With the existing pkcheck (pid, start time) tuple for identifying
the process, there is a race condition, where a process can make
a libvirt RPC call and in another thread exec a setuid application,
causing it to change to effective UID 0. This in turn causes polkit
to do its permission check based on the wrong UID.

To address this, libvirt must get the UID the caller had at time
of connect() (from SO_PEERCRED) and pass a (pid, start time, uid)
triple to the pkcheck program.

This fix requires that libvirt is re-built against a version of
polkit that has the fix for its CVE-2013-4288, so that libvirt
can see 'pkg-config --variable pkcheck_supports_uid polkit-gobject-1'
Signed-off-by: NColin Walters <walters@redhat.com>
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

The polkit access driver used the wrong permission names for checks
on storage pools, volumes and node devices. This led to them always
being denied access.

The 'dettach' permission was also mis-spelt and should have been
'detach'. While permission names are ABI sensitive, the fact that
the code used the wrong object name for checking node device
permissions, means that no one could have used the mis-spelt
'dettach' permission.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Add an access control driver that uses the pkcheck command
to check authorization requests. This is fairly inefficient,
particularly for cases where an API returns a list of objects
and needs to check permission for each object.

It would be desirable to use the polkit API but this links
to glib with abort-on-OOM behaviour, so can't be used. The
other alternative is to speak to dbus directly
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>