xref: /linux/net/batman-adv/bridge_loop_avoidance.c (revision 0e59523b440c90ed1899476f32ad4e949282f43e)

// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) B.A.T.M.A.N. contributors:
 *
 * Simon Wunderlich
 */

#include "bridge_loop_avoidance.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/bug.h>
#include <linux/byteorder/generic.h>
#include <linux/compiler.h>
#include <linux/container_of.h>
#include <linux/crc16.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/etherdevice.h>
#include <linux/gfp.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/jhash.h>
#include <linux/jiffies.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/sprintf.h>
#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/string_choices.h>
#include <linux/workqueue.h>
#include <net/arp.h>
#include <net/genetlink.h>
#include <net/netlink.h>
#include <uapi/linux/batadv_packet.h>
#include <uapi/linux/batman_adv.h>

#include "hard-interface.h"
#include "hash.h"
#include "log.h"
#include "netlink.h"
#include "originator.h"
#include "translation-table.h"

static const u8 batadv_announce_mac[4] = {0x43, 0x05, 0x43, 0x05};

static void batadv_bla_periodic_work(struct work_struct *work);
static void
batadv_bla_send_announce(struct batadv_priv *bat_priv,
			 struct batadv_bla_backbone_gw *backbone_gw);

/**
 * batadv_choose_claim() - choose the right bucket for a claim.
 * @data: data to hash
 * @size: size of the hash table
 *
 * Return: the hash index of the claim
 */
static inline u32 batadv_choose_claim(const void *data, u32 size)
{
	const struct batadv_bla_claim *claim = data;
	u32 hash = 0;

	hash = jhash(&claim->addr, sizeof(claim->addr), hash);
	hash = jhash(&claim->vid, sizeof(claim->vid), hash);

	return hash % size;
}

/**
 * batadv_choose_backbone_gw() - choose the right bucket for a backbone gateway.
 * @data: data to hash
 * @size: size of the hash table
 *
 * Return: the hash index of the backbone gateway
 */
static inline u32 batadv_choose_backbone_gw(const void *data, u32 size)
{
	const struct batadv_bla_backbone_gw *gw;
	u32 hash = 0;

	gw = data;
	hash = jhash(&gw->orig, sizeof(gw->orig), hash);
	hash = jhash(&gw->vid, sizeof(gw->vid), hash);

	return hash % size;
}

/**
 * batadv_compare_backbone_gw() - compare address and vid of two backbone gws
 * @node: list node of the first entry to compare
 * @data2: pointer to the second backbone gateway
 *
 * Return: true if the backbones have the same data, false otherwise
 */
static bool batadv_compare_backbone_gw(const struct hlist_node *node,
				       const void *data2)
{
	const void *data1 = container_of(node, struct batadv_bla_backbone_gw,
					 hash_entry);
	const struct batadv_bla_backbone_gw *gw1 = data1;
	const struct batadv_bla_backbone_gw *gw2 = data2;

	if (!batadv_compare_eth(gw1->orig, gw2->orig))
		return false;

	if (gw1->vid != gw2->vid)
		return false;

	return true;
}

/**
 * batadv_compare_claim() - compare address and vid of two claims
 * @node: list node of the first entry to compare
 * @data2: pointer to the second claims
 *
 * Return: true if the claims have the same data, false otherwise
 */
static bool batadv_compare_claim(const struct hlist_node *node,
				 const void *data2)
{
	const void *data1 = container_of(node, struct batadv_bla_claim,
					 hash_entry);
	const struct batadv_bla_claim *cl1 = data1;
	const struct batadv_bla_claim *cl2 = data2;

	if (!batadv_compare_eth(cl1->addr, cl2->addr))
		return false;

	if (cl1->vid != cl2->vid)
		return false;

	return true;
}

/**
 * batadv_backbone_gw_release() - release backbone gw from lists and queue for
 *  free after rcu grace period
 * @ref: kref pointer of the backbone gw
 */
static void batadv_backbone_gw_release(struct kref *ref)
{
	struct batadv_bla_backbone_gw *backbone_gw;

	backbone_gw = container_of(ref, struct batadv_bla_backbone_gw,
				   refcount);

	kfree_rcu(backbone_gw, rcu);
}

/**
 * batadv_backbone_gw_put() - decrement the backbone gw refcounter and possibly
 *  release it
 * @backbone_gw: backbone gateway to be free'd
 */
static void batadv_backbone_gw_put(struct batadv_bla_backbone_gw *backbone_gw)
{
	if (!backbone_gw)
		return;

	kref_put(&backbone_gw->refcount, batadv_backbone_gw_release);
}

/**
 * batadv_claim_release() - release claim from lists and queue for free after
 *  rcu grace period
 * @ref: kref pointer of the claim
 */
static void batadv_claim_release(struct kref *ref)
{
	struct batadv_bla_backbone_gw *old_backbone_gw;
	struct batadv_bla_claim *claim;

	claim = container_of(ref, struct batadv_bla_claim, refcount);

	spin_lock_bh(&claim->backbone_lock);
	old_backbone_gw = claim->backbone_gw;
	claim->backbone_gw = NULL;
	spin_unlock_bh(&claim->backbone_lock);

	spin_lock_bh(&old_backbone_gw->crc_lock);
	old_backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
	spin_unlock_bh(&old_backbone_gw->crc_lock);

	batadv_backbone_gw_put(old_backbone_gw);

	kfree_rcu(claim, rcu);
}

/**
 * batadv_claim_put() - decrement the claim refcounter and possibly release it
 * @claim: claim to be free'd
 */
static void batadv_claim_put(struct batadv_bla_claim *claim)
{
	if (!claim)
		return;

	kref_put(&claim->refcount, batadv_claim_release);
}

/**
 * batadv_claim_hash_find() - looks for a claim in the claim hash
 * @bat_priv: the bat priv with all the mesh interface information
 * @data: search data (may be local/static data)
 *
 * Return: claim if found or NULL otherwise.
 */
static struct batadv_bla_claim *
batadv_claim_hash_find(struct batadv_priv *bat_priv,
		       struct batadv_bla_claim *data)
{
	struct batadv_hashtable *hash = bat_priv->bla.claim_hash;
	struct batadv_bla_claim *claim_tmp = NULL;
	struct batadv_bla_claim *claim;
	struct hlist_head *head;
	int index;

	if (!hash)
		return NULL;

	index = batadv_choose_claim(data, hash->size);
	head = &hash->table[index];

	rcu_read_lock();
	hlist_for_each_entry_rcu(claim, head, hash_entry) {
		if (!batadv_compare_claim(&claim->hash_entry, data))
			continue;

		if (!kref_get_unless_zero(&claim->refcount))
			continue;

		claim_tmp = claim;
		break;
	}
	rcu_read_unlock();

	return claim_tmp;
}

/**
 * batadv_backbone_hash_find() - looks for a backbone gateway in the hash
 * @bat_priv: the bat priv with all the mesh interface information
 * @addr: the address of the originator
 * @vid: the VLAN ID
 *
 * Return: backbone gateway if found or NULL otherwise
 */
static struct batadv_bla_backbone_gw *
batadv_backbone_hash_find(struct batadv_priv *bat_priv, const u8 *addr,
			  unsigned short vid)
{
	struct batadv_hashtable *hash = bat_priv->bla.backbone_hash;
	struct batadv_bla_backbone_gw *backbone_gw_tmp = NULL;
	struct batadv_bla_backbone_gw search_entry;
	struct batadv_bla_backbone_gw *backbone_gw;
	struct hlist_head *head;
	int index;

	if (!hash)
		return NULL;

	ether_addr_copy(search_entry.orig, addr);
	search_entry.vid = vid;

	index = batadv_choose_backbone_gw(&search_entry, hash->size);
	head = &hash->table[index];

	rcu_read_lock();
	hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
		if (!batadv_compare_backbone_gw(&backbone_gw->hash_entry,
						&search_entry))
			continue;

		if (!kref_get_unless_zero(&backbone_gw->refcount))
			continue;

		backbone_gw_tmp = backbone_gw;
		break;
	}
	rcu_read_unlock();

	return backbone_gw_tmp;
}

/**
 * batadv_bla_del_backbone_claims() - delete all claims for a backbone
 * @backbone_gw: backbone gateway where the claims should be removed
 */
static void
batadv_bla_del_backbone_claims(struct batadv_bla_backbone_gw *backbone_gw)
{
	spinlock_t *list_lock;	/* protects write access to the hash lists */
	struct batadv_bla_claim *claim;
	struct batadv_hashtable *hash;
	struct hlist_node *node_tmp;
	struct hlist_head *head;
	int i;

	hash = backbone_gw->bat_priv->bla.claim_hash;
	if (!hash)
		return;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];
		list_lock = &hash->list_locks[i];

		spin_lock_bh(list_lock);
		hlist_for_each_entry_safe(claim, node_tmp,
					  head, hash_entry) {
			if (claim->backbone_gw != backbone_gw)
				continue;

			hlist_del_rcu(&claim->hash_entry);
			batadv_claim_put(claim);
		}
		spin_unlock_bh(list_lock);
	}
}

/**
 * batadv_bla_send_claim() - sends a claim frame according to the provided info
 * @bat_priv: the bat priv with all the mesh interface information
 * @mac: the mac address to be announced within the claim
 * @vid: the VLAN ID
 * @claimtype: the type of the claim (CLAIM, UNCLAIM, ANNOUNCE, ...)
 */
static void batadv_bla_send_claim(struct batadv_priv *bat_priv, const u8 *mac,
				  unsigned short vid, int claimtype)
{
	struct batadv_bla_claim_dst local_claim_dest;
	struct batadv_hard_iface *primary_if;
	struct ethhdr *ethhdr;
	struct sk_buff *skb;
	__be32 zeroip = 0;
	u8 *hw_src;

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if)
		return;

	memcpy(&local_claim_dest, &bat_priv->bla.claim_dest,
	       sizeof(local_claim_dest));
	local_claim_dest.type = claimtype;

	skb = arp_create(ARPOP_REPLY, ETH_P_ARP,
			 /* IP DST: 0.0.0.0 */
			 zeroip,
			 primary_if->mesh_iface,
			 /* IP SRC: 0.0.0.0 */
			 zeroip,
			 /* Ethernet DST: Broadcast */
			 NULL,
			 /* Ethernet SRC/HW SRC:  originator mac */
			 primary_if->net_dev->dev_addr,
			 /* HW DST: FF:43:05:XX:YY:YY
			  * with XX   = claim type
			  * and YY:YY = group id
			  */
			 (u8 *)&local_claim_dest);

	if (!skb)
		goto out;

	ethhdr = (struct ethhdr *)skb->data;
	hw_src = (u8 *)ethhdr + ETH_HLEN + sizeof(struct arphdr);

	/* now we pretend that the client would have sent this ... */
	switch (claimtype) {
	case BATADV_CLAIM_TYPE_CLAIM:
		/* normal claim frame
		 * set Ethernet SRC to the clients mac
		 */
		ether_addr_copy(ethhdr->h_source, mac);
		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "%s(): CLAIM %pM on vid %d\n", __func__, mac,
			   batadv_print_vid(vid));
		break;
	case BATADV_CLAIM_TYPE_UNCLAIM:
		/* unclaim frame
		 * set HW SRC to the clients mac
		 */
		ether_addr_copy(hw_src, mac);
		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "%s(): UNCLAIM %pM on vid %d\n", __func__, mac,
			   batadv_print_vid(vid));
		break;
	case BATADV_CLAIM_TYPE_ANNOUNCE:
		/* announcement frame
		 * set HW SRC to the special mac containing the crc
		 */
		ether_addr_copy(hw_src, mac);
		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "%s(): ANNOUNCE of %pM on vid %d\n", __func__,
			   ethhdr->h_source, batadv_print_vid(vid));
		break;
	case BATADV_CLAIM_TYPE_REQUEST:
		/* request frame
		 * set HW SRC and header destination to the receiving backbone
		 * gws mac
		 */
		ether_addr_copy(hw_src, mac);
		ether_addr_copy(ethhdr->h_dest, mac);
		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "%s(): REQUEST of %pM to %pM on vid %d\n", __func__,
			   ethhdr->h_source, ethhdr->h_dest,
			   batadv_print_vid(vid));
		break;
	case BATADV_CLAIM_TYPE_LOOPDETECT:
		ether_addr_copy(ethhdr->h_source, mac);
		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "%s(): LOOPDETECT of %pM to %pM on vid %d\n",
			   __func__, ethhdr->h_source, ethhdr->h_dest,
			   batadv_print_vid(vid));

		break;
	}

	if (vid & BATADV_VLAN_HAS_TAG) {
		skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
				      vid & VLAN_VID_MASK);
		if (!skb)
			goto out;
	}

	skb_reset_mac_header(skb);
	skb->protocol = eth_type_trans(skb, primary_if->mesh_iface);
	batadv_inc_counter(bat_priv, BATADV_CNT_RX);
	batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
			   skb->len + ETH_HLEN);

	netif_rx(skb);
out:
	batadv_hardif_put(primary_if);
}

/**
 * batadv_bla_loopdetect_report() - worker for reporting the loop
 * @work: work queue item
 *
 * Throws an uevent, as the loopdetect check function can't do that itself
 * since the kernel may sleep while throwing uevents.
 */
static void batadv_bla_loopdetect_report(struct work_struct *work)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	struct batadv_priv *bat_priv;
	char vid_str[6] = { '\0' };

	backbone_gw = container_of(work, struct batadv_bla_backbone_gw,
				   report_work);
	bat_priv = backbone_gw->bat_priv;

	batadv_info(bat_priv->mesh_iface,
		    "Possible loop on VLAN %d detected which can't be handled by BLA - please check your network setup!\n",
		    batadv_print_vid(backbone_gw->vid));
	snprintf(vid_str, sizeof(vid_str), "%d",
		 batadv_print_vid(backbone_gw->vid));
	vid_str[sizeof(vid_str) - 1] = 0;

	batadv_throw_uevent(bat_priv, BATADV_UEV_BLA, BATADV_UEV_LOOPDETECT,
			    vid_str);

	batadv_backbone_gw_put(backbone_gw);
}

/**
 * batadv_bla_get_backbone_gw() - finds or creates a backbone gateway
 * @bat_priv: the bat priv with all the mesh interface information
 * @orig: the mac address of the originator
 * @vid: the VLAN ID
 * @own_backbone: set if the requested backbone is local
 *
 * Return: the (possibly created) backbone gateway or NULL on error
 */
static struct batadv_bla_backbone_gw *
batadv_bla_get_backbone_gw(struct batadv_priv *bat_priv, const u8 *orig,
			   unsigned short vid, bool own_backbone)
{
	struct batadv_bla_backbone_gw *entry;
	struct batadv_orig_node *orig_node;
	int hash_added;

	entry = batadv_backbone_hash_find(bat_priv, orig, vid);

	if (entry)
		return entry;

	batadv_dbg(BATADV_DBG_BLA, bat_priv,
		   "%s(): not found (%pM, %d), creating new entry\n", __func__,
		   orig, batadv_print_vid(vid));

	entry = kzalloc_obj(*entry, GFP_ATOMIC);
	if (!entry)
		return NULL;

	entry->vid = vid;
	WRITE_ONCE(entry->lasttime, jiffies);
	entry->crc = BATADV_BLA_CRC_INIT;
	entry->bat_priv = bat_priv;
	spin_lock_init(&entry->crc_lock);
	entry->state = BATADV_BLA_BACKBONE_GW_SYNCED;
	entry->wait_periods = 0;
	ether_addr_copy(entry->orig, orig);
	INIT_WORK(&entry->report_work, batadv_bla_loopdetect_report);
	kref_init(&entry->refcount);

	kref_get(&entry->refcount);
	hash_added = batadv_hash_add(bat_priv->bla.backbone_hash,
				     batadv_compare_backbone_gw,
				     batadv_choose_backbone_gw, entry,
				     &entry->hash_entry);

	if (unlikely(hash_added != 0)) {
		/* hash failed, free the structure */
		kfree(entry);
		return NULL;
	}

	/* this is a gateway now, remove any TT entry on this VLAN */
	orig_node = batadv_orig_hash_find(bat_priv, orig);
	if (orig_node) {
		batadv_tt_global_del_orig(bat_priv, orig_node, vid,
					  "became a backbone gateway");
		batadv_orig_node_put(orig_node);
	}

	if (own_backbone) {
		batadv_bla_send_announce(bat_priv, entry);

		/* this will be decreased in the worker thread */
		spin_lock_bh(&bat_priv->bla.num_requests_lock);
		if (entry->state == BATADV_BLA_BACKBONE_GW_SYNCED) {
			entry->state = BATADV_BLA_BACKBONE_GW_UNSYNCED;
			entry->wait_periods = BATADV_BLA_WAIT_PERIODS;
			atomic_inc(&bat_priv->bla.num_requests);
		}
		spin_unlock_bh(&bat_priv->bla.num_requests_lock);
	}

	return entry;
}

/**
 * batadv_bla_update_own_backbone_gw() - updates the own backbone gw for a VLAN
 * @bat_priv: the bat priv with all the mesh interface information
 * @primary_if: the selected primary interface
 * @vid: VLAN identifier
 *
 * update or add the own backbone gw to make sure we announce
 * where we receive other backbone gws
 */
static void
batadv_bla_update_own_backbone_gw(struct batadv_priv *bat_priv,
				  struct batadv_hard_iface *primary_if,
				  unsigned short vid)
{
	struct batadv_bla_backbone_gw *backbone_gw;

	backbone_gw = batadv_bla_get_backbone_gw(bat_priv,
						 primary_if->net_dev->dev_addr,
						 vid, true);
	if (unlikely(!backbone_gw))
		return;

	WRITE_ONCE(backbone_gw->lasttime, jiffies);
	batadv_backbone_gw_put(backbone_gw);
}

/**
 * batadv_bla_answer_request() - answer a bla request by sending own claims
 * @bat_priv: the bat priv with all the mesh interface information
 * @primary_if: interface where the request came on
 * @vid: the vid where the request came on
 *
 * Repeat all of our own claims, and finally send an ANNOUNCE frame
 * to allow the requester another check if the CRC is correct now.
 */
static void batadv_bla_answer_request(struct batadv_priv *bat_priv,
				      struct batadv_hard_iface *primary_if,
				      unsigned short vid)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	struct batadv_bla_claim *claim;
	struct batadv_hashtable *hash;
	struct hlist_head *head;
	int i;

	batadv_dbg(BATADV_DBG_BLA, bat_priv,
		   "%s(): received a claim request, send all of our own claims again\n",
		   __func__);

	backbone_gw = batadv_backbone_hash_find(bat_priv,
						primary_if->net_dev->dev_addr,
						vid);
	if (!backbone_gw)
		return;

	hash = bat_priv->bla.claim_hash;
	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(claim, head, hash_entry) {
			/* only own claims are interesting */
			if (claim->backbone_gw != backbone_gw)
				continue;

			batadv_bla_send_claim(bat_priv, claim->addr, claim->vid,
					      BATADV_CLAIM_TYPE_CLAIM);
		}
		rcu_read_unlock();
	}

	/* finally, send an announcement frame */
	batadv_bla_send_announce(bat_priv, backbone_gw);
	batadv_backbone_gw_put(backbone_gw);
}

/**
 * batadv_bla_send_request() - send a request to repeat claims
 * @backbone_gw: the backbone gateway from whom we are out of sync
 *
 * When the crc is wrong, ask the backbone gateway for a full table update.
 * After the request, it will repeat all of his own claims and finally
 * send an announcement claim with which we can check again.
 */
static void batadv_bla_send_request(struct batadv_bla_backbone_gw *backbone_gw)
{
	/* first, remove all old entries */
	batadv_bla_del_backbone_claims(backbone_gw);

	batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,
		   "Sending REQUEST to %pM\n", backbone_gw->orig);

	/* send request */
	batadv_bla_send_claim(backbone_gw->bat_priv, backbone_gw->orig,
			      backbone_gw->vid, BATADV_CLAIM_TYPE_REQUEST);

	/* no local broadcasts should be sent or received, for now. */
	spin_lock_bh(&backbone_gw->bat_priv->bla.num_requests_lock);
	if (backbone_gw->state == BATADV_BLA_BACKBONE_GW_SYNCED) {
		backbone_gw->state = BATADV_BLA_BACKBONE_GW_UNSYNCED;
		atomic_inc(&backbone_gw->bat_priv->bla.num_requests);
	}
	spin_unlock_bh(&backbone_gw->bat_priv->bla.num_requests_lock);
}

/**
 * batadv_bla_send_announce() - Send an announcement frame
 * @bat_priv: the bat priv with all the mesh interface information
 * @backbone_gw: our backbone gateway which should be announced
 */
static void batadv_bla_send_announce(struct batadv_priv *bat_priv,
				     struct batadv_bla_backbone_gw *backbone_gw)
{
	u8 mac[ETH_ALEN] __aligned(2);
	__be16 crc;

	memcpy(mac, batadv_announce_mac, 4);
	spin_lock_bh(&backbone_gw->crc_lock);
	crc = htons(backbone_gw->crc);
	spin_unlock_bh(&backbone_gw->crc_lock);
	memcpy(&mac[4], &crc, 2);

	batadv_bla_send_claim(bat_priv, mac, backbone_gw->vid,
			      BATADV_CLAIM_TYPE_ANNOUNCE);
}

/**
 * batadv_bla_add_claim() - Adds a claim in the claim hash
 * @bat_priv: the bat priv with all the mesh interface information
 * @mac: the mac address of the claim
 * @vid: the VLAN ID of the frame
 * @backbone_gw: the backbone gateway which claims it
 */
static void batadv_bla_add_claim(struct batadv_priv *bat_priv,
				 const u8 *mac, const unsigned short vid,
				 struct batadv_bla_backbone_gw *backbone_gw)
{
	struct batadv_bla_backbone_gw *old_backbone_gw;
	struct batadv_bla_claim search_claim;
	struct batadv_bla_claim *claim;
	int hash_added;
	u16 claim_crc;
	bool changed;

	ether_addr_copy(search_claim.addr, mac);
	search_claim.vid = vid;
	claim = batadv_claim_hash_find(bat_priv, &search_claim);
	claim_crc = crc16(0, mac, ETH_ALEN);

	/* create a new claim entry if it does not exist yet. */
	if (!claim) {
		claim = kzalloc_obj(*claim, GFP_ATOMIC);
		if (!claim)
			return;

		ether_addr_copy(claim->addr, mac);
		spin_lock_init(&claim->backbone_lock);
		claim->vid = vid;
		WRITE_ONCE(claim->lasttime, jiffies);
		kref_get(&backbone_gw->refcount);
		claim->backbone_gw = backbone_gw;
		kref_init(&claim->refcount);

		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "%s(): adding new entry %pM, vid %d to hash ...\n",
			   __func__, mac, batadv_print_vid(vid));

		kref_get(&claim->refcount);
		hash_added = batadv_hash_add(bat_priv->bla.claim_hash,
					     batadv_compare_claim,
					     batadv_choose_claim, claim,
					     &claim->hash_entry);

		if (unlikely(hash_added != 0)) {
			/* only local changes happened. */
			batadv_backbone_gw_put(backbone_gw);
			kfree(claim);
			return;
		}

		spin_lock_bh(&backbone_gw->crc_lock);
		backbone_gw->crc ^= claim_crc;
		spin_unlock_bh(&backbone_gw->crc_lock);

		WRITE_ONCE(backbone_gw->lasttime, jiffies);

		batadv_claim_put(claim);
		return;
	}

	WRITE_ONCE(claim->lasttime, jiffies);

	/* replace backbone_gw atomically and adjust reference counters */
	spin_lock_bh(&claim->backbone_lock);
	if (claim->backbone_gw != backbone_gw) {
		changed = true;

		old_backbone_gw = claim->backbone_gw;
		kref_get(&backbone_gw->refcount);
		claim->backbone_gw = backbone_gw;
	} else {
		old_backbone_gw = NULL;
		changed = false;
	}
	spin_unlock_bh(&claim->backbone_lock);

	if (changed) {
		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "%s(): changing ownership for %pM, vid %d to gw %pM\n",
			   __func__, mac, batadv_print_vid(vid),
			   backbone_gw->orig);

		/* add claim address to new backbone_gw */
		spin_lock_bh(&backbone_gw->crc_lock);
		backbone_gw->crc ^= claim_crc;
		spin_unlock_bh(&backbone_gw->crc_lock);

		WRITE_ONCE(backbone_gw->lasttime, jiffies);
	}

	if (old_backbone_gw) {
		/* remove claim address from old backbone_gw */
		spin_lock_bh(&old_backbone_gw->crc_lock);
		old_backbone_gw->crc ^= claim_crc;
		spin_unlock_bh(&old_backbone_gw->crc_lock);

		batadv_backbone_gw_put(old_backbone_gw);
	}

	batadv_claim_put(claim);
}

/**
 * batadv_bla_claim_get_backbone_gw() - Get valid reference for backbone_gw of
 *  claim
 * @claim: claim whose backbone_gw should be returned
 *
 * Return: valid reference to claim::backbone_gw
 */
static struct batadv_bla_backbone_gw *
batadv_bla_claim_get_backbone_gw(struct batadv_bla_claim *claim)
{
	struct batadv_bla_backbone_gw *backbone_gw;

	spin_lock_bh(&claim->backbone_lock);
	backbone_gw = claim->backbone_gw;
	kref_get(&backbone_gw->refcount);
	spin_unlock_bh(&claim->backbone_lock);

	return backbone_gw;
}

/**
 * batadv_bla_del_claim() - delete a claim from the claim hash
 * @bat_priv: the bat priv with all the mesh interface information
 * @mac: mac address of the claim to be removed
 * @vid: VLAN id for the claim to be removed
 */
static void batadv_bla_del_claim(struct batadv_priv *bat_priv,
				 const u8 *mac, const unsigned short vid)
{
	struct batadv_bla_claim *claim_removed_entry;
	struct hlist_node *claim_removed_node;
	struct batadv_bla_claim search_claim;
	struct batadv_bla_claim *claim;

	ether_addr_copy(search_claim.addr, mac);
	search_claim.vid = vid;
	claim = batadv_claim_hash_find(bat_priv, &search_claim);
	if (!claim)
		return;

	batadv_dbg(BATADV_DBG_BLA, bat_priv, "%s(): %pM, vid %d\n", __func__,
		   mac, batadv_print_vid(vid));

	claim_removed_node = batadv_hash_remove(bat_priv->bla.claim_hash,
						batadv_compare_claim,
						batadv_choose_claim, claim);
	if (!claim_removed_node)
		goto free_claim;

	/* reference from the hash is gone */
	claim_removed_entry = hlist_entry(claim_removed_node,
					  struct batadv_bla_claim, hash_entry);
	batadv_claim_put(claim_removed_entry);

free_claim:
	/* don't need the reference from hash_find() anymore */
	batadv_claim_put(claim);
}

/**
 * batadv_handle_announce() - check for ANNOUNCE frame
 * @bat_priv: the bat priv with all the mesh interface information
 * @an_addr: announcement mac address (ARP Sender HW address)
 * @backbone_addr: originator address of the sender (Ethernet source MAC)
 * @vid: the VLAN ID of the frame
 *
 * Return: true if handled
 */
static bool batadv_handle_announce(struct batadv_priv *bat_priv, u8 *an_addr,
				   u8 *backbone_addr, unsigned short vid)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	u16 backbone_crc;
	u16 crc;

	if (memcmp(an_addr, batadv_announce_mac, 4) != 0)
		return false;

	backbone_gw = batadv_bla_get_backbone_gw(bat_priv, backbone_addr, vid,
						 false);

	if (unlikely(!backbone_gw))
		return true;

	/* handle as ANNOUNCE frame */
	WRITE_ONCE(backbone_gw->lasttime, jiffies);
	crc = ntohs(*((__force __be16 *)(&an_addr[4])));

	batadv_dbg(BATADV_DBG_BLA, bat_priv,
		   "%s(): ANNOUNCE vid %d (sent by %pM)... CRC = %#.4x\n",
		   __func__, batadv_print_vid(vid), backbone_gw->orig, crc);

	spin_lock_bh(&backbone_gw->crc_lock);
	backbone_crc = backbone_gw->crc;
	spin_unlock_bh(&backbone_gw->crc_lock);

	if (backbone_crc != crc) {
		batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,
			   "%s(): CRC FAILED for %pM/%d (my = %#.4x, sent = %#.4x)\n",
			   __func__, backbone_gw->orig,
			   batadv_print_vid(backbone_gw->vid),
			   backbone_crc, crc);

		batadv_bla_send_request(backbone_gw);
	} else {
		/* if we have sent a request and the crc was OK,
		 * we can allow traffic again.
		 */
		spin_lock_bh(&bat_priv->bla.num_requests_lock);
		if (backbone_gw->state == BATADV_BLA_BACKBONE_GW_UNSYNCED) {
			backbone_gw->state = BATADV_BLA_BACKBONE_GW_SYNCED;
			atomic_dec(&backbone_gw->bat_priv->bla.num_requests);
		}
		spin_unlock_bh(&bat_priv->bla.num_requests_lock);
	}

	batadv_backbone_gw_put(backbone_gw);
	return true;
}

/**
 * batadv_handle_request() - check for REQUEST frame
 * @bat_priv: the bat priv with all the mesh interface information
 * @primary_if: the primary hard interface of this batman mesh interface
 * @backbone_addr: backbone address to be requested (ARP sender HW MAC)
 * @ethhdr: ethernet header of a packet
 * @vid: the VLAN ID of the frame
 *
 * Return: true if handled
 */
static bool batadv_handle_request(struct batadv_priv *bat_priv,
				  struct batadv_hard_iface *primary_if,
				  u8 *backbone_addr, struct ethhdr *ethhdr,
				  unsigned short vid)
{
	/* check for REQUEST frame */
	if (!batadv_compare_eth(backbone_addr, ethhdr->h_dest))
		return false;

	/* sanity check, this should not happen on a normal switch,
	 * we ignore it in this case.
	 */
	if (!batadv_compare_eth(ethhdr->h_dest, primary_if->net_dev->dev_addr))
		return true;

	batadv_dbg(BATADV_DBG_BLA, bat_priv,
		   "%s(): REQUEST vid %d (sent by %pM)...\n",
		   __func__, batadv_print_vid(vid), ethhdr->h_source);

	batadv_bla_answer_request(bat_priv, primary_if, vid);
	return true;
}

/**
 * batadv_handle_unclaim() - check for UNCLAIM frame
 * @bat_priv: the bat priv with all the mesh interface information
 * @primary_if: the primary hard interface of this batman mesh interface
 * @backbone_addr: originator address of the backbone (Ethernet source)
 * @claim_addr: Client to be unclaimed (ARP sender HW MAC)
 * @vid: the VLAN ID of the frame
 *
 * Return: true if handled
 */
static bool batadv_handle_unclaim(struct batadv_priv *bat_priv,
				  struct batadv_hard_iface *primary_if,
				  const u8 *backbone_addr, const u8 *claim_addr,
				  unsigned short vid)
{
	/* unclaim in any case if it is our own */
	if (primary_if && batadv_compare_eth(backbone_addr,
					     primary_if->net_dev->dev_addr))
		batadv_bla_send_claim(bat_priv, claim_addr, vid,
				      BATADV_CLAIM_TYPE_UNCLAIM);

	/* this must be an UNCLAIM frame */
	batadv_dbg(BATADV_DBG_BLA, bat_priv,
		   "%s(): UNCLAIM %pM on vid %d (sent by %pM)...\n", __func__,
		   claim_addr, batadv_print_vid(vid), backbone_addr);

	batadv_bla_del_claim(bat_priv, claim_addr, vid);
	return true;
}

/**
 * batadv_handle_claim() - check for CLAIM frame
 * @bat_priv: the bat priv with all the mesh interface information
 * @primary_if: the primary hard interface of this batman mesh interface
 * @backbone_addr: originator address of the backbone (Ethernet Source)
 * @claim_addr: client mac address to be claimed (ARP sender HW MAC)
 * @vid: the VLAN ID of the frame
 *
 * Return: true if handled
 */
static bool batadv_handle_claim(struct batadv_priv *bat_priv,
				struct batadv_hard_iface *primary_if,
				const u8 *backbone_addr, const u8 *claim_addr,
				unsigned short vid)
{
	struct batadv_bla_backbone_gw *backbone_gw;

	/* register the gateway if not yet available, and add the claim. */

	backbone_gw = batadv_bla_get_backbone_gw(bat_priv, backbone_addr, vid,
						 false);

	if (unlikely(!backbone_gw))
		return true;

	/* this must be a CLAIM frame */
	batadv_bla_add_claim(bat_priv, claim_addr, vid, backbone_gw);
	if (batadv_compare_eth(backbone_addr, primary_if->net_dev->dev_addr))
		batadv_bla_send_claim(bat_priv, claim_addr, vid,
				      BATADV_CLAIM_TYPE_CLAIM);

	/* TODO: we could call something like tt_local_del() here. */

	batadv_backbone_gw_put(backbone_gw);
	return true;
}

/**
 * batadv_check_claim_group() - check for claim group membership
 * @bat_priv: the bat priv with all the mesh interface information
 * @primary_if: the primary interface of this batman interface
 * @hw_src: the Hardware source in the ARP Header
 * @hw_dst: the Hardware destination in the ARP Header
 * @ethhdr: pointer to the Ethernet header of the claim frame
 *
 * checks if it is a claim packet and if it's on the same group.
 * This function also applies the group ID of the sender
 * if it is in the same mesh.
 *
 * Return:
 *	2  - if it is a claim packet and on the same group
 *	1  - if is a claim packet from another group
 *	0  - if it is not a claim packet
 */
static int batadv_check_claim_group(struct batadv_priv *bat_priv,
				    struct batadv_hard_iface *primary_if,
				    u8 *hw_src, u8 *hw_dst,
				    struct ethhdr *ethhdr)
{
	struct batadv_bla_claim_dst *bla_dst_own;
	struct batadv_bla_claim_dst *bla_dst;
	struct batadv_orig_node *orig_node;
	u8 *backbone_addr;

	bla_dst = (struct batadv_bla_claim_dst *)hw_dst;
	bla_dst_own = &bat_priv->bla.claim_dest;

	/* if announcement packet, use the source,
	 * otherwise assume it is in the hw_src
	 */
	switch (bla_dst->type) {
	case BATADV_CLAIM_TYPE_CLAIM:
		backbone_addr = hw_src;
		break;
	case BATADV_CLAIM_TYPE_REQUEST:
	case BATADV_CLAIM_TYPE_ANNOUNCE:
	case BATADV_CLAIM_TYPE_UNCLAIM:
		backbone_addr = ethhdr->h_source;
		break;
	default:
		return 0;
	}

	/* don't accept claim frames from ourselves */
	if (batadv_compare_eth(backbone_addr, primary_if->net_dev->dev_addr))
		return 0;

	/* if its already the same group, it is fine. */
	if (bla_dst->group == bla_dst_own->group)
		return 2;

	/* lets see if this originator is in our mesh */
	orig_node = batadv_orig_hash_find(bat_priv, backbone_addr);

	/* don't accept claims from gateways which are not in
	 * the same mesh or group.
	 */
	if (!orig_node)
		return 1;

	/* if our mesh friends mac is bigger, use it for ourselves. */
	if (ntohs(bla_dst->group) > ntohs(bla_dst_own->group)) {
		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "taking other backbones claim group: %#.4x\n",
			   ntohs(bla_dst->group));
		bla_dst_own->group = bla_dst->group;
	}

	batadv_orig_node_put(orig_node);

	return 2;
}

/**
 * batadv_bla_process_claim() - Check if this is a claim frame, and process it
 * @bat_priv: the bat priv with all the mesh interface information
 * @primary_if: the primary hard interface of this batman mesh interface
 * @skb: the frame to be checked
 *
 * Warning: This function may reallocate the skb data buffer via
 * batadv_get_vid()/... Any pointer into the skb data (e.g. obtained
 * from skb->data or eth_hdr()) before this call must be considered
 * invalid afterwards and has to be reacquired.
 *
 * Return: true if it was a claim frame, otherwise return false to
 * tell the callee that it can use the frame on its own.
 */
static bool batadv_bla_process_claim(struct batadv_priv *bat_priv,
				     struct batadv_hard_iface *primary_if,
				     struct sk_buff *skb)
{
	struct batadv_bla_claim_dst *bla_dst_own;
	struct batadv_bla_claim_dst *bla_dst;
	struct vlan_hdr vhdr_buf;
	struct vlan_hdr *vhdr;
	struct ethhdr *ethhdr;
	struct arphdr *arphdr;
	unsigned short vid;
	int vlan_depth = 0;
	__be16 proto;
	int headlen;
	u8 *hw_src;
	u8 *hw_dst;
	int ret;

	vid = batadv_get_vid(skb, 0);
	ethhdr = eth_hdr(skb);

	proto = ethhdr->h_proto;
	headlen = ETH_HLEN;
	if (vid & BATADV_VLAN_HAS_TAG) {
		/* Traverse the VLAN/Ethertypes.
		 *
		 * At this point it is known that the first protocol is a VLAN
		 * header, so start checking at the encapsulated protocol.
		 *
		 * The depth of the VLAN headers is recorded to drop BLA claim
		 * frames encapsulated into multiple VLAN headers (QinQ).
		 */
		do {
			vhdr = skb_header_pointer(skb, headlen, VLAN_HLEN,
						  &vhdr_buf);
			if (!vhdr)
				return false;

			proto = vhdr->h_vlan_encapsulated_proto;
			headlen += VLAN_HLEN;
			vlan_depth++;
		} while (proto == htons(ETH_P_8021Q));
	}

	if (proto != htons(ETH_P_ARP))
		return false; /* not a claim frame */

	/* this must be a ARP frame. check if it is a claim. */

	if (unlikely(!pskb_may_pull(skb, headlen + arp_hdr_len(skb->dev))))
		return false;

	/* pskb_may_pull() may have modified the pointers, get ethhdr again */
	ethhdr = eth_hdr(skb);
	arphdr = (struct arphdr *)((u8 *)ethhdr + headlen);

	/* Check whether the ARP frame carries a valid
	 * IP information
	 */
	if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
		return false;
	if (arphdr->ar_pro != htons(ETH_P_IP))
		return false;
	if (arphdr->ar_hln != ETH_ALEN)
		return false;
	if (arphdr->ar_pln != 4)
		return false;

	hw_src = (u8 *)arphdr + sizeof(struct arphdr);
	hw_dst = hw_src + ETH_ALEN + 4;
	bla_dst = (struct batadv_bla_claim_dst *)hw_dst;
	bla_dst_own = &bat_priv->bla.claim_dest;

	/* check if it is a claim frame in general */
	if (memcmp(bla_dst->magic, bla_dst_own->magic,
		   sizeof(bla_dst->magic)) != 0)
		return false;

	/* check if there is a claim frame encapsulated deeper in (QinQ) and
	 * drop that, as this is not supported by BLA but should also not be
	 * sent via the mesh.
	 */
	if (vlan_depth > 1)
		return true;

	/* Let the loopdetect frames on the mesh in any case. */
	if (bla_dst->type == BATADV_CLAIM_TYPE_LOOPDETECT)
		return false;

	/* check if it is a claim frame. */
	ret = batadv_check_claim_group(bat_priv, primary_if, hw_src, hw_dst,
				       ethhdr);
	if (ret == 1)
		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "%s(): received a claim frame from another group. From: %pM on vid %d ...(hw_src %pM, hw_dst %pM)\n",
			   __func__, ethhdr->h_source, batadv_print_vid(vid),
			   hw_src, hw_dst);

	if (ret < 2)
		return !!ret;

	/* become a backbone gw ourselves on this vlan if not happened yet */
	batadv_bla_update_own_backbone_gw(bat_priv, primary_if, vid);

	/* check for the different types of claim frames ... */
	switch (bla_dst->type) {
	case BATADV_CLAIM_TYPE_CLAIM:
		if (batadv_handle_claim(bat_priv, primary_if, hw_src,
					ethhdr->h_source, vid))
			return true;
		break;
	case BATADV_CLAIM_TYPE_UNCLAIM:
		if (batadv_handle_unclaim(bat_priv, primary_if,
					  ethhdr->h_source, hw_src, vid))
			return true;
		break;

	case BATADV_CLAIM_TYPE_ANNOUNCE:
		if (batadv_handle_announce(bat_priv, hw_src, ethhdr->h_source,
					   vid))
			return true;
		break;
	case BATADV_CLAIM_TYPE_REQUEST:
		if (batadv_handle_request(bat_priv, primary_if, hw_src, ethhdr,
					  vid))
			return true;
		break;
	}

	batadv_dbg(BATADV_DBG_BLA, bat_priv,
		   "%s(): ERROR - this looks like a claim frame, but is useless. eth src %pM on vid %d ...(hw_src %pM, hw_dst %pM)\n",
		   __func__, ethhdr->h_source, batadv_print_vid(vid), hw_src,
		   hw_dst);
	return true;
}

/**
 * batadv_bla_purge_backbone_gw() - Remove backbone gateways after a timeout or
 *  immediately
 * @bat_priv: the bat priv with all the mesh interface information
 * @now: whether the whole hash shall be wiped now
 *
 * Check when we last heard from other nodes, and remove them in case of
 * a time out, or clean all backbone gws if now is set.
 */
static void batadv_bla_purge_backbone_gw(struct batadv_priv *bat_priv, int now)
{
	spinlock_t *list_lock;	/* protects write access to the hash lists */
	struct batadv_bla_backbone_gw *backbone_gw;
	struct batadv_hashtable *hash;
	struct hlist_node *node_tmp;
	struct hlist_head *head;
	bool purged;
	int i;

	hash = bat_priv->bla.backbone_hash;
	if (!hash)
		return;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];
		list_lock = &hash->list_locks[i];

		do {
			purged = false;

			spin_lock_bh(list_lock);
			hlist_for_each_entry_safe(backbone_gw, node_tmp,
						  head, hash_entry) {
				if (now)
					goto purge_now;
				if (!batadv_has_timed_out(READ_ONCE(backbone_gw->lasttime),
							  BATADV_BLA_BACKBONE_TIMEOUT))
					continue;

				batadv_dbg(BATADV_DBG_BLA, backbone_gw->bat_priv,
					   "%s(): backbone gw %pM timed out\n",
					   __func__, backbone_gw->orig);

purge_now:
				purged = true;

				/* don't wait for the pending request anymore */
				spin_lock_bh(&bat_priv->bla.num_requests_lock);
				if (backbone_gw->state == BATADV_BLA_BACKBONE_GW_UNSYNCED)
					atomic_dec(&bat_priv->bla.num_requests);

				backbone_gw->state = BATADV_BLA_BACKBONE_GW_STOPPED;
				spin_unlock_bh(&bat_priv->bla.num_requests_lock);

				batadv_bla_del_backbone_claims(backbone_gw);

				hlist_del_rcu(&backbone_gw->hash_entry);
				break;
			}
			spin_unlock_bh(list_lock);

			if (purged) {
				/* reference for pending report_work */
				if (disable_work_sync(&backbone_gw->report_work))
					batadv_backbone_gw_put(backbone_gw);

				/* reference for hash_entry */
				batadv_backbone_gw_put(backbone_gw);
			}
		} while (purged);
	}
}

/**
 * batadv_bla_purge_claims() - Remove claims after a timeout or immediately
 * @bat_priv: the bat priv with all the mesh interface information
 * @primary_if: the selected primary interface, may be NULL if now is set
 * @now: whether the whole hash shall be wiped now
 *
 * Check when we heard last time from our own claims, and remove them in case of
 * a time out, or clean all claims if now is set
 */
static void batadv_bla_purge_claims(struct batadv_priv *bat_priv,
				    struct batadv_hard_iface *primary_if,
				    int now)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	struct batadv_bla_claim *claim;
	struct batadv_hashtable *hash;
	struct hlist_head *head;
	int i;

	hash = bat_priv->bla.claim_hash;
	if (!hash)
		return;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(claim, head, hash_entry) {
			/* only purge claims not currently in the process of being released.
			 * Such claims could otherwise have a NULL-ptr backbone_gw set because
			 * they already went through batadv_claim_release()
			 */
			if (!kref_get_unless_zero(&claim->refcount))
				continue;

			backbone_gw = batadv_bla_claim_get_backbone_gw(claim);
			if (now)
				goto purge_now;

			if (!batadv_compare_eth(backbone_gw->orig,
						primary_if->net_dev->dev_addr))
				goto skip;

			if (!batadv_has_timed_out(READ_ONCE(claim->lasttime),
						  BATADV_BLA_CLAIM_TIMEOUT))
				goto skip;

			batadv_dbg(BATADV_DBG_BLA, bat_priv,
				   "%s(): timed out.\n", __func__);

purge_now:
			batadv_dbg(BATADV_DBG_BLA, bat_priv,
				   "%s(): %pM, vid %d\n", __func__,
				   claim->addr, claim->vid);

			batadv_handle_unclaim(bat_priv, primary_if,
					      backbone_gw->orig,
					      claim->addr, claim->vid);
skip:
			batadv_backbone_gw_put(backbone_gw);
			batadv_claim_put(claim);
		}
		rcu_read_unlock();
	}
}

/**
 * batadv_bla_update_orig_address() - Update the backbone gateways when the own
 *  originator address changes
 * @bat_priv: the bat priv with all the mesh interface information
 * @primary_if: the new selected primary_if
 * @oldif: the old primary interface, may be NULL
 */
void batadv_bla_update_orig_address(struct batadv_priv *bat_priv,
				    struct batadv_hard_iface *primary_if,
				    struct batadv_hard_iface *oldif)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	struct batadv_hashtable *hash;
	struct hlist_head *head;
	__be16 group;
	int i;

	/* reset bridge loop avoidance group id */
	group = htons(crc16(0, primary_if->net_dev->dev_addr, ETH_ALEN));
	bat_priv->bla.claim_dest.group = group;

	/* purge everything when bridge loop avoidance is turned off */
	if (!READ_ONCE(bat_priv->bridge_loop_avoidance))
		oldif = NULL;

	if (!oldif) {
		batadv_bla_purge_claims(bat_priv, NULL, 1);
		batadv_bla_purge_backbone_gw(bat_priv, 1);
		return;
	}

	hash = bat_priv->bla.backbone_hash;
	if (!hash)
		return;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
			/* own orig still holds the old value. */
			if (!batadv_compare_eth(backbone_gw->orig,
						oldif->net_dev->dev_addr))
				continue;

			ether_addr_copy(backbone_gw->orig,
					primary_if->net_dev->dev_addr);
			/* send an announce frame so others will ask for our
			 * claims and update their tables.
			 */
			batadv_bla_send_announce(bat_priv, backbone_gw);
		}
		rcu_read_unlock();
	}
}

/**
 * batadv_bla_send_loopdetect() - send a loopdetect frame
 * @bat_priv: the bat priv with all the mesh interface information
 * @backbone_gw: the backbone gateway for which a loop should be detected
 *
 * To detect loops that the bridge loop avoidance can't handle, send a loop
 * detection packet on the backbone. Unlike other BLA frames, this frame will
 * be allowed on the mesh by other nodes. If it is received on the mesh, this
 * indicates that there is a loop.
 */
static void
batadv_bla_send_loopdetect(struct batadv_priv *bat_priv,
			   struct batadv_bla_backbone_gw *backbone_gw)
{
	batadv_dbg(BATADV_DBG_BLA, bat_priv, "Send loopdetect frame for vid %d\n",
		   backbone_gw->vid);
	batadv_bla_send_claim(bat_priv, bat_priv->bla.loopdetect_addr,
			      backbone_gw->vid, BATADV_CLAIM_TYPE_LOOPDETECT);
}

/**
 * batadv_bla_status_update() - purge bla interfaces if necessary
 * @net_dev: the mesh interface net device
 */
void batadv_bla_status_update(struct net_device *net_dev)
{
	struct batadv_priv *bat_priv = netdev_priv(net_dev);
	struct batadv_hard_iface *primary_if;

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if)
		return;

	/* this function already purges everything when bla is disabled,
	 * so just call that one.
	 */
	batadv_bla_update_orig_address(bat_priv, primary_if, primary_if);
	batadv_hardif_put(primary_if);
}

/**
 * batadv_bla_periodic_work() - performs periodic bla work
 * @work: kernel work struct
 *
 * periodic work to do:
 *  * purge structures when they are too old
 *  * send announcements
 */
static void batadv_bla_periodic_work(struct work_struct *work)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	struct batadv_hard_iface *primary_if;
	struct delayed_work *delayed_work;
	struct batadv_priv_bla *priv_bla;
	struct batadv_hashtable *hash;
	struct batadv_priv *bat_priv;
	bool send_loopdetect = false;
	struct hlist_head *head;
	int i;

	delayed_work = to_delayed_work(work);
	priv_bla = container_of(delayed_work, struct batadv_priv_bla, work);
	bat_priv = container_of(priv_bla, struct batadv_priv, bla);
	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if)
		goto out;

	batadv_bla_purge_claims(bat_priv, primary_if, 0);
	batadv_bla_purge_backbone_gw(bat_priv, 0);

	if (!READ_ONCE(bat_priv->bridge_loop_avoidance))
		goto out;

	if (atomic_dec_and_test(&bat_priv->bla.loopdetect_next)) {
		/* set a new random mac address for the next bridge loop
		 * detection frames. Set the locally administered bit to avoid
		 * collisions with users mac addresses.
		 */
		eth_random_addr(bat_priv->bla.loopdetect_addr);
		bat_priv->bla.loopdetect_addr[0] = 0xba;
		bat_priv->bla.loopdetect_addr[1] = 0xbe;
		WRITE_ONCE(bat_priv->bla.loopdetect_lasttime, jiffies);
		atomic_set(&bat_priv->bla.loopdetect_next,
			   BATADV_BLA_LOOPDETECT_PERIODS);

		/* mark for sending loop detect on all VLANs */
		send_loopdetect = true;
	}

	hash = bat_priv->bla.backbone_hash;
	if (!hash)
		goto out;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
			if (!batadv_compare_eth(backbone_gw->orig,
						primary_if->net_dev->dev_addr))
				continue;

			WRITE_ONCE(backbone_gw->lasttime, jiffies);

			batadv_bla_send_announce(bat_priv, backbone_gw);
			if (send_loopdetect)
				batadv_bla_send_loopdetect(bat_priv,
							   backbone_gw);

			/* state is only set to unsynced after creation to avoid
			 * problems when we are not yet known as backbone gw
			 * in the backbone.
			 *
			 * We can reset this now after we waited some periods
			 * to give bridge forward delays and bla group forming
			 * some grace time.
			 */

			spin_lock_bh(&bat_priv->bla.num_requests_lock);
			if (backbone_gw->state != BATADV_BLA_BACKBONE_GW_UNSYNCED)
				goto unlock_next;

			if (backbone_gw->wait_periods > 0)
				backbone_gw->wait_periods--;

			if (backbone_gw->wait_periods > 0)
				goto unlock_next;

			backbone_gw->state = BATADV_BLA_BACKBONE_GW_SYNCED;
			atomic_dec(&backbone_gw->bat_priv->bla.num_requests);

unlock_next:
			spin_unlock_bh(&bat_priv->bla.num_requests_lock);
		}
		rcu_read_unlock();
	}
out:
	batadv_hardif_put(primary_if);

	queue_delayed_work(batadv_event_workqueue, &bat_priv->bla.work,
			   msecs_to_jiffies(BATADV_BLA_PERIOD_LENGTH));
}

/* The hash for claim and backbone hash receive the same key because they
 * are getting initialized by hash_new with the same key. Reinitializing
 * them with to different keys to allow nested locking without generating
 * lockdep warnings
 */
static struct lock_class_key batadv_claim_hash_lock_class_key;
static struct lock_class_key batadv_backbone_hash_lock_class_key;

/**
 * batadv_bla_init() - initialize all bla structures
 * @bat_priv: the bat priv with all the mesh interface information
 *
 * Return: 0 on success, < 0 on error.
 */
int batadv_bla_init(struct batadv_priv *bat_priv)
{
	static const u8 claim_dest[ETH_ALEN] __aligned(2) = {
		0xff, 0x43, 0x05, 0x00, 0x00, 0x00
	};
	struct batadv_hard_iface *primary_if;
	unsigned long entrytime;
	u16 crc;
	int i;

	spin_lock_init(&bat_priv->bla.bcast_duplist_lock);

	batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla hash registering\n");

	/* setting claim destination address */
	memcpy(&bat_priv->bla.claim_dest.magic, claim_dest, 3);
	bat_priv->bla.claim_dest.type = 0;
	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (primary_if) {
		crc = crc16(0, primary_if->net_dev->dev_addr, ETH_ALEN);
		bat_priv->bla.claim_dest.group = htons(crc);
		batadv_hardif_put(primary_if);
	} else {
		bat_priv->bla.claim_dest.group = 0; /* will be set later */
	}

	/* initialize the duplicate list */
	entrytime = jiffies - msecs_to_jiffies(BATADV_DUPLIST_TIMEOUT);
	for (i = 0; i < BATADV_DUPLIST_SIZE; i++)
		bat_priv->bla.bcast_duplist[i].entrytime = entrytime;
	bat_priv->bla.bcast_duplist_curr = 0;

	atomic_set(&bat_priv->bla.loopdetect_next,
		   BATADV_BLA_LOOPDETECT_PERIODS);

	if (bat_priv->bla.claim_hash)
		return 0;

	bat_priv->bla.claim_hash = batadv_hash_new(128);
	if (!bat_priv->bla.claim_hash)
		return -ENOMEM;

	bat_priv->bla.backbone_hash = batadv_hash_new(32);
	if (!bat_priv->bla.backbone_hash) {
		batadv_hash_destroy(bat_priv->bla.claim_hash);
		bat_priv->bla.claim_hash = NULL;
		return -ENOMEM;
	}

	batadv_hash_set_lock_class(bat_priv->bla.claim_hash,
				   &batadv_claim_hash_lock_class_key);
	batadv_hash_set_lock_class(bat_priv->bla.backbone_hash,
				   &batadv_backbone_hash_lock_class_key);

	batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla hashes initialized\n");

	INIT_DELAYED_WORK(&bat_priv->bla.work, batadv_bla_periodic_work);

	queue_delayed_work(batadv_event_workqueue, &bat_priv->bla.work,
			   msecs_to_jiffies(BATADV_BLA_PERIOD_LENGTH));
	return 0;
}

/**
 * batadv_bla_check_duplist() - Check if a frame is in the broadcast dup.
 * @bat_priv: the bat priv with all the mesh interface information
 * @skb: contains the multicast packet to be checked
 * @payload_offset: offset in the skb, marking the start of the data to be CRC'ed
 * @orig: originator mac address, NULL if unknown
 *
 * Check if it is on our broadcast list. Another gateway might have sent the
 * same packet because it is connected to the same backbone, so we have to
 * remove this duplicate.
 *
 * This is performed by checking the CRC, which will tell us
 * with a good chance that it is the same packet. If it is furthermore
 * sent by another host, drop it. We allow equal packets from
 * the same host however as this might be intended.
 *
 * Return: true if a packet is in the duplicate list, false otherwise.
 */
static bool batadv_bla_check_duplist(struct batadv_priv *bat_priv,
				     struct sk_buff *skb, int payload_offset,
				     const u8 *orig)
{
	struct batadv_bcast_duplist_entry *entry;
	bool ret = false;
	int payload_len;
	int curr;
	u32 crc;
	int i;

	/* calculate the crc ... */
	payload_len = skb->len - payload_offset;
	crc = skb_crc32c(skb, payload_offset, payload_len, 0);

	spin_lock_bh(&bat_priv->bla.bcast_duplist_lock);

	for (i = 0; i < BATADV_DUPLIST_SIZE; i++) {
		curr = (bat_priv->bla.bcast_duplist_curr + i);
		curr %= BATADV_DUPLIST_SIZE;
		entry = &bat_priv->bla.bcast_duplist[curr];

		/* we can stop searching if the entry is too old ;
		 * later entries will be even older
		 */
		if (batadv_has_timed_out(entry->entrytime,
					 BATADV_DUPLIST_TIMEOUT))
			break;

		if (entry->crc != crc)
			continue;

		/* are the originators both known and not anonymous? */
		if (orig && !is_zero_ether_addr(orig) &&
		    !is_zero_ether_addr(entry->orig)) {
			/* If known, check if the new frame came from
			 * the same originator:
			 * We are safe to take identical frames from the
			 * same orig, if known, as multiplications in
			 * the mesh are detected via the (orig, seqno) pair.
			 * So we can be a bit more liberal here and allow
			 * identical frames from the same orig which the source
			 * host might have sent multiple times on purpose.
			 */
			if (batadv_compare_eth(entry->orig, orig))
				continue;
		}

		/* this entry seems to match: same crc, not too old,
		 * and from another gw. therefore return true to forbid it.
		 */
		ret = true;
		goto out;
	}
	/* not found, add a new entry (overwrite the oldest entry)
	 * and allow it, its the first occurrence.
	 */
	curr = (bat_priv->bla.bcast_duplist_curr + BATADV_DUPLIST_SIZE - 1);
	curr %= BATADV_DUPLIST_SIZE;
	entry = &bat_priv->bla.bcast_duplist[curr];
	entry->crc = crc;
	entry->entrytime = jiffies;

	/* known originator */
	if (orig)
		ether_addr_copy(entry->orig, orig);
	/* anonymous originator */
	else
		eth_zero_addr(entry->orig);

	bat_priv->bla.bcast_duplist_curr = curr;

out:
	spin_unlock_bh(&bat_priv->bla.bcast_duplist_lock);

	return ret;
}

/**
 * batadv_bla_check_ucast_duplist() - Check if a frame is in the broadcast dup.
 * @bat_priv: the bat priv with all the mesh interface information
 * @skb: contains the multicast packet to be checked, decapsulated from a
 *  unicast_packet
 *
 * Check if it is on our broadcast list. Another gateway might have sent the
 * same packet because it is connected to the same backbone, so we have to
 * remove this duplicate.
 *
 * Return: true if a packet is in the duplicate list, false otherwise.
 */
static bool batadv_bla_check_ucast_duplist(struct batadv_priv *bat_priv,
					   struct sk_buff *skb)
{
	return batadv_bla_check_duplist(bat_priv, skb, 0, NULL);
}

/**
 * batadv_bla_check_bcast_duplist() - Check if a frame is in the broadcast dup.
 * @bat_priv: the bat priv with all the mesh interface information
 * @skb: contains the bcast_packet to be checked
 *
 * Check if it is on our broadcast list. Another gateway might have sent the
 * same packet because it is connected to the same backbone, so we have to
 * remove this duplicate.
 *
 * Return: true if a packet is in the duplicate list, false otherwise.
 */
bool batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,
				    struct sk_buff *skb)
{
	struct batadv_bcast_packet *bcast_packet;

	bcast_packet = (struct batadv_bcast_packet *)skb->data;

	return batadv_bla_check_duplist(bat_priv, skb, sizeof(*bcast_packet),
					bcast_packet->orig);
}

/**
 * batadv_bla_is_backbone_gw_orig() - Check if the originator is a gateway for
 *  the VLAN identified by vid.
 * @bat_priv: the bat priv with all the mesh interface information
 * @orig: originator mac address
 * @vid: VLAN identifier
 *
 * Return: true if orig is a backbone for this vid, false otherwise.
 */
bool batadv_bla_is_backbone_gw_orig(struct batadv_priv *bat_priv, u8 *orig,
				    unsigned short vid)
{
	struct batadv_hashtable *hash = bat_priv->bla.backbone_hash;
	struct batadv_bla_backbone_gw *backbone_gw;
	struct hlist_head *head;
	int i;

	if (!READ_ONCE(bat_priv->bridge_loop_avoidance))
		return false;

	if (!hash)
		return false;

	for (i = 0; i < hash->size; i++) {
		head = &hash->table[i];

		rcu_read_lock();
		hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
			if (batadv_compare_eth(backbone_gw->orig, orig) &&
			    backbone_gw->vid == vid) {
				rcu_read_unlock();
				return true;
			}
		}
		rcu_read_unlock();
	}

	return false;
}

/**
 * batadv_bla_is_backbone_gw() - check if originator is a backbone gw for a VLAN
 * @skb: the frame to be checked
 * @orig_node: the orig_node of the frame
 * @hdr_size: maximum length of the frame
 *
 * Warning: This function may reallocate the skb data buffer via
 * pskb_may_pull()/batadv_get_vid()/... Any pointer into the skb data (e.g.
 * obtained from skb->data or eth_hdr()) before this call must be considered
 * invalid afterwards and has to be reacquired.
 *
 * Return: true if the orig_node is also a gateway on the mesh interface,
 * otherwise it returns false.
 */
bool batadv_bla_is_backbone_gw(struct sk_buff *skb,
			       struct batadv_orig_node *orig_node, int hdr_size)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	unsigned short vid;

	if (!READ_ONCE(orig_node->bat_priv->bridge_loop_avoidance))
		return false;

	/* first, find out the vid. */
	if (!pskb_may_pull(skb, hdr_size + ETH_HLEN))
		return false;

	vid = batadv_get_vid(skb, hdr_size);

	/* see if this originator is a backbone gw for this VLAN */
	backbone_gw = batadv_backbone_hash_find(orig_node->bat_priv,
						orig_node->orig, vid);
	if (!backbone_gw)
		return false;

	batadv_backbone_gw_put(backbone_gw);
	return true;
}

/**
 * batadv_bla_free() - free all bla structures
 * @bat_priv: the bat priv with all the mesh interface information
 *
 * for meshinterface free or module unload
 */
void batadv_bla_free(struct batadv_priv *bat_priv)
{
	struct batadv_hard_iface *primary_if;

	disable_delayed_work_sync(&bat_priv->bla.work);
	primary_if = batadv_primary_if_get_selected(bat_priv);

	if (bat_priv->bla.claim_hash) {
		batadv_bla_purge_claims(bat_priv, primary_if, 1);
		batadv_hash_destroy(bat_priv->bla.claim_hash);
		bat_priv->bla.claim_hash = NULL;
	}
	if (bat_priv->bla.backbone_hash) {
		batadv_bla_purge_backbone_gw(bat_priv, 1);
		batadv_hash_destroy(bat_priv->bla.backbone_hash);
		bat_priv->bla.backbone_hash = NULL;
	}
	batadv_hardif_put(primary_if);
}

/**
 * batadv_bla_loopdetect_check() - check and handle a detected loop
 * @bat_priv: the bat priv with all the mesh interface information
 * @skb: the packet to check
 * @primary_if: interface where the request came on
 * @vid: the VLAN ID of the frame
 *
 * Checks if this packet is a loop detect frame which has been sent by us,
 * throws an uevent and logs the event if that is the case.
 *
 * Return: true if it is a loop detect frame which is to be dropped, false
 * otherwise.
 */
static bool
batadv_bla_loopdetect_check(struct batadv_priv *bat_priv, struct sk_buff *skb,
			    struct batadv_hard_iface *primary_if,
			    unsigned short vid)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	struct ethhdr *ethhdr;
	bool ret;

	ethhdr = eth_hdr(skb);

	/* Only check for the MAC address and skip more checks here for
	 * performance reasons - this function is on the hotpath, after all.
	 */
	if (!batadv_compare_eth(ethhdr->h_source,
				bat_priv->bla.loopdetect_addr))
		return false;

	/* If the packet came too late, don't forward it on the mesh
	 * but don't consider that as loop. It might be a coincidence.
	 */
	if (batadv_has_timed_out(READ_ONCE(bat_priv->bla.loopdetect_lasttime),
				 BATADV_BLA_LOOPDETECT_TIMEOUT))
		return true;

	backbone_gw = batadv_bla_get_backbone_gw(bat_priv,
						 primary_if->net_dev->dev_addr,
						 vid, true);
	if (unlikely(!backbone_gw))
		return true;

	ret = queue_work(batadv_event_workqueue, &backbone_gw->report_work);

	/* backbone_gw is unreferenced in the report work function
	 * if queue_work() call was successful
	 */
	if (!ret)
		batadv_backbone_gw_put(backbone_gw);

	return true;
}

/**
 * batadv_bla_rx() - check packets coming from the mesh.
 * @bat_priv: the bat priv with all the mesh interface information
 * @skb: the frame to be checked
 * @vid: the VLAN ID of the frame
 * @packet_type: the batman packet type this frame came in
 *
 * batadv_bla_rx avoidance checks if:
 *  * we have to race for a claim
 *  * if the frame is allowed on the LAN
 *
 * In these cases, the skb is further handled by this function
 *
 * Return: true if handled, otherwise it returns false and the caller shall
 * further process the skb.
 */
bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
		   unsigned short vid, int packet_type)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	struct batadv_bla_claim *claim = NULL;
	struct batadv_bla_claim search_claim;
	struct batadv_hard_iface *primary_if;
	struct ethhdr *ethhdr;
	bool own_claim;
	bool ret;

	ethhdr = eth_hdr(skb);

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if)
		goto handled;

	if (!READ_ONCE(bat_priv->bridge_loop_avoidance))
		goto allow;

	if (batadv_bla_loopdetect_check(bat_priv, skb, primary_if, vid))
		goto handled;

	if (unlikely(atomic_read(&bat_priv->bla.num_requests)))
		/* don't allow multicast packets while requests are in flight */
		if (is_multicast_ether_addr(ethhdr->h_dest))
			/* Both broadcast flooding or multicast-via-unicasts
			 * delivery might send to multiple backbone gateways
			 * sharing the same LAN and therefore need to coordinate
			 * which backbone gateway forwards into the LAN,
			 * by claiming the payload source address.
			 *
			 * Broadcast flooding and multicast-via-unicasts
			 * delivery use the following two batman packet types.
			 * Note: explicitly exclude BATADV_UNICAST_4ADDR,
			 * as the DHCP gateway feature will send explicitly
			 * to only one BLA gateway, so the claiming process
			 * should be avoided there.
			 */
			if (packet_type == BATADV_BCAST ||
			    packet_type == BATADV_UNICAST)
				goto handled;

	/* potential duplicates from foreign BLA backbone gateways via
	 * multicast-in-unicast packets
	 */
	if (is_multicast_ether_addr(ethhdr->h_dest) &&
	    packet_type == BATADV_UNICAST &&
	    batadv_bla_check_ucast_duplist(bat_priv, skb))
		goto handled;

	ether_addr_copy(search_claim.addr, ethhdr->h_source);
	search_claim.vid = vid;
	claim = batadv_claim_hash_find(bat_priv, &search_claim);

	if (!claim) {
		bool local = batadv_is_my_client(bat_priv, ethhdr->h_source, vid);

		/* possible optimization: race for a claim */
		/* No claim exists yet, claim it for us!
		 */

		batadv_dbg(BATADV_DBG_BLA, bat_priv,
			   "%s(): Unclaimed MAC %pM found. Claim it. Local: %s\n",
			   __func__, ethhdr->h_source, str_yes_no(local));
		batadv_handle_claim(bat_priv, primary_if,
				    primary_if->net_dev->dev_addr,
				    ethhdr->h_source, vid);
		goto allow;
	}

	/* if it is our own claim ... */
	backbone_gw = batadv_bla_claim_get_backbone_gw(claim);
	own_claim = batadv_compare_eth(backbone_gw->orig,
				       primary_if->net_dev->dev_addr);
	batadv_backbone_gw_put(backbone_gw);

	if (own_claim) {
		/* ... allow it in any case */
		WRITE_ONCE(claim->lasttime, jiffies);
		goto allow;
	}

	/* if it is a multicast ... */
	if (is_multicast_ether_addr(ethhdr->h_dest) &&
	    (packet_type == BATADV_BCAST || packet_type == BATADV_UNICAST)) {
		/* ... drop it. the responsible gateway is in charge.
		 *
		 * We need to check packet type because with the gateway
		 * feature, broadcasts (like DHCP requests) may be sent
		 * using a unicast 4 address packet type. See comment above.
		 */
		goto handled;
	} else {
		/* seems the client considers us as its best gateway.
		 * send a claim and update the claim table
		 * immediately.
		 */
		batadv_handle_claim(bat_priv, primary_if,
				    primary_if->net_dev->dev_addr,
				    ethhdr->h_source, vid);
		goto allow;
	}
allow:
	batadv_bla_update_own_backbone_gw(bat_priv, primary_if, vid);
	ret = false;
	goto out;

handled:
	kfree_skb(skb);
	ret = true;

out:
	batadv_hardif_put(primary_if);
	batadv_claim_put(claim);
	return ret;
}

/**
 * batadv_bla_tx() - check packets going into the mesh
 * @bat_priv: the bat priv with all the mesh interface information
 * @skb: the frame to be checked
 * @vid: the VLAN ID of the frame
 *
 * batadv_bla_tx checks if:
 *  * a claim was received which has to be processed
 *  * the frame is allowed on the mesh
 *
 * in these cases, the skb is further handled by this function.
 *
 * Warning: This function may reallocate the skb data buffer via
 * batadv_bla_process_claim()/... Any pointer into the skb data (e.g.
 * obtained from skb->data or eth_hdr()) before this call must be considered
 * invalid afterwards and has to be reacquired.
 *
 * Return: true if handled, otherwise it returns false and the caller shall
 * further process the skb.
 */
bool batadv_bla_tx(struct batadv_priv *bat_priv, struct sk_buff *skb,
		   unsigned short vid)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	struct batadv_bla_claim *claim = NULL;
	struct batadv_bla_claim search_claim;
	struct batadv_hard_iface *primary_if;
	struct ethhdr *ethhdr;
	bool client_roamed;
	bool ret = false;

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if)
		goto out;

	if (!READ_ONCE(bat_priv->bridge_loop_avoidance))
		goto allow;

	if (batadv_bla_process_claim(bat_priv, primary_if, skb))
		goto handled;

	ethhdr = eth_hdr(skb);

	if (unlikely(atomic_read(&bat_priv->bla.num_requests)))
		/* don't allow broadcasts while requests are in flight */
		if (is_multicast_ether_addr(ethhdr->h_dest))
			goto handled;

	ether_addr_copy(search_claim.addr, ethhdr->h_source);
	search_claim.vid = vid;

	claim = batadv_claim_hash_find(bat_priv, &search_claim);

	/* if no claim exists, allow it. */
	if (!claim)
		goto allow;

	/* check if we are responsible. */
	backbone_gw = batadv_bla_claim_get_backbone_gw(claim);
	client_roamed = batadv_compare_eth(backbone_gw->orig,
					   primary_if->net_dev->dev_addr);
	batadv_backbone_gw_put(backbone_gw);

	if (client_roamed) {
		/* if yes, the client has roamed and we have
		 * to unclaim it.
		 */
		if (batadv_has_timed_out(READ_ONCE(claim->lasttime), 100)) {
			/* only unclaim if the last claim entry is
			 * older than 100 ms to make sure we really
			 * have a roaming client here.
			 */
			batadv_dbg(BATADV_DBG_BLA, bat_priv, "%s(): Roaming client %pM detected. Unclaim it.\n",
				   __func__, ethhdr->h_source);
			batadv_handle_unclaim(bat_priv, primary_if,
					      primary_if->net_dev->dev_addr,
					      ethhdr->h_source, vid);
			goto allow;
		} else {
			batadv_dbg(BATADV_DBG_BLA, bat_priv, "%s(): Race for claim %pM detected. Drop packet.\n",
				   __func__, ethhdr->h_source);
			goto handled;
		}
	}

	/* check if it is a multicast/broadcast frame */
	if (is_multicast_ether_addr(ethhdr->h_dest)) {
		/* drop it. the responsible gateway has forwarded it into
		 * the backbone network.
		 */
		goto handled;
	} else {
		/* we must allow it. at least if we are
		 * responsible for the DESTINATION.
		 */
		goto allow;
	}
allow:
	batadv_bla_update_own_backbone_gw(bat_priv, primary_if, vid);
	ret = false;
	goto out;
handled:
	ret = true;
out:
	batadv_hardif_put(primary_if);
	batadv_claim_put(claim);
	return ret;
}

/**
 * batadv_bla_claim_dump_entry() - dump one entry of the claim table
 * to a netlink socket
 * @msg: buffer for the message
 * @portid: netlink port
 * @cb: Control block containing additional options
 * @primary_if: primary interface
 * @claim: entry to dump
 *
 * Return: 0 or error code.
 */
static int
batadv_bla_claim_dump_entry(struct sk_buff *msg, u32 portid,
			    struct netlink_callback *cb,
			    struct batadv_hard_iface *primary_if,
			    struct batadv_bla_claim *claim)
{
	const u8 *primary_addr = primary_if->net_dev->dev_addr;
	struct batadv_bla_backbone_gw *backbone_gw;
	int ret = -EINVAL;
	u16 backbone_crc;
	bool is_own;
	void *hdr;

	hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
			  &batadv_netlink_family, NLM_F_MULTI,
			  BATADV_CMD_GET_BLA_CLAIM);
	if (!hdr) {
		ret = -ENOBUFS;
		goto out;
	}

	genl_dump_check_consistent(cb, hdr);

	backbone_gw = batadv_bla_claim_get_backbone_gw(claim);

	is_own = batadv_compare_eth(backbone_gw->orig, primary_addr);

	spin_lock_bh(&backbone_gw->crc_lock);
	backbone_crc = backbone_gw->crc;
	spin_unlock_bh(&backbone_gw->crc_lock);

	if (is_own)
		if (nla_put_flag(msg, BATADV_ATTR_BLA_OWN)) {
			genlmsg_cancel(msg, hdr);
			goto put_backbone_gw;
		}

	if (nla_put(msg, BATADV_ATTR_BLA_ADDRESS, ETH_ALEN, claim->addr) ||
	    nla_put_u16(msg, BATADV_ATTR_BLA_VID, claim->vid) ||
	    nla_put(msg, BATADV_ATTR_BLA_BACKBONE, ETH_ALEN,
		    backbone_gw->orig) ||
	    nla_put_u16(msg, BATADV_ATTR_BLA_CRC,
			backbone_crc)) {
		genlmsg_cancel(msg, hdr);
		goto put_backbone_gw;
	}

	genlmsg_end(msg, hdr);
	ret = 0;

put_backbone_gw:
	batadv_backbone_gw_put(backbone_gw);
out:
	return ret;
}

/**
 * batadv_bla_claim_dump_bucket() - dump one bucket of the claim table
 * to a netlink socket
 * @msg: buffer for the message
 * @portid: netlink port
 * @cb: Control block containing additional options
 * @primary_if: primary interface
 * @hash: hash to dump
 * @bucket: bucket index to dump
 * @idx_skip: How many entries to skip
 *
 * Return: always 0.
 */
static int
batadv_bla_claim_dump_bucket(struct sk_buff *msg, u32 portid,
			     struct netlink_callback *cb,
			     struct batadv_hard_iface *primary_if,
			     struct batadv_hashtable *hash, unsigned int bucket,
			     int *idx_skip)
{
	struct batadv_bla_claim *claim;
	int idx = 0;
	int ret = 0;

	spin_lock_bh(&hash->list_locks[bucket]);
	cb->seq = atomic_read(&hash->generation) << 1 | 1;

	hlist_for_each_entry(claim, &hash->table[bucket], hash_entry) {
		if (idx++ < *idx_skip)
			continue;

		ret = batadv_bla_claim_dump_entry(msg, portid, cb,
						  primary_if, claim);
		if (ret) {
			*idx_skip = idx - 1;
			goto unlock;
		}
	}

	*idx_skip = 0;
unlock:
	spin_unlock_bh(&hash->list_locks[bucket]);
	return ret;
}

/**
 * batadv_bla_claim_dump() - dump claim table to a netlink socket
 * @msg: buffer for the message
 * @cb: callback structure containing arguments
 *
 * Return: message length.
 */
int batadv_bla_claim_dump(struct sk_buff *msg, struct netlink_callback *cb)
{
	struct batadv_hard_iface *primary_if = NULL;
	int portid = NETLINK_CB(cb->skb).portid;
	struct net_device *mesh_iface;
	struct batadv_hashtable *hash;
	struct batadv_priv *bat_priv;
	int bucket = cb->args[0];
	int idx = cb->args[1];
	int ret = 0;

	mesh_iface = batadv_netlink_get_meshif(cb);
	if (IS_ERR(mesh_iface))
		return PTR_ERR(mesh_iface);

	bat_priv = netdev_priv(mesh_iface);
	hash = bat_priv->bla.claim_hash;

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
		ret = -ENOENT;
		goto out;
	}

	while (bucket < hash->size) {
		if (batadv_bla_claim_dump_bucket(msg, portid, cb, primary_if,
						 hash, bucket, &idx))
			break;
		bucket++;
	}

	cb->args[0] = bucket;
	cb->args[1] = idx;

	ret = msg->len;

out:
	batadv_hardif_put(primary_if);

	dev_put(mesh_iface);

	return ret;
}

/**
 * batadv_bla_backbone_dump_entry() - dump one entry of the backbone table to a
 *  netlink socket
 * @msg: buffer for the message
 * @portid: netlink port
 * @cb: Control block containing additional options
 * @primary_if: primary interface
 * @backbone_gw: entry to dump
 *
 * Return: 0 or error code.
 */
static int
batadv_bla_backbone_dump_entry(struct sk_buff *msg, u32 portid,
			       struct netlink_callback *cb,
			       struct batadv_hard_iface *primary_if,
			       struct batadv_bla_backbone_gw *backbone_gw)
{
	const u8 *primary_addr = primary_if->net_dev->dev_addr;
	int ret = -EINVAL;
	u16 backbone_crc;
	bool is_own;
	int msecs;
	void *hdr;

	hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
			  &batadv_netlink_family, NLM_F_MULTI,
			  BATADV_CMD_GET_BLA_BACKBONE);
	if (!hdr) {
		ret = -ENOBUFS;
		goto out;
	}

	genl_dump_check_consistent(cb, hdr);

	is_own = batadv_compare_eth(backbone_gw->orig, primary_addr);

	spin_lock_bh(&backbone_gw->crc_lock);
	backbone_crc = backbone_gw->crc;
	spin_unlock_bh(&backbone_gw->crc_lock);

	msecs = jiffies_to_msecs(jiffies - READ_ONCE(backbone_gw->lasttime));

	if (is_own)
		if (nla_put_flag(msg, BATADV_ATTR_BLA_OWN)) {
			genlmsg_cancel(msg, hdr);
			goto out;
		}

	if (nla_put(msg, BATADV_ATTR_BLA_BACKBONE, ETH_ALEN,
		    backbone_gw->orig) ||
	    nla_put_u16(msg, BATADV_ATTR_BLA_VID, backbone_gw->vid) ||
	    nla_put_u16(msg, BATADV_ATTR_BLA_CRC,
			backbone_crc) ||
	    nla_put_u32(msg, BATADV_ATTR_LAST_SEEN_MSECS, msecs)) {
		genlmsg_cancel(msg, hdr);
		goto out;
	}

	genlmsg_end(msg, hdr);
	ret = 0;

out:
	return ret;
}

/**
 * batadv_bla_backbone_dump_bucket() - dump one bucket of the backbone table to
 *  a netlink socket
 * @msg: buffer for the message
 * @portid: netlink port
 * @cb: Control block containing additional options
 * @primary_if: primary interface
 * @hash: hash to dump
 * @bucket: bucket index to dump
 * @idx_skip: How many entries to skip
 *
 * Return: always 0.
 */
static int
batadv_bla_backbone_dump_bucket(struct sk_buff *msg, u32 portid,
				struct netlink_callback *cb,
				struct batadv_hard_iface *primary_if,
				struct batadv_hashtable *hash,
				unsigned int bucket, int *idx_skip)
{
	struct batadv_bla_backbone_gw *backbone_gw;
	int idx = 0;
	int ret = 0;

	spin_lock_bh(&hash->list_locks[bucket]);
	cb->seq = atomic_read(&hash->generation) << 1 | 1;

	hlist_for_each_entry(backbone_gw, &hash->table[bucket], hash_entry) {
		if (idx++ < *idx_skip)
			continue;

		ret = batadv_bla_backbone_dump_entry(msg, portid, cb,
						     primary_if, backbone_gw);
		if (ret) {
			*idx_skip = idx - 1;
			goto unlock;
		}
	}

	*idx_skip = 0;
unlock:
	spin_unlock_bh(&hash->list_locks[bucket]);
	return ret;
}

/**
 * batadv_bla_backbone_dump() - dump backbone table to a netlink socket
 * @msg: buffer for the message
 * @cb: callback structure containing arguments
 *
 * Return: message length.
 */
int batadv_bla_backbone_dump(struct sk_buff *msg, struct netlink_callback *cb)
{
	struct batadv_hard_iface *primary_if = NULL;
	int portid = NETLINK_CB(cb->skb).portid;
	struct net_device *mesh_iface;
	struct batadv_hashtable *hash;
	struct batadv_priv *bat_priv;
	int bucket = cb->args[0];
	int idx = cb->args[1];
	int ret = 0;

	mesh_iface = batadv_netlink_get_meshif(cb);
	if (IS_ERR(mesh_iface))
		return PTR_ERR(mesh_iface);

	bat_priv = netdev_priv(mesh_iface);
	hash = bat_priv->bla.backbone_hash;

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
		ret = -ENOENT;
		goto out;
	}

	while (bucket < hash->size) {
		if (batadv_bla_backbone_dump_bucket(msg, portid, cb, primary_if,
						    hash, bucket, &idx))
			break;
		bucket++;
	}

	cb->args[0] = bucket;
	cb->args[1] = idx;

	ret = msg->len;

out:
	batadv_hardif_put(primary_if);

	dev_put(mesh_iface);

	return ret;
}

#ifdef CONFIG_BATMAN_ADV_DAT
/**
 * batadv_bla_check_claim() - check if address is claimed
 *
 * @bat_priv: the bat priv with all the mesh interface information
 * @addr: mac address of which the claim status is checked
 * @vid: the VLAN ID
 *
 * addr is checked if this address is claimed by the local device itself.
 *
 * Return: true if bla is disabled or the mac is claimed by the device,
 * false if the device addr is already claimed by another gateway
 */
bool batadv_bla_check_claim(struct batadv_priv *bat_priv,
			    u8 *addr, unsigned short vid)
{
	struct batadv_hard_iface *primary_if = NULL;
	struct batadv_bla_backbone_gw *backbone_gw;
	struct batadv_bla_claim *claim = NULL;
	struct batadv_bla_claim search_claim;
	bool ret = true;

	if (!READ_ONCE(bat_priv->bridge_loop_avoidance))
		return ret;

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if)
		return ret;

	/* First look if the mac address is claimed */
	ether_addr_copy(search_claim.addr, addr);
	search_claim.vid = vid;

	claim = batadv_claim_hash_find(bat_priv, &search_claim);

	/* If there is a claim and we are not owner of the claim,
	 * return false.
	 */
	if (claim) {
		backbone_gw = batadv_bla_claim_get_backbone_gw(claim);

		if (!batadv_compare_eth(backbone_gw->orig,
					primary_if->net_dev->dev_addr))
			ret = false;

		batadv_backbone_gw_put(backbone_gw);
		batadv_claim_put(claim);
	}

	batadv_hardif_put(primary_if);
	return ret;
}
#endif