linux-kernel - Re: [PATCH bpf-next v3 01/11] selftests/bpf: Fix caps for __xlated/jited

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Message-ID: <CAP01T742Td_U8=fs4DDrxWSdQcXEpGE=T6+WfJqBw_bqpXhb+g@mail.gmail.com>
Date: Thu, 1 May 2025 18:56:13 +0200
From: Kumar Kartikeya Dwivedi <memxor@...il.com>
To: Luis Gerhorst <luis.gerhorst@....de>
Cc: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>, 
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
	Jiri Olsa <jolsa@...nel.org>, Puranjay Mohan <puranjay@...nel.org>, 
	Xu Kuohai <xukuohai@...weicloud.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Hari Bathini <hbathini@...ux.ibm.com>, 
	Christophe Leroy <christophe.leroy@...roup.eu>, Naveen N Rao <naveen@...nel.org>, 
	Madhavan Srinivasan <maddy@...ux.ibm.com>, Michael Ellerman <mpe@...erman.id.au>, 
	Nicholas Piggin <npiggin@...il.com>, Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>, 
	Henriette Herzog <henriette.herzog@....de>, Saket Kumar Bhaskar <skb99@...ux.ibm.com>, 
	Cupertino Miranda <cupertino.miranda@...cle.com>, Jiayuan Chen <mrpre@....com>, 
	Matan Shachnai <m.shachnai@...il.com>, Dimitar Kanaliev <dimitar.kanaliev@...eground.com>, 
	Shung-Hsi Yu <shung-hsi.yu@...e.com>, Daniel Xu <dxu@...uu.xyz>, bpf@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH bpf-next v3 01/11] selftests/bpf: Fix caps for __xlated/jited_unpriv

On Thu, 1 May 2025 at 09:39, Luis Gerhorst <luis.gerhorst@....de> wrote:
>
> Currently, __xlated_unpriv and __jited_unpriv do not work because the
> BPF syscall will overwrite info.jited_prog_len and info.xlated_prog_len
> with 0 if the process is not bpf_capable(). This bug was not noticed
> before, because there is no test that actually uses
> __xlated_unpriv/__jited_unpriv.
>
> To resolve this, simply restore the capabilities earlier (but still
> after loading the program). Adding this here unconditionally is fine
> because the function first checks that the capabilities were initialized
> before attempting to restore them.
>
> This will be important later when we add tests that check whether a
> speculation barrier was inserted in the correct location.
>
> Signed-off-by: Luis Gerhorst <luis.gerhorst@....de>
> Fixes: 9c9f73391310 ("selftests/bpf: allow checking xlated programs in verifier_* tests")
> Fixes: 7d743e4c759c ("selftests/bpf: __jited test tag to check disassembly after jit")
> ---

Acked-by: Kumar Kartikeya Dwivedi <memxor@...il.com>