summaryrefslogtreecommitdiff
path: root/net/mac80211/scan.c
blob: 46f35dc6accb76066873bb1dd621bf8701775c2f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
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
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
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
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
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
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
/*
 * Scanning implementation
 *
 * 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.
 */

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

#include <linux/wireless.h>
#include <linux/if_arp.h>
#include <linux/rtnetlink.h>
#include <net/mac80211.h>
#include <net/iw_handler.h>

#include "ieee80211_i.h"
#include "mesh.h"

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

struct ieee80211_bss *
ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
		     u8 *ssid, u8 ssid_len)
{
	return (void *)cfg80211_get_bss(local->hw.wiphy,
					ieee80211_get_channel(local->hw.wiphy,
							      freq),
					bssid, ssid, ssid_len,
					0, 0);
}

static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
{
	struct ieee80211_bss *bss = (void *)cbss;

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

void ieee80211_rx_bss_put(struct ieee80211_local *local,
			  struct ieee80211_bss *bss)
{
	cfg80211_put_bss((struct cfg80211_bss *)bss);
}

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,
			  bool beacon)
{
	struct ieee80211_bss *bss;
	int clen;
	s32 signal = 0;

	if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
		signal = rx_status->signal * 100;
	else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
		signal = (rx_status->signal * 100) / local->hw.max_signal;

	bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
						mgmt, len, signal, GFP_ATOMIC);

	if (!bss)
		return NULL;

	bss->cbss.free_priv = ieee80211_rx_bss_free;

	/* 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;
}

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) {
		cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
		ieee80211_rx_bss_put(local, bss);
	}
}

ieee80211_rx_result
ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
		  struct ieee80211_rx_status *rx_status)
{
	struct ieee80211_mgmt *mgmt;
	struct ieee80211_bss *bss;
	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,
					channel, beacon);
	if (bss)
		ieee80211_rx_bss_put(sdata->local, bss);

	dev_kfree_skb(skb);
	return RX_QUEUED;
}

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;
}

void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
{
	struct ieee80211_local *local = hw_to_local(hw);
	struct ieee80211_sub_if_data *sdata;

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

	if (WARN_ON(!local->scan_req))
		return;

	if (local->scan_req != &local->int_scan_req)
		cfg80211_scan_done(local->scan_req, aborted);
	local->scan_req = NULL;

	local->last_scan_completed = jiffies;

	if (local->hw_scanning) {
		local->hw_scanning = false;
		/*
		 * 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);
		goto done;
	}

	local->sw_scanning = false;
	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);

	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);

	if (local->ops->sw_scan_complete)
		local->ops->sw_scan_complete(local_to_hw(local));

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

		/* Tell AP we're back */
		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
			if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
				ieee80211_send_nullfunc(local, sdata, 0);
				netif_tx_wake_all_queues(sdata->dev);
			}
		} else
			netif_tx_wake_all_queues(sdata->dev);

		/* 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);
	}
	mutex_unlock(&local->iflist_mtx);

 done:
	ieee80211_mlme_notify_scan_completed(local);
	ieee80211_ibss_notify_scan_completed(local);
	ieee80211_mesh_notify_scan_completed(local);
}
EXPORT_SYMBOL(ieee80211_scan_completed);

void ieee80211_scan_work(struct work_struct *work)
{
	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;
	int skip, i;
	unsigned long next_delay = 0;

	/*
	 * Avoid re-scheduling when the sdata is going away.
	 */
	if (!netif_running(sdata->dev))
		return;

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

		if (chan->flags & IEEE80211_CHAN_DISABLED ||
		    (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
		     chan->flags & IEEE80211_CHAN_NO_IBSS))
			skip = 1;

		if (!skip) {
			local->scan_channel = chan;
			if (ieee80211_hw_config(local,
						IEEE80211_CONF_CHANGE_CHANNEL))
				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;

		if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
		    !local->scan_req->n_ssids)
			break;
		for (i = 0; i < local->scan_req->n_ssids; i++)
			ieee80211_send_probe_req(
				sdata, NULL,
				local->scan_req->ssids[i].ssid,
				local->scan_req->ssids[i].ssid_len,
				local->scan_req->ie, local->scan_req->ie_len);
		next_delay = IEEE80211_CHANNEL_TIME;
		break;
	}

	queue_delayed_work(local->hw.workqueue, &local->scan_work,
			   next_delay);
}


int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
			 struct cfg80211_scan_request *req)
{
	struct ieee80211_local *local = scan_sdata->local;
	struct ieee80211_sub_if_data *sdata;

	if (!req)
		return -EINVAL;

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

	local->scan_req = req;

	/* 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
	 */

	if (local->sw_scanning || local->hw_scanning) {
		if (local->scan_sdata == scan_sdata)
			return 0;
		return -EBUSY;
	}

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

		local->hw_scanning = true;
		rc = local->ops->hw_scan(local_to_hw(local), req);
		if (rc) {
			local->hw_scanning = false;
			return rc;
		}
		local->scan_sdata = scan_sdata;
		return 0;
	}

	/*
	 * 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().
	 */
	local->sw_scanning = true;
	if (local->ops->sw_scan_start)
		local->ops->sw_scan_start(local_to_hw(local));

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

		/* 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);

		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
			if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
				netif_tx_stop_all_queues(sdata->dev);
				ieee80211_send_nullfunc(local, sdata, 1);
			}
		} else
			netif_tx_stop_all_queues(sdata->dev);
	}
	mutex_unlock(&local->iflist_mtx);

	local->scan_state = SCAN_SET_CHANNEL;
	local->scan_channel_idx = 0;
	local->scan_sdata = scan_sdata;
	local->scan_req = req;

	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;
}


int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
			   struct cfg80211_scan_request *req)
{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_if_managed *ifmgd;

	if (!req)
		return -EINVAL;

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

	local->scan_req = req;

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

	/*
	 * 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.
	 */

	if (local->sw_scanning || local->hw_scanning) {
		if (local->scan_sdata == sdata)
			return 0;
		return -EBUSY;
	}

	ifmgd = &sdata->u.mgd;
	set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
	queue_work(local->hw.workqueue, &ifmgd->work);

	return 0;
}