diff options
authorPatrick McHardy <kaber@trash.net>2008-01-11 18:02:18 -0800
committerDavid S. Miller <davem@davemloft.net>2008-01-11 18:02:18 -0800
commit2948d2ebbb98747b912ac6d0c864b4d02be8a6f5 (patch)
parent[NETFILTER]: xt_helper: Do not bypass RCU (diff)
[NETFILTER]: bridge: fix double POST_ROUTING invocation
The bridge code incorrectly causes two POST_ROUTING hook invocations for DNATed packets that end up on the same bridge device. This happens because packets with a changed destination address are passed to dst_output() to make them go through the neighbour output function again to build a new destination MAC address, before they will continue through the IP hooks simulated by bridge netfilter. The resulting hook order is: PREROUTING (bridge netfilter) POSTROUTING (dst_output -> ip_output) FORWARD (bridge netfilter) POSTROUTING (bridge netfilter) The deferred hooks used to abort the first POST_ROUTING invocation, but since the only thing bridge netfilter actually really wants is a new MAC address, we can avoid going through the IP stack completely by simply calling the neighbour output function directly. Tested, reported and lots of data provided by: Damien Thebault <damien.thebault@gmail.com> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
1 files changed, 12 insertions, 6 deletions
diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index c1757c79dfbb..5d8b939eded1 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -247,8 +247,9 @@ static void __br_dnat_complain(void)
* Let us first consider the case that ip_route_input() succeeds:
* If skb->dst->dev equals the logical bridge device the packet
- * came in on, we can consider this bridging. We then call
- * skb->dst->output() which will make the packet enter br_nf_local_out()
+ * came in on, we can consider this bridging. The packet is passed
+ * through the neighbour output function to build a new destination
+ * MAC address, which will make the packet enter br_nf_local_out()
* not much later. In that function it is assured that the iptables
* FORWARD chain is traversed for the packet.
@@ -285,12 +286,17 @@ static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
skb->dev = bridge_parent(skb->dev);
- if (!skb->dev)
- kfree_skb(skb);
- else {
+ if (skb->dev) {
+ struct dst_entry *dst = skb->dst;
- skb->dst->output(skb);
+ if (dst->hh)
+ return neigh_hh_output(dst->hh, skb);
+ else if (dst->neighbour)
+ return dst->neighbour->output(skb);
+ kfree_skb(skb);
return 0;