2 * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
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.
8 * Based on Rusty Russell's IPv6 MASQUERADE target. Development of IPv6
9 * NAT funded by Astaro.
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>
22 #include <net/netfilter/ipv6/nf_nat_masquerade.h>
24 #define MAX_WORK_COUNT 16
26 static atomic_t v6_worker_count;
29 nf_nat_masquerade_ipv6(struct sk_buff *skb, const struct nf_nat_range *range,
30 const struct net_device *out)
32 enum ip_conntrack_info ctinfo;
33 struct nf_conn_nat *nat;
36 struct nf_nat_range newrange;
38 ct = nf_ct_get(skb, &ctinfo);
39 WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
40 ctinfo == IP_CT_RELATED_REPLY)));
42 if (ipv6_dev_get_saddr(nf_ct_net(ct), out,
43 &ipv6_hdr(skb)->daddr, 0, &src) < 0)
46 nat = nf_ct_nat_ext_add(ct);
48 nat->masq_index = out->ifindex;
50 newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
51 newrange.min_addr.in6 = src;
52 newrange.max_addr.in6 = src;
53 newrange.min_proto = range->min_proto;
54 newrange.max_proto = range->max_proto;
56 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
58 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6);
60 static int device_cmp(struct nf_conn *ct, void *ifindex)
62 const struct nf_conn_nat *nat = nfct_nat(ct);
66 if (nf_ct_l3num(ct) != NFPROTO_IPV6)
68 return nat->masq_index == (int)(long)ifindex;
71 static int masq_device_event(struct notifier_block *this,
72 unsigned long event, void *ptr)
74 const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
75 struct net *net = dev_net(dev);
77 if (event == NETDEV_DOWN)
78 nf_ct_iterate_cleanup_net(net, device_cmp,
79 (void *)(long)dev->ifindex, 0, 0);
84 static struct notifier_block masq_dev_notifier = {
85 .notifier_call = masq_device_event,
88 struct masq_dev_work {
89 struct work_struct work;
95 static int inet_cmp(struct nf_conn *ct, void *work)
97 struct masq_dev_work *w = (struct masq_dev_work *)work;
98 struct nf_conntrack_tuple *tuple;
100 if (!device_cmp(ct, (void *)(long)w->ifindex))
103 tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
105 return ipv6_addr_equal(&w->addr, &tuple->dst.u3.in6);
108 static void iterate_cleanup_work(struct work_struct *work)
110 struct masq_dev_work *w;
112 w = container_of(work, struct masq_dev_work, work);
114 nf_ct_iterate_cleanup_net(w->net, inet_cmp, (void *)w, 0, 0);
118 atomic_dec(&v6_worker_count);
119 module_put(THIS_MODULE);
122 /* ipv6 inet notifier is an atomic notifier, i.e. we cannot
125 * Unfortunately, nf_ct_iterate_cleanup_net can run for a long
126 * time if there are lots of conntracks and the system
127 * handles high softirq load, so it frequently calls cond_resched
128 * while iterating the conntrack table.
130 * So we defer nf_ct_iterate_cleanup_net walk to the system workqueue.
132 * As we can have 'a lot' of inet_events (depending on amount
133 * of ipv6 addresses being deleted), we also need to add an upper
134 * limit to the number of queued work items.
136 static int masq_inet_event(struct notifier_block *this,
137 unsigned long event, void *ptr)
139 struct inet6_ifaddr *ifa = ptr;
140 const struct net_device *dev;
141 struct masq_dev_work *w;
144 if (event != NETDEV_DOWN ||
145 atomic_read(&v6_worker_count) >= MAX_WORK_COUNT)
148 dev = ifa->idev->dev;
149 net = maybe_get_net(dev_net(dev));
153 if (!try_module_get(THIS_MODULE))
156 w = kmalloc(sizeof(*w), GFP_ATOMIC);
158 atomic_inc(&v6_worker_count);
160 INIT_WORK(&w->work, iterate_cleanup_work);
161 w->ifindex = dev->ifindex;
164 schedule_work(&w->work);
169 module_put(THIS_MODULE);
175 static struct notifier_block masq_inet_notifier = {
176 .notifier_call = masq_inet_event,
179 static atomic_t masquerade_notifier_refcount = ATOMIC_INIT(0);
181 void nf_nat_masquerade_ipv6_register_notifier(void)
183 /* check if the notifier is already set */
184 if (atomic_inc_return(&masquerade_notifier_refcount) > 1)
187 register_netdevice_notifier(&masq_dev_notifier);
188 register_inet6addr_notifier(&masq_inet_notifier);
190 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_register_notifier);
192 void nf_nat_masquerade_ipv6_unregister_notifier(void)
194 /* check if the notifier still has clients */
195 if (atomic_dec_return(&masquerade_notifier_refcount) > 0)
198 unregister_inet6addr_notifier(&masq_inet_notifier);
199 unregister_netdevice_notifier(&masq_dev_notifier);
201 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_unregister_notifier);
203 MODULE_LICENSE("GPL");
204 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");