From: Kees Cook <keescook@chromium.org>
To: Sargun Dhillon <sargun@sargun.me>
Cc: LKML <linux-kernel@vger.kernel.org>,
Linux Containers <containers@lists.linux-foundation.org>,
Rodrigo Campos <rodrigo@kinvolk.io>,
Christian Brauner <christian.brauner@ubuntu.com>,
Giuseppe Scrivano <gscrivan@redhat.com>,
Will Drewry <wad@chromium.org>,
Andy Lutomirski <luto@amacapital.net>,
Alban Crequy <alban@kinvolk.io>,
Tycho Andersen <tycho@tycho.pizza>
Subject: Re: [PATCH v3 2/2] selftests/seccomp: Add test for wait killable notifier
Date: Fri, 29 Apr 2022 15:43:17 -0700 [thread overview]
Message-ID: <202204291541.4438B18A@keescook> (raw)
In-Reply-To: <20220429223557.GB1267404@ircssh-3.c.rugged-nimbus-611.internal>
On Fri, Apr 29, 2022 at 10:35:57PM +0000, Sargun Dhillon wrote:
> On Fri, Apr 29, 2022 at 11:19:33AM -0700, Kees Cook wrote:
> > On Thu, Apr 28, 2022 at 07:31:13PM -0700, Sargun Dhillon wrote:
> > > +
> > > + ASSERT_EQ(socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sk_pair), 0);
> > > +
> > > + listener = user_notif_syscall(__NR_getppid,
> > > + SECCOMP_FILTER_FLAG_NEW_LISTENER |
> > > + SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV);
> > > + ASSERT_GE(listener, 0);
> > > +
> > > + pid = fork();
> > > + ASSERT_GE(pid, 0);
> > > +
> > > + if (pid == 0) {
> > > + close(sk_pair[0]);
> > > + handled = sk_pair[1];
> > > +
> > > + /* Setup the sigaction without SA_RESTART */
> > > + if (sigaction(SIGUSR1, &new_action, NULL)) {
> > > + perror("sigaction");
> > > + exit(1);
> > > + }
> > > +
> > > + /* Make sure that the syscall is completed (no EINTR) */
> > > + ret = syscall(__NR_getppid);
> > > + exit(ret != USER_NOTIF_MAGIC);
> > > + }
> > > +
> > > + while (get_proc_syscall(pid) != __NR_getppid &&
> > > + get_proc_stat(pid) != 'S')
> > > + nanosleep(&delay, NULL);
> > > +
> > > + EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
> > > + /* Kill the process to make sure it enters the wait_killable state */
> > > + EXPECT_EQ(kill(pid, SIGUSR1), 0);
> > > +
> > > + /* TASK_KILLABLE is considered D (Disk Sleep) state */
> > > + while (get_proc_stat(pid) != 'D')
> > > + nanosleep(&delay, NULL);
> >
> > Should a NOWAIT waitpid() happen in this loop to make sure this doesn't
> > spin forever?
> >
> > i.e. running these tests on a kernel that doesn't have the support
> > shouldn't hang -- yes it'll time out eventually but that's annoying. ;)
> >
> Wouldn't this bail already because user_notif_syscall would assert out
> since the kernel would reject the unknown flag?
Oh yeah, duh. :P
> I might make this a little helper function, something like:
> static void wait_for_state(struct __test_metadata *_metadata, pid_t pid, char wait_for) {
> /* 100 ms */
> struct timespec delay = { .tv_nsec = 100000000 };
> int status;
>
> while (get_proc_stat(pid) != wait_for) {
> ASSERT_EQ(waitpid(pid, &status, WNOHANG), 0) {
> if (WIFEXITED(status))
> TH_LOG("Process %d exited with error code %d", pid, WEXITSTATUS(status));
> else if (WIFSIGNALED(status))
> TH_LOG("Process %d exited due to signal %d", pid, WTERMSIG(status));
> else
> TH_LOG("Process %d exited due to unknown reason", pid);
> }
> nanosleep(&delay, NULL);
> }
> }
Yeah, though as you point out, that is likely overkill. :)
> > > + EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
> > > + /* Kill the process with a fatal signal */
> > > + EXPECT_EQ(kill(pid, SIGTERM), 0);
> > > +
> > > + EXPECT_EQ(waitpid(pid, &status, 0), pid);
> > > + EXPECT_EQ(true, WIFSIGNALED(status));
> > > + EXPECT_EQ(SIGTERM, WTERMSIG(status));
> > > +}
> >
> > Should there be a test validating the inverse of this, as in _without_
> > SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV, how should the above tests
> > behave?
> Don't we roughly get that from the user_notification_kill_in_middle
> and user_notification_signal?
Yeah, I guess that's true. Cool, cool.
> Although, I might cleanup the user_notification_signal test to disable
> SA_RESTART like these tests.
Sounds good, though maybe that can be a separate patch?
--
Kees Cook
next prev parent reply other threads:[~2022-04-29 22:43 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-29 2:31 [PATCH v3 0/2] Handle seccomp notification preemption Sargun Dhillon
2022-04-29 2:31 ` [PATCH v3 1/2] seccomp: Add wait_killable semantic to seccomp user notifier Sargun Dhillon
2022-04-29 9:42 ` Rodrigo Campos
2022-04-29 17:14 ` Sargun Dhillon
2022-04-29 18:20 ` Kees Cook
2022-05-02 12:48 ` Rodrigo Campos
2022-04-29 18:22 ` Kees Cook
2022-05-02 14:15 ` Rodrigo Campos
2022-05-02 16:04 ` Sargun Dhillon
2022-05-03 14:27 ` Rodrigo Campos
2022-04-29 2:31 ` [PATCH v3 2/2] selftests/seccomp: Add test for wait killable notifier Sargun Dhillon
2022-04-29 18:19 ` Kees Cook
2022-04-29 22:35 ` Sargun Dhillon
2022-04-29 22:43 ` Kees Cook [this message]
2022-04-29 9:24 ` [PATCH v3 0/2] Handle seccomp notification preemption Rodrigo Campos
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