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, 12 insertions, 15 deletions

diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index 042148dc1e22..295f2650b5dc 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -190,12 +190,11 @@ static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 	return 1;
 }
 
-static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sock *sk,
-			  struct sk_buff *skb, struct net_device *indev,
-			  struct net_device *outdev,
+static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
+			  struct sock *sk, struct sk_buff *skb,
+			  struct net_device *indev, struct net_device *outdev,
 			  int (*okfn)(struct sock *, struct sk_buff *))
 {
-	struct net *net = dev_net(indev ? indev : outdev);
 	return nf_hook_thresh(pf, hook, net, sk, skb, indev, outdev, okfn, INT_MIN);
 }
                    
@@ -217,12 +216,11 @@ static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sock *sk,
 */
 
 static inline int
-NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sock *sk,
+NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 	       struct sk_buff *skb, struct net_device *in,
 	       struct net_device *out,
 	       int (*okfn)(struct sock *, struct sk_buff *), int thresh)
 {
-	struct net *net = dev_net(in ? in : out);
 	int ret = nf_hook_thresh(pf, hook, net, sk, skb, in, out, okfn, thresh);
 	if (ret == 1)
 		ret = okfn(sk, skb);
@@ -230,11 +228,10 @@ NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sock *sk,
 }
 
 static inline int
-NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sock *sk,
+NF_HOOK_COND(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 	     struct sk_buff *skb, struct net_device *in, struct net_device *out,
 	     int (*okfn)(struct sock *, struct sk_buff *), bool cond)
 {
-	struct net *net = dev_net(in ? in : out);
 	int ret;
 
 	if (!cond ||
@@ -244,11 +241,11 @@ NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sock *sk,
 }
 
 static inline int
-NF_HOOK(uint8_t pf, unsigned int hook, struct sock *sk, struct sk_buff *skb,
+NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, struct sk_buff *skb,
 	struct net_device *in, struct net_device *out,
 	int (*okfn)(struct sock *, struct sk_buff *))
 {
-	return NF_HOOK_THRESH(pf, hook, sk, skb, in, out, okfn, INT_MIN);
+	return NF_HOOK_THRESH(pf, hook, net, sk, skb, in, out, okfn, INT_MIN);
 }
 
 /* Call setsockopt() */
@@ -348,11 +345,11 @@ nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 }
 
 #else /* !CONFIG_NETFILTER */
-#define NF_HOOK(pf, hook, sk, skb, indev, outdev, okfn) (okfn)(sk, skb)
-#define NF_HOOK_COND(pf, hook, sk, skb, indev, outdev, okfn, cond) (okfn)(sk, skb)
-static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sock *sk,
-			  struct sk_buff *skb, struct net_device *indev,
-			  struct net_device *outdev,
+#define NF_HOOK(pf, hook, net, sk, skb, indev, outdev, okfn) (okfn)(sk, skb)
+#define NF_HOOK_COND(pf, hook, net, sk, skb, indev, outdev, okfn, cond) (okfn)(sk, skb)
+static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
+			  struct sock *sk, struct sk_buff *skb,
+			  struct net_device *indev, struct net_device *outdev,
 			  int (*okfn)(struct sock *, struct sk_buff *))
 {
 	return 1;