1 /*
2  * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * Based on Rusty Russell's IPv4 NAT code. Development of IPv6 NAT
9  * funded by Astaro.
10  */
11 
12 #include <linux/module.h>
13 #include <linux/netfilter.h>
14 #include <linux/netfilter_ipv6.h>
15 #include <linux/netfilter_ipv6/ip6_tables.h>
16 #include <linux/ipv6.h>
17 #include <net/ipv6.h>
18 
19 #include <net/netfilter/nf_nat.h>
20 #include <net/netfilter/nf_nat_core.h>
21 #include <net/netfilter/nf_nat_l3proto.h>
22 
23 static int __net_init ip6table_nat_table_init(struct net *net);
24 
25 static const struct xt_table nf_nat_ipv6_table = {
26 	.name		= "nat",
27 	.valid_hooks	= (1 << NF_INET_PRE_ROUTING) |
28 			  (1 << NF_INET_POST_ROUTING) |
29 			  (1 << NF_INET_LOCAL_OUT) |
30 			  (1 << NF_INET_LOCAL_IN),
31 	.me		= THIS_MODULE,
32 	.af		= NFPROTO_IPV6,
33 	.table_init	= ip6table_nat_table_init,
34 };
35 
36 static unsigned int ip6table_nat_do_chain(void *priv,
37 					  struct sk_buff *skb,
38 					  const struct nf_hook_state *state,
39 					  struct nf_conn *ct)
40 {
41 	return ip6t_do_table(skb, state, state->net->ipv6.ip6table_nat);
42 }
43 
44 static unsigned int ip6table_nat_fn(void *priv,
45 				    struct sk_buff *skb,
46 				    const struct nf_hook_state *state)
47 {
48 	return nf_nat_ipv6_fn(priv, skb, state, ip6table_nat_do_chain);
49 }
50 
51 static unsigned int ip6table_nat_in(void *priv,
52 				    struct sk_buff *skb,
53 				    const struct nf_hook_state *state)
54 {
55 	return nf_nat_ipv6_in(priv, skb, state, ip6table_nat_do_chain);
56 }
57 
58 static unsigned int ip6table_nat_out(void *priv,
59 				     struct sk_buff *skb,
60 				     const struct nf_hook_state *state)
61 {
62 	return nf_nat_ipv6_out(priv, skb, state, ip6table_nat_do_chain);
63 }
64 
65 static unsigned int ip6table_nat_local_fn(void *priv,
66 					  struct sk_buff *skb,
67 					  const struct nf_hook_state *state)
68 {
69 	return nf_nat_ipv6_local_fn(priv, skb, state, ip6table_nat_do_chain);
70 }
71 
72 static const struct nf_hook_ops nf_nat_ipv6_ops[] = {
73 	/* Before packet filtering, change destination */
74 	{
75 		.hook		= ip6table_nat_in,
76 		.pf		= NFPROTO_IPV6,
77 		.nat_hook	= true,
78 		.hooknum	= NF_INET_PRE_ROUTING,
79 		.priority	= NF_IP6_PRI_NAT_DST,
80 	},
81 	/* After packet filtering, change source */
82 	{
83 		.hook		= ip6table_nat_out,
84 		.pf		= NFPROTO_IPV6,
85 		.nat_hook	= true,
86 		.hooknum	= NF_INET_POST_ROUTING,
87 		.priority	= NF_IP6_PRI_NAT_SRC,
88 	},
89 	/* Before packet filtering, change destination */
90 	{
91 		.hook		= ip6table_nat_local_fn,
92 		.pf		= NFPROTO_IPV6,
93 		.nat_hook	= true,
94 		.hooknum	= NF_INET_LOCAL_OUT,
95 		.priority	= NF_IP6_PRI_NAT_DST,
96 	},
97 	/* After packet filtering, change source */
98 	{
99 		.hook		= ip6table_nat_fn,
100 		.nat_hook	= true,
101 		.pf		= NFPROTO_IPV6,
102 		.hooknum	= NF_INET_LOCAL_IN,
103 		.priority	= NF_IP6_PRI_NAT_SRC,
104 	},
105 };
106 
107 static int __net_init ip6table_nat_table_init(struct net *net)
108 {
109 	struct ip6t_replace *repl;
110 	int ret;
111 
112 	if (net->ipv6.ip6table_nat)
113 		return 0;
114 
115 	repl = ip6t_alloc_initial_table(&nf_nat_ipv6_table);
116 	if (repl == NULL)
117 		return -ENOMEM;
118 	ret = ip6t_register_table(net, &nf_nat_ipv6_table, repl,
119 				  nf_nat_ipv6_ops, &net->ipv6.ip6table_nat);
120 	kfree(repl);
121 	return ret;
122 }
123 
124 static void __net_exit ip6table_nat_net_exit(struct net *net)
125 {
126 	if (!net->ipv6.ip6table_nat)
127 		return;
128 	ip6t_unregister_table(net, net->ipv6.ip6table_nat, nf_nat_ipv6_ops);
129 	net->ipv6.ip6table_nat = NULL;
130 }
131 
132 static struct pernet_operations ip6table_nat_net_ops = {
133 	.exit	= ip6table_nat_net_exit,
134 };
135 
136 static int __init ip6table_nat_init(void)
137 {
138 	int ret = register_pernet_subsys(&ip6table_nat_net_ops);
139 
140 	if (ret)
141 		return ret;
142 
143 	ret = ip6table_nat_table_init(&init_net);
144 	if (ret)
145 		unregister_pernet_subsys(&ip6table_nat_net_ops);
146 	return ret;
147 }
148 
149 static void __exit ip6table_nat_exit(void)
150 {
151 	unregister_pernet_subsys(&ip6table_nat_net_ops);
152 }
153 
154 module_init(ip6table_nat_init);
155 module_exit(ip6table_nat_exit);
156 
157 MODULE_LICENSE("GPL");
158