/* * 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. */ /* TODO: figure out how to avoid that the "current BSS" expires */ #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) { return (void *)cfg80211_get_bss(local->hw.wiphy, ieee80211_get_channel(local->hw.wiphy, freq), bssid, ssid, ssid_len, 0, 0); } static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss) { struct ieee80211_bss *bss = (void *)cbss; kfree(bss_mesh_id(bss)); kfree(bss_mesh_cfg(bss)); } void ieee80211_rx_bss_put(struct ieee80211_local *local, struct ieee80211_bss *bss) { cfg80211_put_bss((struct cfg80211_bss *)bss); } 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 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; bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel, mgmt, len, signal, GFP_ATOMIC); if (!bss) return NULL; bss->cbss.free_priv = ieee80211_rx_bss_free; /* 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; } /* set default value for buggy AP/no TIM element */ if (bss->dtim_period == 0) bss->dtim_period = 1; 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; 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->dev->dev_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; } /* * inform AP that we will go to sleep so that it will buffer the frames * while we scan */ static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata) { struct ieee80211_local *local = sdata->local; local->scan_ps_enabled = false; /* FIXME: what to do when local->pspolling is true? */ del_timer_sync(&local->dynamic_ps_timer); cancel_work_sync(&local->dynamic_ps_enable_work); if (local->hw.conf.flags & IEEE80211_CONF_PS) { local->scan_ps_enabled = true; local->hw.conf.flags &= ~IEEE80211_CONF_PS; ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS); } if (!(local->scan_ps_enabled) || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)) /* * If power save was enabled, no need to send a nullfunc * frame because AP knows that we are sleeping. But if the * hardware is creating the nullfunc frame for power save * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not * enabled) and power save was enabled, the firmware just * sent a null frame with power save disabled. So we need * to send a new nullfunc frame to inform the AP that we * are again sleeping. */ ieee80211_send_nullfunc(local, sdata, 1); } /* inform AP that we are awake again, unless power save is enabled */ static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata) { struct ieee80211_local *local = sdata->local; if (!local->ps_sdata) ieee80211_send_nullfunc(local, sdata, 0); else if (local->scan_ps_enabled) { /* * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware * will send a nullfunc frame with the powersave bit set * even though the AP already knows that we are sleeping. * This could be avoided by sending a null frame with power * save bit disabled before enabling the power save, but * this doesn't gain anything. * * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need * to send a nullfunc frame because AP already knows that * we are sleeping, let's just enable power save mode in * hardware. */ local->hw.conf.flags |= IEEE80211_CONF_PS; ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS); } else if (local->hw.conf.dynamic_ps_timeout > 0) { /* * If IEEE80211_CONF_PS was not set and the dynamic_ps_timer * had been running before leaving the operating channel, * restart the timer now and send a nullfunc frame to inform * the AP that we are awake. */ ieee80211_send_nullfunc(local, sdata, 0); mod_timer(&local->dynamic_ps_timer, jiffies + msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout)); } } static void ieee80211_restore_scan_ies(struct ieee80211_local *local) { kfree(local->scan_req->ie); local->scan_req->ie = local->orig_ies; local->scan_req->ie_len = local->orig_ies_len; } void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted) { struct ieee80211_local *local = hw_to_local(hw); struct ieee80211_sub_if_data *sdata; 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; } if (test_bit(SCAN_HW_SCANNING, &local->scanning)) ieee80211_restore_scan_ies(local); if (local->scan_req != local->int_scan_req) cfg80211_scan_done(local->scan_req, aborted); local->scan_req = NULL; local->scan_sdata = NULL; was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning); 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); mutex_lock(&local->iflist_mtx); list_for_each_entry(sdata, &local->interfaces, list) { if (!netif_running(sdata->dev)) continue; /* Tell AP we're back */ if (sdata->vif.type == NL80211_IFTYPE_STATION) { if (sdata->u.mgd.associated) { ieee80211_scan_ps_disable(sdata); netif_tx_wake_all_queues(sdata->dev); } } else netif_tx_wake_all_queues(sdata->dev); /* re-enable beaconing */ if (sdata->vif.type == NL80211_IFTYPE_AP || sdata->vif.type == NL80211_IFTYPE_ADHOC || sdata->vif.type == NL80211_IFTYPE_MESH_POINT) ieee80211_bss_info_change_notify( sdata, BSS_CHANGED_BEACON_ENABLED); } mutex_unlock(&local->iflist_mtx); done: ieee80211_recalc_idle(local); ieee80211_mlme_notify_scan_completed(local); ieee80211_ibss_notify_scan_completed(local); ieee80211_mesh_notify_scan_completed(local); } EXPORT_SYMBOL(ieee80211_scan_completed); static int ieee80211_start_sw_scan(struct ieee80211_local *local) { struct ieee80211_sub_if_data *sdata; /* * 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); mutex_lock(&local->iflist_mtx); list_for_each_entry(sdata, &local->interfaces, list) { if (!netif_running(sdata->dev)) continue; /* disable beaconing */ if (sdata->vif.type == NL80211_IFTYPE_AP || sdata->vif.type == NL80211_IFTYPE_ADHOC || sdata->vif.type == NL80211_IFTYPE_MESH_POINT) ieee80211_bss_info_change_notify( sdata, BSS_CHANGED_BEACON_ENABLED); /* * only handle non-STA interfaces here, STA interfaces * are handled in the scan state machine */ if (sdata->vif.type != NL80211_IFTYPE_STATION) netif_tx_stop_all_queues(sdata->dev); } mutex_unlock(&local->iflist_mtx); local->next_scan_state = SCAN_DECISION; local->scan_channel_idx = 0; ieee80211_configure_filter(local); /* TODO: start scan as soon as all nullfunc frames are ACKed */ 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; struct ieee80211_if_managed *ifmgd = &sdata->u.mgd; int rc; if (local->scan_req) return -EBUSY; if (local->ops->hw_scan) { u8 *ies; int ielen; ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len + req->ie_len, GFP_KERNEL); if (!ies) return -ENOMEM; ielen = ieee80211_build_preq_ies(local, ies, req->ie, req->ie_len); local->orig_ies = req->ie; local->orig_ies_len = req->ie_len; req->ie = ies; req->ie_len = ielen; } local->scan_req = req; local->scan_sdata = sdata; if (req != local->int_scan_req && sdata->vif.type == NL80211_IFTYPE_STATION && !list_empty(&ifmgd->work_list)) { /* actually wait for the work it's doing to finish/time out */ set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request); return 0; } 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 getting a scan_mtx -> iflist_mtx * dependency, so that the scan completed calls * have more locking freedom. */ ieee80211_recalc_idle(local); mutex_unlock(&local->scan_mtx); if (local->ops->hw_scan) rc = drv_hw_scan(local, local->scan_req); else rc = ieee80211_start_sw_scan(local); mutex_lock(&local->scan_mtx); if (rc) { if (local->ops->hw_scan) ieee80211_restore_scan_ies(local); local->scanning = 0; ieee80211_recalc_idle(local); local->scan_req = NULL; local->scan_sdata = NULL; } return rc; } static int ieee80211_scan_state_decision(struct ieee80211_local *local, unsigned long *next_delay) { bool associated = false; struct ieee80211_sub_if_data *sdata; /* 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 */ mutex_lock(&local->iflist_mtx); list_for_each_entry(sdata, &local->interfaces, list) { if (!netif_running(sdata->dev)) continue; if (sdata->vif.type == NL80211_IFTYPE_STATION) { if (sdata->u.mgd.associated) { associated = true; break; } } } mutex_unlock(&local->iflist_mtx); if (local->scan_channel) { /* * we're currently scanning a different channel, let's * switch back to the operating channel now if at least * one interface is associated. Otherwise just scan the * next channel */ if (associated) 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) { struct ieee80211_sub_if_data *sdata; /* * notify the AP about us leaving the channel and stop all STA interfaces */ mutex_lock(&local->iflist_mtx); list_for_each_entry(sdata, &local->interfaces, list) { if (!netif_running(sdata->dev)) continue; if (sdata->vif.type == NL80211_IFTYPE_STATION) { netif_tx_stop_all_queues(sdata->dev); if (sdata->u.mgd.associated) ieee80211_scan_ps_enable(sdata); } } mutex_unlock(&local->iflist_mtx); __set_bit(SCAN_OFF_CHANNEL, &local->scanning); /* advance to the next channel to be scanned */ *next_delay = HZ / 10; local->next_scan_state = SCAN_SET_CHANNEL; } static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local, unsigned long *next_delay) { struct ieee80211_sub_if_data *sdata = local->scan_sdata; /* switch back to the operating channel */ local->scan_channel = NULL; ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL); /* * notify the AP about us being back and restart all STA interfaces */ mutex_lock(&local->iflist_mtx); list_for_each_entry(sdata, &local->interfaces, list) { if (!netif_running(sdata->dev)) continue; /* Tell AP we're back */ if (sdata->vif.type == NL80211_IFTYPE_STATION) { if (sdata->u.mgd.associated) ieee80211_scan_ps_disable(sdata); netif_tx_wake_all_queues(sdata->dev); } } mutex_unlock(&local->iflist_mtx); __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; struct ieee80211_sub_if_data *sdata = local->scan_sdata; skip = 0; chan = local->scan_req->channels[local->scan_channel_idx]; if (chan->flags & IEEE80211_CHAN_DISABLED || (sdata->vif.type == NL80211_IFTYPE_ADHOC && chan->flags & IEEE80211_CHAN_NO_IBSS)) skip = 1; if (!skip) { 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->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 (!netif_running(sdata->dev)) { 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); }