1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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.
9 #include <linux/types.h>
10 #include <linux/module.h>
11 #include <linux/atomic.h>
12 #include <linux/inetdevice.h>
14 #include <linux/timer.h>
15 #include <linux/netfilter.h>
16 #include <net/protocol.h>
18 #include <net/checksum.h>
19 #include <net/route.h>
20 #include <linux/netfilter_ipv4.h>
21 #include <linux/netfilter/x_tables.h>
22 #include <net/netfilter/nf_nat.h>
23 #include <net/netfilter/ipv4/nf_nat_masquerade.h>
26 nf_nat_masquerade_ipv4(struct sk_buff *skb, unsigned int hooknum,
27 const struct nf_nat_range *range,
28 const struct net_device *out)
31 struct nf_conn_nat *nat;
32 enum ip_conntrack_info ctinfo;
33 struct nf_nat_range newrange;
34 const struct rtable *rt;
37 NF_CT_ASSERT(hooknum == NF_INET_POST_ROUTING);
39 ct = nf_ct_get(skb, &ctinfo);
41 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
42 ctinfo == IP_CT_RELATED_REPLY));
44 /* Source address is 0.0.0.0 - locally generated packet that is
45 * probably not supposed to be masqueraded.
47 if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0)
51 nh = rt_nexthop(rt, ip_hdr(skb)->daddr);
52 newsrc = inet_select_addr(out, nh, RT_SCOPE_UNIVERSE);
54 pr_info("%s ate my IP address\n", out->name);
58 nat = nf_ct_nat_ext_add(ct);
60 nat->masq_index = out->ifindex;
62 /* Transfer from original range. */
63 memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
64 memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
65 newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
66 newrange.min_addr.ip = newsrc;
67 newrange.max_addr.ip = newsrc;
68 newrange.min_proto = range->min_proto;
69 newrange.max_proto = range->max_proto;
71 /* Hand modified range to generic setup. */
72 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
74 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4);
76 static int device_cmp(struct nf_conn *i, void *ifindex)
78 const struct nf_conn_nat *nat = nfct_nat(i);
82 if (nf_ct_l3num(i) != NFPROTO_IPV4)
84 return nat->masq_index == (int)(long)ifindex;
87 static int masq_device_event(struct notifier_block *this,
91 const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
92 struct net *net = dev_net(dev);
94 if (event == NETDEV_DOWN) {
95 /* Device was downed. Search entire table for
96 * conntracks which were associated with that device,
99 NF_CT_ASSERT(dev->ifindex != 0);
101 nf_ct_iterate_cleanup_net(net, device_cmp,
102 (void *)(long)dev->ifindex, 0, 0);
108 static int masq_inet_event(struct notifier_block *this,
112 struct in_device *idev = ((struct in_ifaddr *)ptr)->ifa_dev;
113 struct netdev_notifier_info info;
115 /* The masq_dev_notifier will catch the case of the device going
116 * down. So if the inetdev is dead and being destroyed we have
117 * no work to do. Otherwise this is an individual address removal
118 * and we have to perform the flush.
123 netdev_notifier_info_init(&info, idev->dev);
124 return masq_device_event(this, event, &info);
127 static struct notifier_block masq_dev_notifier = {
128 .notifier_call = masq_device_event,
131 static struct notifier_block masq_inet_notifier = {
132 .notifier_call = masq_inet_event,
135 static atomic_t masquerade_notifier_refcount = ATOMIC_INIT(0);
137 void nf_nat_masquerade_ipv4_register_notifier(void)
139 /* check if the notifier was already set */
140 if (atomic_inc_return(&masquerade_notifier_refcount) > 1)
143 /* Register for device down reports */
144 register_netdevice_notifier(&masq_dev_notifier);
145 /* Register IP address change reports */
146 register_inetaddr_notifier(&masq_inet_notifier);
148 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_register_notifier);
150 void nf_nat_masquerade_ipv4_unregister_notifier(void)
152 /* check if the notifier still has clients */
153 if (atomic_dec_return(&masquerade_notifier_refcount) > 0)
156 unregister_netdevice_notifier(&masq_dev_notifier);
157 unregister_inetaddr_notifier(&masq_inet_notifier);
159 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_unregister_notifier);
161 MODULE_LICENSE("GPL");
162 MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");