// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *	NET3	IP device support routines.
   *

   *	Derived from the IP parts of dev.c 1.0.19

   * 		Authors:	Ross Biro

   *				Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
   *				Mark Evans, <evansmp@uhura.aston.ac.uk>
   *
   *	Additional Authors:
   *		Alan Cox, <gw4pts@gw4pts.ampr.org>
   *		Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   *
   *	Changes:
   *		Alexey Kuznetsov:	pa_* fields are replaced with ifaddr
   *					lists.
   *		Cyrus Durgin:		updated for kmod
   *		Matthias Andree:	in devinet_ioctl, compare label and
   *					address (4.4BSD alias style support),
   *					fall back to comparing just the label
   *					if no match found.
   */

  #include <linux/uaccess.h>

  #include <linux/bitops.h>

  #include <linux/capability.h>

  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/sched/signal.h>

  #include <linux/string.h>
  #include <linux/mm.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/in.h>
  #include <linux/errno.h>
  #include <linux/interrupt.h>

  #include <linux/if_addr.h>

  #include <linux/if_ether.h>
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include <linux/etherdevice.h>
  #include <linux/skbuff.h>

  #include <linux/init.h>
  #include <linux/notifier.h>
  #include <linux/inetdevice.h>
  #include <linux/igmp.h>

  #include <linux/slab.h>

  #include <linux/hash.h>

  #ifdef CONFIG_SYSCTL
  #include <linux/sysctl.h>
  #endif
  #include <linux/kmod.h>

  #include <linux/netconf.h>

  #include <net/arp.h>

  #include <net/ip.h>
  #include <net/route.h>
  #include <net/ip_fib.h>

  #include <net/rtnetlink.h>

  #include <net/net_namespace.h>

  #include <net/addrconf.h>

  #define IPV6ONLY_FLAGS	\
  		(IFA_F_NODAD | IFA_F_OPTIMISTIC | IFA_F_DADFAILED | \
  		 IFA_F_HOMEADDRESS | IFA_F_TENTATIVE | \
  		 IFA_F_MANAGETEMPADDR | IFA_F_STABLE_PRIVACY)

  static struct ipv4_devconf ipv4_devconf = {

  	.data = {

  		[IPV4_DEVCONF_ACCEPT_REDIRECTS - 1] = 1,
  		[IPV4_DEVCONF_SEND_REDIRECTS - 1] = 1,
  		[IPV4_DEVCONF_SECURE_REDIRECTS - 1] = 1,
  		[IPV4_DEVCONF_SHARED_MEDIA - 1] = 1,

  		[IPV4_DEVCONF_IGMPV2_UNSOLICITED_REPORT_INTERVAL - 1] = 10000 /*ms*/,
  		[IPV4_DEVCONF_IGMPV3_UNSOLICITED_REPORT_INTERVAL - 1] =  1000 /*ms*/,

  	},

  };
  
  static struct ipv4_devconf ipv4_devconf_dflt = {

  	.data = {

  		[IPV4_DEVCONF_ACCEPT_REDIRECTS - 1] = 1,
  		[IPV4_DEVCONF_SEND_REDIRECTS - 1] = 1,
  		[IPV4_DEVCONF_SECURE_REDIRECTS - 1] = 1,
  		[IPV4_DEVCONF_SHARED_MEDIA - 1] = 1,
  		[IPV4_DEVCONF_ACCEPT_SOURCE_ROUTE - 1] = 1,

  		[IPV4_DEVCONF_IGMPV2_UNSOLICITED_REPORT_INTERVAL - 1] = 10000 /*ms*/,
  		[IPV4_DEVCONF_IGMPV3_UNSOLICITED_REPORT_INTERVAL - 1] =  1000 /*ms*/,

  	},

  };

  #define IPV4_DEVCONF_DFLT(net, attr) \
  	IPV4_DEVCONF((*net->ipv4.devconf_dflt), attr)

  static const struct nla_policy ifa_ipv4_policy[IFA_MAX+1] = {

  	[IFA_LOCAL]     	= { .type = NLA_U32 },
  	[IFA_ADDRESS]   	= { .type = NLA_U32 },
  	[IFA_BROADCAST] 	= { .type = NLA_U32 },

  	[IFA_LABEL]     	= { .type = NLA_STRING, .len = IFNAMSIZ - 1 },

  	[IFA_CACHEINFO]		= { .len = sizeof(struct ifa_cacheinfo) },

  	[IFA_FLAGS]		= { .type = NLA_U32 },

  	[IFA_RT_PRIORITY]	= { .type = NLA_U32 },

  	[IFA_TARGET_NETNSID]	= { .type = NLA_S32 },

  };

  struct inet_fill_args {
  	u32 portid;
  	u32 seq;
  	int event;
  	unsigned int flags;
  	int netnsid;

  	int ifindex;

  };

  #define IN4_ADDR_HSIZE_SHIFT	8
  #define IN4_ADDR_HSIZE		(1U << IN4_ADDR_HSIZE_SHIFT)

  static struct hlist_head inet_addr_lst[IN4_ADDR_HSIZE];

  static u32 inet_addr_hash(const struct net *net, __be32 addr)

  {

  	u32 val = (__force u32) addr ^ net_hash_mix(net);

  	return hash_32(val, IN4_ADDR_HSIZE_SHIFT);

  }
  
  static void inet_hash_insert(struct net *net, struct in_ifaddr *ifa)
  {

  	u32 hash = inet_addr_hash(net, ifa->ifa_local);

  	ASSERT_RTNL();

  	hlist_add_head_rcu(&ifa->hash, &inet_addr_lst[hash]);

  }
  
  static void inet_hash_remove(struct in_ifaddr *ifa)
  {

  	ASSERT_RTNL();

  	hlist_del_init_rcu(&ifa->hash);

  }

  /**
   * __ip_dev_find - find the first device with a given source address.
   * @net: the net namespace
   * @addr: the source address
   * @devref: if true, take a reference on the found device
   *
   * If a caller uses devref=false, it should be protected by RCU, or RTNL
   */
  struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref)
  {

  	struct net_device *result = NULL;
  	struct in_ifaddr *ifa;

  
  	rcu_read_lock();

  	ifa = inet_lookup_ifaddr_rcu(net, addr);
  	if (!ifa) {

  		struct flowi4 fl4 = { .daddr = addr };
  		struct fib_result res = { 0 };
  		struct fib_table *local;
  
  		/* Fallback to FIB local table so that communication
  		 * over loopback subnets work.
  		 */
  		local = fib_get_table(net, RT_TABLE_LOCAL);
  		if (local &&
  		    !fib_table_lookup(local, &fl4, &res, FIB_LOOKUP_NOREF) &&
  		    res.type == RTN_LOCAL)
  			result = FIB_RES_DEV(res);

  	} else {
  		result = ifa->ifa_dev->dev;

  	}

  	if (result && devref)
  		dev_hold(result);
  	rcu_read_unlock();
  	return result;
  }
  EXPORT_SYMBOL(__ip_dev_find);

  /* called under RCU lock */
  struct in_ifaddr *inet_lookup_ifaddr_rcu(struct net *net, __be32 addr)
  {
  	u32 hash = inet_addr_hash(net, addr);
  	struct in_ifaddr *ifa;
  
  	hlist_for_each_entry_rcu(ifa, &inet_addr_lst[hash], hash)
  		if (ifa->ifa_local == addr &&
  		    net_eq(dev_net(ifa->ifa_dev->dev), net))
  			return ifa;
  
  	return NULL;
  }

  static void rtmsg_ifa(int event, struct in_ifaddr *, struct nlmsghdr *, u32);

  static BLOCKING_NOTIFIER_HEAD(inetaddr_chain);

  static BLOCKING_NOTIFIER_HEAD(inetaddr_validator_chain);

  static void inet_del_ifa(struct in_device *in_dev,
  			 struct in_ifaddr __rcu **ifap,

  			 int destroy);
  #ifdef CONFIG_SYSCTL

  static int devinet_sysctl_register(struct in_device *idev);

  static void devinet_sysctl_unregister(struct in_device *idev);
  #else

  static int devinet_sysctl_register(struct in_device *idev)

  {

  	return 0;

  }

  static void devinet_sysctl_unregister(struct in_device *idev)

  {
  }

  #endif
  
  /* Locks all the inet devices. */
  
  static struct in_ifaddr *inet_alloc_ifa(void)
  {

  	return kzalloc(sizeof(struct in_ifaddr), GFP_KERNEL);

  }
  
  static void inet_rcu_free_ifa(struct rcu_head *head)
  {
  	struct in_ifaddr *ifa = container_of(head, struct in_ifaddr, rcu_head);
  	if (ifa->ifa_dev)
  		in_dev_put(ifa->ifa_dev);
  	kfree(ifa);
  }

  static void inet_free_ifa(struct in_ifaddr *ifa)

  {
  	call_rcu(&ifa->rcu_head, inet_rcu_free_ifa);
  }
  
  void in_dev_finish_destroy(struct in_device *idev)
  {
  	struct net_device *dev = idev->dev;

  	WARN_ON(idev->ifa_list);
  	WARN_ON(idev->mc_list);

  	kfree(rcu_dereference_protected(idev->mc_hash, 1));

  #ifdef NET_REFCNT_DEBUG

  	pr_debug("%s: %p=%s
  ", __func__, idev, dev ? dev->name : "NIL");

  #endif
  	dev_put(dev);
  	if (!idev->dead)

  		pr_err("Freeing alive in_device %p
  ", idev);
  	else

  		kfree(idev);

  }

  EXPORT_SYMBOL(in_dev_finish_destroy);

  static struct in_device *inetdev_init(struct net_device *dev)

  {
  	struct in_device *in_dev;

  	int err = -ENOMEM;

  
  	ASSERT_RTNL();

  	in_dev = kzalloc(sizeof(*in_dev), GFP_KERNEL);

  	if (!in_dev)
  		goto out;

  	memcpy(&in_dev->cnf, dev_net(dev)->ipv4.devconf_dflt,

  			sizeof(in_dev->cnf));

  	in_dev->cnf.sysctl = NULL;
  	in_dev->dev = dev;

  	in_dev->arp_parms = neigh_parms_alloc(dev, &arp_tbl);
  	if (!in_dev->arp_parms)

  		goto out_kfree;

  	if (IPV4_DEVCONF(in_dev->cnf, FORWARDING))
  		dev_disable_lro(dev);

  	/* Reference in_dev->dev */
  	dev_hold(dev);

  	/* Account for reference dev->ip_ptr (below) */

  	refcount_set(&in_dev->refcnt, 1);

  	err = devinet_sysctl_register(in_dev);
  	if (err) {
  		in_dev->dead = 1;

  		neigh_parms_release(&arp_tbl, in_dev->arp_parms);

  		in_dev_put(in_dev);
  		in_dev = NULL;
  		goto out;
  	}

  	ip_mc_init_dev(in_dev);
  	if (dev->flags & IFF_UP)
  		ip_mc_up(in_dev);

  	/* we can receive as soon as ip_ptr is set -- do this last */

  	rcu_assign_pointer(dev->ip_ptr, in_dev);

  out:

  	return in_dev ?: ERR_PTR(err);

  out_kfree:
  	kfree(in_dev);
  	in_dev = NULL;
  	goto out;
  }
  
  static void in_dev_rcu_put(struct rcu_head *head)
  {
  	struct in_device *idev = container_of(head, struct in_device, rcu_head);
  	in_dev_put(idev);
  }
  
  static void inetdev_destroy(struct in_device *in_dev)
  {

  	struct net_device *dev;

  	struct in_ifaddr *ifa;

  
  	ASSERT_RTNL();
  
  	dev = in_dev->dev;

  
  	in_dev->dead = 1;
  
  	ip_mc_destroy_dev(in_dev);

  	while ((ifa = rtnl_dereference(in_dev->ifa_list)) != NULL) {

  		inet_del_ifa(in_dev, &in_dev->ifa_list, 0);
  		inet_free_ifa(ifa);
  	}

  	RCU_INIT_POINTER(dev->ip_ptr, NULL);

  	devinet_sysctl_unregister(in_dev);

  	neigh_parms_release(&arp_tbl, in_dev->arp_parms);
  	arp_ifdown(dev);
  
  	call_rcu(&in_dev->rcu_head, in_dev_rcu_put);
  }

  int inet_addr_onlink(struct in_device *in_dev, __be32 a, __be32 b)

  {

  	const struct in_ifaddr *ifa;

  	rcu_read_lock();

  	in_dev_for_each_ifa_rcu(ifa, in_dev) {

  		if (inet_ifa_match(a, ifa)) {
  			if (!b || inet_ifa_match(b, ifa)) {
  				rcu_read_unlock();
  				return 1;
  			}
  		}

  	}

  	rcu_read_unlock();
  	return 0;
  }

  static void __inet_del_ifa(struct in_device *in_dev,
  			   struct in_ifaddr __rcu **ifap,
  			   int destroy, struct nlmsghdr *nlh, u32 portid)

  {

  	struct in_ifaddr *promote = NULL;

  	struct in_ifaddr *ifa, *ifa1;
  	struct in_ifaddr *last_prim;

  	struct in_ifaddr *prev_prom = NULL;
  	int do_promote = IN_DEV_PROMOTE_SECONDARIES(in_dev);

  
  	ASSERT_RTNL();

  	ifa1 = rtnl_dereference(*ifap);
  	last_prim = rtnl_dereference(in_dev->ifa_list);

  	if (in_dev->dead)
  		goto no_promotions;

  	/* 1. Deleting primary ifaddr forces deletion all secondaries

  	 * unless alias promotion is set
  	 **/

  
  	if (!(ifa1->ifa_flags & IFA_F_SECONDARY)) {

  		struct in_ifaddr __rcu **ifap1 = &ifa1->ifa_next;

  		while ((ifa = rtnl_dereference(*ifap1)) != NULL) {

  			if (!(ifa->ifa_flags & IFA_F_SECONDARY) &&

  			    ifa1->ifa_scope <= ifa->ifa_scope)
  				last_prim = ifa;

  			if (!(ifa->ifa_flags & IFA_F_SECONDARY) ||
  			    ifa1->ifa_mask != ifa->ifa_mask ||
  			    !inet_ifa_match(ifa1->ifa_address, ifa)) {
  				ifap1 = &ifa->ifa_next;

  				prev_prom = ifa;

  				continue;
  			}

  			if (!do_promote) {

  				inet_hash_remove(ifa);

  				*ifap1 = ifa->ifa_next;

  				rtmsg_ifa(RTM_DELADDR, ifa, nlh, portid);

  				blocking_notifier_call_chain(&inetaddr_chain,
  						NETDEV_DOWN, ifa);

  				inet_free_ifa(ifa);
  			} else {
  				promote = ifa;
  				break;
  			}

  		}
  	}

  	/* On promotion all secondaries from subnet are changing
  	 * the primary IP, we must remove all their routes silently
  	 * and later to add them back with new prefsrc. Do this
  	 * while all addresses are on the device list.
  	 */

  	for (ifa = promote; ifa; ifa = rtnl_dereference(ifa->ifa_next)) {

  		if (ifa1->ifa_mask == ifa->ifa_mask &&
  		    inet_ifa_match(ifa1->ifa_address, ifa))
  			fib_del_ifaddr(ifa, ifa1);
  	}

  no_promotions:

  	/* 2. Unlink it */
  
  	*ifap = ifa1->ifa_next;

  	inet_hash_remove(ifa1);

  
  	/* 3. Announce address deletion */
  
  	/* Send message first, then call notifier.
  	   At first sight, FIB update triggered by notifier
  	   will refer to already deleted ifaddr, that could confuse
  	   netlink listeners. It is not true: look, gated sees
  	   that route deleted and if it still thinks that ifaddr
  	   is valid, it will try to restore deleted routes... Grr.
  	   So that, this order is correct.
  	 */

  	rtmsg_ifa(RTM_DELADDR, ifa1, nlh, portid);

  	blocking_notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa1);

  	if (promote) {

  		struct in_ifaddr *next_sec;

  		next_sec = rtnl_dereference(promote->ifa_next);

  		if (prev_prom) {

  			struct in_ifaddr *last_sec;

  			rcu_assign_pointer(prev_prom->ifa_next, next_sec);

  
  			last_sec = rtnl_dereference(last_prim->ifa_next);

  			rcu_assign_pointer(promote->ifa_next, last_sec);
  			rcu_assign_pointer(last_prim->ifa_next, promote);

  		}

  		promote->ifa_flags &= ~IFA_F_SECONDARY;

  		rtmsg_ifa(RTM_NEWADDR, promote, nlh, portid);

  		blocking_notifier_call_chain(&inetaddr_chain,
  				NETDEV_UP, promote);

  		for (ifa = next_sec; ifa;
  		     ifa = rtnl_dereference(ifa->ifa_next)) {

  			if (ifa1->ifa_mask != ifa->ifa_mask ||
  			    !inet_ifa_match(ifa1->ifa_address, ifa))
  					continue;
  			fib_add_ifaddr(ifa);
  		}
  
  	}

  	if (destroy)

  		inet_free_ifa(ifa1);

  }

  static void inet_del_ifa(struct in_device *in_dev,
  			 struct in_ifaddr __rcu **ifap,

  			 int destroy)
  {
  	__inet_del_ifa(in_dev, ifap, destroy, NULL, 0);
  }

  static void check_lifetime(struct work_struct *work);
  
  static DECLARE_DELAYED_WORK(check_lifetime_work, check_lifetime);

  static int __inet_insert_ifa(struct in_ifaddr *ifa, struct nlmsghdr *nlh,

  			     u32 portid, struct netlink_ext_ack *extack)

  {

  	struct in_ifaddr __rcu **last_primary, **ifap;

  	struct in_device *in_dev = ifa->ifa_dev;

  	struct in_validator_info ivi;

  	struct in_ifaddr *ifa1;

  	int ret;

  
  	ASSERT_RTNL();
  
  	if (!ifa->ifa_local) {
  		inet_free_ifa(ifa);
  		return 0;
  	}
  
  	ifa->ifa_flags &= ~IFA_F_SECONDARY;
  	last_primary = &in_dev->ifa_list;

  	/* Don't set IPv6 only flags to IPv4 addresses */
  	ifa->ifa_flags &= ~IPV6ONLY_FLAGS;

  	ifap = &in_dev->ifa_list;
  	ifa1 = rtnl_dereference(*ifap);
  
  	while (ifa1) {

  		if (!(ifa1->ifa_flags & IFA_F_SECONDARY) &&
  		    ifa->ifa_scope <= ifa1->ifa_scope)
  			last_primary = &ifa1->ifa_next;
  		if (ifa1->ifa_mask == ifa->ifa_mask &&
  		    inet_ifa_match(ifa1->ifa_address, ifa)) {
  			if (ifa1->ifa_local == ifa->ifa_local) {
  				inet_free_ifa(ifa);
  				return -EEXIST;
  			}
  			if (ifa1->ifa_scope != ifa->ifa_scope) {
  				inet_free_ifa(ifa);
  				return -EINVAL;
  			}
  			ifa->ifa_flags |= IFA_F_SECONDARY;
  		}

  
  		ifap = &ifa1->ifa_next;
  		ifa1 = rtnl_dereference(*ifap);

  	}

  	/* Allow any devices that wish to register ifaddr validtors to weigh
  	 * in now, before changes are committed.  The rntl lock is serializing
  	 * access here, so the state should not change between a validator call
  	 * and a final notify on commit.  This isn't invoked on promotion under
  	 * the assumption that validators are checking the address itself, and
  	 * not the flags.
  	 */
  	ivi.ivi_addr = ifa->ifa_address;
  	ivi.ivi_dev = ifa->ifa_dev;

  	ivi.extack = extack;

  	ret = blocking_notifier_call_chain(&inetaddr_validator_chain,
  					   NETDEV_UP, &ivi);
  	ret = notifier_to_errno(ret);
  	if (ret) {
  		inet_free_ifa(ifa);
  		return ret;
  	}

  	if (!(ifa->ifa_flags & IFA_F_SECONDARY)) {

  		prandom_seed((__force u32) ifa->ifa_local);

  		ifap = last_primary;
  	}

  	rcu_assign_pointer(ifa->ifa_next, *ifap);
  	rcu_assign_pointer(*ifap, ifa);

  	inet_hash_insert(dev_net(in_dev->dev), ifa);

  	cancel_delayed_work(&check_lifetime_work);

  	queue_delayed_work(system_power_efficient_wq, &check_lifetime_work, 0);

  	/* Send message first, then call notifier.
  	   Notifier will trigger FIB update, so that
  	   listeners of netlink will know about new ifaddr */

  	rtmsg_ifa(RTM_NEWADDR, ifa, nlh, portid);

  	blocking_notifier_call_chain(&inetaddr_chain, NETDEV_UP, ifa);

  
  	return 0;
  }

  static int inet_insert_ifa(struct in_ifaddr *ifa)
  {

  	return __inet_insert_ifa(ifa, NULL, 0, NULL);

  }

  static int inet_set_ifa(struct net_device *dev, struct in_ifaddr *ifa)
  {

  	struct in_device *in_dev = __in_dev_get_rtnl(dev);

  
  	ASSERT_RTNL();
  
  	if (!in_dev) {

  		inet_free_ifa(ifa);
  		return -ENOBUFS;

  	}

  	ipv4_devconf_setall(in_dev);

  	neigh_parms_data_state_setall(in_dev->arp_parms);

  	if (ifa->ifa_dev != in_dev) {

  		WARN_ON(ifa->ifa_dev);

  		in_dev_hold(in_dev);
  		ifa->ifa_dev = in_dev;
  	}

  	if (ipv4_is_loopback(ifa->ifa_local))

  		ifa->ifa_scope = RT_SCOPE_HOST;
  	return inet_insert_ifa(ifa);
  }

  /* Caller must hold RCU or RTNL :
   * We dont take a reference on found in_device
   */

  struct in_device *inetdev_by_index(struct net *net, int ifindex)

  {
  	struct net_device *dev;
  	struct in_device *in_dev = NULL;

  
  	rcu_read_lock();
  	dev = dev_get_by_index_rcu(net, ifindex);

  	if (dev)

  		in_dev = rcu_dereference_rtnl(dev->ip_ptr);

  	rcu_read_unlock();

  	return in_dev;
  }

  EXPORT_SYMBOL(inetdev_by_index);

  
  /* Called only from RTNL semaphored context. No locks. */

  struct in_ifaddr *inet_ifa_byprefix(struct in_device *in_dev, __be32 prefix,
  				    __be32 mask)

  {

  	struct in_ifaddr *ifa;

  	ASSERT_RTNL();

  	in_dev_for_each_ifa_rtnl(ifa, in_dev) {

  		if (ifa->ifa_mask == mask && inet_ifa_match(prefix, ifa))
  			return ifa;

  	}

  	return NULL;
  }

  static int ip_mc_autojoin_config(struct net *net, bool join,
  				 const struct in_ifaddr *ifa)

  {

  #if defined(CONFIG_IP_MULTICAST)

  	struct ip_mreqn mreq = {
  		.imr_multiaddr.s_addr = ifa->ifa_address,
  		.imr_ifindex = ifa->ifa_dev->dev->ifindex,
  	};

  	struct sock *sk = net->ipv4.mc_autojoin_sk;

  	int ret;
  
  	ASSERT_RTNL();
  
  	lock_sock(sk);
  	if (join)

  		ret = ip_mc_join_group(sk, &mreq);

  	else

  		ret = ip_mc_leave_group(sk, &mreq);

  	release_sock(sk);
  
  	return ret;

  #else
  	return -EOPNOTSUPP;
  #endif

  }

  static int inet_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
  			    struct netlink_ext_ack *extack)

  {

  	struct net *net = sock_net(skb->sk);

  	struct in_ifaddr __rcu **ifap;

  	struct nlattr *tb[IFA_MAX+1];

  	struct in_device *in_dev;

  	struct ifaddrmsg *ifm;

  	struct in_ifaddr *ifa;

  	int err = -EINVAL;

  
  	ASSERT_RTNL();

  	err = nlmsg_parse_deprecated(nlh, sizeof(*ifm), tb, IFA_MAX,
  				     ifa_ipv4_policy, extack);

  	if (err < 0)
  		goto errout;
  
  	ifm = nlmsg_data(nlh);

  	in_dev = inetdev_by_index(net, ifm->ifa_index);

  	if (!in_dev) {

  		err = -ENODEV;
  		goto errout;
  	}

  	for (ifap = &in_dev->ifa_list; (ifa = rtnl_dereference(*ifap)) != NULL;

  	     ifap = &ifa->ifa_next) {

  		if (tb[IFA_LOCAL] &&

  		    ifa->ifa_local != nla_get_in_addr(tb[IFA_LOCAL]))

  			continue;
  
  		if (tb[IFA_LABEL] && nla_strcmp(tb[IFA_LABEL], ifa->ifa_label))

  			continue;

  
  		if (tb[IFA_ADDRESS] &&
  		    (ifm->ifa_prefixlen != ifa->ifa_prefixlen ||

  		    !inet_ifa_match(nla_get_in_addr(tb[IFA_ADDRESS]), ifa)))

  			continue;

  		if (ipv4_is_multicast(ifa->ifa_address))

  			ip_mc_autojoin_config(net, false, ifa);

  		__inet_del_ifa(in_dev, ifap, 1, nlh, NETLINK_CB(skb).portid);

  		return 0;
  	}

  
  	err = -EADDRNOTAVAIL;
  errout:
  	return err;

  }

  #define INFINITY_LIFE_TIME	0xFFFFFFFF
  
  static void check_lifetime(struct work_struct *work)
  {
  	unsigned long now, next, next_sec, next_sched;
  	struct in_ifaddr *ifa;

  	struct hlist_node *n;

  	int i;
  
  	now = jiffies;
  	next = round_jiffies_up(now + ADDR_CHECK_FREQUENCY);

  	for (i = 0; i < IN4_ADDR_HSIZE; i++) {

  		bool change_needed = false;
  
  		rcu_read_lock();

  		hlist_for_each_entry_rcu(ifa, &inet_addr_lst[i], hash) {

  			unsigned long age;
  
  			if (ifa->ifa_flags & IFA_F_PERMANENT)
  				continue;
  
  			/* We try to batch several events at once. */
  			age = (now - ifa->ifa_tstamp +
  			       ADDRCONF_TIMER_FUZZ_MINUS) / HZ;
  
  			if (ifa->ifa_valid_lft != INFINITY_LIFE_TIME &&
  			    age >= ifa->ifa_valid_lft) {

  				change_needed = true;

  			} else if (ifa->ifa_preferred_lft ==
  				   INFINITY_LIFE_TIME) {
  				continue;
  			} else if (age >= ifa->ifa_preferred_lft) {
  				if (time_before(ifa->ifa_tstamp +
  						ifa->ifa_valid_lft * HZ, next))
  					next = ifa->ifa_tstamp +
  					       ifa->ifa_valid_lft * HZ;

  				if (!(ifa->ifa_flags & IFA_F_DEPRECATED))
  					change_needed = true;

  			} else if (time_before(ifa->ifa_tstamp +
  					       ifa->ifa_preferred_lft * HZ,
  					       next)) {
  				next = ifa->ifa_tstamp +
  				       ifa->ifa_preferred_lft * HZ;
  			}
  		}

  		rcu_read_unlock();
  		if (!change_needed)
  			continue;
  		rtnl_lock();
  		hlist_for_each_entry_safe(ifa, n, &inet_addr_lst[i], hash) {
  			unsigned long age;
  
  			if (ifa->ifa_flags & IFA_F_PERMANENT)
  				continue;
  
  			/* We try to batch several events at once. */
  			age = (now - ifa->ifa_tstamp +
  			       ADDRCONF_TIMER_FUZZ_MINUS) / HZ;
  
  			if (ifa->ifa_valid_lft != INFINITY_LIFE_TIME &&
  			    age >= ifa->ifa_valid_lft) {

  				struct in_ifaddr __rcu **ifap;
  				struct in_ifaddr *tmp;
  
  				ifap = &ifa->ifa_dev->ifa_list;
  				tmp = rtnl_dereference(*ifap);
  				while (tmp) {

  					if (tmp == ifa) {

  						inet_del_ifa(ifa->ifa_dev,
  							     ifap, 1);
  						break;
  					}

  					ifap = &tmp->ifa_next;
  					tmp = rtnl_dereference(*ifap);

  				}
  			} else if (ifa->ifa_preferred_lft !=
  				   INFINITY_LIFE_TIME &&
  				   age >= ifa->ifa_preferred_lft &&
  				   !(ifa->ifa_flags & IFA_F_DEPRECATED)) {
  				ifa->ifa_flags |= IFA_F_DEPRECATED;
  				rtmsg_ifa(RTM_NEWADDR, ifa, NULL, 0);
  			}
  		}
  		rtnl_unlock();

  	}

  
  	next_sec = round_jiffies_up(next);
  	next_sched = next;
  
  	/* If rounded timeout is accurate enough, accept it. */
  	if (time_before(next_sec, next + ADDRCONF_TIMER_FUZZ))
  		next_sched = next_sec;
  
  	now = jiffies;
  	/* And minimum interval is ADDRCONF_TIMER_FUZZ_MAX. */
  	if (time_before(next_sched, now + ADDRCONF_TIMER_FUZZ_MAX))
  		next_sched = now + ADDRCONF_TIMER_FUZZ_MAX;

  	queue_delayed_work(system_power_efficient_wq, &check_lifetime_work,
  			next_sched - now);

  }
  
  static void set_ifa_lifetime(struct in_ifaddr *ifa, __u32 valid_lft,
  			     __u32 prefered_lft)
  {
  	unsigned long timeout;
  
  	ifa->ifa_flags &= ~(IFA_F_PERMANENT | IFA_F_DEPRECATED);
  
  	timeout = addrconf_timeout_fixup(valid_lft, HZ);
  	if (addrconf_finite_timeout(timeout))
  		ifa->ifa_valid_lft = timeout;
  	else
  		ifa->ifa_flags |= IFA_F_PERMANENT;
  
  	timeout = addrconf_timeout_fixup(prefered_lft, HZ);
  	if (addrconf_finite_timeout(timeout)) {
  		if (timeout == 0)
  			ifa->ifa_flags |= IFA_F_DEPRECATED;
  		ifa->ifa_preferred_lft = timeout;
  	}
  	ifa->ifa_tstamp = jiffies;
  	if (!ifa->ifa_cstamp)
  		ifa->ifa_cstamp = ifa->ifa_tstamp;
  }
  
  static struct in_ifaddr *rtm_to_ifaddr(struct net *net, struct nlmsghdr *nlh,

  				       __u32 *pvalid_lft, __u32 *pprefered_lft,
  				       struct netlink_ext_ack *extack)

  {

  	struct nlattr *tb[IFA_MAX+1];
  	struct in_ifaddr *ifa;
  	struct ifaddrmsg *ifm;

  	struct net_device *dev;
  	struct in_device *in_dev;

  	int err;

  	err = nlmsg_parse_deprecated(nlh, sizeof(*ifm), tb, IFA_MAX,
  				     ifa_ipv4_policy, extack);

  	if (err < 0)
  		goto errout;

  	ifm = nlmsg_data(nlh);

  	err = -EINVAL;

  	if (ifm->ifa_prefixlen > 32 || !tb[IFA_LOCAL])

  		goto errout;

  	dev = __dev_get_by_index(net, ifm->ifa_index);

  	err = -ENODEV;

  	if (!dev)

  		goto errout;

  	in_dev = __in_dev_get_rtnl(dev);

  	err = -ENOBUFS;

  	if (!in_dev)

  		goto errout;

  	ifa = inet_alloc_ifa();

  	if (!ifa)

  		/*
  		 * A potential indev allocation can be left alive, it stays
  		 * assigned to its device and is destroy with it.
  		 */

  		goto errout;

  	ipv4_devconf_setall(in_dev);

  	neigh_parms_data_state_setall(in_dev->arp_parms);

  	in_dev_hold(in_dev);

  	if (!tb[IFA_ADDRESS])

  		tb[IFA_ADDRESS] = tb[IFA_LOCAL];

  	INIT_HLIST_NODE(&ifa->hash);

  	ifa->ifa_prefixlen = ifm->ifa_prefixlen;
  	ifa->ifa_mask = inet_make_mask(ifm->ifa_prefixlen);

  	ifa->ifa_flags = tb[IFA_FLAGS] ? nla_get_u32(tb[IFA_FLAGS]) :
  					 ifm->ifa_flags;

  	ifa->ifa_scope = ifm->ifa_scope;

  	ifa->ifa_dev = in_dev;

  	ifa->ifa_local = nla_get_in_addr(tb[IFA_LOCAL]);
  	ifa->ifa_address = nla_get_in_addr(tb[IFA_ADDRESS]);

  
  	if (tb[IFA_BROADCAST])

  		ifa->ifa_broadcast = nla_get_in_addr(tb[IFA_BROADCAST]);

  	if (tb[IFA_LABEL])
  		nla_strlcpy(ifa->ifa_label, tb[IFA_LABEL], IFNAMSIZ);

  	else
  		memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);

  	if (tb[IFA_RT_PRIORITY])
  		ifa->ifa_rt_priority = nla_get_u32(tb[IFA_RT_PRIORITY]);

  	if (tb[IFA_CACHEINFO]) {
  		struct ifa_cacheinfo *ci;
  
  		ci = nla_data(tb[IFA_CACHEINFO]);
  		if (!ci->ifa_valid || ci->ifa_prefered > ci->ifa_valid) {
  			err = -EINVAL;

  			goto errout_free;

  		}
  		*pvalid_lft = ci->ifa_valid;
  		*pprefered_lft = ci->ifa_prefered;
  	}

  	return ifa;

  errout_free:
  	inet_free_ifa(ifa);

  errout:
  	return ERR_PTR(err);
  }

  static struct in_ifaddr *find_matching_ifa(struct in_ifaddr *ifa)
  {
  	struct in_device *in_dev = ifa->ifa_dev;

  	struct in_ifaddr *ifa1;

  
  	if (!ifa->ifa_local)
  		return NULL;

  	in_dev_for_each_ifa_rtnl(ifa1, in_dev) {

  		if (ifa1->ifa_mask == ifa->ifa_mask &&
  		    inet_ifa_match(ifa1->ifa_address, ifa) &&
  		    ifa1->ifa_local == ifa->ifa_local)
  			return ifa1;
  	}
  	return NULL;
  }

  static int inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
  			    struct netlink_ext_ack *extack)

  {

  	struct net *net = sock_net(skb->sk);

  	struct in_ifaddr *ifa;

  	struct in_ifaddr *ifa_existing;
  	__u32 valid_lft = INFINITY_LIFE_TIME;
  	__u32 prefered_lft = INFINITY_LIFE_TIME;

  
  	ASSERT_RTNL();

  	ifa = rtm_to_ifaddr(net, nlh, &valid_lft, &prefered_lft, extack);

  	if (IS_ERR(ifa))
  		return PTR_ERR(ifa);

  	ifa_existing = find_matching_ifa(ifa);
  	if (!ifa_existing) {
  		/* It would be best to check for !NLM_F_CREATE here but

  		 * userspace already relies on not having to provide this.

  		 */
  		set_ifa_lifetime(ifa, valid_lft, prefered_lft);

  		if (ifa->ifa_flags & IFA_F_MCAUTOJOIN) {

  			int ret = ip_mc_autojoin_config(net, true, ifa);

  
  			if (ret < 0) {
  				inet_free_ifa(ifa);
  				return ret;
  			}
  		}

  		return __inet_insert_ifa(ifa, nlh, NETLINK_CB(skb).portid,
  					 extack);

  	} else {

  		u32 new_metric = ifa->ifa_rt_priority;

  		inet_free_ifa(ifa);
  
  		if (nlh->nlmsg_flags & NLM_F_EXCL ||
  		    !(nlh->nlmsg_flags & NLM_F_REPLACE))
  			return -EEXIST;

  		ifa = ifa_existing;

  
  		if (ifa->ifa_rt_priority != new_metric) {
  			fib_modify_prefix_metric(ifa, new_metric);
  			ifa->ifa_rt_priority = new_metric;
  		}

  		set_ifa_lifetime(ifa, valid_lft, prefered_lft);

  		cancel_delayed_work(&check_lifetime_work);

  		queue_delayed_work(system_power_efficient_wq,
  				&check_lifetime_work, 0);

  		rtmsg_ifa(RTM_NEWADDR, ifa, nlh, NETLINK_CB(skb).portid);

  	}
  	return 0;

  }
  
  /*
   *	Determine a default network mask, based on the IP address.
   */

  static int inet_abc_len(__be32 addr)

  {
  	int rc = -1;	/* Something else, probably a multicast. */

  	if (ipv4_is_zeronet(addr) || ipv4_is_lbcast(addr))

  		rc = 0;

  	else {

  		__u32 haddr = ntohl(addr);

  		if (IN_CLASSA(haddr))

  			rc = 8;

  		else if (IN_CLASSB(haddr))

  			rc = 16;

  		else if (IN_CLASSC(haddr))

  			rc = 24;

  		else if (IN_CLASSE(haddr))
  			rc = 32;

  	}

  	return rc;

  }

  int devinet_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr)

  {

  	struct sockaddr_in sin_orig;

  	struct sockaddr_in *sin = (struct sockaddr_in *)&ifr->ifr_addr;

  	struct in_ifaddr __rcu **ifap = NULL;

  	struct in_device *in_dev;

  	struct in_ifaddr *ifa = NULL;
  	struct net_device *dev;
  	char *colon;
  	int ret = -EFAULT;
  	int tryaddrmatch = 0;

  	ifr->ifr_name[IFNAMSIZ - 1] = 0;

  
  	/* save original address for comparison */
  	memcpy(&sin_orig, sin, sizeof(*sin));

  	colon = strchr(ifr->ifr_name, ':');

  	if (colon)
  		*colon = 0;

  	dev_load(net, ifr->ifr_name);

  	switch (cmd) {

  	case SIOCGIFADDR:	/* Get interface address */
  	case SIOCGIFBRDADDR:	/* Get the broadcast address */
  	case SIOCGIFDSTADDR:	/* Get the destination address */
  	case SIOCGIFNETMASK:	/* Get the netmask for the interface */
  		/* Note that these ioctls will not sleep,
  		   so that we do not impose a lock.
  		   One day we will be forced to put shlock here (I mean SMP)
  		 */
  		tryaddrmatch = (sin_orig.sin_family == AF_INET);
  		memset(sin, 0, sizeof(*sin));
  		sin->sin_family = AF_INET;
  		break;
  
  	case SIOCSIFFLAGS:

  		ret = -EPERM;

  		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))

  			goto out;
  		break;
  	case SIOCSIFADDR:	/* Set interface address (and family) */
  	case SIOCSIFBRDADDR:	/* Set the broadcast address */
  	case SIOCSIFDSTADDR:	/* Set the destination address */
  	case SIOCSIFNETMASK: 	/* Set the netmask for the interface */

  		ret = -EPERM;

  		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))

  			goto out;
  		ret = -EINVAL;
  		if (sin->sin_family != AF_INET)
  			goto out;
  		break;
  	default:
  		ret = -EINVAL;
  		goto out;
  	}
  
  	rtnl_lock();
  
  	ret = -ENODEV;

  	dev = __dev_get_by_name(net, ifr->ifr_name);

  	if (!dev)

  		goto done;
  
  	if (colon)
  		*colon = ':';

  	in_dev = __in_dev_get_rtnl(dev);
  	if (in_dev) {

  		if (tryaddrmatch) {
  			/* Matthias Andree */
  			/* compare label and address (4.4BSD style) */
  			/* note: we only do this for a limited set of ioctls
  			   and only if the original address family was AF_INET.
  			   This is checked above. */

  
  			for (ifap = &in_dev->ifa_list;
  			     (ifa = rtnl_dereference(*ifap)) != NULL;

  			     ifap = &ifa->ifa_next) {

  				if (!strcmp(ifr->ifr_name, ifa->ifa_label) &&

  				    sin_orig.sin_addr.s_addr ==

  							ifa->ifa_local) {

  					break; /* found */
  				}
  			}
  		}
  		/* we didn't get a match, maybe the application is
  		   4.3BSD-style and passed in junk so we fall back to
  		   comparing just the label */
  		if (!ifa) {

  			for (ifap = &in_dev->ifa_list;
  			     (ifa = rtnl_dereference(*ifap)) != NULL;

  			     ifap = &ifa->ifa_next)

  				if (!strcmp(ifr->ifr_name, ifa->ifa_label))

  					break;
  		}
  	}
  
  	ret = -EADDRNOTAVAIL;
  	if (!ifa && cmd != SIOCSIFADDR && cmd != SIOCSIFFLAGS)
  		goto done;

  	switch (cmd) {

  	case SIOCGIFADDR:	/* Get interface address */

  		ret = 0;

  		sin->sin_addr.s_addr = ifa->ifa_local;

  		break;

  
  	case SIOCGIFBRDADDR:	/* Get the broadcast address */

  		ret = 0;

  		sin->sin_addr.s_addr = ifa->ifa_broadcast;

  		break;

  
  	case SIOCGIFDSTADDR:	/* Get the destination address */

  		ret = 0;

  		sin->sin_addr.s_addr = ifa->ifa_address;

  		break;

  
  	case SIOCGIFNETMASK:	/* Get the netmask for the interface */

  		ret = 0;

  		sin->sin_addr.s_addr = ifa->ifa_mask;

  		break;

  
  	case SIOCSIFFLAGS:
  		if (colon) {
  			ret = -EADDRNOTAVAIL;
  			if (!ifa)
  				break;
  			ret = 0;

  			if (!(ifr->ifr_flags & IFF_UP))

  				inet_del_ifa(in_dev, ifap, 1);
  			break;
  		}

  		ret = dev_change_flags(dev, ifr->ifr_flags, NULL);

  		break;
  
  	case SIOCSIFADDR:	/* Set interface address (and family) */
  		ret = -EINVAL;
  		if (inet_abc_len(sin->sin_addr.s_addr) < 0)
  			break;
  
  		if (!ifa) {
  			ret = -ENOBUFS;

  			ifa = inet_alloc_ifa();
  			if (!ifa)

  				break;

  			INIT_HLIST_NODE(&ifa->hash);

  			if (colon)

  				memcpy(ifa->ifa_label, ifr->ifr_name, IFNAMSIZ);

  			else
  				memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);
  		} else {
  			ret = 0;
  			if (ifa->ifa_local == sin->sin_addr.s_addr)
  				break;
  			inet_del_ifa(in_dev, ifap, 0);
  			ifa->ifa_broadcast = 0;

  			ifa->ifa_scope = 0;

  		}
  
  		ifa->ifa_address = ifa->ifa_local = sin->sin_addr.s_addr;
  
  		if (!(dev->flags & IFF_POINTOPOINT)) {
  			ifa->ifa_prefixlen = inet_abc_len(ifa->ifa_address);
  			ifa->ifa_mask = inet_make_mask(ifa->ifa_prefixlen);
  			if ((dev->flags & IFF_BROADCAST) &&
  			    ifa->ifa_prefixlen < 31)
  				ifa->ifa_broadcast = ifa->ifa_address |
  						     ~ifa->ifa_mask;
  		} else {
  			ifa->ifa_prefixlen = 32;
  			ifa->ifa_mask = inet_make_mask(32);
  		}

  		set_ifa_lifetime(ifa, INFINITY_LIFE_TIME, INFINITY_LIFE_TIME);

  		ret = inet_set_ifa(dev, ifa);
  		break;
  
  	case SIOCSIFBRDADDR:	/* Set the broadcast address */
  		ret = 0;
  		if (ifa->ifa_broadcast != sin->sin_addr.s_addr) {
  			inet_del_ifa(in_dev, ifap, 0);
  			ifa->ifa_broadcast = sin->sin_addr.s_addr;
  			inet_insert_ifa(ifa);
  		}
  		break;
  
  	case SIOCSIFDSTADDR:	/* Set the destination address */
  		ret = 0;
  		if (ifa->ifa_address == sin->sin_addr.s_addr)
  			break;
  		ret = -EINVAL;
  		if (inet_abc_len(sin->sin_addr.s_addr) < 0)
  			break;
  		ret = 0;
  		inet_del_ifa(in_dev, ifap, 0);
  		ifa->ifa_address = sin->sin_addr.s_addr;
  		inet_insert_ifa(ifa);
  		break;
  
  	case SIOCSIFNETMASK: 	/* Set the netmask for the interface */
  
  		/*
  		 *	The mask we set must be legal.
  		 */
  		ret = -EINVAL;
  		if (bad_mask(sin->sin_addr.s_addr, 0))
  			break;
  		ret = 0;
  		if (ifa->ifa_mask != sin->sin_addr.s_addr) {

  			__be32 old_mask = ifa->ifa_mask;

  			inet_del_ifa(in_dev, ifap, 0);
  			ifa->ifa_mask = sin->sin_addr.s_addr;
  			ifa->ifa_prefixlen = inet_mask_len(ifa->ifa_mask);
  
  			/* See if current broadcast address matches
  			 * with current netmask, then recalculate
  			 * the broadcast address. Otherwise it's a
  			 * funny address, so don't touch it since
  			 * the user seems to know what (s)he's doing...
  			 */
  			if ((dev->flags & IFF_BROADCAST) &&
  			    (ifa->ifa_prefixlen < 31) &&
  			    (ifa->ifa_broadcast ==

  			     (ifa->ifa_local|~old_mask))) {

  				ifa->ifa_broadcast = (ifa->ifa_local |
  						      ~sin->sin_addr.s_addr);
  			}
  			inet_insert_ifa(ifa);
  		}
  		break;
  	}
  done:
  	rtnl_unlock();
  out:
  	return ret;

  }

  static int inet_gifconf(struct net_device *dev, char __user *buf, int len, int size)

  {

  	struct in_device *in_dev = __in_dev_get_rtnl(dev);

  	const struct in_ifaddr *ifa;

  	struct ifreq ifr;
  	int done = 0;

  	if (WARN_ON(size > sizeof(struct ifreq)))
  		goto out;

  	if (!in_dev)

  		goto out;

  	in_dev_for_each_ifa_rtnl(ifa, in_dev) {

  		if (!buf) {

  			done += size;

  			continue;
  		}

  		if (len < size)

  			break;
  		memset(&ifr, 0, sizeof(struct ifreq));

  		strcpy(ifr.ifr_name, ifa->ifa_label);

  
  		(*(struct sockaddr_in *)&ifr.ifr_addr).sin_family = AF_INET;
  		(*(struct sockaddr_in *)&ifr.ifr_addr).sin_addr.s_addr =
  								ifa->ifa_local;

  		if (copy_to_user(buf + done, &ifr, size)) {

  			done = -EFAULT;
  			break;
  		}

  		len  -= size;
  		done += size;

  	}
  out:
  	return done;
  }

  static __be32 in_dev_select_addr(const struct in_device *in_dev,
  				 int scope)
  {

  	const struct in_ifaddr *ifa;
  
  	in_dev_for_each_ifa_rcu(ifa, in_dev) {
  		if (ifa->ifa_flags & IFA_F_SECONDARY)
  			continue;

  		if (ifa->ifa_scope != RT_SCOPE_LINK &&
  		    ifa->ifa_scope <= scope)
  			return ifa->ifa_local;

  	}

  
  	return 0;
  }

  __be32 inet_select_addr(const struct net_device *dev, __be32 dst, int scope)

  {

  	const struct in_ifaddr *ifa;

  	__be32 addr = 0;

  	unsigned char localnet_scope = RT_SCOPE_HOST;

  	struct in_device *in_dev;

  	struct net *net = dev_net(dev);

  	int master_idx;

  
  	rcu_read_lock();

  	in_dev = __in_dev_get_rcu(dev);

  	if (!in_dev)
  		goto no_in_dev;

  	if (unlikely(IN_DEV_ROUTE_LOCALNET(in_dev)))
  		localnet_scope = RT_SCOPE_LINK;

  	in_dev_for_each_ifa_rcu(ifa, in_dev) {
  		if (ifa->ifa_flags & IFA_F_SECONDARY)
  			continue;

  		if (min(ifa->ifa_scope, localnet_scope) > scope)

  			continue;
  		if (!dst || inet_ifa_match(dst, ifa)) {
  			addr = ifa->ifa_local;
  			break;
  		}
  		if (!addr)
  			addr = ifa->ifa_local;

  	}

  
  	if (addr)

  		goto out_unlock;

  no_in_dev:

  	master_idx = l3mdev_master_ifindex_rcu(dev);

  	/* For VRFs, the VRF device takes the place of the loopback device,
  	 * with addresses on it being preferred.  Note in such cases the
  	 * loopback device will be among the devices that fail the master_idx
  	 * equality check in the loop below.
  	 */
  	if (master_idx &&
  	    (dev = dev_get_by_index_rcu(net, master_idx)) &&
  	    (in_dev = __in_dev_get_rcu(dev))) {

  		addr = in_dev_select_addr(in_dev, scope);
  		if (addr)
  			goto out_unlock;

  	}

  	/* Not loopback addresses on loopback should be preferred

  	   in this case. It is important that lo is the first interface

  	   in dev_base list.
  	 */

  	for_each_netdev_rcu(net, dev) {

  		if (l3mdev_master_ifindex_rcu(dev) != master_idx)
  			continue;

  		in_dev = __in_dev_get_rcu(dev);
  		if (!in_dev)

  			continue;

  		addr = in_dev_select_addr(in_dev, scope);
  		if (addr)
  			goto out_unlock;

  	}

  out_unlock:

  	rcu_read_unlock();

  	return addr;
  }

  EXPORT_SYMBOL(inet_select_addr);

  static __be32 confirm_addr_indev(struct in_device *in_dev, __be32 dst,
  			      __be32 local, int scope)

  {

  	unsigned char localnet_scope = RT_SCOPE_HOST;

  	const struct in_ifaddr *ifa;

  	__be32 addr = 0;

  	int same = 0;

  	if (unlikely(IN_DEV_ROUTE_LOCALNET(in_dev)))
  		localnet_scope = RT_SCOPE_LINK;

  	in_dev_for_each_ifa_rcu(ifa, in_dev) {

  		unsigned char min_scope = min(ifa->ifa_scope, localnet_scope);

  		if (!addr &&
  		    (local == ifa->ifa_local || !local) &&

  		    min_scope <= scope) {

  			addr = ifa->ifa_local;
  			if (same)
  				break;
  		}
  		if (!same) {
  			same = (!local || inet_ifa_match(local, ifa)) &&
  				(!dst || inet_ifa_match(dst, ifa));
  			if (same && addr) {
  				if (local || !dst)
  					break;
  				/* Is the selected addr into dst subnet? */
  				if (inet_ifa_match(addr, ifa))
  					break;
  				/* No, then can we use new local src? */

  				if (min_scope <= scope) {

  					addr = ifa->ifa_local;
  					break;
  				}
  				/* search for large dst subnet for addr */
  				same = 0;
  			}
  		}

  	}

  	return same ? addr : 0;

  }
  
  /*
   * Confirm that local IP address exists using wildcards:

   * - net: netns to check, cannot be NULL
   * - in_dev: only on this interface, NULL=any interface

   * - dst: only in the same subnet as dst, 0=any dst
   * - local: address, 0=autoselect the local address
   * - scope: maximum allowed scope value for the local address
   */

  __be32 inet_confirm_addr(struct net *net, struct in_device *in_dev,

  			 __be32 dst, __be32 local, int scope)

  {

  	__be32 addr = 0;

  	struct net_device *dev;

  	if (in_dev)

  		return confirm_addr_indev(in_dev, dst, local, scope);

  	rcu_read_lock();

  	for_each_netdev_rcu(net, dev) {

  		in_dev = __in_dev_get_rcu(dev);
  		if (in_dev) {

  			addr = confirm_addr_indev(in_dev, dst, local, scope);
  			if (addr)
  				break;
  		}
  	}
  	rcu_read_unlock();

  
  	return addr;
  }

  EXPORT_SYMBOL(inet_confirm_addr);

  
  /*
   *	Device notifier
   */
  
  int register_inetaddr_notifier(struct notifier_block *nb)
  {

  	return blocking_notifier_chain_register(&inetaddr_chain, nb);

  }

  EXPORT_SYMBOL(register_inetaddr_notifier);

  
  int unregister_inetaddr_notifier(struct notifier_block *nb)
  {

  	return blocking_notifier_chain_unregister(&inetaddr_chain, nb);

  }

  EXPORT_SYMBOL(unregister_inetaddr_notifier);

  int register_inetaddr_validator_notifier(struct notifier_block *nb)
  {
  	return blocking_notifier_chain_register(&inetaddr_validator_chain, nb);
  }
  EXPORT_SYMBOL(register_inetaddr_validator_notifier);
  
  int unregister_inetaddr_validator_notifier(struct notifier_block *nb)
  {
  	return blocking_notifier_chain_unregister(&inetaddr_validator_chain,
  	    nb);
  }
  EXPORT_SYMBOL(unregister_inetaddr_validator_notifier);

  /* Rename ifa_labels for a device name change. Make some effort to preserve
   * existing alias numbering and to create unique labels if possible.

  */
  static void inetdev_changename(struct net_device *dev, struct in_device *in_dev)

  {

  	struct in_ifaddr *ifa;
  	int named = 0;

  	in_dev_for_each_ifa_rtnl(ifa, in_dev) {

  		char old[IFNAMSIZ], *dot;

  
  		memcpy(old, ifa->ifa_label, IFNAMSIZ);

  		memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);

  		if (named++ == 0)

  			goto skip;

  		dot = strchr(old, ':');

  		if (!dot) {

  			sprintf(old, ":%d", named);

  			dot = old;
  		}

  		if (strlen(dot) + strlen(dev->name) < IFNAMSIZ)

  			strcat(ifa->ifa_label, dot);

  		else

  			strcpy(ifa->ifa_label + (IFNAMSIZ - strlen(dot) - 1), dot);

  skip:
  		rtmsg_ifa(RTM_NEWADDR, ifa, NULL, 0);

  	}
  }

  static void inetdev_send_gratuitous_arp(struct net_device *dev,
  					struct in_device *in_dev)
  
  {

  	const struct in_ifaddr *ifa;

  	in_dev_for_each_ifa_rtnl(ifa, in_dev) {

  		arp_send(ARPOP_REQUEST, ETH_P_ARP,
  			 ifa->ifa_local, dev,
  			 ifa->ifa_local, NULL,
  			 dev->dev_addr, NULL);
  	}

  }

  /* Called only under RTNL semaphore */
  
  static int inetdev_event(struct notifier_block *this, unsigned long event,
  			 void *ptr)
  {

  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);

  	struct in_device *in_dev = __in_dev_get_rtnl(dev);

  	ASSERT_RTNL();
  
  	if (!in_dev) {

  		if (event == NETDEV_REGISTER) {

  			in_dev = inetdev_init(dev);

  			if (IS_ERR(in_dev))
  				return notifier_from_errno(PTR_ERR(in_dev));

  			if (dev->flags & IFF_LOOPBACK) {

  				IN_DEV_CONF_SET(in_dev, NOXFRM, 1);
  				IN_DEV_CONF_SET(in_dev, NOPOLICY, 1);

  			}

  		} else if (event == NETDEV_CHANGEMTU) {
  			/* Re-enabling IP */
  			if (inetdev_valid_mtu(dev->mtu))
  				in_dev = inetdev_init(dev);

  		}
  		goto out;
  	}
  
  	switch (event) {
  	case NETDEV_REGISTER:

  		pr_debug("%s: bug
  ", __func__);

  		RCU_INIT_POINTER(dev->ip_ptr, NULL);

  		break;
  	case NETDEV_UP:

  		if (!inetdev_valid_mtu(dev->mtu))

  			break;

  		if (dev->flags & IFF_LOOPBACK) {