[NETFILTER]: Redo policy lookups after NAT when neccessary

When NAT changes the key used for the xfrm lookup it needs to be done
again. If a new policy is returned in POST_ROUTING the packet needs
to be passed to xfrm4_output_one manually after all hooks were called
because POST_ROUTING is called with fixed okfn (ip_finish_output).

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 8b1c9bd0091e..59fdac3a099a 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -202,6 +202,11 @@ static inline int ip_finish_output2(struct sk_buff *skb)
 
 static inline int ip_finish_output(struct sk_buff *skb)
 {
+#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
+        /* Policy lookup after SNAT yielded a new policy */
+        if (skb->dst->xfrm != NULL)
+                return xfrm4_output_finish(skb);
+#endif
         if (skb->len > dst_mtu(skb->dst) &&
             !(skb_shinfo(skb)->ufo_size || skb_shinfo(skb)->tso_size))
                 return ip_fragment(skb, ip_finish_output2);