/*
* Scanning implementation
*
* Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
* Copyright 2004, Instant802 Networks, Inc.
* Copyright 2005, Devicescape Software, Inc.
* Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
* Copyright 2007, Michael Wu <flamingice@sourmilk.net>
*
* 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 <linux/wireless.h>
#include <linux/if_arp.h>
#include <linux/rtnetlink.h>
#include <net/mac80211.h>
#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;
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);
}
}
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);
if (WARN_ON(!local->scanning)) {
mutex_unlock(&local->scan_mtx);
return;
}
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_wake_queue(sdata->dev);
}
} else
netif_wake_queue(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_stop_queue(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_stop_queue(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_wake_queue(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);
}