net/ipv6/netfilter/nf_nat_masquerade_ipv6.c

   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
  24 unsigned int
  25 nf_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(nf_ct_net(ct), 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 }
  51 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6);
  52
  53 static 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
  64 static 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
  77 static struct notifier_block masq_dev_notifier = {
  78         .notifier_call  = masq_device_event,
  79 };
  80
  81 static 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
  91 static struct notifier_block masq_inet_notifier = {
  92         .notifier_call  = masq_inet_event,
  93 };
  94
  95 static atomic_t masquerade_notifier_refcount = ATOMIC_INIT(0);
  96
  97 void 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 }
 106 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_register_notifier);
 107
 108 void 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 }
 117 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_unregister_notifier);
 118
 119 MODULE_LICENSE("GPL");
 120 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");