};
};
-struct bpf_sec_def;
-
-typedef int (*init_fn_t)(struct bpf_program *prog, long cookie);
-typedef int (*preload_fn_t)(struct bpf_program *prog, struct bpf_prog_load_opts *opts, long cookie);
-typedef struct bpf_link *(*attach_fn_t)(const struct bpf_program *prog, long cookie);
+typedef int (*libbpf_prog_setup_fn_t)(struct bpf_program *prog, long cookie);
+typedef int (*libbpf_prog_prepare_load_fn_t)(struct bpf_program *prog,
+ struct bpf_prog_load_opts *opts, long cookie);
+/* If auto-attach is not supported, callback should return 0 and set link to NULL */
+typedef int (*libbpf_prog_attach_fn_t)(const struct bpf_program *prog, long cookie,
+ struct bpf_link **link);
/* stored as sec_def->cookie for all libbpf-supported SEC()s */
enum sec_def_flags {
enum bpf_attach_type expected_attach_type;
long cookie;
- init_fn_t init_fn;
- preload_fn_t preload_fn;
- attach_fn_t attach_fn;
+ libbpf_prog_setup_fn_t prog_setup_fn;
+ libbpf_prog_prepare_load_fn_t prog_prepare_load_fn;
+ libbpf_prog_attach_fn_t prog_attach_fn;
};
/*
static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attach_name,
int *btf_obj_fd, int *btf_type_id);
-/* this is called as prog->sec_def->preload_fn for libbpf-supported sec_defs */
-static int libbpf_preload_prog(struct bpf_program *prog,
- struct bpf_prog_load_opts *opts, long cookie)
+/* this is called as prog->sec_def->prog_prepare_load_fn for libbpf-supported sec_defs */
+static int libbpf_prepare_prog_load(struct bpf_program *prog,
+ struct bpf_prog_load_opts *opts, long cookie)
{
enum sec_def_flags def = cookie;
load_attr.fd_array = obj->fd_array;
/* adjust load_attr if sec_def provides custom preload callback */
- if (prog->sec_def && prog->sec_def->preload_fn) {
- err = prog->sec_def->preload_fn(prog, &load_attr, prog->sec_def->cookie);
+ if (prog->sec_def && prog->sec_def->prog_prepare_load_fn) {
+ err = prog->sec_def->prog_prepare_load_fn(prog, &load_attr, prog->sec_def->cookie);
if (err < 0) {
pr_warn("prog '%s': failed to prepare load attributes: %d\n",
prog->name, err);
/* sec_def can have custom callback which should be called
* after bpf_program is initialized to adjust its properties
*/
- if (prog->sec_def->init_fn) {
- err = prog->sec_def->init_fn(prog, prog->sec_def->cookie);
+ if (prog->sec_def->prog_setup_fn) {
+ err = prog->sec_def->prog_setup_fn(prog, prog->sec_def->cookie);
if (err < 0) {
pr_warn("prog '%s': failed to initialize: %d\n",
prog->name, err);
.prog_type = BPF_PROG_TYPE_##ptype, \
.expected_attach_type = atype, \
.cookie = (long)(flags), \
- .preload_fn = libbpf_preload_prog, \
+ .prog_prepare_load_fn = libbpf_prepare_prog_load, \
__VA_ARGS__ \
}
-static struct bpf_link *attach_kprobe(const struct bpf_program *prog, long cookie);
-static struct bpf_link *attach_tp(const struct bpf_program *prog, long cookie);
-static struct bpf_link *attach_raw_tp(const struct bpf_program *prog, long cookie);
-static struct bpf_link *attach_trace(const struct bpf_program *prog, long cookie);
-static struct bpf_link *attach_lsm(const struct bpf_program *prog, long cookie);
-static struct bpf_link *attach_iter(const struct bpf_program *prog, long cookie);
+static int attach_kprobe(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);
+static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static const struct bpf_sec_def section_defs[] = {
SEC_DEF("socket", SOCKET_FILTER, 0, SEC_NONE | SEC_SLOPPY_PFX),
const struct bpf_sec_def *sec_def = §ion_defs[i];
if (attach_type) {
- if (sec_def->preload_fn != libbpf_preload_prog)
+ if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
continue;
if (!(sec_def->cookie & SEC_ATTACHABLE))
return libbpf_err(-EINVAL);
}
- if (sec_def->preload_fn != libbpf_preload_prog)
+ if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
return libbpf_err(-EINVAL);
if (!(sec_def->cookie & SEC_ATTACHABLE))
return libbpf_err(-EINVAL);
return bpf_program__attach_kprobe_opts(prog, func_name, &opts);
}
-static struct bpf_link *attach_kprobe(const struct bpf_program *prog, long cookie)
+static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts);
unsigned long offset = 0;
- struct bpf_link *link;
const char *func_name;
char *func;
- int n, err;
+ int n;
opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe/");
if (opts.retprobe)
n = sscanf(func_name, "%m[a-zA-Z0-9_.]+%li", &func, &offset);
if (n < 1) {
- err = -EINVAL;
pr_warn("kprobe name is invalid: %s\n", func_name);
- return libbpf_err_ptr(err);
+ return -EINVAL;
}
if (opts.retprobe && offset != 0) {
free(func);
- err = -EINVAL;
pr_warn("kretprobes do not support offset specification\n");
- return libbpf_err_ptr(err);
+ return -EINVAL;
}
opts.offset = offset;
- link = bpf_program__attach_kprobe_opts(prog, func, &opts);
+ *link = bpf_program__attach_kprobe_opts(prog, func, &opts);
free(func);
- return link;
+ return libbpf_get_error(*link);
}
static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);
}
-static struct bpf_link *attach_tp(const struct bpf_program *prog, long cookie)
+static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
char *sec_name, *tp_cat, *tp_name;
- struct bpf_link *link;
sec_name = strdup(prog->sec_name);
if (!sec_name)
- return libbpf_err_ptr(-ENOMEM);
+ return -ENOMEM;
/* extract "tp/<category>/<name>" or "tracepoint/<category>/<name>" */
if (str_has_pfx(prog->sec_name, "tp/"))
tp_name = strchr(tp_cat, '/');
if (!tp_name) {
free(sec_name);
- return libbpf_err_ptr(-EINVAL);
+ return -EINVAL;
}
*tp_name = '\0';
tp_name++;
- link = bpf_program__attach_tracepoint(prog, tp_cat, tp_name);
+ *link = bpf_program__attach_tracepoint(prog, tp_cat, tp_name);
free(sec_name);
- return link;
+ return libbpf_get_error(*link);
}
struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
return link;
}
-static struct bpf_link *attach_raw_tp(const struct bpf_program *prog, long cookie)
+static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
static const char *const prefixes[] = {
"raw_tp/",
if (!tp_name) {
pr_warn("prog '%s': invalid section name '%s'\n",
prog->name, prog->sec_name);
- return libbpf_err_ptr(-EINVAL);
+ return -EINVAL;
}
- return bpf_program__attach_raw_tracepoint(prog, tp_name);
+ *link = bpf_program__attach_raw_tracepoint(prog, tp_name);
+ return libbpf_get_error(link);
}
/* Common logic for all BPF program types that attach to a btf_id */
return bpf_program__attach_btf_id(prog);
}
-static struct bpf_link *attach_trace(const struct bpf_program *prog, long cookie)
+static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
- return bpf_program__attach_trace(prog);
+ *link = bpf_program__attach_trace(prog);
+ return libbpf_get_error(*link);
}
-static struct bpf_link *attach_lsm(const struct bpf_program *prog, long cookie)
+static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
- return bpf_program__attach_lsm(prog);
+ *link = bpf_program__attach_lsm(prog);
+ return libbpf_get_error(*link);
}
static struct bpf_link *
return link;
}
-static struct bpf_link *attach_iter(const struct bpf_program *prog, long cookie)
+static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
- return bpf_program__attach_iter(prog, NULL);
+ *link = bpf_program__attach_iter(prog, NULL);
+ return libbpf_get_error(*link);
}
struct bpf_link *bpf_program__attach(const struct bpf_program *prog)
{
- if (!prog->sec_def || !prog->sec_def->attach_fn)
- return libbpf_err_ptr(-ESRCH);
+ struct bpf_link *link = NULL;
+ int err;
+
+ if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
+ return libbpf_err_ptr(-EOPNOTSUPP);
- return prog->sec_def->attach_fn(prog, prog->sec_def->cookie);
+ err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, &link);
+ if (err)
+ return libbpf_err_ptr(err);
+
+ /* When calling bpf_program__attach() explicitly, auto-attach support
+ * is expected to work, so NULL returned link is considered an error.
+ * This is different for skeleton's attach, see comment in
+ * bpf_object__attach_skeleton().
+ */
+ if (!link)
+ return libbpf_err_ptr(-EOPNOTSUPP);
+
+ return link;
}
static int bpf_link__detach_struct_ops(struct bpf_link *link)
continue;
/* auto-attaching not supported for this program */
- if (!prog->sec_def || !prog->sec_def->attach_fn)
+ if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
continue;
- *link = bpf_program__attach(prog);
- err = libbpf_get_error(*link);
+ /* if user already set the link manually, don't attempt auto-attach */
+ if (*link)
+ continue;
+
+ err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, link);
if (err) {
- pr_warn("failed to auto-attach program '%s': %d\n",
+ pr_warn("prog '%s': failed to auto-attach: %d\n",
bpf_program__name(prog), err);
return libbpf_err(err);
}
+
+ /* It's possible that for some SEC() definitions auto-attach
+ * is supported in some cases (e.g., if definition completely
+ * specifies target information), but is not in other cases.
+ * SEC("uprobe") is one such case. If user specified target
+ * binary and function name, such BPF program can be
+ * auto-attached. But if not, it shouldn't trigger skeleton's
+ * attach to fail. It should just be skipped.
+ * attach_fn signals such case with returning 0 (no error) and
+ * setting link to NULL.
+ */
}
return 0;