diff options
Diffstat (limited to 'tools/lib/bpf/libbpf_probes.c')
-rw-r--r-- | tools/lib/bpf/libbpf_probes.c | 235 |
1 files changed, 185 insertions, 50 deletions
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c index 4bdec69523a7..9d3985283dfc 100644 --- a/tools/lib/bpf/libbpf_probes.c +++ b/tools/lib/bpf/libbpf_probes.c @@ -64,12 +64,20 @@ static int get_kernel_version(void) return (version << 16) + (subversion << 8) + patchlevel; } -static void -probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, - size_t insns_cnt, char *buf, size_t buf_len, __u32 ifindex) +static int probe_prog_load(enum bpf_prog_type prog_type, + const struct bpf_insn *insns, size_t insns_cnt, + char *log_buf, size_t log_buf_sz, + __u32 ifindex) { - LIBBPF_OPTS(bpf_prog_load_opts, opts); - int fd; + LIBBPF_OPTS(bpf_prog_load_opts, opts, + .log_buf = log_buf, + .log_size = log_buf_sz, + .log_level = log_buf ? 1 : 0, + .prog_ifindex = ifindex, + ); + int fd, err, exp_err = 0; + const char *exp_msg = NULL; + char buf[4096]; switch (prog_type) { case BPF_PROG_TYPE_CGROUP_SOCK_ADDR: @@ -84,6 +92,38 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, case BPF_PROG_TYPE_KPROBE: opts.kern_version = get_kernel_version(); break; + case BPF_PROG_TYPE_LIRC_MODE2: + opts.expected_attach_type = BPF_LIRC_MODE2; + break; + case BPF_PROG_TYPE_TRACING: + case BPF_PROG_TYPE_LSM: + opts.log_buf = buf; + opts.log_size = sizeof(buf); + opts.log_level = 1; + if (prog_type == BPF_PROG_TYPE_TRACING) + opts.expected_attach_type = BPF_TRACE_FENTRY; + else + opts.expected_attach_type = BPF_MODIFY_RETURN; + opts.attach_btf_id = 1; + + exp_err = -EINVAL; + exp_msg = "attach_btf_id 1 is not a function"; + break; + case BPF_PROG_TYPE_EXT: + opts.log_buf = buf; + opts.log_size = sizeof(buf); + opts.log_level = 1; + opts.attach_btf_id = 1; + + exp_err = -EINVAL; + exp_msg = "Cannot replace kernel functions"; + break; + case BPF_PROG_TYPE_SYSCALL: + opts.prog_flags = BPF_F_SLEEPABLE; + break; + case BPF_PROG_TYPE_STRUCT_OPS: + exp_err = -524; /* -ENOTSUPP */ + break; case BPF_PROG_TYPE_UNSPEC: case BPF_PROG_TYPE_SOCKET_FILTER: case BPF_PROG_TYPE_SCHED_CLS: @@ -103,25 +143,42 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, case BPF_PROG_TYPE_RAW_TRACEPOINT: case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE: case BPF_PROG_TYPE_LWT_SEG6LOCAL: - case BPF_PROG_TYPE_LIRC_MODE2: case BPF_PROG_TYPE_SK_REUSEPORT: case BPF_PROG_TYPE_FLOW_DISSECTOR: case BPF_PROG_TYPE_CGROUP_SYSCTL: - case BPF_PROG_TYPE_TRACING: - case BPF_PROG_TYPE_STRUCT_OPS: - case BPF_PROG_TYPE_EXT: - case BPF_PROG_TYPE_LSM: - default: break; + default: + return -EOPNOTSUPP; } - opts.prog_ifindex = ifindex; - opts.log_buf = buf; - opts.log_size = buf_len; - - fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, NULL); + fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts); + err = -errno; if (fd >= 0) close(fd); + if (exp_err) { + if (fd >= 0 || err != exp_err) + return 0; + if (exp_msg && !strstr(buf, exp_msg)) + return 0; + return 1; + } + return fd >= 0 ? 1 : 0; +} + +int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts) +{ + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN() + }; + const size_t insn_cnt = ARRAY_SIZE(insns); + int ret; + + if (opts) + return libbpf_err(-EINVAL); + + ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0, 0); + return libbpf_err(ret); } bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex) @@ -131,12 +188,16 @@ bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex) BPF_EXIT_INSN() }; + /* prefer libbpf_probe_bpf_prog_type() unless offload is requested */ + if (ifindex == 0) + return libbpf_probe_bpf_prog_type(prog_type, NULL) == 1; + if (ifindex && prog_type == BPF_PROG_TYPE_SCHED_CLS) /* nfp returns -EINVAL on exit(0) with TC offload */ insns[0].imm = 2; errno = 0; - probe_load(prog_type, insns, ARRAY_SIZE(insns), NULL, 0, ifindex); + probe_prog_load(prog_type, insns, ARRAY_SIZE(insns), NULL, 0, ifindex); return errno != EINVAL && errno != EOPNOTSUPP; } @@ -197,16 +258,18 @@ static int load_local_storage_btf(void) strs, sizeof(strs)); } -bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex) +static int probe_map_create(enum bpf_map_type map_type, __u32 ifindex) { - int key_size, value_size, max_entries, map_flags; + LIBBPF_OPTS(bpf_map_create_opts, opts); + int key_size, value_size, max_entries; __u32 btf_key_type_id = 0, btf_value_type_id = 0; - int fd = -1, btf_fd = -1, fd_inner; + int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err; + + opts.map_ifindex = ifindex; key_size = sizeof(__u32); value_size = sizeof(__u32); max_entries = 1; - map_flags = 0; switch (map_type) { case BPF_MAP_TYPE_STACK_TRACE: @@ -215,7 +278,7 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex) case BPF_MAP_TYPE_LPM_TRIE: key_size = sizeof(__u64); value_size = sizeof(__u64); - map_flags = BPF_F_NO_PREALLOC; + opts.map_flags = BPF_F_NO_PREALLOC; break; case BPF_MAP_TYPE_CGROUP_STORAGE: case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE: @@ -234,17 +297,25 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex) btf_value_type_id = 3; value_size = 8; max_entries = 0; - map_flags = BPF_F_NO_PREALLOC; + opts.map_flags = BPF_F_NO_PREALLOC; btf_fd = load_local_storage_btf(); if (btf_fd < 0) - return false; + return btf_fd; break; case BPF_MAP_TYPE_RINGBUF: key_size = 0; value_size = 0; max_entries = 4096; break; - case BPF_MAP_TYPE_UNSPEC: + case BPF_MAP_TYPE_STRUCT_OPS: + /* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */ + opts.btf_vmlinux_value_type_id = 1; + exp_err = -524; /* -ENOTSUPP */ + break; + case BPF_MAP_TYPE_BLOOM_FILTER: + key_size = 0; + max_entries = 1; + break; case BPF_MAP_TYPE_HASH: case BPF_MAP_TYPE_ARRAY: case BPF_MAP_TYPE_PROG_ARRAY: @@ -263,49 +334,114 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex) case BPF_MAP_TYPE_XSKMAP: case BPF_MAP_TYPE_SOCKHASH: case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY: - case BPF_MAP_TYPE_STRUCT_OPS: - default: break; + case BPF_MAP_TYPE_UNSPEC: + default: + return -EOPNOTSUPP; } if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS || map_type == BPF_MAP_TYPE_HASH_OF_MAPS) { - LIBBPF_OPTS(bpf_map_create_opts, opts); - /* TODO: probe for device, once libbpf has a function to create * map-in-map for offload */ if (ifindex) - return false; + goto cleanup; fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL, sizeof(__u32), sizeof(__u32), 1, NULL); if (fd_inner < 0) - return false; + goto cleanup; opts.inner_map_fd = fd_inner; - fd = bpf_map_create(map_type, NULL, sizeof(__u32), sizeof(__u32), 1, &opts); - close(fd_inner); - } else { - LIBBPF_OPTS(bpf_map_create_opts, opts); - - /* Note: No other restriction on map type probes for offload */ - opts.map_flags = map_flags; - opts.map_ifindex = ifindex; - if (btf_fd >= 0) { - opts.btf_fd = btf_fd; - opts.btf_key_type_id = btf_key_type_id; - opts.btf_value_type_id = btf_value_type_id; - } + } - fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts); + if (btf_fd >= 0) { + opts.btf_fd = btf_fd; + opts.btf_key_type_id = btf_key_type_id; + opts.btf_value_type_id = btf_value_type_id; } + + fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts); + err = -errno; + +cleanup: if (fd >= 0) close(fd); + if (fd_inner >= 0) + close(fd_inner); if (btf_fd >= 0) close(btf_fd); - return fd >= 0; + if (exp_err) + return fd < 0 && err == exp_err ? 1 : 0; + else + return fd >= 0 ? 1 : 0; +} + +int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts) +{ + int ret; + + if (opts) + return libbpf_err(-EINVAL); + + ret = probe_map_create(map_type, 0); + return libbpf_err(ret); +} + +bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex) +{ + return probe_map_create(map_type, ifindex) == 1; +} + +int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id, + const void *opts) +{ + struct bpf_insn insns[] = { + BPF_EMIT_CALL((__u32)helper_id), + BPF_EXIT_INSN(), + }; + const size_t insn_cnt = ARRAY_SIZE(insns); + char buf[4096]; + int ret; + + if (opts) + return libbpf_err(-EINVAL); + + /* we can't successfully load all prog types to check for BPF helper + * support, so bail out with -EOPNOTSUPP error + */ + switch (prog_type) { + case BPF_PROG_TYPE_TRACING: + case BPF_PROG_TYPE_EXT: + case BPF_PROG_TYPE_LSM: + case BPF_PROG_TYPE_STRUCT_OPS: + return -EOPNOTSUPP; + default: + break; + } + + buf[0] = '\0'; + ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf), 0); + if (ret < 0) + return libbpf_err(ret); + + /* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id) + * at all, it will emit something like "invalid func unknown#181". + * If BPF verifier recognizes BPF helper but it's not supported for + * given BPF program type, it will emit "unknown func bpf_sys_bpf#166". + * In both cases, provided combination of BPF program type and BPF + * helper is not supported by the kernel. + * In all other cases, probe_prog_load() above will either succeed (e.g., + * because BPF helper happens to accept no input arguments or it + * accepts one input argument and initial PTR_TO_CTX is fine for + * that), or we'll get some more specific BPF verifier error about + * some unsatisfied conditions. + */ + if (ret == 0 && (strstr(buf, "invalid func ") || strstr(buf, "unknown func "))) + return 0; + return 1; /* assume supported */ } bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type, @@ -318,8 +454,7 @@ bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type, char buf[4096] = {}; bool res; - probe_load(prog_type, insns, ARRAY_SIZE(insns), buf, sizeof(buf), - ifindex); + probe_prog_load(prog_type, insns, ARRAY_SIZE(insns), buf, sizeof(buf), ifindex); res = !grep(buf, "invalid func ") && !grep(buf, "unknown func "); if (ifindex) { @@ -351,8 +486,8 @@ bool bpf_probe_large_insn_limit(__u32 ifindex) insns[BPF_MAXINSNS] = BPF_EXIT_INSN(); errno = 0; - probe_load(BPF_PROG_TYPE_SCHED_CLS, insns, ARRAY_SIZE(insns), NULL, 0, - ifindex); + probe_prog_load(BPF_PROG_TYPE_SCHED_CLS, insns, ARRAY_SIZE(insns), NULL, 0, + ifindex); return errno != E2BIG && errno != EINVAL; } |