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/*
* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
*
* 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.
*
* Based on Rusty Russell's IPv6 MASQUERADE target. Development of IPv6
* NAT funded by Astaro.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/atomic.h>
#include <linux/netdevice.h>
#include <linux/ipv6.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>
#include <net/netfilter/nf_nat.h>
#include <net/addrconf.h>
#include <net/ipv6.h>
#include <net/netfilter/ipv6/nf_nat_masquerade.h>
#define MAX_WORK_COUNT 16
static atomic_t v6_worker_count;
unsigned int
nf_nat_masquerade_ipv6(struct sk_buff *skb, const struct nf_nat_range *range,
const struct net_device *out)
{
enum ip_conntrack_info ctinfo;
struct nf_conn_nat *nat;
struct in6_addr src;
struct nf_conn *ct;
struct nf_nat_range newrange;
ct = nf_ct_get(skb, &ctinfo);
WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
ctinfo == IP_CT_RELATED_REPLY)));
if (ipv6_dev_get_saddr(nf_ct_net(ct), out,
&ipv6_hdr(skb)->daddr, 0, &src) < 0)
return NF_DROP;
nat = nf_ct_nat_ext_add(ct);
if (nat)
nat->masq_index = out->ifindex;
newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
newrange.min_addr.in6 = src;
newrange.max_addr.in6 = src;
newrange.min_proto = range->min_proto;
newrange.max_proto = range->max_proto;
return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
}
EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6);
static int device_cmp(struct nf_conn *ct, void *ifindex)
{
const struct nf_conn_nat *nat = nfct_nat(ct);
if (!nat)
return 0;
if (nf_ct_l3num(ct) != NFPROTO_IPV6)
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)
nf_ct_iterate_cleanup_net(net, device_cmp,
(void *)(long)dev->ifindex, 0, 0);
return NOTIFY_DONE;
}
static struct notifier_block masq_dev_notifier = {
.notifier_call = masq_device_event,
};
struct masq_dev_work {
struct work_struct work;
struct net *net;
struct in6_addr addr;
int ifindex;
};
static int inet_cmp(struct nf_conn *ct, void *work)
{
struct masq_dev_work *w = (struct masq_dev_work *)work;
struct nf_conntrack_tuple *tuple;
if (!device_cmp(ct, (void *)(long)w->ifindex))
return 0;
tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
return ipv6_addr_equal(&w->addr, &tuple->dst.u3.in6);
}
static void iterate_cleanup_work(struct work_struct *work)
{
struct masq_dev_work *w;
w = container_of(work, struct masq_dev_work, work);
nf_ct_iterate_cleanup_net(w->net, inet_cmp, (void *)w, 0, 0);
put_net(w->net);
kfree(w);
atomic_dec(&v6_worker_count);
module_put(THIS_MODULE);
}
/* ipv6 inet notifier is an atomic notifier, i.e. we cannot
* schedule.
*
* Unfortunately, nf_ct_iterate_cleanup_net can run for a long
* time if there are lots of conntracks and the system
* handles high softirq load, so it frequently calls cond_resched
* while iterating the conntrack table.
*
* So we defer nf_ct_iterate_cleanup_net walk to the system workqueue.
*
* As we can have 'a lot' of inet_events (depending on amount
* of ipv6 addresses being deleted), we also need to add an upper
* limit to the number of queued work items.
*/
static int masq_inet_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
struct inet6_ifaddr *ifa = ptr;
const struct net_device *dev;
struct masq_dev_work *w;
struct net *net;
if (event != NETDEV_DOWN ||
atomic_read(&v6_worker_count) >= MAX_WORK_COUNT)
return NOTIFY_DONE;
dev = ifa->idev->dev;
net = maybe_get_net(dev_net(dev));
if (!net)
return NOTIFY_DONE;
if (!try_module_get(THIS_MODULE))
goto err_module;
w = kmalloc(sizeof(*w), GFP_ATOMIC);
if (w) {
atomic_inc(&v6_worker_count);
INIT_WORK(&w->work, iterate_cleanup_work);
w->ifindex = dev->ifindex;
w->net = net;
w->addr = ifa->addr;
schedule_work(&w->work);
return NOTIFY_DONE;
}
module_put(THIS_MODULE);
err_module:
put_net(net);
return NOTIFY_DONE;
}
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_ipv6_register_notifier(void)
{
/* check if the notifier is already set */
if (atomic_inc_return(&masquerade_notifier_refcount) > 1)
return;
register_netdevice_notifier(&masq_dev_notifier);
register_inet6addr_notifier(&masq_inet_notifier);
}
EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_register_notifier);
void nf_nat_masquerade_ipv6_unregister_notifier(void)
{
/* check if the notifier still has clients */
if (atomic_dec_return(&masquerade_notifier_refcount) > 0)
return;
unregister_inet6addr_notifier(&masq_inet_notifier);
unregister_netdevice_notifier(&masq_dev_notifier);
}
EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_unregister_notifier);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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