086d21645cbc2ab03e93f418f7b236e86db869a5
[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 /* TODO: figure out how to avoid that the "current BSS" expires */
16
17 #include <linux/wireless.h>
18 #include <linux/if_arp.h>
19 #include <linux/rtnetlink.h>
20 #include <net/mac80211.h>
21 #include <net/iw_handler.h>
22
23 #include "ieee80211_i.h"
24 #include "mesh.h"
25
26 #define IEEE80211_PROBE_DELAY (HZ / 33)
27 #define IEEE80211_CHANNEL_TIME (HZ / 33)
28 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)
29
30 struct ieee80211_bss *
31 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
32                      u8 *ssid, u8 ssid_len)
33 {
34         return (void *)cfg80211_get_bss(local->hw.wiphy,
35                                         ieee80211_get_channel(local->hw.wiphy,
36                                                               freq),
37                                         bssid, ssid, ssid_len,
38                                         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         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         cfg80211_put_bss((struct cfg80211_bss *)bss);
53 }
54
55 struct ieee80211_bss *
56 ieee80211_bss_info_update(struct ieee80211_local *local,
57                           struct ieee80211_rx_status *rx_status,
58                           struct ieee80211_mgmt *mgmt,
59                           size_t len,
60                           struct ieee802_11_elems *elems,
61                           struct ieee80211_channel *channel,
62                           bool beacon)
63 {
64         struct ieee80211_bss *bss;
65         int clen;
66         s32 signal = 0;
67
68         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
69                 signal = rx_status->signal * 100;
70         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
71                 signal = (rx_status->signal * 100) / local->hw.max_signal;
72
73         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
74                                                 mgmt, len, signal, GFP_ATOMIC);
75
76         if (!bss)
77                 return NULL;
78
79         bss->cbss.free_priv = ieee80211_rx_bss_free;
80
81         /* save the ERP value so that it is available at association time */
82         if (elems->erp_info && elems->erp_info_len >= 1) {
83                 bss->erp_value = elems->erp_info[0];
84                 bss->has_erp_value = 1;
85         }
86
87         if (elems->tim) {
88                 struct ieee80211_tim_ie *tim_ie =
89                         (struct ieee80211_tim_ie *)elems->tim;
90                 bss->dtim_period = tim_ie->dtim_period;
91         }
92
93         /* set default value for buggy APs */
94         if (!elems->tim || bss->dtim_period == 0)
95                 bss->dtim_period = 1;
96
97         bss->supp_rates_len = 0;
98         if (elems->supp_rates) {
99                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
100                 if (clen > elems->supp_rates_len)
101                         clen = elems->supp_rates_len;
102                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
103                        clen);
104                 bss->supp_rates_len += clen;
105         }
106         if (elems->ext_supp_rates) {
107                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
108                 if (clen > elems->ext_supp_rates_len)
109                         clen = elems->ext_supp_rates_len;
110                 memcpy(&bss->supp_rates[bss->supp_rates_len],
111                        elems->ext_supp_rates, clen);
112                 bss->supp_rates_len += clen;
113         }
114
115         bss->wmm_used = elems->wmm_param || elems->wmm_info;
116
117         if (!beacon)
118                 bss->last_probe_resp = jiffies;
119
120         return bss;
121 }
122
123 void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid,
124                              int freq, u8 *ssid, u8 ssid_len)
125 {
126         struct ieee80211_bss *bss;
127         struct ieee80211_local *local = sdata->local;
128
129         bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
130         if (bss) {
131                 cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
132                 ieee80211_rx_bss_put(local, bss);
133         }
134 }
135
136 ieee80211_rx_result
137 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
138                   struct ieee80211_rx_status *rx_status)
139 {
140         struct ieee80211_mgmt *mgmt;
141         struct ieee80211_bss *bss;
142         u8 *elements;
143         struct ieee80211_channel *channel;
144         size_t baselen;
145         int freq;
146         __le16 fc;
147         bool presp, beacon = false;
148         struct ieee802_11_elems elems;
149
150         if (skb->len < 2)
151                 return RX_DROP_UNUSABLE;
152
153         mgmt = (struct ieee80211_mgmt *) skb->data;
154         fc = mgmt->frame_control;
155
156         if (ieee80211_is_ctl(fc))
157                 return RX_CONTINUE;
158
159         if (skb->len < 24)
160                 return RX_DROP_MONITOR;
161
162         presp = ieee80211_is_probe_resp(fc);
163         if (presp) {
164                 /* ignore ProbeResp to foreign address */
165                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
166                         return RX_DROP_MONITOR;
167
168                 presp = true;
169                 elements = mgmt->u.probe_resp.variable;
170                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
171         } else {
172                 beacon = ieee80211_is_beacon(fc);
173                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
174                 elements = mgmt->u.beacon.variable;
175         }
176
177         if (!presp && !beacon)
178                 return RX_CONTINUE;
179
180         if (baselen > skb->len)
181                 return RX_DROP_MONITOR;
182
183         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
184
185         if (elems.ds_params && elems.ds_params_len == 1)
186                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
187         else
188                 freq = rx_status->freq;
189
190         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
191
192         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
193                 return RX_DROP_MONITOR;
194
195         bss = ieee80211_bss_info_update(sdata->local, rx_status,
196                                         mgmt, skb->len, &elems,
197                                         channel, beacon);
198         if (bss)
199                 ieee80211_rx_bss_put(sdata->local, bss);
200
201         dev_kfree_skb(skb);
202         return RX_QUEUED;
203 }
204
205 /*
206  * inform AP that we will go to sleep so that it will buffer the frames
207  * while we scan
208  */
209 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
210 {
211         struct ieee80211_local *local = sdata->local;
212         bool ps = false;
213
214         /* FIXME: what to do when local->pspolling is true? */
215
216         del_timer_sync(&local->dynamic_ps_timer);
217         cancel_work_sync(&local->dynamic_ps_enable_work);
218
219         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
220                 ps = true;
221                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
222                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
223         }
224
225         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
226                 /*
227                  * If power save was enabled, no need to send a nullfunc
228                  * frame because AP knows that we are sleeping. But if the
229                  * hardware is creating the nullfunc frame for power save
230                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
231                  * enabled) and power save was enabled, the firmware just
232                  * sent a null frame with power save disabled. So we need
233                  * to send a new nullfunc frame to inform the AP that we
234                  * are again sleeping.
235                  */
236                 ieee80211_send_nullfunc(local, sdata, 1);
237 }
238
239 /* inform AP that we are awake again, unless power save is enabled */
240 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
241 {
242         struct ieee80211_local *local = sdata->local;
243
244         if (!local->ps_sdata)
245                 ieee80211_send_nullfunc(local, sdata, 0);
246         else {
247                 /*
248                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
249                  * will send a nullfunc frame with the powersave bit set
250                  * even though the AP already knows that we are sleeping.
251                  * This could be avoided by sending a null frame with power
252                  * save bit disabled before enabling the power save, but
253                  * this doesn't gain anything.
254                  *
255                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
256                  * to send a nullfunc frame because AP already knows that
257                  * we are sleeping, let's just enable power save mode in
258                  * hardware.
259                  */
260                 local->hw.conf.flags |= IEEE80211_CONF_PS;
261                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
262         }
263 }
264
265 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
266 {
267         kfree(local->scan_req->ie);
268         local->scan_req->ie = local->orig_ies;
269         local->scan_req->ie_len = local->orig_ies_len;
270 }
271
272 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
273 {
274         struct ieee80211_local *local = hw_to_local(hw);
275         struct ieee80211_sub_if_data *sdata;
276         bool was_hw_scan;
277
278         mutex_lock(&local->scan_mtx);
279
280         if (WARN_ON(!local->hw_scanning && !local->sw_scanning)) {
281                 mutex_unlock(&local->scan_mtx);
282                 return;
283         }
284
285         if (WARN_ON(!local->scan_req)) {
286                 mutex_unlock(&local->scan_mtx);
287                 return;
288         }
289
290         if (local->hw_scanning)
291                 ieee80211_restore_scan_ies(local);
292
293         if (local->scan_req != &local->int_scan_req)
294                 cfg80211_scan_done(local->scan_req, aborted);
295         local->scan_req = NULL;
296
297         was_hw_scan = local->hw_scanning;
298         local->hw_scanning = false;
299         local->sw_scanning = false;
300
301         /* we only have to protect scan_req and hw/sw scan */
302         mutex_unlock(&local->scan_mtx);
303
304         if (was_hw_scan) {
305                 /*
306                  * Somebody might have requested channel change during scan
307                  * that we won't have acted upon, try now. ieee80211_hw_config
308                  * will set the flag based on actual changes.
309                  */
310                 ieee80211_hw_config(local, 0);
311                 goto done;
312         }
313
314         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
315
316         netif_tx_lock_bh(local->mdev);
317         netif_addr_lock(local->mdev);
318         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
319         local->ops->configure_filter(local_to_hw(local),
320                                      FIF_BCN_PRBRESP_PROMISC,
321                                      &local->filter_flags,
322                                      local->mdev->mc_count,
323                                      local->mdev->mc_list);
324
325         netif_addr_unlock(local->mdev);
326         netif_tx_unlock_bh(local->mdev);
327
328         if (local->ops->sw_scan_complete)
329                 local->ops->sw_scan_complete(local_to_hw(local));
330
331         mutex_lock(&local->iflist_mtx);
332         list_for_each_entry(sdata, &local->interfaces, list) {
333                 if (!netif_running(sdata->dev))
334                         continue;
335
336                 /* Tell AP we're back */
337                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
338                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
339                                 ieee80211_scan_ps_disable(sdata);
340                                 netif_tx_wake_all_queues(sdata->dev);
341                         }
342                 } else
343                         netif_tx_wake_all_queues(sdata->dev);
344
345                 /* re-enable beaconing */
346                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
347                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
348                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
349                         ieee80211_if_config(sdata,
350                                             IEEE80211_IFCC_BEACON_ENABLED);
351         }
352         mutex_unlock(&local->iflist_mtx);
353
354  done:
355         ieee80211_mlme_notify_scan_completed(local);
356         ieee80211_ibss_notify_scan_completed(local);
357         ieee80211_mesh_notify_scan_completed(local);
358 }
359 EXPORT_SYMBOL(ieee80211_scan_completed);
360
361 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
362 {
363         struct ieee80211_sub_if_data *sdata;
364
365         /*
366          * Hardware/driver doesn't support hw_scan, so use software
367          * scanning instead. First send a nullfunc frame with power save
368          * bit on so that AP will buffer the frames for us while we are not
369          * listening, then send probe requests to each channel and wait for
370          * the responses. After all channels are scanned, tune back to the
371          * original channel and send a nullfunc frame with power save bit
372          * off to trigger the AP to send us all the buffered frames.
373          *
374          * Note that while local->sw_scanning is true everything else but
375          * nullfunc frames and probe requests will be dropped in
376          * ieee80211_tx_h_check_assoc().
377          */
378         if (local->ops->sw_scan_start)
379                 local->ops->sw_scan_start(local_to_hw(local));
380
381         mutex_lock(&local->iflist_mtx);
382         list_for_each_entry(sdata, &local->interfaces, list) {
383                 if (!netif_running(sdata->dev))
384                         continue;
385
386                 /* disable beaconing */
387                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
388                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
389                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
390                         ieee80211_if_config(sdata,
391                                             IEEE80211_IFCC_BEACON_ENABLED);
392
393                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
394                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
395                                 netif_tx_stop_all_queues(sdata->dev);
396                                 ieee80211_scan_ps_enable(sdata);
397                         }
398                 } else
399                         netif_tx_stop_all_queues(sdata->dev);
400         }
401         mutex_unlock(&local->iflist_mtx);
402
403         local->scan_state = SCAN_SET_CHANNEL;
404         local->scan_channel_idx = 0;
405
406         netif_addr_lock_bh(local->mdev);
407         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
408         local->ops->configure_filter(local_to_hw(local),
409                                      FIF_BCN_PRBRESP_PROMISC,
410                                      &local->filter_flags,
411                                      local->mdev->mc_count,
412                                      local->mdev->mc_list);
413         netif_addr_unlock_bh(local->mdev);
414
415         /* TODO: start scan as soon as all nullfunc frames are ACKed */
416         queue_delayed_work(local->hw.workqueue, &local->scan_work,
417                            IEEE80211_CHANNEL_TIME);
418
419         return 0;
420 }
421
422
423 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
424                                   struct cfg80211_scan_request *req)
425 {
426         struct ieee80211_local *local = sdata->local;
427         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
428         int rc;
429
430         if (local->scan_req)
431                 return -EBUSY;
432
433         if (local->ops->hw_scan) {
434                 u8 *ies;
435                 int ielen;
436
437                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
438                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
439                 if (!ies)
440                         return -ENOMEM;
441
442                 ielen = ieee80211_build_preq_ies(local, ies,
443                                                  req->ie, req->ie_len);
444                 local->orig_ies = req->ie;
445                 local->orig_ies_len = req->ie_len;
446                 req->ie = ies;
447                 req->ie_len = ielen;
448         }
449
450         local->scan_req = req;
451         local->scan_sdata = sdata;
452
453         if (req != &local->int_scan_req &&
454             sdata->vif.type == NL80211_IFTYPE_STATION &&
455             (ifmgd->state == IEEE80211_STA_MLME_DIRECT_PROBE ||
456              ifmgd->state == IEEE80211_STA_MLME_AUTHENTICATE ||
457              ifmgd->state == IEEE80211_STA_MLME_ASSOCIATE)) {
458                 /* actually wait for the assoc to finish/time out */
459                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
460                 return 0;
461         }
462
463         if (local->ops->hw_scan)
464                 local->hw_scanning = true;
465         else
466                 local->sw_scanning = true;
467         /*
468          * Kicking off the scan need not be protected,
469          * only the scan variable stuff, since now
470          * local->scan_req is assigned and other callers
471          * will abort their scan attempts.
472          *
473          * This avoids getting a scan_mtx -> iflist_mtx
474          * dependency, so that the scan completed calls
475          * have more locking freedom.
476          */
477         mutex_unlock(&local->scan_mtx);
478
479         if (local->ops->hw_scan)
480                 rc = local->ops->hw_scan(local_to_hw(local),
481                                          local->scan_req);
482         else
483                 rc = ieee80211_start_sw_scan(local);
484
485         mutex_lock(&local->scan_mtx);
486
487         if (rc) {
488                 if (local->ops->hw_scan) {
489                         local->hw_scanning = false;
490                         ieee80211_restore_scan_ies(local);
491                 } else
492                         local->sw_scanning = false;
493
494                 local->scan_req = NULL;
495                 local->scan_sdata = NULL;
496         }
497
498         return rc;
499 }
500
501 void ieee80211_scan_work(struct work_struct *work)
502 {
503         struct ieee80211_local *local =
504                 container_of(work, struct ieee80211_local, scan_work.work);
505         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
506         struct ieee80211_channel *chan;
507         int skip, i;
508         unsigned long next_delay = 0;
509
510         mutex_lock(&local->scan_mtx);
511         if (!sdata || !local->scan_req) {
512                 mutex_unlock(&local->scan_mtx);
513                 return;
514         }
515
516         if (local->scan_req && !(local->sw_scanning || local->hw_scanning)) {
517                 struct cfg80211_scan_request *req = local->scan_req;
518                 int rc;
519
520                 local->scan_req = NULL;
521
522                 rc = __ieee80211_start_scan(sdata, req);
523                 mutex_unlock(&local->scan_mtx);
524
525                 if (rc)
526                         ieee80211_scan_completed(&local->hw, true);
527                 return;
528         }
529
530         mutex_unlock(&local->scan_mtx);
531
532         /*
533          * Avoid re-scheduling when the sdata is going away.
534          */
535         if (!netif_running(sdata->dev)) {
536                 ieee80211_scan_completed(&local->hw, true);
537                 return;
538         }
539
540         switch (local->scan_state) {
541         case SCAN_SET_CHANNEL:
542                 /* if no more bands/channels left, complete scan */
543                 if (local->scan_channel_idx >= local->scan_req->n_channels) {
544                         ieee80211_scan_completed(&local->hw, false);
545                         return;
546                 }
547                 skip = 0;
548                 chan = local->scan_req->channels[local->scan_channel_idx];
549
550                 if (chan->flags & IEEE80211_CHAN_DISABLED ||
551                     (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
552                      chan->flags & IEEE80211_CHAN_NO_IBSS))
553                         skip = 1;
554
555                 if (!skip) {
556                         local->scan_channel = chan;
557                         if (ieee80211_hw_config(local,
558                                                 IEEE80211_CONF_CHANGE_CHANNEL))
559                                 skip = 1;
560                 }
561
562                 /* advance state machine to next channel/band */
563                 local->scan_channel_idx++;
564
565                 if (skip)
566                         break;
567
568                 next_delay = IEEE80211_PROBE_DELAY +
569                              usecs_to_jiffies(local->hw.channel_change_time);
570                 local->scan_state = SCAN_SEND_PROBE;
571                 break;
572         case SCAN_SEND_PROBE:
573                 next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
574                 local->scan_state = SCAN_SET_CHANNEL;
575
576                 if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
577                     !local->scan_req->n_ssids)
578                         break;
579                 for (i = 0; i < local->scan_req->n_ssids; i++)
580                         ieee80211_send_probe_req(
581                                 sdata, NULL,
582                                 local->scan_req->ssids[i].ssid,
583                                 local->scan_req->ssids[i].ssid_len,
584                                 local->scan_req->ie, local->scan_req->ie_len);
585                 next_delay = IEEE80211_CHANNEL_TIME;
586                 break;
587         }
588
589         queue_delayed_work(local->hw.workqueue, &local->scan_work,
590                            next_delay);
591 }
592
593 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
594                            struct cfg80211_scan_request *req)
595 {
596         int res;
597
598         mutex_lock(&sdata->local->scan_mtx);
599         res = __ieee80211_start_scan(sdata, req);
600         mutex_unlock(&sdata->local->scan_mtx);
601
602         return res;
603 }
604
605 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
606                                     const u8 *ssid, u8 ssid_len)
607 {
608         struct ieee80211_local *local = sdata->local;
609         int ret = -EBUSY;
610
611         mutex_lock(&local->scan_mtx);
612
613         /* busy scanning */
614         if (local->scan_req)
615                 goto unlock;
616
617         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
618         local->int_scan_req.ssids[0].ssid_len = ssid_len;
619
620         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
621  unlock:
622         mutex_unlock(&local->scan_mtx);
623         return ret;
624 }