xref: /openbmc/linux/net/mac80211/mesh_plink.c (revision 95e9fd10)
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 #define PLINK_GET_LLID(p) (p + 2)
17 #define PLINK_GET_PLID(p) (p + 4)
18 
19 #define mod_plink_timer(s, t) (mod_timer(&s->plink_timer, \
20 				jiffies + HZ * t / 1000))
21 
22 #define dot11MeshMaxRetries(s) (s->u.mesh.mshcfg.dot11MeshMaxRetries)
23 #define dot11MeshRetryTimeout(s) (s->u.mesh.mshcfg.dot11MeshRetryTimeout)
24 #define dot11MeshConfirmTimeout(s) (s->u.mesh.mshcfg.dot11MeshConfirmTimeout)
25 #define dot11MeshHoldingTimeout(s) (s->u.mesh.mshcfg.dot11MeshHoldingTimeout)
26 #define dot11MeshMaxPeerLinks(s) (s->u.mesh.mshcfg.dot11MeshMaxPeerLinks)
27 
28 /* We only need a valid sta if user configured a minimum rssi_threshold. */
29 #define rssi_threshold_check(sta, sdata) \
30 		(sdata->u.mesh.mshcfg.rssi_threshold == 0 ||\
31 		(sta && (s8) -ewma_read(&sta->avg_signal) > \
32 		sdata->u.mesh.mshcfg.rssi_threshold))
33 
34 enum plink_event {
35 	PLINK_UNDEFINED,
36 	OPN_ACPT,
37 	OPN_RJCT,
38 	OPN_IGNR,
39 	CNF_ACPT,
40 	CNF_RJCT,
41 	CNF_IGNR,
42 	CLS_ACPT,
43 	CLS_IGNR
44 };
45 
46 static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
47 		enum ieee80211_self_protected_actioncode action,
48 		u8 *da, __le16 llid, __le16 plid, __le16 reason);
49 
50 static inline
51 void mesh_plink_inc_estab_count(struct ieee80211_sub_if_data *sdata)
52 {
53 	atomic_inc(&sdata->u.mesh.mshstats.estab_plinks);
54 	mesh_accept_plinks_update(sdata);
55 }
56 
57 static inline
58 void mesh_plink_dec_estab_count(struct ieee80211_sub_if_data *sdata)
59 {
60 	atomic_dec(&sdata->u.mesh.mshstats.estab_plinks);
61 	mesh_accept_plinks_update(sdata);
62 }
63 
64 /**
65  * mesh_plink_fsm_restart - restart a mesh peer link finite state machine
66  *
67  * @sta: mesh peer link to restart
68  *
69  * Locking: this function must be called holding sta->lock
70  */
71 static inline void mesh_plink_fsm_restart(struct sta_info *sta)
72 {
73 	sta->plink_state = NL80211_PLINK_LISTEN;
74 	sta->llid = sta->plid = sta->reason = 0;
75 	sta->plink_retries = 0;
76 }
77 
78 /*
79  * Allocate mesh sta entry and insert into station table
80  */
81 static struct sta_info *mesh_plink_alloc(struct ieee80211_sub_if_data *sdata,
82 					 u8 *hw_addr)
83 {
84 	struct sta_info *sta;
85 
86 	if (sdata->local->num_sta >= MESH_MAX_PLINKS)
87 		return NULL;
88 
89 	sta = sta_info_alloc(sdata, hw_addr, GFP_KERNEL);
90 	if (!sta)
91 		return NULL;
92 
93 	sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
94 	sta_info_pre_move_state(sta, IEEE80211_STA_ASSOC);
95 	sta_info_pre_move_state(sta, IEEE80211_STA_AUTHORIZED);
96 
97 	set_sta_flag(sta, WLAN_STA_WME);
98 
99 	return sta;
100 }
101 
102 /**
103  * mesh_set_ht_prot_mode - set correct HT protection mode
104  *
105  * Section 9.23.3.5 of IEEE 80211-2012 describes the protection rules for HT
106  * mesh STA in a MBSS. Three HT protection modes are supported for now, non-HT
107  * mixed mode, 20MHz-protection and no-protection mode. non-HT mixed mode is
108  * selected if any non-HT peers are present in our MBSS.  20MHz-protection mode
109  * is selected if all peers in our 20/40MHz MBSS support HT and atleast one
110  * HT20 peer is present. Otherwise no-protection mode is selected.
111  */
112 static u32 mesh_set_ht_prot_mode(struct ieee80211_sub_if_data *sdata)
113 {
114 	struct ieee80211_local *local = sdata->local;
115 	struct sta_info *sta;
116 	u32 changed = 0;
117 	u16 ht_opmode;
118 	bool non_ht_sta = false, ht20_sta = false;
119 
120 	if (local->_oper_channel_type == NL80211_CHAN_NO_HT)
121 		return 0;
122 
123 	rcu_read_lock();
124 	list_for_each_entry_rcu(sta, &local->sta_list, list) {
125 		if (sdata != sta->sdata ||
126 		    sta->plink_state != NL80211_PLINK_ESTAB)
127 			continue;
128 
129 		switch (sta->ch_type) {
130 		case NL80211_CHAN_NO_HT:
131 			mpl_dbg(sdata,
132 				"mesh_plink %pM: nonHT sta (%pM) is present\n",
133 				sdata->vif.addr, sta->sta.addr);
134 			non_ht_sta = true;
135 			goto out;
136 		case NL80211_CHAN_HT20:
137 			mpl_dbg(sdata,
138 				"mesh_plink %pM: HT20 sta (%pM) is present\n",
139 				sdata->vif.addr, sta->sta.addr);
140 			ht20_sta = true;
141 		default:
142 			break;
143 		}
144 	}
145 out:
146 	rcu_read_unlock();
147 
148 	if (non_ht_sta)
149 		ht_opmode = IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED;
150 	else if (ht20_sta && local->_oper_channel_type > NL80211_CHAN_HT20)
151 		ht_opmode = IEEE80211_HT_OP_MODE_PROTECTION_20MHZ;
152 	else
153 		ht_opmode = IEEE80211_HT_OP_MODE_PROTECTION_NONE;
154 
155 	if (sdata->vif.bss_conf.ht_operation_mode != ht_opmode) {
156 		sdata->vif.bss_conf.ht_operation_mode = ht_opmode;
157 		sdata->u.mesh.mshcfg.ht_opmode = ht_opmode;
158 		changed = BSS_CHANGED_HT;
159 		mpl_dbg(sdata,
160 			"mesh_plink %pM: protection mode changed to %d\n",
161 			sdata->vif.addr, ht_opmode);
162 	}
163 
164 	return changed;
165 }
166 
167 /**
168  * __mesh_plink_deactivate - deactivate mesh peer link
169  *
170  * @sta: mesh peer link to deactivate
171  *
172  * All mesh paths with this peer as next hop will be flushed
173  *
174  * Locking: the caller must hold sta->lock
175  */
176 static bool __mesh_plink_deactivate(struct sta_info *sta)
177 {
178 	struct ieee80211_sub_if_data *sdata = sta->sdata;
179 	bool deactivated = false;
180 
181 	if (sta->plink_state == NL80211_PLINK_ESTAB) {
182 		mesh_plink_dec_estab_count(sdata);
183 		deactivated = true;
184 	}
185 	sta->plink_state = NL80211_PLINK_BLOCKED;
186 	mesh_path_flush_by_nexthop(sta);
187 
188 	return deactivated;
189 }
190 
191 /**
192  * mesh_plink_deactivate - deactivate mesh peer link
193  *
194  * @sta: mesh peer link to deactivate
195  *
196  * All mesh paths with this peer as next hop will be flushed
197  */
198 void mesh_plink_deactivate(struct sta_info *sta)
199 {
200 	struct ieee80211_sub_if_data *sdata = sta->sdata;
201 	bool deactivated;
202 
203 	spin_lock_bh(&sta->lock);
204 	deactivated = __mesh_plink_deactivate(sta);
205 	sta->reason = cpu_to_le16(WLAN_REASON_MESH_PEER_CANCELED);
206 	mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
207 			    sta->sta.addr, sta->llid, sta->plid,
208 			    sta->reason);
209 	spin_unlock_bh(&sta->lock);
210 
211 	if (deactivated)
212 		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
213 }
214 
215 static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
216 		enum ieee80211_self_protected_actioncode action,
217 		u8 *da, __le16 llid, __le16 plid, __le16 reason) {
218 	struct ieee80211_local *local = sdata->local;
219 	struct sk_buff *skb;
220 	struct ieee80211_mgmt *mgmt;
221 	bool include_plid = false;
222 	u16 peering_proto = 0;
223 	u8 *pos, ie_len = 4;
224 	int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.self_prot) +
225 		      sizeof(mgmt->u.action.u.self_prot);
226 
227 	skb = dev_alloc_skb(local->tx_headroom +
228 			    hdr_len +
229 			    2 + /* capability info */
230 			    2 + /* AID */
231 			    2 + 8 + /* supported rates */
232 			    2 + (IEEE80211_MAX_SUPP_RATES - 8) +
233 			    2 + sdata->u.mesh.mesh_id_len +
234 			    2 + sizeof(struct ieee80211_meshconf_ie) +
235 			    2 + sizeof(struct ieee80211_ht_cap) +
236 			    2 + sizeof(struct ieee80211_ht_operation) +
237 			    2 + 8 + /* peering IE */
238 			    sdata->u.mesh.ie_len);
239 	if (!skb)
240 		return -1;
241 	skb_reserve(skb, local->tx_headroom);
242 	mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
243 	memset(mgmt, 0, hdr_len);
244 	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
245 					  IEEE80211_STYPE_ACTION);
246 	memcpy(mgmt->da, da, ETH_ALEN);
247 	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
248 	memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
249 	mgmt->u.action.category = WLAN_CATEGORY_SELF_PROTECTED;
250 	mgmt->u.action.u.self_prot.action_code = action;
251 
252 	if (action != WLAN_SP_MESH_PEERING_CLOSE) {
253 		/* capability info */
254 		pos = skb_put(skb, 2);
255 		memset(pos, 0, 2);
256 		if (action == WLAN_SP_MESH_PEERING_CONFIRM) {
257 			/* AID */
258 			pos = skb_put(skb, 2);
259 			memcpy(pos + 2, &plid, 2);
260 		}
261 		if (ieee80211_add_srates_ie(sdata, skb, true) ||
262 		    ieee80211_add_ext_srates_ie(sdata, skb, true) ||
263 		    mesh_add_rsn_ie(skb, sdata) ||
264 		    mesh_add_meshid_ie(skb, sdata) ||
265 		    mesh_add_meshconf_ie(skb, sdata))
266 			return -1;
267 	} else {	/* WLAN_SP_MESH_PEERING_CLOSE */
268 		if (mesh_add_meshid_ie(skb, sdata))
269 			return -1;
270 	}
271 
272 	/* Add Mesh Peering Management element */
273 	switch (action) {
274 	case WLAN_SP_MESH_PEERING_OPEN:
275 		break;
276 	case WLAN_SP_MESH_PEERING_CONFIRM:
277 		ie_len += 2;
278 		include_plid = true;
279 		break;
280 	case WLAN_SP_MESH_PEERING_CLOSE:
281 		if (plid) {
282 			ie_len += 2;
283 			include_plid = true;
284 		}
285 		ie_len += 2;	/* reason code */
286 		break;
287 	default:
288 		return -EINVAL;
289 	}
290 
291 	if (WARN_ON(skb_tailroom(skb) < 2 + ie_len))
292 		return -ENOMEM;
293 
294 	pos = skb_put(skb, 2 + ie_len);
295 	*pos++ = WLAN_EID_PEER_MGMT;
296 	*pos++ = ie_len;
297 	memcpy(pos, &peering_proto, 2);
298 	pos += 2;
299 	memcpy(pos, &llid, 2);
300 	pos += 2;
301 	if (include_plid) {
302 		memcpy(pos, &plid, 2);
303 		pos += 2;
304 	}
305 	if (action == WLAN_SP_MESH_PEERING_CLOSE) {
306 		memcpy(pos, &reason, 2);
307 		pos += 2;
308 	}
309 
310 	if (action != WLAN_SP_MESH_PEERING_CLOSE) {
311 		if (mesh_add_ht_cap_ie(skb, sdata) ||
312 		    mesh_add_ht_oper_ie(skb, sdata))
313 			return -1;
314 	}
315 
316 	if (mesh_add_vendor_ies(skb, sdata))
317 		return -1;
318 
319 	ieee80211_tx_skb(sdata, skb);
320 	return 0;
321 }
322 
323 /**
324  * mesh_peer_init - initialize new mesh peer and return resulting sta_info
325  *
326  * @sdata: local meshif
327  * @addr: peer's address
328  * @elems: IEs from beacon or mesh peering frame
329  *
330  * call under RCU
331  */
332 static struct sta_info *mesh_peer_init(struct ieee80211_sub_if_data *sdata,
333 				       u8 *addr,
334 				       struct ieee802_11_elems *elems)
335 {
336 	struct ieee80211_local *local = sdata->local;
337 	enum ieee80211_band band = local->oper_channel->band;
338 	struct ieee80211_supported_band *sband;
339 	u32 rates, basic_rates = 0;
340 	struct sta_info *sta;
341 	bool insert = false;
342 
343 	sband = local->hw.wiphy->bands[band];
344 	rates = ieee80211_sta_get_rates(local, elems, band, &basic_rates);
345 
346 	sta = sta_info_get(sdata, addr);
347 	if (!sta) {
348 		/* Userspace handles peer allocation when security is enabled */
349 		if (sdata->u.mesh.security & IEEE80211_MESH_SEC_AUTHED) {
350 			cfg80211_notify_new_peer_candidate(sdata->dev, addr,
351 							   elems->ie_start,
352 							   elems->total_len,
353 							   GFP_ATOMIC);
354 			return NULL;
355 		}
356 
357 		sta = mesh_plink_alloc(sdata, addr);
358 		if (!sta)
359 			return NULL;
360 		insert = true;
361 	}
362 
363 	spin_lock_bh(&sta->lock);
364 	sta->last_rx = jiffies;
365 	sta->sta.supp_rates[band] = rates;
366 	if (elems->ht_cap_elem &&
367 	    sdata->local->_oper_channel_type != NL80211_CHAN_NO_HT)
368 		ieee80211_ht_cap_ie_to_sta_ht_cap(sdata, sband,
369 						  elems->ht_cap_elem,
370 						  &sta->sta.ht_cap);
371 	else
372 		memset(&sta->sta.ht_cap, 0, sizeof(sta->sta.ht_cap));
373 
374 	if (elems->ht_operation) {
375 		if (!(elems->ht_operation->ht_param &
376 		      IEEE80211_HT_PARAM_CHAN_WIDTH_ANY))
377 			sta->sta.ht_cap.cap &=
378 					    ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
379 		sta->ch_type =
380 			ieee80211_ht_oper_to_channel_type(elems->ht_operation);
381 	}
382 
383 	rate_control_rate_init(sta);
384 	spin_unlock_bh(&sta->lock);
385 
386 	if (insert && sta_info_insert(sta))
387 		return NULL;
388 
389 	return sta;
390 }
391 
392 void mesh_neighbour_update(struct ieee80211_sub_if_data *sdata,
393 			   u8 *hw_addr,
394 			   struct ieee802_11_elems *elems)
395 {
396 	struct sta_info *sta;
397 
398 	rcu_read_lock();
399 	sta = mesh_peer_init(sdata, hw_addr, elems);
400 	if (!sta)
401 		goto out;
402 
403 	if (mesh_peer_accepts_plinks(elems) &&
404 	    sta->plink_state == NL80211_PLINK_LISTEN &&
405 	    sdata->u.mesh.accepting_plinks &&
406 	    sdata->u.mesh.mshcfg.auto_open_plinks &&
407 	    rssi_threshold_check(sta, sdata))
408 		mesh_plink_open(sta);
409 
410 out:
411 	rcu_read_unlock();
412 }
413 
414 static void mesh_plink_timer(unsigned long data)
415 {
416 	struct sta_info *sta;
417 	__le16 llid, plid, reason;
418 	struct ieee80211_sub_if_data *sdata;
419 
420 	/*
421 	 * This STA is valid because sta_info_destroy() will
422 	 * del_timer_sync() this timer after having made sure
423 	 * it cannot be readded (by deleting the plink.)
424 	 */
425 	sta = (struct sta_info *) data;
426 
427 	if (sta->sdata->local->quiescing) {
428 		sta->plink_timer_was_running = true;
429 		return;
430 	}
431 
432 	spin_lock_bh(&sta->lock);
433 	if (sta->ignore_plink_timer) {
434 		sta->ignore_plink_timer = false;
435 		spin_unlock_bh(&sta->lock);
436 		return;
437 	}
438 	mpl_dbg(sta->sdata,
439 		"Mesh plink timer for %pM fired on state %d\n",
440 		sta->sta.addr, sta->plink_state);
441 	reason = 0;
442 	llid = sta->llid;
443 	plid = sta->plid;
444 	sdata = sta->sdata;
445 
446 	switch (sta->plink_state) {
447 	case NL80211_PLINK_OPN_RCVD:
448 	case NL80211_PLINK_OPN_SNT:
449 		/* retry timer */
450 		if (sta->plink_retries < dot11MeshMaxRetries(sdata)) {
451 			u32 rand;
452 			mpl_dbg(sta->sdata,
453 				"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(sdata,
534 		"Mesh plink: starting establishment with %pM\n",
535 		sta->sta.addr);
536 
537 	return mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_OPEN,
538 				   sta->sta.addr, llid, 0, 0);
539 }
540 
541 void mesh_plink_block(struct sta_info *sta)
542 {
543 	struct ieee80211_sub_if_data *sdata = sta->sdata;
544 	bool deactivated;
545 
546 	spin_lock_bh(&sta->lock);
547 	deactivated = __mesh_plink_deactivate(sta);
548 	sta->plink_state = NL80211_PLINK_BLOCKED;
549 	spin_unlock_bh(&sta->lock);
550 
551 	if (deactivated)
552 		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
553 }
554 
555 
556 void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_mgmt *mgmt,
557 			 size_t len, struct ieee80211_rx_status *rx_status)
558 {
559 	struct ieee802_11_elems elems;
560 	struct sta_info *sta;
561 	enum plink_event event;
562 	enum ieee80211_self_protected_actioncode ftype;
563 	size_t baselen;
564 	bool matches_local = true;
565 	u8 ie_len;
566 	u8 *baseaddr;
567 	u32 changed = 0;
568 	__le16 plid, llid, reason;
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 
579 	/* need action_code, aux */
580 	if (len < IEEE80211_MIN_ACTION_SIZE + 3)
581 		return;
582 
583 	if (is_multicast_ether_addr(mgmt->da)) {
584 		mpl_dbg(sdata,
585 			"Mesh plink: ignore frame from multicast address\n");
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(sdata,
599 			"Mesh plink: missing necessary peer link ie\n");
600 		return;
601 	}
602 	if (elems.rsn_len &&
603 			sdata->u.mesh.security == IEEE80211_MESH_SEC_NONE) {
604 		mpl_dbg(sdata,
605 			"Mesh plink: can't establish link with secure peer\n");
606 		return;
607 	}
608 
609 	ftype = mgmt->u.action.u.self_prot.action_code;
610 	ie_len = elems.peering_len;
611 	if ((ftype == WLAN_SP_MESH_PEERING_OPEN && ie_len != 4) ||
612 	    (ftype == WLAN_SP_MESH_PEERING_CONFIRM && ie_len != 6) ||
613 	    (ftype == WLAN_SP_MESH_PEERING_CLOSE && ie_len != 6
614 							&& ie_len != 8)) {
615 		mpl_dbg(sdata,
616 			"Mesh plink: incorrect plink ie length %d %d\n",
617 			ftype, ie_len);
618 		return;
619 	}
620 
621 	if (ftype != WLAN_SP_MESH_PEERING_CLOSE &&
622 				(!elems.mesh_id || !elems.mesh_config)) {
623 		mpl_dbg(sdata, "Mesh plink: missing necessary ie\n");
624 		return;
625 	}
626 	/* Note the lines below are correct, the llid in the frame is the plid
627 	 * from the point of view of this host.
628 	 */
629 	memcpy(&plid, PLINK_GET_LLID(elems.peering), 2);
630 	if (ftype == WLAN_SP_MESH_PEERING_CONFIRM ||
631 	    (ftype == WLAN_SP_MESH_PEERING_CLOSE && ie_len == 8))
632 		memcpy(&llid, PLINK_GET_PLID(elems.peering), 2);
633 
634 	rcu_read_lock();
635 
636 	sta = sta_info_get(sdata, mgmt->sa);
637 	if (!sta && ftype != WLAN_SP_MESH_PEERING_OPEN) {
638 		mpl_dbg(sdata, "Mesh plink: cls or cnf from unknown peer\n");
639 		rcu_read_unlock();
640 		return;
641 	}
642 
643 	if (ftype == WLAN_SP_MESH_PEERING_OPEN &&
644 	    !rssi_threshold_check(sta, sdata)) {
645 		mpl_dbg(sdata, "Mesh plink: %pM does not meet rssi threshold\n",
646 			mgmt->sa);
647 		rcu_read_unlock();
648 		return;
649 	}
650 
651 	if (sta && !test_sta_flag(sta, WLAN_STA_AUTH)) {
652 		mpl_dbg(sdata, "Mesh plink: Action frame from non-authed peer\n");
653 		rcu_read_unlock();
654 		return;
655 	}
656 
657 	if (sta && sta->plink_state == NL80211_PLINK_BLOCKED) {
658 		rcu_read_unlock();
659 		return;
660 	}
661 
662 	/* Now we will figure out the appropriate event... */
663 	event = PLINK_UNDEFINED;
664 	if (ftype != WLAN_SP_MESH_PEERING_CLOSE &&
665 	    !mesh_matches_local(sdata, &elems)) {
666 		matches_local = false;
667 		switch (ftype) {
668 		case WLAN_SP_MESH_PEERING_OPEN:
669 			event = OPN_RJCT;
670 			break;
671 		case WLAN_SP_MESH_PEERING_CONFIRM:
672 			event = CNF_RJCT;
673 			break;
674 		default:
675 			break;
676 		}
677 	}
678 
679 	if (!sta && !matches_local) {
680 		rcu_read_unlock();
681 		reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
682 		llid = 0;
683 		mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
684 				    mgmt->sa, llid, plid, reason);
685 		return;
686 	} else if (!sta) {
687 		/* ftype == WLAN_SP_MESH_PEERING_OPEN */
688 		if (!mesh_plink_free_count(sdata)) {
689 			mpl_dbg(sdata, "Mesh plink error: no more free plinks\n");
690 			rcu_read_unlock();
691 			return;
692 		}
693 		event = OPN_ACPT;
694 	} else if (matches_local) {
695 		switch (ftype) {
696 		case WLAN_SP_MESH_PEERING_OPEN:
697 			if (!mesh_plink_free_count(sdata) ||
698 			    (sta->plid && sta->plid != plid))
699 				event = OPN_IGNR;
700 			else
701 				event = OPN_ACPT;
702 			break;
703 		case WLAN_SP_MESH_PEERING_CONFIRM:
704 			if (!mesh_plink_free_count(sdata) ||
705 			    (sta->llid != llid || sta->plid != plid))
706 				event = CNF_IGNR;
707 			else
708 				event = CNF_ACPT;
709 			break;
710 		case WLAN_SP_MESH_PEERING_CLOSE:
711 			if (sta->plink_state == NL80211_PLINK_ESTAB)
712 				/* Do not check for llid or plid. This does not
713 				 * follow the standard but since multiple plinks
714 				 * per sta are not supported, it is necessary in
715 				 * order to avoid a livelock when MP A sees an
716 				 * establish peer link to MP B but MP B does not
717 				 * see it. This can be caused by a timeout in
718 				 * B's peer link establishment or B beign
719 				 * restarted.
720 				 */
721 				event = CLS_ACPT;
722 			else if (sta->plid != plid)
723 				event = CLS_IGNR;
724 			else if (ie_len == 7 && sta->llid != llid)
725 				event = CLS_IGNR;
726 			else
727 				event = CLS_ACPT;
728 			break;
729 		default:
730 			mpl_dbg(sdata, "Mesh plink: unknown frame subtype\n");
731 			rcu_read_unlock();
732 			return;
733 		}
734 	}
735 
736 	if (event == OPN_ACPT) {
737 		/* allocate sta entry if necessary and update info */
738 		sta = mesh_peer_init(sdata, mgmt->sa, &elems);
739 		if (!sta) {
740 			mpl_dbg(sdata, "Mesh plink: failed to init peer!\n");
741 			rcu_read_unlock();
742 			return;
743 		}
744 	}
745 
746 	mpl_dbg(sdata,
747 		"Mesh plink (peer, state, llid, plid, event): %pM %s %d %d %d\n",
748 		mgmt->sa, mplstates[sta->plink_state],
749 		le16_to_cpu(sta->llid), le16_to_cpu(sta->plid),
750 		event);
751 	reason = 0;
752 	spin_lock_bh(&sta->lock);
753 	switch (sta->plink_state) {
754 		/* spin_unlock as soon as state is updated at each case */
755 	case NL80211_PLINK_LISTEN:
756 		switch (event) {
757 		case CLS_ACPT:
758 			mesh_plink_fsm_restart(sta);
759 			spin_unlock_bh(&sta->lock);
760 			break;
761 		case OPN_ACPT:
762 			sta->plink_state = NL80211_PLINK_OPN_RCVD;
763 			sta->plid = plid;
764 			get_random_bytes(&llid, 2);
765 			sta->llid = llid;
766 			mesh_plink_timer_set(sta, dot11MeshRetryTimeout(sdata));
767 			spin_unlock_bh(&sta->lock);
768 			mesh_plink_frame_tx(sdata,
769 					    WLAN_SP_MESH_PEERING_OPEN,
770 					    sta->sta.addr, llid, 0, 0);
771 			mesh_plink_frame_tx(sdata,
772 					    WLAN_SP_MESH_PEERING_CONFIRM,
773 					    sta->sta.addr, llid, plid, 0);
774 			break;
775 		default:
776 			spin_unlock_bh(&sta->lock);
777 			break;
778 		}
779 		break;
780 
781 	case NL80211_PLINK_OPN_SNT:
782 		switch (event) {
783 		case OPN_RJCT:
784 		case CNF_RJCT:
785 			reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
786 		case CLS_ACPT:
787 			if (!reason)
788 				reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
789 			sta->reason = reason;
790 			sta->plink_state = NL80211_PLINK_HOLDING;
791 			if (!mod_plink_timer(sta,
792 					     dot11MeshHoldingTimeout(sdata)))
793 				sta->ignore_plink_timer = true;
794 
795 			llid = sta->llid;
796 			spin_unlock_bh(&sta->lock);
797 			mesh_plink_frame_tx(sdata,
798 					    WLAN_SP_MESH_PEERING_CLOSE,
799 					    sta->sta.addr, llid, plid, reason);
800 			break;
801 		case OPN_ACPT:
802 			/* retry timer is left untouched */
803 			sta->plink_state = NL80211_PLINK_OPN_RCVD;
804 			sta->plid = plid;
805 			llid = sta->llid;
806 			spin_unlock_bh(&sta->lock);
807 			mesh_plink_frame_tx(sdata,
808 					    WLAN_SP_MESH_PEERING_CONFIRM,
809 					    sta->sta.addr, llid, plid, 0);
810 			break;
811 		case CNF_ACPT:
812 			sta->plink_state = NL80211_PLINK_CNF_RCVD;
813 			if (!mod_plink_timer(sta,
814 					     dot11MeshConfirmTimeout(sdata)))
815 				sta->ignore_plink_timer = true;
816 
817 			spin_unlock_bh(&sta->lock);
818 			break;
819 		default:
820 			spin_unlock_bh(&sta->lock);
821 			break;
822 		}
823 		break;
824 
825 	case NL80211_PLINK_OPN_RCVD:
826 		switch (event) {
827 		case OPN_RJCT:
828 		case CNF_RJCT:
829 			reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
830 		case CLS_ACPT:
831 			if (!reason)
832 				reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
833 			sta->reason = reason;
834 			sta->plink_state = NL80211_PLINK_HOLDING;
835 			if (!mod_plink_timer(sta,
836 					     dot11MeshHoldingTimeout(sdata)))
837 				sta->ignore_plink_timer = true;
838 
839 			llid = sta->llid;
840 			spin_unlock_bh(&sta->lock);
841 			mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
842 					    sta->sta.addr, llid, plid, reason);
843 			break;
844 		case OPN_ACPT:
845 			llid = sta->llid;
846 			spin_unlock_bh(&sta->lock);
847 			mesh_plink_frame_tx(sdata,
848 					    WLAN_SP_MESH_PEERING_CONFIRM,
849 					    sta->sta.addr, llid, plid, 0);
850 			break;
851 		case CNF_ACPT:
852 			del_timer(&sta->plink_timer);
853 			sta->plink_state = NL80211_PLINK_ESTAB;
854 			spin_unlock_bh(&sta->lock);
855 			mesh_plink_inc_estab_count(sdata);
856 			changed |= mesh_set_ht_prot_mode(sdata);
857 			changed |= BSS_CHANGED_BEACON;
858 			mpl_dbg(sdata, "Mesh plink with %pM ESTABLISHED\n",
859 				sta->sta.addr);
860 			break;
861 		default:
862 			spin_unlock_bh(&sta->lock);
863 			break;
864 		}
865 		break;
866 
867 	case NL80211_PLINK_CNF_RCVD:
868 		switch (event) {
869 		case OPN_RJCT:
870 		case CNF_RJCT:
871 			reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
872 		case CLS_ACPT:
873 			if (!reason)
874 				reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
875 			sta->reason = reason;
876 			sta->plink_state = NL80211_PLINK_HOLDING;
877 			if (!mod_plink_timer(sta,
878 					     dot11MeshHoldingTimeout(sdata)))
879 				sta->ignore_plink_timer = true;
880 
881 			llid = sta->llid;
882 			spin_unlock_bh(&sta->lock);
883 			mesh_plink_frame_tx(sdata,
884 					    WLAN_SP_MESH_PEERING_CLOSE,
885 					    sta->sta.addr, llid, plid, reason);
886 			break;
887 		case OPN_ACPT:
888 			del_timer(&sta->plink_timer);
889 			sta->plink_state = NL80211_PLINK_ESTAB;
890 			spin_unlock_bh(&sta->lock);
891 			mesh_plink_inc_estab_count(sdata);
892 			changed |= mesh_set_ht_prot_mode(sdata);
893 			changed |= BSS_CHANGED_BEACON;
894 			mpl_dbg(sdata, "Mesh plink with %pM ESTABLISHED\n",
895 				sta->sta.addr);
896 			mesh_plink_frame_tx(sdata,
897 					    WLAN_SP_MESH_PEERING_CONFIRM,
898 					    sta->sta.addr, llid, plid, 0);
899 			break;
900 		default:
901 			spin_unlock_bh(&sta->lock);
902 			break;
903 		}
904 		break;
905 
906 	case NL80211_PLINK_ESTAB:
907 		switch (event) {
908 		case CLS_ACPT:
909 			reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
910 			sta->reason = reason;
911 			__mesh_plink_deactivate(sta);
912 			sta->plink_state = NL80211_PLINK_HOLDING;
913 			llid = sta->llid;
914 			mod_plink_timer(sta, dot11MeshHoldingTimeout(sdata));
915 			spin_unlock_bh(&sta->lock);
916 			changed |= mesh_set_ht_prot_mode(sdata);
917 			changed |= BSS_CHANGED_BEACON;
918 			mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
919 					    sta->sta.addr, llid, plid, reason);
920 			break;
921 		case OPN_ACPT:
922 			llid = sta->llid;
923 			spin_unlock_bh(&sta->lock);
924 			mesh_plink_frame_tx(sdata,
925 					    WLAN_SP_MESH_PEERING_CONFIRM,
926 					    sta->sta.addr, llid, plid, 0);
927 			break;
928 		default:
929 			spin_unlock_bh(&sta->lock);
930 			break;
931 		}
932 		break;
933 	case NL80211_PLINK_HOLDING:
934 		switch (event) {
935 		case CLS_ACPT:
936 			if (del_timer(&sta->plink_timer))
937 				sta->ignore_plink_timer = 1;
938 			mesh_plink_fsm_restart(sta);
939 			spin_unlock_bh(&sta->lock);
940 			break;
941 		case OPN_ACPT:
942 		case CNF_ACPT:
943 		case OPN_RJCT:
944 		case CNF_RJCT:
945 			llid = sta->llid;
946 			reason = sta->reason;
947 			spin_unlock_bh(&sta->lock);
948 			mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
949 					    sta->sta.addr, llid, plid, reason);
950 			break;
951 		default:
952 			spin_unlock_bh(&sta->lock);
953 		}
954 		break;
955 	default:
956 		/* should not get here, PLINK_BLOCKED is dealt with at the
957 		 * beginning of the function
958 		 */
959 		spin_unlock_bh(&sta->lock);
960 		break;
961 	}
962 
963 	rcu_read_unlock();
964 
965 	if (changed)
966 		ieee80211_bss_info_change_notify(sdata, changed);
967 }
968