1/* Masquerade.  Simple mapping which alters range to a local IP address
2   (depending on route). */
3
4/* (C) 1999-2001 Paul `Rusty' Russell
5 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12#include <linux/types.h>
13#include <linux/inetdevice.h>
14#include <linux/ip.h>
15#include <linux/timer.h>
16#include <linux/module.h>
17#include <linux/netfilter.h>
18#include <net/protocol.h>
19#include <net/ip.h>
20#include <net/checksum.h>
21#include <net/route.h>
22#include <linux/netfilter_ipv4.h>
23#include <linux/netfilter/x_tables.h>
24#include <net/netfilter/nf_nat.h>
25#include <net/netfilter/ipv4/nf_nat_masquerade.h>
26
27MODULE_LICENSE("GPL");
28MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
29MODULE_DESCRIPTION("Xtables: automatic-address SNAT");
30
31/* FIXME: Multiple targets. --RR */
32static int masquerade_tg_check(const struct xt_tgchk_param *par)
33{
34	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
35
36	if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
37		pr_debug("bad MAP_IPS.\n");
38		return -EINVAL;
39	}
40	if (mr->rangesize != 1) {
41		pr_debug("bad rangesize %u\n", mr->rangesize);
42		return -EINVAL;
43	}
44	return 0;
45}
46
47static unsigned int
48masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
49{
50	struct nf_nat_range range;
51	const struct nf_nat_ipv4_multi_range_compat *mr;
52
53	mr = par->targinfo;
54	range.flags = mr->range[0].flags;
55	range.min_proto = mr->range[0].min;
56	range.max_proto = mr->range[0].max;
57
58	return nf_nat_masquerade_ipv4(skb, par->hooknum, &range, par->out);
59}
60
61static struct xt_target masquerade_tg_reg __read_mostly = {
62	.name		= "MASQUERADE",
63	.family		= NFPROTO_IPV4,
64	.target		= masquerade_tg,
65	.targetsize	= sizeof(struct nf_nat_ipv4_multi_range_compat),
66	.table		= "nat",
67	.hooks		= 1 << NF_INET_POST_ROUTING,
68	.checkentry	= masquerade_tg_check,
69	.me		= THIS_MODULE,
70};
71
72static int __init masquerade_tg_init(void)
73{
74	int ret;
75
76	ret = xt_register_target(&masquerade_tg_reg);
77
78	if (ret == 0)
79		nf_nat_masquerade_ipv4_register_notifier();
80
81	return ret;
82}
83
84static void __exit masquerade_tg_exit(void)
85{
86	xt_unregister_target(&masquerade_tg_reg);
87	nf_nat_masquerade_ipv4_unregister_notifier();
88}
89
90module_init(masquerade_tg_init);
91module_exit(masquerade_tg_exit);
92