem + len_first, base, len_secnd); ehdr = *copy_mem; } ret = fn(ehdr, private_data); data_tail += ehdr_size; if (ret != LIBBPF_PERF_EVENT_CONT) break; } ring_buffer_write_tail(header, data_tail); return ret; } struct perf_buffer; struct perf_buffer_params { struct perf_event_attr *attr; /* if event_cb is specified, it takes precendence */ perf_buffer_event_fn event_cb; /* sample_cb and lost_cb are higher-level common-case callbacks */ perf_buffer_sample_fn sample_cb; perf_buffer_lost_fn lost_cb; void *ctx; int cpu_cnt; int *cpus; int *map_keys; }; struct perf_cpu_buf { struct perf_buffer *pb; void *base; /* mmap()'ed memory */ void *buf; /* for reconstructing segmented data */ size_t buf_size; int fd; int cpu; int map_key; }; struct perf_buffer { perf_buffer_event_fn event_cb; perf_buffer_sample_fn sample_cb; perf_buffer_lost_fn lost_cb; void *ctx; /* passed into callbacks */ size_t page_size; size_t mmap_size; struct perf_cpu_buf **cpu_bufs; struct epoll_event *events; int cpu_cnt; /* number of allocated CPU buffers */ int epoll_fd; /* perf event FD */ int map_fd; /* BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map FD */ }; static void perf_buffer__free_cpu_buf(struct perf_buffer *pb, struct perf_cpu_buf *cpu_buf) { if (!cpu_buf) return; if (cpu_buf->base && munmap(cpu_buf->base, pb->mmap_size + pb->page_size)) pr_warn("failed to munmap cpu_buf #%d\n", cpu_buf->cpu); if (cpu_buf->fd >= 0) { ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0); close(cpu_buf->fd); } free(cpu_buf->buf); free(cpu_buf); } void perf_buffer__free(struct perf_buffer *pb) { int i; if (IS_ERR_OR_NULL(pb)) return; if (pb->cpu_bufs) { for (i = 0; i < pb->cpu_cnt; i++) { struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i]; if (!cpu_buf) continue; bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key); perf_buffer__free_cpu_buf(pb, cpu_buf); } free(pb->cpu_bufs); } if (pb->epoll_fd >= 0) close(pb->epoll_fd); free(pb->events); free(pb); } static struct perf_cpu_buf * perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr, int cpu, int map_key) { struct perf_cpu_buf *cpu_buf; char msg[STRERR_BUFSIZE]; int err; cpu_buf = calloc(1, sizeof(*cpu_buf)); if (!cpu_buf) return ERR_PTR(-ENOMEM); cpu_buf->pb = pb; cpu_buf->cpu = cpu; cpu_buf->map_key = map_key; cpu_buf->fd = syscall(__NR_perf_event_open, attr, -1 /* pid */, cpu, -1, PERF_FLAG_FD_CLOEXEC); if (cpu_buf->fd < 0) { err = -errno; pr_warn("failed to open perf buffer event on cpu #%d: %s\n", cpu, libbpf_strerror_r(err, msg, sizeof(msg))); goto error; } cpu_buf->base = mmap(NULL, pb->mmap_size + pb->page_size, PROT_READ | PROT_WRITE, MAP_SHARED, cpu_buf->fd, 0); if (cpu_buf->base == MAP_FAILED) { cpu_buf->base = NULL; err = -errno; pr_warn("failed to mmap perf buffer on cpu #%d: %s\n", cpu, libbpf_strerror_r(err, msg, sizeof(msg))); goto error; } if (ioctl(cpu_buf->fd, PERF_EVENT_IOC_ENABLE, 0) < 0) { err = -errno; pr_warn("failed to enable perf buffer event on cpu #%d: %s\n", cpu, libbpf_strerror_r(err, msg, sizeof(msg))); goto error; } return cpu_buf; error: perf_buffer__free_cpu_buf(pb, cpu_buf); return (struct perf_cpu_buf *)ERR_PTR(err); } static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt, struct perf_buffer_params *p); struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt, const struct perf_buffer_opts *opts) { struct perf_buffer_params p = {}; struct perf_event_attr attr = { 0, }; attr.config = PERF_COUNT_SW_BPF_OUTPUT; attr.type = PERF_TYPE_SOFTWARE; attr.sample_type = PERF_SAMPLE_RAW; attr.sample_period = 1; attr.wakeup_events = 1; p.attr = &attr; p.sample_cb = opts ? opts->sample_cb : NULL; p.lost_cb = opts ? opts->lost_cb : NULL; p.ctx = opts ? opts->ctx : NULL; return __perf_buffer__new(map_fd, page_cnt, &p); } struct perf_buffer * perf_buffer__new_raw(int map_fd, size_t page_cnt, const struct perf_buffer_raw_opts *opts) { struct perf_buffer_params p = {}; p.attr = opts->attr; p.event_cb = opts->event_cb; p.ctx = opts->ctx; p.cpu_cnt = opts->cpu_cnt; p.cpus = opts->cpus; p.map_keys = opts->map_keys; return __perf_buffer__new(map_fd, page_cnt, &p); } static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt, struct perf_buffer_params *p) { const char *online_cpus_file = "/sys/devices/system/cpu/online"; struct bpf_map_info map; char msg[STRERR_BUFSIZE]; struct perf_buffer *pb; bool *online = NULL; __u32 map_info_len; int err, i, j, n; if (page_cnt & (page_cnt - 1)) { pr_warn("page count should be power of two, but is %zu\n", page_cnt); return ERR_PTR(-EINVAL); } /* best-effort sanity checks */ memset(&map, 0, sizeof(map)); map_info_len = sizeof(map); err = bpf_obj_get_info_by_fd(map_fd, &map, &map_info_len); if (err) { err = -errno; /* if BPF_OBJ_GET_INFO_BY_FD is supported, will return * -EBADFD, -EFAULT, or -E2BIG on real error */ if (err != -EINVAL) { pr_warn("failed to get map info for map FD %d: %s\n", map_fd, libbpf_strerror_r(err, msg, sizeof(msg))); return ERR_PTR(err); } pr_debug("failed to get map info for FD %d; API not supported? Ignoring...\n", map_fd); } else { if (map.type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) { pr_warn("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n", map.name); return ERR_PTR(-EINVAL); } } pb = calloc(1, sizeof(*pb)); if (!pb) return ERR_PTR(-ENOMEM); pb->event_cb = p->event_cb; pb->sample_cb = p->sample_cb; pb->lost_cb = p->lost_cb; pb->ctx = p->ctx; pb->page_size = getpagesize(); pb->mmap_size = pb->page_size * page_cnt; pb->map_fd = map_fd; pb->epoll_fd = epoll_create1(EPOLL_CLOEXEC); if (pb->epoll_fd < 0) { err = -errno; pr_warn("failed to create epoll instance: %s\n", libbpf_strerror_r(err, msg, sizeof(msg))); goto error; } if (p->cpu_cnt > 0) { pb->cpu_cnt = p->cpu_cnt; } else { pb->cpu_cnt = libbpf_num_possible_cpus(); if (pb->cpu_cnt < 0) { err = pb->cpu_cnt; goto error; } if (map.max_entries && map.max_entries < pb->cpu_cnt) pb->cpu_cnt = map.max_entries; } pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events)); if (!pb->events) { err = -ENOMEM; pr_warn("failed to allocate events: out of memory\n"); goto error; } pb->cpu_bufs = calloc(pb->cpu_cnt, sizeof(*pb->cpu_bufs)); if (!pb->cpu_bufs) { err = -ENOMEM; pr_warn("failed to allocate buffers: out of memory\n"); goto error; } err = parse_cpu_mask_file(online_cpus_file, &online, &n); if (err) { pr_warn("failed to get online CPU mask: %d\n", err); goto error; } for (i = 0, j = 0; i < pb->cpu_cnt; i++) { struct perf_cpu_buf *cpu_buf; int cpu, map_key; cpu = p->cpu_cnt > 0 ? p->cpus[i] : i; map_key = p->cpu_cnt > 0 ? p->map_keys[i] : i; /* in case user didn't explicitly requested particular CPUs to * be attached to, skip offline/not present CPUs */ if (p->cpu_cnt <= 0 && (cpu >= n || !online[cpu])) continue; cpu_buf = perf_buffer__open_cpu_buf(pb, p->attr, cpu, map_key); if (IS_ERR(cpu_buf)) { err = PTR_ERR(cpu_buf); goto error; } pb->cpu_bufs[j] = cpu_buf; err = bpf_map_update_elem(pb->map_fd, &map_key, &cpu_buf->fd, 0); if (err) { err = -errno; pr_warn("failed to set cpu #%d, key %d -> perf FD %d: %s\n", cpu, map_key, cpu_buf->fd, libbpf_strerror_r(err, msg, sizeof(msg))); goto error; } pb->events[j].events = EPOLLIN; pb->events[j].data.ptr = cpu_buf; if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd, &pb->events[j]) < 0) { err = -errno; pr_warn("failed to epoll_ctl cpu #%d perf FD %d: %s\n", cpu, cpu_buf->fd, libbpf_strerror_r(err, msg, sizeof(msg))); goto error; } j++; } pb->cpu_cnt = j; free(online); return pb; error: free(online); if (pb) perf_buffer__free(pb); return ERR_PTR(err); } struct perf_sample_raw { struct perf_event_header header; uint32_t size; char data[]; }; struct perf_sample_lost { struct perf_event_header header; uint64_t id; uint64_t lost; uint64_t sample_id; }; static enum bpf_perf_event_ret perf_buffer__process_record(struct perf_event_header *e, void *ctx) { struct perf_cpu_buf *cpu_buf = ctx; struct perf_buffer *pb = cpu_buf->pb; void *data = e; /* user wants full control over parsing perf event */ if (pb->event_cb) return pb->event_cb(pb->ctx, cpu_buf->cpu, e); switch (e->type) { case PERF_RECORD_SAMPLE: { struct perf_sample_raw *s = data; if (pb->sample_cb) pb->sample_cb(pb->ctx, cpu_buf->cpu, s->data, s->size); break; } case PERF_RECORD_LOST: { struct perf_sample_lost *s = data; if (pb->lost_cb) pb->lost_cb(pb->ctx, cpu_buf->cpu, s->lost); break; } default: pr_warn("unknown perf sample type %d\n", e->type); return LIBBPF_PERF_EVENT_ERROR; } return LIBBPF_PERF_EVENT_CONT; } static int perf_buffer__process_records(struct perf_buffer *pb, struct perf_cpu_buf *cpu_buf) { enum bpf_perf_event_ret ret; ret = bpf_perf_event_read_simple(cpu_buf->base, pb->mmap_size, pb->page_size, &cpu_buf->buf, &cpu_buf->buf_size, perf_buffer__process_record, cpu_buf); if (ret != LIBBPF_PERF_EVENT_CONT) return ret; return 0; } int perf_buffer__epoll_fd(const struct perf_buffer *pb) { return pb->epoll_fd; } int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms) { int i, cnt, err; cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms); for (i = 0; i < cnt; i++) { struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr; err = perf_buffer__process_records(pb, cpu_buf); if (err) { pr_warn("error while processing records: %d\n", err); return err; } } return cnt < 0 ? -errno : cnt; } /* Return number of PERF_EVENT_ARRAY map slots set up by this perf_buffer * manager. */ size_t perf_buffer__buffer_cnt(const struct perf_buffer *pb) { return pb->cpu_cnt; } /* * Return perf_event FD of a ring buffer in *buf_idx* slot of * PERF_EVENT_ARRAY BPF map. This FD can be polled for new data using * select()/poll()/epoll() Linux syscalls. */ int perf_buffer__buffer_fd(const struct perf_buffer *pb, size_t buf_idx) { struct perf_cpu_buf *cpu_buf; if (buf_idx >= pb->cpu_cnt) return -EINVAL; cpu_buf = pb->cpu_bufs[buf_idx]; if (!cpu_buf) return -ENOENT; return cpu_buf->fd; } /* * Consume data from perf ring buffer corresponding to slot *buf_idx* in * PERF_EVENT_ARRAY BPF map without waiting/polling. If there is no data to * consume, do nothing and return success. * Returns: * - 0 on success; * - <0 on failure. */ int perf_buffer__consume_buffer(struct perf_buffer *pb, size_t buf_idx) { struct perf_cpu_buf *cpu_buf; if (buf_idx >= pb->cpu_cnt) return -EINVAL; cpu_buf = pb->cpu_bufs[buf_idx]; if (!cpu_buf) return -ENOENT; return perf_buffer__process_records(pb, cpu_buf); } int perf_buffer__consume(struct perf_buffer *pb) { int i, err; for (i = 0; i < pb->cpu_cnt; i++) { struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i]; if (!cpu_buf) continue; err = perf_buffer__process_records(pb, cpu_buf); if (err) { pr_warn("perf_buffer: failed to process records in buffer #%d: %d\n", i, err); return err; } } return 0; } struct bpf_prog_info_array_desc { int array_offset; /* e.g. offset of jited_prog_insns */ int count_offset; /* e.g. offset of jited_prog_len */ int size_offset; /* > 0: offset of rec size, * < 0: fix size of -size_offset */ }; static struct bpf_prog_info_array_desc bpf_prog_info_array_desc[] = { [BPF_PROG_INFO_JITED_INSNS] = { offsetof(struct bpf_prog_info, jited_prog_insns), offsetof(struct bpf_prog_info, jited_prog_len), -1, }, [BPF_PROG_INFO_XLATED_INSNS] = { offsetof(struct bpf_prog_info, xlated_prog_insns), offsetof(struct bpf_prog_info, xlated_prog_len), -1, }, [BPF_PROG_INFO_MAP_IDS] = { offsetof(struct bpf_prog_info, map_ids), offsetof(struct bpf_prog_info, nr_map_ids), -(int)sizeof(__u32), }, [BPF_PROG_INFO_JITED_KSYMS] = { offsetof(struct bpf_prog_info, jited_ksyms), offsetof(struct bpf_prog_info, nr_jited_ksyms), -(int)sizeof(__u64), }, [BPF_PROG_INFO_JITED_FUNC_LENS] = { offsetof(struct bpf_prog_info, jited_func_lens), offsetof(struct bpf_prog_info, nr_jited_func_lens), -(int)sizeof(__u32), }, [BPF_PROG_INFO_FUNC_INFO] = { offsetof(struct bpf_prog_info, func_info), offsetof(struct bpf_prog_info, nr_func_info), offsetof(struct bpf_prog_info, func_info_rec_size), }, [BPF_PROG_INFO_LINE_INFO] = { offsetof(struct bpf_prog_info, line_info), offsetof(struct bpf_prog_info, nr_line_info), offsetof(struct bpf_prog_info, line_info_rec_size), }, [BPF_PROG_INFO_JITED_LINE_INFO] = { offsetof(struct bpf_prog_info, jited_line_info), offsetof(struct bpf_prog_info, nr_jited_line_info), offsetof(struct bpf_prog_info, jited_line_info_rec_size), }, [BPF_PROG_INFO_PROG_TAGS] = { offsetof(struct bpf_prog_info, prog_tags), offsetof(struct bpf_prog_info, nr_prog_tags), -(int)sizeof(__u8) * BPF_TAG_SIZE, }, }; static __u32 bpf_prog_info_read_offset_u32(struct bpf_prog_info *info, int offset) { __u32 *array = (__u32 *)info; if (offset >= 0) return array[offset / sizeof(__u32)]; return -(int)offset; } static __u64 bpf_prog_info_read_offset_u64(struct bpf_prog_info *info, int offset) { __u64 *array = (__u64 *)info; if (offset >= 0) return array[offset / sizeof(__u64)]; return -(int)offset; } static void bpf_prog_info_set_offset_u32(struct bpf_prog_info *info, int offset, __u32 val) { __u32 *array = (__u32 *)info; if (offset >= 0) array[offset / sizeof(__u32)] = val; } static void bpf_prog_info_set_offset_u64(struct bpf_prog_info *info, int offset, __u64 val) { __u64 *array = (__u64 *)info; if (offset >= 0) array[offset / sizeof(__u64)] = val; } struct bpf_prog_info_linear * bpf_program__get_prog_info_linear(int fd, __u64 arrays) { struct bpf_prog_info_linear *info_linear; struct bpf_prog_info info = {}; __u32 info_len = sizeof(info); __u32 data_len = 0; int i, err; void *ptr; if (arrays >> BPF_PROG_INFO_LAST_ARRAY) return ERR_PTR(-EINVAL); /* step 1: get array dimensions */ err = bpf_obj_get_info_by_fd(fd, &info, &info_len); if (err) { pr_debug("can't get prog info: %s", strerror(errno)); return ERR_PTR(-EFAULT); } /* step 2: calculate total size of all arrays */ for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) { bool include_array = (arrays & (1UL << i)) > 0; struct bpf_prog_info_array_desc *desc; __u32 count, size; desc = bpf_prog_info_array_desc + i; /* kernel is too old to support this field */ if (info_len < desc->array_offset + sizeof(__u32) || info_len < desc->count_offset + sizeof(__u32) || (desc->size_offset > 0 && info_len < desc->size_offset)) include_array = false; if (!include_array) { arrays &= ~(1UL << i); /* clear the bit */ continue; } count = bpf_prog_info_read_offset_u32(&info, desc->count_offset); size = bpf_prog_info_read_offset_u32(&info, desc->size_offset); data_len += count * size; } /* step 3: allocate continuous memory */ data_len = roundup(data_len, sizeof(__u64)); info_linear = malloc(sizeof(struct bpf_prog_info_linear) + data_len); if (!info_linear) return ERR_PTR(-ENOMEM); /* step 4: fill data to info_linear->info */ info_linear->arrays = arrays; memset(&info_linear->info, 0, sizeof(info)); ptr = info_linear->data; for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) { struct bpf_prog_info_array_desc *desc; __u32 count, size; if ((arrays & (1UL << i)) == 0) continue; desc = bpf_prog_info_array_desc + i; count = bpf_prog_info_read_offset_u32(&info, desc->count_offset); size = bpf_prog_info_read_offset_u32(&info, desc->size_offset); bpf_prog_info_set_offset_u32(&info_linear->info, desc->count_offset, count); bpf_prog_info_set_offset_u32(&info_linear->info, desc->size_offset, size); bpf_prog_info_set_offset_u64(&info_linear->info, desc->array_offset, ptr_to_u64(ptr)); ptr += count * size; } /* step 5: call syscall again to get required arrays */ err = bpf_obj_get_info_by_fd(fd, &info_linear->info, &info_len); if (err) { pr_debug("can't get prog info: %s", strerror(errno)); free(info_linear); return ERR_PTR(-EFAULT); } /* step 6: verify the data */ for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) { struct bpf_prog_info_array_desc *desc; __u32 v1, v2; if ((arrays & (1UL << i)) == 0) continue; desc = bpf_prog_info_array_desc + i; v1 = bpf_prog_info_read_offset_u32(&info, desc->count_offset); v2 = bpf_prog_info_read_offset_u32(&info_linear->info, desc->count_offset); if (v1 != v2) pr_warn("%s: mismatch in element count\n", __func__); v1 = bpf_prog_info_read_offset_u32(&info, desc->size_offset); v2 = bpf_prog_info_read_offset_u32(&info_linear->info, desc->size_offset); if (v1 != v2) pr_warn("%s: mismatch in rec size\n", __func__); } /* step 7: update info_len and data_len */ info_linear->info_len = sizeof(struct bpf_prog_info); info_linear->data_len = data_len; return info_linear; } void bpf_program__bpil_addr_to_offs(struct bpf_prog_info_linear *info_linear) { int i; for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) { struct bpf_prog_info_array_desc *desc; __u64 addr, offs; if ((info_linear->arrays & (1UL << i)) == 0) continue; desc = bpf_prog_info_array_desc + i; addr = bpf_prog_info_read_offset_u64(&info_linear->info, desc->array_offset); offs = addr - ptr_to_u64(info_linear->data); bpf_prog_info_set_offset_u64(&info_linear->info, desc->array_offset, offs); } } void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear) { int i; for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) { struct bpf_prog_info_array_desc *desc; __u64 addr, offs; if ((info_linear->arrays & (1UL << i)) == 0) continue; desc = bpf_prog_info_array_desc + i; offs = bpf_prog_info_read_offset_u64(&info_linear->info, desc->array_offset); addr = offs + ptr_to_u64(info_linear->data); bpf_prog_info_set_offset_u64(&info_linear->info, desc->array_offset, addr); } } int bpf_program__set_attach_target(struct bpf_program *prog, int attach_prog_fd, const char *attach_func_name) { int btf_obj_fd = 0, btf_id = 0, err; if (!prog || attach_prog_fd < 0 || !attach_func_name) return -EINVAL; if (prog->obj->loaded) return -EINVAL; if (attach_prog_fd) { btf_id = libbpf_find_prog_btf_id(attach_func_name, attach_prog_fd); if (btf_id < 0) return btf_id; } else { /* load btf_vmlinux, if not yet */ err = bpf_object__load_vmlinux_btf(prog->obj, true); if (err) return err; err = find_kernel_btf_id(prog->obj, attach_func_name, prog->expected_attach_type, &btf_obj_fd, &btf_id); if (err) return err; } prog->attach_btf_id = btf_id; prog->attach_btf_obj_fd = btf_obj_fd; prog->attach_prog_fd = attach_prog_fd; return 0; } int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz) { int err = 0, n, len, start, end = -1; bool *tmp; *mask = NULL; *mask_sz = 0; /* Each sub string separated by ',' has format \d+-\d+ or \d+ */ while (*s) { if (*s == ',' || *s == '\n') { s++; continue; } n = sscanf(s, "%d%n-%d%n", &start, &len, &end, &len); if (n <= 0 || n > 2) { pr_warn("Failed to get CPU range %s: %d\n", s, n); err = -EINVAL; goto cleanup; } else if (n == 1) { end = start; } if (start < 0 || start > end) { pr_warn("Invalid CPU range [%d,%d] in %s\n", start, end, s); err = -EINVAL; goto cleanup; } tmp = realloc(*mask, end + 1); if (!tmp) { err = -ENOMEM; goto cleanup; } *mask = tmp; memset(tmp + *mask_sz, 0, start - *mask_sz); memset(tmp + start, 1, end - start + 1); *mask_sz = end + 1; s += len; } if (!*mask_sz) { pr_warn("Empty CPU range\n"); return -EINVAL; } return 0; cleanup: free(*mask); *mask = NULL; return err; } int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz) { int fd, err = 0, len; char buf[128]; fd = open(fcpu, O_RDONLY); if (fd < 0) { err = -errno; pr_warn("Failed to open cpu mask file %s: %d\n", fcpu, err); return err; } len = read(fd, buf, sizeof(buf)); close(fd); if (len <= 0) { err = len ? -errno : -EINVAL; pr_warn("Failed to read cpu mask from %s: %d\n", fcpu, err); return err; } if (len >= sizeof(buf)) { pr_warn("CPU mask is too big in file %s\n", fcpu); return -E2BIG; } buf[len] = '\0'; return parse_cpu_mask_str(buf, mask, mask_sz); } int libbpf_num_possible_cpus(void) { static const char *fcpu = "/sys/devices/system/cpu/possible"; static int cpus; int err, n, i, tmp_cpus; bool *mask; tmp_cpus = READ_ONCE(cpus); if (tmp_cpus > 0) return tmp_cpus; err = parse_cpu_mask_file(fcpu, &mask, &n); if (err) return err; tmp_cpus = 0; for (i = 0; i < n; i++) { if (mask[i]) tmp_cpus++; } free(mask); WRITE_ONCE(cpus, tmp_cpus); return tmp_cpus; } int bpf_object__open_skeleton(struct bpf_object_skeleton *s, const struct bpf_object_open_opts *opts) { DECLARE_LIBBPF_OPTS(bpf_object_open_opts, skel_opts, .object_name = s->name, ); struct bpf_object *obj; int i; /* Attempt to preserve opts->object_name, unless overriden by user * explicitly. Overwriting object name for skeletons is discouraged, * as it breaks global data maps, because they contain object name * prefix as their own map name prefix. When skeleton is generated, * bpftool is making an assumption that this name will stay the same. */ if (opts) { memcpy(&skel_opts, opts, sizeof(*opts)); if (!opts->object_name) skel_opts.object_name = s->name; } obj = bpf_object__open_mem(s->data, s->data_sz, &skel_opts); if (IS_ERR(obj)) { pr_warn("failed to initialize skeleton BPF object '%s': %ld\n", s->name, PTR_ERR(obj)); return PTR_ERR(obj); } *s->obj = obj; for (i = 0; i < s->map_cnt; i++) { struct bpf_map **map = s->maps[i].map; const char *name = s->maps[i].name; void **mmaped = s->maps[i].mmaped; *map = bpf_object__find_map_by_name(obj, name); if (!*map) { pr_warn("failed to find skeleton map '%s'\n", name); return -ESRCH; } /* externs shouldn't be pre-setup from user code */ if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_KCONFIG) *mmaped = (*map)->mmaped; } for (i = 0; i < s->prog_cnt; i++) { struct bpf_program **prog = s->progs[i].prog; const char *name = s->progs[i].name; *prog = bpf_object__find_program_by_name(obj, name); if (!*prog) { pr_warn("failed to find skeleton program '%s'\n", name); return -ESRCH; } } return 0; } int bpf_object__load_skeleton(struct bpf_object_skeleton *s) { int i, err; err = bpf_object__load(*s->obj); if (err) { pr_warn("failed to load BPF skeleton '%s': %d\n", s->name, err); return err; } for (i = 0; i < s->map_cnt; i++) { struct bpf_map *map = *s->maps[i].map; size_t mmap_sz = bpf_map_mmap_sz(map); int prot, map_fd = bpf_map__fd(map); void **mmaped = s->maps[i].mmaped; if (!mmaped) continue; if (!(map->def.map_flags & BPF_F_MMAPABLE)) { *mmaped = NULL; continue; } if (map->def.map_flags & BPF_F_RDONLY_PROG) prot = PROT_READ; else prot = PROT_READ | PROT_WRITE; /* Remap anonymous mmap()-ed "map initialization image" as * a BPF map-backed mmap()-ed memory, but preserving the same * memory address. This will cause kernel to change process' * page table to point to a different piece of kernel memory, * but from userspace point of view memory address (and its * contents, being identical at this point) will stay the * same. This mapping will be released by bpf_object__close() * as per normal clean up procedure, so we don't need to worry * about it from skeleton's clean up perspective. */ *mmaped = mmap(map->mmaped, mmap_sz, prot, MAP_SHARED | MAP_FIXED, map_fd, 0); if (*mmaped == MAP_FAILED) { err = -errno; *mmaped = NULL; pr_warn("failed to re-mmap() map '%s': %d\n", bpf_map__name(map), err); return err; } } return 0; } int bpf_object__attach_skeleton(struct bpf_object_skeleton *s) { int i; for (i = 0; i < s->prog_cnt; i++) { struct bpf_program *prog = *s->progs[i].prog; struct bpf_link **link = s->progs[i].link; const struct bpf_sec_def *sec_def; if (!prog->load) continue; sec_def = find_sec_def(prog->sec_name); if (!sec_def || !sec_def->attach_fn) continue; *link = sec_def->attach_fn(sec_def, prog); if (IS_ERR(*link)) { pr_warn("failed to auto-attach program '%s': %ld\n", bpf_program__name(prog), PTR_ERR(*link)); return PTR_ERR(*link); } } return 0; } void bpf_object__detach_skeleton(struct bpf_object_skeleton *s) { int i; for (i = 0; i < s->prog_cnt; i++) { struct bpf_link **link = s->progs[i].link; bpf_link__destroy(*link); *link = NULL; } } void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s) { if (s->progs) bpf_object__detach_skeleton(s); if (s->obj) bpf_object__close(*s->obj); free(s->maps); free(s->progs); free(s); }