ipv4: Pass struct net into ip_defrag and ip_check_defrag

The function ip_defrag is called on both the input and the output
paths of the networking stack.  In particular conntrack when it is
tracking outbound packets from the local machine calls ip_defrag.

So add a struct net parameter and stop making ip_defrag guess which
network namespace it needs to defragment packets in.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 804b86f..b1209b6 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -170,7 +170,7 @@
 		     sk->sk_bound_dev_if == dev->ifindex) &&
 		    net_eq(sock_net(sk), net)) {
 			if (ip_is_fragment(ip_hdr(skb))) {
-				if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
+				if (ip_defrag(net, skb, IP_DEFRAG_CALL_RA_CHAIN))
 					return true;
 			}
 			if (last) {
@@ -247,14 +247,15 @@
 	/*
 	 *	Reassemble IP fragments.
 	 */
+	struct net *net = dev_net(skb->dev);
 
 	if (ip_is_fragment(ip_hdr(skb))) {
-		if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
+		if (ip_defrag(net, skb, IP_DEFRAG_LOCAL_DELIVER))
 			return 0;
 	}
 
 	return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN,
-		       dev_net(skb->dev), NULL, skb, skb->dev, NULL,
+		       net, NULL, skb, skb->dev, NULL,
 		       ip_local_deliver_finish);
 }