1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
4  *
5  * Based on Rusty Russell's IPv4 NAT code. Development of IPv6 NAT
6  * funded by Astaro.
7  */
8 
9 #include <linux/module.h>
10 #include <linux/netfilter.h>
11 #include <linux/netfilter_ipv6.h>
12 #include <linux/netfilter_ipv6/ip6_tables.h>
13 #include <linux/ipv6.h>
14 #include <net/ipv6.h>
15 
16 #include <net/netfilter/nf_nat.h>
17 
18 struct ip6table_nat_pernet {
19 	struct nf_hook_ops *nf_nat_ops;
20 };
21 
22 static int __net_init ip6table_nat_table_init(struct net *net);
23 
24 static unsigned int ip6table_nat_net_id __read_mostly;
25 
26 static const struct xt_table nf_nat_ipv6_table = {
27 	.name		= "nat",
28 	.valid_hooks	= (1 << NF_INET_PRE_ROUTING) |
29 			  (1 << NF_INET_POST_ROUTING) |
30 			  (1 << NF_INET_LOCAL_OUT) |
31 			  (1 << NF_INET_LOCAL_IN),
32 	.me		= THIS_MODULE,
33 	.af		= NFPROTO_IPV6,
34 	.table_init	= ip6table_nat_table_init,
35 };
36 
37 static unsigned int ip6table_nat_do_chain(void *priv,
38 					  struct sk_buff *skb,
39 					  const struct nf_hook_state *state)
40 {
41 	return ip6t_do_table(skb, state, priv);
42 }
43 
44 static const struct nf_hook_ops nf_nat_ipv6_ops[] = {
45 	{
46 		.hook		= ip6table_nat_do_chain,
47 		.pf		= NFPROTO_IPV6,
48 		.hooknum	= NF_INET_PRE_ROUTING,
49 		.priority	= NF_IP6_PRI_NAT_DST,
50 	},
51 	{
52 		.hook		= ip6table_nat_do_chain,
53 		.pf		= NFPROTO_IPV6,
54 		.hooknum	= NF_INET_POST_ROUTING,
55 		.priority	= NF_IP6_PRI_NAT_SRC,
56 	},
57 	{
58 		.hook		= ip6table_nat_do_chain,
59 		.pf		= NFPROTO_IPV6,
60 		.hooknum	= NF_INET_LOCAL_OUT,
61 		.priority	= NF_IP6_PRI_NAT_DST,
62 	},
63 	{
64 		.hook		= ip6table_nat_do_chain,
65 		.pf		= NFPROTO_IPV6,
66 		.hooknum	= NF_INET_LOCAL_IN,
67 		.priority	= NF_IP6_PRI_NAT_SRC,
68 	},
69 };
70 
71 static int ip6t_nat_register_lookups(struct net *net)
72 {
73 	struct ip6table_nat_pernet *xt_nat_net;
74 	struct nf_hook_ops *ops;
75 	struct xt_table *table;
76 	int i, ret;
77 
78 	table = xt_find_table(net, NFPROTO_IPV6, "nat");
79 	if (WARN_ON_ONCE(!table))
80 		return -ENOENT;
81 
82 	xt_nat_net = net_generic(net, ip6table_nat_net_id);
83 	ops = kmemdup(nf_nat_ipv6_ops, sizeof(nf_nat_ipv6_ops), GFP_KERNEL);
84 	if (!ops)
85 		return -ENOMEM;
86 
87 	for (i = 0; i < ARRAY_SIZE(nf_nat_ipv6_ops); i++) {
88 		ops[i].priv = table;
89 		ret = nf_nat_ipv6_register_fn(net, &ops[i]);
90 		if (ret) {
91 			while (i)
92 				nf_nat_ipv6_unregister_fn(net, &ops[--i]);
93 
94 			kfree(ops);
95 			return ret;
96 		}
97 	}
98 
99 	xt_nat_net->nf_nat_ops = ops;
100 	return 0;
101 }
102 
103 static void ip6t_nat_unregister_lookups(struct net *net)
104 {
105 	struct ip6table_nat_pernet *xt_nat_net = net_generic(net, ip6table_nat_net_id);
106 	struct nf_hook_ops *ops = xt_nat_net->nf_nat_ops;
107 	int i;
108 
109 	if (!ops)
110 		return;
111 
112 	for (i = 0; i < ARRAY_SIZE(nf_nat_ipv6_ops); i++)
113 		nf_nat_ipv6_unregister_fn(net, &ops[i]);
114 
115 	kfree(ops);
116 }
117 
118 static int __net_init ip6table_nat_table_init(struct net *net)
119 {
120 	struct ip6t_replace *repl;
121 	int ret;
122 
123 	repl = ip6t_alloc_initial_table(&nf_nat_ipv6_table);
124 	if (repl == NULL)
125 		return -ENOMEM;
126 	ret = ip6t_register_table(net, &nf_nat_ipv6_table, repl,
127 				  NULL);
128 	if (ret < 0) {
129 		kfree(repl);
130 		return ret;
131 	}
132 
133 	ret = ip6t_nat_register_lookups(net);
134 	if (ret < 0)
135 		ip6t_unregister_table_exit(net, "nat");
136 
137 	kfree(repl);
138 	return ret;
139 }
140 
141 static void __net_exit ip6table_nat_net_pre_exit(struct net *net)
142 {
143 	ip6t_nat_unregister_lookups(net);
144 }
145 
146 static void __net_exit ip6table_nat_net_exit(struct net *net)
147 {
148 	ip6t_unregister_table_exit(net, "nat");
149 }
150 
151 static struct pernet_operations ip6table_nat_net_ops = {
152 	.pre_exit = ip6table_nat_net_pre_exit,
153 	.exit	= ip6table_nat_net_exit,
154 	.id	= &ip6table_nat_net_id,
155 	.size	= sizeof(struct ip6table_nat_pernet),
156 };
157 
158 static int __init ip6table_nat_init(void)
159 {
160 	int ret = register_pernet_subsys(&ip6table_nat_net_ops);
161 
162 	if (ret)
163 		return ret;
164 
165 	ret = ip6table_nat_table_init(&init_net);
166 	if (ret)
167 		unregister_pernet_subsys(&ip6table_nat_net_ops);
168 	return ret;
169 }
170 
171 static void __exit ip6table_nat_exit(void)
172 {
173 	unregister_pernet_subsys(&ip6table_nat_net_ops);
174 }
175 
176 module_init(ip6table_nat_init);
177 module_exit(ip6table_nat_exit);
178 
179 MODULE_LICENSE("GPL");
180