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 void ieee80211_scan_failed(struct ieee80211_local *local)
 206 {
 207         if (WARN_ON(!local->scan_req))
 208                 return;
 209
 210         /* notify cfg80211 about the failed scan */
 211         if (local->scan_req != &local->int_scan_req)
 212                 cfg80211_scan_done(local->scan_req, true);
 213
 214         local->scan_req = NULL;
 215 }
 216
 217 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 218 {
 219         struct ieee80211_local *local = hw_to_local(hw);
 220         struct ieee80211_sub_if_data *sdata;
 221
 222         if (WARN_ON(!local->hw_scanning && !local->sw_scanning))
 223                 return;
 224
 225         if (WARN_ON(!local->scan_req))
 226                 return;
 227
 228         if (local->scan_req != &local->int_scan_req)
 229                 cfg80211_scan_done(local->scan_req, aborted);
 230         local->scan_req = NULL;
 231
 232         local->last_scan_completed = jiffies;
 233
 234         if (local->hw_scanning) {
 235                 local->hw_scanning = false;
 236                 /*
 237                  * Somebody might have requested channel change during scan
 238                  * that we won't have acted upon, try now. ieee80211_hw_config
 239                  * will set the flag based on actual changes.
 240                  */
 241                 ieee80211_hw_config(local, 0);
 242                 goto done;
 243         }
 244
 245         local->sw_scanning = false;
 246         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 247
 248         netif_tx_lock_bh(local->mdev);
 249         netif_addr_lock(local->mdev);
 250         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
 251         local->ops->configure_filter(local_to_hw(local),
 252                                      FIF_BCN_PRBRESP_PROMISC,
 253                                      &local->filter_flags,
 254                                      local->mdev->mc_count,
 255                                      local->mdev->mc_list);
 256
 257         netif_addr_unlock(local->mdev);
 258         netif_tx_unlock_bh(local->mdev);
 259
 260         if (local->ops->sw_scan_complete)
 261                 local->ops->sw_scan_complete(local_to_hw(local));
 262
 263         mutex_lock(&local->iflist_mtx);
 264         list_for_each_entry(sdata, &local->interfaces, list) {
 265                 if (!netif_running(sdata->dev))
 266                         continue;
 267
 268                 /* Tell AP we're back */
 269                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 270                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
 271                                 ieee80211_send_nullfunc(local, sdata, 0);
 272                                 netif_tx_wake_all_queues(sdata->dev);
 273                         }
 274                 } else
 275                         netif_tx_wake_all_queues(sdata->dev);
 276
 277                 /* re-enable beaconing */
 278                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 279                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 280                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 281                         ieee80211_if_config(sdata,
 282                                             IEEE80211_IFCC_BEACON_ENABLED);
 283         }
 284         mutex_unlock(&local->iflist_mtx);
 285
 286  done:
 287         ieee80211_mlme_notify_scan_completed(local);
 288         ieee80211_ibss_notify_scan_completed(local);
 289         ieee80211_mesh_notify_scan_completed(local);
 290 }
 291 EXPORT_SYMBOL(ieee80211_scan_completed);
 292
 293 void ieee80211_scan_work(struct work_struct *work)
 294 {
 295         struct ieee80211_local *local =
 296                 container_of(work, struct ieee80211_local, scan_work.work);
 297         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 298         struct ieee80211_channel *chan;
 299         int skip, i;
 300         unsigned long next_delay = 0;
 301
 302         /*
 303          * Avoid re-scheduling when the sdata is going away.
 304          */
 305         if (!netif_running(sdata->dev))
 306                 return;
 307
 308         switch (local->scan_state) {
 309         case SCAN_SET_CHANNEL:
 310                 /* if no more bands/channels left, complete scan */
 311                 if (local->scan_channel_idx >= local->scan_req->n_channels) {
 312                         ieee80211_scan_completed(local_to_hw(local), false);
 313                         return;
 314                 }
 315                 skip = 0;
 316                 chan = local->scan_req->channels[local->scan_channel_idx];
 317
 318                 if (chan->flags & IEEE80211_CHAN_DISABLED ||
 319                     (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
 320                      chan->flags & IEEE80211_CHAN_NO_IBSS))
 321                         skip = 1;
 322
 323                 if (!skip) {
 324                         local->scan_channel = chan;
 325                         if (ieee80211_hw_config(local,
 326                                                 IEEE80211_CONF_CHANGE_CHANNEL))
 327                                 skip = 1;
 328                 }
 329
 330                 /* advance state machine to next channel/band */
 331                 local->scan_channel_idx++;
 332
 333                 if (skip)
 334                         break;
 335
 336                 next_delay = IEEE80211_PROBE_DELAY +
 337                              usecs_to_jiffies(local->hw.channel_change_time);
 338                 local->scan_state = SCAN_SEND_PROBE;
 339                 break;
 340         case SCAN_SEND_PROBE:
 341                 next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 342                 local->scan_state = SCAN_SET_CHANNEL;
 343
 344                 if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 345                     !local->scan_req->n_ssids)
 346                         break;
 347                 for (i = 0; i < local->scan_req->n_ssids; i++)
 348                         ieee80211_send_probe_req(
 349                                 sdata, NULL,
 350                                 local->scan_req->ssids[i].ssid,
 351                                 local->scan_req->ssids[i].ssid_len,
 352                                 local->scan_req->ie, local->scan_req->ie_len);
 353                 next_delay = IEEE80211_CHANNEL_TIME;
 354                 break;
 355         }
 356
 357         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 358                            next_delay);
 359 }
 360
 361
 362 int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
 363                          struct cfg80211_scan_request *req)
 364 {
 365         struct ieee80211_local *local = scan_sdata->local;
 366         struct ieee80211_sub_if_data *sdata;
 367
 368         if (!req)
 369                 return -EINVAL;
 370
 371         if (local->scan_req && local->scan_req != req)
 372                 return -EBUSY;
 373
 374         local->scan_req = req;
 375
 376         /* MLME-SCAN.request (page 118)  page 144 (11.1.3.1)
 377          * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS
 378          * BSSID: MACAddress
 379          * SSID
 380          * ScanType: ACTIVE, PASSIVE
 381          * ProbeDelay: delay (in microseconds) to be used prior to transmitting
 382          *    a Probe frame during active scanning
 383          * ChannelList
 384          * MinChannelTime (>= ProbeDelay), in TU
 385          * MaxChannelTime: (>= MinChannelTime), in TU
 386          */
 387
 388          /* MLME-SCAN.confirm
 389           * BSSDescriptionSet
 390           * ResultCode: SUCCESS, INVALID_PARAMETERS
 391          */
 392
 393         if (local->sw_scanning || local->hw_scanning) {
 394                 if (local->scan_sdata == scan_sdata)
 395                         return 0;
 396                 return -EBUSY;
 397         }
 398
 399         if (local->ops->hw_scan) {
 400                 int rc;
 401
 402                 local->hw_scanning = true;
 403                 rc = local->ops->hw_scan(local_to_hw(local), req);
 404                 if (rc) {
 405                         local->hw_scanning = false;
 406                         return rc;
 407                 }
 408                 local->scan_sdata = scan_sdata;
 409                 return 0;
 410         }
 411
 412         /*
 413          * Hardware/driver doesn't support hw_scan, so use software
 414          * scanning instead. First send a nullfunc frame with power save
 415          * bit on so that AP will buffer the frames for us while we are not
 416          * listening, then send probe requests to each channel and wait for
 417          * the responses. After all channels are scanned, tune back to the
 418          * original channel and send a nullfunc frame with power save bit
 419          * off to trigger the AP to send us all the buffered frames.
 420          *
 421          * Note that while local->sw_scanning is true everything else but
 422          * nullfunc frames and probe requests will be dropped in
 423          * ieee80211_tx_h_check_assoc().
 424          */
 425         local->sw_scanning = true;
 426         if (local->ops->sw_scan_start)
 427                 local->ops->sw_scan_start(local_to_hw(local));
 428
 429         mutex_lock(&local->iflist_mtx);
 430         list_for_each_entry(sdata, &local->interfaces, list) {
 431                 if (!netif_running(sdata->dev))
 432                         continue;
 433
 434                 /* disable beaconing */
 435                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 436                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 437                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 438                         ieee80211_if_config(sdata,
 439                                             IEEE80211_IFCC_BEACON_ENABLED);
 440
 441                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 442                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
 443                                 netif_tx_stop_all_queues(sdata->dev);
 444                                 ieee80211_send_nullfunc(local, sdata, 1);
 445                         }
 446                 } else
 447                         netif_tx_stop_all_queues(sdata->dev);
 448         }
 449         mutex_unlock(&local->iflist_mtx);
 450
 451         local->scan_state = SCAN_SET_CHANNEL;
 452         local->scan_channel_idx = 0;
 453         local->scan_sdata = scan_sdata;
 454         local->scan_req = req;
 455
 456         netif_addr_lock_bh(local->mdev);
 457         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
 458         local->ops->configure_filter(local_to_hw(local),
 459                                      FIF_BCN_PRBRESP_PROMISC,
 460                                      &local->filter_flags,
 461                                      local->mdev->mc_count,
 462                                      local->mdev->mc_list);
 463         netif_addr_unlock_bh(local->mdev);
 464
 465         /* TODO: start scan as soon as all nullfunc frames are ACKed */
 466         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 467                            IEEE80211_CHANNEL_TIME);
 468
 469         return 0;
 470 }
 471
 472
 473 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 474                            struct cfg80211_scan_request *req)
 475 {
 476         struct ieee80211_local *local = sdata->local;
 477         struct ieee80211_if_managed *ifmgd;
 478
 479         if (!req)
 480                 return -EINVAL;
 481
 482         if (local->scan_req && local->scan_req != req)
 483                 return -EBUSY;
 484
 485         local->scan_req = req;
 486
 487         if (sdata->vif.type != NL80211_IFTYPE_STATION)
 488                 return ieee80211_start_scan(sdata, req);
 489
 490         /*
 491          * STA has a state machine that might need to defer scanning
 492          * while it's trying to associate/authenticate, therefore we
 493          * queue it up to the state machine in that case.
 494          */
 495
 496         if (local->sw_scanning || local->hw_scanning) {
 497                 if (local->scan_sdata == sdata)
 498                         return 0;
 499                 return -EBUSY;
 500         }
 501
 502         ifmgd = &sdata->u.mgd;
 503         set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
 504         queue_work(local->hw.workqueue, &ifmgd->work);
 505
 506         return 0;
 507 }