Commit 863aab3d authored by KaFai Wan's avatar KaFai Wan Committed by Alexei Starovoitov
Browse files

bpf: Add log for attaching tracing programs to functions in deny list 



Show the rejected function name when attaching tracing programs to
functions in deny list.

With this change, we know why tracing programs can't attach to functions
like __rcu_read_lock() from log.

$ ./fentry
libbpf: prog '__rcu_read_lock': BPF program load failed: -EINVAL
libbpf: prog '__rcu_read_lock': -- BEGIN PROG LOAD LOG --
Attaching tracing programs to function '__rcu_read_lock' is rejected.

Suggested-by: default avatarLeon Hwang <leon.hwang@linux.dev>
Signed-off-by: default avatarKaFai Wan <kafai.wan@linux.dev>
Acked-by: default avatarYafang Shao <laoar.shao@gmail.com>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250724151454.499040-3-kafai.wan@linux.dev


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent a5a6b29a

kernel/bpf/verifier.c

+2 −0
Original line number Diff line number Diff line
@@ -23981,6 +23981,8 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) 
			return ret;

	} else if (prog->type == BPF_PROG_TYPE_TRACING &&

		   btf_id_set_contains(&btf_id_deny, btf_id)) {

		verbose(env, "Attaching tracing programs to function '%s' is rejected.\n",

			tgt_info.tgt_name);

		return -EINVAL;

	} else if ((prog->expected_attach_type == BPF_TRACE_FEXIT ||

		   prog->expected_attach_type == BPF_MODIFY_RETURN) &&