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af88b9078d
linux/net/mac80211/scan.c
Helmut Schaa af88b9078d mac80211: handle failed scan requests in STA mode 
If cfg80211 requests a scan it awaits either a return code != 0 from
the scan function or the cfg80211_scan_done to be called. In case of
a STA mac80211's scan function ever returns 0 and queues the scan request.
If ieee80211_sta_work is executed and ieee80211_start_scan fails for
some reason cfg80211_scan_done will never be called but cfg80211 still
thinks the scan was triggered successfully and will refuse any future
scan requests due to drv->scan_req not being cleaned up.

If a scan is triggered from within the MLME a similar problem appears. If
ieee80211_start_scan returns an error, local->scan_req will not be reset
and mac80211 will refuse any future scan requests.

Hence, in both cases call ieee80211_scan_failed (which notifies cfg80211
and resets local->scan_req) if ieee80211_start_scan returns an error.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2009-03-16 18:09:38 -04:00

495 lines
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/*
* 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 <net/iw_handler.h>
#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;
}
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->scan_req != &local->int_scan_req)
cfg80211_scan_done(local->scan_req, aborted);
local->scan_req = NULL;
local->last_scan_completed = jiffies;
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_send_nullfunc(local, sdata, 0);
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) {
int rc;
local->hw_scanning = true;
rc = local->ops->hw_scan(local_to_hw(local), req);
if (rc) {
local->hw_scanning = false;
return rc;
}
local->scan_sdata = scan_sdata;
return 0;
}
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_send_nullfunc(local, sdata, 1);
}
} 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;
}
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