2017-08-10 13:25:24 +00:00
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/*
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* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Based on Rusty Russell's IPv6 MASQUERADE target. Development of IPv6
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* NAT funded by Astaro.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/atomic.h>
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#include <linux/netdevice.h>
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#include <linux/ipv6.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv6.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/addrconf.h>
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#include <net/ipv6.h>
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#include <net/netfilter/ipv6/nf_nat_masquerade.h>
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#define MAX_WORK_COUNT 16
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static atomic_t v6_worker_count;
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unsigned int
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nf_nat_masquerade_ipv6(struct sk_buff *skb, const struct nf_nat_range *range,
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const struct net_device *out)
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{
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enum ip_conntrack_info ctinfo;
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struct nf_conn_nat *nat;
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struct in6_addr src;
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struct nf_conn *ct;
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struct nf_nat_range newrange;
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ct = nf_ct_get(skb, &ctinfo);
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2017-10-03 17:33:45 +00:00
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WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
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ctinfo == IP_CT_RELATED_REPLY)));
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2017-08-10 13:25:24 +00:00
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if (ipv6_dev_get_saddr(nf_ct_net(ct), out,
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&ipv6_hdr(skb)->daddr, 0, &src) < 0)
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return NF_DROP;
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nat = nf_ct_nat_ext_add(ct);
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if (nat)
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nat->masq_index = out->ifindex;
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newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
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newrange.min_addr.in6 = src;
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newrange.max_addr.in6 = src;
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newrange.min_proto = range->min_proto;
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newrange.max_proto = range->max_proto;
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return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
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}
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EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6);
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static int device_cmp(struct nf_conn *ct, void *ifindex)
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{
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const struct nf_conn_nat *nat = nfct_nat(ct);
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if (!nat)
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return 0;
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if (nf_ct_l3num(ct) != NFPROTO_IPV6)
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return 0;
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return nat->masq_index == (int)(long)ifindex;
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}
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static int masq_device_event(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
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struct net *net = dev_net(dev);
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if (event == NETDEV_DOWN)
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2017-09-05 02:31:27 +00:00
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nf_ct_iterate_cleanup_net(net, device_cmp,
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(void *)(long)dev->ifindex, 0, 0);
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2017-08-10 13:25:24 +00:00
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return NOTIFY_DONE;
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}
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static struct notifier_block masq_dev_notifier = {
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.notifier_call = masq_device_event,
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};
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struct masq_dev_work {
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struct work_struct work;
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struct net *net;
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int ifindex;
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};
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static void iterate_cleanup_work(struct work_struct *work)
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{
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struct masq_dev_work *w;
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long index;
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w = container_of(work, struct masq_dev_work, work);
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index = w->ifindex;
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2017-09-05 02:31:27 +00:00
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nf_ct_iterate_cleanup_net(w->net, device_cmp, (void *)index, 0, 0);
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2017-08-10 13:25:24 +00:00
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put_net(w->net);
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kfree(w);
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atomic_dec(&v6_worker_count);
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module_put(THIS_MODULE);
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}
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/* ipv6 inet notifier is an atomic notifier, i.e. we cannot
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* schedule.
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*
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2017-09-05 02:31:27 +00:00
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* Unfortunately, nf_ct_iterate_cleanup_net can run for a long
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2017-08-10 13:25:24 +00:00
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* time if there are lots of conntracks and the system
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* handles high softirq load, so it frequently calls cond_resched
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* while iterating the conntrack table.
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*
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2017-09-05 02:31:27 +00:00
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* So we defer nf_ct_iterate_cleanup_net walk to the system workqueue.
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2017-08-10 13:25:24 +00:00
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*
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* As we can have 'a lot' of inet_events (depending on amount
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* of ipv6 addresses being deleted), we also need to add an upper
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* limit to the number of queued work items.
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*/
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static int masq_inet_event(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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struct inet6_ifaddr *ifa = ptr;
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const struct net_device *dev;
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struct masq_dev_work *w;
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struct net *net;
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if (event != NETDEV_DOWN ||
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atomic_read(&v6_worker_count) >= MAX_WORK_COUNT)
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return NOTIFY_DONE;
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dev = ifa->idev->dev;
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net = maybe_get_net(dev_net(dev));
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if (!net)
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return NOTIFY_DONE;
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if (!try_module_get(THIS_MODULE))
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goto err_module;
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w = kmalloc(sizeof(*w), GFP_ATOMIC);
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if (w) {
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atomic_inc(&v6_worker_count);
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INIT_WORK(&w->work, iterate_cleanup_work);
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w->ifindex = dev->ifindex;
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w->net = net;
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schedule_work(&w->work);
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return NOTIFY_DONE;
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}
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module_put(THIS_MODULE);
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err_module:
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put_net(net);
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return NOTIFY_DONE;
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}
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static struct notifier_block masq_inet_notifier = {
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.notifier_call = masq_inet_event,
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};
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static atomic_t masquerade_notifier_refcount = ATOMIC_INIT(0);
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void nf_nat_masquerade_ipv6_register_notifier(void)
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{
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/* check if the notifier is already set */
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if (atomic_inc_return(&masquerade_notifier_refcount) > 1)
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return;
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register_netdevice_notifier(&masq_dev_notifier);
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register_inet6addr_notifier(&masq_inet_notifier);
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}
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EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_register_notifier);
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void nf_nat_masquerade_ipv6_unregister_notifier(void)
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{
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/* check if the notifier still has clients */
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if (atomic_dec_return(&masquerade_notifier_refcount) > 0)
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return;
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unregister_inet6addr_notifier(&masq_inet_notifier);
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unregister_netdevice_notifier(&masq_dev_notifier);
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}
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EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_unregister_notifier);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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