/* * Scanning implementation * * Copyright 2003, Jouni Malinen * Copyright 2004, Instant802 Networks, Inc. * Copyright 2005, Devicescape Software, Inc. * Copyright 2006-2007 Jiri Benc * Copyright 2007, Michael Wu * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include "ieee80211_i.h" #include "driver-ops.h" #include "mesh.h" #define IEEE80211_PROBE_DELAY (HZ / 33) #define IEEE80211_CHANNEL_TIME (HZ / 33) #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8) struct ieee80211_bss * ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq, u8 *ssid, u8 ssid_len) { struct cfg80211_bss *cbss; cbss = cfg80211_get_bss(local->hw.wiphy, ieee80211_get_channel(local->hw.wiphy, freq), bssid, ssid, ssid_len, 0, 0); if (!cbss) return NULL; return (void *)cbss->priv; } static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss) { struct ieee80211_bss *bss = (void *)cbss->priv; kfree(bss_mesh_id(bss)); kfree(bss_mesh_cfg(bss)); } void ieee80211_rx_bss_put(struct ieee80211_local *local, struct ieee80211_bss *bss) { if (!bss) return; cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv)); } static bool is_uapsd_supported(struct ieee802_11_elems *elems) { u8 qos_info; if (elems->wmm_info && elems->wmm_info_len == 7 && elems->wmm_info[5] == 1) qos_info = elems->wmm_info[6]; else if (elems->wmm_param && elems->wmm_param_len == 24 && elems->wmm_param[5] == 1) qos_info = elems->wmm_param[6]; else /* no valid wmm information or parameter element found */ return false; return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD; } struct ieee80211_bss * ieee80211_bss_info_update(struct ieee80211_local *local, struct ieee80211_rx_status *rx_status, struct ieee80211_mgmt *mgmt, size_t len, struct ieee802_11_elems *elems, struct ieee80211_channel *channel, bool beacon) { struct cfg80211_bss *cbss; struct ieee80211_bss *bss; int clen; s32 signal = 0; if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM) signal = rx_status->signal * 100; else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC) signal = (rx_status->signal * 100) / local->hw.max_signal; cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel, mgmt, len, signal, GFP_ATOMIC); if (!cbss) return NULL; cbss->free_priv = ieee80211_rx_bss_free; bss = (void *)cbss->priv; /* save the ERP value so that it is available at association time */ if (elems->erp_info && elems->erp_info_len >= 1) { bss->erp_value = elems->erp_info[0]; bss->has_erp_value = 1; } if (elems->tim) { struct ieee80211_tim_ie *tim_ie = (struct ieee80211_tim_ie *)elems->tim; bss->dtim_period = tim_ie->dtim_period; } bss->supp_rates_len = 0; if (elems->supp_rates) { clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len; if (clen > elems->supp_rates_len) clen = elems->supp_rates_len; memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates, clen); bss->supp_rates_len += clen; } if (elems->ext_supp_rates) { clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len; if (clen > elems->ext_supp_rates_len) clen = elems->ext_supp_rates_len; memcpy(&bss->supp_rates[bss->supp_rates_len], elems->ext_supp_rates, clen); bss->supp_rates_len += clen; } bss->wmm_used = elems->wmm_param || elems->wmm_info; bss->uapsd_supported = is_uapsd_supported(elems); if (!beacon) bss->last_probe_resp = jiffies; return bss; } ieee80211_rx_result ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb) { struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb); struct ieee80211_mgmt *mgmt; struct ieee80211_bss *bss; u8 *elements; struct ieee80211_channel *channel; size_t baselen; int freq; __le16 fc; bool presp, beacon = false; struct ieee802_11_elems elems; if (skb->len < 2) return RX_DROP_UNUSABLE; mgmt = (struct ieee80211_mgmt *) skb->data; fc = mgmt->frame_control; if (ieee80211_is_ctl(fc)) return RX_CONTINUE; if (skb->len < 24) return RX_DROP_MONITOR; presp = ieee80211_is_probe_resp(fc); if (presp) { /* ignore ProbeResp to foreign address */ if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN)) return RX_DROP_MONITOR; presp = true; elements = mgmt->u.probe_resp.variable; baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable); } else { beacon = ieee80211_is_beacon(fc); baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable); elements = mgmt->u.beacon.variable; } if (!presp && !beacon) return RX_CONTINUE; if (baselen > skb->len) return RX_DROP_MONITOR; ieee802_11_parse_elems(elements, skb->len - baselen, &elems); if (elems.ds_params && elems.ds_params_len == 1) freq = ieee80211_channel_to_frequency(elems.ds_params[0]); else freq = rx_status->freq; channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq); if (!channel || channel->flags & IEEE80211_CHAN_DISABLED) return RX_DROP_MONITOR; bss = ieee80211_bss_info_update(sdata->local, rx_status, mgmt, skb->len, &elems, channel, beacon); if (bss) ieee80211_rx_bss_put(sdata->local, bss); dev_kfree_skb(skb); return RX_QUEUED; } /* return false if no more work */ static bool ieee80211_prep_hw_scan(struct ieee80211_local *local) { struct cfg80211_scan_request *req = local->scan_req; enum ieee80211_band band; int i, ielen, n_chans; do { if (local->hw_scan_band == IEEE80211_NUM_BANDS) return false; band = local->hw_scan_band; n_chans = 0; for (i = 0; i < req->n_channels; i++) { if (req->channels[i]->band == band) { local->hw_scan_req->channels[n_chans] = req->channels[i]; n_chans++; } } local->hw_scan_band++; } while (!n_chans); local->hw_scan_req->n_channels = n_chans; ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie, req->ie, req->ie_len, band); local->hw_scan_req->ie_len = ielen; return true; } void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted) { struct ieee80211_local *local = hw_to_local(hw); bool was_hw_scan; mutex_lock(&local->scan_mtx); /* * It's ok to abort a not-yet-running scan (that * we have one at all will be verified by checking * local->scan_req next), but not to complete it * successfully. */ if (WARN_ON(!local->scanning && !aborted)) aborted = true; if (WARN_ON(!local->scan_req)) { mutex_unlock(&local->scan_mtx); return; } was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning); if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) { ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0); mutex_unlock(&local->scan_mtx); return; } kfree(local->hw_scan_req); local->hw_scan_req = NULL; if (local->scan_req != local->int_scan_req) cfg80211_scan_done(local->scan_req, aborted); local->scan_req = NULL; local->scan_sdata = NULL; local->scanning = 0; local->scan_channel = NULL; /* we only have to protect scan_req and hw/sw scan */ mutex_unlock(&local->scan_mtx); ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL); if (was_hw_scan) goto done; ieee80211_configure_filter(local); drv_sw_scan_complete(local); ieee80211_offchannel_return(local, true); done: ieee80211_recalc_idle(local); ieee80211_mlme_notify_scan_completed(local); ieee80211_ibss_notify_scan_completed(local); ieee80211_mesh_notify_scan_completed(local); ieee80211_queue_work(&local->hw, &local->work_work); } EXPORT_SYMBOL(ieee80211_scan_completed); static int ieee80211_start_sw_scan(struct ieee80211_local *local) { /* * Hardware/driver doesn't support hw_scan, so use software * scanning instead. First send a nullfunc frame with power save * bit on so that AP will buffer the frames for us while we are not * listening, then send probe requests to each channel and wait for * the responses. After all channels are scanned, tune back to the * original channel and send a nullfunc frame with power save bit * off to trigger the AP to send us all the buffered frames. * * Note that while local->sw_scanning is true everything else but * nullfunc frames and probe requests will be dropped in * ieee80211_tx_h_check_assoc(). */ drv_sw_scan_start(local); ieee80211_offchannel_stop_beaconing(local); local->leave_oper_channel_time = 0; local->next_scan_state = SCAN_DECISION; local->scan_channel_idx = 0; drv_flush(local, false); ieee80211_configure_filter(local); ieee80211_queue_delayed_work(&local->hw, &local->scan_work, IEEE80211_CHANNEL_TIME); return 0; } static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata, struct cfg80211_scan_request *req) { struct ieee80211_local *local = sdata->local; int rc; if (local->scan_req) return -EBUSY; if (!list_empty(&local->work_list)) { /* wait for the work to finish/time out */ local->scan_req = req; local->scan_sdata = sdata; return 0; } if (local->ops->hw_scan) { u8 *ies; local->hw_scan_req = kmalloc( sizeof(*local->hw_scan_req) + req->n_channels * sizeof(req->channels[0]) + 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len + req->ie_len, GFP_KERNEL); if (!local->hw_scan_req) return -ENOMEM; local->hw_scan_req->ssids = req->ssids; local->hw_scan_req->n_ssids = req->n_ssids; ies = (u8 *)local->hw_scan_req + sizeof(*local->hw_scan_req) + req->n_channels * sizeof(req->channels[0]); local->hw_scan_req->ie = ies; local->hw_scan_band = 0; /* * After allocating local->hw_scan_req, we must * go through until ieee80211_prep_hw_scan(), so * anything that might be changed here and leave * this function early must not go after this * allocation. */ } local->scan_req = req; local->scan_sdata = sdata; if (local->ops->hw_scan) __set_bit(SCAN_HW_SCANNING, &local->scanning); else __set_bit(SCAN_SW_SCANNING, &local->scanning); /* * Kicking off the scan need not be protected, * only the scan variable stuff, since now * local->scan_req is assigned and other callers * will abort their scan attempts. * * This avoids too many locking dependencies * so that the scan completed calls have more * locking freedom. */ ieee80211_recalc_idle(local); mutex_unlock(&local->scan_mtx); if (local->ops->hw_scan) { WARN_ON(!ieee80211_prep_hw_scan(local)); rc = drv_hw_scan(local, local->hw_scan_req); } else rc = ieee80211_start_sw_scan(local); mutex_lock(&local->scan_mtx); if (rc) { kfree(local->hw_scan_req); local->hw_scan_req = NULL; local->scanning = 0; ieee80211_recalc_idle(local); local->scan_req = NULL; local->scan_sdata = NULL; } return rc; } static unsigned long ieee80211_scan_get_channel_time(struct ieee80211_channel *chan) { /* * TODO: channel switching also consumes quite some time, * add that delay as well to get a better estimation */ if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN) return IEEE80211_PASSIVE_CHANNEL_TIME; return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME; } static int ieee80211_scan_state_decision(struct ieee80211_local *local, unsigned long *next_delay) { bool associated = false; bool tx_empty = true; bool bad_latency; bool listen_int_exceeded; unsigned long min_beacon_int = 0; struct ieee80211_sub_if_data *sdata; struct ieee80211_channel *next_chan; /* if no more bands/channels left, complete scan and advance to the idle state */ if (local->scan_channel_idx >= local->scan_req->n_channels) { ieee80211_scan_completed(&local->hw, false); return 1; } /* * check if at least one STA interface is associated, * check if at least one STA interface has pending tx frames * and grab the lowest used beacon interval */ mutex_lock(&local->iflist_mtx); list_for_each_entry(sdata, &local->interfaces, list) { if (!ieee80211_sdata_running(sdata)) continue; if (sdata->vif.type == NL80211_IFTYPE_STATION) { if (sdata->u.mgd.associated) { associated = true; if (sdata->vif.bss_conf.beacon_int < min_beacon_int || min_beacon_int == 0) min_beacon_int = sdata->vif.bss_conf.beacon_int; if (!qdisc_all_tx_empty(sdata->dev)) { tx_empty = false; break; } } } } mutex_unlock(&local->iflist_mtx); if (local->scan_channel) { /* * we're currently scanning a different channel, let's * see if we can scan another channel without interfering * with the current traffic situation. * * Since we don't know if the AP has pending frames for us * we can only check for our tx queues and use the current * pm_qos requirements for rx. Hence, if no tx traffic occurs * at all we will scan as many channels in a row as the pm_qos * latency allows us to. Additionally we also check for the * currently negotiated listen interval to prevent losing * frames unnecessarily. * * Otherwise switch back to the operating channel. */ next_chan = local->scan_req->channels[local->scan_channel_idx]; bad_latency = time_after(jiffies + ieee80211_scan_get_channel_time(next_chan), local->leave_oper_channel_time + usecs_to_jiffies(pm_qos_requirement(PM_QOS_NETWORK_LATENCY))); listen_int_exceeded = time_after(jiffies + ieee80211_scan_get_channel_time(next_chan), local->leave_oper_channel_time + usecs_to_jiffies(min_beacon_int * 1024) * local->hw.conf.listen_interval); if (associated && ( !tx_empty || bad_latency || listen_int_exceeded)) local->next_scan_state = SCAN_ENTER_OPER_CHANNEL; else local->next_scan_state = SCAN_SET_CHANNEL; } else { /* * we're on the operating channel currently, let's * leave that channel now to scan another one */ local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL; } *next_delay = 0; return 0; } static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local, unsigned long *next_delay) { ieee80211_offchannel_stop_station(local); __set_bit(SCAN_OFF_CHANNEL, &local->scanning); /* * What if the nullfunc frames didn't arrive? */ drv_flush(local, false); if (local->ops->flush) *next_delay = 0; else *next_delay = HZ / 10; /* remember when we left the operating channel */ local->leave_oper_channel_time = jiffies; /* advance to the next channel to be scanned */ local->next_scan_state = SCAN_SET_CHANNEL; } static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local, unsigned long *next_delay) { /* switch back to the operating channel */ local->scan_channel = NULL; ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL); /* * Only re-enable station mode interface now; beaconing will be * re-enabled once the full scan has been completed. */ ieee80211_offchannel_return(local, false); __clear_bit(SCAN_OFF_CHANNEL, &local->scanning); *next_delay = HZ / 5; local->next_scan_state = SCAN_DECISION; } static void ieee80211_scan_state_set_channel(struct ieee80211_local *local, unsigned long *next_delay) { int skip; struct ieee80211_channel *chan; skip = 0; chan = local->scan_req->channels[local->scan_channel_idx]; local->scan_channel = chan; if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL)) skip = 1; /* advance state machine to next channel/band */ local->scan_channel_idx++; if (skip) { /* if we skip this channel return to the decision state */ local->next_scan_state = SCAN_DECISION; return; } /* * Probe delay is used to update the NAV, cf. 11.1.3.2.2 * (which unfortunately doesn't say _why_ step a) is done, * but it waits for the probe delay or until a frame is * received - and the received frame would update the NAV). * For now, we do not support waiting until a frame is * received. * * In any case, it is not necessary for a passive scan. */ if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN || !local->scan_req->n_ssids) { *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME; local->next_scan_state = SCAN_DECISION; return; } /* active scan, send probes */ *next_delay = IEEE80211_PROBE_DELAY; local->next_scan_state = SCAN_SEND_PROBE; } static void ieee80211_scan_state_send_probe(struct ieee80211_local *local, unsigned long *next_delay) { int i; struct ieee80211_sub_if_data *sdata = local->scan_sdata; for (i = 0; i < local->scan_req->n_ssids; i++) ieee80211_send_probe_req( sdata, NULL, local->scan_req->ssids[i].ssid, local->scan_req->ssids[i].ssid_len, local->scan_req->ie, local->scan_req->ie_len); /* * After sending probe requests, wait for probe responses * on the channel. */ *next_delay = IEEE80211_CHANNEL_TIME; local->next_scan_state = SCAN_DECISION; } void ieee80211_scan_work(struct work_struct *work) { struct ieee80211_local *local = container_of(work, struct ieee80211_local, scan_work.work); struct ieee80211_sub_if_data *sdata = local->scan_sdata; unsigned long next_delay = 0; mutex_lock(&local->scan_mtx); if (!sdata || !local->scan_req) { mutex_unlock(&local->scan_mtx); return; } if (local->hw_scan_req) { int rc = drv_hw_scan(local, local->hw_scan_req); mutex_unlock(&local->scan_mtx); if (rc) ieee80211_scan_completed(&local->hw, true); return; } if (local->scan_req && !local->scanning) { struct cfg80211_scan_request *req = local->scan_req; int rc; local->scan_req = NULL; local->scan_sdata = NULL; rc = __ieee80211_start_scan(sdata, req); mutex_unlock(&local->scan_mtx); if (rc) ieee80211_scan_completed(&local->hw, true); return; } mutex_unlock(&local->scan_mtx); /* * Avoid re-scheduling when the sdata is going away. */ if (!ieee80211_sdata_running(sdata)) { ieee80211_scan_completed(&local->hw, true); return; } /* * as long as no delay is required advance immediately * without scheduling a new work */ do { switch (local->next_scan_state) { case SCAN_DECISION: if (ieee80211_scan_state_decision(local, &next_delay)) return; break; case SCAN_SET_CHANNEL: ieee80211_scan_state_set_channel(local, &next_delay); break; case SCAN_SEND_PROBE: ieee80211_scan_state_send_probe(local, &next_delay); break; case SCAN_LEAVE_OPER_CHANNEL: ieee80211_scan_state_leave_oper_channel(local, &next_delay); break; case SCAN_ENTER_OPER_CHANNEL: ieee80211_scan_state_enter_oper_channel(local, &next_delay); break; } } while (next_delay == 0); ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay); } int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata, struct cfg80211_scan_request *req) { int res; mutex_lock(&sdata->local->scan_mtx); res = __ieee80211_start_scan(sdata, req); mutex_unlock(&sdata->local->scan_mtx); return res; } int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata, const u8 *ssid, u8 ssid_len) { struct ieee80211_local *local = sdata->local; int ret = -EBUSY; mutex_lock(&local->scan_mtx); /* busy scanning */ if (local->scan_req) goto unlock; memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN); local->int_scan_req->ssids[0].ssid_len = ssid_len; ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req); unlock: mutex_unlock(&local->scan_mtx); return ret; } void ieee80211_scan_cancel(struct ieee80211_local *local) { bool abortscan; cancel_delayed_work_sync(&local->scan_work); /* * Only call this function when a scan can't be * queued -- mostly at suspend under RTNL. */ mutex_lock(&local->scan_mtx); abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) || (!local->scanning && local->scan_req); mutex_unlock(&local->scan_mtx); if (abortscan) ieee80211_scan_completed(&local->hw, true); }