security: Add hook to invalidate inode security labels

Add a hook to invalidate an inode's security label when the cached
information becomes invalid.

Add the new hook in selinux: set a flag when a security label becomes
invalid.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <pmoore@redhat.com>
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index 81fa718..a2ae054 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -37,6 +37,12 @@
 	u32 sockcreate_sid;	/* fscreate SID */
 };
 
+enum label_initialized {
+	LABEL_MISSING,		/* not initialized */
+	LABEL_INITIALIZED,	/* inizialized */
+	LABEL_INVALID		/* invalid */
+};
+
 struct inode_security_struct {
 	struct inode *inode;	/* back pointer to inode object */
 	union {