From: Kees Cook <keescook@chromium.org>
To: Sargun Dhillon <sargun@sargun.me>
Cc: christian.brauner@ubuntu.com,
containers@lists.linux-foundation.org, cyphar@cyphar.com,
jannh@google.com, jeffv@google.com, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, palmer@google.com,
rsesek@google.com, tycho@tycho.ws,
Matt Denton <mpdenton@google.com>
Subject: Re: [PATCH v2 1/3] seccomp: Add find_notification helper
Date: Fri, 29 May 2020 13:14:56 -0700 [thread overview]
Message-ID: <202005291309.6183EC0604@keescook> (raw)
In-Reply-To: <20200529174037.GA11153@ircssh-2.c.rugged-nimbus-611.internal>
On Fri, May 29, 2020 at 05:40:38PM +0000, Sargun Dhillon wrote:
> >
> > While the comment is good, let's actually enforce this with:
> >
> > if (WARN_ON(!mutex_is_locked(&filter->notif_lock)))
> > return NULL;
> >
> I don't see much use of lockdep in seccomp (well, any), but
> wouldn't a stronger statement be to use lockdep, and just have:
>
> lockdep_assert_held(&filter->notify_lock);
>
> As that checks that the lock is held by the current task.
/me slaps his forehead
Yes. I need more coffee or something. Yes, I meant
lockdep_assert_held(), and now I need to go fix my pstore series since I
confused myself into the wrong function and using it so many times in
pstore overwrote the correct function in my head. Thank you!
> Although, that does put this check behind lockdep, which means
> that running in "normal" circumstances is less safe (but faster?).
Now, that's fine. The check needs to be "am *I* holding this mutex?" and
I don't think anything except lockdep can do that.
--
Kees Cook
next prev parent reply other threads:[~2020-05-29 20:15 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-28 11:08 [PATCH v2 0/3] Add seccomp notifier ioctl that enables adding fds Sargun Dhillon
2020-05-28 11:08 ` [PATCH v2 1/3] seccomp: Add find_notification helper Sargun Dhillon
2020-05-29 6:23 ` Kees Cook
2020-05-29 17:40 ` Sargun Dhillon
2020-05-29 20:14 ` Kees Cook [this message]
2020-05-29 9:57 ` Christian Brauner
2020-05-28 11:08 ` [PATCH v2 2/3] seccomp: Introduce addfd ioctl to seccomp user notifier Sargun Dhillon
2020-05-29 7:31 ` Kees Cook
2020-05-29 7:38 ` Christian Brauner
2020-05-29 7:45 ` Kees Cook
2020-05-30 1:10 ` Sargun Dhillon
2020-05-30 2:43 ` Kees Cook
2020-05-30 3:17 ` Jann Horn
2020-05-30 5:22 ` Kees Cook
2020-05-30 13:58 ` Christian Brauner
2020-05-30 16:09 ` Kees Cook
2020-05-30 3:58 ` Sargun Dhillon
2020-05-30 5:47 ` Kees Cook
2020-05-30 14:13 ` Christian Brauner
2020-05-30 16:14 ` Kees Cook
2020-05-30 16:21 ` Christian Brauner
2020-05-30 14:08 ` Al Viro
2020-05-30 16:07 ` Kees Cook
2020-06-01 19:02 ` Sargun Dhillon
2020-06-01 19:59 ` Kees Cook
2020-05-29 9:24 ` Giuseppe Scrivano
2020-05-29 10:32 ` Christian Brauner
2020-05-29 13:31 ` Christian Brauner
2020-05-29 22:35 ` Sargun Dhillon
2020-05-28 11:08 ` [PATCH v2 3/3] selftests/seccomp: Test SECCOMP_IOCTL_NOTIF_ADDFD Sargun Dhillon
2020-05-29 7:41 ` Kees Cook
2020-05-29 13:29 ` Tycho Andersen
2020-05-29 18:46 ` Sargun Dhillon
2020-05-29 19:12 ` Tycho Andersen
2020-05-29 20:09 ` Kees Cook
2020-05-29 13:30 ` [PATCH v2 0/3] Add seccomp notifier ioctl that enables adding fds Tycho Andersen
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