1/*
2 * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * Based on Rusty Russell's IPv6 MASQUERADE target. Development of IPv6
9 * NAT funded by Astaro.
10 */
11
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/atomic.h>
15#include <linux/netdevice.h>
16#include <linux/ipv6.h>
17#include <linux/netfilter.h>
18#include <linux/netfilter_ipv6.h>
19#include <net/netfilter/nf_nat.h>
20#include <net/addrconf.h>
21#include <net/ipv6.h>
22#include <net/netfilter/ipv6/nf_nat_masquerade.h>
23
24unsigned int
25nf_nat_masquerade_ipv6(struct sk_buff *skb, const struct nf_nat_range *range,
26		       const struct net_device *out)
27{
28	enum ip_conntrack_info ctinfo;
29	struct in6_addr src;
30	struct nf_conn *ct;
31	struct nf_nat_range newrange;
32
33	ct = nf_ct_get(skb, &ctinfo);
34	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
35			    ctinfo == IP_CT_RELATED_REPLY));
36
37	if (ipv6_dev_get_saddr(dev_net(out), out,
38			       &ipv6_hdr(skb)->daddr, 0, &src) < 0)
39		return NF_DROP;
40
41	nfct_nat(ct)->masq_index = out->ifindex;
42
43	newrange.flags		= range->flags | NF_NAT_RANGE_MAP_IPS;
44	newrange.min_addr.in6	= src;
45	newrange.max_addr.in6	= src;
46	newrange.min_proto	= range->min_proto;
47	newrange.max_proto	= range->max_proto;
48
49	return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
50}
51EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6);
52
53static int device_cmp(struct nf_conn *ct, void *ifindex)
54{
55	const struct nf_conn_nat *nat = nfct_nat(ct);
56
57	if (!nat)
58		return 0;
59	if (nf_ct_l3num(ct) != NFPROTO_IPV6)
60		return 0;
61	return nat->masq_index == (int)(long)ifindex;
62}
63
64static int masq_device_event(struct notifier_block *this,
65			     unsigned long event, void *ptr)
66{
67	const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
68	struct net *net = dev_net(dev);
69
70	if (event == NETDEV_DOWN)
71		nf_ct_iterate_cleanup(net, device_cmp,
72				      (void *)(long)dev->ifindex, 0, 0);
73
74	return NOTIFY_DONE;
75}
76
77static struct notifier_block masq_dev_notifier = {
78	.notifier_call	= masq_device_event,
79};
80
81static int masq_inet_event(struct notifier_block *this,
82			   unsigned long event, void *ptr)
83{
84	struct inet6_ifaddr *ifa = ptr;
85	struct netdev_notifier_info info;
86
87	netdev_notifier_info_init(&info, ifa->idev->dev);
88	return masq_device_event(this, event, &info);
89}
90
91static struct notifier_block masq_inet_notifier = {
92	.notifier_call	= masq_inet_event,
93};
94
95static atomic_t masquerade_notifier_refcount = ATOMIC_INIT(0);
96
97void nf_nat_masquerade_ipv6_register_notifier(void)
98{
99	/* check if the notifier is already set */
100	if (atomic_inc_return(&masquerade_notifier_refcount) > 1)
101		return;
102
103	register_netdevice_notifier(&masq_dev_notifier);
104	register_inet6addr_notifier(&masq_inet_notifier);
105}
106EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_register_notifier);
107
108void nf_nat_masquerade_ipv6_unregister_notifier(void)
109{
110	/* check if the notifier still has clients */
111	if (atomic_dec_return(&masquerade_notifier_refcount) > 0)
112		return;
113
114	unregister_inet6addr_notifier(&masq_inet_notifier);
115	unregister_netdevice_notifier(&masq_dev_notifier);
116}
117EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_unregister_notifier);
118
119MODULE_LICENSE("GPL");
120MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
121