Merge branch 'xfrm: state: exact mark/mask match for control-plane SA lookups'

Antony Antony says:

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While looking into a XFRM_MSG_MIGRATE_STATE issue reported by Sashiko,
we found the underlying problem generalizes: xfrm allows multiple SAs
to coexist for the same (SPI, daddr, proto) differing only in mark,
and every netlink method that resolves "which SA" - xfrm get_sa(),
del_sa(), update, get_ae, new_ae, expire, migrate - uses the same
wildcard mark match the data path needs. A broader-mask SA can
silently shadow a more specific one:

  # ip xfrm state add ... spi 0x1000 mark 1 mask 1 (SA_target)
  # ip xfrm state add ... spi 0x1000 mark 0 mask 0
    (SA_decoy, catch-all, added after -> bucket head)
  # ip xfrm state delete dst ... proto esp spi 0x1000 mark 1 mask 1
    -> deletes SA_decoy; SA_target survives, untouched

xfrm policy had the same bug, fixed in commit 4f47e8ab6ab7
("xfrm: policy: match with both mark and mask on user interfaces").

Netlink state lookups using spi use an exact mark/mask match except
for UPDSA; the wildcard match stays for the data path and state_add only.
This series applies that fix across every affected method,
not just XFRM_MSG_MIGRATE_STATE.

Also reject marks with value bits outside the mask (state ADD,
ALLOCSPI, policy ADD, MIGRATE_STATE new mark). These are
misconfigurations anyway, since the extra bits can never match, and
break exact match added here.

This series does not touch PF_KEY, which no longer receives
non-critical fixes.

state_lookup_byaddr is out of scope. This is only fixing spi based
lookups.
====================

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>