netfilter: Pass struct net into the netfilter hooks

Pass a network namespace parameter into the netfilter hooks.  At the
call site of the netfilter hooks the path a packet is taking through
the network stack is well known which allows the network namespace to
be easily and reliabily.

This allows the replacement of magic code like
"dev_net(state->in?:state->out)" that appears at the start of most
netfilter hooks with "state->net".

In almost all cases the network namespace passed in is derived
from the first network device passed in, guaranteeing those
paths will not see any changes in practice.

The exceptions are:
xfrm/xfrm_output.c:xfrm_output_resume()         xs_net(skb_dst(skb)->xfrm)
ipvs/ip_vs_xmit.c:ip_vs_nat_send_or_cont()      ip_vs_conn_net(cp)
ipvs/ip_vs_xmit.c:ip_vs_send_or_cont()          ip_vs_conn_net(cp)
ipv4/raw.c:raw_send_hdrinc()                    sock_net(sk)
ipv6/ip6_output.c:ip6_xmit()			sock_net(sk)
ipv6/ndisc.c:ndisc_send_skb()                   dev_net(skb->dev) not dev_net(dst->dev)
ipv6/raw.c:raw6_send_hdrinc()                   sock_net(sk)
br_netfilter_hooks.c:br_nf_pre_routing_finish() dev_net(skb->dev) before skb->dev is set to nf_bridge->physindev

In all cases these exceptions seem to be a better expression for the
network namespace the packet is being processed in then the historic
"dev_net(in?in:out)".  I am documenting them in case something odd
pops up and someone starts trying to track down what happened.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 3 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 5b3f2841acf6..124338a39e29 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1645,7 +1645,7 @@ static void mld_sendpack(struct sk_buff *skb)
 	payload_len = skb->len;
 
 	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
-		      net->ipv6.igmp_sk, skb, NULL, skb->dev,
+		      net, net->ipv6.igmp_sk, skb, NULL, skb->dev,
 		      dst_output);
 out:
 	if (!err) {
@@ -2008,8 +2008,9 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type)
 	}
 
 	skb_dst_set(skb, dst);
-	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, sk, skb,
-		      NULL, skb->dev, dst_output);
+	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
+		      net, sk, skb, NULL, skb->dev,
+		      dst_output);
 out:
 	if (!err) {
 		ICMP6MSGOUT_INC_STATS(net, idev, type);