From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
Jiri Olsa <jolsa@redhat.com>,
Eelco Chaudron <echaudro@redhat.com>,
KP Singh <kpsingh@chromium.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH bpf-next v8 01/11] bpf: disallow attaching modify_return tracing functions to other BPF programs
Date: Tue, 22 Sep 2020 20:38:34 +0200 [thread overview]
Message-ID: <160079991486.8301.10483022567832542496.stgit@toke.dk> (raw)
In-Reply-To: <160079991372.8301.10648588027560707258.stgit@toke.dk>
From: Toke Høiland-Jørgensen <toke@redhat.com>
From the checks and commit messages for modify_return, it seems it was
never the intention that it should be possible to attach a tracing program
with expected_attach_type == BPF_MODIFY_RETURN to another BPF program.
However, check_attach_modify_return() will only look at the function name,
so if the target function starts with "security_", the attach will be
allowed even for bpf2bpf attachment.
Fix this oversight by also blocking the modification if a target program is
supplied.
Fixes: 18644cec714a ("bpf: Fix use-after-free in fmod_ret check")
Fixes: 6ba43b761c41 ("bpf: Attachment verification for BPF_MODIFY_RETURN")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
kernel/bpf/verifier.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 15ab889b0a3f..797e2b0d8bc2 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11471,6 +11471,11 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
verbose(env, "%s is not sleepable\n",
prog->aux->attach_func_name);
} else if (prog->expected_attach_type == BPF_MODIFY_RETURN) {
+ if (tgt_prog) {
+ verbose(env, "can't modify return codes of BPF programs\n");
+ ret = -EINVAL;
+ goto out;
+ }
ret = check_attach_modify_return(prog, addr);
if (ret)
verbose(env, "%s() is not modifiable\n",
next prev parent reply other threads:[~2020-09-22 18:39 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 18:38 [PATCH bpf-next v8 00/11] bpf: Support multi-attach for freplace programs Toke Høiland-Jørgensen
2020-09-22 18:38 ` Toke Høiland-Jørgensen [this message]
2020-09-23 17:25 ` [PATCH bpf-next v8 01/11] bpf: disallow attaching modify_return tracing functions to other BPF programs Andrii Nakryiko
2020-09-22 18:38 ` [PATCH bpf-next v8 02/11] bpf: change logging calls from verbose() to bpf_log() and use log pointer Toke Høiland-Jørgensen
2020-09-22 18:38 ` [PATCH bpf-next v8 03/11] bpf: verifier: refactor check_attach_btf_id() Toke Høiland-Jørgensen
2020-09-23 23:54 ` Alexei Starovoitov
2020-09-22 18:38 ` [PATCH bpf-next v8 04/11] bpf: move prog->aux->linked_prog and trampoline into bpf_link on attach Toke Høiland-Jørgensen
2020-09-24 0:14 ` Alexei Starovoitov
2020-09-24 14:34 ` Toke Høiland-Jørgensen
2020-09-24 15:43 ` Alexei Starovoitov
2020-09-24 21:30 ` Toke Høiland-Jørgensen
2020-09-24 20:40 ` Andrii Nakryiko
2020-09-24 21:24 ` Toke Høiland-Jørgensen
2020-09-24 21:59 ` Andrii Nakryiko
2020-09-24 22:20 ` Toke Høiland-Jørgensen
2020-09-24 22:37 ` Andrii Nakryiko
2020-09-24 23:13 ` Toke Høiland-Jørgensen
2020-09-24 21:59 ` Toke Høiland-Jørgensen
2020-09-25 15:45 ` Alexei Starovoitov
2020-09-25 20:57 ` Toke Høiland-Jørgensen
2020-09-22 18:38 ` [PATCH bpf-next v8 05/11] bpf: support attaching freplace programs to multiple attach points Toke Høiland-Jørgensen
2020-09-24 1:04 ` Alexei Starovoitov
2020-09-22 18:38 ` [PATCH bpf-next v8 06/11] bpf: Fix context type resolving for extension programs Toke Høiland-Jørgensen
2020-09-22 18:38 ` [PATCH bpf-next v8 07/11] libbpf: add support for freplace attachment in bpf_link_create Toke Høiland-Jørgensen
2020-09-23 17:28 ` Andrii Nakryiko
2020-09-23 20:58 ` Toke Høiland-Jørgensen
2020-09-22 18:38 ` [PATCH bpf-next v8 08/11] selftests: add test for multiple attachments of freplace program Toke Høiland-Jørgensen
2020-09-22 18:38 ` [PATCH bpf-next v8 09/11] selftests/bpf: Adding test for arg dereference in extension trace Toke Høiland-Jørgensen
2020-09-22 18:38 ` [PATCH bpf-next v8 10/11] selftests: Add selftest for disallowing modify_return attachment to freplace Toke Høiland-Jørgensen
2020-09-22 18:38 ` [PATCH bpf-next v8 11/11] selftests: Remove fmod_ret from benchmarks and test_overhead Toke Høiland-Jørgensen
2020-09-23 17:40 ` Andrii Nakryiko
2020-09-24 1:08 ` Alexei Starovoitov
2020-09-24 1:38 ` Andrii Nakryiko
2020-09-24 23:19 ` Toke Høiland-Jørgensen
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