linux-kernel - [PATCH bpf-next v2 2/3] bpf: Add log for attaching tracing programs to functions in deny list

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250714120408.1627128-3-mannkafai@gmail.com>
Date: Mon, 14 Jul 2025 20:04:07 +0800
From: KaFai Wan <mannkafai@...il.com>
To: ast@...nel.org,
	daniel@...earbox.net,
	john.fastabend@...il.com,
	andrii@...nel.org,
	martin.lau@...ux.dev,
	eddyz87@...il.com,
	song@...nel.org,
	yonghong.song@...ux.dev,
	kpsingh@...nel.org,
	sdf@...ichev.me,
	haoluo@...gle.com,
	jolsa@...nel.org,
	mykolal@...com,
	shuah@...nel.org,
	mannkafai@...il.com,
	laoar.shao@...il.com,
	linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	leon.hwang@...ux.dev
Subject: [PATCH bpf-next v2 2/3] 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 migrate_disable() from log.

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

Suggested-by: Leon Hwang <leon.hwang@...ux.dev>
Signed-off-by: KaFai Wan <mannkafai@...il.com>
---
 kernel/bpf/verifier.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 00d287814f12..c24c0d57e595 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -23942,6 +23942,8 @@ 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) &&
-- 
2.43.0