1// SPDX-License-Identifier: GPL-2.0-only
2/* Masquerade. Simple mapping which alters range to a local IP address
3 (depending on route). */
4
5/* (C) 1999-2001 Paul `Rusty' Russell
6 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
7 */
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9#include <linux/module.h>
10#include <linux/netfilter/x_tables.h>
11#include <net/netfilter/nf_nat.h>
12#include <net/netfilter/nf_nat_masquerade.h>
13
14MODULE_LICENSE("GPL");
15MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
16MODULE_DESCRIPTION("Xtables: automatic-address SNAT");
17
18/* FIXME: Multiple targets. --RR */
19static int masquerade_tg_check(const struct xt_tgchk_param *par)
20{
21 const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
22
23 if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
24 pr_debug("bad MAP_IPS.\n");
25 return -EINVAL;
26 }
27 if (mr->rangesize != 1) {
28 pr_debug("bad rangesize %u\n", mr->rangesize);
29 return -EINVAL;
30 }
31 return nf_ct_netns_get(net: par->net, nfproto: par->family);
32}
33
34static unsigned int
35masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
36{
37 struct nf_nat_range2 range;
38 const struct nf_nat_ipv4_multi_range_compat *mr;
39
40 mr = par->targinfo;
41 range.flags = mr->range[0].flags;
42 range.min_proto = mr->range[0].min;
43 range.max_proto = mr->range[0].max;
44
45 return nf_nat_masquerade_ipv4(skb, hooknum: xt_hooknum(par), range: &range,
46 out: xt_out(par));
47}
48
49static void masquerade_tg_destroy(const struct xt_tgdtor_param *par)
50{
51 nf_ct_netns_put(net: par->net, nfproto: par->family);
52}
53
54#if IS_ENABLED(CONFIG_IPV6)
55static unsigned int
56masquerade_tg6(struct sk_buff *skb, const struct xt_action_param *par)
57{
58 return nf_nat_masquerade_ipv6(skb, range: par->targinfo, out: xt_out(par));
59}
60
61static int masquerade_tg6_checkentry(const struct xt_tgchk_param *par)
62{
63 const struct nf_nat_range2 *range = par->targinfo;
64
65 if (range->flags & NF_NAT_RANGE_MAP_IPS)
66 return -EINVAL;
67
68 return nf_ct_netns_get(net: par->net, nfproto: par->family);
69}
70#endif
71
72static struct xt_target masquerade_tg_reg[] __read_mostly = {
73 {
74#if IS_ENABLED(CONFIG_IPV6)
75 .name = "MASQUERADE",
76 .family = NFPROTO_IPV6,
77 .target = masquerade_tg6,
78 .targetsize = sizeof(struct nf_nat_range),
79 .table = "nat",
80 .hooks = 1 << NF_INET_POST_ROUTING,
81 .checkentry = masquerade_tg6_checkentry,
82 .destroy = masquerade_tg_destroy,
83 .me = THIS_MODULE,
84 }, {
85#endif
86 .name = "MASQUERADE",
87 .family = NFPROTO_IPV4,
88 .target = masquerade_tg,
89 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
90 .table = "nat",
91 .hooks = 1 << NF_INET_POST_ROUTING,
92 .checkentry = masquerade_tg_check,
93 .destroy = masquerade_tg_destroy,
94 .me = THIS_MODULE,
95 }
96};
97
98static int __init masquerade_tg_init(void)
99{
100 int ret;
101
102 ret = xt_register_targets(target: masquerade_tg_reg,
103 ARRAY_SIZE(masquerade_tg_reg));
104 if (ret)
105 return ret;
106
107 ret = nf_nat_masquerade_inet_register_notifiers();
108 if (ret) {
109 xt_unregister_targets(target: masquerade_tg_reg,
110 ARRAY_SIZE(masquerade_tg_reg));
111 return ret;
112 }
113
114 return ret;
115}
116
117static void __exit masquerade_tg_exit(void)
118{
119 xt_unregister_targets(target: masquerade_tg_reg, ARRAY_SIZE(masquerade_tg_reg));
120 nf_nat_masquerade_inet_unregister_notifiers();
121}
122
123module_init(masquerade_tg_init);
124module_exit(masquerade_tg_exit);
125#if IS_ENABLED(CONFIG_IPV6)
126MODULE_ALIAS("ip6t_MASQUERADE");
127#endif
128MODULE_ALIAS("ipt_MASQUERADE");
129