/* * 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 #include "ieee80211_i.h" #include "mesh.h" #define IEEE80211_PROBE_DELAY (HZ / 33) #define IEEE80211_CHANNEL_TIME (HZ / 33) #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5) 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 APs */ if (!elems->tim || 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; } void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid, int freq, u8 *ssid, u8 ssid_len) { struct ieee80211_bss *bss; struct ieee80211_local *local = sdata->local; bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len); if (bss) { cfg80211_unlink_bss(local->hw.wiphy, (void *)bss); ieee80211_rx_bss_put(local, bss); } } ieee80211_rx_result ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb, struct ieee80211_rx_status *rx_status) { 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; } void ieee80211_scan_failed(struct ieee80211_local *local) { if (WARN_ON(!local->scan_req)) return; /* notify cfg80211 about the failed scan */ if (local->scan_req != &local->int_scan_req) cfg80211_scan_done(local->scan_req, true); local->scan_req = NULL; } /* * 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; bool ps = 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) { ps = true; local->hw.conf.flags &= ~IEEE80211_CONF_PS; ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS); } if (!ps || !(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 { /* * 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); } } void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted) { struct ieee80211_local *local = hw_to_local(hw); struct ieee80211_sub_if_data *sdata; if (WARN_ON(!local->hw_scanning && !local->sw_scanning)) return; if (WARN_ON(!local->scan_req)) return; if (local->hw_scanning) { kfree(local->scan_req->ie); local->scan_req->ie = local->orig_ies; local->scan_req->ie_len = local->orig_ies_len; } if (local->scan_req != &local->int_scan_req) cfg80211_scan_done(local->scan_req, aborted); local->scan_req = NULL; if (local->hw_scanning) { local->hw_scanning = false; /* * Somebody might have requested channel change during scan * that we won't have acted upon, try now. ieee80211_hw_config * will set the flag based on actual changes. */ ieee80211_hw_config(local, 0); goto done; } local->sw_scanning = false; ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL); netif_tx_lock_bh(local->mdev); netif_addr_lock(local->mdev); local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC; local->ops->configure_filter(local_to_hw(local), FIF_BCN_PRBRESP_PROMISC, &local->filter_flags, local->mdev->mc_count, local->mdev->mc_list); netif_addr_unlock(local->mdev); netif_tx_unlock_bh(local->mdev); if (local->ops->sw_scan_complete) local->ops->sw_scan_complete(local_to_hw(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.flags & IEEE80211_STA_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_if_config(sdata, IEEE80211_IFCC_BEACON_ENABLED); } mutex_unlock(&local->iflist_mtx); done: ieee80211_mlme_notify_scan_completed(local); ieee80211_ibss_notify_scan_completed(local); ieee80211_mesh_notify_scan_completed(local); } EXPORT_SYMBOL(ieee80211_scan_completed); 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; struct ieee80211_channel *chan; int skip, i; unsigned long next_delay = 0; /* * Avoid re-scheduling when the sdata is going away. */ if (!netif_running(sdata->dev)) return; switch (local->scan_state) { case SCAN_SET_CHANNEL: /* if no more bands/channels left, complete scan */ if (local->scan_channel_idx >= local->scan_req->n_channels) { ieee80211_scan_completed(local_to_hw(local), false); return; } 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) break; next_delay = IEEE80211_PROBE_DELAY + usecs_to_jiffies(local->hw.channel_change_time); local->scan_state = SCAN_SEND_PROBE; break; case SCAN_SEND_PROBE: next_delay = IEEE80211_PASSIVE_CHANNEL_TIME; local->scan_state = SCAN_SET_CHANNEL; if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN || !local->scan_req->n_ssids) break; 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); next_delay = IEEE80211_CHANNEL_TIME; break; } queue_delayed_work(local->hw.workqueue, &local->scan_work, next_delay); } int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata, struct cfg80211_scan_request *req) { struct ieee80211_local *local = scan_sdata->local; struct ieee80211_sub_if_data *sdata; if (!req) return -EINVAL; if (local->scan_req && local->scan_req != req) return -EBUSY; local->scan_req = req; /* MLME-SCAN.request (page 118) page 144 (11.1.3.1) * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS * BSSID: MACAddress * SSID * ScanType: ACTIVE, PASSIVE * ProbeDelay: delay (in microseconds) to be used prior to transmitting * a Probe frame during active scanning * ChannelList * MinChannelTime (>= ProbeDelay), in TU * MaxChannelTime: (>= MinChannelTime), in TU */ /* MLME-SCAN.confirm * BSSDescriptionSet * ResultCode: SUCCESS, INVALID_PARAMETERS */ if (local->sw_scanning || local->hw_scanning) { if (local->scan_sdata == scan_sdata) return 0; return -EBUSY; } if (local->ops->hw_scan) { u8 *ies; int rc, 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->hw_scanning = true; rc = local->ops->hw_scan(local_to_hw(local), req); if (rc) { local->hw_scanning = false; kfree(ies); req->ie_len = local->orig_ies_len; req->ie = local->orig_ies; return rc; } local->scan_sdata = scan_sdata; return 0; } /* * 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(). */ local->sw_scanning = true; if (local->ops->sw_scan_start) local->ops->sw_scan_start(local_to_hw(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_if_config(sdata, IEEE80211_IFCC_BEACON_ENABLED); if (sdata->vif.type == NL80211_IFTYPE_STATION) { if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) { netif_tx_stop_all_queues(sdata->dev); ieee80211_scan_ps_enable(sdata); } } else netif_tx_stop_all_queues(sdata->dev); } mutex_unlock(&local->iflist_mtx); local->scan_state = SCAN_SET_CHANNEL; local->scan_channel_idx = 0; local->scan_sdata = scan_sdata; local->scan_req = req; netif_addr_lock_bh(local->mdev); local->filter_flags |= FIF_BCN_PRBRESP_PROMISC; local->ops->configure_filter(local_to_hw(local), FIF_BCN_PRBRESP_PROMISC, &local->filter_flags, local->mdev->mc_count, local->mdev->mc_list); netif_addr_unlock_bh(local->mdev); /* TODO: start scan as soon as all nullfunc frames are ACKed */ queue_delayed_work(local->hw.workqueue, &local->scan_work, IEEE80211_CHANNEL_TIME); return 0; } int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata, struct cfg80211_scan_request *req) { struct ieee80211_local *local = sdata->local; struct ieee80211_if_managed *ifmgd; if (!req) return -EINVAL; if (local->scan_req && local->scan_req != req) return -EBUSY; local->scan_req = req; if (sdata->vif.type != NL80211_IFTYPE_STATION) return ieee80211_start_scan(sdata, req); /* * STA has a state machine that might need to defer scanning * while it's trying to associate/authenticate, therefore we * queue it up to the state machine in that case. */ if (local->sw_scanning || local->hw_scanning) { if (local->scan_sdata == sdata) return 0; return -EBUSY; } ifmgd = &sdata->u.mgd; set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request); queue_work(local->hw.workqueue, &ifmgd->work); return 0; }