xref: /openbmc/linux/net/mac80211/scan.c (revision 337600fb)
1 /*
2  * Scanning implementation
3  *
4  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
5  * Copyright 2004, Instant802 Networks, Inc.
6  * Copyright 2005, Devicescape Software, Inc.
7  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
8  * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
9  * Copyright 2013-2015  Intel Mobile Communications GmbH
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License version 2 as
13  * published by the Free Software Foundation.
14  */
15 
16 #include <linux/if_arp.h>
17 #include <linux/etherdevice.h>
18 #include <linux/rtnetlink.h>
19 #include <net/sch_generic.h>
20 #include <linux/slab.h>
21 #include <linux/export.h>
22 #include <net/mac80211.h>
23 
24 #include "ieee80211_i.h"
25 #include "driver-ops.h"
26 #include "mesh.h"
27 
28 #define IEEE80211_PROBE_DELAY (HZ / 33)
29 #define IEEE80211_CHANNEL_TIME (HZ / 33)
30 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 9)
31 
32 void ieee80211_rx_bss_put(struct ieee80211_local *local,
33 			  struct ieee80211_bss *bss)
34 {
35 	if (!bss)
36 		return;
37 	cfg80211_put_bss(local->hw.wiphy,
38 			 container_of((void *)bss, struct cfg80211_bss, priv));
39 }
40 
41 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
42 {
43 	u8 qos_info;
44 
45 	if (elems->wmm_info && elems->wmm_info_len == 7
46 	    && elems->wmm_info[5] == 1)
47 		qos_info = elems->wmm_info[6];
48 	else if (elems->wmm_param && elems->wmm_param_len == 24
49 		 && elems->wmm_param[5] == 1)
50 		qos_info = elems->wmm_param[6];
51 	else
52 		/* no valid wmm information or parameter element found */
53 		return false;
54 
55 	return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
56 }
57 
58 struct ieee80211_bss *
59 ieee80211_bss_info_update(struct ieee80211_local *local,
60 			  struct ieee80211_rx_status *rx_status,
61 			  struct ieee80211_mgmt *mgmt, size_t len,
62 			  struct ieee802_11_elems *elems,
63 			  struct ieee80211_channel *channel)
64 {
65 	bool beacon = ieee80211_is_beacon(mgmt->frame_control);
66 	struct cfg80211_bss *cbss;
67 	struct ieee80211_bss *bss;
68 	int clen, srlen;
69 	struct cfg80211_inform_bss bss_meta = {};
70 	bool signal_valid;
71 
72 	if (ieee80211_hw_check(&local->hw, SIGNAL_DBM))
73 		bss_meta.signal = rx_status->signal * 100;
74 	else if (ieee80211_hw_check(&local->hw, SIGNAL_UNSPEC))
75 		bss_meta.signal = (rx_status->signal * 100) / local->hw.max_signal;
76 
77 	bss_meta.scan_width = NL80211_BSS_CHAN_WIDTH_20;
78 	if (rx_status->flag & RX_FLAG_5MHZ)
79 		bss_meta.scan_width = NL80211_BSS_CHAN_WIDTH_5;
80 	if (rx_status->flag & RX_FLAG_10MHZ)
81 		bss_meta.scan_width = NL80211_BSS_CHAN_WIDTH_10;
82 
83 	bss_meta.chan = channel;
84 	cbss = cfg80211_inform_bss_frame_data(local->hw.wiphy, &bss_meta,
85 					      mgmt, len, GFP_ATOMIC);
86 	if (!cbss)
87 		return NULL;
88 	/* In case the signal is invalid update the status */
89 	signal_valid = abs(channel->center_freq - cbss->channel->center_freq)
90 		<= local->hw.wiphy->max_adj_channel_rssi_comp;
91 	if (!signal_valid)
92 		rx_status->flag |= RX_FLAG_NO_SIGNAL_VAL;
93 
94 	bss = (void *)cbss->priv;
95 
96 	if (beacon)
97 		bss->device_ts_beacon = rx_status->device_timestamp;
98 	else
99 		bss->device_ts_presp = rx_status->device_timestamp;
100 
101 	if (elems->parse_error) {
102 		if (beacon)
103 			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_BEACON;
104 		else
105 			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_PROBE_RESP;
106 	} else {
107 		if (beacon)
108 			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_BEACON;
109 		else
110 			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_PROBE_RESP;
111 	}
112 
113 	/* save the ERP value so that it is available at association time */
114 	if (elems->erp_info && (!elems->parse_error ||
115 				!(bss->valid_data & IEEE80211_BSS_VALID_ERP))) {
116 		bss->erp_value = elems->erp_info[0];
117 		bss->has_erp_value = true;
118 		if (!elems->parse_error)
119 			bss->valid_data |= IEEE80211_BSS_VALID_ERP;
120 	}
121 
122 	/* replace old supported rates if we get new values */
123 	if (!elems->parse_error ||
124 	    !(bss->valid_data & IEEE80211_BSS_VALID_RATES)) {
125 		srlen = 0;
126 		if (elems->supp_rates) {
127 			clen = IEEE80211_MAX_SUPP_RATES;
128 			if (clen > elems->supp_rates_len)
129 				clen = elems->supp_rates_len;
130 			memcpy(bss->supp_rates, elems->supp_rates, clen);
131 			srlen += clen;
132 		}
133 		if (elems->ext_supp_rates) {
134 			clen = IEEE80211_MAX_SUPP_RATES - srlen;
135 			if (clen > elems->ext_supp_rates_len)
136 				clen = elems->ext_supp_rates_len;
137 			memcpy(bss->supp_rates + srlen, elems->ext_supp_rates,
138 			       clen);
139 			srlen += clen;
140 		}
141 		if (srlen) {
142 			bss->supp_rates_len = srlen;
143 			if (!elems->parse_error)
144 				bss->valid_data |= IEEE80211_BSS_VALID_RATES;
145 		}
146 	}
147 
148 	if (!elems->parse_error ||
149 	    !(bss->valid_data & IEEE80211_BSS_VALID_WMM)) {
150 		bss->wmm_used = elems->wmm_param || elems->wmm_info;
151 		bss->uapsd_supported = is_uapsd_supported(elems);
152 		if (!elems->parse_error)
153 			bss->valid_data |= IEEE80211_BSS_VALID_WMM;
154 	}
155 
156 	if (beacon) {
157 		struct ieee80211_supported_band *sband =
158 			local->hw.wiphy->bands[rx_status->band];
159 		if (!(rx_status->flag & RX_FLAG_HT) &&
160 		    !(rx_status->flag & RX_FLAG_VHT))
161 			bss->beacon_rate =
162 				&sband->bitrates[rx_status->rate_idx];
163 	}
164 
165 	return bss;
166 }
167 
168 void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
169 {
170 	struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
171 	struct ieee80211_sub_if_data *sdata1, *sdata2;
172 	struct ieee80211_mgmt *mgmt = (void *)skb->data;
173 	struct ieee80211_bss *bss;
174 	u8 *elements;
175 	struct ieee80211_channel *channel;
176 	size_t baselen;
177 	struct ieee802_11_elems elems;
178 
179 	if (skb->len < 24 ||
180 	    (!ieee80211_is_probe_resp(mgmt->frame_control) &&
181 	     !ieee80211_is_beacon(mgmt->frame_control)))
182 		return;
183 
184 	sdata1 = rcu_dereference(local->scan_sdata);
185 	sdata2 = rcu_dereference(local->sched_scan_sdata);
186 
187 	if (likely(!sdata1 && !sdata2))
188 		return;
189 
190 	if (ieee80211_is_probe_resp(mgmt->frame_control)) {
191 		struct cfg80211_scan_request *scan_req;
192 		struct cfg80211_sched_scan_request *sched_scan_req;
193 
194 		scan_req = rcu_dereference(local->scan_req);
195 		sched_scan_req = rcu_dereference(local->sched_scan_req);
196 
197 		/* ignore ProbeResp to foreign address unless scanning
198 		 * with randomised address
199 		 */
200 		if (!(sdata1 &&
201 		      (ether_addr_equal(mgmt->da, sdata1->vif.addr) ||
202 		       scan_req->flags & NL80211_SCAN_FLAG_RANDOM_ADDR)) &&
203 		    !(sdata2 &&
204 		      (ether_addr_equal(mgmt->da, sdata2->vif.addr) ||
205 		       sched_scan_req->flags & NL80211_SCAN_FLAG_RANDOM_ADDR)))
206 			return;
207 
208 		elements = mgmt->u.probe_resp.variable;
209 		baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
210 	} else {
211 		baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
212 		elements = mgmt->u.beacon.variable;
213 	}
214 
215 	if (baselen > skb->len)
216 		return;
217 
218 	ieee802_11_parse_elems(elements, skb->len - baselen, false, &elems);
219 
220 	channel = ieee80211_get_channel(local->hw.wiphy, rx_status->freq);
221 
222 	if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
223 		return;
224 
225 	bss = ieee80211_bss_info_update(local, rx_status,
226 					mgmt, skb->len, &elems,
227 					channel);
228 	if (bss)
229 		ieee80211_rx_bss_put(local, bss);
230 }
231 
232 static void
233 ieee80211_prepare_scan_chandef(struct cfg80211_chan_def *chandef,
234 			       enum nl80211_bss_scan_width scan_width)
235 {
236 	memset(chandef, 0, sizeof(*chandef));
237 	switch (scan_width) {
238 	case NL80211_BSS_CHAN_WIDTH_5:
239 		chandef->width = NL80211_CHAN_WIDTH_5;
240 		break;
241 	case NL80211_BSS_CHAN_WIDTH_10:
242 		chandef->width = NL80211_CHAN_WIDTH_10;
243 		break;
244 	default:
245 		chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
246 		break;
247 	}
248 }
249 
250 /* return false if no more work */
251 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
252 {
253 	struct cfg80211_scan_request *req;
254 	struct cfg80211_chan_def chandef;
255 	u8 bands_used = 0;
256 	int i, ielen, n_chans;
257 
258 	req = rcu_dereference_protected(local->scan_req,
259 					lockdep_is_held(&local->mtx));
260 
261 	if (test_bit(SCAN_HW_CANCELLED, &local->scanning))
262 		return false;
263 
264 	if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) {
265 		for (i = 0; i < req->n_channels; i++) {
266 			local->hw_scan_req->req.channels[i] = req->channels[i];
267 			bands_used |= BIT(req->channels[i]->band);
268 		}
269 
270 		n_chans = req->n_channels;
271 	} else {
272 		do {
273 			if (local->hw_scan_band == IEEE80211_NUM_BANDS)
274 				return false;
275 
276 			n_chans = 0;
277 
278 			for (i = 0; i < req->n_channels; i++) {
279 				if (req->channels[i]->band !=
280 				    local->hw_scan_band)
281 					continue;
282 				local->hw_scan_req->req.channels[n_chans] =
283 							req->channels[i];
284 				n_chans++;
285 				bands_used |= BIT(req->channels[i]->band);
286 			}
287 
288 			local->hw_scan_band++;
289 		} while (!n_chans);
290 	}
291 
292 	local->hw_scan_req->req.n_channels = n_chans;
293 	ieee80211_prepare_scan_chandef(&chandef, req->scan_width);
294 
295 	ielen = ieee80211_build_preq_ies(local,
296 					 (u8 *)local->hw_scan_req->req.ie,
297 					 local->hw_scan_ies_bufsize,
298 					 &local->hw_scan_req->ies,
299 					 req->ie, req->ie_len,
300 					 bands_used, req->rates, &chandef);
301 	local->hw_scan_req->req.ie_len = ielen;
302 	local->hw_scan_req->req.no_cck = req->no_cck;
303 	ether_addr_copy(local->hw_scan_req->req.mac_addr, req->mac_addr);
304 	ether_addr_copy(local->hw_scan_req->req.mac_addr_mask,
305 			req->mac_addr_mask);
306 
307 	return true;
308 }
309 
310 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
311 {
312 	struct ieee80211_local *local = hw_to_local(hw);
313 	bool hw_scan = local->ops->hw_scan;
314 	bool was_scanning = local->scanning;
315 	struct cfg80211_scan_request *scan_req;
316 	struct ieee80211_sub_if_data *scan_sdata;
317 
318 	lockdep_assert_held(&local->mtx);
319 
320 	/*
321 	 * It's ok to abort a not-yet-running scan (that
322 	 * we have one at all will be verified by checking
323 	 * local->scan_req next), but not to complete it
324 	 * successfully.
325 	 */
326 	if (WARN_ON(!local->scanning && !aborted))
327 		aborted = true;
328 
329 	if (WARN_ON(!local->scan_req))
330 		return;
331 
332 	if (hw_scan && !aborted &&
333 	    !ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS) &&
334 	    ieee80211_prep_hw_scan(local)) {
335 		int rc;
336 
337 		rc = drv_hw_scan(local,
338 			rcu_dereference_protected(local->scan_sdata,
339 						  lockdep_is_held(&local->mtx)),
340 			local->hw_scan_req);
341 
342 		if (rc == 0)
343 			return;
344 	}
345 
346 	kfree(local->hw_scan_req);
347 	local->hw_scan_req = NULL;
348 
349 	scan_req = rcu_dereference_protected(local->scan_req,
350 					     lockdep_is_held(&local->mtx));
351 
352 	if (scan_req != local->int_scan_req)
353 		cfg80211_scan_done(scan_req, aborted);
354 	RCU_INIT_POINTER(local->scan_req, NULL);
355 
356 	scan_sdata = rcu_dereference_protected(local->scan_sdata,
357 					       lockdep_is_held(&local->mtx));
358 	RCU_INIT_POINTER(local->scan_sdata, NULL);
359 
360 	local->scanning = 0;
361 	local->scan_chandef.chan = NULL;
362 
363 	/* Set power back to normal operating levels. */
364 	ieee80211_hw_config(local, 0);
365 
366 	if (!hw_scan) {
367 		ieee80211_configure_filter(local);
368 		drv_sw_scan_complete(local, scan_sdata);
369 		ieee80211_offchannel_return(local);
370 	}
371 
372 	ieee80211_recalc_idle(local);
373 
374 	ieee80211_mlme_notify_scan_completed(local);
375 	ieee80211_ibss_notify_scan_completed(local);
376 	ieee80211_mesh_notify_scan_completed(local);
377 	if (was_scanning)
378 		ieee80211_start_next_roc(local);
379 }
380 
381 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
382 {
383 	struct ieee80211_local *local = hw_to_local(hw);
384 
385 	trace_api_scan_completed(local, aborted);
386 
387 	set_bit(SCAN_COMPLETED, &local->scanning);
388 	if (aborted)
389 		set_bit(SCAN_ABORTED, &local->scanning);
390 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
391 }
392 EXPORT_SYMBOL(ieee80211_scan_completed);
393 
394 static int ieee80211_start_sw_scan(struct ieee80211_local *local,
395 				   struct ieee80211_sub_if_data *sdata)
396 {
397 	/* Software scan is not supported in multi-channel cases */
398 	if (local->use_chanctx)
399 		return -EOPNOTSUPP;
400 
401 	/*
402 	 * Hardware/driver doesn't support hw_scan, so use software
403 	 * scanning instead. First send a nullfunc frame with power save
404 	 * bit on so that AP will buffer the frames for us while we are not
405 	 * listening, then send probe requests to each channel and wait for
406 	 * the responses. After all channels are scanned, tune back to the
407 	 * original channel and send a nullfunc frame with power save bit
408 	 * off to trigger the AP to send us all the buffered frames.
409 	 *
410 	 * Note that while local->sw_scanning is true everything else but
411 	 * nullfunc frames and probe requests will be dropped in
412 	 * ieee80211_tx_h_check_assoc().
413 	 */
414 	drv_sw_scan_start(local, sdata, local->scan_addr);
415 
416 	local->leave_oper_channel_time = jiffies;
417 	local->next_scan_state = SCAN_DECISION;
418 	local->scan_channel_idx = 0;
419 
420 	ieee80211_offchannel_stop_vifs(local);
421 
422 	/* ensure nullfunc is transmitted before leaving operating channel */
423 	ieee80211_flush_queues(local, NULL, false);
424 
425 	ieee80211_configure_filter(local);
426 
427 	/* We need to set power level at maximum rate for scanning. */
428 	ieee80211_hw_config(local, 0);
429 
430 	ieee80211_queue_delayed_work(&local->hw,
431 				     &local->scan_work, 0);
432 
433 	return 0;
434 }
435 
436 static bool ieee80211_can_scan(struct ieee80211_local *local,
437 			       struct ieee80211_sub_if_data *sdata)
438 {
439 	if (ieee80211_is_radar_required(local))
440 		return false;
441 
442 	if (!list_empty(&local->roc_list))
443 		return false;
444 
445 	if (sdata->vif.type == NL80211_IFTYPE_STATION &&
446 	    sdata->u.mgd.flags & IEEE80211_STA_CONNECTION_POLL)
447 		return false;
448 
449 	return true;
450 }
451 
452 void ieee80211_run_deferred_scan(struct ieee80211_local *local)
453 {
454 	lockdep_assert_held(&local->mtx);
455 
456 	if (!local->scan_req || local->scanning)
457 		return;
458 
459 	if (!ieee80211_can_scan(local,
460 				rcu_dereference_protected(
461 					local->scan_sdata,
462 					lockdep_is_held(&local->mtx))))
463 		return;
464 
465 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
466 				     round_jiffies_relative(0));
467 }
468 
469 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
470 					    unsigned long *next_delay)
471 {
472 	int i;
473 	struct ieee80211_sub_if_data *sdata;
474 	struct cfg80211_scan_request *scan_req;
475 	enum ieee80211_band band = local->hw.conf.chandef.chan->band;
476 	u32 tx_flags;
477 
478 	scan_req = rcu_dereference_protected(local->scan_req,
479 					     lockdep_is_held(&local->mtx));
480 
481 	tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
482 	if (scan_req->no_cck)
483 		tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;
484 
485 	sdata = rcu_dereference_protected(local->scan_sdata,
486 					  lockdep_is_held(&local->mtx));
487 
488 	for (i = 0; i < scan_req->n_ssids; i++)
489 		ieee80211_send_probe_req(
490 			sdata, local->scan_addr, NULL,
491 			scan_req->ssids[i].ssid, scan_req->ssids[i].ssid_len,
492 			scan_req->ie, scan_req->ie_len,
493 			scan_req->rates[band], false,
494 			tx_flags, local->hw.conf.chandef.chan, true);
495 
496 	/*
497 	 * After sending probe requests, wait for probe responses
498 	 * on the channel.
499 	 */
500 	*next_delay = IEEE80211_CHANNEL_TIME;
501 	local->next_scan_state = SCAN_DECISION;
502 }
503 
504 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
505 				  struct cfg80211_scan_request *req)
506 {
507 	struct ieee80211_local *local = sdata->local;
508 	int rc;
509 
510 	lockdep_assert_held(&local->mtx);
511 
512 	if (local->scan_req || ieee80211_is_radar_required(local))
513 		return -EBUSY;
514 
515 	if (!ieee80211_can_scan(local, sdata)) {
516 		/* wait for the work to finish/time out */
517 		rcu_assign_pointer(local->scan_req, req);
518 		rcu_assign_pointer(local->scan_sdata, sdata);
519 		return 0;
520 	}
521 
522 	if (local->ops->hw_scan) {
523 		u8 *ies;
524 
525 		local->hw_scan_ies_bufsize = local->scan_ies_len + req->ie_len;
526 
527 		if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) {
528 			int i, n_bands = 0;
529 			u8 bands_counted = 0;
530 
531 			for (i = 0; i < req->n_channels; i++) {
532 				if (bands_counted & BIT(req->channels[i]->band))
533 					continue;
534 				bands_counted |= BIT(req->channels[i]->band);
535 				n_bands++;
536 			}
537 
538 			local->hw_scan_ies_bufsize *= n_bands;
539 		}
540 
541 		local->hw_scan_req = kmalloc(
542 				sizeof(*local->hw_scan_req) +
543 				req->n_channels * sizeof(req->channels[0]) +
544 				local->hw_scan_ies_bufsize, GFP_KERNEL);
545 		if (!local->hw_scan_req)
546 			return -ENOMEM;
547 
548 		local->hw_scan_req->req.ssids = req->ssids;
549 		local->hw_scan_req->req.n_ssids = req->n_ssids;
550 		ies = (u8 *)local->hw_scan_req +
551 			sizeof(*local->hw_scan_req) +
552 			req->n_channels * sizeof(req->channels[0]);
553 		local->hw_scan_req->req.ie = ies;
554 		local->hw_scan_req->req.flags = req->flags;
555 
556 		local->hw_scan_band = 0;
557 
558 		/*
559 		 * After allocating local->hw_scan_req, we must
560 		 * go through until ieee80211_prep_hw_scan(), so
561 		 * anything that might be changed here and leave
562 		 * this function early must not go after this
563 		 * allocation.
564 		 */
565 	}
566 
567 	rcu_assign_pointer(local->scan_req, req);
568 	rcu_assign_pointer(local->scan_sdata, sdata);
569 
570 	if (req->flags & NL80211_SCAN_FLAG_RANDOM_ADDR)
571 		get_random_mask_addr(local->scan_addr,
572 				     req->mac_addr,
573 				     req->mac_addr_mask);
574 	else
575 		memcpy(local->scan_addr, sdata->vif.addr, ETH_ALEN);
576 
577 	if (local->ops->hw_scan) {
578 		__set_bit(SCAN_HW_SCANNING, &local->scanning);
579 	} else if ((req->n_channels == 1) &&
580 		   (req->channels[0] == local->_oper_chandef.chan)) {
581 		/*
582 		 * If we are scanning only on the operating channel
583 		 * then we do not need to stop normal activities
584 		 */
585 		unsigned long next_delay;
586 
587 		__set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
588 
589 		ieee80211_recalc_idle(local);
590 
591 		/* Notify driver scan is starting, keep order of operations
592 		 * same as normal software scan, in case that matters. */
593 		drv_sw_scan_start(local, sdata, local->scan_addr);
594 
595 		ieee80211_configure_filter(local); /* accept probe-responses */
596 
597 		/* We need to ensure power level is at max for scanning. */
598 		ieee80211_hw_config(local, 0);
599 
600 		if ((req->channels[0]->flags & (IEEE80211_CHAN_NO_IR |
601 						IEEE80211_CHAN_RADAR)) ||
602 		    !req->n_ssids) {
603 			next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
604 		} else {
605 			ieee80211_scan_state_send_probe(local, &next_delay);
606 			next_delay = IEEE80211_CHANNEL_TIME;
607 		}
608 
609 		/* Now, just wait a bit and we are all done! */
610 		ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
611 					     next_delay);
612 		return 0;
613 	} else {
614 		/* Do normal software scan */
615 		__set_bit(SCAN_SW_SCANNING, &local->scanning);
616 	}
617 
618 	ieee80211_recalc_idle(local);
619 
620 	if (local->ops->hw_scan) {
621 		WARN_ON(!ieee80211_prep_hw_scan(local));
622 		rc = drv_hw_scan(local, sdata, local->hw_scan_req);
623 	} else {
624 		rc = ieee80211_start_sw_scan(local, sdata);
625 	}
626 
627 	if (rc) {
628 		kfree(local->hw_scan_req);
629 		local->hw_scan_req = NULL;
630 		local->scanning = 0;
631 
632 		ieee80211_recalc_idle(local);
633 
634 		local->scan_req = NULL;
635 		RCU_INIT_POINTER(local->scan_sdata, NULL);
636 	}
637 
638 	return rc;
639 }
640 
641 static unsigned long
642 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
643 {
644 	/*
645 	 * TODO: channel switching also consumes quite some time,
646 	 * add that delay as well to get a better estimation
647 	 */
648 	if (chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR))
649 		return IEEE80211_PASSIVE_CHANNEL_TIME;
650 	return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
651 }
652 
653 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
654 					  unsigned long *next_delay)
655 {
656 	bool associated = false;
657 	bool tx_empty = true;
658 	bool bad_latency;
659 	struct ieee80211_sub_if_data *sdata;
660 	struct ieee80211_channel *next_chan;
661 	enum mac80211_scan_state next_scan_state;
662 	struct cfg80211_scan_request *scan_req;
663 
664 	/*
665 	 * check if at least one STA interface is associated,
666 	 * check if at least one STA interface has pending tx frames
667 	 * and grab the lowest used beacon interval
668 	 */
669 	mutex_lock(&local->iflist_mtx);
670 	list_for_each_entry(sdata, &local->interfaces, list) {
671 		if (!ieee80211_sdata_running(sdata))
672 			continue;
673 
674 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
675 			if (sdata->u.mgd.associated) {
676 				associated = true;
677 
678 				if (!qdisc_all_tx_empty(sdata->dev)) {
679 					tx_empty = false;
680 					break;
681 				}
682 			}
683 		}
684 	}
685 	mutex_unlock(&local->iflist_mtx);
686 
687 	scan_req = rcu_dereference_protected(local->scan_req,
688 					     lockdep_is_held(&local->mtx));
689 
690 	next_chan = scan_req->channels[local->scan_channel_idx];
691 
692 	/*
693 	 * we're currently scanning a different channel, let's
694 	 * see if we can scan another channel without interfering
695 	 * with the current traffic situation.
696 	 *
697 	 * Keep good latency, do not stay off-channel more than 125 ms.
698 	 */
699 
700 	bad_latency = time_after(jiffies +
701 				 ieee80211_scan_get_channel_time(next_chan),
702 				 local->leave_oper_channel_time + HZ / 8);
703 
704 	if (associated && !tx_empty) {
705 		if (scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
706 			next_scan_state = SCAN_ABORT;
707 		else
708 			next_scan_state = SCAN_SUSPEND;
709 	} else if (associated && bad_latency) {
710 		next_scan_state = SCAN_SUSPEND;
711 	} else {
712 		next_scan_state = SCAN_SET_CHANNEL;
713 	}
714 
715 	local->next_scan_state = next_scan_state;
716 
717 	*next_delay = 0;
718 }
719 
720 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
721 					     unsigned long *next_delay)
722 {
723 	int skip;
724 	struct ieee80211_channel *chan;
725 	enum nl80211_bss_scan_width oper_scan_width;
726 	struct cfg80211_scan_request *scan_req;
727 
728 	scan_req = rcu_dereference_protected(local->scan_req,
729 					     lockdep_is_held(&local->mtx));
730 
731 	skip = 0;
732 	chan = scan_req->channels[local->scan_channel_idx];
733 
734 	local->scan_chandef.chan = chan;
735 	local->scan_chandef.center_freq1 = chan->center_freq;
736 	local->scan_chandef.center_freq2 = 0;
737 	switch (scan_req->scan_width) {
738 	case NL80211_BSS_CHAN_WIDTH_5:
739 		local->scan_chandef.width = NL80211_CHAN_WIDTH_5;
740 		break;
741 	case NL80211_BSS_CHAN_WIDTH_10:
742 		local->scan_chandef.width = NL80211_CHAN_WIDTH_10;
743 		break;
744 	case NL80211_BSS_CHAN_WIDTH_20:
745 		/* If scanning on oper channel, use whatever channel-type
746 		 * is currently in use.
747 		 */
748 		oper_scan_width = cfg80211_chandef_to_scan_width(
749 					&local->_oper_chandef);
750 		if (chan == local->_oper_chandef.chan &&
751 		    oper_scan_width == scan_req->scan_width)
752 			local->scan_chandef = local->_oper_chandef;
753 		else
754 			local->scan_chandef.width = NL80211_CHAN_WIDTH_20_NOHT;
755 		break;
756 	}
757 
758 	if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
759 		skip = 1;
760 
761 	/* advance state machine to next channel/band */
762 	local->scan_channel_idx++;
763 
764 	if (skip) {
765 		/* if we skip this channel return to the decision state */
766 		local->next_scan_state = SCAN_DECISION;
767 		return;
768 	}
769 
770 	/*
771 	 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
772 	 * (which unfortunately doesn't say _why_ step a) is done,
773 	 * but it waits for the probe delay or until a frame is
774 	 * received - and the received frame would update the NAV).
775 	 * For now, we do not support waiting until a frame is
776 	 * received.
777 	 *
778 	 * In any case, it is not necessary for a passive scan.
779 	 */
780 	if ((chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR)) ||
781 	    !scan_req->n_ssids) {
782 		*next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
783 		local->next_scan_state = SCAN_DECISION;
784 		return;
785 	}
786 
787 	/* active scan, send probes */
788 	*next_delay = IEEE80211_PROBE_DELAY;
789 	local->next_scan_state = SCAN_SEND_PROBE;
790 }
791 
792 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
793 					 unsigned long *next_delay)
794 {
795 	/* switch back to the operating channel */
796 	local->scan_chandef.chan = NULL;
797 	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
798 
799 	/* disable PS */
800 	ieee80211_offchannel_return(local);
801 
802 	*next_delay = HZ / 5;
803 	/* afterwards, resume scan & go to next channel */
804 	local->next_scan_state = SCAN_RESUME;
805 }
806 
807 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
808 					unsigned long *next_delay)
809 {
810 	ieee80211_offchannel_stop_vifs(local);
811 
812 	if (local->ops->flush) {
813 		ieee80211_flush_queues(local, NULL, false);
814 		*next_delay = 0;
815 	} else
816 		*next_delay = HZ / 10;
817 
818 	/* remember when we left the operating channel */
819 	local->leave_oper_channel_time = jiffies;
820 
821 	/* advance to the next channel to be scanned */
822 	local->next_scan_state = SCAN_SET_CHANNEL;
823 }
824 
825 void ieee80211_scan_work(struct work_struct *work)
826 {
827 	struct ieee80211_local *local =
828 		container_of(work, struct ieee80211_local, scan_work.work);
829 	struct ieee80211_sub_if_data *sdata;
830 	struct cfg80211_scan_request *scan_req;
831 	unsigned long next_delay = 0;
832 	bool aborted;
833 
834 	mutex_lock(&local->mtx);
835 
836 	if (!ieee80211_can_run_worker(local)) {
837 		aborted = true;
838 		goto out_complete;
839 	}
840 
841 	sdata = rcu_dereference_protected(local->scan_sdata,
842 					  lockdep_is_held(&local->mtx));
843 	scan_req = rcu_dereference_protected(local->scan_req,
844 					     lockdep_is_held(&local->mtx));
845 
846 	/* When scanning on-channel, the first-callback means completed. */
847 	if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
848 		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
849 		goto out_complete;
850 	}
851 
852 	if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
853 		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
854 		goto out_complete;
855 	}
856 
857 	if (!sdata || !scan_req)
858 		goto out;
859 
860 	if (!local->scanning) {
861 		int rc;
862 
863 		RCU_INIT_POINTER(local->scan_req, NULL);
864 		RCU_INIT_POINTER(local->scan_sdata, NULL);
865 
866 		rc = __ieee80211_start_scan(sdata, scan_req);
867 		if (rc) {
868 			/* need to complete scan in cfg80211 */
869 			rcu_assign_pointer(local->scan_req, scan_req);
870 			aborted = true;
871 			goto out_complete;
872 		} else
873 			goto out;
874 	}
875 
876 	/*
877 	 * as long as no delay is required advance immediately
878 	 * without scheduling a new work
879 	 */
880 	do {
881 		if (!ieee80211_sdata_running(sdata)) {
882 			aborted = true;
883 			goto out_complete;
884 		}
885 
886 		switch (local->next_scan_state) {
887 		case SCAN_DECISION:
888 			/* if no more bands/channels left, complete scan */
889 			if (local->scan_channel_idx >= scan_req->n_channels) {
890 				aborted = false;
891 				goto out_complete;
892 			}
893 			ieee80211_scan_state_decision(local, &next_delay);
894 			break;
895 		case SCAN_SET_CHANNEL:
896 			ieee80211_scan_state_set_channel(local, &next_delay);
897 			break;
898 		case SCAN_SEND_PROBE:
899 			ieee80211_scan_state_send_probe(local, &next_delay);
900 			break;
901 		case SCAN_SUSPEND:
902 			ieee80211_scan_state_suspend(local, &next_delay);
903 			break;
904 		case SCAN_RESUME:
905 			ieee80211_scan_state_resume(local, &next_delay);
906 			break;
907 		case SCAN_ABORT:
908 			aborted = true;
909 			goto out_complete;
910 		}
911 	} while (next_delay == 0);
912 
913 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
914 	goto out;
915 
916 out_complete:
917 	__ieee80211_scan_completed(&local->hw, aborted);
918 out:
919 	mutex_unlock(&local->mtx);
920 }
921 
922 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
923 			   struct cfg80211_scan_request *req)
924 {
925 	int res;
926 
927 	mutex_lock(&sdata->local->mtx);
928 	res = __ieee80211_start_scan(sdata, req);
929 	mutex_unlock(&sdata->local->mtx);
930 
931 	return res;
932 }
933 
934 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
935 				const u8 *ssid, u8 ssid_len,
936 				struct ieee80211_channel **channels,
937 				unsigned int n_channels,
938 				enum nl80211_bss_scan_width scan_width)
939 {
940 	struct ieee80211_local *local = sdata->local;
941 	int ret = -EBUSY, i, n_ch = 0;
942 	enum ieee80211_band band;
943 
944 	mutex_lock(&local->mtx);
945 
946 	/* busy scanning */
947 	if (local->scan_req)
948 		goto unlock;
949 
950 	/* fill internal scan request */
951 	if (!channels) {
952 		int max_n;
953 
954 		for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
955 			if (!local->hw.wiphy->bands[band])
956 				continue;
957 
958 			max_n = local->hw.wiphy->bands[band]->n_channels;
959 			for (i = 0; i < max_n; i++) {
960 				struct ieee80211_channel *tmp_ch =
961 				    &local->hw.wiphy->bands[band]->channels[i];
962 
963 				if (tmp_ch->flags & (IEEE80211_CHAN_NO_IR |
964 						     IEEE80211_CHAN_DISABLED))
965 					continue;
966 
967 				local->int_scan_req->channels[n_ch] = tmp_ch;
968 				n_ch++;
969 			}
970 		}
971 
972 		if (WARN_ON_ONCE(n_ch == 0))
973 			goto unlock;
974 
975 		local->int_scan_req->n_channels = n_ch;
976 	} else {
977 		for (i = 0; i < n_channels; i++) {
978 			if (channels[i]->flags & (IEEE80211_CHAN_NO_IR |
979 						  IEEE80211_CHAN_DISABLED))
980 				continue;
981 
982 			local->int_scan_req->channels[n_ch] = channels[i];
983 			n_ch++;
984 		}
985 
986 		if (WARN_ON_ONCE(n_ch == 0))
987 			goto unlock;
988 
989 		local->int_scan_req->n_channels = n_ch;
990 	}
991 
992 	local->int_scan_req->ssids = &local->scan_ssid;
993 	local->int_scan_req->n_ssids = 1;
994 	local->int_scan_req->scan_width = scan_width;
995 	memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
996 	local->int_scan_req->ssids[0].ssid_len = ssid_len;
997 
998 	ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
999  unlock:
1000 	mutex_unlock(&local->mtx);
1001 	return ret;
1002 }
1003 
1004 /*
1005  * Only call this function when a scan can't be queued -- under RTNL.
1006  */
1007 void ieee80211_scan_cancel(struct ieee80211_local *local)
1008 {
1009 	/*
1010 	 * We are canceling software scan, or deferred scan that was not
1011 	 * yet really started (see __ieee80211_start_scan ).
1012 	 *
1013 	 * Regarding hardware scan:
1014 	 * - we can not call  __ieee80211_scan_completed() as when
1015 	 *   SCAN_HW_SCANNING bit is set this function change
1016 	 *   local->hw_scan_req to operate on 5G band, what race with
1017 	 *   driver which can use local->hw_scan_req
1018 	 *
1019 	 * - we can not cancel scan_work since driver can schedule it
1020 	 *   by ieee80211_scan_completed(..., true) to finish scan
1021 	 *
1022 	 * Hence we only call the cancel_hw_scan() callback, but the low-level
1023 	 * driver is still responsible for calling ieee80211_scan_completed()
1024 	 * after the scan was completed/aborted.
1025 	 */
1026 
1027 	mutex_lock(&local->mtx);
1028 	if (!local->scan_req)
1029 		goto out;
1030 
1031 	/*
1032 	 * We have a scan running and the driver already reported completion,
1033 	 * but the worker hasn't run yet or is stuck on the mutex - mark it as
1034 	 * cancelled.
1035 	 */
1036 	if (test_bit(SCAN_HW_SCANNING, &local->scanning) &&
1037 	    test_bit(SCAN_COMPLETED, &local->scanning)) {
1038 		set_bit(SCAN_HW_CANCELLED, &local->scanning);
1039 		goto out;
1040 	}
1041 
1042 	if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
1043 		/*
1044 		 * Make sure that __ieee80211_scan_completed doesn't trigger a
1045 		 * scan on another band.
1046 		 */
1047 		set_bit(SCAN_HW_CANCELLED, &local->scanning);
1048 		if (local->ops->cancel_hw_scan)
1049 			drv_cancel_hw_scan(local,
1050 				rcu_dereference_protected(local->scan_sdata,
1051 						lockdep_is_held(&local->mtx)));
1052 		goto out;
1053 	}
1054 
1055 	/*
1056 	 * If the work is currently running, it must be blocked on
1057 	 * the mutex, but we'll set scan_sdata = NULL and it'll
1058 	 * simply exit once it acquires the mutex.
1059 	 */
1060 	cancel_delayed_work(&local->scan_work);
1061 	/* and clean up */
1062 	__ieee80211_scan_completed(&local->hw, true);
1063 out:
1064 	mutex_unlock(&local->mtx);
1065 }
1066 
1067 int __ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
1068 					struct cfg80211_sched_scan_request *req)
1069 {
1070 	struct ieee80211_local *local = sdata->local;
1071 	struct ieee80211_scan_ies sched_scan_ies = {};
1072 	struct cfg80211_chan_def chandef;
1073 	int ret, i, iebufsz, num_bands = 0;
1074 	u32 rate_masks[IEEE80211_NUM_BANDS] = {};
1075 	u8 bands_used = 0;
1076 	u8 *ie;
1077 	size_t len;
1078 
1079 	iebufsz = local->scan_ies_len + req->ie_len;
1080 
1081 	lockdep_assert_held(&local->mtx);
1082 
1083 	if (!local->ops->sched_scan_start)
1084 		return -ENOTSUPP;
1085 
1086 	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
1087 		if (local->hw.wiphy->bands[i]) {
1088 			bands_used |= BIT(i);
1089 			rate_masks[i] = (u32) -1;
1090 			num_bands++;
1091 		}
1092 	}
1093 
1094 	ie = kzalloc(num_bands * iebufsz, GFP_KERNEL);
1095 	if (!ie) {
1096 		ret = -ENOMEM;
1097 		goto out;
1098 	}
1099 
1100 	ieee80211_prepare_scan_chandef(&chandef, req->scan_width);
1101 
1102 	len = ieee80211_build_preq_ies(local, ie, num_bands * iebufsz,
1103 				       &sched_scan_ies, req->ie,
1104 				       req->ie_len, bands_used,
1105 				       rate_masks, &chandef);
1106 
1107 	ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);
1108 	if (ret == 0) {
1109 		rcu_assign_pointer(local->sched_scan_sdata, sdata);
1110 		rcu_assign_pointer(local->sched_scan_req, req);
1111 	}
1112 
1113 	kfree(ie);
1114 
1115 out:
1116 	if (ret) {
1117 		/* Clean in case of failure after HW restart or upon resume. */
1118 		RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1119 		RCU_INIT_POINTER(local->sched_scan_req, NULL);
1120 	}
1121 
1122 	return ret;
1123 }
1124 
1125 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
1126 				       struct cfg80211_sched_scan_request *req)
1127 {
1128 	struct ieee80211_local *local = sdata->local;
1129 	int ret;
1130 
1131 	mutex_lock(&local->mtx);
1132 
1133 	if (rcu_access_pointer(local->sched_scan_sdata)) {
1134 		mutex_unlock(&local->mtx);
1135 		return -EBUSY;
1136 	}
1137 
1138 	ret = __ieee80211_request_sched_scan_start(sdata, req);
1139 
1140 	mutex_unlock(&local->mtx);
1141 	return ret;
1142 }
1143 
1144 int ieee80211_request_sched_scan_stop(struct ieee80211_local *local)
1145 {
1146 	struct ieee80211_sub_if_data *sched_scan_sdata;
1147 	int ret = -ENOENT;
1148 
1149 	mutex_lock(&local->mtx);
1150 
1151 	if (!local->ops->sched_scan_stop) {
1152 		ret = -ENOTSUPP;
1153 		goto out;
1154 	}
1155 
1156 	/* We don't want to restart sched scan anymore. */
1157 	RCU_INIT_POINTER(local->sched_scan_req, NULL);
1158 
1159 	sched_scan_sdata = rcu_dereference_protected(local->sched_scan_sdata,
1160 						lockdep_is_held(&local->mtx));
1161 	if (sched_scan_sdata) {
1162 		ret = drv_sched_scan_stop(local, sched_scan_sdata);
1163 		if (!ret)
1164 			RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1165 	}
1166 out:
1167 	mutex_unlock(&local->mtx);
1168 
1169 	return ret;
1170 }
1171 
1172 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
1173 {
1174 	struct ieee80211_local *local = hw_to_local(hw);
1175 
1176 	trace_api_sched_scan_results(local);
1177 
1178 	cfg80211_sched_scan_results(hw->wiphy);
1179 }
1180 EXPORT_SYMBOL(ieee80211_sched_scan_results);
1181 
1182 void ieee80211_sched_scan_end(struct ieee80211_local *local)
1183 {
1184 	mutex_lock(&local->mtx);
1185 
1186 	if (!rcu_access_pointer(local->sched_scan_sdata)) {
1187 		mutex_unlock(&local->mtx);
1188 		return;
1189 	}
1190 
1191 	RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1192 
1193 	/* If sched scan was aborted by the driver. */
1194 	RCU_INIT_POINTER(local->sched_scan_req, NULL);
1195 
1196 	mutex_unlock(&local->mtx);
1197 
1198 	cfg80211_sched_scan_stopped(local->hw.wiphy);
1199 }
1200 
1201 void ieee80211_sched_scan_stopped_work(struct work_struct *work)
1202 {
1203 	struct ieee80211_local *local =
1204 		container_of(work, struct ieee80211_local,
1205 			     sched_scan_stopped_work);
1206 
1207 	ieee80211_sched_scan_end(local);
1208 }
1209 
1210 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
1211 {
1212 	struct ieee80211_local *local = hw_to_local(hw);
1213 
1214 	trace_api_sched_scan_stopped(local);
1215 
1216 	schedule_work(&local->sched_scan_stopped_work);
1217 }
1218 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);
1219