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From: Leon Hwang <leon.hwang@linux.dev>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Sanghyun Park <sanghyun.park.cnu@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Eduard Zingerman <eddyz87@gmail.com>,
	Kumar Kartikeya Dwivedi <memxor@gmail.com>,
	bpf@vger.kernel.org, John Fastabend <john.fastabend@gmail.com>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	Jiri Olsa <jolsa@kernel.org>,
	Emil Tsalapatis <emil@etsalapatis.com>,
	Ihor Solodrai <ihor.solodrai@linux.dev>,
	Stanislav Fomichev <sdf@fomichev.me>,
	Pu Lehui <pulehui@huawei.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next v3] bpf: Fix stack out-of-bounds write in cgroup link update
Date: Mon, 24 Aug 2026 13:04:38 +0800	[thread overview]
Message-ID: <68358803-57c9-4a89-9da3-fb5e12547e0f@linux.dev> (raw)
In-Reply-To: <CAEf4BzYM+b4E5S6ZCDcpEaw2uvdNPDVUdTgxUxkvCdM86DkubQ@mail.gmail.com>

On 22/8/26 03:35, Andrii Nakryiko wrote:
> On Fri, Aug 21, 2026 at 3:26 AM Leon Hwang <leon.hwang@linux.dev> wrote:
[...]
>>
>> Any issue of checking CAP_NET_ADMIN for BPF_LINK_UPDATE?
>>
>> If no, checking CAP_NET_ADMIN for BPF_LINK_UPDATE looks okay.
>>
> 
> Why do we need extra capability checks during LINK_UPDATE if we
> already performed the check during LINK_CREATE? If you pass link fd to
> some process that doesn't have CAP_NET_ADMIN, but has link fd and
> another validated prog fd, they should be able to update the
> underlying program without extra checks, IMO.
> 
What if a pinned link is updated by non-CAP_NET_ADMIN users? I (LLM)
verified the case by the selftest [1]. Is this case allowed intentionally?

[1] https://github.com/Asphaltt/bpf/commits/bpf/link-update-issue/v1/

Thanks,
Leon


  reply	other threads:[~2026-08-24  5:05 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-21  8:47 [PATCH bpf-next v3] bpf: Fix stack out-of-bounds write in cgroup link update Sanghyun Park
2026-08-21  9:41 ` bot+bpf-ci
2026-08-21 10:26 ` Leon Hwang
2026-08-21 19:35   ` Andrii Nakryiko
2026-08-24  5:04     ` Leon Hwang [this message]
2026-08-24 20:10       ` Andrii Nakryiko
2026-08-25  5:30         ` Leon Hwang
2026-08-21 13:41 ` Leon Hwang

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