[NETFILTER]: Fix connection tracking bug in 2.6.12

In 2.6.12 we started dropping the conntrack reference when a packet
leaves the IP layer. This broke connection tracking on a bridge,
because bridge-netfilter defers calling some NF_IP_* hooks to the bridge
layer for locally generated packets going out a bridge, where the
conntrack reference is no longer available. This patch keeps the
reference in this case as a temporary solution, long term we will
remove the defered hook calling. No attempt is made to drop the
reference in the bridge-code when it is no longer needed, tc actions
could already have sent the packet anywhere.

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

net/bridge/br_netfilter.c

@@ -844,7 +844,7 @@ static unsigned int ip_sabotage_out(unsigned int hook, struct sk_buff **pskb,
 		 * doesn't use the bridge parent of the indev by using
 		 * the BRNF_DONT_TAKE_PARENT mask. */
 		if (hook == NF_IP_FORWARD && nf_bridge->physindev == NULL) {
-			nf_bridge->mask &= BRNF_DONT_TAKE_PARENT;
+			nf_bridge->mask |= BRNF_DONT_TAKE_PARENT;
 			nf_bridge->physindev = (struct net_device *)in;
 		}
 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)

net/ipv4/ip_output.c

@@ -188,7 +188,13 @@ static inline int ip_finish_output2(struct sk_buff *skb)
 		skb = skb2;
 	}
 
-	nf_reset(skb);
+#ifdef CONFIG_BRIDGE_NETFILTER
+	/* bridge-netfilter defers calling some IP hooks to the bridge layer
+	 * and still needs the conntrack reference.
+	 */
+	if (skb->nf_bridge == NULL)
+#endif
+		nf_reset(skb);
 
 	if (hh) {
 		int hh_alen;