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/* (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/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_range2 *range,
const struct net_device *out)
{
struct nf_conn *ct;
struct nf_conn_nat *nat;
enum ip_conntrack_info ctinfo;
struct nf_nat_range2 newrange;
const struct rtable *rt;
__be32 newsrc, nh;
WARN_ON(hooknum != NF_INET_POST_ROUTING);
ct = nf_ct_get(skb, &ctinfo);
WARN_ON(!(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 = nf_ct_nat_ext_add(ct);
if (nat)
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.
*/
WARN_ON(dev->ifindex == 0);
nf_ct_iterate_cleanup_net(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);
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