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
18 static unsigned int
netmap_tg6(struct sk_buff * skb,const struct xt_action_param * par)19 netmap_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
netmap_tg6_checkentry(const struct xt_tgchk_param * par)54 static 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
netmap_tg_destroy(const struct xt_tgdtor_param * par)63 static void netmap_tg_destroy(const struct xt_tgdtor_param *par)
64 {
65 nf_ct_netns_put(par->net, par->family);
66 }
67
68 static unsigned int
netmap_tg4(struct sk_buff * skb,const struct xt_action_param * par)69 netmap_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
netmap_tg4_check(const struct xt_tgchk_param * par)104 static 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
119 static 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
netmap_tg_init(void)152 static int __init netmap_tg_init(void)
153 {
154 return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
155 }
156
netmap_tg_exit(void)157 static void netmap_tg_exit(void)
158 {
159 xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
160 }
161
162 module_init(netmap_tg_init);
163 module_exit(netmap_tg_exit);
164
165 MODULE_LICENSE("GPL");
166 MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
167 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
168 MODULE_ALIAS("ip6t_NETMAP");
169 MODULE_ALIAS("ipt_NETMAP");
170