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
28static unsigned int
29redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par)
30{
31 return nf_nat_redirect_ipv6(skb, range: par->targinfo, hooknum: xt_hooknum(par));
32}
33
34static 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(net: par->net, nfproto: par->family);
42}
43
44static void redirect_tg_destroy(const struct xt_tgdtor_param *par)
45{
46 nf_ct_netns_put(net: par->net, nfproto: par->family);
47}
48
49static 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(net: par->net, nfproto: par->family);
62}
63
64static unsigned int
65redirect_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: &range, hooknum: xt_hooknum(par));
75}
76
77static 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
106static int __init redirect_tg_init(void)
107{
108 return xt_register_targets(target: redirect_tg_reg,
109 ARRAY_SIZE(redirect_tg_reg));
110}
111
112static void __exit redirect_tg_exit(void)
113{
114 xt_unregister_targets(target: redirect_tg_reg, ARRAY_SIZE(redirect_tg_reg));
115}
116
117module_init(redirect_tg_init);
118module_exit(redirect_tg_exit);
119
120MODULE_LICENSE("GPL");
121MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
122MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
123MODULE_ALIAS("ip6t_REDIRECT");
124MODULE_ALIAS("ipt_REDIRECT");
125

source code of linux/net/netfilter/xt_REDIRECT.c