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 /* 218 * inform AP that we will go to sleep so that it will buffer the frames 219 * while we scan 220 */ 221 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata) 222 { 223 struct ieee80211_local *local = sdata->local; 224 bool ps = false; 225 226 /* FIXME: what to do when local->pspolling is true? */ 227 228 del_timer_sync(&local->dynamic_ps_timer); 229 cancel_work_sync(&local->dynamic_ps_enable_work); 230 231 if (local->hw.conf.flags & IEEE80211_CONF_PS) { 232 ps = true; 233 local->hw.conf.flags &= ~IEEE80211_CONF_PS; 234 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS); 235 } 236 237 if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)) 238 /* 239 * If power save was enabled, no need to send a nullfunc 240 * frame because AP knows that we are sleeping. But if the 241 * hardware is creating the nullfunc frame for power save 242 * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not 243 * enabled) and power save was enabled, the firmware just 244 * sent a null frame with power save disabled. So we need 245 * to send a new nullfunc frame to inform the AP that we 246 * are again sleeping. 247 */ 248 ieee80211_send_nullfunc(local, sdata, 1); 249 } 250 251 /* inform AP that we are awake again, unless power save is enabled */ 252 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata) 253 { 254 struct ieee80211_local *local = sdata->local; 255 256 if (!local->powersave) 257 ieee80211_send_nullfunc(local, sdata, 0); 258 else { 259 /* 260 * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware 261 * will send a nullfunc frame with the powersave bit set 262 * even though the AP already knows that we are sleeping. 263 * This could be avoided by sending a null frame with power 264 * save bit disabled before enabling the power save, but 265 * this doesn't gain anything. 266 * 267 * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need 268 * to send a nullfunc frame because AP already knows that 269 * we are sleeping, let's just enable power save mode in 270 * hardware. 271 */ 272 local->hw.conf.flags |= IEEE80211_CONF_PS; 273 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS); 274 } 275 } 276 277 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted) 278 { 279 struct ieee80211_local *local = hw_to_local(hw); 280 struct ieee80211_sub_if_data *sdata; 281 282 if (WARN_ON(!local->hw_scanning && !local->sw_scanning)) 283 return; 284 285 if (WARN_ON(!local->scan_req)) 286 return; 287 288 if (local->scan_req != &local->int_scan_req) 289 cfg80211_scan_done(local->scan_req, aborted); 290 local->scan_req = NULL; 291 292 local->last_scan_completed = jiffies; 293 294 if (local->hw_scanning) { 295 local->hw_scanning = false; 296 /* 297 * Somebody might have requested channel change during scan 298 * that we won't have acted upon, try now. ieee80211_hw_config 299 * will set the flag based on actual changes. 300 */ 301 ieee80211_hw_config(local, 0); 302 goto done; 303 } 304 305 local->sw_scanning = false; 306 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL); 307 308 netif_tx_lock_bh(local->mdev); 309 netif_addr_lock(local->mdev); 310 local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC; 311 local->ops->configure_filter(local_to_hw(local), 312 FIF_BCN_PRBRESP_PROMISC, 313 &local->filter_flags, 314 local->mdev->mc_count, 315 local->mdev->mc_list); 316 317 netif_addr_unlock(local->mdev); 318 netif_tx_unlock_bh(local->mdev); 319 320 if (local->ops->sw_scan_complete) 321 local->ops->sw_scan_complete(local_to_hw(local)); 322 323 mutex_lock(&local->iflist_mtx); 324 list_for_each_entry(sdata, &local->interfaces, list) { 325 if (!netif_running(sdata->dev)) 326 continue; 327 328 /* Tell AP we're back */ 329 if (sdata->vif.type == NL80211_IFTYPE_STATION) { 330 if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) { 331 ieee80211_scan_ps_disable(sdata); 332 netif_tx_wake_all_queues(sdata->dev); 333 } 334 } else 335 netif_tx_wake_all_queues(sdata->dev); 336 337 /* re-enable beaconing */ 338 if (sdata->vif.type == NL80211_IFTYPE_AP || 339 sdata->vif.type == NL80211_IFTYPE_ADHOC || 340 sdata->vif.type == NL80211_IFTYPE_MESH_POINT) 341 ieee80211_if_config(sdata, 342 IEEE80211_IFCC_BEACON_ENABLED); 343 } 344 mutex_unlock(&local->iflist_mtx); 345 346 done: 347 ieee80211_mlme_notify_scan_completed(local); 348 ieee80211_ibss_notify_scan_completed(local); 349 ieee80211_mesh_notify_scan_completed(local); 350 } 351 EXPORT_SYMBOL(ieee80211_scan_completed); 352 353 void ieee80211_scan_work(struct work_struct *work) 354 { 355 struct ieee80211_local *local = 356 container_of(work, struct ieee80211_local, scan_work.work); 357 struct ieee80211_sub_if_data *sdata = local->scan_sdata; 358 struct ieee80211_channel *chan; 359 int skip, i; 360 unsigned long next_delay = 0; 361 362 /* 363 * Avoid re-scheduling when the sdata is going away. 364 */ 365 if (!netif_running(sdata->dev)) 366 return; 367 368 switch (local->scan_state) { 369 case SCAN_SET_CHANNEL: 370 /* if no more bands/channels left, complete scan */ 371 if (local->scan_channel_idx >= local->scan_req->n_channels) { 372 ieee80211_scan_completed(local_to_hw(local), false); 373 return; 374 } 375 skip = 0; 376 chan = local->scan_req->channels[local->scan_channel_idx]; 377 378 if (chan->flags & IEEE80211_CHAN_DISABLED || 379 (sdata->vif.type == NL80211_IFTYPE_ADHOC && 380 chan->flags & IEEE80211_CHAN_NO_IBSS)) 381 skip = 1; 382 383 if (!skip) { 384 local->scan_channel = chan; 385 if (ieee80211_hw_config(local, 386 IEEE80211_CONF_CHANGE_CHANNEL)) 387 skip = 1; 388 } 389 390 /* advance state machine to next channel/band */ 391 local->scan_channel_idx++; 392 393 if (skip) 394 break; 395 396 next_delay = IEEE80211_PROBE_DELAY + 397 usecs_to_jiffies(local->hw.channel_change_time); 398 local->scan_state = SCAN_SEND_PROBE; 399 break; 400 case SCAN_SEND_PROBE: 401 next_delay = IEEE80211_PASSIVE_CHANNEL_TIME; 402 local->scan_state = SCAN_SET_CHANNEL; 403 404 if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN || 405 !local->scan_req->n_ssids) 406 break; 407 for (i = 0; i < local->scan_req->n_ssids; i++) 408 ieee80211_send_probe_req( 409 sdata, NULL, 410 local->scan_req->ssids[i].ssid, 411 local->scan_req->ssids[i].ssid_len, 412 local->scan_req->ie, local->scan_req->ie_len); 413 next_delay = IEEE80211_CHANNEL_TIME; 414 break; 415 } 416 417 queue_delayed_work(local->hw.workqueue, &local->scan_work, 418 next_delay); 419 } 420 421 422 int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata, 423 struct cfg80211_scan_request *req) 424 { 425 struct ieee80211_local *local = scan_sdata->local; 426 struct ieee80211_sub_if_data *sdata; 427 428 if (!req) 429 return -EINVAL; 430 431 if (local->scan_req && local->scan_req != req) 432 return -EBUSY; 433 434 local->scan_req = req; 435 436 /* MLME-SCAN.request (page 118) page 144 (11.1.3.1) 437 * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS 438 * BSSID: MACAddress 439 * SSID 440 * ScanType: ACTIVE, PASSIVE 441 * ProbeDelay: delay (in microseconds) to be used prior to transmitting 442 * a Probe frame during active scanning 443 * ChannelList 444 * MinChannelTime (>= ProbeDelay), in TU 445 * MaxChannelTime: (>= MinChannelTime), in TU 446 */ 447 448 /* MLME-SCAN.confirm 449 * BSSDescriptionSet 450 * ResultCode: SUCCESS, INVALID_PARAMETERS 451 */ 452 453 if (local->sw_scanning || local->hw_scanning) { 454 if (local->scan_sdata == scan_sdata) 455 return 0; 456 return -EBUSY; 457 } 458 459 if (local->ops->hw_scan) { 460 int rc; 461 462 local->hw_scanning = true; 463 rc = local->ops->hw_scan(local_to_hw(local), req); 464 if (rc) { 465 local->hw_scanning = false; 466 return rc; 467 } 468 local->scan_sdata = scan_sdata; 469 return 0; 470 } 471 472 /* 473 * Hardware/driver doesn't support hw_scan, so use software 474 * scanning instead. First send a nullfunc frame with power save 475 * bit on so that AP will buffer the frames for us while we are not 476 * listening, then send probe requests to each channel and wait for 477 * the responses. After all channels are scanned, tune back to the 478 * original channel and send a nullfunc frame with power save bit 479 * off to trigger the AP to send us all the buffered frames. 480 * 481 * Note that while local->sw_scanning is true everything else but 482 * nullfunc frames and probe requests will be dropped in 483 * ieee80211_tx_h_check_assoc(). 484 */ 485 local->sw_scanning = true; 486 if (local->ops->sw_scan_start) 487 local->ops->sw_scan_start(local_to_hw(local)); 488 489 mutex_lock(&local->iflist_mtx); 490 list_for_each_entry(sdata, &local->interfaces, list) { 491 if (!netif_running(sdata->dev)) 492 continue; 493 494 /* disable beaconing */ 495 if (sdata->vif.type == NL80211_IFTYPE_AP || 496 sdata->vif.type == NL80211_IFTYPE_ADHOC || 497 sdata->vif.type == NL80211_IFTYPE_MESH_POINT) 498 ieee80211_if_config(sdata, 499 IEEE80211_IFCC_BEACON_ENABLED); 500 501 if (sdata->vif.type == NL80211_IFTYPE_STATION) { 502 if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) { 503 netif_tx_stop_all_queues(sdata->dev); 504 ieee80211_scan_ps_enable(sdata); 505 } 506 } else 507 netif_tx_stop_all_queues(sdata->dev); 508 } 509 mutex_unlock(&local->iflist_mtx); 510 511 local->scan_state = SCAN_SET_CHANNEL; 512 local->scan_channel_idx = 0; 513 local->scan_sdata = scan_sdata; 514 local->scan_req = req; 515 516 netif_addr_lock_bh(local->mdev); 517 local->filter_flags |= FIF_BCN_PRBRESP_PROMISC; 518 local->ops->configure_filter(local_to_hw(local), 519 FIF_BCN_PRBRESP_PROMISC, 520 &local->filter_flags, 521 local->mdev->mc_count, 522 local->mdev->mc_list); 523 netif_addr_unlock_bh(local->mdev); 524 525 /* TODO: start scan as soon as all nullfunc frames are ACKed */ 526 queue_delayed_work(local->hw.workqueue, &local->scan_work, 527 IEEE80211_CHANNEL_TIME); 528 529 return 0; 530 } 531 532 533 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata, 534 struct cfg80211_scan_request *req) 535 { 536 struct ieee80211_local *local = sdata->local; 537 struct ieee80211_if_managed *ifmgd; 538 539 if (!req) 540 return -EINVAL; 541 542 if (local->scan_req && local->scan_req != req) 543 return -EBUSY; 544 545 local->scan_req = req; 546 547 if (sdata->vif.type != NL80211_IFTYPE_STATION) 548 return ieee80211_start_scan(sdata, req); 549 550 /* 551 * STA has a state machine that might need to defer scanning 552 * while it's trying to associate/authenticate, therefore we 553 * queue it up to the state machine in that case. 554 */ 555 556 if (local->sw_scanning || local->hw_scanning) { 557 if (local->scan_sdata == sdata) 558 return 0; 559 return -EBUSY; 560 } 561 562 ifmgd = &sdata->u.mgd; 563 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request); 564 queue_work(local->hw.workqueue, &ifmgd->work); 565 566 return 0; 567 } 568