[NETFILTER]: x_tables: per-netns xt_tables

In fact all we want is per-netns set of rules, however doing that will
unnecessary complicate routines such as ipt_hook()/ipt_do_table, so
make full xt_table array per-netns.

Every user stubbed with init_net for a while.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/net_namespace.h

@@ -12,6 +12,7 @@
 #include <net/netns/packet.h>
 #include <net/netns/ipv4.h>
 #include <net/netns/ipv6.h>
+#include <net/netns/x_tables.h>
 
 struct proc_dir_entry;
 struct net_device;
@@ -56,6 +57,9 @@ struct net {
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 	struct netns_ipv6	ipv6;
 #endif
+#ifdef CONFIG_NETFILTER
+	struct netns_xt		xt;
+#endif
 };
 
 #ifdef CONFIG_NET