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;
35 struct nf_nat_range newrange;
37 ct = nf_ct_get(skb, &ctinfo);
38 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
39 ctinfo == IP_CT_RELATED_REPLY));
41 if (ipv6_dev_get_saddr(nf_ct_net(ct), out,
42 &ipv6_hdr(skb)->daddr, 0, &src) < 0)
45 nfct_nat(ct)->masq_index = out->ifindex;
47 newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
48 newrange.min_addr.in6 = src;
49 newrange.max_addr.in6 = src;
50 newrange.min_proto = range->min_proto;
51 newrange.max_proto = range->max_proto;
53 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
55 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6);
57 static int device_cmp(struct nf_conn *ct, void *ifindex)
59 const struct nf_conn_nat *nat = nfct_nat(ct);
63 if (nf_ct_l3num(ct) != NFPROTO_IPV6)
65 return nat->masq_index == (int)(long)ifindex;
68 static int masq_device_event(struct notifier_block *this,
69 unsigned long event, void *ptr)
71 const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
72 struct net *net = dev_net(dev);
74 if (event == NETDEV_DOWN)
75 nf_ct_iterate_cleanup(net, device_cmp,
76 (void *)(long)dev->ifindex, 0, 0);
81 static struct notifier_block masq_dev_notifier = {
82 .notifier_call = masq_device_event,
85 struct masq_dev_work {
86 struct work_struct work;
91 static void iterate_cleanup_work(struct work_struct *work)
93 struct masq_dev_work *w;
96 w = container_of(work, struct masq_dev_work, work);
99 nf_ct_iterate_cleanup(w->net, device_cmp, (void *)index, 0, 0);
103 atomic_dec(&v6_worker_count);
104 module_put(THIS_MODULE);
107 /* ipv6 inet notifier is an atomic notifier, i.e. we cannot
110 * Unfortunately, nf_ct_iterate_cleanup can run for a long
111 * time if there are lots of conntracks and the system
112 * handles high softirq load, so it frequently calls cond_resched
113 * while iterating the conntrack table.
115 * So we defer nf_ct_iterate_cleanup walk to the system workqueue.
117 * As we can have 'a lot' of inet_events (depending on amount
118 * of ipv6 addresses being deleted), we also need to add an upper
119 * limit to the number of queued work items.
121 static int masq_inet_event(struct notifier_block *this,
122 unsigned long event, void *ptr)
124 struct inet6_ifaddr *ifa = ptr;
125 const struct net_device *dev;
126 struct masq_dev_work *w;
129 if (event != NETDEV_DOWN ||
130 atomic_read(&v6_worker_count) >= MAX_WORK_COUNT)
133 dev = ifa->idev->dev;
134 net = maybe_get_net(dev_net(dev));
138 if (!try_module_get(THIS_MODULE))
141 w = kmalloc(sizeof(*w), GFP_ATOMIC);
143 atomic_inc(&v6_worker_count);
145 INIT_WORK(&w->work, iterate_cleanup_work);
146 w->ifindex = dev->ifindex;
148 schedule_work(&w->work);
153 module_put(THIS_MODULE);
159 static struct notifier_block masq_inet_notifier = {
160 .notifier_call = masq_inet_event,
163 static atomic_t masquerade_notifier_refcount = ATOMIC_INIT(0);
165 void nf_nat_masquerade_ipv6_register_notifier(void)
167 /* check if the notifier is already set */
168 if (atomic_inc_return(&masquerade_notifier_refcount) > 1)
171 register_netdevice_notifier(&masq_dev_notifier);
172 register_inet6addr_notifier(&masq_inet_notifier);
174 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_register_notifier);
176 void nf_nat_masquerade_ipv6_unregister_notifier(void)
178 /* check if the notifier still has clients */
179 if (atomic_dec_return(&masquerade_notifier_refcount) > 0)
182 unregister_inet6addr_notifier(&masq_inet_notifier);
183 unregister_netdevice_notifier(&masq_dev_notifier);
185 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_unregister_notifier);
187 MODULE_LICENSE("GPL");
188 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");