[PATCH 3/4] seccomp: Add SECCOMP_USER_NOTIF_FLAG_PIDFD to get pidfd on listener trap

[Sargun Dhillon]

On Fri, Jan 24, 2020 at 10:03 AM Tycho Andersen <tycho at tycho.ws> wrote:
>
> On Fri, Jan 24, 2020 at 01:17:42AM -0800, Sargun Dhillon wrote:
> > Currently, this just opens the group leader of the thread that triggere
> > the event, as pidfds (currently) are limited to group leaders.
>
> I don't love the semantics of this; when they're not limited to thread
> group leaders any more, we won't be able to change this. Is that work
> far off?
>
> Tycho

We would be able to change this in the future if we introduced a flag like
SECCOMP_USER_NOTIF_FLAG_PIDFD_THREAD which would send a
pidfd that's for the thread, and not just the group leader. The flag could
either be XOR with SECCOMP_USER_NOTIF_FLAG_PIDFD, or
could require both. Alternatively, we can rename
SECCOMP_USER_NOTIF_FLAG_PIDFD to
SECCOMP_USER_NOTIF_FLAG_GROUP_LEADER_PIDFD.