ntp: import RedHat patch to fix CVE-2014-9293

If no auth key is set in the configuration file, ntpd would generate
a random key on the fly. There were two problems with this: 1) the
generated key was 31 bits in size, and 2) it used the (now weak)
ntp_random() function, which was seeded with a 32 bit value and can
only provide 32 bits of entropy. This was sufficient back in the late
1990s when this code was written. Not today.

This vulnerability was discovered in ntp-4.2.6 by Neel Mehta of the
Google Security Team.

Bug #418 http://bugzilla.vyos.net/show_bug.cgi?id=418
ntp: import RedHat patch to fix CVE-2014-9294

Prior to ntp-4.2.7p230 ntp-keygen used a weak seed to prepare a random
number generator that was of good quality back in the late 1990s. The
random numbers produced was then used to generate symmetric keys. In
ntp-4.2.8 we use a current-technology cryptographic random number
generator, either RAND_bytes from OpenSSL, or arc4random().

This vulnerability was discovered in ntp-4.2.6 by Stephen Roettger
of the Google Security Team.

Bug #419 http://bugzilla.vyos.net/show_bug.cgi?id=419
ntp: import RedHat patch to fix CVE-2014-9295

When Autokey Authentication is enabled (i.e. the ntp.conf file contains
a crypto pw ... directive) a remote attacker can send a carefully
crafted packet that can overflow a stack buffer and potentially allow
malicious code to be executed with the privilege level of the ntpd
process.

A remote attacker can send a carefully crafted packet that can overflow
a stack buffer and potentially allow malicious code to be executed with
the privilege level of the ntpd process.

This vulnerability was discovered by Stephen Roettger of the Google
Security Team.

Bug #420 http://bugzilla.vyos.net/show_bug.cgi?id=420
ntp: import RedHat patch to fix CVE-2014-9296

Code in ntp_proto.c:receive() is missing a return; in the code path
where an error was detected, which meant processing did not stop when a
specific rare error occurred. We haven't found a way for this bug to
affect system integrity. If there is no way to affect system integrity
the base CVSS score for this bug is 0. If there is one avenue through
which system integrity can be partially affected, the base score
becomes a 5. If system integrity can be partially affected via all
three integrity metrics, the CVSS base score become 7.5.

This vulnerability was discovered by Stephen Roettger of the Google
Security Team.

Bug #421 http://bugzilla.vyos.net/show_bug.cgi?id=421