kdc: update PAC hooks for Samba
Samba includes the user's long-term credentials (encrypted in the AS reply key)
to allow legacy authentication protocols such as NTLM to work even if the
pre-authentication mechanism replaced the reply key (as PKINIT does).
Samba also needs to know whether the client explicitly requested a PAC be
included (or excluded), in order to defer PAC exclusion until a service ticket
is issued (thereby avoiding a name binding attack if the user is renamed
between TGT and service ticket issuance).
References:
https://bugzilla.samba.org/show_bug.cgi?id=11441
https://bugzilla.samba.org/show_bug.cgi?id=14561
Closes: #864
Original authors:
- Joseph Sutton <josephsutton@catalyst.net.nz>
- Andrew Bartlett <abartlet@samba.org>
- Stefan Metzmacher <metze@samba.org>