mac80211: fix a few work bugs
[linux-2.6.git] / net / mac80211 / scan.c
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 <net/mac80211.h>
18
19 #include "ieee80211_i.h"
20 #include "driver-ops.h"
21 #include "mesh.h"
22
23 #define IEEE80211_PROBE_DELAY (HZ / 33)
24 #define IEEE80211_CHANNEL_TIME (HZ / 33)
25 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
26
27 struct ieee80211_bss *
28 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
29                      u8 *ssid, u8 ssid_len)
30 {
31         struct cfg80211_bss *cbss;
32
33         cbss = cfg80211_get_bss(local->hw.wiphy,
34                                 ieee80211_get_channel(local->hw.wiphy, freq),
35                                 bssid, ssid, ssid_len, 0, 0);
36         if (!cbss)
37                 return NULL;
38         return (void *)cbss->priv;
39 }
40
41 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
42 {
43         struct ieee80211_bss *bss = (void *)cbss->priv;
44
45         kfree(bss_mesh_id(bss));
46         kfree(bss_mesh_cfg(bss));
47 }
48
49 void ieee80211_rx_bss_put(struct ieee80211_local *local,
50                           struct ieee80211_bss *bss)
51 {
52         if (!bss)
53                 return;
54         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
55 }
56
57 struct ieee80211_bss *
58 ieee80211_bss_info_update(struct ieee80211_local *local,
59                           struct ieee80211_rx_status *rx_status,
60                           struct ieee80211_mgmt *mgmt,
61                           size_t len,
62                           struct ieee802_11_elems *elems,
63                           struct ieee80211_channel *channel,
64                           bool beacon)
65 {
66         struct cfg80211_bss *cbss;
67         struct ieee80211_bss *bss;
68         int clen;
69         s32 signal = 0;
70
71         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
72                 signal = rx_status->signal * 100;
73         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
74                 signal = (rx_status->signal * 100) / local->hw.max_signal;
75
76         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
77                                          mgmt, len, signal, GFP_ATOMIC);
78
79         if (!cbss)
80                 return NULL;
81
82         cbss->free_priv = ieee80211_rx_bss_free;
83         bss = (void *)cbss->priv;
84
85         /* save the ERP value so that it is available at association time */
86         if (elems->erp_info && elems->erp_info_len >= 1) {
87                 bss->erp_value = elems->erp_info[0];
88                 bss->has_erp_value = 1;
89         }
90
91         if (elems->tim) {
92                 struct ieee80211_tim_ie *tim_ie =
93                         (struct ieee80211_tim_ie *)elems->tim;
94                 bss->dtim_period = tim_ie->dtim_period;
95         }
96
97         /* set default value for buggy AP/no TIM element */
98         if (bss->dtim_period == 0)
99                 bss->dtim_period = 1;
100
101         bss->supp_rates_len = 0;
102         if (elems->supp_rates) {
103                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
104                 if (clen > elems->supp_rates_len)
105                         clen = elems->supp_rates_len;
106                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
107                        clen);
108                 bss->supp_rates_len += clen;
109         }
110         if (elems->ext_supp_rates) {
111                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
112                 if (clen > elems->ext_supp_rates_len)
113                         clen = elems->ext_supp_rates_len;
114                 memcpy(&bss->supp_rates[bss->supp_rates_len],
115                        elems->ext_supp_rates, clen);
116                 bss->supp_rates_len += clen;
117         }
118
119         bss->wmm_used = elems->wmm_param || elems->wmm_info;
120
121         if (!beacon)
122                 bss->last_probe_resp = jiffies;
123
124         return bss;
125 }
126
127 ieee80211_rx_result
128 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
129 {
130         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
131         struct ieee80211_mgmt *mgmt;
132         struct ieee80211_bss *bss;
133         u8 *elements;
134         struct ieee80211_channel *channel;
135         size_t baselen;
136         int freq;
137         __le16 fc;
138         bool presp, beacon = false;
139         struct ieee802_11_elems elems;
140
141         if (skb->len < 2)
142                 return RX_DROP_UNUSABLE;
143
144         mgmt = (struct ieee80211_mgmt *) skb->data;
145         fc = mgmt->frame_control;
146
147         if (ieee80211_is_ctl(fc))
148                 return RX_CONTINUE;
149
150         if (skb->len < 24)
151                 return RX_DROP_MONITOR;
152
153         presp = ieee80211_is_probe_resp(fc);
154         if (presp) {
155                 /* ignore ProbeResp to foreign address */
156                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
157                         return RX_DROP_MONITOR;
158
159                 presp = true;
160                 elements = mgmt->u.probe_resp.variable;
161                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
162         } else {
163                 beacon = ieee80211_is_beacon(fc);
164                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
165                 elements = mgmt->u.beacon.variable;
166         }
167
168         if (!presp && !beacon)
169                 return RX_CONTINUE;
170
171         if (baselen > skb->len)
172                 return RX_DROP_MONITOR;
173
174         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
175
176         if (elems.ds_params && elems.ds_params_len == 1)
177                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
178         else
179                 freq = rx_status->freq;
180
181         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
182
183         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
184                 return RX_DROP_MONITOR;
185
186         bss = ieee80211_bss_info_update(sdata->local, rx_status,
187                                         mgmt, skb->len, &elems,
188                                         channel, beacon);
189         if (bss)
190                 ieee80211_rx_bss_put(sdata->local, bss);
191
192         dev_kfree_skb(skb);
193         return RX_QUEUED;
194 }
195
196 /* return false if no more work */
197 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
198 {
199         struct cfg80211_scan_request *req = local->scan_req;
200         enum ieee80211_band band;
201         int i, ielen, n_chans;
202
203         do {
204                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
205                         return false;
206
207                 band = local->hw_scan_band;
208                 n_chans = 0;
209                 for (i = 0; i < req->n_channels; i++) {
210                         if (req->channels[i]->band == band) {
211                                 local->hw_scan_req->channels[n_chans] =
212                                                         req->channels[i];
213                                 n_chans++;
214                         }
215                 }
216
217                 local->hw_scan_band++;
218         } while (!n_chans);
219
220         local->hw_scan_req->n_channels = n_chans;
221
222         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
223                                          req->ie, req->ie_len, band);
224         local->hw_scan_req->ie_len = ielen;
225
226         return true;
227 }
228
229 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
230 {
231         struct ieee80211_local *local = hw_to_local(hw);
232         bool was_hw_scan;
233
234         mutex_lock(&local->scan_mtx);
235
236         /*
237          * It's ok to abort a not-yet-running scan (that
238          * we have one at all will be verified by checking
239          * local->scan_req next), but not to complete it
240          * successfully.
241          */
242         if (WARN_ON(!local->scanning && !aborted))
243                 aborted = true;
244
245         if (WARN_ON(!local->scan_req)) {
246                 mutex_unlock(&local->scan_mtx);
247                 return;
248         }
249
250         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
251         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
252                 ieee80211_queue_delayed_work(&local->hw,
253                                              &local->scan_work, 0);
254                 mutex_unlock(&local->scan_mtx);
255                 return;
256         }
257
258         kfree(local->hw_scan_req);
259         local->hw_scan_req = NULL;
260
261         if (local->scan_req != local->int_scan_req)
262                 cfg80211_scan_done(local->scan_req, aborted);
263         local->scan_req = NULL;
264         local->scan_sdata = NULL;
265
266         local->scanning = 0;
267         local->scan_channel = NULL;
268
269         /* we only have to protect scan_req and hw/sw scan */
270         mutex_unlock(&local->scan_mtx);
271
272         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
273         if (was_hw_scan)
274                 goto done;
275
276         ieee80211_configure_filter(local);
277
278         drv_sw_scan_complete(local);
279
280         ieee80211_offchannel_return(local, true);
281
282  done:
283         ieee80211_recalc_idle(local);
284         ieee80211_mlme_notify_scan_completed(local);
285         ieee80211_ibss_notify_scan_completed(local);
286         ieee80211_mesh_notify_scan_completed(local);
287         ieee80211_queue_work(&local->hw, &local->work_work);
288 }
289 EXPORT_SYMBOL(ieee80211_scan_completed);
290
291 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
292 {
293         /*
294          * Hardware/driver doesn't support hw_scan, so use software
295          * scanning instead. First send a nullfunc frame with power save
296          * bit on so that AP will buffer the frames for us while we are not
297          * listening, then send probe requests to each channel and wait for
298          * the responses. After all channels are scanned, tune back to the
299          * original channel and send a nullfunc frame with power save bit
300          * off to trigger the AP to send us all the buffered frames.
301          *
302          * Note that while local->sw_scanning is true everything else but
303          * nullfunc frames and probe requests will be dropped in
304          * ieee80211_tx_h_check_assoc().
305          */
306         drv_sw_scan_start(local);
307
308         ieee80211_offchannel_stop_beaconing(local);
309
310         local->next_scan_state = SCAN_DECISION;
311         local->scan_channel_idx = 0;
312
313         drv_flush(local, false);
314
315         ieee80211_configure_filter(local);
316
317         ieee80211_queue_delayed_work(&local->hw,
318                                      &local->scan_work,
319                                      IEEE80211_CHANNEL_TIME);
320
321         return 0;
322 }
323
324
325 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
326                                   struct cfg80211_scan_request *req)
327 {
328         struct ieee80211_local *local = sdata->local;
329         int rc;
330
331         if (local->scan_req)
332                 return -EBUSY;
333
334         if (local->ops->hw_scan) {
335                 u8 *ies;
336
337                 local->hw_scan_req = kmalloc(
338                                 sizeof(*local->hw_scan_req) +
339                                 req->n_channels * sizeof(req->channels[0]) +
340                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
341                                 req->ie_len, GFP_KERNEL);
342                 if (!local->hw_scan_req)
343                         return -ENOMEM;
344
345                 local->hw_scan_req->ssids = req->ssids;
346                 local->hw_scan_req->n_ssids = req->n_ssids;
347                 ies = (u8 *)local->hw_scan_req +
348                         sizeof(*local->hw_scan_req) +
349                         req->n_channels * sizeof(req->channels[0]);
350                 local->hw_scan_req->ie = ies;
351
352                 local->hw_scan_band = 0;
353         }
354
355         local->scan_req = req;
356         local->scan_sdata = sdata;
357
358         if (!list_empty(&local->work_list)) {
359                 /* wait for the work to finish/time out */
360                 return 0;
361         }
362
363         if (local->ops->hw_scan)
364                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
365         else
366                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
367         /*
368          * Kicking off the scan need not be protected,
369          * only the scan variable stuff, since now
370          * local->scan_req is assigned and other callers
371          * will abort their scan attempts.
372          *
373          * This avoids getting a scan_mtx -> iflist_mtx
374          * dependency, so that the scan completed calls
375          * have more locking freedom.
376          */
377
378         ieee80211_recalc_idle(local);
379         mutex_unlock(&local->scan_mtx);
380
381         if (local->ops->hw_scan) {
382                 WARN_ON(!ieee80211_prep_hw_scan(local));
383                 rc = drv_hw_scan(local, local->hw_scan_req);
384         } else
385                 rc = ieee80211_start_sw_scan(local);
386
387         mutex_lock(&local->scan_mtx);
388
389         if (rc) {
390                 kfree(local->hw_scan_req);
391                 local->hw_scan_req = NULL;
392                 local->scanning = 0;
393
394                 ieee80211_recalc_idle(local);
395
396                 local->scan_req = NULL;
397                 local->scan_sdata = NULL;
398         }
399
400         return rc;
401 }
402
403 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
404                                          unsigned long *next_delay)
405 {
406         bool associated = false;
407         struct ieee80211_sub_if_data *sdata;
408
409         /* if no more bands/channels left, complete scan and advance to the idle state */
410         if (local->scan_channel_idx >= local->scan_req->n_channels) {
411                 ieee80211_scan_completed(&local->hw, false);
412                 return 1;
413         }
414
415         /* check if at least one STA interface is associated */
416         mutex_lock(&local->iflist_mtx);
417         list_for_each_entry(sdata, &local->interfaces, list) {
418                 if (!ieee80211_sdata_running(sdata))
419                         continue;
420
421                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
422                         if (sdata->u.mgd.associated) {
423                                 associated = true;
424                                 break;
425                         }
426                 }
427         }
428         mutex_unlock(&local->iflist_mtx);
429
430         if (local->scan_channel) {
431                 /*
432                  * we're currently scanning a different channel, let's
433                  * switch back to the operating channel now if at least
434                  * one interface is associated. Otherwise just scan the
435                  * next channel
436                  */
437                 if (associated)
438                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
439                 else
440                         local->next_scan_state = SCAN_SET_CHANNEL;
441         } else {
442                 /*
443                  * we're on the operating channel currently, let's
444                  * leave that channel now to scan another one
445                  */
446                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
447         }
448
449         *next_delay = 0;
450         return 0;
451 }
452
453 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
454                                                     unsigned long *next_delay)
455 {
456         ieee80211_offchannel_stop_station(local);
457
458         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
459
460         /*
461          * What if the nullfunc frames didn't arrive?
462          */
463         drv_flush(local, false);
464         if (local->ops->flush)
465                 *next_delay = 0;
466         else
467                 *next_delay = HZ / 10;
468
469         /* advance to the next channel to be scanned */
470         local->next_scan_state = SCAN_SET_CHANNEL;
471 }
472
473 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
474                                                     unsigned long *next_delay)
475 {
476         /* switch back to the operating channel */
477         local->scan_channel = NULL;
478         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
479
480         /*
481          * Only re-enable station mode interface now; beaconing will be
482          * re-enabled once the full scan has been completed.
483          */
484         ieee80211_offchannel_return(local, false);
485
486         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
487
488         *next_delay = HZ / 5;
489         local->next_scan_state = SCAN_DECISION;
490 }
491
492 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
493                                              unsigned long *next_delay)
494 {
495         int skip;
496         struct ieee80211_channel *chan;
497
498         skip = 0;
499         chan = local->scan_req->channels[local->scan_channel_idx];
500
501         local->scan_channel = chan;
502         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
503                 skip = 1;
504
505         /* advance state machine to next channel/band */
506         local->scan_channel_idx++;
507
508         if (skip) {
509                 /* if we skip this channel return to the decision state */
510                 local->next_scan_state = SCAN_DECISION;
511                 return;
512         }
513
514         /*
515          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
516          * (which unfortunately doesn't say _why_ step a) is done,
517          * but it waits for the probe delay or until a frame is
518          * received - and the received frame would update the NAV).
519          * For now, we do not support waiting until a frame is
520          * received.
521          *
522          * In any case, it is not necessary for a passive scan.
523          */
524         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
525             !local->scan_req->n_ssids) {
526                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
527                 local->next_scan_state = SCAN_DECISION;
528                 return;
529         }
530
531         /* active scan, send probes */
532         *next_delay = IEEE80211_PROBE_DELAY;
533         local->next_scan_state = SCAN_SEND_PROBE;
534 }
535
536 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
537                                             unsigned long *next_delay)
538 {
539         int i;
540         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
541
542         for (i = 0; i < local->scan_req->n_ssids; i++)
543                 ieee80211_send_probe_req(
544                         sdata, NULL,
545                         local->scan_req->ssids[i].ssid,
546                         local->scan_req->ssids[i].ssid_len,
547                         local->scan_req->ie, local->scan_req->ie_len);
548
549         /*
550          * After sending probe requests, wait for probe responses
551          * on the channel.
552          */
553         *next_delay = IEEE80211_CHANNEL_TIME;
554         local->next_scan_state = SCAN_DECISION;
555 }
556
557 void ieee80211_scan_work(struct work_struct *work)
558 {
559         struct ieee80211_local *local =
560                 container_of(work, struct ieee80211_local, scan_work.work);
561         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
562         unsigned long next_delay = 0;
563
564         mutex_lock(&local->scan_mtx);
565         if (!sdata || !local->scan_req) {
566                 mutex_unlock(&local->scan_mtx);
567                 return;
568         }
569
570         if (local->hw_scan_req) {
571                 int rc = drv_hw_scan(local, local->hw_scan_req);
572                 mutex_unlock(&local->scan_mtx);
573                 if (rc)
574                         ieee80211_scan_completed(&local->hw, true);
575                 return;
576         }
577
578         if (local->scan_req && !local->scanning) {
579                 struct cfg80211_scan_request *req = local->scan_req;
580                 int rc;
581
582                 local->scan_req = NULL;
583                 local->scan_sdata = NULL;
584
585                 rc = __ieee80211_start_scan(sdata, req);
586                 mutex_unlock(&local->scan_mtx);
587
588                 if (rc)
589                         ieee80211_scan_completed(&local->hw, true);
590                 return;
591         }
592
593         mutex_unlock(&local->scan_mtx);
594
595         /*
596          * Avoid re-scheduling when the sdata is going away.
597          */
598         if (!ieee80211_sdata_running(sdata)) {
599                 ieee80211_scan_completed(&local->hw, true);
600                 return;
601         }
602
603         /*
604          * as long as no delay is required advance immediately
605          * without scheduling a new work
606          */
607         do {
608                 switch (local->next_scan_state) {
609                 case SCAN_DECISION:
610                         if (ieee80211_scan_state_decision(local, &next_delay))
611                                 return;
612                         break;
613                 case SCAN_SET_CHANNEL:
614                         ieee80211_scan_state_set_channel(local, &next_delay);
615                         break;
616                 case SCAN_SEND_PROBE:
617                         ieee80211_scan_state_send_probe(local, &next_delay);
618                         break;
619                 case SCAN_LEAVE_OPER_CHANNEL:
620                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
621                         break;
622                 case SCAN_ENTER_OPER_CHANNEL:
623                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
624                         break;
625                 }
626         } while (next_delay == 0);
627
628         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
629 }
630
631 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
632                            struct cfg80211_scan_request *req)
633 {
634         int res;
635
636         mutex_lock(&sdata->local->scan_mtx);
637         res = __ieee80211_start_scan(sdata, req);
638         mutex_unlock(&sdata->local->scan_mtx);
639
640         return res;
641 }
642
643 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
644                                     const u8 *ssid, u8 ssid_len)
645 {
646         struct ieee80211_local *local = sdata->local;
647         int ret = -EBUSY;
648
649         mutex_lock(&local->scan_mtx);
650
651         /* busy scanning */
652         if (local->scan_req)
653                 goto unlock;
654
655         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
656         local->int_scan_req->ssids[0].ssid_len = ssid_len;
657
658         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
659  unlock:
660         mutex_unlock(&local->scan_mtx);
661         return ret;
662 }
663
664 void ieee80211_scan_cancel(struct ieee80211_local *local)
665 {
666         bool abortscan;
667
668         cancel_delayed_work_sync(&local->scan_work);
669
670         /*
671          * Only call this function when a scan can't be
672          * queued -- mostly at suspend under RTNL.
673          */
674         mutex_lock(&local->scan_mtx);
675         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
676                     (!local->scanning && local->scan_req);
677         mutex_unlock(&local->scan_mtx);
678
679         if (abortscan)
680                 ieee80211_scan_completed(&local->hw, true);
681 }