Re: [PATCH v4 00/10] net: support thread-specific pidfds for send and connect

On Mon, Oct 12, 2026 at 05:59:17PM +0200, Paolo Abeni wrote:

On 10/5/26 17:09, Andrew Halaney wrote:

quoted

SO_PASSPIDFD/SCM_PIDFD and SO_PEERPIDFD allow to retrieve a pidfd for
the thread-group leader. The coredump server using the coredump socket
cannot get a handle on the task that took the signal and is writing the
coredump easily. Workloads interested in per-thread authentification
have similar problems.

Add SO_PASSPIDFD_THREAD/SCM_PIDFD_THREAD and SO_PEERPIDFD_THREAD. We
record the sending and the connecting thread in addition to the
thread-group leader.

SO_PASSPIDFD_THREAD functions like SO_PASSPIDFD but instead of an
SCM_PIDFD message for the thread-group leader, SCM_PIDFD_THREAD sends a
pidfd for the specific thread. SO_PASSPIDFD / SO_PASSPIDFD_THREAD are
independent, allowing callers to get both styles of pidfd back in their
cmsg.

SO_PEERPIDFD_THREAD allows to retrieve a pidfd for the specific thread
that called connect(), listen(), or socketpair().

pidfs_coredump() now also stamps the dumping thread's struct pid so a
pidfd for that thread reports the coredump like the pidfd of the
thread-group leader does.

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Signed-off-by: Andrew Halaney <redacted>

---
Changes in v4:
- Moved get_pid() out of scm_set_cred() into scm_send() (Kuniyuki)
- Dropped unnecessary helps (Kuniyuki)
- Rebased on v7.3-r6
- Collected Kuniyuki's RB tags
- Link to v3: https://lore.kernel.org/r/20260928-work-unix-passpidfd-v3-0-532018a91b21@amutable.com (local)

Out of sheer ignorance, I don't see the shared, stable tree where we
can pull from, can you please point that out?

Here ya go!

https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git/log/?h=vfs-7.4.shared.net-next.pidfd

I think that this late in the cycle, the series could go via Christian's
tree only and we could get it back after the merge window. WDYT?

This works for me at least, for what its worth.

Thanks,
Andrew