bpf_program__attach_uprobe_opts() requires a binary_path argument
specifying binary to instrument. Supporting simply specifying
"libc.so.6" or "foo" should be possible too.
Library search checks LD_LIBRARY_PATH, then /usr/lib64, /usr/lib.
This allows users to run BPF programs prefixed with
LD_LIBRARY_PATH=/path2/lib while still searching standard locations.
Similarly for non .so files, we check PATH and /usr/bin, /usr/sbin.
Path determination will be useful for auto-attach of BPF uprobe programs
using SEC() definition.
Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 50 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 43161fd..b577577 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -10320,6 +10320,45 @@ static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
return pfd;
}
+/* Get full path to program/shared library. */
+static int resolve_full_path(const char *file, char *result, size_t result_sz)
+{
+ char *search_paths[2];
+ int i;
+
+ if (strstr(file, ".so")) {
+ search_paths[0] = getenv("LD_LIBRARY_PATH");
+ search_paths[1] = (char *)"/usr/lib64:/usr/lib";
+ } else {
+ search_paths[0] = getenv("PATH");
+ search_paths[1] = (char *)"/usr/bin:/usr/sbin";
+ }
+
+ for (i = 0; i < ARRAY_SIZE(search_paths); i++) {
+ char *s, *search_path, *currpath, *saveptr = NULL;
+
+ if (!search_paths[i])
+ continue;
+ search_path = strdup(search_paths[i]);
+ s = search_path;
+ while ((currpath = strtok_r(s, ":", &saveptr)) != NULL) {
+ struct stat sb;
+
+ s = NULL;
+ snprintf(result, result_sz, "%s/%s", currpath, file);
+ /* ensure it is an executable file/link */
+ if (stat(result, &sb) == 0 && (sb.st_mode & (S_IFREG | S_IFLNK)) &&
+ (sb.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))) {
+ pr_debug("resolved '%s' to '%s'\n", file, result);
+ free(search_path);
+ return 0;
+ }
+ }
+ free(search_path);
+ }
+ 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,
@@ -10327,6 +10366,7 @@ static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
{
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;
@@ -10338,13 +10378,22 @@ static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
retprobe = OPTS_GET(opts, retprobe, false);
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("could not find full path for %s\n", binary_path);
+ return libbpf_err_ptr(err);
+ }
+ binary_path = full_binary_path;
+ }
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);
--
1.8.3.1
