diff options
| author | Alan Maguire <alan.maguire@oracle.com> | 2022-03-30 16:26:38 +0100 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2022-04-03 19:55:57 -0700 |
| commit | 39f8dc43b7a05ab0e352655a14a9d613c2308b92 (patch) | |
| tree | 32ebf3438890623070e52d37c9cff2944ef2cb1b /tools/lib | |
| parent | 433966e3ae04165811b116af492a684bad7a158c (diff) | |
libbpf: Add auto-attach for uprobes based on section name
Now that u[ret]probes can use name-based specification, it makes
sense to add support for auto-attach based on SEC() definition.
The format proposed is
SEC("u[ret]probe/binary:[raw_offset|[function_name[+offset]]")
For example, to trace malloc() in libc:
SEC("uprobe/libc.so.6:malloc")
...or to trace function foo2 in /usr/bin/foo:
SEC("uprobe//usr/bin/foo:foo2")
Auto-attach is done for all tasks (pid -1). prog can be an absolute
path or simply a program/library name; in the latter case, we use
PATH/LD_LIBRARY_PATH to resolve the full path, falling back to
standard locations (/usr/bin:/usr/sbin or /usr/lib64:/usr/lib) if
the file is not found via environment-variable specified locations.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1648654000-21758-4-git-send-email-alan.maguire@oracle.com
Diffstat (limited to 'tools/lib')
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 74 |
1 files changed, 72 insertions, 2 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index f6e5a0217841..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), @@ -10845,6 +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, |