Previously we would decode state directly into our current ticket_handler.
This is problematic if for some reason we fail to decode, because we end
up with half new state and half old state.

We are probably already in bad shape if we get an update we can't decode,
but we may as well be tidy anyway.  Decode into new_* temporaries and
update the ticket_handler only on success.
Signed-off-by: NSage Weil <sage@newdream.net>

Release the old ticket_blob buffer when we get an updated service ticket
from the monitor.  Previously these were getting leaked.
Signed-off-by: NSage Weil <sage@newdream.net>

The buffer size was incorrectly calculated for the ceph_x_encrypt()
encapsulated ticket blob.  Use a helper (with correct arithmetic) and
BUG out if we were wrong.
Signed-off-by: NSage Weil <sage@newdream.net>

The auth_x protocol implements support for a kerberos-like mutual
authentication infrastructure used by Ceph.  We do not simply use vanilla
kerberos because of scalability and performance issues when dealing with
a large cluster of nodes providing a single logical service.

Auth_x provides mutual authentication of client and server and protects
against replay and man in the middle attacks.  It does not encrypt
the full session over the wire, however, so data payload may still be
snooped.
Signed-off-by: NYehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: NSage Weil <sage@newdream.net>