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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * (C) 2000-2001 Svenning Soerensen <[email protected]>
4 * Copyright (c) 2011 Patrick McHardy <[email protected]>
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/ip.h>
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/netdevice.h>
13#include <linux/ipv6.h>
14#include <linux/netfilter.h>
15#include <linux/netfilter_ipv4.h>
16#include <linux/netfilter_ipv6.h>
17#include <linux/netfilter/x_tables.h>
18#include <net/netfilter/nf_nat.h>
19
20static unsigned int
21netmap_tg6(struct sk_buff *skb, const struct xt_action_param *par)
22{
23 const struct nf_nat_range2 *range = par->targinfo;
24 struct nf_nat_range2 newrange;
25 struct nf_conn *ct;
26 enum ip_conntrack_info ctinfo;
27 union nf_inet_addr new_addr, netmask;
28 unsigned int i;
29
30 ct = nf_ct_get(skb, &ctinfo);
31 for (i = 0; i < ARRAY_SIZE(range->min_addr.ip6); i++)
32 netmask.ip6[i] = ~(range->min_addr.ip6[i] ^
33 range->max_addr.ip6[i]);
34
35 if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
36 xt_hooknum(par) == NF_INET_LOCAL_OUT)
37 new_addr.in6 = ipv6_hdr(skb)->daddr;
38 else
39 new_addr.in6 = ipv6_hdr(skb)->saddr;
40
41 for (i = 0; i < ARRAY_SIZE(new_addr.ip6); i++) {
42 new_addr.ip6[i] &= ~netmask.ip6[i];
43 new_addr.ip6[i] |= range->min_addr.ip6[i] &
44 netmask.ip6[i];
45 }
46
47 newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
48 newrange.min_addr = new_addr;
49 newrange.max_addr = new_addr;
50 newrange.min_proto = range->min_proto;
51 newrange.max_proto = range->max_proto;
52
53 return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
54}
55
56static int netmap_tg6_checkentry(const struct xt_tgchk_param *par)
57{
58 const struct nf_nat_range2 *range = par->targinfo;
59
60 if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
61 return -EINVAL;
62 return nf_ct_netns_get(par->net, par->family);
63}
64
65static void netmap_tg_destroy(const struct xt_tgdtor_param *par)
66{
67 nf_ct_netns_put(par->net, par->family);
68}
69
70static unsigned int
71netmap_tg4(struct sk_buff *skb, const struct xt_action_param *par)
72{
73 struct nf_conn *ct;
74 enum ip_conntrack_info ctinfo;
75 __be32 new_ip, netmask;
76 const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
77 struct nf_nat_range2 newrange;
78
79 WARN_ON(xt_hooknum(par) != NF_INET_PRE_ROUTING &&
80 xt_hooknum(par) != NF_INET_POST_ROUTING &&
81 xt_hooknum(par) != NF_INET_LOCAL_OUT &&
82 xt_hooknum(par) != NF_INET_LOCAL_IN);
83 ct = nf_ct_get(skb, &ctinfo);
84
85 netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
86
87 if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
88 xt_hooknum(par) == NF_INET_LOCAL_OUT)
89 new_ip = ip_hdr(skb)->daddr & ~netmask;
90 else
91 new_ip = ip_hdr(skb)->saddr & ~netmask;
92 new_ip |= mr->range[0].min_ip & netmask;
93
94 memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
95 memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
96 newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
97 newrange.min_addr.ip = new_ip;
98 newrange.max_addr.ip = new_ip;
99 newrange.min_proto = mr->range[0].min;
100 newrange.max_proto = mr->range[0].max;
101
102 /* Hand modified range to generic setup. */
103 return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
104}
105
106static int netmap_tg4_check(const struct xt_tgchk_param *par)
107{
108 const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
109
110 if (!(mr->range[0].flags & NF_NAT_RANGE_MAP_IPS)) {
111 pr_info_ratelimited("bad MAP_IPS.\n");
112 return -EINVAL;
113 }
114 if (mr->rangesize != 1) {
115 pr_info_ratelimited("bad rangesize %u.\n", mr->rangesize);
116 return -EINVAL;
117 }
118 return nf_ct_netns_get(par->net, par->family);
119}
120
121static struct xt_target netmap_tg_reg[] __read_mostly = {
122 {
123 .name = "NETMAP",
124 .family = NFPROTO_IPV6,
125 .revision = 0,
126 .target = netmap_tg6,
127 .targetsize = sizeof(struct nf_nat_range),
128 .table = "nat",
129 .hooks = (1 << NF_INET_PRE_ROUTING) |
130 (1 << NF_INET_POST_ROUTING) |
131 (1 << NF_INET_LOCAL_OUT) |
132 (1 << NF_INET_LOCAL_IN),
133 .checkentry = netmap_tg6_checkentry,
134 .destroy = netmap_tg_destroy,
135 .me = THIS_MODULE,
136 },
137 {
138 .name = "NETMAP",
139 .family = NFPROTO_IPV4,
140 .revision = 0,
141 .target = netmap_tg4,
142 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
143 .table = "nat",
144 .hooks = (1 << NF_INET_PRE_ROUTING) |
145 (1 << NF_INET_POST_ROUTING) |
146 (1 << NF_INET_LOCAL_OUT) |
147 (1 << NF_INET_LOCAL_IN),
148 .checkentry = netmap_tg4_check,
149 .destroy = netmap_tg_destroy,
150 .me = THIS_MODULE,
151 },
152};
153
154static int __init netmap_tg_init(void)
155{
156 return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
157}
158
159static void netmap_tg_exit(void)
160{
161 xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
162}
163
164module_init(netmap_tg_init);
165module_exit(netmap_tg_exit);
166
167MODULE_LICENSE("GPL");
168MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
169MODULE_AUTHOR("Patrick McHardy <[email protected]>");
170MODULE_ALIAS("ip6t_NETMAP");
171MODULE_ALIAS("ipt_NETMAP");