xref: /linux/net/mac80211/mesh_plink.c (revision 26b0d14106954ae46d2f4f7eec3481828a210f7d)
1 /*
2  * Copyright (c) 2008, 2009 open80211s Ltd.
3  * Author:     Luis Carlos Cobo <luisca@cozybit.com>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  */
9 #include <linux/gfp.h>
10 #include <linux/kernel.h>
11 #include <linux/random.h>
12 #include "ieee80211_i.h"
13 #include "rate.h"
14 #include "mesh.h"
15 
16 #ifdef CONFIG_MAC80211_VERBOSE_MPL_DEBUG
17 #define mpl_dbg(fmt, args...)	printk(KERN_DEBUG fmt, ##args)
18 #else
19 #define mpl_dbg(fmt, args...)	do { (void)(0); } while (0)
20 #endif
21 
22 #define PLINK_GET_LLID(p) (p + 2)
23 #define PLINK_GET_PLID(p) (p + 4)
24 
25 #define mod_plink_timer(s, t) (mod_timer(&s->plink_timer, \
26 				jiffies + HZ * t / 1000))
27 
28 #define dot11MeshMaxRetries(s) (s->u.mesh.mshcfg.dot11MeshMaxRetries)
29 #define dot11MeshRetryTimeout(s) (s->u.mesh.mshcfg.dot11MeshRetryTimeout)
30 #define dot11MeshConfirmTimeout(s) (s->u.mesh.mshcfg.dot11MeshConfirmTimeout)
31 #define dot11MeshHoldingTimeout(s) (s->u.mesh.mshcfg.dot11MeshHoldingTimeout)
32 #define dot11MeshMaxPeerLinks(s) (s->u.mesh.mshcfg.dot11MeshMaxPeerLinks)
33 
34 /* We only need a valid sta if user configured a minimum rssi_threshold. */
35 #define rssi_threshold_check(sta, sdata) \
36 		(sdata->u.mesh.mshcfg.rssi_threshold == 0 ||\
37 		(sta && (s8) -ewma_read(&sta->avg_signal) > \
38 		sdata->u.mesh.mshcfg.rssi_threshold))
39 
40 enum plink_event {
41 	PLINK_UNDEFINED,
42 	OPN_ACPT,
43 	OPN_RJCT,
44 	OPN_IGNR,
45 	CNF_ACPT,
46 	CNF_RJCT,
47 	CNF_IGNR,
48 	CLS_ACPT,
49 	CLS_IGNR
50 };
51 
52 static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
53 		enum ieee80211_self_protected_actioncode action,
54 		u8 *da, __le16 llid, __le16 plid, __le16 reason);
55 
56 static inline
57 void mesh_plink_inc_estab_count(struct ieee80211_sub_if_data *sdata)
58 {
59 	atomic_inc(&sdata->u.mesh.mshstats.estab_plinks);
60 	mesh_accept_plinks_update(sdata);
61 }
62 
63 static inline
64 void mesh_plink_dec_estab_count(struct ieee80211_sub_if_data *sdata)
65 {
66 	atomic_dec(&sdata->u.mesh.mshstats.estab_plinks);
67 	mesh_accept_plinks_update(sdata);
68 }
69 
70 /**
71  * mesh_plink_fsm_restart - restart a mesh peer link finite state machine
72  *
73  * @sta: mesh peer link to restart
74  *
75  * Locking: this function must be called holding sta->lock
76  */
77 static inline void mesh_plink_fsm_restart(struct sta_info *sta)
78 {
79 	sta->plink_state = NL80211_PLINK_LISTEN;
80 	sta->llid = sta->plid = sta->reason = 0;
81 	sta->plink_retries = 0;
82 }
83 
84 /*
85  * Allocate mesh sta entry and insert into station table
86  */
87 static struct sta_info *mesh_plink_alloc(struct ieee80211_sub_if_data *sdata,
88 					 u8 *hw_addr)
89 {
90 	struct sta_info *sta;
91 
92 	if (sdata->local->num_sta >= MESH_MAX_PLINKS)
93 		return NULL;
94 
95 	sta = sta_info_alloc(sdata, hw_addr, GFP_KERNEL);
96 	if (!sta)
97 		return NULL;
98 
99 	sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
100 	sta_info_pre_move_state(sta, IEEE80211_STA_ASSOC);
101 	sta_info_pre_move_state(sta, IEEE80211_STA_AUTHORIZED);
102 
103 	set_sta_flag(sta, WLAN_STA_WME);
104 
105 	return sta;
106 }
107 
108 /*
109  * mesh_set_ht_prot_mode - set correct HT protection mode
110  *
111  * Section 9.23.3.5 of IEEE 80211-2012 describes the protection rules for HT
112  * mesh STA in a MBSS. Three HT protection modes are supported for now, non-HT
113  * mixed mode, 20MHz-protection and no-protection mode. non-HT mixed mode is
114  * selected if any non-HT peers are present in our MBSS.  20MHz-protection mode
115  * is selected if all peers in our 20/40MHz MBSS support HT and atleast one
116  * HT20 peer is present. Otherwise no-protection mode is selected.
117  */
118 static u32 mesh_set_ht_prot_mode(struct ieee80211_sub_if_data *sdata)
119 {
120 	struct ieee80211_local *local = sdata->local;
121 	struct sta_info *sta;
122 	u32 changed = 0;
123 	u16 ht_opmode;
124 	bool non_ht_sta = false, ht20_sta = false;
125 
126 	if (local->_oper_channel_type == NL80211_CHAN_NO_HT)
127 		return 0;
128 
129 	rcu_read_lock();
130 	list_for_each_entry_rcu(sta, &local->sta_list, list) {
131 		if (sdata != sta->sdata ||
132 		    sta->plink_state != NL80211_PLINK_ESTAB)
133 			continue;
134 
135 		switch (sta->ch_type) {
136 		case NL80211_CHAN_NO_HT:
137 			mpl_dbg("mesh_plink %pM: nonHT sta (%pM) is present",
138 				sdata->vif.addr, sta->sta.addr);
139 			non_ht_sta = true;
140 			goto out;
141 		case NL80211_CHAN_HT20:
142 			mpl_dbg("mesh_plink %pM: HT20 sta (%pM) is present",
143 				sdata->vif.addr, sta->sta.addr);
144 			ht20_sta = true;
145 		default:
146 			break;
147 		}
148 	}
149 out:
150 	rcu_read_unlock();
151 
152 	if (non_ht_sta)
153 		ht_opmode = IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED;
154 	else if (ht20_sta && local->_oper_channel_type > NL80211_CHAN_HT20)
155 		ht_opmode = IEEE80211_HT_OP_MODE_PROTECTION_20MHZ;
156 	else
157 		ht_opmode = IEEE80211_HT_OP_MODE_PROTECTION_NONE;
158 
159 	if (sdata->vif.bss_conf.ht_operation_mode != ht_opmode) {
160 		sdata->vif.bss_conf.ht_operation_mode = ht_opmode;
161 		sdata->u.mesh.mshcfg.ht_opmode = ht_opmode;
162 		changed = BSS_CHANGED_HT;
163 		mpl_dbg("mesh_plink %pM: protection mode changed to %d",
164 			sdata->vif.addr, ht_opmode);
165 	}
166 
167 	return changed;
168 }
169 
170 /**
171  * __mesh_plink_deactivate - deactivate mesh peer link
172  *
173  * @sta: mesh peer link to deactivate
174  *
175  * All mesh paths with this peer as next hop will be flushed
176  *
177  * Locking: the caller must hold sta->lock
178  */
179 static bool __mesh_plink_deactivate(struct sta_info *sta)
180 {
181 	struct ieee80211_sub_if_data *sdata = sta->sdata;
182 	bool deactivated = false;
183 
184 	if (sta->plink_state == NL80211_PLINK_ESTAB) {
185 		mesh_plink_dec_estab_count(sdata);
186 		deactivated = true;
187 	}
188 	sta->plink_state = NL80211_PLINK_BLOCKED;
189 	mesh_path_flush_by_nexthop(sta);
190 
191 	return deactivated;
192 }
193 
194 /**
195  * mesh_plink_deactivate - deactivate mesh peer link
196  *
197  * @sta: mesh peer link to deactivate
198  *
199  * All mesh paths with this peer as next hop will be flushed
200  */
201 void mesh_plink_deactivate(struct sta_info *sta)
202 {
203 	struct ieee80211_sub_if_data *sdata = sta->sdata;
204 	bool deactivated;
205 
206 	spin_lock_bh(&sta->lock);
207 	deactivated = __mesh_plink_deactivate(sta);
208 	sta->reason = cpu_to_le16(WLAN_REASON_MESH_PEER_CANCELED);
209 	mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
210 			    sta->sta.addr, sta->llid, sta->plid,
211 			    sta->reason);
212 	spin_unlock_bh(&sta->lock);
213 
214 	if (deactivated)
215 		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
216 }
217 
218 static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
219 		enum ieee80211_self_protected_actioncode action,
220 		u8 *da, __le16 llid, __le16 plid, __le16 reason) {
221 	struct ieee80211_local *local = sdata->local;
222 	struct sk_buff *skb;
223 	struct ieee80211_mgmt *mgmt;
224 	bool include_plid = false;
225 	u16 peering_proto = 0;
226 	u8 *pos, ie_len = 4;
227 	int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.self_prot) +
228 		      sizeof(mgmt->u.action.u.self_prot);
229 
230 	skb = dev_alloc_skb(local->tx_headroom +
231 			    hdr_len +
232 			    2 + /* capability info */
233 			    2 + /* AID */
234 			    2 + 8 + /* supported rates */
235 			    2 + (IEEE80211_MAX_SUPP_RATES - 8) +
236 			    2 + sdata->u.mesh.mesh_id_len +
237 			    2 + sizeof(struct ieee80211_meshconf_ie) +
238 			    2 + sizeof(struct ieee80211_ht_cap) +
239 			    2 + sizeof(struct ieee80211_ht_operation) +
240 			    2 + 8 + /* peering IE */
241 			    sdata->u.mesh.ie_len);
242 	if (!skb)
243 		return -1;
244 	skb_reserve(skb, local->tx_headroom);
245 	mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
246 	memset(mgmt, 0, hdr_len);
247 	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
248 					  IEEE80211_STYPE_ACTION);
249 	memcpy(mgmt->da, da, ETH_ALEN);
250 	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
251 	memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
252 	mgmt->u.action.category = WLAN_CATEGORY_SELF_PROTECTED;
253 	mgmt->u.action.u.self_prot.action_code = action;
254 
255 	if (action != WLAN_SP_MESH_PEERING_CLOSE) {
256 		/* capability info */
257 		pos = skb_put(skb, 2);
258 		memset(pos, 0, 2);
259 		if (action == WLAN_SP_MESH_PEERING_CONFIRM) {
260 			/* AID */
261 			pos = skb_put(skb, 2);
262 			memcpy(pos + 2, &plid, 2);
263 		}
264 		if (ieee80211_add_srates_ie(&sdata->vif, skb, true) ||
265 		    ieee80211_add_ext_srates_ie(&sdata->vif, skb, true) ||
266 		    mesh_add_rsn_ie(skb, sdata) ||
267 		    mesh_add_meshid_ie(skb, sdata) ||
268 		    mesh_add_meshconf_ie(skb, sdata))
269 			return -1;
270 	} else {	/* WLAN_SP_MESH_PEERING_CLOSE */
271 		if (mesh_add_meshid_ie(skb, sdata))
272 			return -1;
273 	}
274 
275 	/* Add Mesh Peering Management element */
276 	switch (action) {
277 	case WLAN_SP_MESH_PEERING_OPEN:
278 		break;
279 	case WLAN_SP_MESH_PEERING_CONFIRM:
280 		ie_len += 2;
281 		include_plid = true;
282 		break;
283 	case WLAN_SP_MESH_PEERING_CLOSE:
284 		if (plid) {
285 			ie_len += 2;
286 			include_plid = true;
287 		}
288 		ie_len += 2;	/* reason code */
289 		break;
290 	default:
291 		return -EINVAL;
292 	}
293 
294 	if (WARN_ON(skb_tailroom(skb) < 2 + ie_len))
295 		return -ENOMEM;
296 
297 	pos = skb_put(skb, 2 + ie_len);
298 	*pos++ = WLAN_EID_PEER_MGMT;
299 	*pos++ = ie_len;
300 	memcpy(pos, &peering_proto, 2);
301 	pos += 2;
302 	memcpy(pos, &llid, 2);
303 	pos += 2;
304 	if (include_plid) {
305 		memcpy(pos, &plid, 2);
306 		pos += 2;
307 	}
308 	if (action == WLAN_SP_MESH_PEERING_CLOSE) {
309 		memcpy(pos, &reason, 2);
310 		pos += 2;
311 	}
312 
313 	if (action != WLAN_SP_MESH_PEERING_CLOSE) {
314 		if (mesh_add_ht_cap_ie(skb, sdata) ||
315 		    mesh_add_ht_oper_ie(skb, sdata))
316 			return -1;
317 	}
318 
319 	if (mesh_add_vendor_ies(skb, sdata))
320 		return -1;
321 
322 	ieee80211_tx_skb(sdata, skb);
323 	return 0;
324 }
325 
326 /* mesh_peer_init - initialize new mesh peer and return resulting sta_info
327  *
328  * @sdata: local meshif
329  * @addr: peer's address
330  * @elems: IEs from beacon or mesh peering frame
331  *
332  * call under RCU
333  */
334 static struct sta_info *mesh_peer_init(struct ieee80211_sub_if_data *sdata,
335 				       u8 *addr,
336 				       struct ieee802_11_elems *elems)
337 {
338 	struct ieee80211_local *local = sdata->local;
339 	enum ieee80211_band band = local->oper_channel->band;
340 	struct ieee80211_supported_band *sband;
341 	u32 rates, basic_rates = 0;
342 	struct sta_info *sta;
343 	bool insert = false;
344 
345 	sband = local->hw.wiphy->bands[band];
346 	rates = ieee80211_sta_get_rates(local, elems, band, &basic_rates);
347 
348 	sta = sta_info_get(sdata, addr);
349 	if (!sta) {
350 		/* Userspace handles peer allocation when security is enabled */
351 		if (sdata->u.mesh.security & IEEE80211_MESH_SEC_AUTHED) {
352 			cfg80211_notify_new_peer_candidate(sdata->dev, addr,
353 							   elems->ie_start,
354 							   elems->total_len,
355 							   GFP_ATOMIC);
356 			return NULL;
357 		}
358 
359 		sta = mesh_plink_alloc(sdata, addr);
360 		if (!sta)
361 			return NULL;
362 		insert = true;
363 	}
364 
365 	spin_lock_bh(&sta->lock);
366 	sta->last_rx = jiffies;
367 	sta->sta.supp_rates[band] = rates;
368 	if (elems->ht_cap_elem &&
369 	    sdata->local->_oper_channel_type != NL80211_CHAN_NO_HT)
370 		ieee80211_ht_cap_ie_to_sta_ht_cap(sdata, sband,
371 						  elems->ht_cap_elem,
372 						  &sta->sta.ht_cap);
373 	else
374 		memset(&sta->sta.ht_cap, 0, sizeof(sta->sta.ht_cap));
375 
376 	if (elems->ht_operation) {
377 		if (!(elems->ht_operation->ht_param &
378 		      IEEE80211_HT_PARAM_CHAN_WIDTH_ANY))
379 			sta->sta.ht_cap.cap &=
380 					    ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
381 		sta->ch_type =
382 			ieee80211_ht_oper_to_channel_type(elems->ht_operation);
383 	}
384 
385 	rate_control_rate_init(sta);
386 	spin_unlock_bh(&sta->lock);
387 
388 	if (insert && sta_info_insert(sta))
389 		return NULL;
390 
391 	return sta;
392 }
393 
394 void mesh_neighbour_update(struct ieee80211_sub_if_data *sdata,
395 			   u8 *hw_addr,
396 			   struct ieee802_11_elems *elems)
397 {
398 	struct sta_info *sta;
399 
400 	rcu_read_lock();
401 	sta = mesh_peer_init(sdata, hw_addr, elems);
402 	if (!sta)
403 		goto out;
404 
405 	if (mesh_peer_accepts_plinks(elems) &&
406 	    sta->plink_state == NL80211_PLINK_LISTEN &&
407 	    sdata->u.mesh.accepting_plinks &&
408 	    sdata->u.mesh.mshcfg.auto_open_plinks &&
409 	    rssi_threshold_check(sta, sdata))
410 		mesh_plink_open(sta);
411 
412 out:
413 	rcu_read_unlock();
414 }
415 
416 static void mesh_plink_timer(unsigned long data)
417 {
418 	struct sta_info *sta;
419 	__le16 llid, plid, reason;
420 	struct ieee80211_sub_if_data *sdata;
421 
422 	/*
423 	 * This STA is valid because sta_info_destroy() will
424 	 * del_timer_sync() this timer after having made sure
425 	 * it cannot be readded (by deleting the plink.)
426 	 */
427 	sta = (struct sta_info *) data;
428 
429 	if (sta->sdata->local->quiescing) {
430 		sta->plink_timer_was_running = true;
431 		return;
432 	}
433 
434 	spin_lock_bh(&sta->lock);
435 	if (sta->ignore_plink_timer) {
436 		sta->ignore_plink_timer = false;
437 		spin_unlock_bh(&sta->lock);
438 		return;
439 	}
440 	mpl_dbg("Mesh plink timer for %pM fired on state %d\n",
441 		sta->sta.addr, sta->plink_state);
442 	reason = 0;
443 	llid = sta->llid;
444 	plid = sta->plid;
445 	sdata = sta->sdata;
446 
447 	switch (sta->plink_state) {
448 	case NL80211_PLINK_OPN_RCVD:
449 	case NL80211_PLINK_OPN_SNT:
450 		/* retry timer */
451 		if (sta->plink_retries < dot11MeshMaxRetries(sdata)) {
452 			u32 rand;
453 			mpl_dbg("Mesh plink for %pM (retry, timeout): %d %d\n",
454 				sta->sta.addr, sta->plink_retries,
455 				sta->plink_timeout);
456 			get_random_bytes(&rand, sizeof(u32));
457 			sta->plink_timeout = sta->plink_timeout +
458 					     rand % sta->plink_timeout;
459 			++sta->plink_retries;
460 			mod_plink_timer(sta, sta->plink_timeout);
461 			spin_unlock_bh(&sta->lock);
462 			mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_OPEN,
463 					    sta->sta.addr, llid, 0, 0);
464 			break;
465 		}
466 		reason = cpu_to_le16(WLAN_REASON_MESH_MAX_RETRIES);
467 		/* fall through on else */
468 	case NL80211_PLINK_CNF_RCVD:
469 		/* confirm timer */
470 		if (!reason)
471 			reason = cpu_to_le16(WLAN_REASON_MESH_CONFIRM_TIMEOUT);
472 		sta->plink_state = NL80211_PLINK_HOLDING;
473 		mod_plink_timer(sta, dot11MeshHoldingTimeout(sdata));
474 		spin_unlock_bh(&sta->lock);
475 		mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
476 				    sta->sta.addr, llid, plid, reason);
477 		break;
478 	case NL80211_PLINK_HOLDING:
479 		/* holding timer */
480 		del_timer(&sta->plink_timer);
481 		mesh_plink_fsm_restart(sta);
482 		spin_unlock_bh(&sta->lock);
483 		break;
484 	default:
485 		spin_unlock_bh(&sta->lock);
486 		break;
487 	}
488 }
489 
490 #ifdef CONFIG_PM
491 void mesh_plink_quiesce(struct sta_info *sta)
492 {
493 	if (del_timer_sync(&sta->plink_timer))
494 		sta->plink_timer_was_running = true;
495 }
496 
497 void mesh_plink_restart(struct sta_info *sta)
498 {
499 	if (sta->plink_timer_was_running) {
500 		add_timer(&sta->plink_timer);
501 		sta->plink_timer_was_running = false;
502 	}
503 }
504 #endif
505 
506 static inline void mesh_plink_timer_set(struct sta_info *sta, int timeout)
507 {
508 	sta->plink_timer.expires = jiffies + (HZ * timeout / 1000);
509 	sta->plink_timer.data = (unsigned long) sta;
510 	sta->plink_timer.function = mesh_plink_timer;
511 	sta->plink_timeout = timeout;
512 	add_timer(&sta->plink_timer);
513 }
514 
515 int mesh_plink_open(struct sta_info *sta)
516 {
517 	__le16 llid;
518 	struct ieee80211_sub_if_data *sdata = sta->sdata;
519 
520 	if (!test_sta_flag(sta, WLAN_STA_AUTH))
521 		return -EPERM;
522 
523 	spin_lock_bh(&sta->lock);
524 	get_random_bytes(&llid, 2);
525 	sta->llid = llid;
526 	if (sta->plink_state != NL80211_PLINK_LISTEN) {
527 		spin_unlock_bh(&sta->lock);
528 		return -EBUSY;
529 	}
530 	sta->plink_state = NL80211_PLINK_OPN_SNT;
531 	mesh_plink_timer_set(sta, dot11MeshRetryTimeout(sdata));
532 	spin_unlock_bh(&sta->lock);
533 	mpl_dbg("Mesh plink: starting establishment with %pM\n",
534 		sta->sta.addr);
535 
536 	return mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_OPEN,
537 				   sta->sta.addr, llid, 0, 0);
538 }
539 
540 void mesh_plink_block(struct sta_info *sta)
541 {
542 	struct ieee80211_sub_if_data *sdata = sta->sdata;
543 	bool deactivated;
544 
545 	spin_lock_bh(&sta->lock);
546 	deactivated = __mesh_plink_deactivate(sta);
547 	sta->plink_state = NL80211_PLINK_BLOCKED;
548 	spin_unlock_bh(&sta->lock);
549 
550 	if (deactivated)
551 		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
552 }
553 
554 
555 void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_mgmt *mgmt,
556 			 size_t len, struct ieee80211_rx_status *rx_status)
557 {
558 	struct ieee802_11_elems elems;
559 	struct sta_info *sta;
560 	enum plink_event event;
561 	enum ieee80211_self_protected_actioncode ftype;
562 	size_t baselen;
563 	bool matches_local = true;
564 	u8 ie_len;
565 	u8 *baseaddr;
566 	u32 changed = 0;
567 	__le16 plid, llid, reason;
568 #ifdef CONFIG_MAC80211_VERBOSE_MPL_DEBUG
569 	static const char *mplstates[] = {
570 		[NL80211_PLINK_LISTEN] = "LISTEN",
571 		[NL80211_PLINK_OPN_SNT] = "OPN-SNT",
572 		[NL80211_PLINK_OPN_RCVD] = "OPN-RCVD",
573 		[NL80211_PLINK_CNF_RCVD] = "CNF_RCVD",
574 		[NL80211_PLINK_ESTAB] = "ESTAB",
575 		[NL80211_PLINK_HOLDING] = "HOLDING",
576 		[NL80211_PLINK_BLOCKED] = "BLOCKED"
577 	};
578 #endif
579 
580 	/* need action_code, aux */
581 	if (len < IEEE80211_MIN_ACTION_SIZE + 3)
582 		return;
583 
584 	if (is_multicast_ether_addr(mgmt->da)) {
585 		mpl_dbg("Mesh plink: ignore frame from multicast address");
586 		return;
587 	}
588 
589 	baseaddr = mgmt->u.action.u.self_prot.variable;
590 	baselen = (u8 *) mgmt->u.action.u.self_prot.variable - (u8 *) mgmt;
591 	if (mgmt->u.action.u.self_prot.action_code ==
592 						WLAN_SP_MESH_PEERING_CONFIRM) {
593 		baseaddr += 4;
594 		baselen += 4;
595 	}
596 	ieee802_11_parse_elems(baseaddr, len - baselen, &elems);
597 	if (!elems.peering) {
598 		mpl_dbg("Mesh plink: missing necessary peer link ie\n");
599 		return;
600 	}
601 	if (elems.rsn_len &&
602 			sdata->u.mesh.security == IEEE80211_MESH_SEC_NONE) {
603 		mpl_dbg("Mesh plink: can't establish link with secure peer\n");
604 		return;
605 	}
606 
607 	ftype = mgmt->u.action.u.self_prot.action_code;
608 	ie_len = elems.peering_len;
609 	if ((ftype == WLAN_SP_MESH_PEERING_OPEN && ie_len != 4) ||
610 	    (ftype == WLAN_SP_MESH_PEERING_CONFIRM && ie_len != 6) ||
611 	    (ftype == WLAN_SP_MESH_PEERING_CLOSE && ie_len != 6
612 							&& ie_len != 8)) {
613 		mpl_dbg("Mesh plink: incorrect plink ie length %d %d\n",
614 		    ftype, ie_len);
615 		return;
616 	}
617 
618 	if (ftype != WLAN_SP_MESH_PEERING_CLOSE &&
619 				(!elems.mesh_id || !elems.mesh_config)) {
620 		mpl_dbg("Mesh plink: missing necessary ie\n");
621 		return;
622 	}
623 	/* Note the lines below are correct, the llid in the frame is the plid
624 	 * from the point of view of this host.
625 	 */
626 	memcpy(&plid, PLINK_GET_LLID(elems.peering), 2);
627 	if (ftype == WLAN_SP_MESH_PEERING_CONFIRM ||
628 	    (ftype == WLAN_SP_MESH_PEERING_CLOSE && ie_len == 8))
629 		memcpy(&llid, PLINK_GET_PLID(elems.peering), 2);
630 
631 	rcu_read_lock();
632 
633 	sta = sta_info_get(sdata, mgmt->sa);
634 	if (!sta && ftype != WLAN_SP_MESH_PEERING_OPEN) {
635 		mpl_dbg("Mesh plink: cls or cnf from unknown peer\n");
636 		rcu_read_unlock();
637 		return;
638 	}
639 
640 	if (ftype == WLAN_SP_MESH_PEERING_OPEN &&
641 	    !rssi_threshold_check(sta, sdata)) {
642 		mpl_dbg("Mesh plink: %pM does not meet rssi threshold\n",
643 			mgmt->sa);
644 		rcu_read_unlock();
645 		return;
646 	}
647 
648 	if (sta && !test_sta_flag(sta, WLAN_STA_AUTH)) {
649 		mpl_dbg("Mesh plink: Action frame from non-authed peer\n");
650 		rcu_read_unlock();
651 		return;
652 	}
653 
654 	if (sta && sta->plink_state == NL80211_PLINK_BLOCKED) {
655 		rcu_read_unlock();
656 		return;
657 	}
658 
659 	/* Now we will figure out the appropriate event... */
660 	event = PLINK_UNDEFINED;
661 	if (ftype != WLAN_SP_MESH_PEERING_CLOSE &&
662 	    !mesh_matches_local(sdata, &elems)) {
663 		matches_local = false;
664 		switch (ftype) {
665 		case WLAN_SP_MESH_PEERING_OPEN:
666 			event = OPN_RJCT;
667 			break;
668 		case WLAN_SP_MESH_PEERING_CONFIRM:
669 			event = CNF_RJCT;
670 			break;
671 		default:
672 			break;
673 		}
674 	}
675 
676 	if (!sta && !matches_local) {
677 		rcu_read_unlock();
678 		reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
679 		llid = 0;
680 		mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
681 				    mgmt->sa, llid, plid, reason);
682 		return;
683 	} else if (!sta) {
684 		/* ftype == WLAN_SP_MESH_PEERING_OPEN */
685 		if (!mesh_plink_free_count(sdata)) {
686 			mpl_dbg("Mesh plink error: no more free plinks\n");
687 			rcu_read_unlock();
688 			return;
689 		}
690 		event = OPN_ACPT;
691 	} else if (matches_local) {
692 		switch (ftype) {
693 		case WLAN_SP_MESH_PEERING_OPEN:
694 			if (!mesh_plink_free_count(sdata) ||
695 			    (sta->plid && sta->plid != plid))
696 				event = OPN_IGNR;
697 			else
698 				event = OPN_ACPT;
699 			break;
700 		case WLAN_SP_MESH_PEERING_CONFIRM:
701 			if (!mesh_plink_free_count(sdata) ||
702 			    (sta->llid != llid || sta->plid != plid))
703 				event = CNF_IGNR;
704 			else
705 				event = CNF_ACPT;
706 			break;
707 		case WLAN_SP_MESH_PEERING_CLOSE:
708 			if (sta->plink_state == NL80211_PLINK_ESTAB)
709 				/* Do not check for llid or plid. This does not
710 				 * follow the standard but since multiple plinks
711 				 * per sta are not supported, it is necessary in
712 				 * order to avoid a livelock when MP A sees an
713 				 * establish peer link to MP B but MP B does not
714 				 * see it. This can be caused by a timeout in
715 				 * B's peer link establishment or B beign
716 				 * restarted.
717 				 */
718 				event = CLS_ACPT;
719 			else if (sta->plid != plid)
720 				event = CLS_IGNR;
721 			else if (ie_len == 7 && sta->llid != llid)
722 				event = CLS_IGNR;
723 			else
724 				event = CLS_ACPT;
725 			break;
726 		default:
727 			mpl_dbg("Mesh plink: unknown frame subtype\n");
728 			rcu_read_unlock();
729 			return;
730 		}
731 	}
732 
733 	if (event == OPN_ACPT) {
734 		/* allocate sta entry if necessary and update info */
735 		sta = mesh_peer_init(sdata, mgmt->sa, &elems);
736 		if (!sta) {
737 			mpl_dbg("Mesh plink: failed to init peer!\n");
738 			rcu_read_unlock();
739 			return;
740 		}
741 	}
742 
743 	mpl_dbg("Mesh plink (peer, state, llid, plid, event): %pM %s %d %d %d\n",
744 		mgmt->sa, mplstates[sta->plink_state],
745 		le16_to_cpu(sta->llid), le16_to_cpu(sta->plid),
746 		event);
747 	reason = 0;
748 	spin_lock_bh(&sta->lock);
749 	switch (sta->plink_state) {
750 		/* spin_unlock as soon as state is updated at each case */
751 	case NL80211_PLINK_LISTEN:
752 		switch (event) {
753 		case CLS_ACPT:
754 			mesh_plink_fsm_restart(sta);
755 			spin_unlock_bh(&sta->lock);
756 			break;
757 		case OPN_ACPT:
758 			sta->plink_state = NL80211_PLINK_OPN_RCVD;
759 			sta->plid = plid;
760 			get_random_bytes(&llid, 2);
761 			sta->llid = llid;
762 			mesh_plink_timer_set(sta, dot11MeshRetryTimeout(sdata));
763 			spin_unlock_bh(&sta->lock);
764 			mesh_plink_frame_tx(sdata,
765 					    WLAN_SP_MESH_PEERING_OPEN,
766 					    sta->sta.addr, llid, 0, 0);
767 			mesh_plink_frame_tx(sdata,
768 					    WLAN_SP_MESH_PEERING_CONFIRM,
769 					    sta->sta.addr, llid, plid, 0);
770 			break;
771 		default:
772 			spin_unlock_bh(&sta->lock);
773 			break;
774 		}
775 		break;
776 
777 	case NL80211_PLINK_OPN_SNT:
778 		switch (event) {
779 		case OPN_RJCT:
780 		case CNF_RJCT:
781 			reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
782 		case CLS_ACPT:
783 			if (!reason)
784 				reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
785 			sta->reason = reason;
786 			sta->plink_state = NL80211_PLINK_HOLDING;
787 			if (!mod_plink_timer(sta,
788 					     dot11MeshHoldingTimeout(sdata)))
789 				sta->ignore_plink_timer = true;
790 
791 			llid = sta->llid;
792 			spin_unlock_bh(&sta->lock);
793 			mesh_plink_frame_tx(sdata,
794 					    WLAN_SP_MESH_PEERING_CLOSE,
795 					    sta->sta.addr, llid, plid, reason);
796 			break;
797 		case OPN_ACPT:
798 			/* retry timer is left untouched */
799 			sta->plink_state = NL80211_PLINK_OPN_RCVD;
800 			sta->plid = plid;
801 			llid = sta->llid;
802 			spin_unlock_bh(&sta->lock);
803 			mesh_plink_frame_tx(sdata,
804 					    WLAN_SP_MESH_PEERING_CONFIRM,
805 					    sta->sta.addr, llid, plid, 0);
806 			break;
807 		case CNF_ACPT:
808 			sta->plink_state = NL80211_PLINK_CNF_RCVD;
809 			if (!mod_plink_timer(sta,
810 					     dot11MeshConfirmTimeout(sdata)))
811 				sta->ignore_plink_timer = true;
812 
813 			spin_unlock_bh(&sta->lock);
814 			break;
815 		default:
816 			spin_unlock_bh(&sta->lock);
817 			break;
818 		}
819 		break;
820 
821 	case NL80211_PLINK_OPN_RCVD:
822 		switch (event) {
823 		case OPN_RJCT:
824 		case CNF_RJCT:
825 			reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
826 		case CLS_ACPT:
827 			if (!reason)
828 				reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
829 			sta->reason = reason;
830 			sta->plink_state = NL80211_PLINK_HOLDING;
831 			if (!mod_plink_timer(sta,
832 					     dot11MeshHoldingTimeout(sdata)))
833 				sta->ignore_plink_timer = true;
834 
835 			llid = sta->llid;
836 			spin_unlock_bh(&sta->lock);
837 			mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
838 					    sta->sta.addr, llid, plid, reason);
839 			break;
840 		case OPN_ACPT:
841 			llid = sta->llid;
842 			spin_unlock_bh(&sta->lock);
843 			mesh_plink_frame_tx(sdata,
844 					    WLAN_SP_MESH_PEERING_CONFIRM,
845 					    sta->sta.addr, llid, plid, 0);
846 			break;
847 		case CNF_ACPT:
848 			del_timer(&sta->plink_timer);
849 			sta->plink_state = NL80211_PLINK_ESTAB;
850 			spin_unlock_bh(&sta->lock);
851 			mesh_plink_inc_estab_count(sdata);
852 			changed |= mesh_set_ht_prot_mode(sdata);
853 			changed |= BSS_CHANGED_BEACON;
854 			mpl_dbg("Mesh plink with %pM ESTABLISHED\n",
855 				sta->sta.addr);
856 			break;
857 		default:
858 			spin_unlock_bh(&sta->lock);
859 			break;
860 		}
861 		break;
862 
863 	case NL80211_PLINK_CNF_RCVD:
864 		switch (event) {
865 		case OPN_RJCT:
866 		case CNF_RJCT:
867 			reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
868 		case CLS_ACPT:
869 			if (!reason)
870 				reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
871 			sta->reason = reason;
872 			sta->plink_state = NL80211_PLINK_HOLDING;
873 			if (!mod_plink_timer(sta,
874 					     dot11MeshHoldingTimeout(sdata)))
875 				sta->ignore_plink_timer = true;
876 
877 			llid = sta->llid;
878 			spin_unlock_bh(&sta->lock);
879 			mesh_plink_frame_tx(sdata,
880 					    WLAN_SP_MESH_PEERING_CLOSE,
881 					    sta->sta.addr, llid, plid, reason);
882 			break;
883 		case OPN_ACPT:
884 			del_timer(&sta->plink_timer);
885 			sta->plink_state = NL80211_PLINK_ESTAB;
886 			spin_unlock_bh(&sta->lock);
887 			mesh_plink_inc_estab_count(sdata);
888 			changed |= mesh_set_ht_prot_mode(sdata);
889 			changed |= BSS_CHANGED_BEACON;
890 			mpl_dbg("Mesh plink with %pM ESTABLISHED\n",
891 				sta->sta.addr);
892 			mesh_plink_frame_tx(sdata,
893 					    WLAN_SP_MESH_PEERING_CONFIRM,
894 					    sta->sta.addr, llid, plid, 0);
895 			break;
896 		default:
897 			spin_unlock_bh(&sta->lock);
898 			break;
899 		}
900 		break;
901 
902 	case NL80211_PLINK_ESTAB:
903 		switch (event) {
904 		case CLS_ACPT:
905 			reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
906 			sta->reason = reason;
907 			__mesh_plink_deactivate(sta);
908 			sta->plink_state = NL80211_PLINK_HOLDING;
909 			llid = sta->llid;
910 			mod_plink_timer(sta, dot11MeshHoldingTimeout(sdata));
911 			spin_unlock_bh(&sta->lock);
912 			changed |= mesh_set_ht_prot_mode(sdata);
913 			changed |= BSS_CHANGED_BEACON;
914 			mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
915 					    sta->sta.addr, llid, plid, reason);
916 			break;
917 		case OPN_ACPT:
918 			llid = sta->llid;
919 			spin_unlock_bh(&sta->lock);
920 			mesh_plink_frame_tx(sdata,
921 					    WLAN_SP_MESH_PEERING_CONFIRM,
922 					    sta->sta.addr, llid, plid, 0);
923 			break;
924 		default:
925 			spin_unlock_bh(&sta->lock);
926 			break;
927 		}
928 		break;
929 	case NL80211_PLINK_HOLDING:
930 		switch (event) {
931 		case CLS_ACPT:
932 			if (del_timer(&sta->plink_timer))
933 				sta->ignore_plink_timer = 1;
934 			mesh_plink_fsm_restart(sta);
935 			spin_unlock_bh(&sta->lock);
936 			break;
937 		case OPN_ACPT:
938 		case CNF_ACPT:
939 		case OPN_RJCT:
940 		case CNF_RJCT:
941 			llid = sta->llid;
942 			reason = sta->reason;
943 			spin_unlock_bh(&sta->lock);
944 			mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
945 					    sta->sta.addr, llid, plid, reason);
946 			break;
947 		default:
948 			spin_unlock_bh(&sta->lock);
949 		}
950 		break;
951 	default:
952 		/* should not get here, PLINK_BLOCKED is dealt with at the
953 		 * beginning of the function
954 		 */
955 		spin_unlock_bh(&sta->lock);
956 		break;
957 	}
958 
959 	rcu_read_unlock();
960 
961 	if (changed)
962 		ieee80211_bss_info_change_notify(sdata, changed);
963 }
964