From: Christian Brauner <christian.brauner@ubuntu.com>
To: Tycho Andersen <tycho@tycho.ws>
Cc: linux-kernel@vger.kernel.org, Kees Cook <keescook@chromium.org>,
Andy Lutomirski <luto@kernel.org>,
Matt Denton <mpdenton@google.com>,
Sargun Dhillon <sargun@sargun.me>, Jann Horn <jannh@google.com>,
Chris Palmer <palmer@google.com>,
Aleksa Sarai <cyphar@cyphar.com>,
Robert Sesek <rsesek@google.com>,
Jeffrey Vander Stoep <jeffv@google.com>,
Linux Containers <containers@lists.linux-foundation.org>
Subject: Re: [PATCH 1/2] seccomp: notify user trap about unused filter
Date: Wed, 27 May 2020 17:35:04 +0200 [thread overview]
Message-ID: <20200527153504.d7va44xn75fbzyrr@wittgenstein> (raw)
In-Reply-To: <20200527152559.GB4153131@cisco>
On Wed, May 27, 2020 at 09:25:59AM -0600, Tycho Andersen wrote:
> On Wed, May 27, 2020 at 01:19:01PM +0200, Christian Brauner wrote:
> > +void seccomp_filter_notify(const struct task_struct *tsk)
> > +{
> > + struct seccomp_filter *orig = tsk->seccomp.filter;
> > +
> > + while (orig && refcount_dec_and_test(&orig->live)) {
> > + if (waitqueue_active(&orig->wqh))
> > + wake_up_poll(&orig->wqh, EPOLLHUP);
> > + orig = orig->prev;
> > + }
> > +}
>
> Is there a reason this can't live in put_seccomp_filter()?
put_seccomp_filter() is called from free_task() which in turn gets
called via delayed_put_task_struct through call_rcu() so the
notification will happen at some point whereas you'd often want the
notification to happen at reliable point. This is why most of that stuff
happens in release_task() which is called in the exit path when the task
is finally marked as dead. This is similar to how cgroup_release() is
called from release_task() whereas cgroup_free() is called from
free_task() or other stuff.
next prev parent reply other threads:[~2020-05-27 15:35 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 11:19 [PATCH 1/2] seccomp: notify user trap about unused filter Christian Brauner
2020-05-27 11:19 ` [PATCH 2/2] tests: test seccomp filter notifications Christian Brauner
2020-05-27 15:25 ` [PATCH 1/2] seccomp: notify user trap about unused filter Tycho Andersen
2020-05-27 15:35 ` Christian Brauner [this message]
2020-05-27 17:37 ` Sargun Dhillon
2020-05-27 19:13 ` Christian Brauner
2020-05-27 21:43 ` Kees Cook
2020-05-27 21:52 ` Tycho Andersen
2020-05-27 22:36 ` Kees Cook
2020-05-27 22:56 ` Tycho Andersen
2020-05-28 1:50 ` Kees Cook
2020-05-27 22:05 ` Christian Brauner
2020-05-27 22:37 ` Kees Cook
2020-05-27 22:45 ` Christian Brauner
2020-05-27 23:16 ` Christian Brauner
2020-05-28 1:59 ` Kees Cook
2020-05-28 4:14 ` Jann Horn
2020-05-28 14:16 ` Christian Brauner
2020-05-28 14:39 ` Christian Brauner
2020-05-28 1:49 ` Kees Cook
2020-05-28 4:04 ` Jann Horn
2020-05-28 9:57 ` Christian Brauner
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