xfrm: force a garbage collection after deleting a policy

In some cases after deleting a policy from the SPD the policy would
remain in the dst/flow/route cache for an extended period of time
which caused problems for SELinux as its dynamic network access
controls key off of the number of XFRM policy and state entries.
This patch corrects this problem by forcing a XFRM garbage collection
whenever a policy is sucessfully removed.
Reported-by: Ondrej Moris <omoris@redhat.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/xfrm.h

@@ -1160,6 +1160,8 @@ static inline void xfrm_sk_free_policy(struct sock *sk)
 	}
 }
 
+extern void xfrm_garbage_collect(struct net *net);
+
 #else
 
 static inline void xfrm_sk_free_policy(struct sock *sk) {}
@@ -1194,6 +1196,9 @@ static inline int xfrm6_policy_check_reverse(struct sock *sk, int dir,
 {
 	return 1;
 }
+static inline void xfrm_garbage_collect(struct net *net)
+{
+}
 #endif
 
 static __inline__

net/key/af_key.c

@@ -2366,6 +2366,8 @@ static int pfkey_spddelete(struct sock *sk, struct sk_buff *skb, const struct sa
 
 out:
 	xfrm_pol_put(xp);
+	if (err == 0)
+		xfrm_garbage_collect(net);
 	return err;
 }
 
@@ -2615,6 +2617,8 @@ static int pfkey_spdget(struct sock *sk, struct sk_buff *skb, const struct sadb_
 
 out:
 	xfrm_pol_put(xp);
+	if (delete && err == 0)
+		xfrm_garbage_collect(net);
 	return err;
 }
 

net/xfrm/xfrm_policy.c

@@ -2557,11 +2557,12 @@ static void __xfrm_garbage_collect(struct net *net)
 	}
 }
 
-static void xfrm_garbage_collect(struct net *net)
+void xfrm_garbage_collect(struct net *net)
 {
 	flow_cache_flush();
 	__xfrm_garbage_collect(net);
 }
+EXPORT_SYMBOL(xfrm_garbage_collect);
 
 static void xfrm_garbage_collect_deferred(struct net *net)
 {

net/xfrm/xfrm_user.c

@@ -1681,6 +1681,8 @@ static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 out:
 	xfrm_pol_put(xp);
+	if (delete && err == 0)
+		xfrm_garbage_collect(net);
 	return err;
 }