1// SPDX-License-Identifier: GPL-2.0-only
2/* (C) 1999-2001 Paul `Rusty' Russell
3 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
4 * (C) 2011 Patrick McHardy <kaber@trash.net>
5 */
6
7#include <linux/module.h>
8#include <linux/netfilter.h>
9#include <linux/netfilter_ipv4.h>
10#include <linux/netfilter_ipv4/ip_tables.h>
11#include <linux/ip.h>
12#include <net/ip.h>
13
14#include <net/netfilter/nf_nat.h>
15
16struct iptable_nat_pernet {
17	struct nf_hook_ops *nf_nat_ops;
18};
19
20static unsigned int iptable_nat_net_id __read_mostly;
21
22static const struct xt_table nf_nat_ipv4_table = {
23	.name		= "nat",
24	.valid_hooks	= (1 << NF_INET_PRE_ROUTING) |
25			  (1 << NF_INET_POST_ROUTING) |
26			  (1 << NF_INET_LOCAL_OUT) |
27			  (1 << NF_INET_LOCAL_IN),
28	.me		= THIS_MODULE,
29	.af		= NFPROTO_IPV4,
30};
31
32static const struct nf_hook_ops nf_nat_ipv4_ops[] = {
33	{
34		.hook		= ipt_do_table,
35		.pf		= NFPROTO_IPV4,
36		.hooknum	= NF_INET_PRE_ROUTING,
37		.priority	= NF_IP_PRI_NAT_DST,
38	},
39	{
40		.hook		= ipt_do_table,
41		.pf		= NFPROTO_IPV4,
42		.hooknum	= NF_INET_POST_ROUTING,
43		.priority	= NF_IP_PRI_NAT_SRC,
44	},
45	{
46		.hook		= ipt_do_table,
47		.pf		= NFPROTO_IPV4,
48		.hooknum	= NF_INET_LOCAL_OUT,
49		.priority	= NF_IP_PRI_NAT_DST,
50	},
51	{
52		.hook		= ipt_do_table,
53		.pf		= NFPROTO_IPV4,
54		.hooknum	= NF_INET_LOCAL_IN,
55		.priority	= NF_IP_PRI_NAT_SRC,
56	},
57};
58
59static int ipt_nat_register_lookups(struct net *net)
60{
61	struct iptable_nat_pernet *xt_nat_net;
62	struct nf_hook_ops *ops;
63	struct xt_table *table;
64	int i, ret;
65
66	xt_nat_net = net_generic(net, iptable_nat_net_id);
67	table = xt_find_table(net, NFPROTO_IPV4, "nat");
68	if (WARN_ON_ONCE(!table))
69		return -ENOENT;
70
71	ops = kmemdup(nf_nat_ipv4_ops, sizeof(nf_nat_ipv4_ops), GFP_KERNEL);
72	if (!ops)
73		return -ENOMEM;
74
75	for (i = 0; i < ARRAY_SIZE(nf_nat_ipv4_ops); i++) {
76		ops[i].priv = table;
77		ret = nf_nat_ipv4_register_fn(net, &ops[i]);
78		if (ret) {
79			while (i)
80				nf_nat_ipv4_unregister_fn(net, &ops[--i]);
81
82			kfree(ops);
83			return ret;
84		}
85	}
86
87	xt_nat_net->nf_nat_ops = ops;
88	return 0;
89}
90
91static void ipt_nat_unregister_lookups(struct net *net)
92{
93	struct iptable_nat_pernet *xt_nat_net = net_generic(net, iptable_nat_net_id);
94	struct nf_hook_ops *ops = xt_nat_net->nf_nat_ops;
95	int i;
96
97	if (!ops)
98		return;
99
100	for (i = 0; i < ARRAY_SIZE(nf_nat_ipv4_ops); i++)
101		nf_nat_ipv4_unregister_fn(net, &ops[i]);
102
103	kfree(ops);
104}
105
106static int iptable_nat_table_init(struct net *net)
107{
108	struct ipt_replace *repl;
109	int ret;
110
111	repl = ipt_alloc_initial_table(&nf_nat_ipv4_table);
112	if (repl == NULL)
113		return -ENOMEM;
114
115	ret = ipt_register_table(net, &nf_nat_ipv4_table, repl, NULL);
116	if (ret < 0) {
117		kfree(repl);
118		return ret;
119	}
120
121	ret = ipt_nat_register_lookups(net);
122	if (ret < 0)
123		ipt_unregister_table_exit(net, "nat");
124
125	kfree(repl);
126	return ret;
127}
128
129static void __net_exit iptable_nat_net_pre_exit(struct net *net)
130{
131	ipt_nat_unregister_lookups(net);
132}
133
134static void __net_exit iptable_nat_net_exit(struct net *net)
135{
136	ipt_unregister_table_exit(net, "nat");
137}
138
139static struct pernet_operations iptable_nat_net_ops = {
140	.pre_exit = iptable_nat_net_pre_exit,
141	.exit	= iptable_nat_net_exit,
142	.id	= &iptable_nat_net_id,
143	.size	= sizeof(struct iptable_nat_pernet),
144};
145
146static int __init iptable_nat_init(void)
147{
148	int ret = xt_register_template(&nf_nat_ipv4_table,
149				       iptable_nat_table_init);
150
151	if (ret < 0)
152		return ret;
153
154	ret = register_pernet_subsys(&iptable_nat_net_ops);
155	if (ret < 0) {
156		xt_unregister_template(&nf_nat_ipv4_table);
157		return ret;
158	}
159
160	return ret;
161}
162
163static void __exit iptable_nat_exit(void)
164{
165	unregister_pernet_subsys(&iptable_nat_net_ops);
166	xt_unregister_template(&nf_nat_ipv4_table);
167}
168
169module_init(iptable_nat_init);
170module_exit(iptable_nat_exit);
171
172MODULE_LICENSE("GPL");
173MODULE_DESCRIPTION("iptables legacy nat table");
174