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, 8 insertions, 7 deletions

diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index c1127908e23a..7886c9d7e23d 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -394,7 +394,7 @@ bridged_dnat:
 				nf_bridge_push_encap_header(skb);
 				NF_HOOK_THRESH(NFPROTO_BRIDGE,
 					       NF_BR_PRE_ROUTING,
-					       sk, skb, skb->dev, NULL,
+					       net, sk, skb, skb->dev, NULL,
 					       br_nf_pre_routing_finish_bridge,
 					       1);
 				return 0;
@@ -414,7 +414,7 @@ bridged_dnat:
 	skb->dev = nf_bridge->physindev;
 	nf_bridge_update_protocol(skb);
 	nf_bridge_push_encap_header(skb);
-	NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, sk, skb,
+	NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, net, sk, skb,
 		       skb->dev, NULL,
 		       br_handle_frame_finish, 1);
 
@@ -512,7 +512,7 @@ static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
 
 	skb->protocol = htons(ETH_P_IP);
 
-	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->sk, skb,
+	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
 		skb->dev, NULL,
 		br_nf_pre_routing_finish);
 
@@ -539,6 +539,7 @@ static unsigned int br_nf_local_in(const struct nf_hook_ops *ops,
 static int br_nf_forward_finish(struct sock *sk, struct sk_buff *skb)
 {
 	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
+	struct net *net = dev_net(skb->dev);
 	struct net_device *in;
 
 	if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
@@ -560,7 +561,7 @@ static int br_nf_forward_finish(struct sock *sk, struct sk_buff *skb)
 	}
 	nf_bridge_push_encap_header(skb);
 
-	NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, sk, skb,
+	NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, net, sk, skb,
 		       in, skb->dev, br_forward_finish, 1);
 	return 0;
 }
@@ -627,7 +628,7 @@ static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
 	else
 		skb->protocol = htons(ETH_P_IPV6);
 
-	NF_HOOK(pf, NF_INET_FORWARD, NULL, skb,
+	NF_HOOK(pf, NF_INET_FORWARD, state->net, NULL, skb,
 		brnf_get_logical_dev(skb, state->in),
 		parent,	br_nf_forward_finish);
 
@@ -662,7 +663,7 @@ static unsigned int br_nf_forward_arp(const struct nf_hook_ops *ops,
 		return NF_ACCEPT;
 	}
 	*d = state->in;
-	NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->sk, skb,
+	NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->net, state->sk, skb,
 		state->in, state->out, br_nf_forward_finish);
 
 	return NF_STOLEN;
@@ -842,7 +843,7 @@ static unsigned int br_nf_post_routing(const struct nf_hook_ops *ops,
 	else
 		skb->protocol = htons(ETH_P_IPV6);
 
-	NF_HOOK(pf, NF_INET_POST_ROUTING, state->sk, skb,
+	NF_HOOK(pf, NF_INET_POST_ROUTING, state->net, state->sk, skb,
 		NULL, realoutdev,
 		br_nf_dev_queue_xmit);