git.oblomov.eu Git - linux-2.6/blob - 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         enum cfg80211_signal_type sigtype = CFG80211_SIGNAL_TYPE_NONE;
  67         s32 signal = 0;
  68
  69         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM) {
  70                 sigtype = CFG80211_SIGNAL_TYPE_MBM;
  71                 signal = rx_status->signal * 100;
  72         } else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC) {
  73                 sigtype = CFG80211_SIGNAL_TYPE_UNSPEC;
  74                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  75         }
  76
  77         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  78                                                 mgmt, len, signal, sigtype,
  79                                                 GFP_ATOMIC);
  80
  81         if (!bss)
  82                 return NULL;
  83
  84         bss->cbss.free_priv = ieee80211_rx_bss_free;
  85
  86         /* save the ERP value so that it is available at association time */
  87         if (elems->erp_info && elems->erp_info_len >= 1) {
  88                 bss->erp_value = elems->erp_info[0];
  89                 bss->has_erp_value = 1;
  90         }
  91
  92         if (elems->tim) {
  93                 struct ieee80211_tim_ie *tim_ie =
  94                         (struct ieee80211_tim_ie *)elems->tim;
  95                 bss->dtim_period = tim_ie->dtim_period;
  96         }
  97
  98         /* set default value for buggy APs */
  99         if (!elems->tim || bss->dtim_period == 0)
 100                 bss->dtim_period = 1;
 101
 102         bss->supp_rates_len = 0;
 103         if (elems->supp_rates) {
 104                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 105                 if (clen > elems->supp_rates_len)
 106                         clen = elems->supp_rates_len;
 107                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 108                        clen);
 109                 bss->supp_rates_len += clen;
 110         }
 111         if (elems->ext_supp_rates) {
 112                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 113                 if (clen > elems->ext_supp_rates_len)
 114                         clen = elems->ext_supp_rates_len;
 115                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 116                        elems->ext_supp_rates, clen);
 117                 bss->supp_rates_len += clen;
 118         }
 119
 120         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 121
 122         if (!beacon)
 123                 bss->last_probe_resp = jiffies;
 124
 125         return bss;
 126 }
 127
 128 void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid,
 129                              int freq, u8 *ssid, u8 ssid_len)
 130 {
 131         struct ieee80211_bss *bss;
 132         struct ieee80211_local *local = sdata->local;
 133
 134         bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
 135         if (bss) {
 136                 cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
 137                 ieee80211_rx_bss_put(local, bss);
 138         }
 139 }
 140
 141 ieee80211_rx_result
 142 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
 143                   struct ieee80211_rx_status *rx_status)
 144 {
 145         struct ieee80211_mgmt *mgmt;
 146         struct ieee80211_bss *bss;
 147         u8 *elements;
 148         struct ieee80211_channel *channel;
 149         size_t baselen;
 150         int freq;
 151         __le16 fc;
 152         bool presp, beacon = false;
 153         struct ieee802_11_elems elems;
 154
 155         if (skb->len < 2)
 156                 return RX_DROP_UNUSABLE;
 157
 158         mgmt = (struct ieee80211_mgmt *) skb->data;
 159         fc = mgmt->frame_control;
 160
 161         if (ieee80211_is_ctl(fc))
 162                 return RX_CONTINUE;
 163
 164         if (skb->len < 24)
 165                 return RX_DROP_MONITOR;
 166
 167         presp = ieee80211_is_probe_resp(fc);
 168         if (presp) {
 169                 /* ignore ProbeResp to foreign address */
 170                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
 171                         return RX_DROP_MONITOR;
 172
 173                 presp = true;
 174                 elements = mgmt->u.probe_resp.variable;
 175                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 176         } else {
 177                 beacon = ieee80211_is_beacon(fc);
 178                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 179                 elements = mgmt->u.beacon.variable;
 180         }
 181
 182         if (!presp && !beacon)
 183                 return RX_CONTINUE;
 184
 185         if (baselen > skb->len)
 186                 return RX_DROP_MONITOR;
 187
 188         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 189
 190         if (elems.ds_params && elems.ds_params_len == 1)
 191                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 192         else
 193                 freq = rx_status->freq;
 194
 195         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 196
 197         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 198                 return RX_DROP_MONITOR;
 199
 200         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 201                                         mgmt, skb->len, &elems,
 202                                         channel, beacon);
 203         if (bss)
 204                 ieee80211_rx_bss_put(sdata->local, bss);
 205
 206         dev_kfree_skb(skb);
 207         return RX_QUEUED;
 208 }
 209
 210 void ieee80211_send_nullfunc(struct ieee80211_local *local,
 211                                     struct ieee80211_sub_if_data *sdata,
 212                                     int powersave)
 213 {
 214         struct sk_buff *skb;
 215         struct ieee80211_hdr *nullfunc;
 216         __le16 fc;
 217
 218         skb = dev_alloc_skb(local->hw.extra_tx_headroom + 24);
 219         if (!skb) {
 220                 printk(KERN_DEBUG "%s: failed to allocate buffer for nullfunc "
 221                        "frame\n", sdata->dev->name);
 222                 return;
 223         }
 224         skb_reserve(skb, local->hw.extra_tx_headroom);
 225
 226         nullfunc = (struct ieee80211_hdr *) skb_put(skb, 24);
 227         memset(nullfunc, 0, 24);
 228         fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_NULLFUNC |
 229                          IEEE80211_FCTL_TODS);
 230         if (powersave)
 231                 fc |= cpu_to_le16(IEEE80211_FCTL_PM);
 232         nullfunc->frame_control = fc;
 233         memcpy(nullfunc->addr1, sdata->u.sta.bssid, ETH_ALEN);
 234         memcpy(nullfunc->addr2, sdata->dev->dev_addr, ETH_ALEN);
 235         memcpy(nullfunc->addr3, sdata->u.sta.bssid, ETH_ALEN);
 236
 237         ieee80211_tx_skb(sdata, skb, 0);
 238 }
 239
 240 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 241 {
 242         struct ieee80211_local *local = hw_to_local(hw);
 243         struct ieee80211_sub_if_data *sdata;
 244
 245         if (WARN_ON(!local->hw_scanning && !local->sw_scanning))
 246                 return;
 247
 248         if (WARN_ON(!local->scan_req))
 249                 return;
 250
 251         if (local->scan_req != &local->int_scan_req)
 252                 cfg80211_scan_done(local->scan_req, aborted);
 253         local->scan_req = NULL;
 254
 255         local->last_scan_completed = jiffies;
 256
 257         if (local->hw_scanning) {
 258                 local->hw_scanning = false;
 259                 /*
 260                  * Somebody might have requested channel change during scan
 261                  * that we won't have acted upon, try now. ieee80211_hw_config
 262                  * will set the flag based on actual changes.
 263                  */
 264                 ieee80211_hw_config(local, 0);
 265                 goto done;
 266         }
 267
 268         local->sw_scanning = false;
 269         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 270
 271         netif_tx_lock_bh(local->mdev);
 272         netif_addr_lock(local->mdev);
 273         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
 274         local->ops->configure_filter(local_to_hw(local),
 275                                      FIF_BCN_PRBRESP_PROMISC,
 276                                      &local->filter_flags,
 277                                      local->mdev->mc_count,
 278                                      local->mdev->mc_list);
 279
 280         netif_addr_unlock(local->mdev);
 281         netif_tx_unlock_bh(local->mdev);
 282
 283         mutex_lock(&local->iflist_mtx);
 284         list_for_each_entry(sdata, &local->interfaces, list) {
 285                 if (!netif_running(sdata->dev))
 286                         continue;
 287
 288                 /* Tell AP we're back */
 289                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 290                         if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
 291                                 ieee80211_send_nullfunc(local, sdata, 0);
 292                                 netif_tx_wake_all_queues(sdata->dev);
 293                         }
 294                 } else
 295                         netif_tx_wake_all_queues(sdata->dev);
 296
 297                 /* re-enable beaconing */
 298                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 299                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 300                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 301                         ieee80211_if_config(sdata,
 302                                             IEEE80211_IFCC_BEACON_ENABLED);
 303         }
 304         mutex_unlock(&local->iflist_mtx);
 305
 306  done:
 307         ieee80211_mlme_notify_scan_completed(local);
 308         ieee80211_mesh_notify_scan_completed(local);
 309 }
 310 EXPORT_SYMBOL(ieee80211_scan_completed);
 311
 312 void ieee80211_scan_work(struct work_struct *work)
 313 {
 314         struct ieee80211_local *local =
 315                 container_of(work, struct ieee80211_local, scan_work.work);
 316         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 317         struct ieee80211_channel *chan;
 318         int skip, i;
 319         unsigned long next_delay = 0;
 320
 321         /*
 322          * Avoid re-scheduling when the sdata is going away.
 323          */
 324         if (!netif_running(sdata->dev))
 325                 return;
 326
 327         switch (local->scan_state) {
 328         case SCAN_SET_CHANNEL:
 329                 /* if no more bands/channels left, complete scan */
 330                 if (local->scan_channel_idx >= local->scan_req->n_channels) {
 331                         ieee80211_scan_completed(local_to_hw(local), false);
 332                         return;
 333                 }
 334                 skip = 0;
 335                 chan = local->scan_req->channels[local->scan_channel_idx];
 336
 337                 if (chan->flags & IEEE80211_CHAN_DISABLED ||
 338                     (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
 339                      chan->flags & IEEE80211_CHAN_NO_IBSS))
 340                         skip = 1;
 341
 342                 if (!skip) {
 343                         local->scan_channel = chan;
 344                         if (ieee80211_hw_config(local,
 345                                                 IEEE80211_CONF_CHANGE_CHANNEL))
 346                                 skip = 1;
 347                 }
 348
 349                 /* advance state machine to next channel/band */
 350                 local->scan_channel_idx++;
 351
 352                 if (skip)
 353                         break;
 354
 355                 next_delay = IEEE80211_PROBE_DELAY +
 356                              usecs_to_jiffies(local->hw.channel_change_time);
 357                 local->scan_state = SCAN_SEND_PROBE;
 358                 break;
 359         case SCAN_SEND_PROBE:
 360                 next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 361                 local->scan_state = SCAN_SET_CHANNEL;
 362
 363                 if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 364                     !local->scan_req->n_ssids)
 365                         break;
 366                 for (i = 0; i < local->scan_req->n_ssids; i++)
 367                         ieee80211_send_probe_req(
 368                                 sdata, NULL,
 369                                 local->scan_req->ssids[i].ssid,
 370                                 local->scan_req->ssids[i].ssid_len);
 371                 next_delay = IEEE80211_CHANNEL_TIME;
 372                 break;
 373         }
 374
 375         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 376                            next_delay);
 377 }
 378
 379
 380 int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
 381                          struct cfg80211_scan_request *req)
 382 {
 383         struct ieee80211_local *local = scan_sdata->local;
 384         struct ieee80211_sub_if_data *sdata;
 385
 386         if (!req)
 387                 return -EINVAL;
 388
 389         if (local->scan_req && local->scan_req != req)
 390                 return -EBUSY;
 391
 392         local->scan_req = req;
 393
 394         /* MLME-SCAN.request (page 118)  page 144 (11.1.3.1)
 395          * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS
 396          * BSSID: MACAddress
 397          * SSID
 398          * ScanType: ACTIVE, PASSIVE
 399          * ProbeDelay: delay (in microseconds) to be used prior to transmitting
 400          *    a Probe frame during active scanning
 401          * ChannelList
 402          * MinChannelTime (>= ProbeDelay), in TU
 403          * MaxChannelTime: (>= MinChannelTime), in TU
 404          */
 405
 406          /* MLME-SCAN.confirm
 407           * BSSDescriptionSet
 408           * ResultCode: SUCCESS, INVALID_PARAMETERS
 409          */
 410
 411         if (local->sw_scanning || local->hw_scanning) {
 412                 if (local->scan_sdata == scan_sdata)
 413                         return 0;
 414                 return -EBUSY;
 415         }
 416
 417         if (local->ops->hw_scan) {
 418                 int rc;
 419
 420                 local->hw_scanning = true;
 421                 rc = local->ops->hw_scan(local_to_hw(local), req);
 422                 if (rc) {
 423                         local->hw_scanning = false;
 424                         return rc;
 425                 }
 426                 local->scan_sdata = scan_sdata;
 427                 return 0;
 428         }
 429
 430         local->sw_scanning = true;
 431
 432         mutex_lock(&local->iflist_mtx);
 433         list_for_each_entry(sdata, &local->interfaces, list) {
 434                 if (!netif_running(sdata->dev))
 435                         continue;
 436
 437                 /* disable beaconing */
 438                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 439                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 440                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 441                         ieee80211_if_config(sdata,
 442                                             IEEE80211_IFCC_BEACON_ENABLED);
 443
 444                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 445                         if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
 446                                 netif_tx_stop_all_queues(sdata->dev);
 447                                 ieee80211_send_nullfunc(local, sdata, 1);
 448                         }
 449                 } else
 450                         netif_tx_stop_all_queues(sdata->dev);
 451         }
 452         mutex_unlock(&local->iflist_mtx);
 453
 454         local->scan_state = SCAN_SET_CHANNEL;
 455         local->scan_channel_idx = 0;
 456         local->scan_sdata = scan_sdata;
 457         local->scan_req = req;
 458
 459         netif_addr_lock_bh(local->mdev);
 460         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
 461         local->ops->configure_filter(local_to_hw(local),
 462                                      FIF_BCN_PRBRESP_PROMISC,
 463                                      &local->filter_flags,
 464                                      local->mdev->mc_count,
 465                                      local->mdev->mc_list);
 466         netif_addr_unlock_bh(local->mdev);
 467
 468         /* TODO: start scan as soon as all nullfunc frames are ACKed */
 469         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 470                            IEEE80211_CHANNEL_TIME);
 471
 472         return 0;
 473 }
 474
 475
 476 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 477                            struct cfg80211_scan_request *req)
 478 {
 479         struct ieee80211_local *local = sdata->local;
 480         struct ieee80211_if_sta *ifsta;
 481
 482         if (!req)
 483                 return -EINVAL;
 484
 485         if (local->scan_req && local->scan_req != req)
 486                 return -EBUSY;
 487
 488         local->scan_req = req;
 489
 490         if (sdata->vif.type != NL80211_IFTYPE_STATION)
 491                 return ieee80211_start_scan(sdata, req);
 492
 493         /*
 494          * STA has a state machine that might need to defer scanning
 495          * while it's trying to associate/authenticate, therefore we
 496          * queue it up to the state machine in that case.
 497          */
 498
 499         if (local->sw_scanning || local->hw_scanning) {
 500                 if (local->scan_sdata == sdata)
 501                         return 0;
 502                 return -EBUSY;
 503         }
 504
 505         ifsta = &sdata->u.sta;
 506         set_bit(IEEE80211_STA_REQ_SCAN, &ifsta->request);
 507         queue_work(local->hw.workqueue, &ifsta->work);
 508
 509         return 0;
 510 }