net/mac80211/mesh.c

/*
 * Copyright (c) 2008, 2009 open80211s Ltd.
 * Authors:    Luis Carlos Cobo <luisca@cozybit.com>
 * 	       Javier Cardona <javier@cozybit.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/slab.h>
#include <asm/unaligned.h>
#include "ieee80211_i.h"
#include "mesh.h"

#define TMR_RUNNING_HK	0
#define TMR_RUNNING_MP	1
#define TMR_RUNNING_MPR	2

static int mesh_allocated;
static struct kmem_cache *rm_cache;

bool mesh_action_is_path_sel(struct ieee80211_mgmt *mgmt)
{
	return (mgmt->u.action.u.mesh_action.action_code ==
			WLAN_MESH_ACTION_HWMP_PATH_SELECTION);
}

void ieee80211s_init(void)
{
	mesh_pathtbl_init();
	mesh_allocated = 1;
	rm_cache = kmem_cache_create("mesh_rmc", sizeof(struct rmc_entry),
				     0, 0, NULL);
}

void ieee80211s_stop(void)
{
	if (!mesh_allocated)
		return;
	mesh_pathtbl_unregister();
	kmem_cache_destroy(rm_cache);
}

static void ieee80211_mesh_housekeeping_timer(unsigned long data)
{
	struct ieee80211_sub_if_data *sdata = (void *) data;
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;

	set_bit(MESH_WORK_HOUSEKEEPING, &ifmsh->wrkq_flags);

	if (local->quiescing) {
		set_bit(TMR_RUNNING_HK, &ifmsh->timers_running);
		return;
	}

	ieee80211_queue_work(&local->hw, &sdata->work);
}

/**
 * mesh_matches_local - check if the config of a mesh point matches ours
 *
 * @sdata: local mesh subif
 * @ie: information elements of a management frame from the mesh peer
 *
 * This function checks if the mesh configuration of a mesh point matches the
 * local mesh configuration, i.e. if both nodes belong to the same mesh network.
 */
bool mesh_matches_local(struct ieee80211_sub_if_data *sdata,
			struct ieee802_11_elems *ie)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct ieee80211_local *local = sdata->local;
	u32 basic_rates = 0;
	struct cfg80211_chan_def sta_chan_def;

	/*
	 * As support for each feature is added, check for matching
	 * - On mesh config capabilities
	 *   - Power Save Support En
	 *   - Sync support enabled
	 *   - Sync support active
	 *   - Sync support required from peer
	 *   - MDA enabled
	 * - Power management control on fc
	 */
	if (!(ifmsh->mesh_id_len == ie->mesh_id_len &&
	     memcmp(ifmsh->mesh_id, ie->mesh_id, ie->mesh_id_len) == 0 &&
	     (ifmsh->mesh_pp_id == ie->mesh_config->meshconf_psel) &&
	     (ifmsh->mesh_pm_id == ie->mesh_config->meshconf_pmetric) &&
	     (ifmsh->mesh_cc_id == ie->mesh_config->meshconf_congest) &&
	     (ifmsh->mesh_sp_id == ie->mesh_config->meshconf_synch) &&
	     (ifmsh->mesh_auth_id == ie->mesh_config->meshconf_auth)))
		return false;

	ieee80211_sta_get_rates(local, ie, ieee80211_get_sdata_band(sdata),
				&basic_rates);

	if (sdata->vif.bss_conf.basic_rates != basic_rates)
		return false;

	ieee80211_ht_oper_to_chandef(sdata->vif.bss_conf.chandef.chan,
				     ie->ht_operation, &sta_chan_def);

	if (!cfg80211_chandef_compatible(&sdata->vif.bss_conf.chandef,
					 &sta_chan_def))
		return false;

	return true;
}

/**
 * mesh_peer_accepts_plinks - check if an mp is willing to establish peer links
 *
 * @ie: information elements of a management frame from the mesh peer
 */
bool mesh_peer_accepts_plinks(struct ieee802_11_elems *ie)
{
	return (ie->mesh_config->meshconf_cap &
			IEEE80211_MESHCONF_CAPAB_ACCEPT_PLINKS) != 0;
}

/**
 * mesh_accept_plinks_update - update accepting_plink in local mesh beacons
 *
 * @sdata: mesh interface in which mesh beacons are going to be updated
 *
 * Returns: beacon changed flag if the beacon content changed.
 */
u32 mesh_accept_plinks_update(struct ieee80211_sub_if_data *sdata)
{
	bool free_plinks;
	u32 changed = 0;

	/* In case mesh_plink_free_count > 0 and mesh_plinktbl_capacity == 0,
	 * the mesh interface might be able to establish plinks with peers that
	 * are already on the table but are not on PLINK_ESTAB state. However,
	 * in general the mesh interface is not accepting peer link requests
	 * from new peers, and that must be reflected in the beacon
	 */
	free_plinks = mesh_plink_availables(sdata);

	if (free_plinks != sdata->u.mesh.accepting_plinks) {
		sdata->u.mesh.accepting_plinks = free_plinks;
		changed = BSS_CHANGED_BEACON;
	}

	return changed;
}

/*
 * mesh_sta_cleanup - clean up any mesh sta state
 *
 * @sta: mesh sta to clean up.
 */
void mesh_sta_cleanup(struct sta_info *sta)
{
	struct ieee80211_sub_if_data *sdata = sta->sdata;
	u32 changed;

	/*
	 * maybe userspace handles peer allocation and peering, but in either
	 * case the beacon is still generated by the kernel and we might need
	 * an update.
	 */
	changed = mesh_accept_plinks_update(sdata);
	if (sdata->u.mesh.security == IEEE80211_MESH_SEC_NONE) {
		changed |= mesh_plink_deactivate(sta);
		del_timer_sync(&sta->plink_timer);
	}

	if (changed)
		ieee80211_mbss_info_change_notify(sdata, changed);
}

int mesh_rmc_init(struct ieee80211_sub_if_data *sdata)
{
	int i;

	sdata->u.mesh.rmc = kmalloc(sizeof(struct mesh_rmc), GFP_KERNEL);
	if (!sdata->u.mesh.rmc)
		return -ENOMEM;
	sdata->u.mesh.rmc->idx_mask = RMC_BUCKETS - 1;
	for (i = 0; i < RMC_BUCKETS; i++)
		INIT_LIST_HEAD(&sdata->u.mesh.rmc->bucket[i]);
	return 0;
}

void mesh_rmc_free(struct ieee80211_sub_if_data *sdata)
{
	struct mesh_rmc *rmc = sdata->u.mesh.rmc;
	struct rmc_entry *p, *n;
	int i;

	if (!sdata->u.mesh.rmc)
		return;

	for (i = 0; i < RMC_BUCKETS; i++) {
		list_for_each_entry_safe(p, n, &rmc->bucket[i], list) {
			list_del(&p->list);
			kmem_cache_free(rm_cache, p);
		}
	}

	kfree(rmc);
	sdata->u.mesh.rmc = NULL;
}

/**
 * mesh_rmc_check - Check frame in recent multicast cache and add if absent.
 *
 * @sdata:	interface
 * @sa:		source address
 * @mesh_hdr:	mesh_header
 *
 * Returns: 0 if the frame is not in the cache, nonzero otherwise.
 *
 * Checks using the source address and the mesh sequence number if we have
 * received this frame lately. If the frame is not in the cache, it is added to
 * it.
 */
int mesh_rmc_check(struct ieee80211_sub_if_data *sdata,
		   const u8 *sa, struct ieee80211s_hdr *mesh_hdr)
{
	struct mesh_rmc *rmc = sdata->u.mesh.rmc;
	u32 seqnum = 0;
	int entries = 0;
	u8 idx;
	struct rmc_entry *p, *n;

	/* Don't care about endianness since only match matters */
	memcpy(&seqnum, &mesh_hdr->seqnum, sizeof(mesh_hdr->seqnum));
	idx = le32_to_cpu(mesh_hdr->seqnum) & rmc->idx_mask;
	list_for_each_entry_safe(p, n, &rmc->bucket[idx], list) {
		++entries;
		if (time_after(jiffies, p->exp_time) ||
		    entries == RMC_QUEUE_MAX_LEN) {
			list_del(&p->list);
			kmem_cache_free(rm_cache, p);
			--entries;
		} else if ((seqnum == p->seqnum) && ether_addr_equal(sa, p->sa))
			return -1;
	}

	p = kmem_cache_alloc(rm_cache, GFP_ATOMIC);
	if (!p)
		return 0;

	p->seqnum = seqnum;
	p->exp_time = jiffies + RMC_TIMEOUT;
	memcpy(p->sa, sa, ETH_ALEN);
	list_add(&p->list, &rmc->bucket[idx]);
	return 0;
}

int mesh_add_meshconf_ie(struct ieee80211_sub_if_data *sdata,
			 struct sk_buff *skb)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	u8 *pos, neighbors;
	u8 meshconf_len = sizeof(struct ieee80211_meshconf_ie);

	if (skb_tailroom(skb) < 2 + meshconf_len)
		return -ENOMEM;

	pos = skb_put(skb, 2 + meshconf_len);
	*pos++ = WLAN_EID_MESH_CONFIG;
	*pos++ = meshconf_len;

	/* Active path selection protocol ID */
	*pos++ = ifmsh->mesh_pp_id;
	/* Active path selection metric ID   */
	*pos++ = ifmsh->mesh_pm_id;
	/* Congestion control mode identifier */
	*pos++ = ifmsh->mesh_cc_id;
	/* Synchronization protocol identifier */
	*pos++ = ifmsh->mesh_sp_id;
	/* Authentication Protocol identifier */
	*pos++ = ifmsh->mesh_auth_id;
	/* Mesh Formation Info - number of neighbors */
	neighbors = atomic_read(&ifmsh->estab_plinks);
	/* Number of neighbor mesh STAs or 15 whichever is smaller */
	neighbors = (neighbors > 15) ? 15 : neighbors;
	*pos++ = neighbors << 1;
	/* Mesh capability */
	*pos = IEEE80211_MESHCONF_CAPAB_FORWARDING;
	*pos |= ifmsh->accepting_plinks ?
			IEEE80211_MESHCONF_CAPAB_ACCEPT_PLINKS : 0x00;
	/* Mesh PS mode. See IEEE802.11-2012 8.4.2.100.8 */
	*pos |= ifmsh->ps_peers_deep_sleep ?
			IEEE80211_MESHCONF_CAPAB_POWER_SAVE_LEVEL : 0x00;
	*pos++ |= ifmsh->adjusting_tbtt ?
			IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING : 0x00;
	*pos++ = 0x00;

	return 0;
}

int mesh_add_meshid_ie(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	u8 *pos;

	if (skb_tailroom(skb) < 2 + ifmsh->mesh_id_len)
		return -ENOMEM;

	pos = skb_put(skb, 2 + ifmsh->mesh_id_len);
	*pos++ = WLAN_EID_MESH_ID;
	*pos++ = ifmsh->mesh_id_len;
	if (ifmsh->mesh_id_len)
		memcpy(pos, ifmsh->mesh_id, ifmsh->mesh_id_len);

	return 0;
}

static int mesh_add_awake_window_ie(struct ieee80211_sub_if_data *sdata,
				    struct sk_buff *skb)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	u8 *pos;

	/* see IEEE802.11-2012 13.14.6 */
	if (ifmsh->ps_peers_light_sleep == 0 &&
	    ifmsh->ps_peers_deep_sleep == 0 &&
	    ifmsh->nonpeer_pm == NL80211_MESH_POWER_ACTIVE)
		return 0;

	if (skb_tailroom(skb) < 4)
		return -ENOMEM;

	pos = skb_put(skb, 2 + 2);
	*pos++ = WLAN_EID_MESH_AWAKE_WINDOW;
	*pos++ = 2;
	put_unaligned_le16(ifmsh->mshcfg.dot11MeshAwakeWindowDuration, pos);

	return 0;
}

int mesh_add_vendor_ies(struct ieee80211_sub_if_data *sdata,
			struct sk_buff *skb)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	u8 offset, len;
	const u8 *data;

	if (!ifmsh->ie || !ifmsh->ie_len)
		return 0;

	/* fast-forward to vendor IEs */
	offset = ieee80211_ie_split_vendor(ifmsh->ie, ifmsh->ie_len, 0);

	if (offset) {
		len = ifmsh->ie_len - offset;
		data = ifmsh->ie + offset;
		if (skb_tailroom(skb) < len)
			return -ENOMEM;
		memcpy(skb_put(skb, len), data, len);
	}

	return 0;
}

int mesh_add_rsn_ie(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	u8 len = 0;
	const u8 *data;

	if (!ifmsh->ie || !ifmsh->ie_len)
		return 0;

	/* find RSN IE */
	data = ifmsh->ie;
	while (data < ifmsh->ie + ifmsh->ie_len) {
		if (*data == WLAN_EID_RSN) {
			len = data[1] + 2;
			break;
		}
		data++;
	}

	if (len) {
		if (skb_tailroom(skb) < len)
			return -ENOMEM;
		memcpy(skb_put(skb, len), data, len);
	}

	return 0;
}

static int mesh_add_ds_params_ie(struct ieee80211_sub_if_data *sdata,
				 struct sk_buff *skb)
{
	struct ieee80211_chanctx_conf *chanctx_conf;
	struct ieee80211_channel *chan;
	u8 *pos;

	if (skb_tailroom(skb) < 3)
		return -ENOMEM;

	rcu_read_lock();
	chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
	if (WARN_ON(!chanctx_conf)) {
		rcu_read_unlock();
		return -EINVAL;
	}
	chan = chanctx_conf->def.chan;
	rcu_read_unlock();

	pos = skb_put(skb, 2 + 1);
	*pos++ = WLAN_EID_DS_PARAMS;
	*pos++ = 1;
	*pos++ = ieee80211_frequency_to_channel(chan->center_freq);

	return 0;
}

int mesh_add_ht_cap_ie(struct ieee80211_sub_if_data *sdata,
		       struct sk_buff *skb)
{
	struct ieee80211_local *local = sdata->local;
	enum ieee80211_band band = ieee80211_get_sdata_band(sdata);
	struct ieee80211_supported_band *sband;
	u8 *pos;

	sband = local->hw.wiphy->bands[band];
	if (!sband->ht_cap.ht_supported ||
	    sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_20_NOHT)
		return 0;

	if (skb_tailroom(skb) < 2 + sizeof(struct ieee80211_ht_cap))
		return -ENOMEM;

	pos = skb_put(skb, 2 + sizeof(struct ieee80211_ht_cap));
	ieee80211_ie_build_ht_cap(pos, &sband->ht_cap, sband->ht_cap.cap);

	return 0;
}

int mesh_add_ht_oper_ie(struct ieee80211_sub_if_data *sdata,
			struct sk_buff *skb)
{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_chanctx_conf *chanctx_conf;
	struct ieee80211_channel *channel;
	enum nl80211_channel_type channel_type =
		cfg80211_get_chandef_type(&sdata->vif.bss_conf.chandef);
	struct ieee80211_supported_band *sband;
	struct ieee80211_sta_ht_cap *ht_cap;
	u8 *pos;

	rcu_read_lock();
	chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
	if (WARN_ON(!chanctx_conf)) {
		rcu_read_unlock();
		return -EINVAL;
	}
	channel = chanctx_conf->def.chan;
	rcu_read_unlock();

	sband = local->hw.wiphy->bands[channel->band];
	ht_cap = &sband->ht_cap;

	if (!ht_cap->ht_supported || channel_type == NL80211_CHAN_NO_HT)
		return 0;

	if (skb_tailroom(skb) < 2 + sizeof(struct ieee80211_ht_operation))
		return -ENOMEM;

	pos = skb_put(skb, 2 + sizeof(struct ieee80211_ht_operation));
	ieee80211_ie_build_ht_oper(pos, ht_cap, &sdata->vif.bss_conf.chandef,
				   sdata->vif.bss_conf.ht_operation_mode);

	return 0;
}

static void ieee80211_mesh_path_timer(unsigned long data)
{
	struct ieee80211_sub_if_data *sdata =
		(struct ieee80211_sub_if_data *) data;
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct ieee80211_local *local = sdata->local;

	if (local->quiescing) {
		set_bit(TMR_RUNNING_MP, &ifmsh->timers_running);
		return;
	}

	ieee80211_queue_work(&local->hw, &sdata->work);
}

static void ieee80211_mesh_path_root_timer(unsigned long data)
{
	struct ieee80211_sub_if_data *sdata =
		(struct ieee80211_sub_if_data *) data;
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct ieee80211_local *local = sdata->local;

	set_bit(MESH_WORK_ROOT, &ifmsh->wrkq_flags);

	if (local->quiescing) {
		set_bit(TMR_RUNNING_MPR, &ifmsh->timers_running);
		return;
	}

	ieee80211_queue_work(&local->hw, &sdata->work);
}

void ieee80211_mesh_root_setup(struct ieee80211_if_mesh *ifmsh)
{
	if (ifmsh->mshcfg.dot11MeshHWMPRootMode > IEEE80211_ROOTMODE_ROOT)
		set_bit(MESH_WORK_ROOT, &ifmsh->wrkq_flags);
	else {
		clear_bit(MESH_WORK_ROOT, &ifmsh->wrkq_flags);
		/* stop running timer */
		del_timer_sync(&ifmsh->mesh_path_root_timer);
	}
}

/**
 * ieee80211_fill_mesh_addresses - fill addresses of a locally originated mesh frame
 * @hdr:	802.11 frame header
 * @fc:		frame control field
 * @meshda:	destination address in the mesh
 * @meshsa:	source address address in the mesh.  Same as TA, as frame is
 *              locally originated.
 *
 * Return the length of the 802.11 (does not include a mesh control header)
 */
int ieee80211_fill_mesh_addresses(struct ieee80211_hdr *hdr, __le16 *fc,
				  const u8 *meshda, const u8 *meshsa)
{
	if (is_multicast_ether_addr(meshda)) {
		*fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
		/* DA TA SA */
		memcpy(hdr->addr1, meshda, ETH_ALEN);
		memcpy(hdr->addr2, meshsa, ETH_ALEN);
		memcpy(hdr->addr3, meshsa, ETH_ALEN);
		return 24;
	} else {
		*fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS);
		/* RA TA DA SA */
		memset(hdr->addr1, 0, ETH_ALEN);   /* RA is resolved later */
		memcpy(hdr->addr2, meshsa, ETH_ALEN);
		memcpy(hdr->addr3, meshda, ETH_ALEN);
		memcpy(hdr->addr4, meshsa, ETH_ALEN);
		return 30;
	}
}

/**
 * ieee80211_new_mesh_header - create a new mesh header
 * @sdata:	mesh interface to be used
 * @meshhdr:    uninitialized mesh header
 * @addr4or5:   1st address in the ae header, which may correspond to address 4
 *              (if addr6 is NULL) or address 5 (if addr6 is present). It may
 *              be NULL.
 * @addr6:	2nd address in the ae header, which corresponds to addr6 of the
 *              mesh frame
 *
 * Return the header length.
 */
int ieee80211_new_mesh_header(struct ieee80211_sub_if_data *sdata,
			      struct ieee80211s_hdr *meshhdr,
			      const char *addr4or5, const char *addr6)
{
	if (WARN_ON(!addr4or5 && addr6))
		return 0;

	memset(meshhdr, 0, sizeof(*meshhdr));

	meshhdr->ttl = sdata->u.mesh.mshcfg.dot11MeshTTL;

	/* FIXME: racy -- TX on multiple queues can be concurrent */
	put_unaligned(cpu_to_le32(sdata->u.mesh.mesh_seqnum), &meshhdr->seqnum);
	sdata->u.mesh.mesh_seqnum++;

	if (addr4or5 && !addr6) {
		meshhdr->flags |= MESH_FLAGS_AE_A4;
		memcpy(meshhdr->eaddr1, addr4or5, ETH_ALEN);
		return 2 * ETH_ALEN;
	} else if (addr4or5 && addr6) {
		meshhdr->flags |= MESH_FLAGS_AE_A5_A6;
		memcpy(meshhdr->eaddr1, addr4or5, ETH_ALEN);
		memcpy(meshhdr->eaddr2, addr6, ETH_ALEN);
		return 3 * ETH_ALEN;
	}

	return ETH_ALEN;
}

static void ieee80211_mesh_housekeeping(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	u32 changed;

	ieee80211_sta_expire(sdata, IEEE80211_MESH_PEER_INACTIVITY_LIMIT);
	mesh_path_expire(sdata);

	changed = mesh_accept_plinks_update(sdata);
	ieee80211_mbss_info_change_notify(sdata, changed);

	mod_timer(&ifmsh->housekeeping_timer,
		  round_jiffies(jiffies +
				IEEE80211_MESH_HOUSEKEEPING_INTERVAL));
}

static void ieee80211_mesh_rootpath(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	u32 interval;

	mesh_path_tx_root_frame(sdata);

	if (ifmsh->mshcfg.dot11MeshHWMPRootMode == IEEE80211_PROACTIVE_RANN)
		interval = ifmsh->mshcfg.dot11MeshHWMPRannInterval;
	else
		interval = ifmsh->mshcfg.dot11MeshHWMProotInterval;

	mod_timer(&ifmsh->mesh_path_root_timer,
		  round_jiffies(TU_TO_EXP_TIME(interval)));
}

#ifdef CONFIG_PM
void ieee80211_mesh_quiesce(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;

	/* use atomic bitops in case all timers fire at the same time */

	if (del_timer_sync(&ifmsh->housekeeping_timer))
		set_bit(TMR_RUNNING_HK, &ifmsh->timers_running);
	if (del_timer_sync(&ifmsh->mesh_path_timer))
		set_bit(TMR_RUNNING_MP, &ifmsh->timers_running);
	if (del_timer_sync(&ifmsh->mesh_path_root_timer))
		set_bit(TMR_RUNNING_MPR, &ifmsh->timers_running);
}

void ieee80211_mesh_restart(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;

	if (test_and_clear_bit(TMR_RUNNING_HK, &ifmsh->timers_running))
		add_timer(&ifmsh->housekeeping_timer);
	if (test_and_clear_bit(TMR_RUNNING_MP, &ifmsh->timers_running))
		add_timer(&ifmsh->mesh_path_timer);
	if (test_and_clear_bit(TMR_RUNNING_MPR, &ifmsh->timers_running))
		add_timer(&ifmsh->mesh_path_root_timer);
	ieee80211_mesh_root_setup(ifmsh);
}
#endif

static int
ieee80211_mesh_build_beacon(struct ieee80211_if_mesh *ifmsh)
{
	struct beacon_data *bcn;
	int head_len, tail_len;
	struct sk_buff *skb;
	struct ieee80211_mgmt *mgmt;
	struct ieee80211_chanctx_conf *chanctx_conf;
	enum ieee80211_band band;
	u8 *pos;
	struct ieee80211_sub_if_data *sdata;
	int hdr_len = offsetof(struct ieee80211_mgmt, u.beacon) +
		      sizeof(mgmt->u.beacon);

	sdata = container_of(ifmsh, struct ieee80211_sub_if_data, u.mesh);
	rcu_read_lock();
	chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
	band = chanctx_conf->def.chan->band;
	rcu_read_unlock();

	head_len = hdr_len +
		   2 + /* NULL SSID */
		   2 + 8 + /* supported rates */
		   2 + 3; /* DS params */
	tail_len = 2 + (IEEE80211_MAX_SUPP_RATES - 8) +
		   2 + sizeof(struct ieee80211_ht_cap) +
		   2 + sizeof(struct ieee80211_ht_operation) +
		   2 + ifmsh->mesh_id_len +
		   2 + sizeof(struct ieee80211_meshconf_ie) +
		   2 + sizeof(__le16) + /* awake window */
		   ifmsh->ie_len;

	bcn = kzalloc(sizeof(*bcn) + head_len + tail_len, GFP_KERNEL);
	/* need an skb for IE builders to operate on */
	skb = dev_alloc_skb(max(head_len, tail_len));

	if (!bcn || !skb)
		goto out_free;

	/*
	 * pointers go into the block we allocated,
	 * memory is | beacon_data | head | tail |
	 */
	bcn->head = ((u8 *) bcn) + sizeof(*bcn);

	/* fill in the head */
	mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
	memset(mgmt, 0, hdr_len);
	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
					  IEEE80211_STYPE_BEACON);
	eth_broadcast_addr(mgmt->da);
	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
	memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
	ieee80211_mps_set_frame_flags(sdata, NULL, (void *) mgmt);
	mgmt->u.beacon.beacon_int =
		cpu_to_le16(sdata->vif.bss_conf.beacon_int);
	mgmt->u.beacon.capab_info |= cpu_to_le16(
		sdata->u.mesh.security ? WLAN_CAPABILITY_PRIVACY : 0);

	pos = skb_put(skb, 2);
	*pos++ = WLAN_EID_SSID;
	*pos++ = 0x0;

	if (ieee80211_add_srates_ie(sdata, skb, true, band) ||
	    mesh_add_ds_params_ie(sdata, skb))
		goto out_free;

	bcn->head_len = skb->len;
	memcpy(bcn->head, skb->data, bcn->head_len);

	/* now the tail */
	skb_trim(skb, 0);
	bcn->tail = bcn->head + bcn->head_len;

	if (ieee80211_add_ext_srates_ie(sdata, skb, true, band) ||
	    mesh_add_rsn_ie(sdata, skb) ||
	    mesh_add_ht_cap_ie(sdata, skb) ||
	    mesh_add_ht_oper_ie(sdata, skb) ||
	    mesh_add_meshid_ie(sdata, skb) ||
	    mesh_add_meshconf_ie(sdata, skb) ||
	    mesh_add_awake_window_ie(sdata, skb) ||
	    mesh_add_vendor_ies(sdata, skb))
		goto out_free;

	bcn->tail_len = skb->len;
	memcpy(bcn->tail, skb->data, bcn->tail_len);

	dev_kfree_skb(skb);
	rcu_assign_pointer(ifmsh->beacon, bcn);
	return 0;
out_free:
	kfree(bcn);
	dev_kfree_skb(skb);
	return -ENOMEM;
}

static int
ieee80211_mesh_rebuild_beacon(struct ieee80211_if_mesh *ifmsh)
{
	struct ieee80211_sub_if_data *sdata;
	struct beacon_data *old_bcn;
	int ret;
	sdata = container_of(ifmsh, struct ieee80211_sub_if_data, u.mesh);

	mutex_lock(&ifmsh->mtx);

	old_bcn = rcu_dereference_protected(ifmsh->beacon,
					    lockdep_is_held(&ifmsh->mtx));
	ret = ieee80211_mesh_build_beacon(ifmsh);
	if (ret)
		/* just reuse old beacon */
		goto out;

	if (old_bcn)
		kfree_rcu(old_bcn, rcu_head);
out:
	mutex_unlock(&ifmsh->mtx);
	return ret;
}

void ieee80211_mbss_info_change_notify(struct ieee80211_sub_if_data *sdata,
				       u32 changed)
{
	if (sdata->vif.bss_conf.enable_beacon &&
	    (changed & (BSS_CHANGED_BEACON |
			BSS_CHANGED_HT |
			BSS_CHANGED_BASIC_RATES |
			BSS_CHANGED_BEACON_INT)))
		if (ieee80211_mesh_rebuild_beacon(&sdata->u.mesh))
			return;
	ieee80211_bss_info_change_notify(sdata, changed);
}

int ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct ieee80211_local *local = sdata->local;
	u32 changed = BSS_CHANGED_BEACON |
		      BSS_CHANGED_BEACON_ENABLED |
		      BSS_CHANGED_HT |
		      BSS_CHANGED_BASIC_RATES |
		      BSS_CHANGED_BEACON_INT;
	enum ieee80211_band band = ieee80211_get_sdata_band(sdata);

	local->fif_other_bss++;
	/* mesh ifaces must set allmulti to forward mcast traffic */
	atomic_inc(&local->iff_allmultis);
	ieee80211_configure_filter(local);

	ifmsh->mesh_cc_id = 0;	/* Disabled */
	ifmsh->mesh_auth_id = 0;	/* Disabled */
	/* register sync ops from extensible synchronization framework */
	ifmsh->sync_ops = ieee80211_mesh_sync_ops_get(ifmsh->mesh_sp_id);
	ifmsh->adjusting_tbtt = false;
	ifmsh->sync_offset_clockdrift_max = 0;
	set_bit(MESH_WORK_HOUSEKEEPING, &ifmsh->wrkq_flags);
	ieee80211_mesh_root_setup(ifmsh);
	ieee80211_queue_work(&local->hw, &sdata->work);
	sdata->vif.bss_conf.ht_operation_mode =
				ifmsh->mshcfg.ht_opmode;
	sdata->vif.bss_conf.enable_beacon = true;
	sdata->vif.bss_conf.basic_rates =
		ieee80211_mandatory_rates(local, band);

	changed |= ieee80211_mps_local_status_update(sdata);

	if (ieee80211_mesh_build_beacon(ifmsh)) {
		ieee80211_stop_mesh(sdata);
		return -ENOMEM;
	}

	ieee80211_bss_info_change_notify(sdata, changed);

	netif_carrier_on(sdata->dev);
	return 0;
}

void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct beacon_data *bcn;

	netif_carrier_off(sdata->dev);

	/* stop the beacon */
	ifmsh->mesh_id_len = 0;
	sdata->vif.bss_conf.enable_beacon = false;
	clear_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED, &sdata->state);
	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED);
	mutex_lock(&ifmsh->mtx);
	bcn = rcu_dereference_protected(ifmsh->beacon,
					lockdep_is_held(&ifmsh->mtx));
	rcu_assign_pointer(ifmsh->beacon, NULL);
	kfree_rcu(bcn, rcu_head);
	mutex_unlock(&ifmsh->mtx);

	/* flush STAs and mpaths on this iface */
	sta_info_flush(sdata);
	mesh_path_flush_by_iface(sdata);

	/* free all potentially still buffered group-addressed frames */
	local->total_ps_buffered -= skb_queue_len(&ifmsh->ps.bc_buf);
	skb_queue_purge(&ifmsh->ps.bc_buf);

	del_timer_sync(&sdata->u.mesh.housekeeping_timer);
	del_timer_sync(&sdata->u.mesh.mesh_path_root_timer);
	del_timer_sync(&sdata->u.mesh.mesh_path_timer);
	/*
	 * If the timer fired while we waited for it, it will have
	 * requeued the work. Now the work will be running again
	 * but will not rearm the timer again because it checks
	 * whether the interface is running, which, at this point,
	 * it no longer is.
	 */
	cancel_work_sync(&sdata->work);

	local->fif_other_bss--;
	atomic_dec(&local->iff_allmultis);
	ieee80211_configure_filter(local);

	sdata->u.mesh.timers_running = 0;
}

static void
ieee80211_mesh_rx_probe_req(struct ieee80211_sub_if_data *sdata,
			    struct ieee80211_mgmt *mgmt, size_t len)
{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct sk_buff *presp;
	struct beacon_data *bcn;
	struct ieee80211_mgmt *hdr;
	struct ieee802_11_elems elems;
	size_t baselen;
	u8 *pos, *end;

	end = ((u8 *) mgmt) + len;
	pos = mgmt->u.probe_req.variable;
	baselen = (u8 *) pos - (u8 *) mgmt;
	if (baselen > len)
		return;

	ieee802_11_parse_elems(pos, len - baselen, &elems);

	/* 802.11-2012 10.1.4.3.2 */
	if ((!ether_addr_equal(mgmt->da, sdata->vif.addr) &&
	     !is_broadcast_ether_addr(mgmt->da)) ||
	    elems.ssid_len != 0)
		return;

	if (elems.mesh_id_len != 0 &&
	    (elems.mesh_id_len != ifmsh->mesh_id_len ||
	     memcmp(elems.mesh_id, ifmsh->mesh_id, ifmsh->mesh_id_len)))
		return;

	rcu_read_lock();
	bcn = rcu_dereference(ifmsh->beacon);

	if (!bcn)
		goto out;

	presp = dev_alloc_skb(local->tx_headroom +
			      bcn->head_len + bcn->tail_len);
	if (!presp)
		goto out;

	skb_reserve(presp, local->tx_headroom);
	memcpy(skb_put(presp, bcn->head_len), bcn->head, bcn->head_len);
	memcpy(skb_put(presp, bcn->tail_len), bcn->tail, bcn->tail_len);
	hdr = (struct ieee80211_mgmt *) presp->data;
	hdr->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
					 IEEE80211_STYPE_PROBE_RESP);
	memcpy(hdr->da, mgmt->sa, ETH_ALEN);
	IEEE80211_SKB_CB(presp)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;
	ieee80211_tx_skb(sdata, presp);
out:
	rcu_read_unlock();
}

static void ieee80211_mesh_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
					u16 stype,
					struct ieee80211_mgmt *mgmt,
					size_t len,
					struct ieee80211_rx_status *rx_status)
{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct ieee802_11_elems elems;
	struct ieee80211_channel *channel;
	size_t baselen;
	int freq;
	enum ieee80211_band band = rx_status->band;

	/* ignore ProbeResp to foreign address */
	if (stype == IEEE80211_STYPE_PROBE_RESP &&
	    !ether_addr_equal(mgmt->da, sdata->vif.addr))
		return;

	baselen = (u8 *) mgmt->u.probe_resp.variable - (u8 *) mgmt;
	if (baselen > len)
		return;

	ieee802_11_parse_elems(mgmt->u.probe_resp.variable, len - baselen,
			       &elems);

	/* ignore non-mesh or secure / unsecure mismatch */
	if ((!elems.mesh_id || !elems.mesh_config) ||
	    (elems.rsn && sdata->u.mesh.security == IEEE80211_MESH_SEC_NONE) ||
	    (!elems.rsn && sdata->u.mesh.security != IEEE80211_MESH_SEC_NONE))
		return;

	if (elems.ds_params && elems.ds_params_len == 1)
		freq = ieee80211_channel_to_frequency(elems.ds_params[0], band);
	else
		freq = rx_status->freq;

	channel = ieee80211_get_channel(local->hw.wiphy, freq);

	if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
		return;

	if (mesh_matches_local(sdata, &elems))
		mesh_neighbour_update(sdata, mgmt->sa, &elems);

	if (ifmsh->sync_ops)
		ifmsh->sync_ops->rx_bcn_presp(sdata,
			stype, mgmt, &elems, rx_status);
}

static void ieee80211_mesh_rx_mgmt_action(struct ieee80211_sub_if_data *sdata,
					  struct ieee80211_mgmt *mgmt,
					  size_t len,
					  struct ieee80211_rx_status *rx_status)
{
	switch (mgmt->u.action.category) {
	case WLAN_CATEGORY_SELF_PROTECTED:
		switch (mgmt->u.action.u.self_prot.action_code) {
		case WLAN_SP_MESH_PEERING_OPEN:
		case WLAN_SP_MESH_PEERING_CLOSE:
		case WLAN_SP_MESH_PEERING_CONFIRM:
			mesh_rx_plink_frame(sdata, mgmt, len, rx_status);
			break;
		}
		break;
	case WLAN_CATEGORY_MESH_ACTION:
		if (mesh_action_is_path_sel(mgmt))
			mesh_rx_path_sel_frame(sdata, mgmt, len);
		break;
	}
}

void ieee80211_mesh_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata,
				   struct sk_buff *skb)
{
	struct ieee80211_rx_status *rx_status;
	struct ieee80211_mgmt *mgmt;
	u16 stype;

	rx_status = IEEE80211_SKB_RXCB(skb);
	mgmt = (struct ieee80211_mgmt *) skb->data;
	stype = le16_to_cpu(mgmt->frame_control) & IEEE80211_FCTL_STYPE;

	switch (stype) {
	case IEEE80211_STYPE_PROBE_RESP:
	case IEEE80211_STYPE_BEACON:
		ieee80211_mesh_rx_bcn_presp(sdata, stype, mgmt, skb->len,
					    rx_status);
		break;
	case IEEE80211_STYPE_PROBE_REQ:
		ieee80211_mesh_rx_probe_req(sdata, mgmt, skb->len);
		break;
	case IEEE80211_STYPE_ACTION:
		ieee80211_mesh_rx_mgmt_action(sdata, mgmt, skb->len, rx_status);
		break;
	}
}

void ieee80211_mesh_work(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;

	if (ifmsh->preq_queue_len &&
	    time_after(jiffies,
		       ifmsh->last_preq + msecs_to_jiffies(ifmsh->mshcfg.dot11MeshHWMPpreqMinInterval)))
		mesh_path_start_discovery(sdata);

	if (test_and_clear_bit(MESH_WORK_GROW_MPATH_TABLE, &ifmsh->wrkq_flags))
		mesh_mpath_table_grow();

	if (test_and_clear_bit(MESH_WORK_GROW_MPP_TABLE, &ifmsh->wrkq_flags))
		mesh_mpp_table_grow();

	if (test_and_clear_bit(MESH_WORK_HOUSEKEEPING, &ifmsh->wrkq_flags))
		ieee80211_mesh_housekeeping(sdata);

	if (test_and_clear_bit(MESH_WORK_ROOT, &ifmsh->wrkq_flags))
		ieee80211_mesh_rootpath(sdata);

	if (test_and_clear_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags))
		mesh_sync_adjust_tbtt(sdata);
}

void ieee80211_mesh_notify_scan_completed(struct ieee80211_local *local)
{
	struct ieee80211_sub_if_data *sdata;

	rcu_read_lock();
	list_for_each_entry_rcu(sdata, &local->interfaces, list)
		if (ieee80211_vif_is_mesh(&sdata->vif))
			ieee80211_queue_work(&local->hw, &sdata->work);
	rcu_read_unlock();
}

void ieee80211_mesh_init_sdata(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	static u8 zero_addr[ETH_ALEN] = {};

	setup_timer(&ifmsh->housekeeping_timer,
		    ieee80211_mesh_housekeeping_timer,
		    (unsigned long) sdata);

	ifmsh->accepting_plinks = true;
	ifmsh->preq_id = 0;
	ifmsh->sn = 0;
	ifmsh->num_gates = 0;
	atomic_set(&ifmsh->mpaths, 0);
	mesh_rmc_init(sdata);
	ifmsh->last_preq = jiffies;
	ifmsh->next_perr = jiffies;
	/* Allocate all mesh structures when creating the first mesh interface. */
	if (!mesh_allocated)
		ieee80211s_init();
	setup_timer(&ifmsh->mesh_path_timer,
		    ieee80211_mesh_path_timer,
		    (unsigned long) sdata);
	setup_timer(&ifmsh->mesh_path_root_timer,
		    ieee80211_mesh_path_root_timer,
		    (unsigned long) sdata);
	INIT_LIST_HEAD(&ifmsh->preq_queue.list);
	skb_queue_head_init(&ifmsh->ps.bc_buf);
	spin_lock_init(&ifmsh->mesh_preq_queue_lock);
	spin_lock_init(&ifmsh->sync_offset_lock);
	RCU_INIT_POINTER(ifmsh->beacon, NULL);
	mutex_init(&ifmsh->mtx);

	sdata->vif.bss_conf.bssid = zero_addr;
}