Previously, we were gathering the context instead of the sid. Now in this patch,
we gather just the sid and convert to context only if an audit event is being
output.

This patch brings the performance hit from 146% down to 23%
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The following patch provides selinux interfaces that will allow the audit
system to perform filtering based on the process context (user, role, type,
sensitivity, and clearance).  These interfaces will allow the selinux
module to perform efficient matches based on lower level selinux constructs,
rather than relying on context retrievals and string comparisons within
the audit module.  It also allows for dominance checks on the mls portion
of the contexts that are impossible with only string comparisons.
Signed-off-by: NDarrel Goeddel <dgoeddel@trustedcs.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>