include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit...
[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 <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
28 struct ieee80211_bss *
29 ieee80211_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
42 static 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
50 void 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
58 static 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
75 struct ieee80211_bss *
76 ieee80211_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
142 ieee80211_rx_result
143 ieee80211_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 */
212 static 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
244 void 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 }
304 EXPORT_SYMBOL(ieee80211_scan_completed);
305
306 static 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
340 static 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
429 static 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
479 static 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
499 static 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
518 static 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
562 static 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
583 void 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
657 int 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
669 int 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
690 void 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 }