linux/net/mac80211/ht.c
Johannes Berg 827d42c9ac mac80211: fix spurious delBA handling
Lennert Buytenhek noticed that delBA handling in mac80211
was broken and has remotely triggerable problems, some of
which are due to some code shuffling I did that ended up
changing the order in which things were done -- this was

  commit d75636ef9c
  Author: Johannes Berg <johannes@sipsolutions.net>
  Date:   Tue Feb 10 21:25:53 2009 +0100

    mac80211: RX aggregation: clean up stop session

and other parts were already present in the original

  commit d92684e660
  Author: Ron Rindjunsky <ron.rindjunsky@intel.com>
  Date:   Mon Jan 28 14:07:22 2008 +0200

      mac80211: A-MPDU Tx add delBA from recipient support

The first problem is that I moved a BUG_ON before various
checks -- thereby making it possible to hit. As the comment
indicates, the BUG_ON can be removed since the ampdu_action
callback must already exist when the state is != IDLE.

The second problem isn't easily exploitable but there's a
race condition due to unconditionally setting the state to
OPERATIONAL when a delBA frame is received, even when no
aggregation session was ever initiated. All the drivers
accept stopping the session even then, but that opens a
race window where crashes could happen before the driver
accepts it. Right now, a WARN_ON may happen with non-HT
drivers, while the race opens only for HT drivers.

For this case, there are two things necessary to fix it:
 1) don't process spurious delBA frames, and be more careful
    about the session state; don't drop the lock

 2) HT drivers need to be prepared to handle a session stop
    even before the session was really started -- this is
    true for all drivers (that support aggregation) but
    iwlwifi which can be fixed easily. The other HT drivers
    (ath9k and ar9170) are behaving properly already.

Reported-by: Lennert Buytenhek <buytenh@marvell.com>
Cc: stable@kernel.org
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2009-11-30 13:55:51 -05:00

168 lines
5.2 KiB
C

/*
* HT handling
*
* Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
* Copyright 2002-2005, Instant802 Networks, Inc.
* Copyright 2005-2006, Devicescape Software, Inc.
* Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
* Copyright 2007, Michael Wu <flamingice@sourmilk.net>
* Copyright 2007-2008, Intel Corporation
*
* 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 <linux/ieee80211.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "rate.h"
void ieee80211_ht_cap_ie_to_sta_ht_cap(struct ieee80211_supported_band *sband,
struct ieee80211_ht_cap *ht_cap_ie,
struct ieee80211_sta_ht_cap *ht_cap)
{
u8 ampdu_info, tx_mcs_set_cap;
int i, max_tx_streams;
BUG_ON(!ht_cap);
memset(ht_cap, 0, sizeof(*ht_cap));
if (!ht_cap_ie)
return;
ht_cap->ht_supported = true;
ht_cap->cap = le16_to_cpu(ht_cap_ie->cap_info) & sband->ht_cap.cap;
ht_cap->cap &= ~IEEE80211_HT_CAP_SM_PS;
ht_cap->cap |= sband->ht_cap.cap & IEEE80211_HT_CAP_SM_PS;
ampdu_info = ht_cap_ie->ampdu_params_info;
ht_cap->ampdu_factor =
ampdu_info & IEEE80211_HT_AMPDU_PARM_FACTOR;
ht_cap->ampdu_density =
(ampdu_info & IEEE80211_HT_AMPDU_PARM_DENSITY) >> 2;
/* own MCS TX capabilities */
tx_mcs_set_cap = sband->ht_cap.mcs.tx_params;
/* can we TX with MCS rates? */
if (!(tx_mcs_set_cap & IEEE80211_HT_MCS_TX_DEFINED))
return;
/* Counting from 0, therefore +1 */
if (tx_mcs_set_cap & IEEE80211_HT_MCS_TX_RX_DIFF)
max_tx_streams =
((tx_mcs_set_cap & IEEE80211_HT_MCS_TX_MAX_STREAMS_MASK)
>> IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT) + 1;
else
max_tx_streams = IEEE80211_HT_MCS_TX_MAX_STREAMS;
/*
* 802.11n D5.0 20.3.5 / 20.6 says:
* - indices 0 to 7 and 32 are single spatial stream
* - 8 to 31 are multiple spatial streams using equal modulation
* [8..15 for two streams, 16..23 for three and 24..31 for four]
* - remainder are multiple spatial streams using unequal modulation
*/
for (i = 0; i < max_tx_streams; i++)
ht_cap->mcs.rx_mask[i] =
sband->ht_cap.mcs.rx_mask[i] & ht_cap_ie->mcs.rx_mask[i];
if (tx_mcs_set_cap & IEEE80211_HT_MCS_TX_UNEQUAL_MODULATION)
for (i = IEEE80211_HT_MCS_UNEQUAL_MODULATION_START_BYTE;
i < IEEE80211_HT_MCS_MASK_LEN; i++)
ht_cap->mcs.rx_mask[i] =
sband->ht_cap.mcs.rx_mask[i] &
ht_cap_ie->mcs.rx_mask[i];
/* handle MCS rate 32 too */
if (sband->ht_cap.mcs.rx_mask[32/8] & ht_cap_ie->mcs.rx_mask[32/8] & 1)
ht_cap->mcs.rx_mask[32/8] |= 1;
}
void ieee80211_sta_tear_down_BA_sessions(struct sta_info *sta)
{
int i;
for (i = 0; i < STA_TID_NUM; i++) {
__ieee80211_stop_tx_ba_session(sta, i, WLAN_BACK_INITIATOR);
__ieee80211_stop_rx_ba_session(sta, i, WLAN_BACK_RECIPIENT,
WLAN_REASON_QSTA_LEAVE_QBSS);
}
}
void ieee80211_send_delba(struct ieee80211_sub_if_data *sdata,
const u8 *da, u16 tid,
u16 initiator, u16 reason_code)
{
struct ieee80211_local *local = sdata->local;
struct sk_buff *skb;
struct ieee80211_mgmt *mgmt;
u16 params;
skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
if (!skb) {
printk(KERN_ERR "%s: failed to allocate buffer "
"for delba frame\n", sdata->dev->name);
return;
}
skb_reserve(skb, local->hw.extra_tx_headroom);
mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
memset(mgmt, 0, 24);
memcpy(mgmt->da, da, ETH_ALEN);
memcpy(mgmt->sa, sdata->dev->dev_addr, ETH_ALEN);
if (sdata->vif.type == NL80211_IFTYPE_AP ||
sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
memcpy(mgmt->bssid, sdata->dev->dev_addr, ETH_ALEN);
else if (sdata->vif.type == NL80211_IFTYPE_STATION)
memcpy(mgmt->bssid, sdata->u.mgd.bssid, ETH_ALEN);
mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
IEEE80211_STYPE_ACTION);
skb_put(skb, 1 + sizeof(mgmt->u.action.u.delba));
mgmt->u.action.category = WLAN_CATEGORY_BACK;
mgmt->u.action.u.delba.action_code = WLAN_ACTION_DELBA;
params = (u16)(initiator << 11); /* bit 11 initiator */
params |= (u16)(tid << 12); /* bit 15:12 TID number */
mgmt->u.action.u.delba.params = cpu_to_le16(params);
mgmt->u.action.u.delba.reason_code = cpu_to_le16(reason_code);
ieee80211_tx_skb(sdata, skb, 1);
}
void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata,
struct sta_info *sta,
struct ieee80211_mgmt *mgmt, size_t len)
{
u16 tid, params;
u16 initiator;
params = le16_to_cpu(mgmt->u.action.u.delba.params);
tid = (params & IEEE80211_DELBA_PARAM_TID_MASK) >> 12;
initiator = (params & IEEE80211_DELBA_PARAM_INITIATOR_MASK) >> 11;
#ifdef CONFIG_MAC80211_HT_DEBUG
if (net_ratelimit())
printk(KERN_DEBUG "delba from %pM (%s) tid %d reason code %d\n",
mgmt->sa, initiator ? "initiator" : "recipient", tid,
le16_to_cpu(mgmt->u.action.u.delba.reason_code));
#endif /* CONFIG_MAC80211_HT_DEBUG */
if (initiator == WLAN_BACK_INITIATOR)
ieee80211_sta_stop_rx_ba_session(sdata, sta->sta.addr, tid,
WLAN_BACK_INITIATOR, 0);
else { /* WLAN_BACK_RECIPIENT */
spin_lock_bh(&sta->lock);
if (sta->ampdu_mlme.tid_state_tx[tid] & HT_ADDBA_REQUESTED_MSK)
___ieee80211_stop_tx_ba_session(sta, tid,
WLAN_BACK_RECIPIENT);
spin_unlock_bh(&sta->lock);
}
}