spicec-x11: Change source of controller socket name, fixing CVE-2010-2792
spicec-x11: Change source of controller socket name, fixing CVE-2010-2792

The socket name used to communicate between the xpi browser plugin and the
spicec was predictable allowing a non priviliged user on the same system
to create the socket before spicec does and thus intercept the messages from
the xpi to the client, including login credentials. This security vulnerability
has been registred with mitre as CVE-2010-2792:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2792

This patch changes the controller code to instead read the socket name
from an environment variable which gets set by the xpi before executing
the spicec, making the socketname private between the client and the xpi.

Note that this means that the controller will only work with an xpi which
has matching changes, the changes are present in the latest version of the
xpi as available as update for / with RHEL-5.5 and RHEL-6.0 .

mathslinux/spice,virtualAMP/spiceplay,freedesktop-unofficial-mirror/spice__spice,mathslinux/spice,alon/spice-server,elmarco/spice,virtualAMP/spiceplay,ya-mouse/spice,fgouget/spice,mathslinux/spice,SPICE/spice,alon/spice-server,elmarco/spice,alon/spice-server,fgouget/spice,dezelin/spice,dezelin/spice,dezelin/spice,mathslinux/spice,virtualAMP/spiceplay,Fantu/spice,elmarco/spice,dezelin/spice,virtualAMP/spiceplay,elmarco/spice,ya-mouse/spice,mathslinux/spice,dezelin/spice,alon/spice-server,Fantu/spice,SPICE/spice,fgouget/spice,freedesktop-unofficial-mirror/spice__spice,fgouget/spice,freedesktop-unofficial-mirror/spice__spice,freedesktop-unofficial-mirror/spice__spice,alon/spice-server,SPICE/spice,elmarco/spice,freedesktop-unofficial-mirror/spice__spice,Fantu/spice,ya-mouse/spice,Fantu/spice