1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
4 * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
5 */
6
7#include <linux/ip.h>
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/netdevice.h>
11#include <linux/ipv6.h>
12#include <linux/netfilter.h>
13#include <linux/netfilter_ipv4.h>
14#include <linux/netfilter_ipv6.h>
15#include <linux/netfilter/x_tables.h>
16#include <net/netfilter/nf_nat.h>
17
18static unsigned int
19netmap_tg6(struct sk_buff *skb, const struct xt_action_param *par)
20{
21	const struct nf_nat_range2 *range = par->targinfo;
22	struct nf_nat_range2 newrange;
23	struct nf_conn *ct;
24	enum ip_conntrack_info ctinfo;
25	union nf_inet_addr new_addr, netmask;
26	unsigned int i;
27
28	ct = nf_ct_get(skb, &ctinfo);
29	for (i = 0; i < ARRAY_SIZE(range->min_addr.ip6); i++)
30		netmask.ip6[i] = ~(range->min_addr.ip6[i] ^
31				   range->max_addr.ip6[i]);
32
33	if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
34	    xt_hooknum(par) == NF_INET_LOCAL_OUT)
35		new_addr.in6 = ipv6_hdr(skb)->daddr;
36	else
37		new_addr.in6 = ipv6_hdr(skb)->saddr;
38
39	for (i = 0; i < ARRAY_SIZE(new_addr.ip6); i++) {
40		new_addr.ip6[i] &= ~netmask.ip6[i];
41		new_addr.ip6[i] |= range->min_addr.ip6[i] &
42				   netmask.ip6[i];
43	}
44
45	newrange.flags	= range->flags | NF_NAT_RANGE_MAP_IPS;
46	newrange.min_addr	= new_addr;
47	newrange.max_addr	= new_addr;
48	newrange.min_proto	= range->min_proto;
49	newrange.max_proto	= range->max_proto;
50
51	return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
52}
53
54static int netmap_tg6_checkentry(const struct xt_tgchk_param *par)
55{
56	const struct nf_nat_range2 *range = par->targinfo;
57
58	if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
59		return -EINVAL;
60	return nf_ct_netns_get(par->net, par->family);
61}
62
63static void netmap_tg_destroy(const struct xt_tgdtor_param *par)
64{
65	nf_ct_netns_put(par->net, par->family);
66}
67
68static unsigned int
69netmap_tg4(struct sk_buff *skb, const struct xt_action_param *par)
70{
71	struct nf_conn *ct;
72	enum ip_conntrack_info ctinfo;
73	__be32 new_ip, netmask;
74	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
75	struct nf_nat_range2 newrange;
76
77	WARN_ON(xt_hooknum(par) != NF_INET_PRE_ROUTING &&
78		xt_hooknum(par) != NF_INET_POST_ROUTING &&
79		xt_hooknum(par) != NF_INET_LOCAL_OUT &&
80		xt_hooknum(par) != NF_INET_LOCAL_IN);
81	ct = nf_ct_get(skb, &ctinfo);
82
83	netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
84
85	if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
86	    xt_hooknum(par) == NF_INET_LOCAL_OUT)
87		new_ip = ip_hdr(skb)->daddr & ~netmask;
88	else
89		new_ip = ip_hdr(skb)->saddr & ~netmask;
90	new_ip |= mr->range[0].min_ip & netmask;
91
92	memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
93	memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
94	newrange.flags	     = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
95	newrange.min_addr.ip = new_ip;
96	newrange.max_addr.ip = new_ip;
97	newrange.min_proto   = mr->range[0].min;
98	newrange.max_proto   = mr->range[0].max;
99
100	/* Hand modified range to generic setup. */
101	return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
102}
103
104static int netmap_tg4_check(const struct xt_tgchk_param *par)
105{
106	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
107
108	if (!(mr->range[0].flags & NF_NAT_RANGE_MAP_IPS)) {
109		pr_debug("bad MAP_IPS.\n");
110		return -EINVAL;
111	}
112	if (mr->rangesize != 1) {
113		pr_debug("bad rangesize %u.\n", mr->rangesize);
114		return -EINVAL;
115	}
116	return nf_ct_netns_get(par->net, par->family);
117}
118
119static struct xt_target netmap_tg_reg[] __read_mostly = {
120	{
121		.name       = "NETMAP",
122		.family     = NFPROTO_IPV6,
123		.revision   = 0,
124		.target     = netmap_tg6,
125		.targetsize = sizeof(struct nf_nat_range),
126		.table      = "nat",
127		.hooks      = (1 << NF_INET_PRE_ROUTING) |
128		              (1 << NF_INET_POST_ROUTING) |
129		              (1 << NF_INET_LOCAL_OUT) |
130		              (1 << NF_INET_LOCAL_IN),
131		.checkentry = netmap_tg6_checkentry,
132		.destroy    = netmap_tg_destroy,
133		.me         = THIS_MODULE,
134	},
135	{
136		.name       = "NETMAP",
137		.family     = NFPROTO_IPV4,
138		.revision   = 0,
139		.target     = netmap_tg4,
140		.targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
141		.table      = "nat",
142		.hooks      = (1 << NF_INET_PRE_ROUTING) |
143		              (1 << NF_INET_POST_ROUTING) |
144		              (1 << NF_INET_LOCAL_OUT) |
145		              (1 << NF_INET_LOCAL_IN),
146		.checkentry = netmap_tg4_check,
147		.destroy    = netmap_tg_destroy,
148		.me         = THIS_MODULE,
149	},
150};
151
152static int __init netmap_tg_init(void)
153{
154	return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
155}
156
157static void netmap_tg_exit(void)
158{
159	xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
160}
161
162module_init(netmap_tg_init);
163module_exit(netmap_tg_exit);
164
165MODULE_LICENSE("GPL");
166MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
167MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
168MODULE_ALIAS("ip6t_NETMAP");
169MODULE_ALIAS("ipt_NETMAP");
170