openssh: Update to 7.3p1

openssh: Update to 7.3p1

Includes various security fixes:

 * sshd(8): Mitigate a potential denial-of-service attack against
   the system's crypt(3) function via sshd(8). An attacker could
   send very long passwords that would cause excessive CPU use in
   crypt(3). sshd(8) now refuses to accept password authentication
   requests of length greater than 1024 characters. Independently
   reported by Tomas Kuthan (Oracle), Andres Rojas and Javier Nieto.

 * sshd(8): Mitigate timing differences in password authentication
   that could be used to discern valid from invalid account names
   when long passwords were sent and particular password hashing
   algorithms are in use on the server. CVE-2016-6210, reported by
   EddieEzra.Harari at verint.com

 * ssh(1), sshd(8): Fix observable timing weakness in the CBC padding
   oracle countermeasures. Reported by Jean Paul Degabriele, Kenny
   Paterson, Torben Hansen and Martin Albrecht. Note that CBC ciphers
   are disabled by default and only included for legacy compatibility.

 * ssh(1), sshd(8): Improve operation ordering of MAC verification for
   Encrypt-then-MAC (EtM) mode transport MAC algorithms to verify the
   MAC before decrypting any ciphertext. This removes the possibility
   of timing differences leaking facts about the plaintext, though no
   such leakage has been observed.  Reported by Jean Paul Degabriele,
   Kenny Paterson, Torben Hansen and Martin Albrecht.

 * sshd(8): (portable only) Ignore PAM environment vars when
   UseLogin=yes. If PAM is configured to read user-specified
   environment variables and UseLogin=yes in sshd_config, then a
   hostile local user may attack /bin/login via LD_PRELOAD or
   similar environment variables set via PAM. CVE-2015-8325,
   found by Shayan Sadigh.

Fixes: #11160
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>