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| author | Toke Høiland-Jørgensen <toke@redhat.com> | 2020-09-25 23:25:00 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-10-29 10:11:30 +0100 |
| commit | 9d6b33d27c250eb381d97297e40eb15f5586913d (patch) | |
| tree | 5acab6ed523cbc32a99fd5f884990343b53cf1d9 /kernel | |
| parent | 05ad722863103b860fcfea25827cbb9b68868ae2 (diff) | |
| download | linux-stable-9d6b33d27c250eb381d97297e40eb15f5586913d.tar.gz linux-stable-9d6b33d27c250eb381d97297e40eb15f5586913d.tar.bz2 linux-stable-9d6b33d27c250eb381d97297e40eb15f5586913d.zip | |
bpf: disallow attaching modify_return tracing functions to other BPF programs
[ Upstream commit 1af9270e908cd50a4f5d815c9b6f794c7d57ed07 ]
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")
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index fba52d9ec8fc..5b9d2cf06fc6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11046,6 +11046,11 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) } 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", |