Merge branch 'tcp-ao-fixes'

Dmitry Safonov says:

====================
TCP-AO fixes

Changes from v4:
- Dropped 2 patches on which there's no consensus. They will require
  more work TBD if they may made acceptable. Those are:
  o "net/tcp: Allow removing current/rnext TCP-AO keys on TCP_LISTEN sockets"
  o "net/tcp: Store SNEs + SEQs on ao_info"

Changes from v3:
- Don't restrict adding any keys on TCP-AO connection in VRF, but only
  the ones that don't match l3index (David)

Changes from v2:
- rwlocks are problematic in net code (Paolo)
  Changed the SNE code to avoid spin/rw locks on RX/TX fastpath by
  double-accounting SEQ numbers for TCP-AO enabled connections.

Changes from v1:
- Use tcp_can_repair_sock() helper to limit TCP_AO_REPAIR (Eric)
- Instead of hook to listen() syscall, allow removing current/rnext keys
  on TCP_LISTEN (addressing Eric's objection)
- Add sne_lock to protect snd_sne/rcv_sne
- Don't move used_tcp_ao in struct tcp_request_sock (Eric)

I've been working on TCP-AO key-rotation selftests and as a result
exercised some corner-cases that are not usually met in production.

Here are a bunch of semi-related fixes:
- Documentation typo (reported by Markus Elfring)
- Proper alignment for TCP-AO option in TCP header that has MAC length
  of non 4 bytes (now a selftest with randomized maclen/algorithm/etc
  passes)
- 3 uAPI restricting patches that disallow more things to userspace in
  order to prevent it shooting itself in any parts of the body
- SNEs READ_ONCE()/WRITE_ONCE() that went missing by my human factor
- Avoid storing MAC length from SYN header as SYN-ACK will use
  rnext_key.maclen (drops an extra check that fails on new selftests)
====================

Link: https://lore.kernel.org/r/
Signed-off-by: Paolo Abeni <pabeni@redhat.com>