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/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 4c48227..71969de 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1261,6 +1261,10 @@
  *	audit_rule_init.
  *	@rule contains the allocated rule
  *
+ * @inode_invalidate_secctx:
+ *	Notify the security module that it must revalidate the security context
+ *	of an inode.
+ *
  * @inode_notifysecctx:
  *	Notify the security module of what the security context of an inode
  *	should be.  Initializes the incore security context managed by the
@@ -1516,6 +1520,7 @@
 	int (*secctx_to_secid)(const char *secdata, u32 seclen, u32 *secid);
 	void (*release_secctx)(char *secdata, u32 seclen);
 
+	void (*inode_invalidate_secctx)(struct inode *inode);
 	int (*inode_notifysecctx)(struct inode *inode, void *ctx, u32 ctxlen);
 	int (*inode_setsecctx)(struct dentry *dentry, void *ctx, u32 ctxlen);
 	int (*inode_getsecctx)(struct inode *inode, void **ctx, u32 *ctxlen);
@@ -1757,6 +1762,7 @@
 	struct list_head secid_to_secctx;
 	struct list_head secctx_to_secid;
 	struct list_head release_secctx;
+	struct list_head inode_invalidate_secctx;
 	struct list_head inode_notifysecctx;
 	struct list_head inode_setsecctx;
 	struct list_head inode_getsecctx;