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linux/net/mac80211/sta_info.c
Johannes Berg db4d1169d0 mac80211: split ieee80211_key_alloc/free 
In order to RCU-ify sta_info, we need to be able to allocate
a key without linking it to an sdata/sta structure (because
allocation cannot be done in an rcu critical section). This
patch splits up ieee80211_key_alloc() and updates all users
appropriately.

While at it, this patch fixes a number of race conditions
such as finally making key replacement atomic, unfortunately
at the expense of more complex code.

Note that this patch documents /existing/ bugs with sta info
and key interaction, there is currently a race condition
when a sta info is freed without holding the RTNL. This will
finally be fixed by a followup patch.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-02-29 15:42:04 -05:00

490 lines
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/*
* Copyright 2002-2005, Instant802 Networks, Inc.
* Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
*
* 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/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/timer.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "ieee80211_rate.h"
#include "sta_info.h"
#include "debugfs_sta.h"
/* Caller must hold local->sta_lock */
static void sta_info_hash_add(struct ieee80211_local *local,
struct sta_info *sta)
{
sta->hnext = local->sta_hash[STA_HASH(sta->addr)];
local->sta_hash[STA_HASH(sta->addr)] = sta;
}
/* Caller must hold local->sta_lock */
static int sta_info_hash_del(struct ieee80211_local *local,
struct sta_info *sta)
{
struct sta_info *s;
s = local->sta_hash[STA_HASH(sta->addr)];
if (!s)
return -ENOENT;
if (s == sta) {
local->sta_hash[STA_HASH(sta->addr)] = s->hnext;
return 0;
}
while (s->hnext && s->hnext != sta)
s = s->hnext;
if (s->hnext) {
s->hnext = sta->hnext;
return 0;
}
return -ENOENT;
}
/* must hold local->sta_lock */
static struct sta_info *__sta_info_find(struct ieee80211_local *local,
u8 *addr)
{
struct sta_info *sta;
sta = local->sta_hash[STA_HASH(addr)];
while (sta) {
if (compare_ether_addr(sta->addr, addr) == 0)
break;
sta = sta->hnext;
}
return sta;
}
struct sta_info *sta_info_get(struct ieee80211_local *local, u8 *addr)
{
struct sta_info *sta;
read_lock_bh(&local->sta_lock);
sta = __sta_info_find(local, addr);
if (sta)
__sta_info_get(sta);
read_unlock_bh(&local->sta_lock);
return sta;
}
EXPORT_SYMBOL(sta_info_get);
static void sta_info_release(struct kref *kref)
{
struct sta_info *sta = container_of(kref, struct sta_info, kref);
struct ieee80211_local *local = sta->local;
struct sk_buff *skb;
int i;
/* free sta structure; it has already been removed from
* hash table etc. external structures. Make sure that all
* buffered frames are release (one might have been added
* after sta_info_free() was called). */
while ((skb = skb_dequeue(&sta->ps_tx_buf)) != NULL) {
local->total_ps_buffered--;
dev_kfree_skb_any(skb);
}
while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL) {
dev_kfree_skb_any(skb);
}
for (i = 0; i < STA_TID_NUM; i++) {
del_timer_sync(&sta->ampdu_mlme.tid_rx[i].session_timer);
del_timer_sync(&sta->ampdu_mlme.tid_tx[i].addba_resp_timer);
}
rate_control_free_sta(sta->rate_ctrl, sta->rate_ctrl_priv);
rate_control_put(sta->rate_ctrl);
kfree(sta);
}
void sta_info_put(struct sta_info *sta)
{
kref_put(&sta->kref, sta_info_release);
}
EXPORT_SYMBOL(sta_info_put);
struct sta_info *sta_info_add(struct ieee80211_local *local,
struct net_device *dev, u8 *addr, gfp_t gfp)
{
struct sta_info *sta;
int i;
DECLARE_MAC_BUF(mac);
sta = kzalloc(sizeof(*sta), gfp);
if (!sta)
return ERR_PTR(-ENOMEM);
kref_init(&sta->kref);
sta->rate_ctrl = rate_control_get(local->rate_ctrl);
sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl, gfp);
if (!sta->rate_ctrl_priv) {
rate_control_put(sta->rate_ctrl);
kfree(sta);
return ERR_PTR(-ENOMEM);
}
memcpy(sta->addr, addr, ETH_ALEN);
sta->local = local;
sta->dev = dev;
spin_lock_init(&sta->ampdu_mlme.ampdu_rx);
spin_lock_init(&sta->ampdu_mlme.ampdu_tx);
for (i = 0; i < STA_TID_NUM; i++) {
/* timer_to_tid must be initialized with identity mapping to
* enable session_timer's data differentiation. refer to
* sta_rx_agg_session_timer_expired for useage */
sta->timer_to_tid[i] = i;
/* tid to tx queue: initialize according to HW (0 is valid) */
sta->tid_to_tx_q[i] = local->hw.queues;
/* rx timers */
sta->ampdu_mlme.tid_rx[i].session_timer.function =
sta_rx_agg_session_timer_expired;
sta->ampdu_mlme.tid_rx[i].session_timer.data =
(unsigned long)&sta->timer_to_tid[i];
init_timer(&sta->ampdu_mlme.tid_rx[i].session_timer);
/* tx timers */
sta->ampdu_mlme.tid_tx[i].addba_resp_timer.function =
sta_addba_resp_timer_expired;
sta->ampdu_mlme.tid_tx[i].addba_resp_timer.data =
(unsigned long)&sta->timer_to_tid[i];
init_timer(&sta->ampdu_mlme.tid_tx[i].addba_resp_timer);
}
skb_queue_head_init(&sta->ps_tx_buf);
skb_queue_head_init(&sta->tx_filtered);
write_lock_bh(&local->sta_lock);
/* mark sta as used (by caller) */
__sta_info_get(sta);
/* check if STA exists already */
if (__sta_info_find(local, addr)) {
write_unlock_bh(&local->sta_lock);
sta_info_put(sta);
return ERR_PTR(-EEXIST);
}
list_add(&sta->list, &local->sta_list);
local->num_sta++;
sta_info_hash_add(local, sta);
if (local->ops->sta_notify) {
struct ieee80211_sub_if_data *sdata;
sdata = IEEE80211_DEV_TO_SUB_IF(dev);
if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN)
sdata = sdata->u.vlan.ap;
local->ops->sta_notify(local_to_hw(local), &sdata->vif,
STA_NOTIFY_ADD, addr);
}
write_unlock_bh(&local->sta_lock);
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
printk(KERN_DEBUG "%s: Added STA %s\n",
wiphy_name(local->hw.wiphy), print_mac(mac, addr));
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
#ifdef CONFIG_MAC80211_DEBUGFS
/* debugfs entry adding might sleep, so schedule process
* context task for adding entry for STAs that do not yet
* have one. */
queue_work(local->hw.workqueue, &local->sta_debugfs_add);
#endif
return sta;
}
static inline void __bss_tim_set(struct ieee80211_if_ap *bss, u16 aid)
{
/*
* This format has been mandated by the IEEE specifications,
* so this line may not be changed to use the __set_bit() format.
*/
bss->tim[aid / 8] |= (1 << (aid % 8));
}
static inline void __bss_tim_clear(struct ieee80211_if_ap *bss, u16 aid)
{
/*
* This format has been mandated by the IEEE specifications,
* so this line may not be changed to use the __clear_bit() format.
*/
bss->tim[aid / 8] &= ~(1 << (aid % 8));
}
static void __sta_info_set_tim_bit(struct ieee80211_if_ap *bss,
struct sta_info *sta)
{
if (bss)
__bss_tim_set(bss, sta->aid);
if (sta->local->ops->set_tim)
sta->local->ops->set_tim(local_to_hw(sta->local), sta->aid, 1);
}
void sta_info_set_tim_bit(struct sta_info *sta)
{
struct ieee80211_sub_if_data *sdata;
sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
read_lock_bh(&sta->local->sta_lock);
__sta_info_set_tim_bit(sdata->bss, sta);
read_unlock_bh(&sta->local->sta_lock);
}
static void __sta_info_clear_tim_bit(struct ieee80211_if_ap *bss,
struct sta_info *sta)
{
if (bss)
__bss_tim_clear(bss, sta->aid);
if (sta->local->ops->set_tim)
sta->local->ops->set_tim(local_to_hw(sta->local), sta->aid, 0);
}
void sta_info_clear_tim_bit(struct sta_info *sta)
{
struct ieee80211_sub_if_data *sdata;
sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
read_lock_bh(&sta->local->sta_lock);
__sta_info_clear_tim_bit(sdata->bss, sta);
read_unlock_bh(&sta->local->sta_lock);
}
/* Caller must hold local->sta_lock */
void sta_info_remove(struct sta_info *sta)
{
struct ieee80211_local *local = sta->local;
struct ieee80211_sub_if_data *sdata;
/* don't do anything if we've been removed already */
if (sta_info_hash_del(local, sta))
return;
list_del(&sta->list);
sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
if (sta->flags & WLAN_STA_PS) {
sta->flags &= ~WLAN_STA_PS;
if (sdata->bss)
atomic_dec(&sdata->bss->num_sta_ps);
__sta_info_clear_tim_bit(sdata->bss, sta);
}
local->num_sta--;
}
void sta_info_free(struct sta_info *sta)
{
struct sk_buff *skb;
struct ieee80211_local *local = sta->local;
DECLARE_MAC_BUF(mac);
might_sleep();
write_lock_bh(&local->sta_lock);
sta_info_remove(sta);
write_unlock_bh(&local->sta_lock);
while ((skb = skb_dequeue(&sta->ps_tx_buf)) != NULL) {
local->total_ps_buffered--;
dev_kfree_skb(skb);
}
while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL) {
dev_kfree_skb(skb);
}
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
printk(KERN_DEBUG "%s: Removed STA %s\n",
wiphy_name(local->hw.wiphy), print_mac(mac, sta->addr));
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
ieee80211_key_free(sta->key);
WARN_ON(sta->key);
if (local->ops->sta_notify) {
struct ieee80211_sub_if_data *sdata;
sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN)
sdata = sdata->u.vlan.ap;
local->ops->sta_notify(local_to_hw(local), &sdata->vif,
STA_NOTIFY_REMOVE, sta->addr);
}
rate_control_remove_sta_debugfs(sta);
ieee80211_sta_debugfs_remove(sta);
sta_info_put(sta);
}
static inline int sta_info_buffer_expired(struct ieee80211_local *local,
struct sta_info *sta,
struct sk_buff *skb)
{
struct ieee80211_tx_packet_data *pkt_data;
int timeout;
if (!skb)
return 0;
pkt_data = (struct ieee80211_tx_packet_data *) skb->cb;
/* Timeout: (2 * listen_interval * beacon_int * 1024 / 1000000) sec */
timeout = (sta->listen_interval * local->hw.conf.beacon_int * 32 /
15625) * HZ;
if (timeout < STA_TX_BUFFER_EXPIRE)
timeout = STA_TX_BUFFER_EXPIRE;
return time_after(jiffies, pkt_data->jiffies + timeout);
}
static void sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
struct sta_info *sta)
{
unsigned long flags;
struct sk_buff *skb;
struct ieee80211_sub_if_data *sdata;
DECLARE_MAC_BUF(mac);
if (skb_queue_empty(&sta->ps_tx_buf))
return;
for (;;) {
spin_lock_irqsave(&sta->ps_tx_buf.lock, flags);
skb = skb_peek(&sta->ps_tx_buf);
if (sta_info_buffer_expired(local, sta, skb))
skb = __skb_dequeue(&sta->ps_tx_buf);
else
skb = NULL;
spin_unlock_irqrestore(&sta->ps_tx_buf.lock, flags);
if (!skb)
break;
sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
local->total_ps_buffered--;
printk(KERN_DEBUG "Buffered frame expired (STA "
"%s)\n", print_mac(mac, sta->addr));
dev_kfree_skb(skb);
if (skb_queue_empty(&sta->ps_tx_buf))
sta_info_clear_tim_bit(sta);
}
}
static void sta_info_cleanup(unsigned long data)
{
struct ieee80211_local *local = (struct ieee80211_local *) data;
struct sta_info *sta;
read_lock_bh(&local->sta_lock);
list_for_each_entry(sta, &local->sta_list, list) {
__sta_info_get(sta);
sta_info_cleanup_expire_buffered(local, sta);
sta_info_put(sta);
}
read_unlock_bh(&local->sta_lock);
local->sta_cleanup.expires =
round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);
add_timer(&local->sta_cleanup);
}
#ifdef CONFIG_MAC80211_DEBUGFS
static void sta_info_debugfs_add_task(struct work_struct *work)
{
struct ieee80211_local *local =
container_of(work, struct ieee80211_local, sta_debugfs_add);
struct sta_info *sta, *tmp;
while (1) {
sta = NULL;
read_lock_bh(&local->sta_lock);
list_for_each_entry(tmp, &local->sta_list, list) {
if (!tmp->debugfs.dir) {
sta = tmp;
__sta_info_get(sta);
break;
}
}
read_unlock_bh(&local->sta_lock);
if (!sta)
break;
ieee80211_sta_debugfs_add(sta);
rate_control_add_sta_debugfs(sta);
sta_info_put(sta);
}
}
#endif
void sta_info_init(struct ieee80211_local *local)
{
rwlock_init(&local->sta_lock);
INIT_LIST_HEAD(&local->sta_list);
setup_timer(&local->sta_cleanup, sta_info_cleanup,
(unsigned long)local);
local->sta_cleanup.expires =
round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);
#ifdef CONFIG_MAC80211_DEBUGFS
INIT_WORK(&local->sta_debugfs_add, sta_info_debugfs_add_task);
#endif
}
int sta_info_start(struct ieee80211_local *local)
{
add_timer(&local->sta_cleanup);
return 0;
}
void sta_info_stop(struct ieee80211_local *local)
{
del_timer(&local->sta_cleanup);
sta_info_flush(local, NULL);
}
/**
* sta_info_flush - flush matching STA entries from the STA table
* @local: local interface data
* @dev: matching rule for the net device (sta->dev) or %NULL to match all STAs
*/
void sta_info_flush(struct ieee80211_local *local, struct net_device *dev)
{
struct sta_info *sta, *tmp;
LIST_HEAD(tmp_list);
write_lock_bh(&local->sta_lock);
list_for_each_entry_safe(sta, tmp, &local->sta_list, list)
if (!dev || dev == sta->dev) {
__sta_info_get(sta);
sta_info_remove(sta);
list_add_tail(&sta->list, &tmp_list);
}
write_unlock_bh(&local->sta_lock);
list_for_each_entry_safe(sta, tmp, &tmp_list, list) {
sta_info_free(sta);
sta_info_put(sta);
}
}
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