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From: Sargun Dhillon <sargun@sargun.me>
To: Kees Cook <keescook@chromium.org>
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 3/3] selftests/seccomp: Test SECCOMP_IOCTL_NOTIF_ADDFD
Date: Fri, 29 May 2020 18:46:07 +0000	[thread overview]
Message-ID: <20200529184606.GB11153@ircssh-2.c.rugged-nimbus-611.internal> (raw)
In-Reply-To: <202005290036.3FEFFDA@keescook>

On Fri, May 29, 2020 at 12:41:51AM -0700, Kees Cook wrote:
> On Thu, May 28, 2020 at 04:08:58AM -0700, Sargun Dhillon wrote:
> > +	EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp), 0);
> > +
> > +	nextid = req.id + 1;
> > +
> > +	/* Wait for getppid to be called for the second time */
> > +	sleep(1);
> 
> I always rebel at finding "sleep" in tests. ;) Is this needed? IIUC,
> userspace will immediately see EINPROGRESS after the NOTIF_SEND
> finishes, yes?
> 
> Otherwise, yes, this looks good.
> 
> -- 
> Kees Cook
I'm open to better suggestions, but there's a race where if getppid
is not called before the second SECCOMP_IOCTL_NOTIF_ADDFD is called,
you will just get an ENOENT, since the notification ID is not found.

The other approach is to "poll" the child, and wait for it to enter
the second syscall. Calling receive beforehand doesn't work because
it moves the state of the notification in the kernel to received,
and then the kernel doesn't error with EINPROGRESS.

  parent reply	other threads:[~2020-05-29 18:46 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
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 [this message]
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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