Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 | /* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/types.h>
#include <linux/module.h>
#include <linux/atomic.h>
#include <linux/inetdevice.h>
#include <linux/ip.h>
#include <linux/timer.h>
#include <linux/netfilter.h>
#include <net/protocol.h>
#include <net/ip.h>
#include <net/checksum.h>
#include <net/route.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter/x_tables.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/ipv4/nf_nat_masquerade.h>
unsigned int
nf_nat_masquerade_ipv4(struct sk_buff *skb, unsigned int hooknum,
const struct nf_nat_range *range,
const struct net_device *out)
{
struct nf_conn *ct;
struct nf_conn_nat *nat;
enum ip_conntrack_info ctinfo;
struct nf_nat_range newrange;
const struct rtable *rt;
__be32 newsrc, nh;
NF_CT_ASSERT(hooknum == NF_INET_POST_ROUTING);
ct = nf_ct_get(skb, &ctinfo);
nat = nfct_nat(ct);
NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
ctinfo == IP_CT_RELATED_REPLY));
/* Source address is 0.0.0.0 - locally generated packet that is
* probably not supposed to be masqueraded.
*/
if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0)
return NF_ACCEPT;
rt = skb_rtable(skb);
nh = rt_nexthop(rt, ip_hdr(skb)->daddr);
newsrc = inet_select_addr(out, nh, RT_SCOPE_UNIVERSE);
if (!newsrc) {
pr_info("%s ate my IP address\n", out->name);
return NF_DROP;
}
nat->masq_index = out->ifindex;
/* Transfer from original range. */
memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
newrange.min_addr.ip = newsrc;
newrange.max_addr.ip = newsrc;
newrange.min_proto = range->min_proto;
newrange.max_proto = range->max_proto;
/* Hand modified range to generic setup. */
return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
}
EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4);
static int device_cmp(struct nf_conn *i, void *ifindex)
{
const struct nf_conn_nat *nat = nfct_nat(i);
if (!nat)
return 0;
if (nf_ct_l3num(i) != NFPROTO_IPV4)
return 0;
return nat->masq_index == (int)(long)ifindex;
}
static int masq_device_event(struct notifier_block *this,
unsigned long event,
void *ptr)
{
const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
struct net *net = dev_net(dev);
if (event == NETDEV_DOWN) {
/* Device was downed. Search entire table for
* conntracks which were associated with that device,
* and forget them.
*/
NF_CT_ASSERT(dev->ifindex != 0);
nf_ct_iterate_cleanup(net, device_cmp,
(void *)(long)dev->ifindex, 0, 0);
}
return NOTIFY_DONE;
}
static int masq_inet_event(struct notifier_block *this,
unsigned long event,
void *ptr)
{
struct in_device *idev = ((struct in_ifaddr *)ptr)->ifa_dev;
struct netdev_notifier_info info;
/* The masq_dev_notifier will catch the case of the device going
* down. So if the inetdev is dead and being destroyed we have
* no work to do. Otherwise this is an individual address removal
* and we have to perform the flush.
*/
if (idev->dead)
return NOTIFY_DONE;
netdev_notifier_info_init(&info, idev->dev);
return masq_device_event(this, event, &info);
}
static struct notifier_block masq_dev_notifier = {
.notifier_call = masq_device_event,
};
static struct notifier_block masq_inet_notifier = {
.notifier_call = masq_inet_event,
};
static atomic_t masquerade_notifier_refcount = ATOMIC_INIT(0);
void nf_nat_masquerade_ipv4_register_notifier(void)
{
/* check if the notifier was already set */
if (atomic_inc_return(&masquerade_notifier_refcount) > 1)
return;
/* Register for device down reports */
register_netdevice_notifier(&masq_dev_notifier);
/* Register IP address change reports */
register_inetaddr_notifier(&masq_inet_notifier);
}
EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_register_notifier);
void nf_nat_masquerade_ipv4_unregister_notifier(void)
{
/* check if the notifier still has clients */
if (atomic_dec_return(&masquerade_notifier_refcount) > 0)
return;
unregister_netdevice_notifier(&masq_dev_notifier);
unregister_inetaddr_notifier(&masq_inet_notifier);
}
EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_unregister_notifier);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
|