netdev - Re: [PATCH bpf-next v6 2/2] selftests/bpf: Add testcase for bpf_task_under

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: <CA+khW7hZb6EJcoXUzkvrHKztsQ_J4cN+RRQjF-a73A8zE8S_NA@mail.gmail.com>
Date: Fri, 5 May 2023 00:13:52 -0700
From: Hao Luo <haoluo@...gle.com>
To: Feng zhou <zhoufeng.zf@...edance.com>
Cc: martin.lau@...ux.dev, ast@...nel.org, daniel@...earbox.net, 
	andrii@...nel.org, song@...nel.org, yhs@...com, john.fastabend@...il.com, 
	kpsingh@...nel.org, sdf@...gle.com, jolsa@...nel.org, davem@...emloft.net, 
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, mykolal@...com, 
	shuah@...nel.org, bpf@...r.kernel.org, linux-kernel@...r.kernel.org, 
	netdev@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	yangzhenze@...edance.com, wangdongdong.6@...edance.com
Subject: Re: [PATCH bpf-next v6 2/2] selftests/bpf: Add testcase for bpf_task_under_cgroup

On Thu, May 4, 2023 at 11:08 PM Feng zhou <zhoufeng.zf@...edance.com> wrote:
>
> From: Feng Zhou <zhoufeng.zf@...edance.com>
>
> test_progs:
> Tests new kfunc bpf_task_under_cgroup().
>
> The bpf program saves the new task's pid within a given cgroup to
> the remote_pid, which is convenient for the user-mode program to
> verify the test correctness.
>
> The user-mode program creates its own mount namespace, and mounts the
> cgroupsv2 hierarchy in there, call the fork syscall, then check if
> remote_pid and local_pid are unequal.
>
> Signed-off-by: Feng Zhou <zhoufeng.zf@...edance.com>
> Acked-by: Yonghong Song <yhs@...com>
> ---

Hi Feng,

I have a comment about the methodology of the test, but the patch
looks ok to me. Why do we have to test via a tracing program? I think
what we need is just a task and a cgroup. Since we have the kfunc
bpf_task_from_pid() and bpf_cgroup_from_id(), we can write a syscall
program which takes a pid and a cgroup id as input and get the task
and cgroup objects directly in the program.

I like testing via a syscall program because it doesn't depend on the
newtask tracepoint and it should be simpler. But I'm ok with the
current version of the patch, just have some thoughts.

Hao