scan.c 15.3 KB
Newer Older
1
/*
2
3
 * Scanning implementation
 *
4
5
6
7
8
9
10
11
12
13
14
 * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
 * Copyright 2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
 * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

15
/* TODO: figure out how to avoid that the "current BSS" expires */
16

17
18
#include <linux/wireless.h>
#include <linux/if_arp.h>
19
#include <linux/rtnetlink.h>
20
21
22
23
#include <net/mac80211.h>
#include <net/iw_handler.h>

#include "ieee80211_i.h"
24
#include "mesh.h"
25
26
27
28
29

#define IEEE80211_PROBE_DELAY (HZ / 33)
#define IEEE80211_CHANNEL_TIME (HZ / 33)
#define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)

30
struct ieee80211_bss *
31
32
33
ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
		     u8 *ssid, u8 ssid_len)
{
34
35
36
37
38
	return (void *)cfg80211_get_bss(local->hw.wiphy,
					ieee80211_get_channel(local->hw.wiphy,
							      freq),
					bssid, ssid, ssid_len,
					0, 0);
39
40
}

41
static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
42
{
43
	struct ieee80211_bss *bss = (void *)cbss;
44
45
46
47
48
49

	kfree(bss_mesh_id(bss));
	kfree(bss_mesh_cfg(bss));
}

void ieee80211_rx_bss_put(struct ieee80211_local *local,
50
			  struct ieee80211_bss *bss)
51
{
52
	cfg80211_put_bss((struct cfg80211_bss *)bss);
53
54
}

55
struct ieee80211_bss *
56
57
58
59
60
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,
61
62
			  struct ieee80211_channel *channel,
			  bool beacon)
63
{
64
	struct ieee80211_bss *bss;
65
	int clen;
66
67
	s32 signal = 0;

Johannes Berg's avatar
Johannes Berg committed
68
	if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
69
		signal = rx_status->signal * 100;
Johannes Berg's avatar
Johannes Berg committed
70
	else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
71
72
		signal = (rx_status->signal * 100) / local->hw.max_signal;

73
	bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
Johannes Berg's avatar
Johannes Berg committed
74
						mgmt, len, signal, GFP_ATOMIC);
75

76
77
78
79
	if (!bss)
		return NULL;

	bss->cbss.free_priv = ieee80211_rx_bss_free;
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121

	/* save the ERP value so that it is available at association time */
	if (elems->erp_info && elems->erp_info_len >= 1) {
		bss->erp_value = elems->erp_info[0];
		bss->has_erp_value = 1;
	}

	if (elems->tim) {
		struct ieee80211_tim_ie *tim_ie =
			(struct ieee80211_tim_ie *)elems->tim;
		bss->dtim_period = tim_ie->dtim_period;
	}

	/* set default value for buggy APs */
	if (!elems->tim || bss->dtim_period == 0)
		bss->dtim_period = 1;

	bss->supp_rates_len = 0;
	if (elems->supp_rates) {
		clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
		if (clen > elems->supp_rates_len)
			clen = elems->supp_rates_len;
		memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
		       clen);
		bss->supp_rates_len += clen;
	}
	if (elems->ext_supp_rates) {
		clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
		if (clen > elems->ext_supp_rates_len)
			clen = elems->ext_supp_rates_len;
		memcpy(&bss->supp_rates[bss->supp_rates_len],
		       elems->ext_supp_rates, clen);
		bss->supp_rates_len += clen;
	}

	bss->wmm_used = elems->wmm_param || elems->wmm_info;

	if (!beacon)
		bss->last_probe_resp = jiffies;

	return bss;
}
122

123
124
125
126
127
128
129
130
void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid,
			     int freq, u8 *ssid, u8 ssid_len)
{
	struct ieee80211_bss *bss;
	struct ieee80211_local *local = sdata->local;

	bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
	if (bss) {
131
		cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
132
133
134
135
		ieee80211_rx_bss_put(local, bss);
	}
}

136
ieee80211_rx_result
137
138
ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
		  struct ieee80211_rx_status *rx_status)
139
140
{
	struct ieee80211_mgmt *mgmt;
141
	struct ieee80211_bss *bss;
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
	u8 *elements;
	struct ieee80211_channel *channel;
	size_t baselen;
	int freq;
	__le16 fc;
	bool presp, beacon = false;
	struct ieee802_11_elems elems;

	if (skb->len < 2)
		return RX_DROP_UNUSABLE;

	mgmt = (struct ieee80211_mgmt *) skb->data;
	fc = mgmt->frame_control;

	if (ieee80211_is_ctl(fc))
		return RX_CONTINUE;

	if (skb->len < 24)
		return RX_DROP_MONITOR;

	presp = ieee80211_is_probe_resp(fc);
	if (presp) {
		/* ignore ProbeResp to foreign address */
		if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
			return RX_DROP_MONITOR;

		presp = true;
		elements = mgmt->u.probe_resp.variable;
		baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
	} else {
		beacon = ieee80211_is_beacon(fc);
		baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
		elements = mgmt->u.beacon.variable;
	}

	if (!presp && !beacon)
		return RX_CONTINUE;

	if (baselen > skb->len)
		return RX_DROP_MONITOR;

	ieee802_11_parse_elems(elements, skb->len - baselen, &elems);

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

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

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

	bss = ieee80211_bss_info_update(sdata->local, rx_status,
					mgmt, skb->len, &elems,
197
					channel, beacon);
198
199
	if (bss)
		ieee80211_rx_bss_put(sdata->local, bss);
200
201
202
203
204

	dev_kfree_skb(skb);
	return RX_QUEUED;
}

205
206
207
208
209
210
211
212
213
214
215
216
void ieee80211_scan_failed(struct ieee80211_local *local)
{
	if (WARN_ON(!local->scan_req))
		return;

	/* notify cfg80211 about the failed scan */
	if (local->scan_req != &local->int_scan_req)
		cfg80211_scan_done(local->scan_req, true);

	local->scan_req = NULL;
}

217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
/*
 * inform AP that we will go to sleep so that it will buffer the frames
 * while we scan
 */
static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_local *local = sdata->local;
	bool ps = false;

	/* FIXME: what to do when local->pspolling is true? */

	del_timer_sync(&local->dynamic_ps_timer);
	cancel_work_sync(&local->dynamic_ps_enable_work);

	if (local->hw.conf.flags & IEEE80211_CONF_PS) {
		ps = true;
		local->hw.conf.flags &= ~IEEE80211_CONF_PS;
		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
	}

	if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
		/*
		 * If power save was enabled, no need to send a nullfunc
		 * frame because AP knows that we are sleeping. But if the
		 * hardware is creating the nullfunc frame for power save
		 * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
		 * enabled) and power save was enabled, the firmware just
		 * sent a null frame with power save disabled. So we need
		 * to send a new nullfunc frame to inform the AP that we
		 * are again sleeping.
		 */
		ieee80211_send_nullfunc(local, sdata, 1);
}

/* inform AP that we are awake again, unless power save is enabled */
static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_local *local = sdata->local;

	if (!local->powersave)
		ieee80211_send_nullfunc(local, sdata, 0);
	else {
		/*
		 * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
		 * will send a nullfunc frame with the powersave bit set
		 * even though the AP already knows that we are sleeping.
		 * This could be avoided by sending a null frame with power
		 * save bit disabled before enabling the power save, but
		 * this doesn't gain anything.
		 *
		 * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
		 * to send a nullfunc frame because AP already knows that
		 * we are sleeping, let's just enable power save mode in
		 * hardware.
		 */
		local->hw.conf.flags |= IEEE80211_CONF_PS;
		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
	}
}

277
void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
278
279
280
281
{
	struct ieee80211_local *local = hw_to_local(hw);
	struct ieee80211_sub_if_data *sdata;

282
	if (WARN_ON(!local->hw_scanning && !local->sw_scanning))
283
284
		return;

285
286
	if (WARN_ON(!local->scan_req))
		return;
287

288
289
290
291
292
	if (local->scan_req != &local->int_scan_req)
		cfg80211_scan_done(local->scan_req, aborted);
	local->scan_req = NULL;

	local->last_scan_completed = jiffies;
293

294
295
	if (local->hw_scanning) {
		local->hw_scanning = false;
296
297
298
299
300
301
		/*
		 * Somebody might have requested channel change during scan
		 * that we won't have acted upon, try now. ieee80211_hw_config
		 * will set the flag based on actual changes.
		 */
		ieee80211_hw_config(local, 0);
302
303
304
		goto done;
	}

305
	local->sw_scanning = false;
306
	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
307
308
309
310
311
312
313
314
315
316
317
318
319

	netif_tx_lock_bh(local->mdev);
	netif_addr_lock(local->mdev);
	local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
	local->ops->configure_filter(local_to_hw(local),
				     FIF_BCN_PRBRESP_PROMISC,
				     &local->filter_flags,
				     local->mdev->mc_count,
				     local->mdev->mc_list);

	netif_addr_unlock(local->mdev);
	netif_tx_unlock_bh(local->mdev);

320
321
322
	if (local->ops->sw_scan_complete)
		local->ops->sw_scan_complete(local_to_hw(local));

323
324
	mutex_lock(&local->iflist_mtx);
	list_for_each_entry(sdata, &local->interfaces, list) {
325
326
327
		if (!netif_running(sdata->dev))
			continue;

328
		/* Tell AP we're back */
329
		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
330
			if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
331
				ieee80211_scan_ps_disable(sdata);
332
333
334
335
				netif_tx_wake_all_queues(sdata->dev);
			}
		} else
			netif_tx_wake_all_queues(sdata->dev);
336

337
338
339
340
341
342
		/* re-enable beaconing */
		if (sdata->vif.type == NL80211_IFTYPE_AP ||
		    sdata->vif.type == NL80211_IFTYPE_ADHOC ||
		    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
			ieee80211_if_config(sdata,
					    IEEE80211_IFCC_BEACON_ENABLED);
343
	}
344
	mutex_unlock(&local->iflist_mtx);
345
346
347

 done:
	ieee80211_mlme_notify_scan_completed(local);
348
	ieee80211_ibss_notify_scan_completed(local);
349
	ieee80211_mesh_notify_scan_completed(local);
350
351
352
}
EXPORT_SYMBOL(ieee80211_scan_completed);

353
void ieee80211_scan_work(struct work_struct *work)
354
355
356
357
358
{
	struct ieee80211_local *local =
		container_of(work, struct ieee80211_local, scan_work.work);
	struct ieee80211_sub_if_data *sdata = local->scan_sdata;
	struct ieee80211_channel *chan;
359
	int skip, i;
360
361
	unsigned long next_delay = 0;

362
363
364
365
	/*
	 * Avoid re-scheduling when the sdata is going away.
	 */
	if (!netif_running(sdata->dev))
366
367
368
369
370
		return;

	switch (local->scan_state) {
	case SCAN_SET_CHANNEL:
		/* if no more bands/channels left, complete scan */
371
372
		if (local->scan_channel_idx >= local->scan_req->n_channels) {
			ieee80211_scan_completed(local_to_hw(local), false);
373
374
375
			return;
		}
		skip = 0;
376
		chan = local->scan_req->channels[local->scan_channel_idx];
377
378

		if (chan->flags & IEEE80211_CHAN_DISABLED ||
379
		    (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
380
381
382
383
384
		     chan->flags & IEEE80211_CHAN_NO_IBSS))
			skip = 1;

		if (!skip) {
			local->scan_channel = chan;
385
386
			if (ieee80211_hw_config(local,
						IEEE80211_CONF_CHANGE_CHANNEL))
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
				skip = 1;
		}

		/* advance state machine to next channel/band */
		local->scan_channel_idx++;

		if (skip)
			break;

		next_delay = IEEE80211_PROBE_DELAY +
			     usecs_to_jiffies(local->hw.channel_change_time);
		local->scan_state = SCAN_SEND_PROBE;
		break;
	case SCAN_SEND_PROBE:
		next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
		local->scan_state = SCAN_SET_CHANNEL;

404
405
		if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
		    !local->scan_req->n_ssids)
406
			break;
407
408
409
410
		for (i = 0; i < local->scan_req->n_ssids; i++)
			ieee80211_send_probe_req(
				sdata, NULL,
				local->scan_req->ssids[i].ssid,
411
412
				local->scan_req->ssids[i].ssid_len,
				local->scan_req->ie, local->scan_req->ie_len);
413
414
415
416
		next_delay = IEEE80211_CHANNEL_TIME;
		break;
	}

417
418
	queue_delayed_work(local->hw.workqueue, &local->scan_work,
			   next_delay);
419
420
421
}


422
int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
423
			 struct cfg80211_scan_request *req)
424
425
426
427
{
	struct ieee80211_local *local = scan_sdata->local;
	struct ieee80211_sub_if_data *sdata;

428
	if (!req)
429
430
		return -EINVAL;

431
432
433
434
435
	if (local->scan_req && local->scan_req != req)
		return -EBUSY;

	local->scan_req = req;

436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
	/* MLME-SCAN.request (page 118)  page 144 (11.1.3.1)
	 * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS
	 * BSSID: MACAddress
	 * SSID
	 * ScanType: ACTIVE, PASSIVE
	 * ProbeDelay: delay (in microseconds) to be used prior to transmitting
	 *    a Probe frame during active scanning
	 * ChannelList
	 * MinChannelTime (>= ProbeDelay), in TU
	 * MaxChannelTime: (>= MinChannelTime), in TU
	 */

	 /* MLME-SCAN.confirm
	  * BSSDescriptionSet
	  * ResultCode: SUCCESS, INVALID_PARAMETERS
	 */

453
	if (local->sw_scanning || local->hw_scanning) {
454
455
456
457
458
459
		if (local->scan_sdata == scan_sdata)
			return 0;
		return -EBUSY;
	}

	if (local->ops->hw_scan) {
460
461
		int rc;

462
		local->hw_scanning = true;
463
		rc = local->ops->hw_scan(local_to_hw(local), req);
464
		if (rc) {
465
			local->hw_scanning = false;
466
			return rc;
467
		}
468
469
		local->scan_sdata = scan_sdata;
		return 0;
470
471
	}

472
473
474
475
476
477
478
479
480
481
482
483
484
	/*
	 * Hardware/driver doesn't support hw_scan, so use software
	 * scanning instead. First send a nullfunc frame with power save
	 * bit on so that AP will buffer the frames for us while we are not
	 * listening, then send probe requests to each channel and wait for
	 * the responses. After all channels are scanned, tune back to the
	 * original channel and send a nullfunc frame with power save bit
	 * off to trigger the AP to send us all the buffered frames.
	 *
	 * Note that while local->sw_scanning is true everything else but
	 * nullfunc frames and probe requests will be dropped in
	 * ieee80211_tx_h_check_assoc().
	 */
485
	local->sw_scanning = true;
486
487
	if (local->ops->sw_scan_start)
		local->ops->sw_scan_start(local_to_hw(local));
488

489
490
	mutex_lock(&local->iflist_mtx);
	list_for_each_entry(sdata, &local->interfaces, list) {
491
492
493
		if (!netif_running(sdata->dev))
			continue;

494
495
496
497
498
499
		/* disable beaconing */
		if (sdata->vif.type == NL80211_IFTYPE_AP ||
		    sdata->vif.type == NL80211_IFTYPE_ADHOC ||
		    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
			ieee80211_if_config(sdata,
					    IEEE80211_IFCC_BEACON_ENABLED);
500

501
		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
502
			if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
503
				netif_tx_stop_all_queues(sdata->dev);
504
				ieee80211_scan_ps_enable(sdata);
505
506
507
508
			}
		} else
			netif_tx_stop_all_queues(sdata->dev);
	}
509
	mutex_unlock(&local->iflist_mtx);
510
511
512
513

	local->scan_state = SCAN_SET_CHANNEL;
	local->scan_channel_idx = 0;
	local->scan_sdata = scan_sdata;
514
	local->scan_req = req;
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532

	netif_addr_lock_bh(local->mdev);
	local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
	local->ops->configure_filter(local_to_hw(local),
				     FIF_BCN_PRBRESP_PROMISC,
				     &local->filter_flags,
				     local->mdev->mc_count,
				     local->mdev->mc_list);
	netif_addr_unlock_bh(local->mdev);

	/* TODO: start scan as soon as all nullfunc frames are ACKed */
	queue_delayed_work(local->hw.workqueue, &local->scan_work,
			   IEEE80211_CHANNEL_TIME);

	return 0;
}


533
int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
534
			   struct cfg80211_scan_request *req)
535
536
{
	struct ieee80211_local *local = sdata->local;
537
	struct ieee80211_if_managed *ifmgd;
538

539
540
541
542
543
544
545
546
	if (!req)
		return -EINVAL;

	if (local->scan_req && local->scan_req != req)
		return -EBUSY;

	local->scan_req = req;

547
	if (sdata->vif.type != NL80211_IFTYPE_STATION)
548
		return ieee80211_start_scan(sdata, req);
549

Johannes Berg's avatar
Johannes Berg committed
550
551
552
553
554
555
	/*
	 * STA has a state machine that might need to defer scanning
	 * while it's trying to associate/authenticate, therefore we
	 * queue it up to the state machine in that case.
	 */

556
	if (local->sw_scanning || local->hw_scanning) {
557
558
559
560
561
		if (local->scan_sdata == sdata)
			return 0;
		return -EBUSY;
	}

562
563
564
	ifmgd = &sdata->u.mgd;
	set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
	queue_work(local->hw.workqueue, &ifmgd->work);
Johannes Berg's avatar
Johannes Berg committed
565

566
567
	return 0;
}