selinux: fix avdcache auditing

selinux: fix avdcache auditing

The per-task avdcache was incorrectly saving and reusing the
audited vector computed by avc_audit_required() rather than
recomputing based on the currently requested permissions and
distinguishing the denied versus allowed cases. As a result,
some permission checks were not being audited, e.g.
directory write checks after a previously cached directory
search check.

Cc: stable@vger.kernel.org
Fixes: dde3a5d0f4dce ("selinux: move avdcache to per-task security struct")
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
[PM: line wrap tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>