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