xref: /linux/net/core/neighbour.c (revision 0542972950ef26670a5696e43c0ea2b7b6ac96d4)

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	Generic address resolution entity
 *
 *	Authors:
 *	Pedro Roque		<roque@di.fc.ul.pt>
 *	Alexey Kuznetsov	<kuznet@ms2.inr.ac.ru>
 *
 *	Fixes:
 *	Vitaly E. Lavrov	releasing NULL neighbor in neigh_add.
 *	Harald Welte		Add neighbour cache statistics like rtstat
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/socket.h>
#include <linux/netdevice.h>
#include <linux/proc_fs.h>
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif
#include <linux/times.h>
#include <net/net_namespace.h>
#include <net/neighbour.h>
#include <net/arp.h>
#include <net/dst.h>
#include <net/ip.h>
#include <net/sock.h>
#include <net/netevent.h>
#include <net/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/random.h>
#include <linux/string.h>
#include <linux/log2.h>
#include <linux/inetdevice.h>
#include <net/addrconf.h>

#include <trace/events/neigh.h>

#define NEIGH_DEBUG 1
#define neigh_dbg(level, fmt, ...)		\
do {						\
	if (level <= NEIGH_DEBUG)		\
		pr_debug(fmt, ##__VA_ARGS__);	\
} while (0)

#define PNEIGH_HASHMASK		0xF

static void neigh_timer_handler(struct timer_list *t);
static void neigh_notify(struct neighbour *n, int type, int flags, u32 pid);
static void __neigh_notify(struct neighbour *n, int type, int flags, u32 pid);
static void pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev,
			  bool skip_perm);

#ifdef CONFIG_PROC_FS
static const struct seq_operations neigh_stat_seq_ops;
#endif

static struct hlist_head *neigh_get_dev_table(struct net_device *dev, int family)
{
	int i;

	switch (family) {
	default:
		DEBUG_NET_WARN_ON_ONCE(1);
		fallthrough; /* to avoid panic by null-ptr-deref */
	case AF_INET:
		i = NEIGH_ARP_TABLE;
		break;
	case AF_INET6:
		i = NEIGH_ND_TABLE;
		break;
	}

	return &dev->neighbours[i];
}

/*
   Neighbour hash table buckets are protected with tbl->lock.

   - All the scans/updates to hash buckets MUST be made under this lock.
   - NOTHING clever should be made under this lock: no callbacks
     to protocol backends, no attempts to send something to network.
     It will result in deadlocks, if backend/driver wants to use neighbour
     cache.
   - If the entry requires some non-trivial actions, increase
     its reference count and release table lock.

   Neighbour entries are protected:
   - with reference count.
   - with rwlock neigh->lock

   Reference count prevents destruction.

   neigh->lock mainly serializes ll address data and its validity state.
   However, the same lock is used to protect another entry fields:
    - timer
    - resolution queue

   Again, nothing clever shall be made under neigh->lock,
   the most complicated procedure, which we allow is dev->hard_header.
   It is supposed, that dev->hard_header is simplistic and does
   not make callbacks to neighbour tables.
 */

static int neigh_blackhole(struct neighbour *neigh, struct sk_buff *skb)
{
	kfree_skb(skb);
	return -ENETDOWN;
}

static void neigh_cleanup_and_release(struct neighbour *neigh)
{
	trace_neigh_cleanup_and_release(neigh, 0);
	neigh_notify(neigh, RTM_DELNEIGH, 0, 0);
	call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);
	neigh_release(neigh);
}

/*
 * It is random distribution in the interval (1/2)*base...(3/2)*base.
 * It corresponds to default IPv6 settings and is not overridable,
 * because it is really reasonable choice.
 */

unsigned long neigh_rand_reach_time(unsigned long base)
{
	return base ? get_random_u32_below(base) + (base >> 1) : 0;
}
EXPORT_SYMBOL(neigh_rand_reach_time);

static void neigh_mark_dead(struct neighbour *n)
{
	n->dead = 1;
	if (!list_empty(&n->gc_list)) {
		list_del_init(&n->gc_list);
		atomic_dec(&n->tbl->gc_entries);
	}
	if (!list_empty(&n->managed_list))
		list_del_init(&n->managed_list);
}

static void neigh_update_gc_list(struct neighbour *n)
{
	bool on_gc_list, exempt_from_gc;

	spin_lock_bh(&n->tbl->lock);
	write_lock(&n->lock);
	if (n->dead)
		goto out;

	/* remove from the gc list if new state is permanent or if neighbor is
	 * externally learned / validated; otherwise entry should be on the gc
	 * list
	 */
	exempt_from_gc = n->nud_state & NUD_PERMANENT ||
			 n->flags & (NTF_EXT_LEARNED | NTF_EXT_VALIDATED);
	on_gc_list = !list_empty(&n->gc_list);

	if (exempt_from_gc && on_gc_list) {
		list_del_init(&n->gc_list);
		atomic_dec(&n->tbl->gc_entries);
	} else if (!exempt_from_gc && !on_gc_list) {
		/* add entries to the tail; cleaning removes from the front */
		list_add_tail(&n->gc_list, &n->tbl->gc_list);
		atomic_inc(&n->tbl->gc_entries);
	}
out:
	write_unlock(&n->lock);
	spin_unlock_bh(&n->tbl->lock);
}

static void neigh_update_managed_list(struct neighbour *n)
{
	bool on_managed_list, add_to_managed;

	spin_lock_bh(&n->tbl->lock);
	write_lock(&n->lock);
	if (n->dead)
		goto out;

	add_to_managed = n->flags & NTF_MANAGED;
	on_managed_list = !list_empty(&n->managed_list);

	if (!add_to_managed && on_managed_list)
		list_del_init(&n->managed_list);
	else if (add_to_managed && !on_managed_list)
		list_add_tail(&n->managed_list, &n->tbl->managed_list);
out:
	write_unlock(&n->lock);
	spin_unlock_bh(&n->tbl->lock);
}

static void neigh_update_flags(struct neighbour *neigh, u32 flags, int *notify,
			       bool *gc_update, bool *managed_update)
{
	u32 ndm_flags, old_flags = neigh->flags;

	if (!(flags & NEIGH_UPDATE_F_ADMIN))
		return;

	ndm_flags  = (flags & NEIGH_UPDATE_F_EXT_LEARNED) ? NTF_EXT_LEARNED : 0;
	ndm_flags |= (flags & NEIGH_UPDATE_F_MANAGED) ? NTF_MANAGED : 0;
	ndm_flags |= (flags & NEIGH_UPDATE_F_EXT_VALIDATED) ? NTF_EXT_VALIDATED : 0;

	if ((old_flags ^ ndm_flags) & NTF_EXT_LEARNED) {
		if (ndm_flags & NTF_EXT_LEARNED)
			neigh->flags |= NTF_EXT_LEARNED;
		else
			neigh->flags &= ~NTF_EXT_LEARNED;
		*notify = 1;
		*gc_update = true;
	}
	if ((old_flags ^ ndm_flags) & NTF_MANAGED) {
		if (ndm_flags & NTF_MANAGED)
			neigh->flags |= NTF_MANAGED;
		else
			neigh->flags &= ~NTF_MANAGED;
		*notify = 1;
		*managed_update = true;
	}
	if ((old_flags ^ ndm_flags) & NTF_EXT_VALIDATED) {
		if (ndm_flags & NTF_EXT_VALIDATED)
			neigh->flags |= NTF_EXT_VALIDATED;
		else
			neigh->flags &= ~NTF_EXT_VALIDATED;
		*notify = 1;
		*gc_update = true;
	}
}

bool neigh_remove_one(struct neighbour *n)
{
	bool retval = false;

	write_lock(&n->lock);
	if (refcount_read(&n->refcnt) == 1) {
		hlist_del_rcu(&n->hash);
		hlist_del_rcu(&n->dev_list);
		neigh_mark_dead(n);
		retval = true;
	}
	write_unlock(&n->lock);
	if (retval)
		neigh_cleanup_and_release(n);
	return retval;
}

static int neigh_forced_gc(struct neigh_table *tbl)
{
	int max_clean = atomic_read(&tbl->gc_entries) -
			READ_ONCE(tbl->gc_thresh2);
	u64 tmax = ktime_get_ns() + NSEC_PER_MSEC;
	unsigned long tref = jiffies - 5 * HZ;
	struct neighbour *n, *tmp;
	int shrunk = 0;
	int loop = 0;

	NEIGH_CACHE_STAT_INC(tbl, forced_gc_runs);

	spin_lock_bh(&tbl->lock);

	list_for_each_entry_safe(n, tmp, &tbl->gc_list, gc_list) {
		if (refcount_read(&n->refcnt) == 1) {
			bool remove = false;

			write_lock(&n->lock);
			if ((n->nud_state == NUD_FAILED) ||
			    (n->nud_state == NUD_NOARP) ||
			    (tbl->is_multicast &&
			     tbl->is_multicast(n->primary_key)) ||
			    !time_in_range(n->updated, tref, jiffies))
				remove = true;
			write_unlock(&n->lock);

			if (remove && neigh_remove_one(n))
				shrunk++;
			if (shrunk >= max_clean)
				break;
			if (++loop == 16) {
				if (ktime_get_ns() > tmax)
					goto unlock;
				loop = 0;
			}
		}
	}

	WRITE_ONCE(tbl->last_flush, jiffies);
unlock:
	spin_unlock_bh(&tbl->lock);

	return shrunk;
}

static void neigh_add_timer(struct neighbour *n, unsigned long when)
{
	/* Use safe distance from the jiffies - LONG_MAX point while timer
	 * is running in DELAY/PROBE state but still show to user space
	 * large times in the past.
	 */
	unsigned long mint = jiffies - (LONG_MAX - 86400 * HZ);

	neigh_hold(n);
	if (!time_in_range(n->confirmed, mint, jiffies))
		n->confirmed = mint;
	if (time_before(n->used, n->confirmed))
		n->used = n->confirmed;
	if (unlikely(mod_timer(&n->timer, when))) {
		printk("NEIGH: BUG, double timer add, state is %x\n",
		       n->nud_state);
		dump_stack();
	}
}

static int neigh_del_timer(struct neighbour *n)
{
	if ((n->nud_state & NUD_IN_TIMER) &&
	    timer_delete(&n->timer)) {
		neigh_release(n);
		return 1;
	}
	return 0;
}

static struct neigh_parms *neigh_get_dev_parms_rcu(struct net_device *dev,
						   int family)
{
	switch (family) {
	case AF_INET:
		return __in_dev_arp_parms_get_rcu(dev);
	case AF_INET6:
		return __in6_dev_nd_parms_get_rcu(dev);
	}
	return NULL;
}

static void neigh_parms_qlen_dec(struct net_device *dev, int family)
{
	struct neigh_parms *p;

	rcu_read_lock();
	p = neigh_get_dev_parms_rcu(dev, family);
	if (p)
		p->qlen--;
	rcu_read_unlock();
}

static void pneigh_queue_purge(struct sk_buff_head *list, struct net *net,
			       int family)
{
	struct sk_buff_head tmp;
	unsigned long flags;
	struct sk_buff *skb;

	skb_queue_head_init(&tmp);
	spin_lock_irqsave(&list->lock, flags);
	skb = skb_peek(list);
	while (skb != NULL) {
		struct sk_buff *skb_next = skb_peek_next(skb, list);
		struct net_device *dev = skb->dev;

		if (net == NULL || net_eq(dev_net(dev), net)) {
			neigh_parms_qlen_dec(dev, family);
			__skb_unlink(skb, list);
			__skb_queue_tail(&tmp, skb);
		}
		skb = skb_next;
	}
	spin_unlock_irqrestore(&list->lock, flags);

	while ((skb = __skb_dequeue(&tmp))) {
		dev_put(skb->dev);
		kfree_skb(skb);
	}
}

static void neigh_flush_one(struct neighbour *n)
{
	hlist_del_rcu(&n->hash);
	hlist_del_rcu(&n->dev_list);

	write_lock(&n->lock);

	neigh_del_timer(n);
	neigh_mark_dead(n);

	if (refcount_read(&n->refcnt) != 1) {
		/* The most unpleasant situation.
		 * We must destroy neighbour entry,
		 * but someone still uses it.
		 *
		 * The destroy will be delayed until
		 * the last user releases us, but
		 * we must kill timers etc. and move
		 * it to safe state.
		 */
		__skb_queue_purge(&n->arp_queue);
		n->arp_queue_len_bytes = 0;
		WRITE_ONCE(n->output, neigh_blackhole);

		if (n->nud_state & NUD_VALID)
			n->nud_state = NUD_NOARP;
		else
			n->nud_state = NUD_NONE;

		neigh_dbg(2, "neigh %p is stray\n", n);
	}

	write_unlock(&n->lock);

	neigh_cleanup_and_release(n);
}

static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev,
			    bool skip_perm)
{
	struct hlist_head *dev_head;
	struct hlist_node *tmp;
	struct neighbour *n;

	dev_head = neigh_get_dev_table(dev, tbl->family);

	hlist_for_each_entry_safe(n, tmp, dev_head, dev_list) {
		if (skip_perm &&
		    (n->nud_state & NUD_PERMANENT ||
		     n->flags & NTF_EXT_VALIDATED))
			continue;

		neigh_flush_one(n);
	}
}

static void neigh_flush_table(struct neigh_table *tbl)
{
	struct neigh_hash_table *nht;
	int i;

	nht = rcu_dereference_protected(tbl->nht,
					lockdep_is_held(&tbl->lock));

	for (i = 0; i < (1 << nht->hash_shift); i++) {
		struct hlist_node *tmp;
		struct neighbour *n;

		neigh_for_each_in_bucket_safe(n, tmp, &nht->hash_heads[i])
			neigh_flush_one(n);
	}
}

void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev)
{
	spin_lock_bh(&tbl->lock);
	neigh_flush_dev(tbl, dev, false);
	spin_unlock_bh(&tbl->lock);
}
EXPORT_SYMBOL(neigh_changeaddr);

static int __neigh_ifdown(struct neigh_table *tbl, struct net_device *dev,
			  bool skip_perm)
{
	spin_lock_bh(&tbl->lock);
	if (likely(dev)) {
		neigh_flush_dev(tbl, dev, skip_perm);
	} else {
		DEBUG_NET_WARN_ON_ONCE(skip_perm);
		neigh_flush_table(tbl);
	}
	spin_unlock_bh(&tbl->lock);

	pneigh_ifdown(tbl, dev, skip_perm);
	pneigh_queue_purge(&tbl->proxy_queue, dev ? dev_net(dev) : NULL,
			   tbl->family);
	if (skb_queue_empty_lockless(&tbl->proxy_queue))
		timer_delete_sync(&tbl->proxy_timer);
	return 0;
}

int neigh_carrier_down(struct neigh_table *tbl, struct net_device *dev)
{
	__neigh_ifdown(tbl, dev, true);
	return 0;
}
EXPORT_SYMBOL(neigh_carrier_down);

int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
{
	__neigh_ifdown(tbl, dev, false);
	return 0;
}
EXPORT_SYMBOL(neigh_ifdown);

static struct neighbour *neigh_alloc(struct neigh_table *tbl,
				     struct net_device *dev,
				     u32 flags, bool exempt_from_gc)
{
	struct neighbour *n = NULL;
	unsigned long now = jiffies;
	int entries, gc_thresh3;

	if (exempt_from_gc)
		goto do_alloc;

	entries = atomic_inc_return(&tbl->gc_entries) - 1;
	gc_thresh3 = READ_ONCE(tbl->gc_thresh3);
	if (entries >= gc_thresh3 ||
	    (entries >= READ_ONCE(tbl->gc_thresh2) &&
	     time_after(now, READ_ONCE(tbl->last_flush) + 5 * HZ))) {
		if (!neigh_forced_gc(tbl) && entries >= gc_thresh3) {
			net_info_ratelimited("%s: neighbor table overflow!\n",
					     tbl->id);
			NEIGH_CACHE_STAT_INC(tbl, table_fulls);
			goto out_entries;
		}
	}

do_alloc:
	n = kzalloc(tbl->entry_size + dev->neigh_priv_len, GFP_ATOMIC);
	if (!n)
		goto out_entries;

	__skb_queue_head_init(&n->arp_queue);
	rwlock_init(&n->lock);
	seqlock_init(&n->ha_lock);
	n->updated	  = n->used = now;
	n->nud_state	  = NUD_NONE;
	n->output	  = neigh_blackhole;
	n->flags	  = flags;
	seqlock_init(&n->hh.hh_lock);
	n->parms	  = neigh_parms_clone(&tbl->parms);
	timer_setup(&n->timer, neigh_timer_handler, 0);

	NEIGH_CACHE_STAT_INC(tbl, allocs);
	n->tbl		  = tbl;
	refcount_set(&n->refcnt, 1);
	n->dead		  = 1;
	INIT_LIST_HEAD(&n->gc_list);
	INIT_LIST_HEAD(&n->managed_list);

	atomic_inc(&tbl->entries);
out:
	return n;

out_entries:
	if (!exempt_from_gc)
		atomic_dec(&tbl->gc_entries);
	goto out;
}

static void neigh_get_hash_rnd(u32 *x)
{
	*x = get_random_u32() | 1;
}

static struct neigh_hash_table *neigh_hash_alloc(unsigned int shift)
{
	size_t size = (1 << shift) * sizeof(struct hlist_head);
	struct hlist_head *hash_heads;
	struct neigh_hash_table *ret;
	int i;

	ret = kmalloc_obj(*ret, GFP_ATOMIC);
	if (!ret)
		return NULL;

	hash_heads = kzalloc(size, GFP_ATOMIC);
	if (!hash_heads) {
		kfree(ret);
		return NULL;
	}
	ret->hash_heads = hash_heads;
	ret->hash_shift = shift;
	for (i = 0; i < NEIGH_NUM_HASH_RND; i++)
		neigh_get_hash_rnd(&ret->hash_rnd[i]);
	return ret;
}

static void neigh_hash_free_rcu(struct rcu_head *head)
{
	struct neigh_hash_table *nht = container_of(head,
						    struct neigh_hash_table,
						    rcu);

	kfree(nht->hash_heads);
	kfree(nht);
}

static struct neigh_hash_table *neigh_hash_grow(struct neigh_table *tbl,
						unsigned long new_shift)
{
	unsigned int i, hash;
	struct neigh_hash_table *new_nht, *old_nht;

	NEIGH_CACHE_STAT_INC(tbl, hash_grows);

	old_nht = rcu_dereference_protected(tbl->nht,
					    lockdep_is_held(&tbl->lock));
	new_nht = neigh_hash_alloc(new_shift);
	if (!new_nht)
		return old_nht;

	for (i = 0; i < (1 << old_nht->hash_shift); i++) {
		struct hlist_node *tmp;
		struct neighbour *n;

		neigh_for_each_in_bucket_safe(n, tmp, &old_nht->hash_heads[i]) {
			hash = tbl->hash(n->primary_key, n->dev,
					 new_nht->hash_rnd);

			hash >>= (32 - new_nht->hash_shift);

			hlist_del_rcu(&n->hash);
			hlist_add_head_rcu(&n->hash, &new_nht->hash_heads[hash]);
		}
	}

	rcu_assign_pointer(tbl->nht, new_nht);
	call_rcu(&old_nht->rcu, neigh_hash_free_rcu);
	return new_nht;
}

struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
			       struct net_device *dev)
{
	struct neighbour *n;

	NEIGH_CACHE_STAT_INC(tbl, lookups);

	rcu_read_lock();
	n = __neigh_lookup_noref(tbl, pkey, dev);
	if (n) {
		if (!refcount_inc_not_zero(&n->refcnt))
			n = NULL;
		NEIGH_CACHE_STAT_INC(tbl, hits);
	}

	rcu_read_unlock();
	return n;
}
EXPORT_SYMBOL(neigh_lookup);

static struct neighbour *
___neigh_create(struct neigh_table *tbl, const void *pkey,
		struct net_device *dev, u32 flags,
		bool exempt_from_gc, bool want_ref)
{
	u32 hash_val, key_len = tbl->key_len;
	struct neighbour *n1, *rc, *n;
	struct neigh_hash_table *nht;
	int error;

	n = neigh_alloc(tbl, dev, flags, exempt_from_gc);
	trace_neigh_create(tbl, dev, pkey, n, exempt_from_gc);
	if (!n) {
		rc = ERR_PTR(-ENOBUFS);
		goto out;
	}

	memcpy(n->primary_key, pkey, key_len);
	n->dev = dev;
	netdev_hold(dev, &n->dev_tracker, GFP_ATOMIC);

	/* Protocol specific setup. */
	if (tbl->constructor &&	(error = tbl->constructor(n)) < 0) {
		rc = ERR_PTR(error);
		goto out_neigh_release;
	}

	if (dev->netdev_ops->ndo_neigh_construct) {
		error = dev->netdev_ops->ndo_neigh_construct(dev, n);
		if (error < 0) {
			rc = ERR_PTR(error);
			goto out_neigh_release;
		}
	}

	/* Device specific setup. */
	if (n->parms->neigh_setup &&
	    (error = n->parms->neigh_setup(n)) < 0) {
		rc = ERR_PTR(error);
		goto out_neigh_release;
	}

	n->confirmed = jiffies - (NEIGH_VAR(n->parms, BASE_REACHABLE_TIME) << 1);

	spin_lock_bh(&tbl->lock);
	nht = rcu_dereference_protected(tbl->nht,
					lockdep_is_held(&tbl->lock));

	if (atomic_read(&tbl->entries) > (1 << nht->hash_shift))
		nht = neigh_hash_grow(tbl, nht->hash_shift + 1);

	hash_val = tbl->hash(n->primary_key, dev, nht->hash_rnd) >> (32 - nht->hash_shift);

	if (n->parms->dead) {
		rc = ERR_PTR(-EINVAL);
		goto out_tbl_unlock;
	}

	neigh_for_each_in_bucket(n1, &nht->hash_heads[hash_val]) {
		if (dev == n1->dev && !memcmp(n1->primary_key, n->primary_key, key_len)) {
			if (want_ref)
				neigh_hold(n1);
			rc = n1;
			goto out_tbl_unlock;
		}
	}

	n->dead = 0;
	if (!exempt_from_gc)
		list_add_tail(&n->gc_list, &n->tbl->gc_list);
	if (n->flags & NTF_MANAGED)
		list_add_tail(&n->managed_list, &n->tbl->managed_list);
	if (want_ref)
		neigh_hold(n);
	hlist_add_head_rcu(&n->hash, &nht->hash_heads[hash_val]);

	hlist_add_head_rcu(&n->dev_list,
			   neigh_get_dev_table(dev, tbl->family));

	spin_unlock_bh(&tbl->lock);
	neigh_dbg(2, "neigh %p is created\n", n);
	rc = n;
out:
	return rc;
out_tbl_unlock:
	spin_unlock_bh(&tbl->lock);
out_neigh_release:
	if (!exempt_from_gc)
		atomic_dec(&tbl->gc_entries);
	neigh_release(n);
	goto out;
}

struct neighbour *__neigh_create(struct neigh_table *tbl, const void *pkey,
				 struct net_device *dev, bool want_ref)
{
	bool exempt_from_gc = !!(dev->flags & IFF_LOOPBACK);

	return ___neigh_create(tbl, pkey, dev, 0, exempt_from_gc, want_ref);
}
EXPORT_SYMBOL(__neigh_create);

static u32 pneigh_hash(const void *pkey, unsigned int key_len)
{
	u32 hash_val = *(u32 *)(pkey + key_len - 4);
	hash_val ^= (hash_val >> 16);
	hash_val ^= hash_val >> 8;
	hash_val ^= hash_val >> 4;
	hash_val &= PNEIGH_HASHMASK;
	return hash_val;
}

struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl,
				   struct net *net, const void *pkey,
				   struct net_device *dev)
{
	struct pneigh_entry *n;
	unsigned int key_len;
	u32 hash_val;

	key_len = tbl->key_len;
	hash_val = pneigh_hash(pkey, key_len);
	n = rcu_dereference_check(tbl->phash_buckets[hash_val],
				  lockdep_is_held(&tbl->phash_lock));

	while (n) {
		if (!memcmp(n->key, pkey, key_len) &&
		    net_eq(pneigh_net(n), net) &&
		    (n->dev == dev || !n->dev))
			return n;

		n = rcu_dereference_check(n->next, lockdep_is_held(&tbl->phash_lock));
	}

	return NULL;
}
EXPORT_IPV6_MOD(pneigh_lookup);

int pneigh_create(struct neigh_table *tbl, struct net *net,
		  const void *pkey, struct net_device *dev,
		  u32 flags, u8 protocol, bool permanent)
{
	struct pneigh_entry *n;
	unsigned int key_len;
	u32 hash_val;
	int err = 0;

	mutex_lock(&tbl->phash_lock);

	n = pneigh_lookup(tbl, net, pkey, dev);
	if (n)
		goto update;

	key_len = tbl->key_len;
	n = kzalloc(sizeof(*n) + key_len, GFP_KERNEL);
	if (!n) {
		err = -ENOBUFS;
		goto out;
	}

	write_pnet(&n->net, net);
	memcpy(n->key, pkey, key_len);
	n->dev = dev;
	netdev_hold(dev, &n->dev_tracker, GFP_KERNEL);

	if (tbl->pconstructor && tbl->pconstructor(n)) {
		netdev_put(dev, &n->dev_tracker);
		kfree(n);
		err = -ENOBUFS;
		goto out;
	}

	hash_val = pneigh_hash(pkey, key_len);
	n->next = tbl->phash_buckets[hash_val];
	rcu_assign_pointer(tbl->phash_buckets[hash_val], n);
update:
	WRITE_ONCE(n->flags, flags);
	n->permanent = permanent;
	if (protocol)
		WRITE_ONCE(n->protocol, protocol);
out:
	mutex_unlock(&tbl->phash_lock);
	return err;
}

static void pneigh_destroy(struct rcu_head *rcu)
{
	struct pneigh_entry *n = container_of(rcu, struct pneigh_entry, rcu);

	netdev_put(n->dev, &n->dev_tracker);
	kfree(n);
}

int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *pkey,
		  struct net_device *dev)
{
	struct pneigh_entry *n, __rcu **np;
	unsigned int key_len;
	u32 hash_val;

	key_len = tbl->key_len;
	hash_val = pneigh_hash(pkey, key_len);

	mutex_lock(&tbl->phash_lock);

	for (np = &tbl->phash_buckets[hash_val];
	     (n = rcu_dereference_protected(*np, 1)) != NULL;
	     np = &n->next) {
		if (!memcmp(n->key, pkey, key_len) && n->dev == dev &&
		    net_eq(pneigh_net(n), net)) {
			rcu_assign_pointer(*np, n->next);

			mutex_unlock(&tbl->phash_lock);

			if (tbl->pdestructor)
				tbl->pdestructor(n);

			call_rcu(&n->rcu, pneigh_destroy);
			return 0;
		}
	}

	mutex_unlock(&tbl->phash_lock);
	return -ENOENT;
}

static void pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev,
			  bool skip_perm)
{
	struct pneigh_entry *n, __rcu **np;
	LIST_HEAD(head);
	u32 h;

	mutex_lock(&tbl->phash_lock);

	for (h = 0; h <= PNEIGH_HASHMASK; h++) {
		np = &tbl->phash_buckets[h];
		while ((n = rcu_dereference_protected(*np, 1)) != NULL) {
			if (skip_perm && n->permanent)
				goto skip;
			if (!dev || n->dev == dev) {
				rcu_assign_pointer(*np, n->next);
				list_add(&n->free_node, &head);
				continue;
			}
skip:
			np = &n->next;
		}
	}

	mutex_unlock(&tbl->phash_lock);

	while (!list_empty(&head)) {
		n = list_first_entry(&head, typeof(*n), free_node);
		list_del(&n->free_node);

		if (tbl->pdestructor)
			tbl->pdestructor(n);

		call_rcu(&n->rcu, pneigh_destroy);
	}
}

static inline void neigh_parms_put(struct neigh_parms *parms)
{
	if (refcount_dec_and_test(&parms->refcnt))
		kfree(parms);
}

/*
 *	neighbour must already be out of the table;
 *
 */
void neigh_destroy(struct neighbour *neigh)
{
	struct net_device *dev = neigh->dev;

	NEIGH_CACHE_STAT_INC(neigh->tbl, destroys);

	if (!neigh->dead) {
		pr_warn("Destroying alive neighbour %p\n", neigh);
		dump_stack();
		return;
	}

	if (neigh_del_timer(neigh))
		pr_warn("Impossible event\n");

	write_lock_bh(&neigh->lock);
	__skb_queue_purge(&neigh->arp_queue);
	write_unlock_bh(&neigh->lock);
	neigh->arp_queue_len_bytes = 0;

	if (dev->netdev_ops->ndo_neigh_destroy)
		dev->netdev_ops->ndo_neigh_destroy(dev, neigh);

	netdev_put(dev, &neigh->dev_tracker);
	neigh_parms_put(neigh->parms);

	neigh_dbg(2, "neigh %p is destroyed\n", neigh);

	atomic_dec(&neigh->tbl->entries);
	kfree_rcu(neigh, rcu);
}
EXPORT_SYMBOL(neigh_destroy);

/* Neighbour state is suspicious;
   disable fast path.

   Called with write_locked neigh.
 */
static void neigh_suspect(struct neighbour *neigh)
{
	neigh_dbg(2, "neigh %p is suspected\n", neigh);

	WRITE_ONCE(neigh->output, neigh->ops->output);
}

/* Neighbour state is OK;
   enable fast path.

   Called with write_locked neigh.
 */
static void neigh_connect(struct neighbour *neigh)
{
	neigh_dbg(2, "neigh %p is connected\n", neigh);

	WRITE_ONCE(neigh->output, neigh->ops->connected_output);
}

static void neigh_periodic_work(struct work_struct *work)
{
	struct neigh_table *tbl = container_of(work, struct neigh_table, gc_work.work);
	struct neigh_hash_table *nht;
	struct hlist_node *tmp;
	struct neighbour *n;
	unsigned int i;

	NEIGH_CACHE_STAT_INC(tbl, periodic_gc_runs);

	spin_lock_bh(&tbl->lock);
	nht = rcu_dereference_protected(tbl->nht,
					lockdep_is_held(&tbl->lock));

	/*
	 *	periodically recompute ReachableTime from random function
	 */

	if (time_after(jiffies, tbl->last_rand + 300 * HZ)) {
		struct neigh_parms *p;

		WRITE_ONCE(tbl->last_rand, jiffies);
		list_for_each_entry(p, &tbl->parms_list, list)
			neigh_set_reach_time(p);
	}

	if (atomic_read(&tbl->entries) < READ_ONCE(tbl->gc_thresh1))
		goto out;

	for (i = 0 ; i < (1 << nht->hash_shift); i++) {
		neigh_for_each_in_bucket_safe(n, tmp, &nht->hash_heads[i]) {
			unsigned int state;

			write_lock(&n->lock);

			state = n->nud_state;
			if ((state & (NUD_PERMANENT | NUD_IN_TIMER)) ||
			    (n->flags &
			     (NTF_EXT_LEARNED | NTF_EXT_VALIDATED))) {
				write_unlock(&n->lock);
				continue;
			}

			if (time_before(n->used, n->confirmed) &&
			    time_is_before_eq_jiffies(n->confirmed))
				n->used = n->confirmed;

			if (refcount_read(&n->refcnt) == 1 &&
			    (state == NUD_FAILED ||
			     !time_in_range_open(jiffies, n->used,
						 n->used + NEIGH_VAR(n->parms, GC_STALETIME)))) {
				hlist_del_rcu(&n->hash);
				hlist_del_rcu(&n->dev_list);
				neigh_mark_dead(n);
				write_unlock(&n->lock);
				neigh_cleanup_and_release(n);
				continue;
			}
			write_unlock(&n->lock);
		}
		/*
		 * It's fine to release lock here, even if hash table
		 * grows while we are preempted.
		 */
		spin_unlock_bh(&tbl->lock);
		cond_resched();
		spin_lock_bh(&tbl->lock);
		nht = rcu_dereference_protected(tbl->nht,
						lockdep_is_held(&tbl->lock));
	}
out:
	/* Cycle through all hash buckets every BASE_REACHABLE_TIME/2 ticks.
	 * ARP entry timeouts range from 1/2 BASE_REACHABLE_TIME to 3/2
	 * BASE_REACHABLE_TIME.
	 */
	queue_delayed_work(system_power_efficient_wq, &tbl->gc_work,
			      NEIGH_VAR(&tbl->parms, BASE_REACHABLE_TIME) >> 1);
	spin_unlock_bh(&tbl->lock);
}

static __inline__ int neigh_max_probes(struct neighbour *n)
{
	struct neigh_parms *p = n->parms;
	return NEIGH_VAR(p, UCAST_PROBES) + NEIGH_VAR(p, APP_PROBES) +
	       (n->nud_state & NUD_PROBE ? NEIGH_VAR(p, MCAST_REPROBES) :
	        NEIGH_VAR(p, MCAST_PROBES));
}

static void neigh_invalidate(struct neighbour *neigh)
	__releases(neigh->lock)
	__acquires(neigh->lock)
{
	struct sk_buff *skb;

	NEIGH_CACHE_STAT_INC(neigh->tbl, res_failed);
	neigh_dbg(2, "neigh %p is failed\n", neigh);
	neigh->updated = jiffies;

	/* It is very thin place. report_unreachable is very complicated
	   routine. Particularly, it can hit the same neighbour entry!

	   So that, we try to be accurate and avoid dead loop. --ANK
	 */
	while (neigh->nud_state == NUD_FAILED &&
	       (skb = __skb_dequeue(&neigh->arp_queue)) != NULL) {
		write_unlock(&neigh->lock);
		neigh->ops->error_report(neigh, skb);
		write_lock(&neigh->lock);
	}
	__skb_queue_purge(&neigh->arp_queue);
	neigh->arp_queue_len_bytes = 0;
}

static void neigh_probe(struct neighbour *neigh)
	__releases(neigh->lock)
{
	struct sk_buff *skb = skb_peek_tail(&neigh->arp_queue);
	/* keep skb alive even if arp_queue overflows */
	if (skb)
		skb = skb_clone(skb, GFP_ATOMIC);
	write_unlock(&neigh->lock);
	if (neigh->ops->solicit)
		neigh->ops->solicit(neigh, skb);
	atomic_inc(&neigh->probes);
	consume_skb(skb);
}

/* Called when a timer expires for a neighbour entry. */

static void neigh_timer_handler(struct timer_list *t)
{
	unsigned long now, next;
	struct neighbour *neigh = timer_container_of(neigh, t, timer);
	bool skip_probe = false;
	unsigned int state;
	int notify = 0;

	write_lock(&neigh->lock);

	state = neigh->nud_state;
	now = jiffies;
	next = now + HZ;

	if (!(state & NUD_IN_TIMER))
		goto out;

	if (state & NUD_REACHABLE) {
		if (time_before_eq(now,
				   neigh->confirmed + neigh->parms->reachable_time)) {
			neigh_dbg(2, "neigh %p is still alive\n", neigh);
			next = neigh->confirmed + neigh->parms->reachable_time;
		} else if (time_before_eq(now,
					  neigh->used +
					  NEIGH_VAR(neigh->parms, DELAY_PROBE_TIME))) {
			neigh_dbg(2, "neigh %p is delayed\n", neigh);
			WRITE_ONCE(neigh->nud_state, NUD_DELAY);
			neigh->updated = jiffies;
			neigh_suspect(neigh);
			next = now + NEIGH_VAR(neigh->parms, DELAY_PROBE_TIME);
		} else {
			neigh_dbg(2, "neigh %p is suspected\n", neigh);
			WRITE_ONCE(neigh->nud_state, NUD_STALE);
			neigh->updated = jiffies;
			neigh_suspect(neigh);
			notify = 1;
		}
	} else if (state & NUD_DELAY) {
		if (time_before_eq(now,
				   neigh->confirmed +
				   NEIGH_VAR(neigh->parms, DELAY_PROBE_TIME))) {
			neigh_dbg(2, "neigh %p is now reachable\n", neigh);
			WRITE_ONCE(neigh->nud_state, NUD_REACHABLE);
			neigh->updated = jiffies;
			neigh_connect(neigh);
			notify = 1;
			next = neigh->confirmed + neigh->parms->reachable_time;
		} else {
			neigh_dbg(2, "neigh %p is probed\n", neigh);
			WRITE_ONCE(neigh->nud_state, NUD_PROBE);
			neigh->updated = jiffies;
			atomic_set(&neigh->probes, 0);
			notify = 1;
			next = now + max(NEIGH_VAR(neigh->parms, RETRANS_TIME),
					 HZ/100);
		}
	} else {
		/* NUD_PROBE|NUD_INCOMPLETE */
		next = now + max(NEIGH_VAR(neigh->parms, RETRANS_TIME), HZ/100);
	}

	if ((neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) &&
	    atomic_read(&neigh->probes) >= neigh_max_probes(neigh)) {
		if (neigh->nud_state == NUD_PROBE &&
		    neigh->flags & NTF_EXT_VALIDATED) {
			WRITE_ONCE(neigh->nud_state, NUD_STALE);
			neigh->updated = jiffies;
		} else {
			WRITE_ONCE(neigh->nud_state, NUD_FAILED);
			neigh_invalidate(neigh);
		}
		notify = 1;
		skip_probe = true;
	}

	if (notify)
		__neigh_notify(neigh, RTM_NEWNEIGH, 0, 0);

	if (skip_probe)
		goto out;

	if (neigh->nud_state & NUD_IN_TIMER) {
		if (time_before(next, jiffies + HZ/100))
			next = jiffies + HZ/100;
		if (!mod_timer(&neigh->timer, next))
			neigh_hold(neigh);
	}
	if (neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) {
		neigh_probe(neigh);
	} else {
out:
		write_unlock(&neigh->lock);
	}

	if (notify)
		call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);

	trace_neigh_timer_handler(neigh, 0);

	neigh_release(neigh);
}

int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb,
		       const bool immediate_ok)
{
	int rc;
	bool immediate_probe = false;

	write_lock_bh(&neigh->lock);

	rc = 0;
	if (neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE))
		goto out_unlock_bh;
	if (neigh->dead)
		goto out_dead;

	if (!(neigh->nud_state & (NUD_STALE | NUD_INCOMPLETE))) {
		if (NEIGH_VAR(neigh->parms, MCAST_PROBES) +
		    NEIGH_VAR(neigh->parms, APP_PROBES)) {
			unsigned long next, now = jiffies;

			atomic_set(&neigh->probes,
				   NEIGH_VAR(neigh->parms, UCAST_PROBES));
			neigh_del_timer(neigh);
			WRITE_ONCE(neigh->nud_state, NUD_INCOMPLETE);
			neigh->updated = now;
			if (!immediate_ok) {
				next = now + 1;
			} else {
				immediate_probe = true;
				next = now + max(NEIGH_VAR(neigh->parms,
							   RETRANS_TIME),
						 HZ / 100);
			}
			neigh_add_timer(neigh, next);
		} else {
			WRITE_ONCE(neigh->nud_state, NUD_FAILED);
			neigh->updated = jiffies;
			write_unlock_bh(&neigh->lock);

			kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_FAILED);
			return 1;
		}
	} else if (neigh->nud_state & NUD_STALE) {
		neigh_dbg(2, "neigh %p is delayed\n", neigh);
		neigh_del_timer(neigh);
		WRITE_ONCE(neigh->nud_state, NUD_DELAY);
		neigh->updated = jiffies;
		neigh_add_timer(neigh, jiffies +
				NEIGH_VAR(neigh->parms, DELAY_PROBE_TIME));
	}

	if (neigh->nud_state == NUD_INCOMPLETE) {
		if (skb) {
			while (neigh->arp_queue_len_bytes + skb->truesize >
			       NEIGH_VAR(neigh->parms, QUEUE_LEN_BYTES)) {
				struct sk_buff *buff;

				buff = __skb_dequeue(&neigh->arp_queue);
				if (!buff)
					break;
				neigh->arp_queue_len_bytes -= buff->truesize;
				kfree_skb_reason(buff, SKB_DROP_REASON_NEIGH_QUEUEFULL);
				NEIGH_CACHE_STAT_INC(neigh->tbl, unres_discards);
			}
			skb_dst_force(skb);
			__skb_queue_tail(&neigh->arp_queue, skb);
			neigh->arp_queue_len_bytes += skb->truesize;
		}
		rc = 1;
	}
out_unlock_bh:
	if (immediate_probe)
		neigh_probe(neigh);
	else
		write_unlock(&neigh->lock);
	local_bh_enable();
	trace_neigh_event_send_done(neigh, rc);
	return rc;

out_dead:
	if (neigh->nud_state & NUD_STALE)
		goto out_unlock_bh;
	write_unlock_bh(&neigh->lock);
	kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_DEAD);
	trace_neigh_event_send_dead(neigh, 1);
	return 1;
}
EXPORT_SYMBOL(__neigh_event_send);

static void neigh_update_hhs(struct neighbour *neigh)
{
	struct hh_cache *hh;
	void (*update)(struct hh_cache*, const struct net_device*, const unsigned char *)
		= NULL;

	if (neigh->dev->header_ops)
		update = neigh->dev->header_ops->cache_update;

	if (update) {
		hh = &neigh->hh;
		if (READ_ONCE(hh->hh_len)) {
			write_seqlock_bh(&hh->hh_lock);
			update(hh, neigh->dev, neigh->ha);
			write_sequnlock_bh(&hh->hh_lock);
		}
	}
}

static void neigh_update_process_arp_queue(struct neighbour *neigh)
	__releases(neigh->lock)
	__acquires(neigh->lock)
{
	struct sk_buff *skb;

	/* Again: avoid deadlock if something went wrong. */
	while (neigh->nud_state & NUD_VALID &&
	       (skb = __skb_dequeue(&neigh->arp_queue)) != NULL) {
		struct dst_entry *dst = skb_dst(skb);
		struct neighbour *n2, *n1 = neigh;

		write_unlock_bh(&neigh->lock);

		rcu_read_lock();

		/* Why not just use 'neigh' as-is?  The problem is that
		 * things such as shaper, eql, and sch_teql can end up
		 * using alternative, different, neigh objects to output
		 * the packet in the output path.  So what we need to do
		 * here is re-lookup the top-level neigh in the path so
		 * we can reinject the packet there.
		 */
		n2 = NULL;
		if (dst &&
		    READ_ONCE(dst->obsolete) != DST_OBSOLETE_DEAD) {
			n2 = dst_neigh_lookup_skb(dst, skb);
			if (n2)
				n1 = n2;
		}
		READ_ONCE(n1->output)(n1, skb);
		if (n2)
			neigh_release(n2);
		rcu_read_unlock();

		write_lock_bh(&neigh->lock);
	}
	__skb_queue_purge(&neigh->arp_queue);
	neigh->arp_queue_len_bytes = 0;
}

/* Generic update routine.
   -- lladdr is new lladdr or NULL, if it is not supplied.
   -- new    is new state.
   -- flags
	NEIGH_UPDATE_F_OVERRIDE allows to override existing lladdr,
				if it is different.
	NEIGH_UPDATE_F_WEAK_OVERRIDE will suspect existing "connected"
				lladdr instead of overriding it
				if it is different.
	NEIGH_UPDATE_F_ADMIN	means that the change is administrative.
	NEIGH_UPDATE_F_USE	means that the entry is user triggered.
	NEIGH_UPDATE_F_MANAGED	means that the entry will be auto-refreshed.
	NEIGH_UPDATE_F_OVERRIDE_ISROUTER allows to override existing
				NTF_ROUTER flag.
	NEIGH_UPDATE_F_ISROUTER	indicates if the neighbour is known as
				a router.
	NEIGH_UPDATE_F_EXT_VALIDATED means that the entry will not be removed
				or invalidated.

   Caller MUST hold reference count on the entry.
 */
static int __neigh_update(struct neighbour *neigh, const u8 *lladdr,
			  u8 new, u32 flags, u32 nlmsg_pid,
			  struct netlink_ext_ack *extack)
{
	bool gc_update = false, managed_update = false;
	bool process_arp_queue = false;
	int update_isrouter = 0;
	struct net_device *dev;
	int err, notify = 0;
	u8 old;

	trace_neigh_update(neigh, lladdr, new, flags, nlmsg_pid);

	write_lock_bh(&neigh->lock);

	dev    = neigh->dev;
	old    = neigh->nud_state;
	err    = -EPERM;

	if (neigh->dead) {
		NL_SET_ERR_MSG(extack, "Neighbor entry is now dead");
		new = old;
		goto out;
	}
	if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
	    (old & (NUD_NOARP | NUD_PERMANENT)))
		goto out;

	neigh_update_flags(neigh, flags, &notify, &gc_update, &managed_update);
	if (flags & (NEIGH_UPDATE_F_USE | NEIGH_UPDATE_F_MANAGED)) {
		new = old & ~NUD_PERMANENT;
		WRITE_ONCE(neigh->nud_state, new);
		err = 0;
		goto out;
	}

	if (!(new & NUD_VALID)) {
		neigh_del_timer(neigh);
		if (old & NUD_CONNECTED)
			neigh_suspect(neigh);
		WRITE_ONCE(neigh->nud_state, new);
		err = 0;
		notify = old & NUD_VALID;
		if ((old & (NUD_INCOMPLETE | NUD_PROBE)) &&
		    (new & NUD_FAILED)) {
			neigh_invalidate(neigh);
			notify = 1;
		}
		goto out;
	}

	/* Compare new lladdr with cached one */
	if (!dev->addr_len) {
		/* First case: device needs no address. */
		lladdr = neigh->ha;
	} else if (lladdr) {
		/* The second case: if something is already cached
		   and a new address is proposed:
		   - compare new & old
		   - if they are different, check override flag
		 */
		if ((old & NUD_VALID) &&
		    !memcmp(lladdr, neigh->ha, dev->addr_len))
			lladdr = neigh->ha;
	} else {
		/* No address is supplied; if we know something,
		   use it, otherwise discard the request.
		 */
		err = -EINVAL;
		if (!(old & NUD_VALID)) {
			NL_SET_ERR_MSG(extack, "No link layer address given");
			goto out;
		}
		lladdr = neigh->ha;
	}

	/* Update confirmed timestamp for neighbour entry after we
	 * received ARP packet even if it doesn't change IP to MAC binding.
	 */
	if (new & NUD_CONNECTED)
		neigh->confirmed = jiffies;

	/* If entry was valid and address is not changed,
	   do not change entry state, if new one is STALE.
	 */
	err = 0;
	update_isrouter = flags & NEIGH_UPDATE_F_OVERRIDE_ISROUTER;
	if (old & NUD_VALID) {
		if (lladdr != neigh->ha && !(flags & NEIGH_UPDATE_F_OVERRIDE)) {
			update_isrouter = 0;
			if ((flags & NEIGH_UPDATE_F_WEAK_OVERRIDE) &&
			    (old & NUD_CONNECTED)) {
				lladdr = neigh->ha;
				new = NUD_STALE;
			} else
				goto out;
		} else {
			if (lladdr == neigh->ha && new == NUD_STALE &&
			    !(flags & NEIGH_UPDATE_F_ADMIN))
				new = old;
		}
	}

	/* Update timestamp only once we know we will make a change to the
	 * neighbour entry. Otherwise we risk to move the locktime window with
	 * noop updates and ignore relevant ARP updates.
	 */
	if (new != old || lladdr != neigh->ha)
		neigh->updated = jiffies;

	if (new != old) {
		neigh_del_timer(neigh);
		if (new & NUD_PROBE)
			atomic_set(&neigh->probes, 0);
		if (new & NUD_IN_TIMER)
			neigh_add_timer(neigh, (jiffies +
						((new & NUD_REACHABLE) ?
						 neigh->parms->reachable_time :
						 0)));
		WRITE_ONCE(neigh->nud_state, new);
		notify = 1;
	}

	if (lladdr != neigh->ha) {
		write_seqlock(&neigh->ha_lock);
		memcpy(&neigh->ha, lladdr, dev->addr_len);
		write_sequnlock(&neigh->ha_lock);
		neigh_update_hhs(neigh);
		if (!(new & NUD_CONNECTED))
			neigh->confirmed = jiffies -
				      (NEIGH_VAR(neigh->parms, BASE_REACHABLE_TIME) << 1);
		notify = 1;
	}
	if (new == old)
		goto out;
	if (new & NUD_CONNECTED)
		neigh_connect(neigh);
	else
		neigh_suspect(neigh);

	if (!(old & NUD_VALID))
		process_arp_queue = true;

out:
	if (update_isrouter)
		neigh_update_is_router(neigh, flags, &notify);

	if (notify)
		__neigh_notify(neigh, RTM_NEWNEIGH, 0, nlmsg_pid);

	if (process_arp_queue)
		neigh_update_process_arp_queue(neigh);

	write_unlock_bh(&neigh->lock);

	if (((new ^ old) & NUD_PERMANENT) || gc_update)
		neigh_update_gc_list(neigh);
	if (managed_update)
		neigh_update_managed_list(neigh);

	if (notify)
		call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);

	trace_neigh_update_done(neigh, err);
	return err;
}

int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
		 u32 flags, u32 nlmsg_pid)
{
	return __neigh_update(neigh, lladdr, new, flags, nlmsg_pid, NULL);
}
EXPORT_SYMBOL(neigh_update);

/* Update the neigh to listen temporarily for probe responses, even if it is
 * in a NUD_FAILED state. The caller has to hold neigh->lock for writing.
 */
void __neigh_set_probe_once(struct neighbour *neigh)
{
	if (neigh->dead)
		return;
	neigh->updated = jiffies;
	if (!(neigh->nud_state & NUD_FAILED))
		return;
	WRITE_ONCE(neigh->nud_state, NUD_INCOMPLETE);
	atomic_set(&neigh->probes, neigh_max_probes(neigh));
	neigh_add_timer(neigh,
			jiffies + max(NEIGH_VAR(neigh->parms, RETRANS_TIME),
				      HZ/100));
}
EXPORT_SYMBOL(__neigh_set_probe_once);

struct neighbour *neigh_event_ns(struct neigh_table *tbl,
				 u8 *lladdr, void *saddr,
				 struct net_device *dev)
{
	struct neighbour *neigh = __neigh_lookup(tbl, saddr, dev,
						 lladdr || !dev->addr_len);
	if (neigh)
		neigh_update(neigh, lladdr, NUD_STALE,
			     NEIGH_UPDATE_F_OVERRIDE, 0);
	return neigh;
}
EXPORT_SYMBOL(neigh_event_ns);

/* called with read_lock_bh(&n->lock); */
static void neigh_hh_init(struct neighbour *n)
{
	struct net_device *dev = n->dev;
	__be16 prot = n->tbl->protocol;
	struct hh_cache	*hh = &n->hh;

	write_lock_bh(&n->lock);

	/* Only one thread can come in here and initialize the
	 * hh_cache entry.
	 */
	if (!hh->hh_len)
		dev->header_ops->cache(n, hh, prot);

	write_unlock_bh(&n->lock);
}

/* Slow and careful. */

int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb)
{
	int rc = 0;

	if (!neigh_event_send(neigh, skb)) {
		int err;
		struct net_device *dev = neigh->dev;
		unsigned int seq;

		if (dev->header_ops->cache && !READ_ONCE(neigh->hh.hh_len))
			neigh_hh_init(neigh);

		do {
			__skb_pull(skb, skb_network_offset(skb));
			seq = read_seqbegin(&neigh->ha_lock);
			err = dev_hard_header(skb, dev, ntohs(skb->protocol),
					      neigh->ha, NULL, skb->len);
		} while (read_seqretry(&neigh->ha_lock, seq));

		if (err >= 0)
			rc = dev_queue_xmit(skb);
		else
			goto out_kfree_skb;
	}
out:
	return rc;
out_kfree_skb:
	rc = -EINVAL;
	kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_HH_FILLFAIL);
	goto out;
}
EXPORT_SYMBOL(neigh_resolve_output);

/* As fast as possible without hh cache */

int neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb)
{
	struct net_device *dev = neigh->dev;
	unsigned int seq;
	int err;

	do {
		__skb_pull(skb, skb_network_offset(skb));
		seq = read_seqbegin(&neigh->ha_lock);
		err = dev_hard_header(skb, dev, ntohs(skb->protocol),
				      neigh->ha, NULL, skb->len);
	} while (read_seqretry(&neigh->ha_lock, seq));

	if (err >= 0)
		err = dev_queue_xmit(skb);
	else {
		err = -EINVAL;
		kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_HH_FILLFAIL);
	}
	return err;
}
EXPORT_SYMBOL(neigh_connected_output);

int neigh_direct_output(struct neighbour *neigh, struct sk_buff *skb)
{
	return dev_queue_xmit(skb);
}
EXPORT_SYMBOL(neigh_direct_output);

static void neigh_managed_work(struct work_struct *work)
{
	struct neigh_table *tbl = container_of(work, struct neigh_table,
					       managed_work.work);
	struct neighbour *neigh;

	spin_lock_bh(&tbl->lock);
	list_for_each_entry(neigh, &tbl->managed_list, managed_list)
		neigh_event_send_probe(neigh, NULL, false);
	queue_delayed_work(system_power_efficient_wq, &tbl->managed_work,
			   NEIGH_VAR(&tbl->parms, INTERVAL_PROBE_TIME_MS));
	spin_unlock_bh(&tbl->lock);
}

static void neigh_proxy_process(struct timer_list *t)
{
	struct neigh_table *tbl = timer_container_of(tbl, t, proxy_timer);
	long sched_next = 0;
	unsigned long now = jiffies;
	struct sk_buff *skb, *n;

	spin_lock(&tbl->proxy_queue.lock);

	skb_queue_walk_safe(&tbl->proxy_queue, skb, n) {
		long tdif = NEIGH_CB(skb)->sched_next - now;

		if (tdif <= 0) {
			struct net_device *dev = skb->dev;

			neigh_parms_qlen_dec(dev, tbl->family);
			__skb_unlink(skb, &tbl->proxy_queue);

			if (tbl->proxy_redo && netif_running(dev)) {
				rcu_read_lock();
				tbl->proxy_redo(skb);
				rcu_read_unlock();
			} else {
				kfree_skb(skb);
			}

			dev_put(dev);
		} else if (!sched_next || tdif < sched_next)
			sched_next = tdif;
	}
	timer_delete(&tbl->proxy_timer);
	if (sched_next)
		mod_timer(&tbl->proxy_timer, jiffies + sched_next);
	spin_unlock(&tbl->proxy_queue.lock);
}

static unsigned long neigh_proxy_delay(struct neigh_parms *p)
{
	/* If proxy_delay is zero, do not call get_random_u32_below()
	 * as it is undefined behavior.
	 */
	unsigned long proxy_delay = NEIGH_VAR(p, PROXY_DELAY);

	return proxy_delay ?
	       jiffies + get_random_u32_below(proxy_delay) : jiffies;
}

void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
		    struct sk_buff *skb)
{
	unsigned long sched_next = neigh_proxy_delay(p);

	if (p->qlen > NEIGH_VAR(p, PROXY_QLEN)) {
		kfree_skb(skb);
		return;
	}

	NEIGH_CB(skb)->sched_next = sched_next;
	NEIGH_CB(skb)->flags |= LOCALLY_ENQUEUED;

	spin_lock(&tbl->proxy_queue.lock);
	if (timer_delete(&tbl->proxy_timer)) {
		if (time_before(tbl->proxy_timer.expires, sched_next))
			sched_next = tbl->proxy_timer.expires;
	}
	skb_dst_drop(skb);
	dev_hold(skb->dev);
	__skb_queue_tail(&tbl->proxy_queue, skb);
	p->qlen++;
	mod_timer(&tbl->proxy_timer, sched_next);
	spin_unlock(&tbl->proxy_queue.lock);
}
EXPORT_SYMBOL(pneigh_enqueue);

static inline struct neigh_parms *lookup_neigh_parms(struct neigh_table *tbl,
						      struct net *net, int ifindex)
{
	struct neigh_parms *p;

	list_for_each_entry(p, &tbl->parms_list, list) {
		if ((p->dev && p->dev->ifindex == ifindex && net_eq(neigh_parms_net(p), net)) ||
		    (!p->dev && !ifindex && net_eq(net, &init_net)))
			return p;
	}

	return NULL;
}

struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
				      struct neigh_table *tbl)
{
	struct neigh_parms *p;
	struct net *net = dev_net(dev);
	const struct net_device_ops *ops = dev->netdev_ops;

	p = kmemdup(&tbl->parms, sizeof(*p), GFP_KERNEL);
	if (p) {
		p->tbl		  = tbl;
		refcount_set(&p->refcnt, 1);
		neigh_set_reach_time(p);
		p->qlen = 0;
		netdev_hold(dev, &p->dev_tracker, GFP_KERNEL);
		p->dev = dev;
		write_pnet(&p->net, net);
		p->sysctl_table = NULL;

		if (ops->ndo_neigh_setup && ops->ndo_neigh_setup(dev, p)) {
			netdev_put(dev, &p->dev_tracker);
			kfree(p);
			return NULL;
		}

		spin_lock_bh(&tbl->lock);
		list_add_rcu(&p->list, &tbl->parms.list);
		spin_unlock_bh(&tbl->lock);

		neigh_parms_data_state_cleanall(p);
	}
	return p;
}
EXPORT_SYMBOL(neigh_parms_alloc);

static void neigh_rcu_free_parms(struct rcu_head *head)
{
	struct neigh_parms *parms =
		container_of(head, struct neigh_parms, rcu_head);

	neigh_parms_put(parms);
}

void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms)
{
	if (!parms || parms == &tbl->parms)
		return;

	spin_lock_bh(&tbl->lock);
	list_del_rcu(&parms->list);
	parms->dead = 1;
	spin_unlock_bh(&tbl->lock);

	netdev_put(parms->dev, &parms->dev_tracker);
	call_rcu(&parms->rcu_head, neigh_rcu_free_parms);
}
EXPORT_SYMBOL(neigh_parms_release);

static struct lock_class_key neigh_table_proxy_queue_class;

static struct neigh_table __rcu *neigh_tables[NEIGH_NR_TABLES] __read_mostly;

void neigh_table_init(int index, struct neigh_table *tbl)
{
	unsigned long now = jiffies;
	unsigned long phsize;

	INIT_LIST_HEAD(&tbl->parms_list);
	INIT_LIST_HEAD(&tbl->gc_list);
	INIT_LIST_HEAD(&tbl->managed_list);

	list_add(&tbl->parms.list, &tbl->parms_list);
	write_pnet(&tbl->parms.net, &init_net);
	refcount_set(&tbl->parms.refcnt, 1);
	neigh_set_reach_time(&tbl->parms);
	tbl->parms.qlen = 0;

	tbl->stats = alloc_percpu(struct neigh_statistics);
	if (!tbl->stats)
		panic("cannot create neighbour cache statistics");

#ifdef CONFIG_PROC_FS
	if (!proc_create_seq_data(tbl->id, 0, init_net.proc_net_stat,
			      &neigh_stat_seq_ops, tbl))
		panic("cannot create neighbour proc dir entry");
#endif

	RCU_INIT_POINTER(tbl->nht, neigh_hash_alloc(3));

	phsize = (PNEIGH_HASHMASK + 1) * sizeof(struct pneigh_entry *);
	tbl->phash_buckets = kzalloc(phsize, GFP_KERNEL);

	if (!tbl->nht || !tbl->phash_buckets)
		panic("cannot allocate neighbour cache hashes");

	if (!tbl->entry_size)
		tbl->entry_size = ALIGN(offsetof(struct neighbour, primary_key) +
					tbl->key_len, NEIGH_PRIV_ALIGN);
	else
		WARN_ON(tbl->entry_size % NEIGH_PRIV_ALIGN);

	spin_lock_init(&tbl->lock);
	mutex_init(&tbl->phash_lock);

	INIT_DEFERRABLE_WORK(&tbl->gc_work, neigh_periodic_work);
	queue_delayed_work(system_power_efficient_wq, &tbl->gc_work,
			tbl->parms.reachable_time);
	INIT_DEFERRABLE_WORK(&tbl->managed_work, neigh_managed_work);
	queue_delayed_work(system_power_efficient_wq, &tbl->managed_work, 0);

	timer_setup(&tbl->proxy_timer, neigh_proxy_process, 0);
	skb_queue_head_init_class(&tbl->proxy_queue,
			&neigh_table_proxy_queue_class);

	tbl->last_flush = now;
	tbl->last_rand	= now + tbl->parms.reachable_time * 20;

	rcu_assign_pointer(neigh_tables[index], tbl);
}
EXPORT_SYMBOL(neigh_table_init);

/*
 * Only called from ndisc_cleanup(), which means this is dead code
 * because we no longer can unload IPv6 module.
 */
int neigh_table_clear(int index, struct neigh_table *tbl)
{
	RCU_INIT_POINTER(neigh_tables[index], NULL);
	synchronize_rcu();

	/* It is not clean... Fix it to unload IPv6 module safely */
	cancel_delayed_work_sync(&tbl->managed_work);
	cancel_delayed_work_sync(&tbl->gc_work);
	timer_delete_sync(&tbl->proxy_timer);
	pneigh_queue_purge(&tbl->proxy_queue, NULL, tbl->family);
	neigh_ifdown(tbl, NULL);
	if (atomic_read(&tbl->entries))
		pr_crit("neighbour leakage\n");

	call_rcu(&rcu_dereference_protected(tbl->nht, 1)->rcu,
		 neigh_hash_free_rcu);
	tbl->nht = NULL;

	kfree(tbl->phash_buckets);
	tbl->phash_buckets = NULL;

	remove_proc_entry(tbl->id, init_net.proc_net_stat);

	free_percpu(tbl->stats);
	tbl->stats = NULL;

	return 0;
}
EXPORT_SYMBOL(neigh_table_clear);

static struct neigh_table *neigh_find_table(int family)
{
	struct neigh_table *tbl = NULL;

	switch (family) {
	case AF_INET:
		tbl = rcu_dereference_rtnl(neigh_tables[NEIGH_ARP_TABLE]);
		break;
	case AF_INET6:
		tbl = rcu_dereference_rtnl(neigh_tables[NEIGH_ND_TABLE]);
		break;
	}

	return tbl;
}

const struct nla_policy nda_policy[NDA_MAX+1] = {
	[NDA_UNSPEC]		= { .strict_start_type = NDA_NH_ID },
	[NDA_DST]		= { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
	[NDA_LLADDR]		= { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
	[NDA_CACHEINFO]		= { .len = sizeof(struct nda_cacheinfo) },
	[NDA_PROBES]		= { .type = NLA_U32 },
	[NDA_VLAN]		= { .type = NLA_U16 },
	[NDA_PORT]		= { .type = NLA_U16 },
	[NDA_VNI]		= { .type = NLA_U32 },
	[NDA_IFINDEX]		= { .type = NLA_U32 },
	[NDA_MASTER]		= { .type = NLA_U32 },
	[NDA_PROTOCOL]		= { .type = NLA_U8 },
	[NDA_NH_ID]		= { .type = NLA_U32 },
	[NDA_FLAGS_EXT]		= NLA_POLICY_MASK(NLA_U32, NTF_EXT_MASK),
	[NDA_FDB_EXT_ATTRS]	= { .type = NLA_NESTED },
};

static int neigh_delete(struct sk_buff *skb, struct nlmsghdr *nlh,
			struct netlink_ext_ack *extack)
{
	struct net *net = sock_net(skb->sk);
	struct ndmsg *ndm;
	struct nlattr *dst_attr;
	struct neigh_table *tbl;
	struct neighbour *neigh;
	struct net_device *dev = NULL;
	int err = -EINVAL;

	ASSERT_RTNL();
	if (nlmsg_len(nlh) < sizeof(*ndm))
		goto out;

	dst_attr = nlmsg_find_attr(nlh, sizeof(*ndm), NDA_DST);
	if (!dst_attr) {
		NL_SET_ERR_MSG(extack, "Network address not specified");
		goto out;
	}

	ndm = nlmsg_data(nlh);
	if (ndm->ndm_ifindex) {
		dev = __dev_get_by_index(net, ndm->ndm_ifindex);
		if (dev == NULL) {
			err = -ENODEV;
			goto out;
		}
	}

	tbl = neigh_find_table(ndm->ndm_family);
	if (tbl == NULL)
		return -EAFNOSUPPORT;

	if (nla_len(dst_attr) < (int)tbl->key_len) {
		NL_SET_ERR_MSG(extack, "Invalid network address");
		goto out;
	}

	if (ndm->ndm_flags & NTF_PROXY) {
		err = pneigh_delete(tbl, net, nla_data(dst_attr), dev);
		goto out;
	}

	if (dev == NULL)
		goto out;

	neigh = neigh_lookup(tbl, nla_data(dst_attr), dev);
	if (neigh == NULL) {
		err = -ENOENT;
		goto out;
	}

	err = __neigh_update(neigh, NULL, NUD_FAILED,
			     NEIGH_UPDATE_F_OVERRIDE | NEIGH_UPDATE_F_ADMIN,
			     NETLINK_CB(skb).portid, extack);
	spin_lock_bh(&tbl->lock);
	neigh_release(neigh);
	neigh_remove_one(neigh);
	spin_unlock_bh(&tbl->lock);

out:
	return err;
}

static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh,
		     struct netlink_ext_ack *extack)
{
	int flags = NEIGH_UPDATE_F_ADMIN | NEIGH_UPDATE_F_OVERRIDE |
		    NEIGH_UPDATE_F_OVERRIDE_ISROUTER;
	struct net *net = sock_net(skb->sk);
	struct ndmsg *ndm;
	struct nlattr *tb[NDA_MAX+1];
	struct neigh_table *tbl;
	struct net_device *dev = NULL;
	struct neighbour *neigh;
	void *dst, *lladdr;
	u8 protocol = 0;
	u32 ndm_flags;
	int err;

	ASSERT_RTNL();
	err = nlmsg_parse_deprecated(nlh, sizeof(*ndm), tb, NDA_MAX,
				     nda_policy, extack);
	if (err < 0)
		goto out;

	err = -EINVAL;
	if (!tb[NDA_DST]) {
		NL_SET_ERR_MSG(extack, "Network address not specified");
		goto out;
	}

	ndm = nlmsg_data(nlh);
	ndm_flags = ndm->ndm_flags;
	if (tb[NDA_FLAGS_EXT]) {
		u32 ext = nla_get_u32(tb[NDA_FLAGS_EXT]);

		BUILD_BUG_ON(sizeof(neigh->flags) * BITS_PER_BYTE <
			     (sizeof(ndm->ndm_flags) * BITS_PER_BYTE +
			      hweight32(NTF_EXT_MASK)));
		ndm_flags |= (ext << NTF_EXT_SHIFT);
	}
	if (ndm->ndm_ifindex) {
		dev = __dev_get_by_index(net, ndm->ndm_ifindex);
		if (dev == NULL) {
			err = -ENODEV;
			goto out;
		}

		if (tb[NDA_LLADDR] && nla_len(tb[NDA_LLADDR]) < dev->addr_len) {
			NL_SET_ERR_MSG(extack, "Invalid link address");
			goto out;
		}
	}

	tbl = neigh_find_table(ndm->ndm_family);
	if (tbl == NULL)
		return -EAFNOSUPPORT;

	if (nla_len(tb[NDA_DST]) < (int)tbl->key_len) {
		NL_SET_ERR_MSG(extack, "Invalid network address");
		goto out;
	}

	dst = nla_data(tb[NDA_DST]);
	lladdr = tb[NDA_LLADDR] ? nla_data(tb[NDA_LLADDR]) : NULL;

	if (tb[NDA_PROTOCOL])
		protocol = nla_get_u8(tb[NDA_PROTOCOL]);
	if (ndm_flags & NTF_PROXY) {
		if (ndm_flags & (NTF_MANAGED | NTF_EXT_VALIDATED)) {
			NL_SET_ERR_MSG(extack, "Invalid NTF_* flag combination");
			goto out;
		}

		err = pneigh_create(tbl, net, dst, dev, ndm_flags, protocol,
				    !!(ndm->ndm_state & NUD_PERMANENT));
		goto out;
	}

	if (!dev) {
		NL_SET_ERR_MSG(extack, "Device not specified");
		goto out;
	}

	if (tbl->allow_add && !tbl->allow_add(dev, extack)) {
		err = -EINVAL;
		goto out;
	}

	neigh = neigh_lookup(tbl, dst, dev);
	if (neigh == NULL) {
		bool ndm_permanent  = ndm->ndm_state & NUD_PERMANENT;
		bool exempt_from_gc = ndm_permanent ||
				      ndm_flags & (NTF_EXT_LEARNED |
						   NTF_EXT_VALIDATED);

		if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
			err = -ENOENT;
			goto out;
		}
		if (ndm_permanent && (ndm_flags & NTF_MANAGED)) {
			NL_SET_ERR_MSG(extack, "Invalid NTF_* flag for permanent entry");
			err = -EINVAL;
			goto out;
		}
		if (ndm_flags & NTF_EXT_VALIDATED) {
			u8 state = ndm->ndm_state;

			/* NTF_USE and NTF_MANAGED will result in the neighbor
			 * being created with an invalid state (NUD_NONE).
			 */
			if (ndm_flags & (NTF_USE | NTF_MANAGED))
				state = NUD_NONE;

			if (!(state & NUD_VALID)) {
				NL_SET_ERR_MSG(extack,
					       "Cannot create externally validated neighbor with an invalid state");
				err = -EINVAL;
				goto out;
			}
		}

		neigh = ___neigh_create(tbl, dst, dev,
					ndm_flags &
					(NTF_EXT_LEARNED | NTF_MANAGED |
					 NTF_EXT_VALIDATED),
					exempt_from_gc, true);
		if (IS_ERR(neigh)) {
			err = PTR_ERR(neigh);
			goto out;
		}
	} else {
		if (nlh->nlmsg_flags & NLM_F_EXCL) {
			err = -EEXIST;
			neigh_release(neigh);
			goto out;
		}
		if (ndm_flags & NTF_EXT_VALIDATED) {
			u8 state = ndm->ndm_state;

			/* NTF_USE and NTF_MANAGED do not update the existing
			 * state other than clearing it if it was
			 * NUD_PERMANENT.
			 */
			if (ndm_flags & (NTF_USE | NTF_MANAGED))
				state = READ_ONCE(neigh->nud_state) & ~NUD_PERMANENT;

			if (!(state & NUD_VALID)) {
				NL_SET_ERR_MSG(extack,
					       "Cannot mark neighbor as externally validated with an invalid state");
				err = -EINVAL;
				neigh_release(neigh);
				goto out;
			}
		}

		if (!(nlh->nlmsg_flags & NLM_F_REPLACE))
			flags &= ~(NEIGH_UPDATE_F_OVERRIDE |
				   NEIGH_UPDATE_F_OVERRIDE_ISROUTER);
	}

	if (protocol)
		neigh->protocol = protocol;
	if (ndm_flags & NTF_EXT_LEARNED)
		flags |= NEIGH_UPDATE_F_EXT_LEARNED;
	if (ndm_flags & NTF_ROUTER)
		flags |= NEIGH_UPDATE_F_ISROUTER;
	if (ndm_flags & NTF_MANAGED)
		flags |= NEIGH_UPDATE_F_MANAGED;
	if (ndm_flags & NTF_USE)
		flags |= NEIGH_UPDATE_F_USE;
	if (ndm_flags & NTF_EXT_VALIDATED)
		flags |= NEIGH_UPDATE_F_EXT_VALIDATED;

	err = __neigh_update(neigh, lladdr, ndm->ndm_state, flags,
			     NETLINK_CB(skb).portid, extack);
	if (!err && ndm_flags & (NTF_USE | NTF_MANAGED))
		neigh_event_send(neigh, NULL);
	neigh_release(neigh);
out:
	return err;
}

static int neightbl_fill_parms(struct sk_buff *skb, struct neigh_parms *parms)
{
	struct nlattr *nest;

	nest = nla_nest_start_noflag(skb, NDTA_PARMS);
	if (nest == NULL)
		return -ENOBUFS;

	if ((parms->dev &&
	     nla_put_u32(skb, NDTPA_IFINDEX, READ_ONCE(parms->dev->ifindex))) ||
	    nla_put_u32(skb, NDTPA_REFCNT, refcount_read(&parms->refcnt)) ||
	    nla_put_u32(skb, NDTPA_QUEUE_LENBYTES,
			NEIGH_VAR(parms, QUEUE_LEN_BYTES)) ||
	    /* approximative value for deprecated QUEUE_LEN (in packets) */
	    nla_put_u32(skb, NDTPA_QUEUE_LEN,
			NEIGH_VAR(parms, QUEUE_LEN_BYTES) / SKB_TRUESIZE(ETH_FRAME_LEN)) ||
	    nla_put_u32(skb, NDTPA_PROXY_QLEN, NEIGH_VAR(parms, PROXY_QLEN)) ||
	    nla_put_u32(skb, NDTPA_APP_PROBES, NEIGH_VAR(parms, APP_PROBES)) ||
	    nla_put_u32(skb, NDTPA_UCAST_PROBES,
			NEIGH_VAR(parms, UCAST_PROBES)) ||
	    nla_put_u32(skb, NDTPA_MCAST_PROBES,
			NEIGH_VAR(parms, MCAST_PROBES)) ||
	    nla_put_u32(skb, NDTPA_MCAST_REPROBES,
			NEIGH_VAR(parms, MCAST_REPROBES)) ||
	    nla_put_msecs(skb, NDTPA_REACHABLE_TIME, READ_ONCE(parms->reachable_time),
			  NDTPA_PAD) ||
	    nla_put_msecs(skb, NDTPA_BASE_REACHABLE_TIME,
			  NEIGH_VAR(parms, BASE_REACHABLE_TIME), NDTPA_PAD) ||
	    nla_put_msecs(skb, NDTPA_GC_STALETIME,
			  NEIGH_VAR(parms, GC_STALETIME), NDTPA_PAD) ||
	    nla_put_msecs(skb, NDTPA_DELAY_PROBE_TIME,
			  NEIGH_VAR(parms, DELAY_PROBE_TIME), NDTPA_PAD) ||
	    nla_put_msecs(skb, NDTPA_RETRANS_TIME,
			  NEIGH_VAR(parms, RETRANS_TIME), NDTPA_PAD) ||
	    nla_put_msecs(skb, NDTPA_ANYCAST_DELAY,
			  NEIGH_VAR(parms, ANYCAST_DELAY), NDTPA_PAD) ||
	    nla_put_msecs(skb, NDTPA_PROXY_DELAY,
			  NEIGH_VAR(parms, PROXY_DELAY), NDTPA_PAD) ||
	    nla_put_msecs(skb, NDTPA_LOCKTIME,
			  NEIGH_VAR(parms, LOCKTIME), NDTPA_PAD) ||
	    nla_put_msecs(skb, NDTPA_INTERVAL_PROBE_TIME_MS,
			  NEIGH_VAR(parms, INTERVAL_PROBE_TIME_MS), NDTPA_PAD))
		goto nla_put_failure;
	return nla_nest_end(skb, nest);

nla_put_failure:
	nla_nest_cancel(skb, nest);
	return -EMSGSIZE;
}

static int neightbl_fill_info(struct sk_buff *skb, struct neigh_table *tbl,
			      u32 pid, u32 seq, int type, int flags)
{
	struct nlmsghdr *nlh;
	struct ndtmsg *ndtmsg;

	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ndtmsg), flags);
	if (nlh == NULL)
		return -EMSGSIZE;

	ndtmsg = nlmsg_data(nlh);
	ndtmsg->ndtm_family = tbl->family;
	ndtmsg->ndtm_pad1   = 0;
	ndtmsg->ndtm_pad2   = 0;

	if (nla_put_string(skb, NDTA_NAME, tbl->id) ||
	    nla_put_msecs(skb, NDTA_GC_INTERVAL, READ_ONCE(tbl->gc_interval),
			  NDTA_PAD) ||
	    nla_put_u32(skb, NDTA_THRESH1, READ_ONCE(tbl->gc_thresh1)) ||
	    nla_put_u32(skb, NDTA_THRESH2, READ_ONCE(tbl->gc_thresh2)) ||
	    nla_put_u32(skb, NDTA_THRESH3, READ_ONCE(tbl->gc_thresh3)))
		goto nla_put_failure;
	{
		unsigned long now = jiffies;
		long flush_delta = now - READ_ONCE(tbl->last_flush);
		long rand_delta = now - READ_ONCE(tbl->last_rand);
		struct neigh_hash_table *nht;
		struct ndt_config ndc = {
			.ndtc_key_len		= tbl->key_len,
			.ndtc_entry_size	= tbl->entry_size,
			.ndtc_entries		= atomic_read(&tbl->entries),
			.ndtc_last_flush	= jiffies_to_msecs(flush_delta),
			.ndtc_last_rand		= jiffies_to_msecs(rand_delta),
			.ndtc_proxy_qlen	= READ_ONCE(tbl->proxy_queue.qlen),
		};

		nht = rcu_dereference(tbl->nht);
		ndc.ndtc_hash_rnd = nht->hash_rnd[0];
		ndc.ndtc_hash_mask = ((1 << nht->hash_shift) - 1);

		if (nla_put(skb, NDTA_CONFIG, sizeof(ndc), &ndc))
			goto nla_put_failure;
	}

	{
		int cpu;
		struct ndt_stats ndst;

		memset(&ndst, 0, sizeof(ndst));

		for_each_possible_cpu(cpu) {
			struct neigh_statistics	*st;

			st = per_cpu_ptr(tbl->stats, cpu);
			ndst.ndts_allocs		+= READ_ONCE(st->allocs);
			ndst.ndts_destroys		+= READ_ONCE(st->destroys);
			ndst.ndts_hash_grows		+= READ_ONCE(st->hash_grows);
			ndst.ndts_res_failed		+= READ_ONCE(st->res_failed);
			ndst.ndts_lookups		+= READ_ONCE(st->lookups);
			ndst.ndts_hits			+= READ_ONCE(st->hits);
			ndst.ndts_rcv_probes_mcast	+= READ_ONCE(st->rcv_probes_mcast);
			ndst.ndts_rcv_probes_ucast	+= READ_ONCE(st->rcv_probes_ucast);
			ndst.ndts_periodic_gc_runs	+= READ_ONCE(st->periodic_gc_runs);
			ndst.ndts_forced_gc_runs	+= READ_ONCE(st->forced_gc_runs);
			ndst.ndts_table_fulls		+= READ_ONCE(st->table_fulls);
		}

		if (nla_put_64bit(skb, NDTA_STATS, sizeof(ndst), &ndst,
				  NDTA_PAD))
			goto nla_put_failure;
	}

	BUG_ON(tbl->parms.dev);
	if (neightbl_fill_parms(skb, &tbl->parms) < 0)
		goto nla_put_failure;

	nlmsg_end(skb, nlh);
	return 0;

nla_put_failure:
	nlmsg_cancel(skb, nlh);
	return -EMSGSIZE;
}

static int neightbl_fill_param_info(struct sk_buff *skb,
				    struct neigh_table *tbl,
				    struct neigh_parms *parms,
				    u32 pid, u32 seq, int type,
				    unsigned int flags)
{
	struct ndtmsg *ndtmsg;
	struct nlmsghdr *nlh;

	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ndtmsg), flags);
	if (nlh == NULL)
		return -EMSGSIZE;

	ndtmsg = nlmsg_data(nlh);
	ndtmsg->ndtm_family = tbl->family;
	ndtmsg->ndtm_pad1   = 0;
	ndtmsg->ndtm_pad2   = 0;

	if (nla_put_string(skb, NDTA_NAME, tbl->id) < 0 ||
	    neightbl_fill_parms(skb, parms) < 0)
		goto errout;

	nlmsg_end(skb, nlh);
	return 0;
errout:
	nlmsg_cancel(skb, nlh);
	return -EMSGSIZE;
}

static const struct nla_policy nl_neightbl_policy[NDTA_MAX+1] = {
	[NDTA_NAME]		= { .type = NLA_STRING },
	[NDTA_THRESH1]		= { .type = NLA_U32 },
	[NDTA_THRESH2]		= { .type = NLA_U32 },
	[NDTA_THRESH3]		= { .type = NLA_U32 },
	[NDTA_GC_INTERVAL]	= { .type = NLA_U64 },
	[NDTA_PARMS]		= { .type = NLA_NESTED },
};

static const struct nla_policy nl_ntbl_parm_policy[NDTPA_MAX+1] = {
	[NDTPA_IFINDEX]			= { .type = NLA_U32 },
	[NDTPA_QUEUE_LEN]		= { .type = NLA_U32 },
	[NDTPA_QUEUE_LENBYTES]		= { .type = NLA_U32 },
	[NDTPA_PROXY_QLEN]		= { .type = NLA_U32 },
	[NDTPA_APP_PROBES]		= { .type = NLA_U32 },
	[NDTPA_UCAST_PROBES]		= { .type = NLA_U32 },
	[NDTPA_MCAST_PROBES]		= { .type = NLA_U32 },
	[NDTPA_MCAST_REPROBES]		= { .type = NLA_U32 },
	[NDTPA_BASE_REACHABLE_TIME]	= { .type = NLA_U64 },
	[NDTPA_GC_STALETIME]		= { .type = NLA_U64 },
	[NDTPA_DELAY_PROBE_TIME]	= { .type = NLA_U64 },
	[NDTPA_RETRANS_TIME]		= { .type = NLA_U64 },
	[NDTPA_ANYCAST_DELAY]		= { .type = NLA_U64 },
	[NDTPA_PROXY_DELAY]		= { .type = NLA_U64 },
	[NDTPA_LOCKTIME]		= { .type = NLA_U64 },
	[NDTPA_INTERVAL_PROBE_TIME_MS]	= { .type = NLA_U64, .min = 1 },
};

static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh,
			struct netlink_ext_ack *extack)
{
	struct net *net = sock_net(skb->sk);
	struct nlattr *tb[NDTA_MAX + 1];
	struct neigh_table *tbl;
	struct ndtmsg *ndtmsg;
	bool found = false;
	int err, tidx;

	err = nlmsg_parse_deprecated(nlh, sizeof(*ndtmsg), tb, NDTA_MAX,
				     nl_neightbl_policy, extack);
	if (err < 0)
		goto errout;

	if (tb[NDTA_NAME] == NULL) {
		err = -EINVAL;
		goto errout;
	}

	ndtmsg = nlmsg_data(nlh);

	rcu_read_lock();

	for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) {
		tbl = rcu_dereference(neigh_tables[tidx]);
		if (!tbl)
			continue;

		if (ndtmsg->ndtm_family && tbl->family != ndtmsg->ndtm_family)
			continue;

		if (nla_strcmp(tb[NDTA_NAME], tbl->id) == 0) {
			found = true;
			break;
		}
	}

	if (!found) {
		rcu_read_unlock();
		err = -ENOENT;
		goto errout;
	}

	/*
	 * We acquire tbl->lock to be nice to the periodic timers and
	 * make sure they always see a consistent set of values.
	 */
	spin_lock_bh(&tbl->lock);

	if (tb[NDTA_PARMS]) {
		struct nlattr *tbp[NDTPA_MAX+1];
		struct neigh_parms *p;
		int i, ifindex = 0;

		err = nla_parse_nested_deprecated(tbp, NDTPA_MAX,
						  tb[NDTA_PARMS],
						  nl_ntbl_parm_policy, extack);
		if (err < 0)
			goto errout_tbl_lock;

		if (tbp[NDTPA_IFINDEX])
			ifindex = nla_get_u32(tbp[NDTPA_IFINDEX]);

		p = lookup_neigh_parms(tbl, net, ifindex);
		if (p == NULL) {
			err = -ENOENT;
			goto errout_tbl_lock;
		}

		for (i = 1; i <= NDTPA_MAX; i++) {
			if (tbp[i] == NULL)
				continue;

			switch (i) {
			case NDTPA_QUEUE_LEN:
				NEIGH_VAR_SET(p, QUEUE_LEN_BYTES,
					      nla_get_u32(tbp[i]) *
					      SKB_TRUESIZE(ETH_FRAME_LEN));
				break;
			case NDTPA_QUEUE_LENBYTES:
				NEIGH_VAR_SET(p, QUEUE_LEN_BYTES,
					      nla_get_u32(tbp[i]));
				break;
			case NDTPA_PROXY_QLEN:
				NEIGH_VAR_SET(p, PROXY_QLEN,
					      nla_get_u32(tbp[i]));
				break;
			case NDTPA_APP_PROBES:
				NEIGH_VAR_SET(p, APP_PROBES,
					      nla_get_u32(tbp[i]));
				break;
			case NDTPA_UCAST_PROBES:
				NEIGH_VAR_SET(p, UCAST_PROBES,
					      nla_get_u32(tbp[i]));
				break;
			case NDTPA_MCAST_PROBES:
				NEIGH_VAR_SET(p, MCAST_PROBES,
					      nla_get_u32(tbp[i]));
				break;
			case NDTPA_MCAST_REPROBES:
				NEIGH_VAR_SET(p, MCAST_REPROBES,
					      nla_get_u32(tbp[i]));
				break;
			case NDTPA_BASE_REACHABLE_TIME:
				NEIGH_VAR_SET(p, BASE_REACHABLE_TIME,
					      nla_get_msecs(tbp[i]));
				/* update reachable_time as well, otherwise, the change will
				 * only be effective after the next time neigh_periodic_work
				 * decides to recompute it (can be multiple minutes)
				 */
				neigh_set_reach_time(p);
				break;
			case NDTPA_GC_STALETIME:
				NEIGH_VAR_SET(p, GC_STALETIME,
					      nla_get_msecs(tbp[i]));
				break;
			case NDTPA_DELAY_PROBE_TIME:
				NEIGH_VAR_SET(p, DELAY_PROBE_TIME,
					      nla_get_msecs(tbp[i]));
				call_netevent_notifiers(NETEVENT_DELAY_PROBE_TIME_UPDATE, p);
				break;
			case NDTPA_INTERVAL_PROBE_TIME_MS:
				NEIGH_VAR_SET(p, INTERVAL_PROBE_TIME_MS,
					      nla_get_msecs(tbp[i]));
				break;
			case NDTPA_RETRANS_TIME:
				NEIGH_VAR_SET(p, RETRANS_TIME,
					      nla_get_msecs(tbp[i]));
				break;
			case NDTPA_ANYCAST_DELAY:
				NEIGH_VAR_SET(p, ANYCAST_DELAY,
					      nla_get_msecs(tbp[i]));
				break;
			case NDTPA_PROXY_DELAY:
				NEIGH_VAR_SET(p, PROXY_DELAY,
					      nla_get_msecs(tbp[i]));
				break;
			case NDTPA_LOCKTIME:
				NEIGH_VAR_SET(p, LOCKTIME,
					      nla_get_msecs(tbp[i]));
				break;
			}
		}
	}

	err = -ENOENT;
	if ((tb[NDTA_THRESH1] || tb[NDTA_THRESH2] ||
	     tb[NDTA_THRESH3] || tb[NDTA_GC_INTERVAL]) &&
	    !net_eq(net, &init_net))
		goto errout_tbl_lock;

	if (tb[NDTA_THRESH1])
		WRITE_ONCE(tbl->gc_thresh1, nla_get_u32(tb[NDTA_THRESH1]));

	if (tb[NDTA_THRESH2])
		WRITE_ONCE(tbl->gc_thresh2, nla_get_u32(tb[NDTA_THRESH2]));

	if (tb[NDTA_THRESH3])
		WRITE_ONCE(tbl->gc_thresh3, nla_get_u32(tb[NDTA_THRESH3]));

	if (tb[NDTA_GC_INTERVAL])
		WRITE_ONCE(tbl->gc_interval, nla_get_msecs(tb[NDTA_GC_INTERVAL]));

	err = 0;

errout_tbl_lock:
	spin_unlock_bh(&tbl->lock);
	rcu_read_unlock();
errout:
	return err;
}

static int neightbl_valid_dump_info(const struct nlmsghdr *nlh,
				    struct netlink_ext_ack *extack)
{
	struct ndtmsg *ndtm;

	ndtm = nlmsg_payload(nlh, sizeof(*ndtm));
	if (!ndtm) {
		NL_SET_ERR_MSG(extack, "Invalid header for neighbor table dump request");
		return -EINVAL;
	}

	if (ndtm->ndtm_pad1  || ndtm->ndtm_pad2) {
		NL_SET_ERR_MSG(extack, "Invalid values in header for neighbor table dump request");
		return -EINVAL;
	}

	if (nlmsg_attrlen(nlh, sizeof(*ndtm))) {
		NL_SET_ERR_MSG(extack, "Invalid data after header in neighbor table dump request");
		return -EINVAL;
	}

	return 0;
}

static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
{
	const struct nlmsghdr *nlh = cb->nlh;
	struct net *net = sock_net(skb->sk);
	int family, tidx, nidx = 0;
	int tbl_skip = cb->args[0];
	int neigh_skip = cb->args[1];
	struct neigh_table *tbl;

	if (cb->strict_check) {
		int err = neightbl_valid_dump_info(nlh, cb->extack);

		if (err < 0)
			return err;
	}

	family = ((struct rtgenmsg *)nlmsg_data(nlh))->rtgen_family;

	rcu_read_lock();

	for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) {
		struct neigh_parms *p;

		tbl = rcu_dereference(neigh_tables[tidx]);
		if (!tbl)
			continue;

		if (tidx < tbl_skip || (family && tbl->family != family))
			continue;

		if (neightbl_fill_info(skb, tbl, NETLINK_CB(cb->skb).portid,
				       nlh->nlmsg_seq, RTM_NEWNEIGHTBL,
				       NLM_F_MULTI) < 0)
			break;

		nidx = 0;
		p = list_next_entry(&tbl->parms, list);
		list_for_each_entry_from_rcu(p, &tbl->parms_list, list) {
			if (!net_eq(neigh_parms_net(p), net))
				continue;

			if (nidx < neigh_skip)
				goto next;

			if (neightbl_fill_param_info(skb, tbl, p,
						     NETLINK_CB(cb->skb).portid,
						     nlh->nlmsg_seq,
						     RTM_NEWNEIGHTBL,
						     NLM_F_MULTI) < 0)
				goto out;
		next:
			nidx++;
		}

		neigh_skip = 0;
	}
out:
	rcu_read_unlock();

	cb->args[0] = tidx;
	cb->args[1] = nidx;

	return skb->len;
}

static int __neigh_fill_info(struct sk_buff *skb, struct neighbour *neigh,
			     u32 pid, u32 seq, int type, unsigned int flags)
{
	u32 neigh_flags, neigh_flags_ext;
	unsigned long now = jiffies;
	struct nda_cacheinfo ci;
	struct nlmsghdr *nlh;
	struct ndmsg *ndm;

	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ndm), flags);
	if (nlh == NULL)
		return -EMSGSIZE;

	neigh_flags_ext = neigh->flags >> NTF_EXT_SHIFT;
	neigh_flags     = neigh->flags & NTF_OLD_MASK;

	ndm = nlmsg_data(nlh);
	ndm->ndm_family	 = neigh->ops->family;
	ndm->ndm_pad1    = 0;
	ndm->ndm_pad2    = 0;
	ndm->ndm_flags	 = neigh_flags;
	ndm->ndm_type	 = neigh->type;
	ndm->ndm_ifindex = neigh->dev->ifindex;

	if (nla_put(skb, NDA_DST, neigh->tbl->key_len, neigh->primary_key))
		goto nla_put_failure;

	ndm->ndm_state	 = neigh->nud_state;
	if (neigh->nud_state & NUD_VALID) {
		char haddr[MAX_ADDR_LEN];

		neigh_ha_snapshot(haddr, neigh, neigh->dev);
		if (nla_put(skb, NDA_LLADDR, neigh->dev->addr_len, haddr) < 0)
			goto nla_put_failure;
	}

	ci.ndm_used	 = jiffies_to_clock_t(now - neigh->used);
	ci.ndm_confirmed = jiffies_to_clock_t(now - neigh->confirmed);
	ci.ndm_updated	 = jiffies_to_clock_t(now - neigh->updated);
	ci.ndm_refcnt	 = refcount_read(&neigh->refcnt) - 1;

	if (nla_put_u32(skb, NDA_PROBES, atomic_read(&neigh->probes)) ||
	    nla_put(skb, NDA_CACHEINFO, sizeof(ci), &ci))
		goto nla_put_failure;

	if (neigh->protocol && nla_put_u8(skb, NDA_PROTOCOL, neigh->protocol))
		goto nla_put_failure;
	if (neigh_flags_ext && nla_put_u32(skb, NDA_FLAGS_EXT, neigh_flags_ext))
		goto nla_put_failure;

	nlmsg_end(skb, nlh);
	return 0;

nla_put_failure:
	nlmsg_cancel(skb, nlh);
	return -EMSGSIZE;
}

static int neigh_fill_info(struct sk_buff *skb, struct neighbour *neigh,
			   u32 pid, u32 seq, int type, unsigned int flags)
	__releases(neigh->lock)
	__acquires(neigh->lock)
{
	int err;

	read_lock_bh(&neigh->lock);
	err = __neigh_fill_info(skb, neigh, pid, seq, type, flags);
	read_unlock_bh(&neigh->lock);

	return err;
}

static int pneigh_fill_info(struct sk_buff *skb, struct pneigh_entry *pn,
			    u32 pid, u32 seq, int type, unsigned int flags,
			    struct neigh_table *tbl)
{
	u32 neigh_flags, neigh_flags_ext;
	struct nlmsghdr *nlh;
	struct ndmsg *ndm;
	u8 protocol;

	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ndm), flags);
	if (nlh == NULL)
		return -EMSGSIZE;

	neigh_flags = READ_ONCE(pn->flags);
	neigh_flags_ext = neigh_flags >> NTF_EXT_SHIFT;
	neigh_flags &= NTF_OLD_MASK;

	ndm = nlmsg_data(nlh);
	ndm->ndm_family	 = tbl->family;
	ndm->ndm_pad1    = 0;
	ndm->ndm_pad2    = 0;
	ndm->ndm_flags	 = neigh_flags | NTF_PROXY;
	ndm->ndm_type	 = RTN_UNICAST;
	ndm->ndm_ifindex = pn->dev ? pn->dev->ifindex : 0;
	ndm->ndm_state	 = NUD_NONE;

	if (nla_put(skb, NDA_DST, tbl->key_len, pn->key))
		goto nla_put_failure;

	protocol = READ_ONCE(pn->protocol);
	if (protocol && nla_put_u8(skb, NDA_PROTOCOL, protocol))
		goto nla_put_failure;
	if (neigh_flags_ext && nla_put_u32(skb, NDA_FLAGS_EXT, neigh_flags_ext))
		goto nla_put_failure;

	nlmsg_end(skb, nlh);
	return 0;

nla_put_failure:
	nlmsg_cancel(skb, nlh);
	return -EMSGSIZE;
}

static bool neigh_master_filtered(struct net_device *dev, int master_idx)
{
	struct net_device *master;

	if (!master_idx)
		return false;

	master = dev ? netdev_master_upper_dev_get_rcu(dev) : NULL;

	/* 0 is already used to denote NDA_MASTER wasn't passed, therefore need another
	 * invalid value for ifindex to denote "no master".
	 */
	if (master_idx == -1)
		return !!master;

	if (!master || master->ifindex != master_idx)
		return true;

	return false;
}

static bool neigh_ifindex_filtered(struct net_device *dev, int filter_idx)
{
	if (filter_idx && (!dev || dev->ifindex != filter_idx))
		return true;

	return false;
}

struct neigh_dump_filter {
	int master_idx;
	int dev_idx;
};

static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
			    struct netlink_callback *cb,
			    struct neigh_dump_filter *filter)
{
	struct net *net = sock_net(skb->sk);
	struct neighbour *n;
	int err = 0, h, s_h = cb->args[1];
	int idx, s_idx = idx = cb->args[2];
	struct neigh_hash_table *nht;
	unsigned int flags = NLM_F_MULTI;

	if (filter->dev_idx || filter->master_idx)
		flags |= NLM_F_DUMP_FILTERED;

	nht = rcu_dereference(tbl->nht);

	for (h = s_h; h < (1 << nht->hash_shift); h++) {
		if (h > s_h)
			s_idx = 0;
		idx = 0;
		neigh_for_each_in_bucket_rcu(n, &nht->hash_heads[h]) {
			if (idx < s_idx || !net_eq(dev_net(n->dev), net))
				goto next;
			if (neigh_ifindex_filtered(n->dev, filter->dev_idx) ||
			    neigh_master_filtered(n->dev, filter->master_idx))
				goto next;
			err = neigh_fill_info(skb, n, NETLINK_CB(cb->skb).portid,
					      cb->nlh->nlmsg_seq,
					      RTM_NEWNEIGH, flags);
			if (err < 0)
				goto out;
next:
			idx++;
		}
	}
out:
	cb->args[1] = h;
	cb->args[2] = idx;
	return err;
}

static int pneigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
			     struct netlink_callback *cb,
			     struct neigh_dump_filter *filter)
{
	struct pneigh_entry *n;
	struct net *net = sock_net(skb->sk);
	int err = 0, h, s_h = cb->args[3];
	int idx, s_idx = idx = cb->args[4];
	unsigned int flags = NLM_F_MULTI;

	if (filter->dev_idx || filter->master_idx)
		flags |= NLM_F_DUMP_FILTERED;

	for (h = s_h; h <= PNEIGH_HASHMASK; h++) {
		if (h > s_h)
			s_idx = 0;
		for (n = rcu_dereference(tbl->phash_buckets[h]), idx = 0;
		     n;
		     n = rcu_dereference(n->next)) {
			if (idx < s_idx || pneigh_net(n) != net)
				goto next;
			if (neigh_ifindex_filtered(n->dev, filter->dev_idx) ||
			    neigh_master_filtered(n->dev, filter->master_idx))
				goto next;
			err = pneigh_fill_info(skb, n, NETLINK_CB(cb->skb).portid,
					       cb->nlh->nlmsg_seq,
					       RTM_NEWNEIGH, flags, tbl);
			if (err < 0)
				goto out;
		next:
			idx++;
		}
	}

out:
	cb->args[3] = h;
	cb->args[4] = idx;
	return err;
}

static int neigh_valid_dump_req(const struct nlmsghdr *nlh,
				bool strict_check,
				struct neigh_dump_filter *filter,
				struct netlink_ext_ack *extack)
{
	struct nlattr *tb[NDA_MAX + 1];
	int err, i;

	if (strict_check) {
		struct ndmsg *ndm;

		ndm = nlmsg_payload(nlh, sizeof(*ndm));
		if (!ndm) {
			NL_SET_ERR_MSG(extack, "Invalid header for neighbor dump request");
			return -EINVAL;
		}

		if (ndm->ndm_pad1  || ndm->ndm_pad2  || ndm->ndm_ifindex ||
		    ndm->ndm_state || ndm->ndm_type) {
			NL_SET_ERR_MSG(extack, "Invalid values in header for neighbor dump request");
			return -EINVAL;
		}

		if (ndm->ndm_flags & ~NTF_PROXY) {
			NL_SET_ERR_MSG(extack, "Invalid flags in header for neighbor dump request");
			return -EINVAL;
		}

		err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct ndmsg),
						    tb, NDA_MAX, nda_policy,
						    extack);
	} else {
		err = nlmsg_parse_deprecated(nlh, sizeof(struct ndmsg), tb,
					     NDA_MAX, nda_policy, extack);
	}
	if (err < 0)
		return err;

	for (i = 0; i <= NDA_MAX; ++i) {
		if (!tb[i])
			continue;

		/* all new attributes should require strict_check */
		switch (i) {
		case NDA_IFINDEX:
			filter->dev_idx = nla_get_u32(tb[i]);
			break;
		case NDA_MASTER:
			filter->master_idx = nla_get_u32(tb[i]);
			break;
		default:
			if (strict_check) {
				NL_SET_ERR_MSG(extack, "Unsupported attribute in neighbor dump request");
				return -EINVAL;
			}
		}
	}

	return 0;
}

static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
{
	const struct nlmsghdr *nlh = cb->nlh;
	struct neigh_dump_filter filter = {};
	struct neigh_table *tbl;
	int t, family, s_t;
	int proxy = 0;
	int err;

	family = ((struct rtgenmsg *)nlmsg_data(nlh))->rtgen_family;

	/* check for full ndmsg structure presence, family member is
	 * the same for both structures
	 */
	if (nlmsg_len(nlh) >= sizeof(struct ndmsg) &&
	    ((struct ndmsg *)nlmsg_data(nlh))->ndm_flags == NTF_PROXY)
		proxy = 1;

	err = neigh_valid_dump_req(nlh, cb->strict_check, &filter, cb->extack);
	if (err < 0 && cb->strict_check)
		return err;
	err = 0;

	s_t = cb->args[0];

	rcu_read_lock();
	for (t = 0; t < NEIGH_NR_TABLES; t++) {
		tbl = rcu_dereference(neigh_tables[t]);

		if (!tbl)
			continue;
		if (t < s_t || (family && tbl->family != family))
			continue;
		if (t > s_t)
			memset(&cb->args[1], 0, sizeof(cb->args) -
						sizeof(cb->args[0]));
		if (proxy)
			err = pneigh_dump_table(tbl, skb, cb, &filter);
		else
			err = neigh_dump_table(tbl, skb, cb, &filter);
		if (err < 0)
			break;
	}
	rcu_read_unlock();

	cb->args[0] = t;
	return err;
}

static struct ndmsg *neigh_valid_get_req(const struct nlmsghdr *nlh,
					 struct nlattr **tb,
					 struct netlink_ext_ack *extack)
{
	struct ndmsg *ndm;
	int err, i;

	ndm = nlmsg_payload(nlh, sizeof(*ndm));
	if (!ndm) {
		NL_SET_ERR_MSG(extack, "Invalid header for neighbor get request");
		return ERR_PTR(-EINVAL);
	}

	if (ndm->ndm_pad1  || ndm->ndm_pad2  || ndm->ndm_state ||
	    ndm->ndm_type) {
		NL_SET_ERR_MSG(extack, "Invalid values in header for neighbor get request");
		return ERR_PTR(-EINVAL);
	}

	if (ndm->ndm_flags & ~NTF_PROXY) {
		NL_SET_ERR_MSG(extack, "Invalid flags in header for neighbor get request");
		return ERR_PTR(-EINVAL);
	}

	if (!(ndm->ndm_flags & NTF_PROXY) && !ndm->ndm_ifindex) {
		NL_SET_ERR_MSG(extack, "No device specified");
		return ERR_PTR(-EINVAL);
	}

	err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct ndmsg), tb,
					    NDA_MAX, nda_policy, extack);
	if (err < 0)
		return ERR_PTR(err);

	for (i = 0; i <= NDA_MAX; ++i) {
		switch (i) {
		case NDA_DST:
			if (!tb[i]) {
				NL_SET_ERR_ATTR_MISS(extack, NULL, NDA_DST);
				return ERR_PTR(-EINVAL);
			}
			break;
		default:
			if (!tb[i])
				continue;

			NL_SET_ERR_MSG(extack, "Unsupported attribute in neighbor get request");
			return ERR_PTR(-EINVAL);
		}
	}

	return ndm;
}

static inline size_t neigh_nlmsg_size(void)
{
	return NLMSG_ALIGN(sizeof(struct ndmsg))
	       + nla_total_size(MAX_ADDR_LEN) /* NDA_DST */
	       + nla_total_size(MAX_ADDR_LEN) /* NDA_LLADDR */
	       + nla_total_size(sizeof(struct nda_cacheinfo))
	       + nla_total_size(4)  /* NDA_PROBES */
	       + nla_total_size(4)  /* NDA_FLAGS_EXT */
	       + nla_total_size(1); /* NDA_PROTOCOL */
}

static inline size_t pneigh_nlmsg_size(void)
{
	return NLMSG_ALIGN(sizeof(struct ndmsg))
	       + nla_total_size(MAX_ADDR_LEN) /* NDA_DST */
	       + nla_total_size(4)  /* NDA_FLAGS_EXT */
	       + nla_total_size(1); /* NDA_PROTOCOL */
}

static int neigh_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
		     struct netlink_ext_ack *extack)
{
	struct net *net = sock_net(in_skb->sk);
	u32 pid = NETLINK_CB(in_skb).portid;
	struct nlattr *tb[NDA_MAX + 1];
	struct net_device *dev = NULL;
	u32 seq = nlh->nlmsg_seq;
	struct neigh_table *tbl;
	struct neighbour *neigh;
	struct sk_buff *skb;
	struct ndmsg *ndm;
	void *dst;
	int err;

	ndm = neigh_valid_get_req(nlh, tb, extack);
	if (IS_ERR(ndm))
		return PTR_ERR(ndm);

	if (ndm->ndm_flags & NTF_PROXY)
		skb = nlmsg_new(neigh_nlmsg_size(), GFP_KERNEL);
	else
		skb = nlmsg_new(pneigh_nlmsg_size(), GFP_KERNEL);
	if (!skb)
		return -ENOBUFS;

	rcu_read_lock();

	tbl = neigh_find_table(ndm->ndm_family);
	if (!tbl) {
		NL_SET_ERR_MSG(extack, "Unsupported family in header for neighbor get request");
		err = -EAFNOSUPPORT;
		goto err_unlock;
	}

	if (nla_len(tb[NDA_DST]) != (int)tbl->key_len) {
		NL_SET_ERR_MSG(extack, "Invalid network address in neighbor get request");
		err = -EINVAL;
		goto err_unlock;
	}

	dst = nla_data(tb[NDA_DST]);

	if (ndm->ndm_ifindex) {
		dev = dev_get_by_index_rcu(net, ndm->ndm_ifindex);
		if (!dev) {
			NL_SET_ERR_MSG(extack, "Unknown device ifindex");
			err = -ENODEV;
			goto err_unlock;
		}
	}

	if (ndm->ndm_flags & NTF_PROXY) {
		struct pneigh_entry *pn;

		pn = pneigh_lookup(tbl, net, dst, dev);
		if (!pn) {
			NL_SET_ERR_MSG(extack, "Proxy neighbour entry not found");
			err = -ENOENT;
			goto err_unlock;
		}

		err = pneigh_fill_info(skb, pn, pid, seq, RTM_NEWNEIGH, 0, tbl);
		if (err)
			goto err_unlock;
	} else {
		neigh = neigh_lookup(tbl, dst, dev);
		if (!neigh) {
			NL_SET_ERR_MSG(extack, "Neighbour entry not found");
			err = -ENOENT;
			goto err_unlock;
		}

		err = neigh_fill_info(skb, neigh, pid, seq, RTM_NEWNEIGH, 0);
		neigh_release(neigh);
		if (err)
			goto err_unlock;
	}

	rcu_read_unlock();

	return rtnl_unicast(skb, net, pid);
err_unlock:
	rcu_read_unlock();
	kfree_skb(skb);
	return err;
}

void neigh_for_each(struct neigh_table *tbl, void (*cb)(struct neighbour *, void *), void *cookie)
{
	int chain;
	struct neigh_hash_table *nht;

	rcu_read_lock();
	nht = rcu_dereference(tbl->nht);

	spin_lock_bh(&tbl->lock); /* avoid resizes */
	for (chain = 0; chain < (1 << nht->hash_shift); chain++) {
		struct neighbour *n;

		neigh_for_each_in_bucket(n, &nht->hash_heads[chain])
			cb(n, cookie);
	}
	spin_unlock_bh(&tbl->lock);
	rcu_read_unlock();
}
EXPORT_SYMBOL(neigh_for_each);

/* The tbl->lock must be held as a writer and BH disabled. */
void __neigh_for_each_release(struct neigh_table *tbl,
			      int (*cb)(struct neighbour *))
{
	struct neigh_hash_table *nht;
	int chain;

	nht = rcu_dereference_protected(tbl->nht,
					lockdep_is_held(&tbl->lock));
	for (chain = 0; chain < (1 << nht->hash_shift); chain++) {
		struct hlist_node *tmp;
		struct neighbour *n;

		neigh_for_each_in_bucket_safe(n, tmp, &nht->hash_heads[chain]) {
			int release;

			write_lock(&n->lock);
			release = cb(n);
			if (release) {
				hlist_del_rcu(&n->hash);
				hlist_del_rcu(&n->dev_list);
				neigh_mark_dead(n);
			}
			write_unlock(&n->lock);
			if (release)
				neigh_cleanup_and_release(n);
		}
	}
}
EXPORT_SYMBOL(__neigh_for_each_release);

int neigh_xmit(int index, struct net_device *dev,
	       const void *addr, struct sk_buff *skb)
{
	int err = -EAFNOSUPPORT;

	if (likely(index < NEIGH_NR_TABLES)) {
		struct neigh_table *tbl;
		struct neighbour *neigh;

		rcu_read_lock();
		tbl = rcu_dereference(neigh_tables[index]);
		if (!tbl)
			goto out_unlock;
		if (index == NEIGH_ARP_TABLE) {
			u32 key = *((u32 *)addr);

			neigh = __ipv4_neigh_lookup_noref(dev, key);
		} else {
			neigh = __neigh_lookup_noref(tbl, addr, dev);
		}
		if (!neigh)
			neigh = __neigh_create(tbl, addr, dev, false);
		err = PTR_ERR(neigh);
		if (IS_ERR(neigh)) {
			rcu_read_unlock();
			goto out_kfree_skb;
		}
		err = READ_ONCE(neigh->output)(neigh, skb);
out_unlock:
		rcu_read_unlock();
	}
	else if (index == NEIGH_LINK_TABLE) {
		err = dev_hard_header(skb, dev, ntohs(skb->protocol),
				      addr, NULL, skb->len);
		if (err < 0)
			goto out_kfree_skb;
		err = dev_queue_xmit(skb);
	}
out:
	return err;
out_kfree_skb:
	kfree_skb(skb);
	goto out;
}
EXPORT_SYMBOL(neigh_xmit);

#ifdef CONFIG_PROC_FS

static struct neighbour *neigh_get_valid(struct seq_file *seq,
					 struct neighbour *n,
					 loff_t *pos)
{
	struct neigh_seq_state *state = seq->private;
	struct net *net = seq_file_net(seq);

	if (!net_eq(dev_net(n->dev), net))
		return NULL;

	if (state->neigh_sub_iter) {
		loff_t fakep = 0;
		void *v;

		v = state->neigh_sub_iter(state, n, pos ? pos : &fakep);
		if (!v)
			return NULL;
		if (pos)
			return v;
	}

	if (!(state->flags & NEIGH_SEQ_SKIP_NOARP))
		return n;

	if (READ_ONCE(n->nud_state) & ~NUD_NOARP)
		return n;

	return NULL;
}

static struct neighbour *neigh_get_first(struct seq_file *seq)
{
	struct neigh_seq_state *state = seq->private;
	struct neigh_hash_table *nht = state->nht;
	struct neighbour *n, *tmp;

	state->flags &= ~NEIGH_SEQ_IS_PNEIGH;

	while (++state->bucket < (1 << nht->hash_shift)) {
		neigh_for_each_in_bucket(n, &nht->hash_heads[state->bucket]) {
			tmp = neigh_get_valid(seq, n, NULL);
			if (tmp)
				return tmp;
		}
	}

	return NULL;
}

static struct neighbour *neigh_get_next(struct seq_file *seq,
					struct neighbour *n,
					loff_t *pos)
{
	struct neigh_seq_state *state = seq->private;
	struct neighbour *tmp;

	if (state->neigh_sub_iter) {
		void *v = state->neigh_sub_iter(state, n, pos);

		if (v)
			return n;
	}

	hlist_for_each_entry_continue(n, hash) {
		tmp = neigh_get_valid(seq, n, pos);
		if (tmp) {
			n = tmp;
			goto out;
		}
	}

	n = neigh_get_first(seq);
out:
	if (n && pos)
		--(*pos);

	return n;
}

static struct neighbour *neigh_get_idx(struct seq_file *seq, loff_t *pos)
{
	struct neighbour *n = neigh_get_first(seq);

	if (n) {
		--(*pos);
		while (*pos) {
			n = neigh_get_next(seq, n, pos);
			if (!n)
				break;
		}
	}
	return *pos ? NULL : n;
}

static struct pneigh_entry *pneigh_get_first(struct seq_file *seq)
{
	struct neigh_seq_state *state = seq->private;
	struct net *net = seq_file_net(seq);
	struct neigh_table *tbl = state->tbl;
	struct pneigh_entry *pn = NULL;
	int bucket;

	state->flags |= NEIGH_SEQ_IS_PNEIGH;
	for (bucket = 0; bucket <= PNEIGH_HASHMASK; bucket++) {
		pn = rcu_dereference(tbl->phash_buckets[bucket]);

		while (pn && !net_eq(pneigh_net(pn), net))
			pn = rcu_dereference(pn->next);
		if (pn)
			break;
	}
	state->bucket = bucket;

	return pn;
}

static struct pneigh_entry *pneigh_get_next(struct seq_file *seq,
					    struct pneigh_entry *pn,
					    loff_t *pos)
{
	struct neigh_seq_state *state = seq->private;
	struct net *net = seq_file_net(seq);
	struct neigh_table *tbl = state->tbl;

	do {
		pn = rcu_dereference(pn->next);
	} while (pn && !net_eq(pneigh_net(pn), net));

	while (!pn) {
		if (++state->bucket > PNEIGH_HASHMASK)
			break;

		pn = rcu_dereference(tbl->phash_buckets[state->bucket]);

		while (pn && !net_eq(pneigh_net(pn), net))
			pn = rcu_dereference(pn->next);
		if (pn)
			break;
	}

	if (pn && pos)
		--(*pos);

	return pn;
}

static struct pneigh_entry *pneigh_get_idx(struct seq_file *seq, loff_t *pos)
{
	struct pneigh_entry *pn = pneigh_get_first(seq);

	if (pn) {
		--(*pos);
		while (*pos) {
			pn = pneigh_get_next(seq, pn, pos);
			if (!pn)
				break;
		}
	}
	return *pos ? NULL : pn;
}

static void *neigh_get_idx_any(struct seq_file *seq, loff_t *pos)
{
	struct neigh_seq_state *state = seq->private;
	void *rc;
	loff_t idxpos = *pos;

	rc = neigh_get_idx(seq, &idxpos);
	if (!rc && !(state->flags & NEIGH_SEQ_NEIGH_ONLY))
		rc = pneigh_get_idx(seq, &idxpos);

	return rc;
}

void *neigh_seq_start(struct seq_file *seq, loff_t *pos, struct neigh_table *tbl, unsigned int neigh_seq_flags)
	__acquires(tbl->lock)
	__acquires(rcu)
{
	struct neigh_seq_state *state = seq->private;

	state->tbl = tbl;
	state->bucket = -1;
	state->flags = (neigh_seq_flags & ~NEIGH_SEQ_IS_PNEIGH);

	rcu_read_lock();
	state->nht = rcu_dereference(tbl->nht);
	spin_lock_bh(&tbl->lock);

	return *pos ? neigh_get_idx_any(seq, pos) : SEQ_START_TOKEN;
}
EXPORT_SYMBOL(neigh_seq_start);

void *neigh_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct neigh_seq_state *state;
	void *rc;

	if (v == SEQ_START_TOKEN) {
		rc = neigh_get_first(seq);
		goto out;
	}

	state = seq->private;
	if (!(state->flags & NEIGH_SEQ_IS_PNEIGH)) {
		rc = neigh_get_next(seq, v, NULL);
		if (rc)
			goto out;
		if (!(state->flags & NEIGH_SEQ_NEIGH_ONLY))
			rc = pneigh_get_first(seq);
	} else {
		BUG_ON(state->flags & NEIGH_SEQ_NEIGH_ONLY);
		rc = pneigh_get_next(seq, v, NULL);
	}
out:
	++(*pos);
	return rc;
}
EXPORT_SYMBOL(neigh_seq_next);

void neigh_seq_stop(struct seq_file *seq, void *v)
	__releases(tbl->lock)
	__releases(rcu)
{
	struct neigh_seq_state *state = seq->private;
	struct neigh_table *tbl = state->tbl;

	spin_unlock_bh(&tbl->lock);
	rcu_read_unlock();
}
EXPORT_SYMBOL(neigh_seq_stop);

/* statistics via seq_file */

static void *neigh_stat_seq_start(struct seq_file *seq, loff_t *pos)
{
	struct neigh_table *tbl = pde_data(file_inode(seq->file));
	int cpu;

	if (*pos == 0)
		return SEQ_START_TOKEN;

	for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
		if (!cpu_possible(cpu))
			continue;
		*pos = cpu+1;
		return per_cpu_ptr(tbl->stats, cpu);
	}
	return NULL;
}

static void *neigh_stat_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct neigh_table *tbl = pde_data(file_inode(seq->file));
	int cpu;

	for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
		if (!cpu_possible(cpu))
			continue;
		*pos = cpu+1;
		return per_cpu_ptr(tbl->stats, cpu);
	}
	(*pos)++;
	return NULL;
}

static void neigh_stat_seq_stop(struct seq_file *seq, void *v)
{

}

static int neigh_stat_seq_show(struct seq_file *seq, void *v)
{
	struct neigh_table *tbl = pde_data(file_inode(seq->file));
	struct neigh_statistics *st = v;

	if (v == SEQ_START_TOKEN) {
		seq_puts(seq, "entries  allocs   destroys hash_grows lookups  hits     res_failed rcv_probes_mcast rcv_probes_ucast periodic_gc_runs forced_gc_runs unresolved_discards table_fulls\n");
		return 0;
	}

	seq_printf(seq, "%08x %08lx %08lx %08lx   %08lx %08lx %08lx   "
			"%08lx         %08lx         %08lx         "
			"%08lx       %08lx            %08lx\n",
		   atomic_read(&tbl->entries),

		   st->allocs,
		   st->destroys,
		   st->hash_grows,

		   st->lookups,
		   st->hits,

		   st->res_failed,

		   st->rcv_probes_mcast,
		   st->rcv_probes_ucast,

		   st->periodic_gc_runs,
		   st->forced_gc_runs,
		   st->unres_discards,
		   st->table_fulls
		   );

	return 0;
}

static const struct seq_operations neigh_stat_seq_ops = {
	.start	= neigh_stat_seq_start,
	.next	= neigh_stat_seq_next,
	.stop	= neigh_stat_seq_stop,
	.show	= neigh_stat_seq_show,
};
#endif /* CONFIG_PROC_FS */

static void __neigh_notify(struct neighbour *n, int type, int flags,
			   u32 pid)
{
	struct sk_buff *skb;
	int err = -ENOBUFS;
	struct net *net;

	rcu_read_lock();
	net = dev_net_rcu(n->dev);
	skb = nlmsg_new(neigh_nlmsg_size(), GFP_ATOMIC);
	if (skb == NULL)
		goto errout;

	err = __neigh_fill_info(skb, n, pid, 0, type, flags);
	if (err < 0) {
		/* -EMSGSIZE implies BUG in neigh_nlmsg_size() */
		WARN_ON(err == -EMSGSIZE);
		kfree_skb(skb);
		goto errout;
	}
	rtnl_notify(skb, net, 0, RTNLGRP_NEIGH, NULL, GFP_ATOMIC);
	goto out;
errout:
	rtnl_set_sk_err(net, RTNLGRP_NEIGH, err);
out:
	rcu_read_unlock();
}

static void neigh_notify(struct neighbour *neigh, int type, int flags, u32 pid)
{
	read_lock_bh(&neigh->lock);
	__neigh_notify(neigh, type, flags, pid);
	read_unlock_bh(&neigh->lock);
}

void neigh_app_ns(struct neighbour *n)
{
	neigh_notify(n, RTM_GETNEIGH, NLM_F_REQUEST, 0);
}
EXPORT_SYMBOL(neigh_app_ns);

#ifdef CONFIG_SYSCTL
static int unres_qlen_max = INT_MAX / SKB_TRUESIZE(ETH_FRAME_LEN);

static int proc_unres_qlen(const struct ctl_table *ctl, int write,
			   void *buffer, size_t *lenp, loff_t *ppos)
{
	int size, ret;
	struct ctl_table tmp = *ctl;

	tmp.extra1 = SYSCTL_ZERO;
	tmp.extra2 = &unres_qlen_max;
	tmp.data = &size;

	size = *(int *)ctl->data / SKB_TRUESIZE(ETH_FRAME_LEN);
	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);

	if (write && !ret)
		*(int *)ctl->data = size * SKB_TRUESIZE(ETH_FRAME_LEN);
	return ret;
}

static void neigh_copy_dflt_parms(struct net *net, struct neigh_parms *p,
				  int index)
{
	struct net_device *dev;
	int family = neigh_parms_family(p);

	rcu_read_lock();
	for_each_netdev_rcu(net, dev) {
		struct neigh_parms *dst_p =
				neigh_get_dev_parms_rcu(dev, family);

		if (dst_p && !test_bit(index, dst_p->data_state))
			dst_p->data[index] = p->data[index];
	}
	rcu_read_unlock();
}

static void neigh_proc_update(const struct ctl_table *ctl, int write)
{
	struct net_device *dev = ctl->extra1;
	struct neigh_parms *p = ctl->extra2;
	struct net *net = neigh_parms_net(p);
	int index = (int *) ctl->data - p->data;

	if (!write)
		return;

	set_bit(index, p->data_state);
	if (index == NEIGH_VAR_DELAY_PROBE_TIME)
		call_netevent_notifiers(NETEVENT_DELAY_PROBE_TIME_UPDATE, p);
	if (!dev) /* NULL dev means this is default value */
		neigh_copy_dflt_parms(net, p, index);
}

static int neigh_proc_dointvec_zero_intmax(const struct ctl_table *ctl, int write,
					   void *buffer, size_t *lenp,
					   loff_t *ppos)
{
	struct ctl_table tmp = *ctl;
	int ret;

	tmp.extra1 = SYSCTL_ZERO;
	tmp.extra2 = SYSCTL_INT_MAX;

	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
	neigh_proc_update(ctl, write);
	return ret;
}

static int neigh_proc_dointvec_ms_jiffies_positive(const struct ctl_table *ctl, int write,
						   void *buffer, size_t *lenp, loff_t *ppos)
{
	struct ctl_table tmp = *ctl;
	int ret;

	int min = msecs_to_jiffies(1);

	tmp.extra1 = &min;
	tmp.extra2 = NULL;

	ret = proc_dointvec_ms_jiffies_minmax(&tmp, write, buffer, lenp, ppos);
	neigh_proc_update(ctl, write);
	return ret;
}

int neigh_proc_dointvec(const struct ctl_table *ctl, int write, void *buffer,
			size_t *lenp, loff_t *ppos)
{
	int ret = proc_dointvec(ctl, write, buffer, lenp, ppos);

	neigh_proc_update(ctl, write);
	return ret;
}
EXPORT_SYMBOL(neigh_proc_dointvec);

int neigh_proc_dointvec_jiffies(const struct ctl_table *ctl, int write, void *buffer,
				size_t *lenp, loff_t *ppos)
{
	int ret = proc_dointvec_jiffies(ctl, write, buffer, lenp, ppos);

	neigh_proc_update(ctl, write);
	return ret;
}
EXPORT_SYMBOL(neigh_proc_dointvec_jiffies);

static int neigh_proc_dointvec_userhz_jiffies(const struct ctl_table *ctl, int write,
					      void *buffer, size_t *lenp,
					      loff_t *ppos)
{
	int ret = proc_dointvec_userhz_jiffies(ctl, write, buffer, lenp, ppos);

	neigh_proc_update(ctl, write);
	return ret;
}

int neigh_proc_dointvec_ms_jiffies(const struct ctl_table *ctl, int write,
				   void *buffer, size_t *lenp, loff_t *ppos)
{
	int ret = proc_dointvec_ms_jiffies(ctl, write, buffer, lenp, ppos);

	neigh_proc_update(ctl, write);
	return ret;
}
EXPORT_SYMBOL(neigh_proc_dointvec_ms_jiffies);

static int neigh_proc_dointvec_unres_qlen(const struct ctl_table *ctl, int write,
					  void *buffer, size_t *lenp,
					  loff_t *ppos)
{
	int ret = proc_unres_qlen(ctl, write, buffer, lenp, ppos);

	neigh_proc_update(ctl, write);
	return ret;
}

static int neigh_proc_base_reachable_time(const struct ctl_table *ctl, int write,
					  void *buffer, size_t *lenp,
					  loff_t *ppos)
{
	struct neigh_parms *p = ctl->extra2;
	int ret;

	if (strcmp(ctl->procname, "base_reachable_time") == 0)
		ret = neigh_proc_dointvec_jiffies(ctl, write, buffer, lenp, ppos);
	else if (strcmp(ctl->procname, "base_reachable_time_ms") == 0)
		ret = neigh_proc_dointvec_ms_jiffies(ctl, write, buffer, lenp, ppos);
	else
		ret = -1;

	if (write && ret == 0) {
		/* update reachable_time as well, otherwise, the change will
		 * only be effective after the next time neigh_periodic_work
		 * decides to recompute it
		 */
		neigh_set_reach_time(p);
	}
	return ret;
}

#define NEIGH_PARMS_DATA_OFFSET(index)	\
	(&((struct neigh_parms *) 0)->data[index])

#define NEIGH_SYSCTL_ENTRY(attr, data_attr, name, mval, proc) \
	[NEIGH_VAR_ ## attr] = { \
		.procname	= name, \
		.data		= NEIGH_PARMS_DATA_OFFSET(NEIGH_VAR_ ## data_attr), \
		.maxlen		= sizeof(int), \
		.mode		= mval, \
		.proc_handler	= proc, \
	}

#define NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(attr, name) \
	NEIGH_SYSCTL_ENTRY(attr, attr, name, 0644, neigh_proc_dointvec_zero_intmax)

#define NEIGH_SYSCTL_JIFFIES_ENTRY(attr, name) \
	NEIGH_SYSCTL_ENTRY(attr, attr, name, 0644, neigh_proc_dointvec_jiffies)

#define NEIGH_SYSCTL_USERHZ_JIFFIES_ENTRY(attr, name) \
	NEIGH_SYSCTL_ENTRY(attr, attr, name, 0644, neigh_proc_dointvec_userhz_jiffies)

#define NEIGH_SYSCTL_MS_JIFFIES_POSITIVE_ENTRY(attr, name) \
	NEIGH_SYSCTL_ENTRY(attr, attr, name, 0644, neigh_proc_dointvec_ms_jiffies_positive)

#define NEIGH_SYSCTL_MS_JIFFIES_REUSED_ENTRY(attr, data_attr, name) \
	NEIGH_SYSCTL_ENTRY(attr, data_attr, name, 0644, neigh_proc_dointvec_ms_jiffies)

#define NEIGH_SYSCTL_UNRES_QLEN_REUSED_ENTRY(attr, data_attr, name) \
	NEIGH_SYSCTL_ENTRY(attr, data_attr, name, 0644, neigh_proc_dointvec_unres_qlen)

static struct neigh_sysctl_table {
	struct ctl_table_header *sysctl_header;
	struct ctl_table neigh_vars[NEIGH_VAR_MAX];
} neigh_sysctl_template __read_mostly = {
	.neigh_vars = {
		NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(MCAST_PROBES, "mcast_solicit"),
		NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(UCAST_PROBES, "ucast_solicit"),
		NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(APP_PROBES, "app_solicit"),
		NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(MCAST_REPROBES, "mcast_resolicit"),
		NEIGH_SYSCTL_USERHZ_JIFFIES_ENTRY(RETRANS_TIME, "retrans_time"),
		NEIGH_SYSCTL_JIFFIES_ENTRY(BASE_REACHABLE_TIME, "base_reachable_time"),
		NEIGH_SYSCTL_JIFFIES_ENTRY(DELAY_PROBE_TIME, "delay_first_probe_time"),
		NEIGH_SYSCTL_MS_JIFFIES_POSITIVE_ENTRY(INTERVAL_PROBE_TIME_MS,
						       "interval_probe_time_ms"),
		NEIGH_SYSCTL_JIFFIES_ENTRY(GC_STALETIME, "gc_stale_time"),
		NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(QUEUE_LEN_BYTES, "unres_qlen_bytes"),
		NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(PROXY_QLEN, "proxy_qlen"),
		NEIGH_SYSCTL_USERHZ_JIFFIES_ENTRY(ANYCAST_DELAY, "anycast_delay"),
		NEIGH_SYSCTL_USERHZ_JIFFIES_ENTRY(PROXY_DELAY, "proxy_delay"),
		NEIGH_SYSCTL_USERHZ_JIFFIES_ENTRY(LOCKTIME, "locktime"),
		NEIGH_SYSCTL_UNRES_QLEN_REUSED_ENTRY(QUEUE_LEN, QUEUE_LEN_BYTES, "unres_qlen"),
		NEIGH_SYSCTL_MS_JIFFIES_REUSED_ENTRY(RETRANS_TIME_MS, RETRANS_TIME, "retrans_time_ms"),
		NEIGH_SYSCTL_MS_JIFFIES_REUSED_ENTRY(BASE_REACHABLE_TIME_MS, BASE_REACHABLE_TIME, "base_reachable_time_ms"),
		[NEIGH_VAR_GC_INTERVAL] = {
			.procname	= "gc_interval",
			.maxlen		= sizeof(int),
			.mode		= 0644,
			.proc_handler	= proc_dointvec_jiffies,
		},
		[NEIGH_VAR_GC_THRESH1] = {
			.procname	= "gc_thresh1",
			.maxlen		= sizeof(int),
			.mode		= 0644,
			.extra1		= SYSCTL_ZERO,
			.extra2		= SYSCTL_INT_MAX,
			.proc_handler	= proc_dointvec_minmax,
		},
		[NEIGH_VAR_GC_THRESH2] = {
			.procname	= "gc_thresh2",
			.maxlen		= sizeof(int),
			.mode		= 0644,
			.extra1		= SYSCTL_ZERO,
			.extra2		= SYSCTL_INT_MAX,
			.proc_handler	= proc_dointvec_minmax,
		},
		[NEIGH_VAR_GC_THRESH3] = {
			.procname	= "gc_thresh3",
			.maxlen		= sizeof(int),
			.mode		= 0644,
			.extra1		= SYSCTL_ZERO,
			.extra2		= SYSCTL_INT_MAX,
			.proc_handler	= proc_dointvec_minmax,
		},
	},
};

int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
			  proc_handler *handler)
{
	int i;
	struct neigh_sysctl_table *t;
	const char *dev_name_source;
	char neigh_path[ sizeof("net//neigh/") + IFNAMSIZ + IFNAMSIZ ];
	char *p_name;
	size_t neigh_vars_size;

	t = kmemdup(&neigh_sysctl_template, sizeof(*t), GFP_KERNEL_ACCOUNT);
	if (!t)
		goto err;

	for (i = 0; i < NEIGH_VAR_GC_INTERVAL; i++) {
		t->neigh_vars[i].data += (long) p;
		t->neigh_vars[i].extra1 = dev;
		t->neigh_vars[i].extra2 = p;
	}

	neigh_vars_size = ARRAY_SIZE(t->neigh_vars);
	if (dev) {
		dev_name_source = dev->name;
		/* Terminate the table early */
		neigh_vars_size = NEIGH_VAR_BASE_REACHABLE_TIME_MS + 1;
	} else {
		struct neigh_table *tbl = p->tbl;
		dev_name_source = "default";
		t->neigh_vars[NEIGH_VAR_GC_INTERVAL].data = &tbl->gc_interval;
		t->neigh_vars[NEIGH_VAR_GC_THRESH1].data = &tbl->gc_thresh1;
		t->neigh_vars[NEIGH_VAR_GC_THRESH2].data = &tbl->gc_thresh2;
		t->neigh_vars[NEIGH_VAR_GC_THRESH3].data = &tbl->gc_thresh3;
	}

	if (handler) {
		/* RetransTime */
		t->neigh_vars[NEIGH_VAR_RETRANS_TIME].proc_handler = handler;
		/* ReachableTime */
		t->neigh_vars[NEIGH_VAR_BASE_REACHABLE_TIME].proc_handler = handler;
		/* RetransTime (in milliseconds)*/
		t->neigh_vars[NEIGH_VAR_RETRANS_TIME_MS].proc_handler = handler;
		/* ReachableTime (in milliseconds) */
		t->neigh_vars[NEIGH_VAR_BASE_REACHABLE_TIME_MS].proc_handler = handler;
	} else {
		/* Those handlers will update p->reachable_time after
		 * base_reachable_time(_ms) is set to ensure the new timer starts being
		 * applied after the next neighbour update instead of waiting for
		 * neigh_periodic_work to update its value (can be multiple minutes)
		 * So any handler that replaces them should do this as well
		 */
		/* ReachableTime */
		t->neigh_vars[NEIGH_VAR_BASE_REACHABLE_TIME].proc_handler =
			neigh_proc_base_reachable_time;
		/* ReachableTime (in milliseconds) */
		t->neigh_vars[NEIGH_VAR_BASE_REACHABLE_TIME_MS].proc_handler =
			neigh_proc_base_reachable_time;
	}

	switch (neigh_parms_family(p)) {
	case AF_INET:
	      p_name = "ipv4";
	      break;
	case AF_INET6:
	      p_name = "ipv6";
	      break;
	default:
	      BUG();
	}

	snprintf(neigh_path, sizeof(neigh_path), "net/%s/neigh/%s",
		p_name, dev_name_source);
	t->sysctl_header = register_net_sysctl_sz(neigh_parms_net(p),
						  neigh_path, t->neigh_vars,
						  neigh_vars_size);
	if (!t->sysctl_header)
		goto free;

	p->sysctl_table = t;
	return 0;

free:
	kfree(t);
err:
	return -ENOBUFS;
}
EXPORT_SYMBOL(neigh_sysctl_register);

void neigh_sysctl_unregister(struct neigh_parms *p)
{
	if (p->sysctl_table) {
		struct neigh_sysctl_table *t = p->sysctl_table;
		p->sysctl_table = NULL;
		unregister_net_sysctl_table(t->sysctl_header);
		kfree(t);
	}
}
EXPORT_SYMBOL(neigh_sysctl_unregister);

#endif	/* CONFIG_SYSCTL */

static const struct rtnl_msg_handler neigh_rtnl_msg_handlers[] __initconst = {
	{.msgtype = RTM_NEWNEIGH, .doit = neigh_add},
	{.msgtype = RTM_DELNEIGH, .doit = neigh_delete},
	{.msgtype = RTM_GETNEIGH, .doit = neigh_get, .dumpit = neigh_dump_info,
	 .flags = RTNL_FLAG_DOIT_UNLOCKED | RTNL_FLAG_DUMP_UNLOCKED},
	{.msgtype = RTM_GETNEIGHTBL, .dumpit = neightbl_dump_info,
	 .flags = RTNL_FLAG_DUMP_UNLOCKED},
	{.msgtype = RTM_SETNEIGHTBL, .doit = neightbl_set,
	 .flags = RTNL_FLAG_DOIT_UNLOCKED},
};

static int __init neigh_init(void)
{
	rtnl_register_many(neigh_rtnl_msg_handlers);
	return 0;
}

subsys_initcall(neigh_init);