net/ipv6/anycast.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *	Anycast support for IPv6
  *	Linux INET6 implementation
  *
  *	Authors:
  *	David L Stevens (dlstevens@us.ibm.com)
  *
  *	based heavily on net/ipv6/mcast.c
  */

 #include <linux/capability.h>
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/types.h>
 #include <linux/random.h>
 #include <linux/string.h>
 #include <linux/socket.h>
 #include <linux/sockios.h>
 #include <linux/net.h>
 #include <linux/in6.h>
 #include <linux/netdevice.h>
 #include <linux/if_arp.h>
 #include <linux/route.h>
 #include <linux/init.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>

 #include <net/net_namespace.h>
 #include <net/sock.h>
 #include <net/snmp.h>

 #include <net/ipv6.h>
 #include <net/protocol.h>
 #include <net/if_inet6.h>
 #include <net/ndisc.h>
 #include <net/addrconf.h>
 #include <net/ip6_route.h>

 #include <net/checksum.h>

 #define IN6_ADDR_HSIZE_SHIFT	8
 #define IN6_ADDR_HSIZE		BIT(IN6_ADDR_HSIZE_SHIFT)
 /*	anycast address hash table
  */
 static struct hlist_head inet6_acaddr_lst[IN6_ADDR_HSIZE];
 static DEFINE_SPINLOCK(acaddr_hash_lock);

 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr);

 static u32 inet6_acaddr_hash(struct net *net, const struct in6_addr *addr)
 {
 	u32 val = ipv6_addr_hash(addr) ^ net_hash_mix(net);

 	return hash_32(val, IN6_ADDR_HSIZE_SHIFT);
 }

 /*
  *	socket join an anycast group
  */

 int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct net_device *dev = NULL;
 	struct inet6_dev *idev;
 	struct ipv6_ac_socklist *pac;
 	struct net *net = sock_net(sk);
 	int	ishost = !net->ipv6.devconf_all->forwarding;
 	int	err = 0;

 	ASSERT_RTNL();

 	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 	if (ipv6_addr_is_multicast(addr))
 		return -EINVAL;

 	if (ifindex)
 		dev = __dev_get_by_index(net, ifindex);

 	if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE))
 		return -EINVAL;

 	pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
 	if (!pac)
 		return -ENOMEM;
 	pac->acl_next = NULL;
 	pac->acl_addr = *addr;

 	if (ifindex == 0) {
 		struct rt6_info *rt;

 		rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
 		if (rt) {
 			dev = rt->dst.dev;
 			ip6_rt_put(rt);
 		} else if (ishost) {
 			err = -EADDRNOTAVAIL;
 			goto error;
 		} else {
 			/* router, no matching interface: just pick one */
 			dev = __dev_get_by_flags(net, IFF_UP,
 						 IFF_UP | IFF_LOOPBACK);
 		}
 	}

 	if (!dev) {
 		err = -ENODEV;
 		goto error;
 	}

 	idev = __in6_dev_get(dev);
 	if (!idev) {
 		if (ifindex)
 			err = -ENODEV;
 		else
 			err = -EADDRNOTAVAIL;
 		goto error;
 	}
 	/* reset ishost, now that we have a specific device */
 	ishost = !idev->cnf.forwarding;

 	pac->acl_ifindex = dev->ifindex;

 	/* XXX
 	 * For hosts, allow link-local or matching prefix anycasts.
 	 * This obviates the need for propagating anycast routes while
 	 * still allowing some non-router anycast participation.
 	 */
 	if (!ipv6_chk_prefix(addr, dev)) {
 		if (ishost)
 			err = -EADDRNOTAVAIL;
 		if (err)
 			goto error;
 	}

 	err = __ipv6_dev_ac_inc(idev, addr);
 	if (!err) {
 		pac->acl_next = np->ipv6_ac_list;
 		np->ipv6_ac_list = pac;
 		pac = NULL;
 	}

 error:
 	if (pac)
 		sock_kfree_s(sk, pac, sizeof(*pac));
 	return err;
 }

 /*
  *	socket leave an anycast group
  */
 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct net_device *dev;
 	struct ipv6_ac_socklist *pac, *prev_pac;
 	struct net *net = sock_net(sk);

 	ASSERT_RTNL();

 	prev_pac = NULL;
 	for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 		if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 		     ipv6_addr_equal(&pac->acl_addr, addr))
 			break;
 		prev_pac = pac;
 	}
 	if (!pac)
 		return -ENOENT;
 	if (prev_pac)
 		prev_pac->acl_next = pac->acl_next;
 	else
 		np->ipv6_ac_list = pac->acl_next;

 	dev = __dev_get_by_index(net, pac->acl_ifindex);
 	if (dev)
 		ipv6_dev_ac_dec(dev, &pac->acl_addr);

 	sock_kfree_s(sk, pac, sizeof(*pac));
 	return 0;
 }

 void ipv6_sock_ac_close(struct sock *sk)
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct net_device *dev = NULL;
 	struct ipv6_ac_socklist *pac;
 	struct net *net = sock_net(sk);
 	int	prev_index;

 	if (!np->ipv6_ac_list)
 		return;

 	rtnl_lock();
 	pac = np->ipv6_ac_list;
 	np->ipv6_ac_list = NULL;

 	prev_index = 0;
 	while (pac) {
 		struct ipv6_ac_socklist *next = pac->acl_next;

 		if (pac->acl_ifindex != prev_index) {
 			dev = __dev_get_by_index(net, pac->acl_ifindex);
 			prev_index = pac->acl_ifindex;
 		}
 		if (dev)
 			ipv6_dev_ac_dec(dev, &pac->acl_addr);
 		sock_kfree_s(sk, pac, sizeof(*pac));
 		pac = next;
 	}
 	rtnl_unlock();
 }

 static void ipv6_add_acaddr_hash(struct net *net, struct ifacaddr6 *aca)
 {
 	unsigned int hash = inet6_acaddr_hash(net, &aca->aca_addr);

 	spin_lock(&acaddr_hash_lock);
 	hlist_add_head_rcu(&aca->aca_addr_lst, &inet6_acaddr_lst[hash]);
 	spin_unlock(&acaddr_hash_lock);
 }

 static void ipv6_del_acaddr_hash(struct ifacaddr6 *aca)
 {
 	spin_lock(&acaddr_hash_lock);
 	hlist_del_init_rcu(&aca->aca_addr_lst);
 	spin_unlock(&acaddr_hash_lock);
 }

 static void aca_get(struct ifacaddr6 *aca)
 {
 	refcount_inc(&aca->aca_refcnt);
 }

 static void aca_free_rcu(struct rcu_head *h)
 {
 	struct ifacaddr6 *aca = container_of(h, struct ifacaddr6, rcu);

 	fib6_info_release(aca->aca_rt);
 	kfree(aca);
 }

 static void aca_put(struct ifacaddr6 *ac)
 {
 	if (refcount_dec_and_test(&ac->aca_refcnt)) {
 		call_rcu(&ac->rcu, aca_free_rcu);
 	}
 }

 static struct ifacaddr6 *aca_alloc(struct fib6_info *f6i,
 				   const struct in6_addr *addr)
 {
 	struct ifacaddr6 *aca;

 	aca = kzalloc(sizeof(*aca), GFP_ATOMIC);
 	if (!aca)
 		return NULL;

 	aca->aca_addr = *addr;
 	fib6_info_hold(f6i);
 	aca->aca_rt = f6i;
 	INIT_HLIST_NODE(&aca->aca_addr_lst);
 	aca->aca_users = 1;
 	/* aca_tstamp should be updated upon changes */
 	aca->aca_cstamp = aca->aca_tstamp = jiffies;
 	refcount_set(&aca->aca_refcnt, 1);

 	return aca;
 }

 /*
  *	device anycast group inc (add if not found)
  */
 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr)
 {
 	struct ifacaddr6 *aca;
 	struct fib6_info *f6i;
 	struct net *net;
 	int err;

 	ASSERT_RTNL();

 	write_lock_bh(&idev->lock);
 	if (idev->dead) {
 		err = -ENODEV;
 		goto out;
 	}

 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 		if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 			aca->aca_users++;
 			err = 0;
 			goto out;
 		}
 	}

 	net = dev_net(idev->dev);
 	f6i = addrconf_f6i_alloc(net, idev, addr, true, GFP_ATOMIC);
 	if (IS_ERR(f6i)) {
 		err = PTR_ERR(f6i);
 		goto out;
 	}
 	aca = aca_alloc(f6i, addr);
 	if (!aca) {
 		fib6_info_release(f6i);
 		err = -ENOMEM;
 		goto out;
 	}

 	aca->aca_next = idev->ac_list;
 	idev->ac_list = aca;

 	/* Hold this for addrconf_join_solict() below before we unlock,
 	 * it is already exposed via idev->ac_list.
 	 */
 	aca_get(aca);
 	write_unlock_bh(&idev->lock);

 	ipv6_add_acaddr_hash(net, aca);

 	ip6_ins_rt(net, f6i);

 	addrconf_join_solict(idev->dev, &aca->aca_addr);

 	aca_put(aca);
 	return 0;
 out:
 	write_unlock_bh(&idev->lock);
 	return err;
 }

 /*
  *	device anycast group decrement
  */
 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
 {
 	struct ifacaddr6 *aca, *prev_aca;

 	ASSERT_RTNL();

 	write_lock_bh(&idev->lock);
 	prev_aca = NULL;
 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 		if (ipv6_addr_equal(&aca->aca_addr, addr))
 			break;
 		prev_aca = aca;
 	}
 	if (!aca) {
 		write_unlock_bh(&idev->lock);
 		return -ENOENT;
 	}
 	if (--aca->aca_users > 0) {
 		write_unlock_bh(&idev->lock);
 		return 0;
 	}
 	if (prev_aca)
 		prev_aca->aca_next = aca->aca_next;
 	else
 		idev->ac_list = aca->aca_next;
 	write_unlock_bh(&idev->lock);
 	ipv6_del_acaddr_hash(aca);
 	addrconf_leave_solict(idev, &aca->aca_addr);

 	ip6_del_rt(dev_net(idev->dev), aca->aca_rt);

 	aca_put(aca);
 	return 0;
 }

 /* called with rtnl_lock() */
 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
 {
 	struct inet6_dev *idev = __in6_dev_get(dev);

 	if (!idev)
 		return -ENODEV;
 	return __ipv6_dev_ac_dec(idev, addr);
 }

 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
 {
 	struct ifacaddr6 *aca;

 	write_lock_bh(&idev->lock);
 	while ((aca = idev->ac_list) != NULL) {
 		idev->ac_list = aca->aca_next;
 		write_unlock_bh(&idev->lock);

 		ipv6_del_acaddr_hash(aca);

 		addrconf_leave_solict(idev, &aca->aca_addr);

 		ip6_del_rt(dev_net(idev->dev), aca->aca_rt);

 		aca_put(aca);

 		write_lock_bh(&idev->lock);
 	}
 	write_unlock_bh(&idev->lock);
 }

 /*
  *	check if the interface has this anycast address
  *	called with rcu_read_lock()
  */
 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
 {
 	struct inet6_dev *idev;
 	struct ifacaddr6 *aca;

 	idev = __in6_dev_get(dev);
 	if (idev) {
 		read_lock_bh(&idev->lock);
 		for (aca = idev->ac_list; aca; aca = aca->aca_next)
 			if (ipv6_addr_equal(&aca->aca_addr, addr))
 				break;
 		read_unlock_bh(&idev->lock);
 		return aca != NULL;
 	}
 	return false;
 }

 /*
  *	check if given interface (or any, if dev==0) has this anycast address
  */
 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 			 const struct in6_addr *addr)
 {
 	struct net_device *nh_dev;
 	struct ifacaddr6 *aca;
 	bool found = false;

 	rcu_read_lock();
 	if (dev)
 		found = ipv6_chk_acast_dev(dev, addr);
 	else {
 		unsigned int hash = inet6_acaddr_hash(net, addr);

 		hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash],
 					 aca_addr_lst) {
 			nh_dev = fib6_info_nh_dev(aca->aca_rt);
 			if (!nh_dev || !net_eq(dev_net(nh_dev), net))
 				continue;
 			if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 				found = true;
 				break;
 			}
 		}
 	}
 	rcu_read_unlock();
 	return found;
 }

 /*	check if this anycast address is link-local on given interface or
  *	is global
  */
 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
 			     const struct in6_addr *addr)
 {
 	return ipv6_chk_acast_addr(net,
 				   (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
 				    dev : NULL),
 				   addr);
 }

 #ifdef CONFIG_PROC_FS
 struct ac6_iter_state {
 	struct seq_net_private p;
 	struct net_device *dev;
 	struct inet6_dev *idev;
 };

 #define ac6_seq_private(seq)	((struct ac6_iter_state *)(seq)->private)

 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 {
 	struct ifacaddr6 *im = NULL;
 	struct ac6_iter_state *state = ac6_seq_private(seq);
 	struct net *net = seq_file_net(seq);

 	state->idev = NULL;
 	for_each_netdev_rcu(net, state->dev) {
 		struct inet6_dev *idev;
 		idev = __in6_dev_get(state->dev);
 		if (!idev)
 			continue;
 		read_lock_bh(&idev->lock);
 		im = idev->ac_list;
 		if (im) {
 			state->idev = idev;
 			break;
 		}
 		read_unlock_bh(&idev->lock);
 	}
 	return im;
 }

 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 {
 	struct ac6_iter_state *state = ac6_seq_private(seq);

 	im = im->aca_next;
 	while (!im) {
 		if (likely(state->idev != NULL))
 			read_unlock_bh(&state->idev->lock);

 		state->dev = next_net_device_rcu(state->dev);
 		if (!state->dev) {
 			state->idev = NULL;
 			break;
 		}
 		state->idev = __in6_dev_get(state->dev);
 		if (!state->idev)
 			continue;
 		read_lock_bh(&state->idev->lock);
 		im = state->idev->ac_list;
 	}
 	return im;
 }

 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 {
 	struct ifacaddr6 *im = ac6_get_first(seq);
 	if (im)
 		while (pos && (im = ac6_get_next(seq, im)) != NULL)
 			--pos;
 	return pos ? NULL : im;
 }

 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 	__acquires(RCU)
 {
 	rcu_read_lock();
 	return ac6_get_idx(seq, *pos);
 }

 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
 	struct ifacaddr6 *im = ac6_get_next(seq, v);

 	++*pos;
 	return im;
 }

 static void ac6_seq_stop(struct seq_file *seq, void *v)
 	__releases(RCU)
 {
 	struct ac6_iter_state *state = ac6_seq_private(seq);

 	if (likely(state->idev != NULL)) {
 		read_unlock_bh(&state->idev->lock);
 		state->idev = NULL;
 	}
 	rcu_read_unlock();
 }

 static int ac6_seq_show(struct seq_file *seq, void *v)
 {
 	struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 	struct ac6_iter_state *state = ac6_seq_private(seq);

 	seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 		   state->dev->ifindex, state->dev->name,
 		   &im->aca_addr, im->aca_users);
 	return 0;
 }

 static const struct seq_operations ac6_seq_ops = {
 	.start	=	ac6_seq_start,
 	.next	=	ac6_seq_next,
 	.stop	=	ac6_seq_stop,
 	.show	=	ac6_seq_show,
 };

 int __net_init ac6_proc_init(struct net *net)
 {
 	if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops,
 			sizeof(struct ac6_iter_state)))
 		return -ENOMEM;

 	return 0;
 }

 void ac6_proc_exit(struct net *net)
 {
 	remove_proc_entry("anycast6", net->proc_net);
 }
 #endif

 /*	Init / cleanup code
  */
 int __init ipv6_anycast_init(void)
 {
 	int i;

 	for (i = 0; i < IN6_ADDR_HSIZE; i++)
 		INIT_HLIST_HEAD(&inet6_acaddr_lst[i]);
 	return 0;
 }

 void ipv6_anycast_cleanup(void)
 {
 	int i;

 	spin_lock(&acaddr_hash_lock);
 	for (i = 0; i < IN6_ADDR_HSIZE; i++)
 		WARN_ON(!hlist_empty(&inet6_acaddr_lst[i]));
 	spin_unlock(&acaddr_hash_lock);
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Anycast support for IPv6
	* Linux INET6 implementation
	*
	* Authors:
	* David L Stevens (dlstevens@us.ibm.com)
	*
	* based heavily on net/ipv6/mcast.c
	*/

	#include <linux/capability.h>
	#include <linux/module.h>
	#include <linux/errno.h>
	#include <linux/types.h>
	#include <linux/random.h>
	#include <linux/string.h>
	#include <linux/socket.h>
	#include <linux/sockios.h>
	#include <linux/net.h>
	#include <linux/in6.h>
	#include <linux/netdevice.h>
	#include <linux/if_arp.h>
	#include <linux/route.h>
	#include <linux/init.h>
	#include <linux/proc_fs.h>
	#include <linux/seq_file.h>
	#include <linux/slab.h>

	#include <net/net_namespace.h>
	#include <net/sock.h>
	#include <net/snmp.h>

	#include <net/ipv6.h>
	#include <net/protocol.h>
	#include <net/if_inet6.h>
	#include <net/ndisc.h>
	#include <net/addrconf.h>
	#include <net/ip6_route.h>

	#include <net/checksum.h>

	#define IN6_ADDR_HSIZE_SHIFT 8
	#define IN6_ADDR_HSIZE BIT(IN6_ADDR_HSIZE_SHIFT)
	/* anycast address hash table
	*/
	static struct hlist_head inet6_acaddr_lst[IN6_ADDR_HSIZE];
	static DEFINE_SPINLOCK(acaddr_hash_lock);

	static int ipv6_dev_ac_dec(struct net_device dev, const struct in6_addr addr);

	static u32 inet6_acaddr_hash(struct net net, const struct in6_addr addr)
	{
	u32 val = ipv6_addr_hash(addr) ^ net_hash_mix(net);

	return hash_32(val, IN6_ADDR_HSIZE_SHIFT);
	}

	/*
	* socket join an anycast group
	*/

	int ipv6_sock_ac_join(struct sock sk, int ifindex, const struct in6_addr addr)
	{
	struct ipv6_pinfo *np = inet6_sk(sk);
	struct net_device *dev = NULL;
	struct inet6_dev *idev;
	struct ipv6_ac_socklist *pac;
	struct net *net = sock_net(sk);
	int ishost = !net->ipv6.devconf_all->forwarding;
	int err = 0;

	ASSERT_RTNL();

	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
	return -EPERM;
	if (ipv6_addr_is_multicast(addr))
	return -EINVAL;

	if (ifindex)
	dev = __dev_get_by_index(net, ifindex);

	if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE))
	return -EINVAL;

	pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
	if (!pac)
	return -ENOMEM;
	pac->acl_next = NULL;
	pac->acl_addr = *addr;

	if (ifindex == 0) {
	struct rt6_info *rt;

	rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
	if (rt) {
	dev = rt->dst.dev;
	ip6_rt_put(rt);
	} else if (ishost) {
	err = -EADDRNOTAVAIL;
	goto error;
	} else {
	/* router, no matching interface: just pick one */
	dev = __dev_get_by_flags(net, IFF_UP,
	IFF_UP \| IFF_LOOPBACK);
	}
	}

	if (!dev) {
	err = -ENODEV;
	goto error;
	}

	idev = __in6_dev_get(dev);
	if (!idev) {
	if (ifindex)
	err = -ENODEV;
	else
	err = -EADDRNOTAVAIL;
	goto error;
	}
	/* reset ishost, now that we have a specific device */
	ishost = !idev->cnf.forwarding;

	pac->acl_ifindex = dev->ifindex;

	/* XXX
	* For hosts, allow link-local or matching prefix anycasts.
	* This obviates the need for propagating anycast routes while
	* still allowing some non-router anycast participation.
	*/
	if (!ipv6_chk_prefix(addr, dev)) {
	if (ishost)
	err = -EADDRNOTAVAIL;
	if (err)
	goto error;
	}

	err = __ipv6_dev_ac_inc(idev, addr);
	if (!err) {
	pac->acl_next = np->ipv6_ac_list;
	np->ipv6_ac_list = pac;
	pac = NULL;
	}

	error:
	if (pac)
	sock_kfree_s(sk, pac, sizeof(*pac));
	return err;
	}

	/*
	* socket leave an anycast group
	*/
	int ipv6_sock_ac_drop(struct sock sk, int ifindex, const struct in6_addr addr)
	{
	struct ipv6_pinfo *np = inet6_sk(sk);
	struct net_device *dev;
	struct ipv6_ac_socklist pac, prev_pac;
	struct net *net = sock_net(sk);

	ASSERT_RTNL();

	prev_pac = NULL;
	for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
	if ((ifindex == 0 \|\| pac->acl_ifindex == ifindex) &&
	ipv6_addr_equal(&pac->acl_addr, addr))
	break;
	prev_pac = pac;
	}
	if (!pac)
	return -ENOENT;
	if (prev_pac)
	prev_pac->acl_next = pac->acl_next;
	else
	np->ipv6_ac_list = pac->acl_next;

	dev = __dev_get_by_index(net, pac->acl_ifindex);
	if (dev)
	ipv6_dev_ac_dec(dev, &pac->acl_addr);

	sock_kfree_s(sk, pac, sizeof(*pac));
	return 0;
	}

	void ipv6_sock_ac_close(struct sock *sk)
	{
	struct ipv6_pinfo *np = inet6_sk(sk);
	struct net_device *dev = NULL;
	struct ipv6_ac_socklist *pac;
	struct net *net = sock_net(sk);
	int prev_index;

	if (!np->ipv6_ac_list)
	return;

	rtnl_lock();
	pac = np->ipv6_ac_list;
	np->ipv6_ac_list = NULL;

	prev_index = 0;
	while (pac) {
	struct ipv6_ac_socklist *next = pac->acl_next;

	if (pac->acl_ifindex != prev_index) {
	dev = __dev_get_by_index(net, pac->acl_ifindex);
	prev_index = pac->acl_ifindex;
	}
	if (dev)
	ipv6_dev_ac_dec(dev, &pac->acl_addr);
	sock_kfree_s(sk, pac, sizeof(*pac));
	pac = next;
	}
	rtnl_unlock();
	}

	static void ipv6_add_acaddr_hash(struct net net, struct ifacaddr6 aca)
	{
	unsigned int hash = inet6_acaddr_hash(net, &aca->aca_addr);

	spin_lock(&acaddr_hash_lock);
	hlist_add_head_rcu(&aca->aca_addr_lst, &inet6_acaddr_lst[hash]);
	spin_unlock(&acaddr_hash_lock);
	}

	static void ipv6_del_acaddr_hash(struct ifacaddr6 *aca)
	{
	spin_lock(&acaddr_hash_lock);
	hlist_del_init_rcu(&aca->aca_addr_lst);
	spin_unlock(&acaddr_hash_lock);
	}

	static void aca_get(struct ifacaddr6 *aca)
	{
	refcount_inc(&aca->aca_refcnt);
	}

	static void aca_free_rcu(struct rcu_head *h)
	{
	struct ifacaddr6 *aca = container_of(h, struct ifacaddr6, rcu);

	fib6_info_release(aca->aca_rt);
	kfree(aca);
	}

	static void aca_put(struct ifacaddr6 *ac)
	{
	if (refcount_dec_and_test(&ac->aca_refcnt)) {
	call_rcu(&ac->rcu, aca_free_rcu);
	}
	}

	static struct ifacaddr6 aca_alloc(struct fib6_info f6i,
	const struct in6_addr *addr)
	{
	struct ifacaddr6 *aca;

	aca = kzalloc(sizeof(*aca), GFP_ATOMIC);
	if (!aca)
	return NULL;

	aca->aca_addr = *addr;
	fib6_info_hold(f6i);
	aca->aca_rt = f6i;
	INIT_HLIST_NODE(&aca->aca_addr_lst);
	aca->aca_users = 1;
	/* aca_tstamp should be updated upon changes */
	aca->aca_cstamp = aca->aca_tstamp = jiffies;
	refcount_set(&aca->aca_refcnt, 1);

	return aca;
	}

	/*
	* device anycast group inc (add if not found)
	*/
	int __ipv6_dev_ac_inc(struct inet6_dev idev, const struct in6_addr addr)
	{
	struct ifacaddr6 *aca;
	struct fib6_info *f6i;
	struct net *net;
	int err;

	ASSERT_RTNL();

	write_lock_bh(&idev->lock);
	if (idev->dead) {
	err = -ENODEV;
	goto out;
	}

	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
	if (ipv6_addr_equal(&aca->aca_addr, addr)) {
	aca->aca_users++;
	err = 0;
	goto out;
	}
	}

	net = dev_net(idev->dev);
	f6i = addrconf_f6i_alloc(net, idev, addr, true, GFP_ATOMIC);
	if (IS_ERR(f6i)) {
	err = PTR_ERR(f6i);
	goto out;
	}
	aca = aca_alloc(f6i, addr);
	if (!aca) {
	fib6_info_release(f6i);
	err = -ENOMEM;
	goto out;
	}

	aca->aca_next = idev->ac_list;
	idev->ac_list = aca;

	/* Hold this for addrconf_join_solict() below before we unlock,
	* it is already exposed via idev->ac_list.
	*/
	aca_get(aca);
	write_unlock_bh(&idev->lock);

	ipv6_add_acaddr_hash(net, aca);

	ip6_ins_rt(net, f6i);

	addrconf_join_solict(idev->dev, &aca->aca_addr);

	aca_put(aca);
	return 0;
	out:
	write_unlock_bh(&idev->lock);
	return err;
	}

	/*
	* device anycast group decrement
	*/
	int __ipv6_dev_ac_dec(struct inet6_dev idev, const struct in6_addr addr)
	{
	struct ifacaddr6 aca, prev_aca;

	ASSERT_RTNL();

	write_lock_bh(&idev->lock);
	prev_aca = NULL;
	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
	if (ipv6_addr_equal(&aca->aca_addr, addr))
	break;
	prev_aca = aca;
	}
	if (!aca) {
	write_unlock_bh(&idev->lock);
	return -ENOENT;
	}
	if (--aca->aca_users > 0) {
	write_unlock_bh(&idev->lock);
	return 0;
	}
	if (prev_aca)
	prev_aca->aca_next = aca->aca_next;
	else
	idev->ac_list = aca->aca_next;
	write_unlock_bh(&idev->lock);
	ipv6_del_acaddr_hash(aca);
	addrconf_leave_solict(idev, &aca->aca_addr);

	ip6_del_rt(dev_net(idev->dev), aca->aca_rt);

	aca_put(aca);
	return 0;
	}

	/* called with rtnl_lock() */
	static int ipv6_dev_ac_dec(struct net_device dev, const struct in6_addr addr)
	{
	struct inet6_dev *idev = __in6_dev_get(dev);

	if (!idev)
	return -ENODEV;
	return __ipv6_dev_ac_dec(idev, addr);
	}

	void ipv6_ac_destroy_dev(struct inet6_dev *idev)
	{
	struct ifacaddr6 *aca;

	write_lock_bh(&idev->lock);
	while ((aca = idev->ac_list) != NULL) {
	idev->ac_list = aca->aca_next;
	write_unlock_bh(&idev->lock);

	ipv6_del_acaddr_hash(aca);

	addrconf_leave_solict(idev, &aca->aca_addr);

	ip6_del_rt(dev_net(idev->dev), aca->aca_rt);

	aca_put(aca);

	write_lock_bh(&idev->lock);
	}
	write_unlock_bh(&idev->lock);
	}

	/*
	* check if the interface has this anycast address
	* called with rcu_read_lock()
	*/
	static bool ipv6_chk_acast_dev(struct net_device dev, const struct in6_addr addr)
	{
	struct inet6_dev *idev;
	struct ifacaddr6 *aca;

	idev = __in6_dev_get(dev);
	if (idev) {
	read_lock_bh(&idev->lock);
	for (aca = idev->ac_list; aca; aca = aca->aca_next)
	if (ipv6_addr_equal(&aca->aca_addr, addr))
	break;
	read_unlock_bh(&idev->lock);
	return aca != NULL;
	}
	return false;
	}

	/*
	* check if given interface (or any, if dev==0) has this anycast address
	*/
	bool ipv6_chk_acast_addr(struct net net, struct net_device dev,
	const struct in6_addr *addr)
	{
	struct net_device *nh_dev;
	struct ifacaddr6 *aca;
	bool found = false;

	rcu_read_lock();
	if (dev)
	found = ipv6_chk_acast_dev(dev, addr);
	else {
	unsigned int hash = inet6_acaddr_hash(net, addr);

	hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash],
	aca_addr_lst) {
	nh_dev = fib6_info_nh_dev(aca->aca_rt);
	if (!nh_dev \|\| !net_eq(dev_net(nh_dev), net))
	continue;
	if (ipv6_addr_equal(&aca->aca_addr, addr)) {
	found = true;
	break;
	}
	}
	}
	rcu_read_unlock();
	return found;
	}

	/* check if this anycast address is link-local on given interface or
	* is global
	*/
	bool ipv6_chk_acast_addr_src(struct net net, struct net_device dev,
	const struct in6_addr *addr)
	{
	return ipv6_chk_acast_addr(net,
	(ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
	dev : NULL),
	addr);
	}

	#ifdef CONFIG_PROC_FS
	struct ac6_iter_state {
	struct seq_net_private p;
	struct net_device *dev;
	struct inet6_dev *idev;
	};

	#define ac6_seq_private(seq) ((struct ac6_iter_state *)(seq)->private)

	static inline struct ifacaddr6 ac6_get_first(struct seq_file seq)
	{
	struct ifacaddr6 *im = NULL;
	struct ac6_iter_state *state = ac6_seq_private(seq);
	struct net *net = seq_file_net(seq);

	state->idev = NULL;
	for_each_netdev_rcu(net, state->dev) {
	struct inet6_dev *idev;
	idev = __in6_dev_get(state->dev);
	if (!idev)
	continue;
	read_lock_bh(&idev->lock);
	im = idev->ac_list;
	if (im) {
	state->idev = idev;
	break;
	}
	read_unlock_bh(&idev->lock);
	}
	return im;
	}

	static struct ifacaddr6 ac6_get_next(struct seq_file seq, struct ifacaddr6 *im)
	{
	struct ac6_iter_state *state = ac6_seq_private(seq);

	im = im->aca_next;
	while (!im) {
	if (likely(state->idev != NULL))
	read_unlock_bh(&state->idev->lock);

	state->dev = next_net_device_rcu(state->dev);
	if (!state->dev) {
	state->idev = NULL;
	break;
	}
	state->idev = __in6_dev_get(state->dev);
	if (!state->idev)
	continue;
	read_lock_bh(&state->idev->lock);
	im = state->idev->ac_list;
	}
	return im;
	}

	static struct ifacaddr6 ac6_get_idx(struct seq_file seq, loff_t pos)
	{
	struct ifacaddr6 *im = ac6_get_first(seq);
	if (im)
	while (pos && (im = ac6_get_next(seq, im)) != NULL)
	--pos;
	return pos ? NULL : im;
	}

	static void ac6_seq_start(struct seq_file seq, loff_t *pos)
	__acquires(RCU)
	{
	rcu_read_lock();
	return ac6_get_idx(seq, *pos);
	}

	static void ac6_seq_next(struct seq_file seq, void v, loff_t pos)
	{
	struct ifacaddr6 *im = ac6_get_next(seq, v);

	++*pos;
	return im;
	}

	static void ac6_seq_stop(struct seq_file seq, void v)
	__releases(RCU)
	{
	struct ac6_iter_state *state = ac6_seq_private(seq);

	if (likely(state->idev != NULL)) {
	read_unlock_bh(&state->idev->lock);
	state->idev = NULL;
	}
	rcu_read_unlock();
	}

	static int ac6_seq_show(struct seq_file seq, void v)
	{
	struct ifacaddr6 im = (struct ifacaddr6 )v;
	struct ac6_iter_state *state = ac6_seq_private(seq);

	seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
	state->dev->ifindex, state->dev->name,
	&im->aca_addr, im->aca_users);
	return 0;
	}

	static const struct seq_operations ac6_seq_ops = {
	.start = ac6_seq_start,
	.next = ac6_seq_next,
	.stop = ac6_seq_stop,
	.show = ac6_seq_show,
	};

	int __net_init ac6_proc_init(struct net *net)
	{
	if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops,
	sizeof(struct ac6_iter_state)))
	return -ENOMEM;

	return 0;
	}

	void ac6_proc_exit(struct net *net)
	{
	remove_proc_entry("anycast6", net->proc_net);
	}
	#endif

	/* Init / cleanup code
	*/
	int __init ipv6_anycast_init(void)
	{
	int i;

	for (i = 0; i < IN6_ADDR_HSIZE; i++)
	INIT_HLIST_HEAD(&inet6_acaddr_lst[i]);
	return 0;
	}

	void ipv6_anycast_cleanup(void)
	{
	int i;

	spin_lock(&acaddr_hash_lock);
	for (i = 0; i < IN6_ADDR_HSIZE; i++)
	WARN_ON(!hlist_empty(&inet6_acaddr_lst[i]));
	spin_unlock(&acaddr_hash_lock);
	}