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/netdevice.h>
16 #include <linux/netfilter.h>
17 #include <linux/types.h>
18 #include <linux/netfilter_ipv4.h>
19 #include <linux/netfilter_ipv6.h>
20 #include <linux/netfilter/x_tables.h>
21 #include <net/addrconf.h>
22 #include <net/checksum.h>
23 #include <net/protocol.h>
24 #include <net/netfilter/nf_nat.h>
25 #include <net/netfilter/nf_nat_redirect.h>
26
27 unsigned int
nf_nat_redirect_ipv4(struct sk_buff * skb,const struct nf_nat_ipv4_multi_range_compat * mr,unsigned int hooknum)28 nf_nat_redirect_ipv4(struct sk_buff *skb,
29 const struct nf_nat_ipv4_multi_range_compat *mr,
30 unsigned int hooknum)
31 {
32 struct nf_conn *ct;
33 enum ip_conntrack_info ctinfo;
34 __be32 newdst;
35 struct nf_nat_range2 newrange;
36
37 WARN_ON(hooknum != NF_INET_PRE_ROUTING &&
38 hooknum != NF_INET_LOCAL_OUT);
39
40 ct = nf_ct_get(skb, &ctinfo);
41 WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)));
42
43 /* Local packets: make them go to loopback */
44 if (hooknum == NF_INET_LOCAL_OUT) {
45 newdst = htonl(0x7F000001);
46 } else {
47 const struct in_device *indev;
48
49 newdst = 0;
50
51 indev = __in_dev_get_rcu(skb->dev);
52 if (indev) {
53 const struct in_ifaddr *ifa;
54
55 ifa = rcu_dereference(indev->ifa_list);
56 if (ifa)
57 newdst = ifa->ifa_local;
58 }
59
60 if (!newdst)
61 return NF_DROP;
62 }
63
64 /* Transfer from original range. */
65 memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
66 memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
67 newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
68 newrange.min_addr.ip = newdst;
69 newrange.max_addr.ip = newdst;
70 newrange.min_proto = mr->range[0].min;
71 newrange.max_proto = mr->range[0].max;
72
73 /* Hand modified range to generic setup. */
74 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
75 }
76 EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv4);
77
78 static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
79
80 unsigned int
nf_nat_redirect_ipv6(struct sk_buff * skb,const struct nf_nat_range2 * range,unsigned int hooknum)81 nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range,
82 unsigned int hooknum)
83 {
84 struct nf_nat_range2 newrange;
85 struct in6_addr newdst;
86 enum ip_conntrack_info ctinfo;
87 struct nf_conn *ct;
88
89 ct = nf_ct_get(skb, &ctinfo);
90 if (hooknum == NF_INET_LOCAL_OUT) {
91 newdst = loopback_addr;
92 } else {
93 struct inet6_dev *idev;
94 struct inet6_ifaddr *ifa;
95 bool addr = false;
96
97 idev = __in6_dev_get(skb->dev);
98 if (idev != NULL) {
99 read_lock_bh(&idev->lock);
100 list_for_each_entry(ifa, &idev->addr_list, if_list) {
101 newdst = ifa->addr;
102 addr = true;
103 break;
104 }
105 read_unlock_bh(&idev->lock);
106 }
107
108 if (!addr)
109 return NF_DROP;
110 }
111
112 newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
113 newrange.min_addr.in6 = newdst;
114 newrange.max_addr.in6 = newdst;
115 newrange.min_proto = range->min_proto;
116 newrange.max_proto = range->max_proto;
117
118 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
119 }
120 EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv6);
121