There is currently no way to discover the target of a tracing program
attachment after the fact. Add this information to bpf_link_info and return
it when querying the bpf_link fd.
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
---
include/linux/bpf_verifier.h | 9 +++++++++
include/uapi/linux/bpf.h | 2 ++
kernel/bpf/syscall.c | 3 +++
tools/include/uapi/linux/bpf.h | 2 ++
4 files changed, 16 insertions(+)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 51c2ffa3d901..6023a1367853 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -487,6 +487,15 @@ static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog,
return ((u64)btf_obj_id(btf) << 32) | 0x80000000 | btf_id;
}
+/* unpack the IDs from the key as constructed above */
+static inline void bpf_trampoline_unpack_key(u64 key, u32 *obj_id, u32 *btf_id)
+{
+ if (obj_id)
+ *obj_id = key >> 32;
+ if (btf_id)
+ *btf_id = key & 0x7FFFFFFF;
+}
+
int bpf_check_attach_target(struct bpf_verifier_log *log,
const struct bpf_prog *prog,
const struct bpf_prog *tgt_prog,
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 49371eba98ba..397884396671 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5379,6 +5379,8 @@ struct bpf_link_info {
} raw_tracepoint;
struct {
__u32 attach_type;
+ __u32 target_obj_id; /* prog_id for PROG_EXT, otherwise btf object id */
+ __u32 target_btf_id; /* BTF type id inside the object */
} tracing;
struct {
__u64 cgroup_id;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 6428634da57e..fd495190115e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2551,6 +2551,9 @@ static int bpf_tracing_link_fill_link_info(const struct bpf_link *link,
container_of(link, struct bpf_tracing_link, link);
info->tracing.attach_type = tr_link->attach_type;
+ bpf_trampoline_unpack_key(tr_link->trampoline->key,
+ &info->tracing.target_obj_id,
+ &info->tracing.target_btf_id);
return 0;
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 69902603012c..1a240be873d7 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5373,6 +5373,8 @@ struct bpf_link_info {
} raw_tracepoint;
struct {
__u32 attach_type;
+ __u32 target_obj_id; /* prog_id for PROG_EXT, otherwise btf object id */
+ __u32 target_btf_id; /* BTF type id inside the object */
} tracing;
struct {
__u64 cgroup_id;
--
2.31.1
