48f910ae95c0c2d79f0c9ba671d8d8d5327fdd8b
[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 "driver-ops.h"
25 #include "mesh.h"
26
27 #define IEEE80211_PROBE_DELAY (HZ / 33)
28 #define IEEE80211_CHANNEL_TIME (HZ / 33)
29 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
30
31 struct ieee80211_bss *
32 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
33                      u8 *ssid, u8 ssid_len)
34 {
35         return (void *)cfg80211_get_bss(local->hw.wiphy,
36                                         ieee80211_get_channel(local->hw.wiphy,
37                                                               freq),
38                                         bssid, ssid, ssid_len,
39                                         0, 0);
40 }
41
42 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
43 {
44         struct ieee80211_bss *bss = (void *)cbss;
45
46         kfree(bss_mesh_id(bss));
47         kfree(bss_mesh_cfg(bss));
48 }
49
50 void ieee80211_rx_bss_put(struct ieee80211_local *local,
51                           struct ieee80211_bss *bss)
52 {
53         cfg80211_put_bss((struct cfg80211_bss *)bss);
54 }
55
56 struct ieee80211_bss *
57 ieee80211_bss_info_update(struct ieee80211_local *local,
58                           struct ieee80211_rx_status *rx_status,
59                           struct ieee80211_mgmt *mgmt,
60                           size_t len,
61                           struct ieee802_11_elems *elems,
62                           struct ieee80211_channel *channel,
63                           bool beacon)
64 {
65         struct ieee80211_bss *bss;
66         int clen;
67         s32 signal = 0;
68
69         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
70                 signal = rx_status->signal * 100;
71         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
72                 signal = (rx_status->signal * 100) / local->hw.max_signal;
73
74         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
75                                                 mgmt, len, signal, GFP_ATOMIC);
76
77         if (!bss)
78                 return NULL;
79
80         bss->cbss.free_priv = ieee80211_rx_bss_free;
81
82         /* save the ERP value so that it is available at association time */
83         if (elems->erp_info && elems->erp_info_len >= 1) {
84                 bss->erp_value = elems->erp_info[0];
85                 bss->has_erp_value = 1;
86         }
87
88         if (elems->tim) {
89                 struct ieee80211_tim_ie *tim_ie =
90                         (struct ieee80211_tim_ie *)elems->tim;
91                 bss->dtim_period = tim_ie->dtim_period;
92         }
93
94         /* set default value for buggy APs */
95         if (!elems->tim || bss->dtim_period == 0)
96                 bss->dtim_period = 1;
97
98         bss->supp_rates_len = 0;
99         if (elems->supp_rates) {
100                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
101                 if (clen > elems->supp_rates_len)
102                         clen = elems->supp_rates_len;
103                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
104                        clen);
105                 bss->supp_rates_len += clen;
106         }
107         if (elems->ext_supp_rates) {
108                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
109                 if (clen > elems->ext_supp_rates_len)
110                         clen = elems->ext_supp_rates_len;
111                 memcpy(&bss->supp_rates[bss->supp_rates_len],
112                        elems->ext_supp_rates, clen);
113                 bss->supp_rates_len += clen;
114         }
115
116         bss->wmm_used = elems->wmm_param || elems->wmm_info;
117
118         if (!beacon)
119                 bss->last_probe_resp = jiffies;
120
121         return bss;
122 }
123
124 ieee80211_rx_result
125 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
126 {
127         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
128         struct ieee80211_mgmt *mgmt;
129         struct ieee80211_bss *bss;
130         u8 *elements;
131         struct ieee80211_channel *channel;
132         size_t baselen;
133         int freq;
134         __le16 fc;
135         bool presp, beacon = false;
136         struct ieee802_11_elems elems;
137
138         if (skb->len < 2)
139                 return RX_DROP_UNUSABLE;
140
141         mgmt = (struct ieee80211_mgmt *) skb->data;
142         fc = mgmt->frame_control;
143
144         if (ieee80211_is_ctl(fc))
145                 return RX_CONTINUE;
146
147         if (skb->len < 24)
148                 return RX_DROP_MONITOR;
149
150         presp = ieee80211_is_probe_resp(fc);
151         if (presp) {
152                 /* ignore ProbeResp to foreign address */
153                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
154                         return RX_DROP_MONITOR;
155
156                 presp = true;
157                 elements = mgmt->u.probe_resp.variable;
158                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
159         } else {
160                 beacon = ieee80211_is_beacon(fc);
161                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
162                 elements = mgmt->u.beacon.variable;
163         }
164
165         if (!presp && !beacon)
166                 return RX_CONTINUE;
167
168         if (baselen > skb->len)
169                 return RX_DROP_MONITOR;
170
171         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
172
173         if (elems.ds_params && elems.ds_params_len == 1)
174                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
175         else
176                 freq = rx_status->freq;
177
178         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
179
180         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
181                 return RX_DROP_MONITOR;
182
183         bss = ieee80211_bss_info_update(sdata->local, rx_status,
184                                         mgmt, skb->len, &elems,
185                                         channel, beacon);
186         if (bss)
187                 ieee80211_rx_bss_put(sdata->local, bss);
188
189         dev_kfree_skb(skb);
190         return RX_QUEUED;
191 }
192
193 /*
194  * inform AP that we will go to sleep so that it will buffer the frames
195  * while we scan
196  */
197 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
198 {
199         struct ieee80211_local *local = sdata->local;
200         bool ps = false;
201
202         /* FIXME: what to do when local->pspolling is true? */
203
204         del_timer_sync(&local->dynamic_ps_timer);
205         cancel_work_sync(&local->dynamic_ps_enable_work);
206
207         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
208                 ps = true;
209                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
210                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
211         }
212
213         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
214                 /*
215                  * If power save was enabled, no need to send a nullfunc
216                  * frame because AP knows that we are sleeping. But if the
217                  * hardware is creating the nullfunc frame for power save
218                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
219                  * enabled) and power save was enabled, the firmware just
220                  * sent a null frame with power save disabled. So we need
221                  * to send a new nullfunc frame to inform the AP that we
222                  * are again sleeping.
223                  */
224                 ieee80211_send_nullfunc(local, sdata, 1);
225 }
226
227 /* inform AP that we are awake again, unless power save is enabled */
228 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
229 {
230         struct ieee80211_local *local = sdata->local;
231
232         if (!local->ps_sdata)
233                 ieee80211_send_nullfunc(local, sdata, 0);
234         else {
235                 /*
236                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
237                  * will send a nullfunc frame with the powersave bit set
238                  * even though the AP already knows that we are sleeping.
239                  * This could be avoided by sending a null frame with power
240                  * save bit disabled before enabling the power save, but
241                  * this doesn't gain anything.
242                  *
243                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
244                  * to send a nullfunc frame because AP already knows that
245                  * we are sleeping, let's just enable power save mode in
246                  * hardware.
247                  */
248                 local->hw.conf.flags |= IEEE80211_CONF_PS;
249                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
250         }
251 }
252
253 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
254 {
255         kfree(local->scan_req->ie);
256         local->scan_req->ie = local->orig_ies;
257         local->scan_req->ie_len = local->orig_ies_len;
258 }
259
260 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
261 {
262         struct ieee80211_local *local = hw_to_local(hw);
263         struct ieee80211_sub_if_data *sdata;
264         bool was_hw_scan;
265
266         mutex_lock(&local->scan_mtx);
267
268         if (WARN_ON(!local->hw_scanning && !local->sw_scanning)) {
269                 mutex_unlock(&local->scan_mtx);
270                 return;
271         }
272
273         if (WARN_ON(!local->scan_req)) {
274                 mutex_unlock(&local->scan_mtx);
275                 return;
276         }
277
278         if (local->hw_scanning)
279                 ieee80211_restore_scan_ies(local);
280
281         if (local->scan_req != &local->int_scan_req)
282                 cfg80211_scan_done(local->scan_req, aborted);
283         local->scan_req = NULL;
284
285         was_hw_scan = local->hw_scanning;
286         local->hw_scanning = false;
287         local->sw_scanning = false;
288         local->scan_channel = NULL;
289
290         /* we only have to protect scan_req and hw/sw scan */
291         mutex_unlock(&local->scan_mtx);
292
293         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
294         if (was_hw_scan)
295                 goto done;
296
297         spin_lock_bh(&local->filter_lock);
298         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
299         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
300                              &local->filter_flags,
301                              local->mc_count,
302                              local->mc_list);
303         spin_unlock_bh(&local->filter_lock);
304
305         drv_sw_scan_complete(local);
306
307         mutex_lock(&local->iflist_mtx);
308         list_for_each_entry(sdata, &local->interfaces, list) {
309                 if (!netif_running(sdata->dev))
310                         continue;
311
312                 /* Tell AP we're back */
313                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
314                         if (sdata->u.mgd.associated) {
315                                 ieee80211_scan_ps_disable(sdata);
316                                 netif_tx_wake_all_queues(sdata->dev);
317                         }
318                 } else
319                         netif_tx_wake_all_queues(sdata->dev);
320
321                 /* re-enable beaconing */
322                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
323                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
324                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
325                         ieee80211_bss_info_change_notify(
326                                 sdata, BSS_CHANGED_BEACON_ENABLED);
327         }
328         mutex_unlock(&local->iflist_mtx);
329
330  done:
331         ieee80211_recalc_idle(local);
332         ieee80211_mlme_notify_scan_completed(local);
333         ieee80211_ibss_notify_scan_completed(local);
334         ieee80211_mesh_notify_scan_completed(local);
335 }
336 EXPORT_SYMBOL(ieee80211_scan_completed);
337
338 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
339 {
340         struct ieee80211_sub_if_data *sdata;
341
342         /*
343          * Hardware/driver doesn't support hw_scan, so use software
344          * scanning instead. First send a nullfunc frame with power save
345          * bit on so that AP will buffer the frames for us while we are not
346          * listening, then send probe requests to each channel and wait for
347          * the responses. After all channels are scanned, tune back to the
348          * original channel and send a nullfunc frame with power save bit
349          * off to trigger the AP to send us all the buffered frames.
350          *
351          * Note that while local->sw_scanning is true everything else but
352          * nullfunc frames and probe requests will be dropped in
353          * ieee80211_tx_h_check_assoc().
354          */
355         drv_sw_scan_start(local);
356
357         mutex_lock(&local->iflist_mtx);
358         list_for_each_entry(sdata, &local->interfaces, list) {
359                 if (!netif_running(sdata->dev))
360                         continue;
361
362                 /* disable beaconing */
363                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
364                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
365                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
366                         ieee80211_bss_info_change_notify(
367                                 sdata, BSS_CHANGED_BEACON_ENABLED);
368
369                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
370                         if (sdata->u.mgd.associated) {
371                                 netif_tx_stop_all_queues(sdata->dev);
372                                 ieee80211_scan_ps_enable(sdata);
373                         }
374                 } else
375                         netif_tx_stop_all_queues(sdata->dev);
376         }
377         mutex_unlock(&local->iflist_mtx);
378
379         local->scan_state = SCAN_DECISION;
380         local->scan_channel_idx = 0;
381
382         spin_lock_bh(&local->filter_lock);
383         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
384         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
385                              &local->filter_flags,
386                              local->mc_count,
387                              local->mc_list);
388         spin_unlock_bh(&local->filter_lock);
389
390         /* TODO: start scan as soon as all nullfunc frames are ACKed */
391         queue_delayed_work(local->hw.workqueue, &local->scan_work,
392                            IEEE80211_CHANNEL_TIME);
393
394         return 0;
395 }
396
397
398 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
399                                   struct cfg80211_scan_request *req)
400 {
401         struct ieee80211_local *local = sdata->local;
402         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
403         int rc;
404
405         if (local->scan_req)
406                 return -EBUSY;
407
408         if (local->ops->hw_scan) {
409                 u8 *ies;
410                 int ielen;
411
412                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
413                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
414                 if (!ies)
415                         return -ENOMEM;
416
417                 ielen = ieee80211_build_preq_ies(local, ies,
418                                                  req->ie, req->ie_len);
419                 local->orig_ies = req->ie;
420                 local->orig_ies_len = req->ie_len;
421                 req->ie = ies;
422                 req->ie_len = ielen;
423         }
424
425         local->scan_req = req;
426         local->scan_sdata = sdata;
427
428         if (req != &local->int_scan_req &&
429             sdata->vif.type == NL80211_IFTYPE_STATION &&
430             !list_empty(&ifmgd->work_list)) {
431                 /* actually wait for the work it's doing to finish/time out */
432                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
433                 return 0;
434         }
435
436         if (local->ops->hw_scan)
437                 local->hw_scanning = true;
438         else
439                 local->sw_scanning = true;
440         /*
441          * Kicking off the scan need not be protected,
442          * only the scan variable stuff, since now
443          * local->scan_req is assigned and other callers
444          * will abort their scan attempts.
445          *
446          * This avoids getting a scan_mtx -> iflist_mtx
447          * dependency, so that the scan completed calls
448          * have more locking freedom.
449          */
450
451         ieee80211_recalc_idle(local);
452         mutex_unlock(&local->scan_mtx);
453
454         if (local->ops->hw_scan)
455                 rc = drv_hw_scan(local, local->scan_req);
456         else
457                 rc = ieee80211_start_sw_scan(local);
458
459         mutex_lock(&local->scan_mtx);
460
461         if (rc) {
462                 if (local->ops->hw_scan) {
463                         local->hw_scanning = false;
464                         ieee80211_restore_scan_ies(local);
465                 } else
466                         local->sw_scanning = false;
467
468                 ieee80211_recalc_idle(local);
469
470                 local->scan_req = NULL;
471                 local->scan_sdata = NULL;
472         }
473
474         return rc;
475 }
476
477 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
478                                          unsigned long *next_delay)
479 {
480         /* if no more bands/channels left, complete scan */
481         if (local->scan_channel_idx >= local->scan_req->n_channels) {
482                 ieee80211_scan_completed(&local->hw, false);
483                 return 1;
484         }
485
486         *next_delay = 0;
487         local->scan_state = SCAN_SET_CHANNEL;
488         return 0;
489 }
490
491 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
492                                              unsigned long *next_delay)
493 {
494         int skip;
495         struct ieee80211_channel *chan;
496         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
497
498         skip = 0;
499         chan = local->scan_req->channels[local->scan_channel_idx];
500
501         if (chan->flags & IEEE80211_CHAN_DISABLED ||
502             (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
503              chan->flags & IEEE80211_CHAN_NO_IBSS))
504                 skip = 1;
505
506         if (!skip) {
507                 local->scan_channel = chan;
508                 if (ieee80211_hw_config(local,
509                                         IEEE80211_CONF_CHANGE_CHANNEL))
510                         skip = 1;
511         }
512
513         /* advance state machine to next channel/band */
514         local->scan_channel_idx++;
515
516         if (skip)
517                 return;
518
519         /*
520          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
521          * (which unfortunately doesn't say _why_ step a) is done,
522          * but it waits for the probe delay or until a frame is
523          * received - and the received frame would update the NAV).
524          * For now, we do not support waiting until a frame is
525          * received.
526          *
527          * In any case, it is not necessary for a passive scan.
528          */
529         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
530             !local->scan_req->n_ssids) {
531                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
532                 local->scan_state = SCAN_DECISION;
533                 return;
534         }
535
536         /* active scan, send probes */
537         *next_delay = IEEE80211_PROBE_DELAY;
538         local->scan_state = SCAN_SEND_PROBE;
539 }
540
541 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
542                                             unsigned long *next_delay)
543 {
544         int i;
545         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
546
547         for (i = 0; i < local->scan_req->n_ssids; i++)
548                 ieee80211_send_probe_req(
549                         sdata, NULL,
550                         local->scan_req->ssids[i].ssid,
551                         local->scan_req->ssids[i].ssid_len,
552                         local->scan_req->ie, local->scan_req->ie_len);
553
554         /*
555          * After sending probe requests, wait for probe responses
556          * on the channel.
557          */
558         *next_delay = IEEE80211_CHANNEL_TIME;
559         local->scan_state = SCAN_DECISION;
560 }
561
562 void ieee80211_scan_work(struct work_struct *work)
563 {
564         struct ieee80211_local *local =
565                 container_of(work, struct ieee80211_local, scan_work.work);
566         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
567         unsigned long next_delay = 0;
568
569         mutex_lock(&local->scan_mtx);
570         if (!sdata || !local->scan_req) {
571                 mutex_unlock(&local->scan_mtx);
572                 return;
573         }
574
575         if (local->scan_req && !(local->sw_scanning || local->hw_scanning)) {
576                 struct cfg80211_scan_request *req = local->scan_req;
577                 int rc;
578
579                 local->scan_req = NULL;
580
581                 rc = __ieee80211_start_scan(sdata, req);
582                 mutex_unlock(&local->scan_mtx);
583
584                 if (rc)
585                         ieee80211_scan_completed(&local->hw, true);
586                 return;
587         }
588
589         mutex_unlock(&local->scan_mtx);
590
591         /*
592          * Avoid re-scheduling when the sdata is going away.
593          */
594         if (!netif_running(sdata->dev)) {
595                 ieee80211_scan_completed(&local->hw, true);
596                 return;
597         }
598
599         /*
600          * as long as no delay is required advance immediately
601          * without scheduling a new work
602          */
603         do {
604                 switch (local->scan_state) {
605                 case SCAN_DECISION:
606                         if (ieee80211_scan_state_decision(local, &next_delay))
607                                 return;
608                         break;
609                 case SCAN_SET_CHANNEL:
610                         ieee80211_scan_state_set_channel(local, &next_delay);
611                         break;
612                 case SCAN_SEND_PROBE:
613                         ieee80211_scan_state_send_probe(local, &next_delay);
614                         break;
615                 }
616         } while (next_delay == 0);
617
618         queue_delayed_work(local->hw.workqueue, &local->scan_work,
619                            next_delay);
620 }
621
622 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
623                            struct cfg80211_scan_request *req)
624 {
625         int res;
626
627         mutex_lock(&sdata->local->scan_mtx);
628         res = __ieee80211_start_scan(sdata, req);
629         mutex_unlock(&sdata->local->scan_mtx);
630
631         return res;
632 }
633
634 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
635                                     const u8 *ssid, u8 ssid_len)
636 {
637         struct ieee80211_local *local = sdata->local;
638         int ret = -EBUSY;
639
640         mutex_lock(&local->scan_mtx);
641
642         /* busy scanning */
643         if (local->scan_req)
644                 goto unlock;
645
646         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
647         local->int_scan_req.ssids[0].ssid_len = ssid_len;
648
649         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
650  unlock:
651         mutex_unlock(&local->scan_mtx);
652         return ret;
653 }
654
655 void ieee80211_scan_cancel(struct ieee80211_local *local)
656 {
657         bool swscan;
658
659         cancel_delayed_work_sync(&local->scan_work);
660
661         /*
662          * Only call this function when a scan can't be
663          * queued -- mostly at suspend under RTNL.
664          */
665         mutex_lock(&local->scan_mtx);
666         swscan = local->sw_scanning;
667         mutex_unlock(&local->scan_mtx);
668
669         if (swscan)
670                 ieee80211_scan_completed(&local->hw, true);
671 }