From: Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Daniel Borkmann <daniel@iogearbox.net>,
ast@kernel.org
Cc: eddyz87@gmail.com, info@starlabs.sg, bpf@vger.kernel.org
Subject: Re: [PATCH bpf 1/4] bpf: Add KF_PERFMON kfunc flag
Date: Thu, 10 Sep 2026 16:21:27 +0100 [thread overview]
Message-ID: <79d579fd-7392-48ab-83da-454599217981@gmail.com> (raw)
In-Reply-To: <DLBQGB3CXTSB.EXQVL3ZIQ3QO@gmail.com>
On 9/10/26 4:14 PM, Kumar Kartikeya Dwivedi wrote:
> On Thu Sep 10, 2026 at 5:03 PM CEST, Mykyta Yatsenko wrote:
>> On 9/10/26 3:21 PM, Daniel Borkmann wrote:
>>> Tracing related BPF helpers e.g. under bpf_base_func_proto() are gated
>>> behind CAP_PERFMON. However, the same is currently not true for kfuncs
>>> and they are accessible via plain CAP_BPF. Add a new KF_PERFMON flag
>>> which can be used such that check_kfunc_call() ensures env->allow_ptr_leaks
>>> is permitted. This follows similar pattern to existing KF_DESTRUCTIVE flag.
>>>
>>
>> This problem has been reported and patch sent some time ago:
>> https://lore.kernel.org/all/20260615-f01-07-dynptr-probe-read-cap-v1-0-e626cd61a381@mails.tsinghua.edu.cn/
>>
>
> We ended up discussing this and decided to go ahead, since it's a bit weird to
> continue to have the discrepancy against helpers that have similar restrictions.
> In practice it won't matter much to actual users, but easier to just fix it and
> put the thing to rest. This one is also a more comprehensive fix compared to
> Nuoqi's.
>
Thanks for the context, appreciate it!>> [...]
next prev parent reply other threads:[~2026-09-10 15:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-10 14:21 [PATCH bpf 1/4] bpf: Add KF_PERFMON kfunc flag Daniel Borkmann
2026-09-10 14:21 ` [PATCH bpf 2/4] bpf: Require CAP_PERFMON for kfuncs reading memory Daniel Borkmann
2026-09-10 15:10 ` bot+bpf-ci
2026-09-10 15:41 ` Alexei Starovoitov
2026-09-10 15:53 ` Daniel Borkmann
2026-09-10 14:21 ` [PATCH bpf 3/4] bpf: Require CAP_PERFMON for untrusted read-only memory reads Daniel Borkmann
2026-09-10 15:42 ` Alexei Starovoitov
2026-09-10 14:21 ` [PATCH bpf 4/4] selftests/bpf: Add tests for the KF_PERFMON gates Daniel Borkmann
2026-09-10 15:03 ` [PATCH bpf 1/4] bpf: Add KF_PERFMON kfunc flag Mykyta Yatsenko
2026-09-10 15:14 ` Kumar Kartikeya Dwivedi
2026-09-10 15:21 ` Mykyta Yatsenko [this message]
2026-09-10 15:10 ` bot+bpf-ci
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