selftests/seccomp: Add test for wait killable notifier
This verifies that if a filter is set up with the wait killable feature
that it obeys the semantics that non-fatal signals are ignored during
a notification after the notification is received.
Cases tested:
* Non-fatal signal prior to receive
* Non-fatal signal during receive
* Fatal signal after receive
The normal signal handling is tested in user_notification_signal. That
behaviour remains unchanged.
On an unsupported kernel, these tests will immediately bail as it relies
on a new seccomp flag.
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220503080958.20220-4-sargun@sargun.me