1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * (C) 1999-2001 Paul `Rusty' Russell
4 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
5 * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
6 *
7 * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
8 * NAT funded by Astaro.
9 */
10
11 #include <linux/if.h>
12 #include <linux/inetdevice.h>
13 #include <linux/ip.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/netdevice.h>
17 #include <linux/netfilter.h>
18 #include <linux/types.h>
19 #include <linux/netfilter_ipv4.h>
20 #include <linux/netfilter_ipv6.h>
21 #include <linux/netfilter/x_tables.h>
22 #include <net/addrconf.h>
23 #include <net/checksum.h>
24 #include <net/protocol.h>
25 #include <net/netfilter/nf_nat.h>
26 #include <net/netfilter/nf_nat_redirect.h>
27
28 static unsigned int
redirect_tg6(struct sk_buff * skb,const struct xt_action_param * par)29 redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par)
30 {
31 return nf_nat_redirect_ipv6(skb, par->targinfo, xt_hooknum(par));
32 }
33
redirect_tg6_checkentry(const struct xt_tgchk_param * par)34 static int redirect_tg6_checkentry(const struct xt_tgchk_param *par)
35 {
36 const struct nf_nat_range2 *range = par->targinfo;
37
38 if (range->flags & NF_NAT_RANGE_MAP_IPS)
39 return -EINVAL;
40
41 return nf_ct_netns_get(par->net, par->family);
42 }
43
redirect_tg_destroy(const struct xt_tgdtor_param * par)44 static void redirect_tg_destroy(const struct xt_tgdtor_param *par)
45 {
46 nf_ct_netns_put(par->net, par->family);
47 }
48
redirect_tg4_check(const struct xt_tgchk_param * par)49 static int redirect_tg4_check(const struct xt_tgchk_param *par)
50 {
51 const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
52
53 if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
54 pr_debug("bad MAP_IPS.\n");
55 return -EINVAL;
56 }
57 if (mr->rangesize != 1) {
58 pr_debug("bad rangesize %u.\n", mr->rangesize);
59 return -EINVAL;
60 }
61 return nf_ct_netns_get(par->net, par->family);
62 }
63
64 static unsigned int
redirect_tg4(struct sk_buff * skb,const struct xt_action_param * par)65 redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par)
66 {
67 const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
68 struct nf_nat_range2 range = {
69 .flags = mr->range[0].flags,
70 .min_proto = mr->range[0].min,
71 .max_proto = mr->range[0].max,
72 };
73
74 return nf_nat_redirect_ipv4(skb, &range, xt_hooknum(par));
75 }
76
77 static struct xt_target redirect_tg_reg[] __read_mostly = {
78 {
79 .name = "REDIRECT",
80 .family = NFPROTO_IPV6,
81 .revision = 0,
82 .table = "nat",
83 .checkentry = redirect_tg6_checkentry,
84 .destroy = redirect_tg_destroy,
85 .target = redirect_tg6,
86 .targetsize = sizeof(struct nf_nat_range),
87 .hooks = (1 << NF_INET_PRE_ROUTING) |
88 (1 << NF_INET_LOCAL_OUT),
89 .me = THIS_MODULE,
90 },
91 {
92 .name = "REDIRECT",
93 .family = NFPROTO_IPV4,
94 .revision = 0,
95 .table = "nat",
96 .target = redirect_tg4,
97 .checkentry = redirect_tg4_check,
98 .destroy = redirect_tg_destroy,
99 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
100 .hooks = (1 << NF_INET_PRE_ROUTING) |
101 (1 << NF_INET_LOCAL_OUT),
102 .me = THIS_MODULE,
103 },
104 };
105
redirect_tg_init(void)106 static int __init redirect_tg_init(void)
107 {
108 return xt_register_targets(redirect_tg_reg,
109 ARRAY_SIZE(redirect_tg_reg));
110 }
111
redirect_tg_exit(void)112 static void __exit redirect_tg_exit(void)
113 {
114 xt_unregister_targets(redirect_tg_reg, ARRAY_SIZE(redirect_tg_reg));
115 }
116
117 module_init(redirect_tg_init);
118 module_exit(redirect_tg_exit);
119
120 MODULE_LICENSE("GPL");
121 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
122 MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
123 MODULE_ALIAS("ip6t_REDIRECT");
124 MODULE_ALIAS("ipt_REDIRECT");
125