[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/linux/netfilter/x_tables.h

@@ -335,7 +335,8 @@ extern int xt_check_target(const struct xt_target *target, unsigned short family
 			   unsigned int size, const char *table, unsigned int hook,
 			   unsigned short proto, int inv_proto);
 
-extern struct xt_table *xt_register_table(struct xt_table *table,
+extern struct xt_table *xt_register_table(struct net *net,
+					  struct xt_table *table,
 					  struct xt_table_info *bootstrap,
 					  struct xt_table_info *newinfo);
 extern void *xt_unregister_table(struct xt_table *table);
@@ -352,7 +353,8 @@ extern struct xt_target *xt_request_find_target(int af, const char *name,
 extern int xt_find_revision(int af, const char *name, u8 revision, int target,
 			    int *err);
 
-extern struct xt_table *xt_find_table_lock(int af, const char *name);
+extern struct xt_table *xt_find_table_lock(struct net *net, int af,
+					   const char *name);
 extern void xt_table_unlock(struct xt_table *t);
 
 extern int xt_proto_init(int af);

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

include/net/netns/x_tables.h

@@ -0,0 +1,10 @@
+#ifndef __NETNS_X_TABLES_H
+#define __NETNS_X_TABLES_H
+
+#include <linux/list.h>
+#include <linux/net.h>
+
+struct netns_xt {
+	struct list_head tables[NPROTO];
+};
+#endif