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Diffstat (limited to 'tools/lib/bpf/libbpf.c')
-rw-r--r--tools/lib/bpf/libbpf.c332
1 files changed, 329 insertions, 3 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 809fe209cdcc..6d2be53e4ba9 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8630,6 +8630,7 @@ int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log
}
static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link);
@@ -8642,9 +8643,9 @@ static const struct bpf_sec_def section_defs[] = {
SEC_DEF("sk_reuseport/migrate", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, SEC_ATTACHABLE | SEC_SLOPPY_PFX),
SEC_DEF("sk_reuseport", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT, SEC_ATTACHABLE | SEC_SLOPPY_PFX),
SEC_DEF("kprobe/", KPROBE, 0, SEC_NONE, attach_kprobe),
- SEC_DEF("uprobe/", KPROBE, 0, SEC_NONE),
+ SEC_DEF("uprobe+", KPROBE, 0, SEC_NONE, attach_uprobe),
SEC_DEF("kretprobe/", KPROBE, 0, SEC_NONE, attach_kprobe),
- SEC_DEF("uretprobe/", KPROBE, 0, SEC_NONE),
+ SEC_DEF("uretprobe+", KPROBE, 0, SEC_NONE, attach_uprobe),
SEC_DEF("kprobe.multi/", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
SEC_DEF("kretprobe.multi/", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
SEC_DEF("tc", SCHED_CLS, 0, SEC_NONE),
@@ -10517,6 +10518,235 @@ static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
return pfd;
}
+/* uprobes deal in relative offsets; subtract the base address associated with
+ * the mapped binary. See Documentation/trace/uprobetracer.rst for more
+ * details.
+ */
+static long elf_find_relative_offset(const char *filename, Elf *elf, long addr)
+{
+ size_t n;
+ int i;
+
+ if (elf_getphdrnum(elf, &n)) {
+ pr_warn("elf: failed to find program headers for '%s': %s\n", filename,
+ elf_errmsg(-1));
+ return -ENOENT;
+ }
+
+ for (i = 0; i < n; i++) {
+ int seg_start, seg_end, seg_offset;
+ GElf_Phdr phdr;
+
+ if (!gelf_getphdr(elf, i, &phdr)) {
+ pr_warn("elf: failed to get program header %d from '%s': %s\n", i, filename,
+ elf_errmsg(-1));
+ return -ENOENT;
+ }
+ if (phdr.p_type != PT_LOAD || !(phdr.p_flags & PF_X))
+ continue;
+
+ seg_start = phdr.p_vaddr;
+ seg_end = seg_start + phdr.p_memsz;
+ seg_offset = phdr.p_offset;
+ if (addr >= seg_start && addr < seg_end)
+ return addr - seg_start + seg_offset;
+ }
+ pr_warn("elf: failed to find prog header containing 0x%lx in '%s'\n", addr, filename);
+ return -ENOENT;
+}
+
+/* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */
+static Elf_Scn *elf_find_next_scn_by_type(Elf *elf, int sh_type, Elf_Scn *scn)
+{
+ while ((scn = elf_nextscn(elf, scn)) != NULL) {
+ GElf_Shdr sh;
+
+ if (!gelf_getshdr(scn, &sh))
+ continue;
+ if (sh.sh_type == sh_type)
+ return scn;
+ }
+ return NULL;
+}
+
+/* Find offset of function name in object specified by path. "name" matches
+ * symbol name or name@@LIB for library functions.
+ */
+static long elf_find_func_offset(const char *binary_path, const char *name)
+{
+ int fd, i, sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
+ bool is_shared_lib, is_name_qualified;
+ char errmsg[STRERR_BUFSIZE];
+ long ret = -ENOENT;
+ size_t name_len;
+ GElf_Ehdr ehdr;
+ Elf *elf;
+
+ fd = open(binary_path, O_RDONLY | O_CLOEXEC);
+ if (fd < 0) {
+ ret = -errno;
+ pr_warn("failed to open %s: %s\n", binary_path,
+ libbpf_strerror_r(ret, errmsg, sizeof(errmsg)));
+ return ret;
+ }
+ elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ if (!elf) {
+ pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1));
+ close(fd);
+ return -LIBBPF_ERRNO__FORMAT;
+ }
+ if (!gelf_getehdr(elf, &ehdr)) {
+ pr_warn("elf: failed to get ehdr from %s: %s\n", binary_path, elf_errmsg(-1));
+ ret = -LIBBPF_ERRNO__FORMAT;
+ goto out;
+ }
+ /* for shared lib case, we do not need to calculate relative offset */
+ is_shared_lib = ehdr.e_type == ET_DYN;
+
+ name_len = strlen(name);
+ /* Does name specify "@@LIB"? */
+ is_name_qualified = strstr(name, "@@") != NULL;
+
+ /* Search SHT_DYNSYM, SHT_SYMTAB for symbol. This search order is used because if
+ * a binary is stripped, it may only have SHT_DYNSYM, and a fully-statically
+ * linked binary may not have SHT_DYMSYM, so absence of a section should not be
+ * reported as a warning/error.
+ */
+ for (i = 0; i < ARRAY_SIZE(sh_types); i++) {
+ size_t nr_syms, strtabidx, idx;
+ Elf_Data *symbols = NULL;
+ Elf_Scn *scn = NULL;
+ int last_bind = -1;
+ const char *sname;
+ GElf_Shdr sh;
+
+ scn = elf_find_next_scn_by_type(elf, sh_types[i], NULL);
+ if (!scn) {
+ pr_debug("elf: failed to find symbol table ELF sections in '%s'\n",
+ binary_path);
+ continue;
+ }
+ if (!gelf_getshdr(scn, &sh))
+ continue;
+ strtabidx = sh.sh_link;
+ symbols = elf_getdata(scn, 0);
+ if (!symbols) {
+ pr_warn("elf: failed to get symbols for symtab section in '%s': %s\n",
+ binary_path, elf_errmsg(-1));
+ ret = -LIBBPF_ERRNO__FORMAT;
+ goto out;
+ }
+ nr_syms = symbols->d_size / sh.sh_entsize;
+
+ for (idx = 0; idx < nr_syms; idx++) {
+ int curr_bind;
+ GElf_Sym sym;
+
+ if (!gelf_getsym(symbols, idx, &sym))
+ continue;
+
+ if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
+ continue;
+
+ sname = elf_strptr(elf, strtabidx, sym.st_name);
+ if (!sname)
+ continue;
+
+ curr_bind = GELF_ST_BIND(sym.st_info);
+
+ /* User can specify func, func@@LIB or func@@LIB_VERSION. */
+ if (strncmp(sname, name, name_len) != 0)
+ continue;
+ /* ...but we don't want a search for "foo" to match 'foo2" also, so any
+ * additional characters in sname should be of the form "@@LIB".
+ */
+ if (!is_name_qualified && sname[name_len] != '\0' && sname[name_len] != '@')
+ continue;
+
+ if (ret >= 0) {
+ /* handle multiple matches */
+ if (last_bind != STB_WEAK && curr_bind != STB_WEAK) {
+ /* Only accept one non-weak bind. */
+ pr_warn("elf: ambiguous match for '%s', '%s' in '%s'\n",
+ sname, name, binary_path);
+ ret = -LIBBPF_ERRNO__FORMAT;
+ goto out;
+ } else if (curr_bind == STB_WEAK) {
+ /* already have a non-weak bind, and
+ * this is a weak bind, so ignore.
+ */
+ continue;
+ }
+ }
+ ret = sym.st_value;
+ last_bind = curr_bind;
+ }
+ /* For binaries that are not shared libraries, we need relative offset */
+ if (ret > 0 && !is_shared_lib)
+ ret = elf_find_relative_offset(binary_path, elf, ret);
+ if (ret > 0)
+ break;
+ }
+
+ if (ret > 0) {
+ pr_debug("elf: symbol address match for '%s' in '%s': 0x%lx\n", name, binary_path,
+ ret);
+ } else {
+ if (ret == 0) {
+ pr_warn("elf: '%s' is 0 in symtab for '%s': %s\n", name, binary_path,
+ is_shared_lib ? "should not be 0 in a shared library" :
+ "try using shared library path instead");
+ ret = -ENOENT;
+ } else {
+ pr_warn("elf: failed to find symbol '%s' in '%s'\n", name, binary_path);
+ }
+ }
+out:
+ elf_end(elf);
+ close(fd);
+ return ret;
+}
+
+/* Get full path to program/shared library. */
+static int resolve_full_path(const char *file, char *result, size_t result_sz)
+{
+ const char *search_paths[2];
+ int i;
+
+ if (strstr(file, ".so")) {
+ search_paths[0] = getenv("LD_LIBRARY_PATH");
+ search_paths[1] = "/usr/lib64:/usr/lib";
+ } else {
+ search_paths[0] = getenv("PATH");
+ search_paths[1] = "/usr/bin:/usr/sbin";
+ }
+
+ for (i = 0; i < ARRAY_SIZE(search_paths); i++) {
+ const char *s;
+
+ if (!search_paths[i])
+ continue;
+ for (s = search_paths[i]; s != NULL; s = strchr(s, ':')) {
+ char *next_path;
+ int seg_len;
+
+ if (s[0] == ':')
+ s++;
+ next_path = strchr(s, ':');
+ seg_len = next_path ? next_path - s : strlen(s);
+ if (!seg_len)
+ continue;
+ snprintf(result, result_sz, "%.*s/%s", seg_len, s, file);
+ /* ensure it is an executable file/link */
+ if (access(result, R_OK | X_OK) < 0)
+ continue;
+ pr_debug("resolved '%s' to '%s'\n", file, result);
+ return 0;
+ }
+ }
+ return -ENOENT;
+}
+
LIBBPF_API struct bpf_link *
bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
const char *binary_path, size_t func_offset,
@@ -10524,10 +10754,12 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
{
DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE], *legacy_probe = NULL;
+ char full_binary_path[PATH_MAX];
struct bpf_link *link;
size_t ref_ctr_off;
int pfd, err;
bool retprobe, legacy;
+ const char *func_name;
if (!OPTS_VALID(opts, bpf_uprobe_opts))
return libbpf_err_ptr(-EINVAL);
@@ -10536,12 +10768,37 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
ref_ctr_off = OPTS_GET(opts, ref_ctr_offset, 0);
pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+ if (binary_path && !strchr(binary_path, '/')) {
+ err = resolve_full_path(binary_path, full_binary_path,
+ sizeof(full_binary_path));
+ if (err) {
+ pr_warn("prog '%s': failed to resolve full path for '%s'\n",
+ prog->name, binary_path);
+ return libbpf_err_ptr(err);
+ }
+ binary_path = full_binary_path;
+ }
+ func_name = OPTS_GET(opts, func_name, NULL);
+ if (func_name) {
+ long sym_off;
+
+ if (!binary_path) {
+ pr_warn("prog '%s': name-based attach requires binary_path\n",
+ prog->name);
+ return libbpf_err_ptr(-EINVAL);
+ }
+ sym_off = elf_find_func_offset(binary_path, func_name);
+ if (sym_off < 0)
+ return libbpf_err_ptr(sym_off);
+ func_offset += sym_off;
+ }
+
legacy = determine_uprobe_perf_type() < 0;
if (!legacy) {
pfd = perf_event_open_probe(true /* uprobe */, retprobe, binary_path,
func_offset, pid, ref_ctr_off);
} else {
- char probe_name[512];
+ char probe_name[PATH_MAX + 64];
if (ref_ctr_off)
return libbpf_err_ptr(-EINVAL);
@@ -10589,6 +10846,75 @@ err_out:
}
+/* Format of u[ret]probe section definition supporting auto-attach:
+ * u[ret]probe/binary:function[+offset]
+ *
+ * binary can be an absolute/relative path or a filename; the latter is resolved to a
+ * full binary path via bpf_program__attach_uprobe_opts.
+ *
+ * Specifying uprobe+ ensures we carry out strict matching; either "uprobe" must be
+ * specified (and auto-attach is not possible) or the above format is specified for
+ * auto-attach.
+ */
+static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+ DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts);
+ char *func, *probe_name, *func_end;
+ char *func_name, binary_path[512];
+ unsigned long long raw_offset;
+ size_t offset = 0;
+ int n;
+
+ *link = NULL;
+
+ opts.retprobe = str_has_pfx(prog->sec_name, "uretprobe");
+ if (opts.retprobe)
+ probe_name = prog->sec_name + sizeof("uretprobe") - 1;
+ else
+ probe_name = prog->sec_name + sizeof("uprobe") - 1;
+ if (probe_name[0] == '/')
+ probe_name++;
+
+ /* handle SEC("u[ret]probe") - format is valid, but auto-attach is impossible. */
+ if (strlen(probe_name) == 0)
+ return 0;
+
+ snprintf(binary_path, sizeof(binary_path), "%s", probe_name);
+ /* ':' should be prior to function+offset */
+ func_name = strrchr(binary_path, ':');
+ if (!func_name) {
+ pr_warn("section '%s' missing ':function[+offset]' specification\n",
+ prog->sec_name);
+ return -EINVAL;
+ }
+ func_name[0] = '\0';
+ func_name++;
+ n = sscanf(func_name, "%m[a-zA-Z0-9_.]+%li", &func, &offset);
+ if (n < 1) {
+ pr_warn("uprobe name '%s' is invalid\n", func_name);
+ return -EINVAL;
+ }
+ if (opts.retprobe && offset != 0) {
+ free(func);
+ pr_warn("uretprobes do not support offset specification\n");
+ return -EINVAL;
+ }
+
+ /* Is func a raw address? */
+ errno = 0;
+ raw_offset = strtoull(func, &func_end, 0);
+ if (!errno && !*func_end) {
+ free(func);
+ func = NULL;
+ offset = (size_t)raw_offset;
+ }
+ opts.func_name = func;
+
+ *link = bpf_program__attach_uprobe_opts(prog, -1, binary_path, offset, &opts);
+ free(func);
+ return libbpf_get_error(*link);
+}
+
struct bpf_link *bpf_program__attach_uprobe(const struct bpf_program *prog,
bool retprobe, pid_t pid,
const char *binary_path,
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-06 04:23:15 +0300