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 } 708