CVE-2021-20251 s3: Ensure bad password count atomic updates for SAMR AES password...

CVE-2021-20251 s3: Ensure bad password count atomic updates for SAMR AES password change

The bad password count is supposed to limit the number of failed login
attempt a user can make before being temporarily locked out, but race
conditions between processes have allowed determined attackers to make
many more than the specified number of attempts.  This is especially
bad on constrained or overcommitted hardware.

To fix this, once a bad password is detected, we reload the sam account
information under a user-specific mutex, ensuring we have an up to
date bad password count.

We also update the bad password count if the password is wrong, which we
did not previously do.

Derived from a similar patch to source3/auth/check_samsec.c by
Jeremy Allison <jra@samba.org>

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14611

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Tue Sep 13 00:08:07 UTC 2022 on sn-devel-184