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