From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, KP Singh <kpsingh@kernel.org>,
syzbot+983941aa85af6ded1fd9@syzkaller.appspotmail.com,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>
Subject: Re: [PATCH bpf 1/2] xdp: check prog type before updating BPF link
Date: Fri, 07 Jan 2022 22:26:07 +0100 [thread overview]
Message-ID: <87sftz8cgg.fsf@toke.dk> (raw)
In-Reply-To: <CAEf4BzbRxwbJQFZHvB-hBj1A+364Jua4KJgkL+D_9PKsj7jKSg@mail.gmail.com>
Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
> On Fri, Jan 7, 2022 at 10:31 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>
>> The bpf_xdp_link_update() function didn't check the program type before
>> updating the program, which made it possible to install any program type as
>> an XDP program, which is obviously not good. Syzbot managed to trigger this
>> by swapping in an LWT program on the XDP hook which would crash in a helper
>> call.
>>
>> Fix this by adding a check and bailing out if the types don't match.
>>
>> Fixes: 026a4c28e1db ("bpf, xdp: Implement LINK_UPDATE for BPF XDP link")
>> Reported-by: syzbot+983941aa85af6ded1fd9@syzkaller.appspotmail.com
>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> ---
>
> The fix looks good to me, thanks. I'd love it if this was done
> generically in link_update, but each link type has its own locking
> schema for link->prog, so I didn't figure out a way to do this in a
> centralized way.
Yeah, moving it to be a generic check was my first thought as well, but
I came to the same conclusion :)
> Acked-by: Andrii Nakryiko <andrii@kernel.org>
Thanks!
-Toke
prev parent reply other threads:[~2022-01-07 21:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-07 18:30 [PATCH bpf 1/2] xdp: check prog type before updating BPF link Toke Høiland-Jørgensen
2022-01-07 18:30 ` [PATCH bpf 2/2] bpf/selftests: Add check for updating XDP bpf_link with wrong program type Toke Høiland-Jørgensen
2022-01-07 21:08 ` Andrii Nakryiko
2022-01-07 21:23 ` Toke Høiland-Jørgensen
2022-01-07 21:30 ` Andrii Nakryiko
2022-01-07 21:17 ` [PATCH bpf 1/2] xdp: check prog type before updating BPF link Andrii Nakryiko
2022-01-07 21:26 ` Toke Høiland-Jørgensen [this message]
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