netfilter: arptables in netns for real

IN, FORWARD -- grab netns from in device, OUT -- from out device.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/arptable_filter.c

@@ -55,32 +55,53 @@ static struct xt_table packet_filter = {
 };
 
 /* The work comes in here from netfilter.c */
-static unsigned int arpt_hook(unsigned int hook,
+static unsigned int arpt_in_hook(unsigned int hook,
 				 struct sk_buff *skb,
 				 const struct net_device *in,
 				 const struct net_device *out,
 				 int (*okfn)(struct sk_buff *))
 {
-	return arpt_do_table(skb, hook, in, out, init_net.ipv4.arptable_filter);
+	return arpt_do_table(skb, hook, in, out,
+			     dev_net(in)->ipv4.arptable_filter);
+}
+
+static unsigned int arpt_out_hook(unsigned int hook,
+				  struct sk_buff *skb,
+				  const struct net_device *in,
+				  const struct net_device *out,
+				  int (*okfn)(struct sk_buff *))
+{
+	return arpt_do_table(skb, hook, in, out,
+			     dev_net(out)->ipv4.arptable_filter);
+}
+
+static unsigned int arpt_forward_hook(unsigned int hook,
+				      struct sk_buff *skb,
+				      const struct net_device *in,
+				      const struct net_device *out,
+				      int (*okfn)(struct sk_buff *))
+{
+	return arpt_do_table(skb, hook, in, out,
+			     dev_net(in)->ipv4.arptable_filter);
 }
 
 static struct nf_hook_ops arpt_ops[] __read_mostly = {
 	{
-		.hook		= arpt_hook,
+		.hook		= arpt_in_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NF_ARP,
 		.hooknum	= NF_ARP_IN,
 		.priority	= NF_IP_PRI_FILTER,
 	},
 	{
-		.hook		= arpt_hook,
+		.hook		= arpt_out_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NF_ARP,
 		.hooknum	= NF_ARP_OUT,
 		.priority	= NF_IP_PRI_FILTER,
 	},
 	{
-		.hook		= arpt_hook,
+		.hook		= arpt_forward_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NF_ARP,
 		.hooknum	= NF_ARP_FORWARD,