/net/mac80211/scan.c
C | 707 lines | 471 code | 131 blank | 105 comment | 91 complexity | 205722af0de2d2fc1479376ee0bdeec3 MD5 | raw file
Possible License(s): CC-BY-SA-3.0, GPL-2.0, LGPL-2.0, AGPL-1.0
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 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#include <linux/if_arp.h>
16#include <linux/rtnetlink.h>
17#include <linux/slab.h>
18#include <net/mac80211.h>
19
20#include "ieee80211_i.h"
21#include "driver-ops.h"
22#include "mesh.h"
23
24#define IEEE80211_PROBE_DELAY (HZ / 33)
25#define IEEE80211_CHANNEL_TIME (HZ / 33)
26#define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
27
28struct ieee80211_bss *
29ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
30 u8 *ssid, u8 ssid_len)
31{
32 struct cfg80211_bss *cbss;
33
34 cbss = cfg80211_get_bss(local->hw.wiphy,
35 ieee80211_get_channel(local->hw.wiphy, freq),
36 bssid, ssid, ssid_len, 0, 0);
37 if (!cbss)
38 return NULL;
39 return (void *)cbss->priv;
40}
41
42static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
43{
44 struct ieee80211_bss *bss = (void *)cbss->priv;
45
46 kfree(bss_mesh_id(bss));
47 kfree(bss_mesh_cfg(bss));
48}
49
50void ieee80211_rx_bss_put(struct ieee80211_local *local,
51 struct ieee80211_bss *bss)
52{
53 if (!bss)
54 return;
55 cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
56}
57
58static bool is_uapsd_supported(struct ieee802_11_elems *elems)
59{
60 u8 qos_info;
61
62 if (elems->wmm_info && elems->wmm_info_len == 7
63 && elems->wmm_info[5] == 1)
64 qos_info = elems->wmm_info[6];
65 else if (elems->wmm_param && elems->wmm_param_len == 24
66 && elems->wmm_param[5] == 1)
67 qos_info = elems->wmm_param[6];
68 else
69 /* no valid wmm information or parameter element found */
70 return false;
71
72 return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
73}
74
75struct ieee80211_bss *
76ieee80211_bss_info_update(struct ieee80211_local *local,
77 struct ieee80211_rx_status *rx_status,
78 struct ieee80211_mgmt *mgmt,
79 size_t len,
80 struct ieee802_11_elems *elems,
81 struct ieee80211_channel *channel,
82 bool beacon)
83{
84 struct cfg80211_bss *cbss;
85 struct ieee80211_bss *bss;
86 int clen;
87 s32 signal = 0;
88
89 if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
90 signal = rx_status->signal * 100;
91 else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
92 signal = (rx_status->signal * 100) / local->hw.max_signal;
93
94 cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
95 mgmt, len, signal, GFP_ATOMIC);
96
97 if (!cbss)
98 return NULL;
99
100 cbss->free_priv = ieee80211_rx_bss_free;
101 bss = (void *)cbss->priv;
102
103 /* save the ERP value so that it is available at association time */
104 if (elems->erp_info && elems->erp_info_len >= 1) {
105 bss->erp_value = elems->erp_info[0];
106 bss->has_erp_value = 1;
107 }
108
109 if (elems->tim) {
110 struct ieee80211_tim_ie *tim_ie =
111 (struct ieee80211_tim_ie *)elems->tim;
112 bss->dtim_period = tim_ie->dtim_period;
113 }
114
115 bss->supp_rates_len = 0;
116 if (elems->supp_rates) {
117 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
118 if (clen > elems->supp_rates_len)
119 clen = elems->supp_rates_len;
120 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
121 clen);
122 bss->supp_rates_len += clen;
123 }
124 if (elems->ext_supp_rates) {
125 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
126 if (clen > elems->ext_supp_rates_len)
127 clen = elems->ext_supp_rates_len;
128 memcpy(&bss->supp_rates[bss->supp_rates_len],
129 elems->ext_supp_rates, clen);
130 bss->supp_rates_len += clen;
131 }
132
133 bss->wmm_used = elems->wmm_param || elems->wmm_info;
134 bss->uapsd_supported = is_uapsd_supported(elems);
135
136 if (!beacon)
137 bss->last_probe_resp = jiffies;
138
139 return bss;
140}
141
142ieee80211_rx_result
143ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
144{
145 struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
146 struct ieee80211_mgmt *mgmt;
147 struct ieee80211_bss *bss;
148 u8 *elements;
149 struct ieee80211_channel *channel;
150 size_t baselen;
151 int freq;
152 __le16 fc;
153 bool presp, beacon = false;
154 struct ieee802_11_elems elems;
155
156 if (skb->len < 2)
157 return RX_DROP_UNUSABLE;
158
159 mgmt = (struct ieee80211_mgmt *) skb->data;
160 fc = mgmt->frame_control;
161
162 if (ieee80211_is_ctl(fc))
163 return RX_CONTINUE;
164
165 if (skb->len < 24)
166 return RX_DROP_MONITOR;
167
168 presp = ieee80211_is_probe_resp(fc);
169 if (presp) {
170 /* ignore ProbeResp to foreign address */
171 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
172 return RX_DROP_MONITOR;
173
174 presp = true;
175 elements = mgmt->u.probe_resp.variable;
176 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
177 } else {
178 beacon = ieee80211_is_beacon(fc);
179 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
180 elements = mgmt->u.beacon.variable;
181 }
182
183 if (!presp && !beacon)
184 return RX_CONTINUE;
185
186 if (baselen > skb->len)
187 return RX_DROP_MONITOR;
188
189 ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
190
191 if (elems.ds_params && elems.ds_params_len == 1)
192 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
193 else
194 freq = rx_status->freq;
195
196 channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
197
198 if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
199 return RX_DROP_MONITOR;
200
201 bss = ieee80211_bss_info_update(sdata->local, rx_status,
202 mgmt, skb->len, &elems,
203 channel, beacon);
204 if (bss)
205 ieee80211_rx_bss_put(sdata->local, bss);
206
207 dev_kfree_skb(skb);
208 return RX_QUEUED;
209}
210
211/* return false if no more work */
212static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
213{
214 struct cfg80211_scan_request *req = local->scan_req;
215 enum ieee80211_band band;
216 int i, ielen, n_chans;
217
218 do {
219 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
220 return false;
221
222 band = local->hw_scan_band;
223 n_chans = 0;
224 for (i = 0; i < req->n_channels; i++) {
225 if (req->channels[i]->band == band) {
226 local->hw_scan_req->channels[n_chans] =
227 req->channels[i];
228 n_chans++;
229 }
230 }
231
232 local->hw_scan_band++;
233 } while (!n_chans);
234
235 local->hw_scan_req->n_channels = n_chans;
236
237 ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
238 req->ie, req->ie_len, band);
239 local->hw_scan_req->ie_len = ielen;
240
241 return true;
242}
243
244void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
245{
246 struct ieee80211_local *local = hw_to_local(hw);
247 bool was_hw_scan;
248
249 mutex_lock(&local->scan_mtx);
250
251 /*
252 * It's ok to abort a not-yet-running scan (that
253 * we have one at all will be verified by checking
254 * local->scan_req next), but not to complete it
255 * successfully.
256 */
257 if (WARN_ON(!local->scanning && !aborted))
258 aborted = true;
259
260 if (WARN_ON(!local->scan_req)) {
261 mutex_unlock(&local->scan_mtx);
262 return;
263 }
264
265 was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
266 if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
267 ieee80211_queue_delayed_work(&local->hw,
268 &local->scan_work, 0);
269 mutex_unlock(&local->scan_mtx);
270 return;
271 }
272
273 kfree(local->hw_scan_req);
274 local->hw_scan_req = NULL;
275
276 if (local->scan_req != local->int_scan_req)
277 cfg80211_scan_done(local->scan_req, aborted);
278 local->scan_req = NULL;
279 local->scan_sdata = NULL;
280
281 local->scanning = 0;
282 local->scan_channel = NULL;
283
284 /* we only have to protect scan_req and hw/sw scan */
285 mutex_unlock(&local->scan_mtx);
286
287 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
288 if (was_hw_scan)
289 goto done;
290
291 ieee80211_configure_filter(local);
292
293 drv_sw_scan_complete(local);
294
295 ieee80211_offchannel_return(local, true);
296
297 done:
298 ieee80211_recalc_idle(local);
299 ieee80211_mlme_notify_scan_completed(local);
300 ieee80211_ibss_notify_scan_completed(local);
301 ieee80211_mesh_notify_scan_completed(local);
302 ieee80211_queue_work(&local->hw, &local->work_work);
303}
304EXPORT_SYMBOL(ieee80211_scan_completed);
305
306static int ieee80211_start_sw_scan(struct ieee80211_local *local)
307{
308 /*
309 * Hardware/driver doesn't support hw_scan, so use software
310 * scanning instead. First send a nullfunc frame with power save
311 * bit on so that AP will buffer the frames for us while we are not
312 * listening, then send probe requests to each channel and wait for
313 * the responses. After all channels are scanned, tune back to the
314 * original channel and send a nullfunc frame with power save bit
315 * off to trigger the AP to send us all the buffered frames.
316 *
317 * Note that while local->sw_scanning is true everything else but
318 * nullfunc frames and probe requests will be dropped in
319 * ieee80211_tx_h_check_assoc().
320 */
321 drv_sw_scan_start(local);
322
323 ieee80211_offchannel_stop_beaconing(local);
324
325 local->next_scan_state = SCAN_DECISION;
326 local->scan_channel_idx = 0;
327
328 drv_flush(local, false);
329
330 ieee80211_configure_filter(local);
331
332 ieee80211_queue_delayed_work(&local->hw,
333 &local->scan_work,
334 IEEE80211_CHANNEL_TIME);
335
336 return 0;
337}
338
339
340static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
341 struct cfg80211_scan_request *req)
342{
343 struct ieee80211_local *local = sdata->local;
344 int rc;
345
346 if (local->scan_req)
347 return -EBUSY;
348
349 if (!list_empty(&local->work_list)) {
350 /* wait for the work to finish/time out */
351 local->scan_req = req;
352 local->scan_sdata = sdata;
353 return 0;
354 }
355
356 if (local->ops->hw_scan) {
357 u8 *ies;
358
359 local->hw_scan_req = kmalloc(
360 sizeof(*local->hw_scan_req) +
361 req->n_channels * sizeof(req->channels[0]) +
362 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
363 req->ie_len, GFP_KERNEL);
364 if (!local->hw_scan_req)
365 return -ENOMEM;
366
367 local->hw_scan_req->ssids = req->ssids;
368 local->hw_scan_req->n_ssids = req->n_ssids;
369 ies = (u8 *)local->hw_scan_req +
370 sizeof(*local->hw_scan_req) +
371 req->n_channels * sizeof(req->channels[0]);
372 local->hw_scan_req->ie = ies;
373
374 local->hw_scan_band = 0;
375
376 /*
377 * After allocating local->hw_scan_req, we must
378 * go through until ieee80211_prep_hw_scan(), so
379 * anything that might be changed here and leave
380 * this function early must not go after this
381 * allocation.
382 */
383 }
384
385 local->scan_req = req;
386 local->scan_sdata = sdata;
387
388 if (local->ops->hw_scan)
389 __set_bit(SCAN_HW_SCANNING, &local->scanning);
390 else
391 __set_bit(SCAN_SW_SCANNING, &local->scanning);
392
393 /*
394 * Kicking off the scan need not be protected,
395 * only the scan variable stuff, since now
396 * local->scan_req is assigned and other callers
397 * will abort their scan attempts.
398 *
399 * This avoids too many locking dependencies
400 * so that the scan completed calls have more
401 * locking freedom.
402 */
403
404 ieee80211_recalc_idle(local);
405 mutex_unlock(&local->scan_mtx);
406
407 if (local->ops->hw_scan) {
408 WARN_ON(!ieee80211_prep_hw_scan(local));
409 rc = drv_hw_scan(local, local->hw_scan_req);
410 } else
411 rc = ieee80211_start_sw_scan(local);
412
413 mutex_lock(&local->scan_mtx);
414
415 if (rc) {
416 kfree(local->hw_scan_req);
417 local->hw_scan_req = NULL;
418 local->scanning = 0;
419
420 ieee80211_recalc_idle(local);
421
422 local->scan_req = NULL;
423 local->scan_sdata = NULL;
424 }
425
426 return rc;
427}
428
429static int ieee80211_scan_state_decision(struct ieee80211_local *local,
430 unsigned long *next_delay)
431{
432 bool associated = false;
433 struct ieee80211_sub_if_data *sdata;
434
435 /* if no more bands/channels left, complete scan and advance to the idle state */
436 if (local->scan_channel_idx >= local->scan_req->n_channels) {
437 ieee80211_scan_completed(&local->hw, false);
438 return 1;
439 }
440
441 /* check if at least one STA interface is associated */
442 mutex_lock(&local->iflist_mtx);
443 list_for_each_entry(sdata, &local->interfaces, list) {
444 if (!ieee80211_sdata_running(sdata))
445 continue;
446
447 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
448 if (sdata->u.mgd.associated) {
449 associated = true;
450 break;
451 }
452 }
453 }
454 mutex_unlock(&local->iflist_mtx);
455
456 if (local->scan_channel) {
457 /*
458 * we're currently scanning a different channel, let's
459 * switch back to the operating channel now if at least
460 * one interface is associated. Otherwise just scan the
461 * next channel
462 */
463 if (associated)
464 local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
465 else
466 local->next_scan_state = SCAN_SET_CHANNEL;
467 } else {
468 /*
469 * we're on the operating channel currently, let's
470 * leave that channel now to scan another one
471 */
472 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
473 }
474
475 *next_delay = 0;
476 return 0;
477}
478
479static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
480 unsigned long *next_delay)
481{
482 ieee80211_offchannel_stop_station(local);
483
484 __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
485
486 /*
487 * What if the nullfunc frames didn't arrive?
488 */
489 drv_flush(local, false);
490 if (local->ops->flush)
491 *next_delay = 0;
492 else
493 *next_delay = HZ / 10;
494
495 /* advance to the next channel to be scanned */
496 local->next_scan_state = SCAN_SET_CHANNEL;
497}
498
499static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
500 unsigned long *next_delay)
501{
502 /* switch back to the operating channel */
503 local->scan_channel = NULL;
504 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
505
506 /*
507 * Only re-enable station mode interface now; beaconing will be
508 * re-enabled once the full scan has been completed.
509 */
510 ieee80211_offchannel_return(local, false);
511
512 __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
513
514 *next_delay = HZ / 5;
515 local->next_scan_state = SCAN_DECISION;
516}
517
518static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
519 unsigned long *next_delay)
520{
521 int skip;
522 struct ieee80211_channel *chan;
523
524 skip = 0;
525 chan = local->scan_req->channels[local->scan_channel_idx];
526
527 local->scan_channel = chan;
528 if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
529 skip = 1;
530
531 /* advance state machine to next channel/band */
532 local->scan_channel_idx++;
533
534 if (skip) {
535 /* if we skip this channel return to the decision state */
536 local->next_scan_state = SCAN_DECISION;
537 return;
538 }
539
540 /*
541 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
542 * (which unfortunately doesn't say _why_ step a) is done,
543 * but it waits for the probe delay or until a frame is
544 * received - and the received frame would update the NAV).
545 * For now, we do not support waiting until a frame is
546 * received.
547 *
548 * In any case, it is not necessary for a passive scan.
549 */
550 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
551 !local->scan_req->n_ssids) {
552 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
553 local->next_scan_state = SCAN_DECISION;
554 return;
555 }
556
557 /* active scan, send probes */
558 *next_delay = IEEE80211_PROBE_DELAY;
559 local->next_scan_state = SCAN_SEND_PROBE;
560}
561
562static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
563 unsigned long *next_delay)
564{
565 int i;
566 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
567
568 for (i = 0; i < local->scan_req->n_ssids; i++)
569 ieee80211_send_probe_req(
570 sdata, NULL,
571 local->scan_req->ssids[i].ssid,
572 local->scan_req->ssids[i].ssid_len,
573 local->scan_req->ie, local->scan_req->ie_len);
574
575 /*
576 * After sending probe requests, wait for probe responses
577 * on the channel.
578 */
579 *next_delay = IEEE80211_CHANNEL_TIME;
580 local->next_scan_state = SCAN_DECISION;
581}
582
583void ieee80211_scan_work(struct work_struct *work)
584{
585 struct ieee80211_local *local =
586 container_of(work, struct ieee80211_local, scan_work.work);
587 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
588 unsigned long next_delay = 0;
589
590 mutex_lock(&local->scan_mtx);
591 if (!sdata || !local->scan_req) {
592 mutex_unlock(&local->scan_mtx);
593 return;
594 }
595
596 if (local->hw_scan_req) {
597 int rc = drv_hw_scan(local, local->hw_scan_req);
598 mutex_unlock(&local->scan_mtx);
599 if (rc)
600 ieee80211_scan_completed(&local->hw, true);
601 return;
602 }
603
604 if (local->scan_req && !local->scanning) {
605 struct cfg80211_scan_request *req = local->scan_req;
606 int rc;
607
608 local->scan_req = NULL;
609 local->scan_sdata = NULL;
610
611 rc = __ieee80211_start_scan(sdata, req);
612 mutex_unlock(&local->scan_mtx);
613
614 if (rc)
615 ieee80211_scan_completed(&local->hw, true);
616 return;
617 }
618
619 mutex_unlock(&local->scan_mtx);
620
621 /*
622 * Avoid re-scheduling when the sdata is going away.
623 */
624 if (!ieee80211_sdata_running(sdata)) {
625 ieee80211_scan_completed(&local->hw, true);
626 return;
627 }
628
629 /*
630 * as long as no delay is required advance immediately
631 * without scheduling a new work
632 */
633 do {
634 switch (local->next_scan_state) {
635 case SCAN_DECISION:
636 if (ieee80211_scan_state_decision(local, &next_delay))
637 return;
638 break;
639 case SCAN_SET_CHANNEL:
640 ieee80211_scan_state_set_channel(local, &next_delay);
641 break;
642 case SCAN_SEND_PROBE:
643 ieee80211_scan_state_send_probe(local, &next_delay);
644 break;
645 case SCAN_LEAVE_OPER_CHANNEL:
646 ieee80211_scan_state_leave_oper_channel(local, &next_delay);
647 break;
648 case SCAN_ENTER_OPER_CHANNEL:
649 ieee80211_scan_state_enter_oper_channel(local, &next_delay);
650 break;
651 }
652 } while (next_delay == 0);
653
654 ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
655}
656
657int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
658 struct cfg80211_scan_request *req)
659{
660 int res;
661
662 mutex_lock(&sdata->local->scan_mtx);
663 res = __ieee80211_start_scan(sdata, req);
664 mutex_unlock(&sdata->local->scan_mtx);
665
666 return res;
667}
668
669int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
670 const u8 *ssid, u8 ssid_len)
671{
672 struct ieee80211_local *local = sdata->local;
673 int ret = -EBUSY;
674
675 mutex_lock(&local->scan_mtx);
676
677 /* busy scanning */
678 if (local->scan_req)
679 goto unlock;
680
681 memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
682 local->int_scan_req->ssids[0].ssid_len = ssid_len;
683
684 ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
685 unlock:
686 mutex_unlock(&local->scan_mtx);
687 return ret;
688}
689
690void ieee80211_scan_cancel(struct ieee80211_local *local)
691{
692 bool abortscan;
693
694 cancel_delayed_work_sync(&local->scan_work);
695
696 /*
697 * Only call this function when a scan can't be
698 * queued -- mostly at suspend under RTNL.
699 */
700 mutex_lock(&local->scan_mtx);
701 abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
702 (!local->scanning && local->scan_req);
703 mutex_unlock(&local->scan_mtx);
704
705 if (abortscan)
706 ieee80211_scan_completed(&local->hw, true);
707}