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/in.h> |
14 | #include <linux/ip.h> |
15 | #include <linux/kernel.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 |
29 | nf_nat_redirect(struct sk_buff *skb, const struct nf_nat_range2 *range, |
30 | const union nf_inet_addr *newdst) |
31 | { |
32 | struct nf_nat_range2 newrange; |
33 | enum ip_conntrack_info ctinfo; |
34 | struct nf_conn *ct; |
35 | |
36 | ct = nf_ct_get(skb, ctinfo: &ctinfo); |
37 | |
38 | memset(&newrange, 0, sizeof(newrange)); |
39 | |
40 | newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS; |
41 | newrange.min_addr = *newdst; |
42 | newrange.max_addr = *newdst; |
43 | newrange.min_proto = range->min_proto; |
44 | newrange.max_proto = range->max_proto; |
45 | |
46 | return nf_nat_setup_info(ct, range: &newrange, maniptype: NF_NAT_MANIP_DST); |
47 | } |
48 | |
49 | unsigned int |
50 | nf_nat_redirect_ipv4(struct sk_buff *skb, const struct nf_nat_range2 *range, |
51 | unsigned int hooknum) |
52 | { |
53 | union nf_inet_addr newdst = {}; |
54 | |
55 | WARN_ON(hooknum != NF_INET_PRE_ROUTING && |
56 | hooknum != NF_INET_LOCAL_OUT); |
57 | |
58 | /* Local packets: make them go to loopback */ |
59 | if (hooknum == NF_INET_LOCAL_OUT) { |
60 | newdst.ip = htonl(INADDR_LOOPBACK); |
61 | } else { |
62 | const struct in_device *indev; |
63 | |
64 | indev = __in_dev_get_rcu(dev: skb->dev); |
65 | if (indev) { |
66 | const struct in_ifaddr *ifa; |
67 | |
68 | ifa = rcu_dereference(indev->ifa_list); |
69 | if (ifa) |
70 | newdst.ip = ifa->ifa_local; |
71 | } |
72 | |
73 | if (!newdst.ip) |
74 | return NF_DROP; |
75 | } |
76 | |
77 | return nf_nat_redirect(skb, range, newdst: &newdst); |
78 | } |
79 | EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv4); |
80 | |
81 | static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT; |
82 | |
83 | unsigned int |
84 | nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range, |
85 | unsigned int hooknum) |
86 | { |
87 | union nf_inet_addr newdst = {}; |
88 | |
89 | if (hooknum == NF_INET_LOCAL_OUT) { |
90 | newdst.in6 = loopback_addr; |
91 | } else { |
92 | struct inet6_dev *idev; |
93 | struct inet6_ifaddr *ifa; |
94 | bool addr = false; |
95 | |
96 | idev = __in6_dev_get(dev: skb->dev); |
97 | if (idev != NULL) { |
98 | read_lock_bh(&idev->lock); |
99 | list_for_each_entry(ifa, &idev->addr_list, if_list) { |
100 | newdst.in6 = ifa->addr; |
101 | addr = true; |
102 | break; |
103 | } |
104 | read_unlock_bh(&idev->lock); |
105 | } |
106 | |
107 | if (!addr) |
108 | return NF_DROP; |
109 | } |
110 | |
111 | return nf_nat_redirect(skb, range, newdst: &newdst); |
112 | } |
113 | EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv6); |
114 | |