From: "Michal Koutný" <mkoutny@suse.com>
To: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Tejun Heo <tj@kernel.org>,
Linus Torvalds <torvalds@linuxfoundation.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>, Kees Cook <keescook@chromium.org>,
Oleg Nesterov <oleg@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jim Newsome <jnewsome@torproject.org>,
Alexey Gladkov <legion@kernel.org>,
Security Officers <security@kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Jann Horn <jannh@google.com>
Subject: Re: [PATCH] exit: Retain nsproxy for exit_task_work() work entries
Date: Thu, 9 Dec 2021 15:47:00 +0100 [thread overview]
Message-ID: <20211209144700.GC63648@blackbody.suse.cz> (raw)
In-Reply-To: <20211209140826.kc2xvvwxrdrwmrtj@wittgenstein>
On Thu, Dec 09, 2021 at 03:08:26PM +0100, Christian Brauner <christian.brauner@ubuntu.com> wrote:
> send_sig() isn't used that was changed in response to a review. I'm
> confused.
Sorry for ambiguity, I meant this instance [1].
> Kill and freeze only do time permission checking at open. Why would you
> introduce another write time check?
Let's have a cgroup G with tasks t1,...,tn (run by user u) and some
monitoring tasks m1,...,mk belonging to a different user v != u.
Currently u can kill also the tasks of v -- I'm not sure if that's
intentional. My argument would apply if it wasn't -- it'd be suscebtible
to similar abuse, i.e. passing the opened fd to a more privileged
process to kill also v's tasks. (But if the intention is to be able to
kill anyone in the cgroup, then it likely doesn't matter.)
Michal
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/cgroup/cgroup.c?h=v5.16-rc4#n3762
next prev parent reply other threads:[~2021-12-09 14:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-08 18:05 [PATCH] exit: Retain nsproxy for exit_task_work() work entries Michal Koutný
2021-12-08 18:45 ` Eric W. Biederman
2021-12-08 19:06 ` Tejun Heo
2021-12-08 19:39 ` Linus Torvalds
2021-12-08 19:49 ` Tejun Heo
2021-12-08 23:07 ` Tejun Heo
2021-12-09 13:44 ` Michal Koutný
2021-12-09 14:08 ` Christian Brauner
2021-12-09 14:47 ` Michal Koutný [this message]
2021-12-09 15:06 ` Christian Brauner
2021-12-09 16:39 ` Michal Koutný
2021-12-10 23:12 ` Michal Koutný
2021-12-13 15:24 ` Eric W. Biederman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211209144700.GC63648@blackbody.suse.cz \
--to=mkoutny@suse.com \
--cc=axboe@kernel.dk \
--cc=christian.brauner@ubuntu.com \
--cc=ebiederm@xmission.com \
--cc=jannh@google.com \
--cc=jnewsome@torproject.org \
--cc=keescook@chromium.org \
--cc=legion@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=oleg@redhat.com \
--cc=peterz@infradead.org \
--cc=security@kernel.org \
--cc=tglx@linutronix.de \
--cc=tj@kernel.org \
--cc=torvalds@linuxfoundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox