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