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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 2013-2014  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 <linux/pm_qos.h>
20 #include <net/sch_generic.h>
21 #include <linux/slab.h>
22 #include <linux/export.h>
23 #include <net/mac80211.h>
24 
25 #include "ieee80211_i.h"
26 #include "driver-ops.h"
27 #include "mesh.h"
28 
29 #define IEEE80211_PROBE_DELAY (HZ / 33)
30 #define IEEE80211_CHANNEL_TIME (HZ / 33)
31 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 9)
32 
ieee80211_rx_bss_put(struct ieee80211_local * local,struct ieee80211_bss * bss)33 void ieee80211_rx_bss_put(struct ieee80211_local *local,
34 			  struct ieee80211_bss *bss)
35 {
36 	if (!bss)
37 		return;
38 	cfg80211_put_bss(local->hw.wiphy,
39 			 container_of((void *)bss, struct cfg80211_bss, priv));
40 }
41 
is_uapsd_supported(struct ieee802_11_elems * elems)42 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
43 {
44 	u8 qos_info;
45 
46 	if (elems->wmm_info && elems->wmm_info_len == 7
47 	    && elems->wmm_info[5] == 1)
48 		qos_info = elems->wmm_info[6];
49 	else if (elems->wmm_param && elems->wmm_param_len == 24
50 		 && elems->wmm_param[5] == 1)
51 		qos_info = elems->wmm_param[6];
52 	else
53 		/* no valid wmm information or parameter element found */
54 		return false;
55 
56 	return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
57 }
58 
59 struct ieee80211_bss *
ieee80211_bss_info_update(struct ieee80211_local * local,struct ieee80211_rx_status * rx_status,struct ieee80211_mgmt * mgmt,size_t len,struct ieee802_11_elems * elems,struct ieee80211_channel * channel)60 ieee80211_bss_info_update(struct ieee80211_local *local,
61 			  struct ieee80211_rx_status *rx_status,
62 			  struct ieee80211_mgmt *mgmt, size_t len,
63 			  struct ieee802_11_elems *elems,
64 			  struct ieee80211_channel *channel)
65 {
66 	bool beacon = ieee80211_is_beacon(mgmt->frame_control);
67 	struct cfg80211_bss *cbss;
68 	struct ieee80211_bss *bss;
69 	int clen, srlen;
70 	enum nl80211_bss_scan_width scan_width;
71 	s32 signal = 0;
72 
73 	if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
74 		signal = rx_status->signal * 100;
75 	else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
76 		signal = (rx_status->signal * 100) / local->hw.max_signal;
77 
78 	scan_width = NL80211_BSS_CHAN_WIDTH_20;
79 	if (rx_status->flag & RX_FLAG_5MHZ)
80 		scan_width = NL80211_BSS_CHAN_WIDTH_5;
81 	if (rx_status->flag & RX_FLAG_10MHZ)
82 		scan_width = NL80211_BSS_CHAN_WIDTH_10;
83 
84 	cbss = cfg80211_inform_bss_width_frame(local->hw.wiphy, channel,
85 					       scan_width, mgmt, len, signal,
86 					       GFP_ATOMIC);
87 	if (!cbss)
88 		return NULL;
89 
90 	bss = (void *)cbss->priv;
91 
92 	if (beacon)
93 		bss->device_ts_beacon = rx_status->device_timestamp;
94 	else
95 		bss->device_ts_presp = rx_status->device_timestamp;
96 
97 	if (elems->parse_error) {
98 		if (beacon)
99 			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_BEACON;
100 		else
101 			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_PROBE_RESP;
102 	} else {
103 		if (beacon)
104 			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_BEACON;
105 		else
106 			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_PROBE_RESP;
107 	}
108 
109 	/* save the ERP value so that it is available at association time */
110 	if (elems->erp_info && (!elems->parse_error ||
111 				!(bss->valid_data & IEEE80211_BSS_VALID_ERP))) {
112 		bss->erp_value = elems->erp_info[0];
113 		bss->has_erp_value = true;
114 		if (!elems->parse_error)
115 			bss->valid_data |= IEEE80211_BSS_VALID_ERP;
116 	}
117 
118 	/* replace old supported rates if we get new values */
119 	if (!elems->parse_error ||
120 	    !(bss->valid_data & IEEE80211_BSS_VALID_RATES)) {
121 		srlen = 0;
122 		if (elems->supp_rates) {
123 			clen = IEEE80211_MAX_SUPP_RATES;
124 			if (clen > elems->supp_rates_len)
125 				clen = elems->supp_rates_len;
126 			memcpy(bss->supp_rates, elems->supp_rates, clen);
127 			srlen += clen;
128 		}
129 		if (elems->ext_supp_rates) {
130 			clen = IEEE80211_MAX_SUPP_RATES - srlen;
131 			if (clen > elems->ext_supp_rates_len)
132 				clen = elems->ext_supp_rates_len;
133 			memcpy(bss->supp_rates + srlen, elems->ext_supp_rates,
134 			       clen);
135 			srlen += clen;
136 		}
137 		if (srlen) {
138 			bss->supp_rates_len = srlen;
139 			if (!elems->parse_error)
140 				bss->valid_data |= IEEE80211_BSS_VALID_RATES;
141 		}
142 	}
143 
144 	if (!elems->parse_error ||
145 	    !(bss->valid_data & IEEE80211_BSS_VALID_WMM)) {
146 		bss->wmm_used = elems->wmm_param || elems->wmm_info;
147 		bss->uapsd_supported = is_uapsd_supported(elems);
148 		if (!elems->parse_error)
149 			bss->valid_data |= IEEE80211_BSS_VALID_WMM;
150 	}
151 
152 	if (beacon) {
153 		struct ieee80211_supported_band *sband =
154 			local->hw.wiphy->bands[rx_status->band];
155 		if (!(rx_status->flag & RX_FLAG_HT) &&
156 		    !(rx_status->flag & RX_FLAG_VHT))
157 			bss->beacon_rate =
158 				&sband->bitrates[rx_status->rate_idx];
159 	}
160 
161 	return bss;
162 }
163 
ieee80211_scan_rx(struct ieee80211_local * local,struct sk_buff * skb)164 void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
165 {
166 	struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
167 	struct ieee80211_sub_if_data *sdata1, *sdata2;
168 	struct ieee80211_mgmt *mgmt = (void *)skb->data;
169 	struct ieee80211_bss *bss;
170 	u8 *elements;
171 	struct ieee80211_channel *channel;
172 	size_t baselen;
173 	struct ieee802_11_elems elems;
174 
175 	if (skb->len < 24 ||
176 	    (!ieee80211_is_probe_resp(mgmt->frame_control) &&
177 	     !ieee80211_is_beacon(mgmt->frame_control)))
178 		return;
179 
180 	sdata1 = rcu_dereference(local->scan_sdata);
181 	sdata2 = rcu_dereference(local->sched_scan_sdata);
182 
183 	if (likely(!sdata1 && !sdata2))
184 		return;
185 
186 	if (ieee80211_is_probe_resp(mgmt->frame_control)) {
187 		/* ignore ProbeResp to foreign address */
188 		if ((!sdata1 || !ether_addr_equal(mgmt->da, sdata1->vif.addr)) &&
189 		    (!sdata2 || !ether_addr_equal(mgmt->da, sdata2->vif.addr)))
190 			return;
191 
192 		elements = mgmt->u.probe_resp.variable;
193 		baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
194 	} else {
195 		baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
196 		elements = mgmt->u.beacon.variable;
197 	}
198 
199 	if (baselen > skb->len)
200 		return;
201 
202 	ieee802_11_parse_elems(elements, skb->len - baselen, false, &elems);
203 
204 	channel = ieee80211_get_channel(local->hw.wiphy, rx_status->freq);
205 
206 	if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
207 		return;
208 
209 	bss = ieee80211_bss_info_update(local, rx_status,
210 					mgmt, skb->len, &elems,
211 					channel);
212 	if (bss)
213 		ieee80211_rx_bss_put(local, bss);
214 }
215 
216 static void
ieee80211_prepare_scan_chandef(struct cfg80211_chan_def * chandef,enum nl80211_bss_scan_width scan_width)217 ieee80211_prepare_scan_chandef(struct cfg80211_chan_def *chandef,
218 			       enum nl80211_bss_scan_width scan_width)
219 {
220 	memset(chandef, 0, sizeof(*chandef));
221 	switch (scan_width) {
222 	case NL80211_BSS_CHAN_WIDTH_5:
223 		chandef->width = NL80211_CHAN_WIDTH_5;
224 		break;
225 	case NL80211_BSS_CHAN_WIDTH_10:
226 		chandef->width = NL80211_CHAN_WIDTH_10;
227 		break;
228 	default:
229 		chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
230 		break;
231 	}
232 }
233 
234 /* return false if no more work */
ieee80211_prep_hw_scan(struct ieee80211_local * local)235 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
236 {
237 	struct cfg80211_scan_request *req = local->scan_req;
238 	struct cfg80211_chan_def chandef;
239 	u8 bands_used = 0;
240 	int i, ielen, n_chans;
241 
242 	if (test_bit(SCAN_HW_CANCELLED, &local->scanning))
243 		return false;
244 
245 	if (local->hw.flags & IEEE80211_SINGLE_HW_SCAN_ON_ALL_BANDS) {
246 		for (i = 0; i < req->n_channels; i++) {
247 			local->hw_scan_req->req.channels[i] = req->channels[i];
248 			bands_used |= BIT(req->channels[i]->band);
249 		}
250 
251 		n_chans = req->n_channels;
252 	} else {
253 		do {
254 			if (local->hw_scan_band == IEEE80211_NUM_BANDS)
255 				return false;
256 
257 			n_chans = 0;
258 
259 			for (i = 0; i < req->n_channels; i++) {
260 				if (req->channels[i]->band !=
261 				    local->hw_scan_band)
262 					continue;
263 				local->hw_scan_req->req.channels[n_chans] =
264 							req->channels[i];
265 				n_chans++;
266 				bands_used |= BIT(req->channels[i]->band);
267 			}
268 
269 			local->hw_scan_band++;
270 		} while (!n_chans);
271 	}
272 
273 	local->hw_scan_req->req.n_channels = n_chans;
274 	ieee80211_prepare_scan_chandef(&chandef, req->scan_width);
275 
276 	ielen = ieee80211_build_preq_ies(local,
277 					 (u8 *)local->hw_scan_req->req.ie,
278 					 local->hw_scan_ies_bufsize,
279 					 &local->hw_scan_req->ies,
280 					 req->ie, req->ie_len,
281 					 bands_used, req->rates, &chandef);
282 	local->hw_scan_req->req.ie_len = ielen;
283 	local->hw_scan_req->req.no_cck = req->no_cck;
284 
285 	return true;
286 }
287 
__ieee80211_scan_completed(struct ieee80211_hw * hw,bool aborted)288 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
289 {
290 	struct ieee80211_local *local = hw_to_local(hw);
291 	bool hw_scan = local->ops->hw_scan;
292 	bool was_scanning = local->scanning;
293 	struct ieee80211_sub_if_data *sdata;
294 
295 	lockdep_assert_held(&local->mtx);
296 
297 	/*
298 	 * It's ok to abort a not-yet-running scan (that
299 	 * we have one at all will be verified by checking
300 	 * local->scan_req next), but not to complete it
301 	 * successfully.
302 	 */
303 	if (WARN_ON(!local->scanning && !aborted))
304 		aborted = true;
305 
306 	if (WARN_ON(!local->scan_req))
307 		return;
308 
309 	if (hw_scan && !aborted &&
310 	    !(local->hw.flags & IEEE80211_SINGLE_HW_SCAN_ON_ALL_BANDS) &&
311 	    ieee80211_prep_hw_scan(local)) {
312 		int rc;
313 
314 		rc = drv_hw_scan(local,
315 			rcu_dereference_protected(local->scan_sdata,
316 						  lockdep_is_held(&local->mtx)),
317 			local->hw_scan_req);
318 
319 		if (rc == 0)
320 			return;
321 	}
322 
323 	kfree(local->hw_scan_req);
324 	local->hw_scan_req = NULL;
325 
326 	if (local->scan_req != local->int_scan_req)
327 		cfg80211_scan_done(local->scan_req, aborted);
328 	local->scan_req = NULL;
329 	RCU_INIT_POINTER(local->scan_sdata, NULL);
330 
331 	local->scanning = 0;
332 	local->scan_chandef.chan = NULL;
333 
334 	/* Set power back to normal operating levels. */
335 	ieee80211_hw_config(local, 0);
336 
337 	if (!hw_scan) {
338 		ieee80211_configure_filter(local);
339 		drv_sw_scan_complete(local);
340 		ieee80211_offchannel_return(local);
341 	}
342 
343 	ieee80211_recalc_idle(local);
344 
345 	ieee80211_mlme_notify_scan_completed(local);
346 	ieee80211_ibss_notify_scan_completed(local);
347 
348 	/* Requeue all the work that might have been ignored while
349 	 * the scan was in progress; if there was none this will
350 	 * just be a no-op for the particular interface.
351 	 */
352 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
353 		if (ieee80211_sdata_running(sdata))
354 			ieee80211_queue_work(&sdata->local->hw, &sdata->work);
355 	}
356 
357 	if (was_scanning)
358 		ieee80211_start_next_roc(local);
359 }
360 
ieee80211_scan_completed(struct ieee80211_hw * hw,bool aborted)361 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
362 {
363 	struct ieee80211_local *local = hw_to_local(hw);
364 
365 	trace_api_scan_completed(local, aborted);
366 
367 	set_bit(SCAN_COMPLETED, &local->scanning);
368 	if (aborted)
369 		set_bit(SCAN_ABORTED, &local->scanning);
370 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
371 }
372 EXPORT_SYMBOL(ieee80211_scan_completed);
373 
ieee80211_start_sw_scan(struct ieee80211_local * local)374 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
375 {
376 	/* Software scan is not supported in multi-channel cases */
377 	if (local->use_chanctx)
378 		return -EOPNOTSUPP;
379 
380 	/*
381 	 * Hardware/driver doesn't support hw_scan, so use software
382 	 * scanning instead. First send a nullfunc frame with power save
383 	 * bit on so that AP will buffer the frames for us while we are not
384 	 * listening, then send probe requests to each channel and wait for
385 	 * the responses. After all channels are scanned, tune back to the
386 	 * original channel and send a nullfunc frame with power save bit
387 	 * off to trigger the AP to send us all the buffered frames.
388 	 *
389 	 * Note that while local->sw_scanning is true everything else but
390 	 * nullfunc frames and probe requests will be dropped in
391 	 * ieee80211_tx_h_check_assoc().
392 	 */
393 	drv_sw_scan_start(local);
394 
395 	local->leave_oper_channel_time = jiffies;
396 	local->next_scan_state = SCAN_DECISION;
397 	local->scan_channel_idx = 0;
398 
399 	ieee80211_offchannel_stop_vifs(local);
400 
401 	/* ensure nullfunc is transmitted before leaving operating channel */
402 	ieee80211_flush_queues(local, NULL);
403 
404 	ieee80211_configure_filter(local);
405 
406 	/* We need to set power level at maximum rate for scanning. */
407 	ieee80211_hw_config(local, 0);
408 
409 	ieee80211_queue_delayed_work(&local->hw,
410 				     &local->scan_work, 0);
411 
412 	return 0;
413 }
414 
ieee80211_can_scan(struct ieee80211_local * local,struct ieee80211_sub_if_data * sdata)415 static bool ieee80211_can_scan(struct ieee80211_local *local,
416 			       struct ieee80211_sub_if_data *sdata)
417 {
418 	if (local->radar_detect_enabled)
419 		return false;
420 
421 	if (!list_empty(&local->roc_list))
422 		return false;
423 
424 	if (sdata->vif.type == NL80211_IFTYPE_STATION &&
425 	    sdata->u.mgd.flags & IEEE80211_STA_CONNECTION_POLL)
426 		return false;
427 
428 	return true;
429 }
430 
ieee80211_run_deferred_scan(struct ieee80211_local * local)431 void ieee80211_run_deferred_scan(struct ieee80211_local *local)
432 {
433 	lockdep_assert_held(&local->mtx);
434 
435 	if (!local->scan_req || local->scanning)
436 		return;
437 
438 	if (!ieee80211_can_scan(local,
439 				rcu_dereference_protected(
440 					local->scan_sdata,
441 					lockdep_is_held(&local->mtx))))
442 		return;
443 
444 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
445 				     round_jiffies_relative(0));
446 }
447 
ieee80211_scan_state_send_probe(struct ieee80211_local * local,unsigned long * next_delay)448 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
449 					    unsigned long *next_delay)
450 {
451 	int i;
452 	struct ieee80211_sub_if_data *sdata;
453 	enum ieee80211_band band = local->hw.conf.chandef.chan->band;
454 	u32 tx_flags;
455 
456 	tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
457 	if (local->scan_req->no_cck)
458 		tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;
459 
460 	sdata = rcu_dereference_protected(local->scan_sdata,
461 					  lockdep_is_held(&local->mtx));
462 
463 	for (i = 0; i < local->scan_req->n_ssids; i++)
464 		ieee80211_send_probe_req(
465 			sdata, NULL,
466 			local->scan_req->ssids[i].ssid,
467 			local->scan_req->ssids[i].ssid_len,
468 			local->scan_req->ie, local->scan_req->ie_len,
469 			local->scan_req->rates[band], false,
470 			tx_flags, local->hw.conf.chandef.chan, true);
471 
472 	/*
473 	 * After sending probe requests, wait for probe responses
474 	 * on the channel.
475 	 */
476 	*next_delay = IEEE80211_CHANNEL_TIME;
477 	local->next_scan_state = SCAN_DECISION;
478 }
479 
__ieee80211_start_scan(struct ieee80211_sub_if_data * sdata,struct cfg80211_scan_request * req)480 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
481 				  struct cfg80211_scan_request *req)
482 {
483 	struct ieee80211_local *local = sdata->local;
484 	int rc;
485 
486 	lockdep_assert_held(&local->mtx);
487 
488 	if (local->scan_req)
489 		return -EBUSY;
490 
491 	if (!ieee80211_can_scan(local, sdata)) {
492 		/* wait for the work to finish/time out */
493 		local->scan_req = req;
494 		rcu_assign_pointer(local->scan_sdata, sdata);
495 		return 0;
496 	}
497 
498 	if (local->ops->hw_scan) {
499 		u8 *ies;
500 
501 		local->hw_scan_ies_bufsize = local->scan_ies_len + req->ie_len;
502 
503 		if (local->hw.flags & IEEE80211_SINGLE_HW_SCAN_ON_ALL_BANDS) {
504 			int i, n_bands = 0;
505 			u8 bands_counted = 0;
506 
507 			for (i = 0; i < req->n_channels; i++) {
508 				if (bands_counted & BIT(req->channels[i]->band))
509 					continue;
510 				bands_counted |= BIT(req->channels[i]->band);
511 				n_bands++;
512 			}
513 
514 			local->hw_scan_ies_bufsize *= n_bands;
515 		}
516 
517 		local->hw_scan_req = kmalloc(
518 				sizeof(*local->hw_scan_req) +
519 				req->n_channels * sizeof(req->channels[0]) +
520 				local->hw_scan_ies_bufsize, GFP_KERNEL);
521 		if (!local->hw_scan_req)
522 			return -ENOMEM;
523 
524 		local->hw_scan_req->req.ssids = req->ssids;
525 		local->hw_scan_req->req.n_ssids = req->n_ssids;
526 		ies = (u8 *)local->hw_scan_req +
527 			sizeof(*local->hw_scan_req) +
528 			req->n_channels * sizeof(req->channels[0]);
529 		local->hw_scan_req->req.ie = ies;
530 		local->hw_scan_req->req.flags = req->flags;
531 
532 		local->hw_scan_band = 0;
533 
534 		/*
535 		 * After allocating local->hw_scan_req, we must
536 		 * go through until ieee80211_prep_hw_scan(), so
537 		 * anything that might be changed here and leave
538 		 * this function early must not go after this
539 		 * allocation.
540 		 */
541 	}
542 
543 	local->scan_req = req;
544 	rcu_assign_pointer(local->scan_sdata, sdata);
545 
546 	if (local->ops->hw_scan) {
547 		__set_bit(SCAN_HW_SCANNING, &local->scanning);
548 	} else if ((req->n_channels == 1) &&
549 		   (req->channels[0] == local->_oper_chandef.chan)) {
550 		/*
551 		 * If we are scanning only on the operating channel
552 		 * then we do not need to stop normal activities
553 		 */
554 		unsigned long next_delay;
555 
556 		__set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
557 
558 		ieee80211_recalc_idle(local);
559 
560 		/* Notify driver scan is starting, keep order of operations
561 		 * same as normal software scan, in case that matters. */
562 		drv_sw_scan_start(local);
563 
564 		ieee80211_configure_filter(local); /* accept probe-responses */
565 
566 		/* We need to ensure power level is at max for scanning. */
567 		ieee80211_hw_config(local, 0);
568 
569 		if ((req->channels[0]->flags &
570 		     IEEE80211_CHAN_NO_IR) ||
571 		    !local->scan_req->n_ssids) {
572 			next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
573 		} else {
574 			ieee80211_scan_state_send_probe(local, &next_delay);
575 			next_delay = IEEE80211_CHANNEL_TIME;
576 		}
577 
578 		/* Now, just wait a bit and we are all done! */
579 		ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
580 					     next_delay);
581 		return 0;
582 	} else {
583 		/* Do normal software scan */
584 		__set_bit(SCAN_SW_SCANNING, &local->scanning);
585 	}
586 
587 	ieee80211_recalc_idle(local);
588 
589 	if (local->ops->hw_scan) {
590 		WARN_ON(!ieee80211_prep_hw_scan(local));
591 		rc = drv_hw_scan(local, sdata, local->hw_scan_req);
592 	} else
593 		rc = ieee80211_start_sw_scan(local);
594 
595 	if (rc) {
596 		kfree(local->hw_scan_req);
597 		local->hw_scan_req = NULL;
598 		local->scanning = 0;
599 
600 		ieee80211_recalc_idle(local);
601 
602 		local->scan_req = NULL;
603 		RCU_INIT_POINTER(local->scan_sdata, NULL);
604 	}
605 
606 	return rc;
607 }
608 
609 static unsigned long
ieee80211_scan_get_channel_time(struct ieee80211_channel * chan)610 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
611 {
612 	/*
613 	 * TODO: channel switching also consumes quite some time,
614 	 * add that delay as well to get a better estimation
615 	 */
616 	if (chan->flags & IEEE80211_CHAN_NO_IR)
617 		return IEEE80211_PASSIVE_CHANNEL_TIME;
618 	return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
619 }
620 
ieee80211_scan_state_decision(struct ieee80211_local * local,unsigned long * next_delay)621 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
622 					  unsigned long *next_delay)
623 {
624 	bool associated = false;
625 	bool tx_empty = true;
626 	bool bad_latency;
627 	struct ieee80211_sub_if_data *sdata;
628 	struct ieee80211_channel *next_chan;
629 	enum mac80211_scan_state next_scan_state;
630 
631 	/*
632 	 * check if at least one STA interface is associated,
633 	 * check if at least one STA interface has pending tx frames
634 	 * and grab the lowest used beacon interval
635 	 */
636 	mutex_lock(&local->iflist_mtx);
637 	list_for_each_entry(sdata, &local->interfaces, list) {
638 		if (!ieee80211_sdata_running(sdata))
639 			continue;
640 
641 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
642 			if (sdata->u.mgd.associated) {
643 				associated = true;
644 
645 				if (!qdisc_all_tx_empty(sdata->dev)) {
646 					tx_empty = false;
647 					break;
648 				}
649 			}
650 		}
651 	}
652 	mutex_unlock(&local->iflist_mtx);
653 
654 	next_chan = local->scan_req->channels[local->scan_channel_idx];
655 
656 	/*
657 	 * we're currently scanning a different channel, let's
658 	 * see if we can scan another channel without interfering
659 	 * with the current traffic situation.
660 	 *
661 	 * Keep good latency, do not stay off-channel more than 125 ms.
662 	 */
663 
664 	bad_latency = time_after(jiffies +
665 				 ieee80211_scan_get_channel_time(next_chan),
666 				 local->leave_oper_channel_time + HZ / 8);
667 
668 	if (associated && !tx_empty) {
669 		if (local->scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
670 			next_scan_state = SCAN_ABORT;
671 		else
672 			next_scan_state = SCAN_SUSPEND;
673 	} else if (associated && bad_latency) {
674 		next_scan_state = SCAN_SUSPEND;
675 	} else {
676 		next_scan_state = SCAN_SET_CHANNEL;
677 	}
678 
679 	local->next_scan_state = next_scan_state;
680 
681 	*next_delay = 0;
682 }
683 
ieee80211_scan_state_set_channel(struct ieee80211_local * local,unsigned long * next_delay)684 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
685 					     unsigned long *next_delay)
686 {
687 	int skip;
688 	struct ieee80211_channel *chan;
689 	enum nl80211_bss_scan_width oper_scan_width;
690 
691 	skip = 0;
692 	chan = local->scan_req->channels[local->scan_channel_idx];
693 
694 	local->scan_chandef.chan = chan;
695 	local->scan_chandef.center_freq1 = chan->center_freq;
696 	local->scan_chandef.center_freq2 = 0;
697 	switch (local->scan_req->scan_width) {
698 	case NL80211_BSS_CHAN_WIDTH_5:
699 		local->scan_chandef.width = NL80211_CHAN_WIDTH_5;
700 		break;
701 	case NL80211_BSS_CHAN_WIDTH_10:
702 		local->scan_chandef.width = NL80211_CHAN_WIDTH_10;
703 		break;
704 	case NL80211_BSS_CHAN_WIDTH_20:
705 		/* If scanning on oper channel, use whatever channel-type
706 		 * is currently in use.
707 		 */
708 		oper_scan_width = cfg80211_chandef_to_scan_width(
709 					&local->_oper_chandef);
710 		if (chan == local->_oper_chandef.chan &&
711 		    oper_scan_width == local->scan_req->scan_width)
712 			local->scan_chandef = local->_oper_chandef;
713 		else
714 			local->scan_chandef.width = NL80211_CHAN_WIDTH_20_NOHT;
715 		break;
716 	}
717 
718 	if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
719 		skip = 1;
720 
721 	/* advance state machine to next channel/band */
722 	local->scan_channel_idx++;
723 
724 	if (skip) {
725 		/* if we skip this channel return to the decision state */
726 		local->next_scan_state = SCAN_DECISION;
727 		return;
728 	}
729 
730 	/*
731 	 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
732 	 * (which unfortunately doesn't say _why_ step a) is done,
733 	 * but it waits for the probe delay or until a frame is
734 	 * received - and the received frame would update the NAV).
735 	 * For now, we do not support waiting until a frame is
736 	 * received.
737 	 *
738 	 * In any case, it is not necessary for a passive scan.
739 	 */
740 	if (chan->flags & IEEE80211_CHAN_NO_IR ||
741 	    !local->scan_req->n_ssids) {
742 		*next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
743 		local->next_scan_state = SCAN_DECISION;
744 		return;
745 	}
746 
747 	/* active scan, send probes */
748 	*next_delay = IEEE80211_PROBE_DELAY;
749 	local->next_scan_state = SCAN_SEND_PROBE;
750 }
751 
ieee80211_scan_state_suspend(struct ieee80211_local * local,unsigned long * next_delay)752 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
753 					 unsigned long *next_delay)
754 {
755 	/* switch back to the operating channel */
756 	local->scan_chandef.chan = NULL;
757 	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
758 
759 	/* disable PS */
760 	ieee80211_offchannel_return(local);
761 
762 	*next_delay = HZ / 5;
763 	/* afterwards, resume scan & go to next channel */
764 	local->next_scan_state = SCAN_RESUME;
765 }
766 
ieee80211_scan_state_resume(struct ieee80211_local * local,unsigned long * next_delay)767 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
768 					unsigned long *next_delay)
769 {
770 	ieee80211_offchannel_stop_vifs(local);
771 
772 	if (local->ops->flush) {
773 		ieee80211_flush_queues(local, NULL);
774 		*next_delay = 0;
775 	} else
776 		*next_delay = HZ / 10;
777 
778 	/* remember when we left the operating channel */
779 	local->leave_oper_channel_time = jiffies;
780 
781 	/* advance to the next channel to be scanned */
782 	local->next_scan_state = SCAN_SET_CHANNEL;
783 }
784 
ieee80211_scan_work(struct work_struct * work)785 void ieee80211_scan_work(struct work_struct *work)
786 {
787 	struct ieee80211_local *local =
788 		container_of(work, struct ieee80211_local, scan_work.work);
789 	struct ieee80211_sub_if_data *sdata;
790 	unsigned long next_delay = 0;
791 	bool aborted;
792 
793 	mutex_lock(&local->mtx);
794 
795 	sdata = rcu_dereference_protected(local->scan_sdata,
796 					  lockdep_is_held(&local->mtx));
797 
798 	/* When scanning on-channel, the first-callback means completed. */
799 	if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
800 		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
801 		goto out_complete;
802 	}
803 
804 	if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
805 		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
806 		goto out_complete;
807 	}
808 
809 	if (!sdata || !local->scan_req)
810 		goto out;
811 
812 	if (local->scan_req && !local->scanning) {
813 		struct cfg80211_scan_request *req = local->scan_req;
814 		int rc;
815 
816 		local->scan_req = NULL;
817 		RCU_INIT_POINTER(local->scan_sdata, NULL);
818 
819 		rc = __ieee80211_start_scan(sdata, req);
820 		if (rc) {
821 			/* need to complete scan in cfg80211 */
822 			local->scan_req = req;
823 			aborted = true;
824 			goto out_complete;
825 		} else
826 			goto out;
827 	}
828 
829 	/*
830 	 * as long as no delay is required advance immediately
831 	 * without scheduling a new work
832 	 */
833 	do {
834 		if (!ieee80211_sdata_running(sdata)) {
835 			aborted = true;
836 			goto out_complete;
837 		}
838 
839 		switch (local->next_scan_state) {
840 		case SCAN_DECISION:
841 			/* if no more bands/channels left, complete scan */
842 			if (local->scan_channel_idx >= local->scan_req->n_channels) {
843 				aborted = false;
844 				goto out_complete;
845 			}
846 			ieee80211_scan_state_decision(local, &next_delay);
847 			break;
848 		case SCAN_SET_CHANNEL:
849 			ieee80211_scan_state_set_channel(local, &next_delay);
850 			break;
851 		case SCAN_SEND_PROBE:
852 			ieee80211_scan_state_send_probe(local, &next_delay);
853 			break;
854 		case SCAN_SUSPEND:
855 			ieee80211_scan_state_suspend(local, &next_delay);
856 			break;
857 		case SCAN_RESUME:
858 			ieee80211_scan_state_resume(local, &next_delay);
859 			break;
860 		case SCAN_ABORT:
861 			aborted = true;
862 			goto out_complete;
863 		}
864 	} while (next_delay == 0);
865 
866 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
867 	goto out;
868 
869 out_complete:
870 	__ieee80211_scan_completed(&local->hw, aborted);
871 out:
872 	mutex_unlock(&local->mtx);
873 }
874 
ieee80211_request_scan(struct ieee80211_sub_if_data * sdata,struct cfg80211_scan_request * req)875 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
876 			   struct cfg80211_scan_request *req)
877 {
878 	int res;
879 
880 	mutex_lock(&sdata->local->mtx);
881 	res = __ieee80211_start_scan(sdata, req);
882 	mutex_unlock(&sdata->local->mtx);
883 
884 	return res;
885 }
886 
ieee80211_request_ibss_scan(struct ieee80211_sub_if_data * sdata,const u8 * ssid,u8 ssid_len,struct ieee80211_channel * chan,enum nl80211_bss_scan_width scan_width)887 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
888 				const u8 *ssid, u8 ssid_len,
889 				struct ieee80211_channel *chan,
890 				enum nl80211_bss_scan_width scan_width)
891 {
892 	struct ieee80211_local *local = sdata->local;
893 	int ret = -EBUSY;
894 	enum ieee80211_band band;
895 
896 	mutex_lock(&local->mtx);
897 
898 	/* busy scanning */
899 	if (local->scan_req)
900 		goto unlock;
901 
902 	/* fill internal scan request */
903 	if (!chan) {
904 		int i, max_n;
905 		int n_ch = 0;
906 
907 		for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
908 			if (!local->hw.wiphy->bands[band])
909 				continue;
910 
911 			max_n = local->hw.wiphy->bands[band]->n_channels;
912 			for (i = 0; i < max_n; i++) {
913 				struct ieee80211_channel *tmp_ch =
914 				    &local->hw.wiphy->bands[band]->channels[i];
915 
916 				if (tmp_ch->flags & (IEEE80211_CHAN_NO_IR |
917 						     IEEE80211_CHAN_DISABLED))
918 					continue;
919 
920 				local->int_scan_req->channels[n_ch] = tmp_ch;
921 				n_ch++;
922 			}
923 		}
924 
925 		if (WARN_ON_ONCE(n_ch == 0))
926 			goto unlock;
927 
928 		local->int_scan_req->n_channels = n_ch;
929 	} else {
930 		if (WARN_ON_ONCE(chan->flags & (IEEE80211_CHAN_NO_IR |
931 						IEEE80211_CHAN_DISABLED)))
932 			goto unlock;
933 
934 		local->int_scan_req->channels[0] = chan;
935 		local->int_scan_req->n_channels = 1;
936 	}
937 
938 	local->int_scan_req->ssids = &local->scan_ssid;
939 	local->int_scan_req->n_ssids = 1;
940 	local->int_scan_req->scan_width = scan_width;
941 	memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
942 	local->int_scan_req->ssids[0].ssid_len = ssid_len;
943 
944 	ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
945  unlock:
946 	mutex_unlock(&local->mtx);
947 	return ret;
948 }
949 
950 /*
951  * Only call this function when a scan can't be queued -- under RTNL.
952  */
ieee80211_scan_cancel(struct ieee80211_local * local)953 void ieee80211_scan_cancel(struct ieee80211_local *local)
954 {
955 	/*
956 	 * We are canceling software scan, or deferred scan that was not
957 	 * yet really started (see __ieee80211_start_scan ).
958 	 *
959 	 * Regarding hardware scan:
960 	 * - we can not call  __ieee80211_scan_completed() as when
961 	 *   SCAN_HW_SCANNING bit is set this function change
962 	 *   local->hw_scan_req to operate on 5G band, what race with
963 	 *   driver which can use local->hw_scan_req
964 	 *
965 	 * - we can not cancel scan_work since driver can schedule it
966 	 *   by ieee80211_scan_completed(..., true) to finish scan
967 	 *
968 	 * Hence we only call the cancel_hw_scan() callback, but the low-level
969 	 * driver is still responsible for calling ieee80211_scan_completed()
970 	 * after the scan was completed/aborted.
971 	 */
972 
973 	mutex_lock(&local->mtx);
974 	if (!local->scan_req)
975 		goto out;
976 
977 	/*
978 	 * We have a scan running and the driver already reported completion,
979 	 * but the worker hasn't run yet or is stuck on the mutex - mark it as
980 	 * cancelled.
981 	 */
982 	if (test_bit(SCAN_HW_SCANNING, &local->scanning) &&
983 	    test_bit(SCAN_COMPLETED, &local->scanning)) {
984 		set_bit(SCAN_HW_CANCELLED, &local->scanning);
985 		goto out;
986 	}
987 
988 	if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
989 		/*
990 		 * Make sure that __ieee80211_scan_completed doesn't trigger a
991 		 * scan on another band.
992 		 */
993 		set_bit(SCAN_HW_CANCELLED, &local->scanning);
994 		if (local->ops->cancel_hw_scan)
995 			drv_cancel_hw_scan(local,
996 				rcu_dereference_protected(local->scan_sdata,
997 						lockdep_is_held(&local->mtx)));
998 		goto out;
999 	}
1000 
1001 	/*
1002 	 * If the work is currently running, it must be blocked on
1003 	 * the mutex, but we'll set scan_sdata = NULL and it'll
1004 	 * simply exit once it acquires the mutex.
1005 	 */
1006 	cancel_delayed_work(&local->scan_work);
1007 	/* and clean up */
1008 	__ieee80211_scan_completed(&local->hw, true);
1009 out:
1010 	mutex_unlock(&local->mtx);
1011 }
1012 
__ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data * sdata,struct cfg80211_sched_scan_request * req)1013 int __ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
1014 					struct cfg80211_sched_scan_request *req)
1015 {
1016 	struct ieee80211_local *local = sdata->local;
1017 	struct ieee80211_scan_ies sched_scan_ies = {};
1018 	struct cfg80211_chan_def chandef;
1019 	int ret, i, iebufsz, num_bands = 0;
1020 	u32 rate_masks[IEEE80211_NUM_BANDS] = {};
1021 	u8 bands_used = 0;
1022 	u8 *ie;
1023 	size_t len;
1024 
1025 	iebufsz = local->scan_ies_len + req->ie_len;
1026 
1027 	lockdep_assert_held(&local->mtx);
1028 
1029 	if (!local->ops->sched_scan_start)
1030 		return -ENOTSUPP;
1031 
1032 	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
1033 		if (local->hw.wiphy->bands[i]) {
1034 			bands_used |= BIT(i);
1035 			rate_masks[i] = (u32) -1;
1036 			num_bands++;
1037 		}
1038 	}
1039 
1040 	ie = kzalloc(num_bands * iebufsz, GFP_KERNEL);
1041 	if (!ie) {
1042 		ret = -ENOMEM;
1043 		goto out;
1044 	}
1045 
1046 	ieee80211_prepare_scan_chandef(&chandef, req->scan_width);
1047 
1048 	len = ieee80211_build_preq_ies(local, ie, num_bands * iebufsz,
1049 				       &sched_scan_ies, req->ie,
1050 				       req->ie_len, bands_used,
1051 				       rate_masks, &chandef);
1052 
1053 	ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);
1054 	if (ret == 0) {
1055 		rcu_assign_pointer(local->sched_scan_sdata, sdata);
1056 		local->sched_scan_req = req;
1057 	}
1058 
1059 	kfree(ie);
1060 
1061 out:
1062 	if (ret) {
1063 		/* Clean in case of failure after HW restart or upon resume. */
1064 		RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1065 		local->sched_scan_req = NULL;
1066 	}
1067 
1068 	return ret;
1069 }
1070 
ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data * sdata,struct cfg80211_sched_scan_request * req)1071 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
1072 				       struct cfg80211_sched_scan_request *req)
1073 {
1074 	struct ieee80211_local *local = sdata->local;
1075 	int ret;
1076 
1077 	mutex_lock(&local->mtx);
1078 
1079 	if (rcu_access_pointer(local->sched_scan_sdata)) {
1080 		mutex_unlock(&local->mtx);
1081 		return -EBUSY;
1082 	}
1083 
1084 	ret = __ieee80211_request_sched_scan_start(sdata, req);
1085 
1086 	mutex_unlock(&local->mtx);
1087 	return ret;
1088 }
1089 
ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data * sdata)1090 int ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data *sdata)
1091 {
1092 	struct ieee80211_local *local = sdata->local;
1093 	int ret = 0;
1094 
1095 	mutex_lock(&local->mtx);
1096 
1097 	if (!local->ops->sched_scan_stop) {
1098 		ret = -ENOTSUPP;
1099 		goto out;
1100 	}
1101 
1102 	/* We don't want to restart sched scan anymore. */
1103 	local->sched_scan_req = NULL;
1104 
1105 	if (rcu_access_pointer(local->sched_scan_sdata)) {
1106 		ret = drv_sched_scan_stop(local, sdata);
1107 		if (!ret)
1108 			RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1109 	}
1110 out:
1111 	mutex_unlock(&local->mtx);
1112 
1113 	return ret;
1114 }
1115 
ieee80211_sched_scan_results(struct ieee80211_hw * hw)1116 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
1117 {
1118 	struct ieee80211_local *local = hw_to_local(hw);
1119 
1120 	trace_api_sched_scan_results(local);
1121 
1122 	cfg80211_sched_scan_results(hw->wiphy);
1123 }
1124 EXPORT_SYMBOL(ieee80211_sched_scan_results);
1125 
ieee80211_sched_scan_end(struct ieee80211_local * local)1126 void ieee80211_sched_scan_end(struct ieee80211_local *local)
1127 {
1128 	mutex_lock(&local->mtx);
1129 
1130 	if (!rcu_access_pointer(local->sched_scan_sdata)) {
1131 		mutex_unlock(&local->mtx);
1132 		return;
1133 	}
1134 
1135 	RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1136 
1137 	/* If sched scan was aborted by the driver. */
1138 	local->sched_scan_req = NULL;
1139 
1140 	mutex_unlock(&local->mtx);
1141 
1142 	cfg80211_sched_scan_stopped(local->hw.wiphy);
1143 }
1144 
ieee80211_sched_scan_stopped_work(struct work_struct * work)1145 void ieee80211_sched_scan_stopped_work(struct work_struct *work)
1146 {
1147 	struct ieee80211_local *local =
1148 		container_of(work, struct ieee80211_local,
1149 			     sched_scan_stopped_work);
1150 
1151 	ieee80211_sched_scan_end(local);
1152 }
1153 
ieee80211_sched_scan_stopped(struct ieee80211_hw * hw)1154 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
1155 {
1156 	struct ieee80211_local *local = hw_to_local(hw);
1157 
1158 	trace_api_sched_scan_stopped(local);
1159 
1160 	schedule_work(&local->sched_scan_stopped_work);
1161 }
1162 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);
1163