linux-kernel - Re: [PATCH bpf-next v2 1/3] selftests/bpf: do not disable /dev/null device access in cgroup dev test

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3d809ae0-d228-4ba0-baa4-c1b299024c55@bootlin.com>
Date: Mon, 29 Jul 2024 19:30:55 +0200
From: Alexis Lothoré <alexis.lothore@...tlin.com>
To: Alan Maguire <alan.maguire@...cle.com>,
 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>, Mykola Lysenko <mykolal@...com>,
 Shuah Khan <shuah@...nel.org>
Cc: ebpf@...uxfoundation.org, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>, bpf@...r.kernel.org,
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v2 1/3] selftests/bpf: do not disable /dev/null
 device access in cgroup dev test

Hello Alan,

On 7/29/24 18:59, Alan Maguire wrote:
> On 29/07/2024 09:20, Alexis Lothoré (eBPF Foundation) wrote:
>> test_dev_cgroup currently loads a small bpf program allowing any access on
>> urandom and zero devices, disabling access to any other device. It makes
>> migrating this test to test_progs impossible, since this one manipulates
>> extensively /dev/null.
>>
>> Allow /dev/null manipulation in dev_cgroup program to make its usage in
>> test_progs framework possible. Update test_dev_cgroup.c as well to match
>> this change while it has not been removed.
>>
>> Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
>> ---
>>  tools/testing/selftests/bpf/progs/dev_cgroup.c |  4 ++--
>>  tools/testing/selftests/bpf/test_dev_cgroup.c  | 18 +++++++++---------
> 
> Not a big deal, but I found it a bit confusing that this file was
> modified then deleted in patch 2. Would it work having patch 1 stop
> building the standalone test/remove it and .gitignore entry, patch 2
> updating progs/dev_cgroup.c to allow /dev/zero, /dev/urandom access,
> patch 3 add cgroup_dev.c test support, and patch 4 add the device type
> subtest? Or are there issues with doing things that way? Thanks!

I've done this to make sure that at any point in the git history, there is one
working test for the targeted feature, either the old or the new one. I've done
it this way because the old test also helped me validate the new one while
developing it, but also because if at some point there is a (major) issue with
the new test, reverting only the relevant commit brings back the old test while
disabling the new one.

But maybe this concern is not worth the trouble (especially since the old tests
are not run automatically) ? If that's indeed the case, I can do it the way you
are suggesting :)

Thanks,

Alexis

-- 
Alexis Lothoré, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com