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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>
This commit is contained in:
Johannes Berg 2008-02-25 16:27:45 +01:00 committed by John W. Linville
parent 6f48422a29
commit db4d1169d0
5 changed files with 209 additions and 104 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
net/mac80211/cfg.c
View File

@ -123,6 +123,7 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
struct sta_info *sta = NULL;
enum ieee80211_key_alg alg;
int ret;
struct ieee80211_key *key;
sdata = IEEE80211_DEV_TO_SUB_IF(dev);
@ -141,16 +142,21 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
return -EINVAL;
}
key = ieee80211_key_alloc(alg, key_idx, params->key_len, params->key);
if (!key)
return -ENOMEM;
if (mac_addr) {
sta = sta_info_get(sdata->local, mac_addr);
if (!sta)
if (!sta) {
ieee80211_key_free(key);
return -ENOENT;
}
}
ieee80211_key_link(key, sdata, sta);
ret = 0;
if (!ieee80211_key_alloc(sdata, sta, alg, key_idx,
params->key_len, params->key))
ret = -ENOMEM;
if (sta)
sta_info_put(sta);
@ -164,6 +170,7 @@ static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
struct ieee80211_sub_if_data *sdata;
struct sta_info *sta;
int ret;
struct ieee80211_key *key;
sdata = IEEE80211_DEV_TO_SUB_IF(dev);
@ -173,9 +180,11 @@ static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
return -ENOENT;
ret = 0;
if (sta->key)
ieee80211_key_free(sta->key);
else
if (sta->key) {
key = sta->key;
ieee80211_key_free(key);
WARN_ON(sta->key);
} else
ret = -ENOENT;
sta_info_put(sta);
@ -185,7 +194,9 @@ static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
if (!sdata->keys[key_idx])
return -ENOENT;
ieee80211_key_free(sdata->keys[key_idx]);
key = sdata->keys[key_idx];
ieee80211_key_free(key);
WARN_ON(sdata->keys[key_idx]);
return 0;
}

100
net/mac80211/ieee80211_ioctl.c
View File

@ -33,8 +33,8 @@ static int ieee80211_set_encryption(struct net_device *dev, u8 *sta_addr,
size_t key_len)
{
struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
int ret = 0;
struct sta_info *sta;
int ret;
struct sta_info *sta = NULL;
struct ieee80211_key *key;
struct ieee80211_sub_if_data *sdata;
@ -46,58 +46,64 @@ static int ieee80211_set_encryption(struct net_device *dev, u8 *sta_addr,
return -EINVAL;
}
if (is_broadcast_ether_addr(sta_addr)) {
sta = NULL;
key = sdata->keys[idx];
} else {
set_tx_key = 0;
/*
* According to the standard, the key index of a pairwise
* key must be zero. However, some AP are broken when it
* comes to WEP key indices, so we work around this.
*/
if (idx != 0 && alg != ALG_WEP) {
printk(KERN_DEBUG "%s: set_encrypt - non-zero idx for "
"individual key\n", dev->name);
return -EINVAL;
}
sta = sta_info_get(local, sta_addr);
if (!sta) {
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
DECLARE_MAC_BUF(mac);
printk(KERN_DEBUG "%s: set_encrypt - unknown addr "
"%s\n",
dev->name, print_mac(mac, sta_addr));
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
return -ENOENT;
}
key = sta->key;
}
if (remove) {
ieee80211_key_free(key);
key = NULL;
} else {
/*
* Automatically frees any old key if present.
*/
key = ieee80211_key_alloc(sdata, sta, alg, idx, key_len, _key);
if (!key) {
ret = -ENOMEM;
goto err_out;
if (is_broadcast_ether_addr(sta_addr)) {
key = sdata->keys[idx];
} else {
sta = sta_info_get(local, sta_addr);
if (!sta) {
ret = -ENOENT;
key = NULL;
goto err_out;
}
key = sta->key;
}
if (!key)
ret = -ENOENT;
else
ret = 0;
} else {
key = ieee80211_key_alloc(alg, idx, key_len, _key);
if (!key)
return -ENOMEM;
if (!is_broadcast_ether_addr(sta_addr)) {
set_tx_key = 0;
/*
* According to the standard, the key index of a
* pairwise key must be zero. However, some AP are
* broken when it comes to WEP key indices, so we
* work around this.
*/
if (idx != 0 && alg != ALG_WEP) {
ret = -EINVAL;
goto err_out;
}
sta = sta_info_get(local, sta_addr);
if (!sta) {
ret = -ENOENT;
goto err_out;
}
}
ieee80211_key_link(key, sdata, sta);
if (set_tx_key || (!sta && !sdata->default_key && key))
ieee80211_set_default_key(sdata, idx);
/* don't free key later */
key = NULL;
ret = 0;
}
if (set_tx_key || (!sta && !sdata->default_key && key))
ieee80211_set_default_key(sdata, idx);
ret = 0;
err_out:
if (sta)
sta_info_put(sta);
ieee80211_key_free(key);
return ret;
}

26
net/mac80211/ieee80211_key.h
View File

@ -13,6 +13,7 @@
#include <linux/types.h>
#include <linux/list.h>
#include <linux/crypto.h>
#include <linux/rcupdate.h>
#include <net/mac80211.h>
/* ALG_TKIP
@ -45,7 +46,19 @@ struct ieee80211_local;
struct ieee80211_sub_if_data;
struct sta_info;
#define KEY_FLAG_UPLOADED_TO_HARDWARE (1<<0)
/**
* enum ieee80211_internal_key_flags - internal key flags
*
* @KEY_FLAG_UPLOADED_TO_HARDWARE: Indicates that this key is present
* in the hardware for TX crypto hardware acceleration.
* @KEY_FLAG_REMOVE_FROM_HARDWARE: Indicates to the key code that this
* key is present in the hardware (but it cannot be used for
* hardware acceleration any more!)
*/
enum ieee80211_internal_key_flags {
KEY_FLAG_UPLOADED_TO_HARDWARE = BIT(0),
KEY_FLAG_REMOVE_FROM_HARDWARE = BIT(1),
};
struct ieee80211_key {
struct ieee80211_local *local;
@ -112,12 +125,17 @@ struct ieee80211_key {
struct ieee80211_key_conf conf;
};
struct ieee80211_key *ieee80211_key_alloc(struct ieee80211_sub_if_data *sdata,
struct sta_info *sta,
enum ieee80211_key_alg alg,
struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
int idx,
size_t key_len,
const u8 *key_data);
/*
* Insert a key into data structures (sdata, sta if necessary)
* to make it used, free old key.
*/
void ieee80211_key_link(struct ieee80211_key *key,
struct ieee80211_sub_if_data *sdata,
struct sta_info *sta);
void ieee80211_key_free(struct ieee80211_key *key);
void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx);
void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata);

158
net/mac80211/key.c
View File

@ -13,6 +13,7 @@
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/rtnetlink.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "debugfs_key.h"
@ -34,6 +35,10 @@
*
* All operations here are called under RTNL so no extra locking is
* required.
*
* NOTE: This code requires that sta info *destruction* is done under
* RTNL, otherwise it can try to access already freed STA structs
* when a STA key is being freed.
*/
static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
@ -84,16 +89,25 @@ static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
key->conf.keyidx, print_mac(mac, addr), ret);
}
static void ieee80211_key_mark_hw_accel_off(struct ieee80211_key *key)
{
if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
key->flags |= KEY_FLAG_REMOVE_FROM_HARDWARE;
}
}
static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
{
const u8 *addr;
int ret;
DECLARE_MAC_BUF(mac);
if (!key->local->ops->set_key)
if (!key || !key->local->ops->set_key)
return;
if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
!(key->flags & KEY_FLAG_REMOVE_FROM_HARDWARE))
return;
addr = get_mac_for_key(key);
@ -108,12 +122,11 @@ static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
wiphy_name(key->local->hw.wiphy),
key->conf.keyidx, print_mac(mac, addr), ret);
key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
key->flags &= ~(KEY_FLAG_UPLOADED_TO_HARDWARE |
KEY_FLAG_REMOVE_FROM_HARDWARE);
}
struct ieee80211_key *ieee80211_key_alloc(struct ieee80211_sub_if_data *sdata,
struct sta_info *sta,
enum ieee80211_key_alg alg,
struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
int idx,
size_t key_len,
const u8 *key_data)
@ -138,10 +151,6 @@ struct ieee80211_key *ieee80211_key_alloc(struct ieee80211_sub_if_data *sdata,
key->conf.keylen = key_len;
memcpy(key->conf.key, key_data, key_len);
key->local = sdata->local;
key->sdata = sdata;
key->sta = sta;
if (alg == ALG_CCMP) {
/*
* Initialize AES key state here as an optimization so that
@ -154,13 +163,62 @@ struct ieee80211_key *ieee80211_key_alloc(struct ieee80211_sub_if_data *sdata,
}
}
ieee80211_debugfs_key_add(key->local, key);
return key;
}
/* remove key first */
if (sta)
ieee80211_key_free(sta->key);
else
ieee80211_key_free(sdata->keys[idx]);
static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
struct sta_info *sta,
struct ieee80211_key *key,
struct ieee80211_key *new)
{
int idx, defkey;
if (sta) {
rcu_assign_pointer(sta->key, new);
} else {
WARN_ON(new && key && new->conf.keyidx != key->conf.keyidx);
if (key)
idx = key->conf.keyidx;
else
idx = new->conf.keyidx;
defkey = key && sdata->default_key == key;
if (defkey && !new)
ieee80211_set_default_key(sdata, -1);
rcu_assign_pointer(sdata->keys[idx], new);
if (defkey && new)
ieee80211_set_default_key(sdata, new->conf.keyidx);
}
if (key) {
ieee80211_key_mark_hw_accel_off(key);
list_del(&key->list);
}
}
void ieee80211_key_link(struct ieee80211_key *key,
struct ieee80211_sub_if_data *sdata,
struct sta_info *sta)
{
struct ieee80211_key *old_key;
int idx;
ASSERT_RTNL();
might_sleep();
BUG_ON(!sdata);
BUG_ON(!key);
idx = key->conf.keyidx;
key->local = sdata->local;
key->sdata = sdata;
key->sta = sta;
ieee80211_debugfs_key_add(key->local, key);
if (sta) {
ieee80211_debugfs_key_sta_link(key, sta);
@ -186,50 +244,53 @@ struct ieee80211_key *ieee80211_key_alloc(struct ieee80211_sub_if_data *sdata,
}
}
/* enable hwaccel if appropriate */
if (netif_running(key->sdata->dev))
ieee80211_key_enable_hw_accel(key);
if (sta)
rcu_assign_pointer(sta->key, key);
old_key = sta->key;
else
rcu_assign_pointer(sdata->keys[idx], key);
old_key = sdata->keys[idx];
__ieee80211_key_replace(sdata, sta, old_key, key);
list_add(&key->list, &sdata->key_list);
return key;
synchronize_rcu();
ieee80211_key_free(old_key);
ieee80211_key_enable_hw_accel(key);
}
void ieee80211_key_free(struct ieee80211_key *key)
{
ASSERT_RTNL();
might_sleep();
if (!key)
return;
if (key->sta) {
rcu_assign_pointer(key->sta->key, NULL);
} else {
if (key->sdata->default_key == key)
ieee80211_set_default_key(key->sdata, -1);
if (key->conf.keyidx >= 0 &&
key->conf.keyidx < NUM_DEFAULT_KEYS)
rcu_assign_pointer(key->sdata->keys[key->conf.keyidx],
NULL);
else
WARN_ON(1);
if (key->sdata) {
/*
* Replace key with nothingness.
*
* Because other code may have key reference (RCU protected)
* right now, we then wait for a grace period before freeing
* it.
*/
__ieee80211_key_replace(key->sdata, key->sta, key, NULL);
synchronize_rcu();
/*
* Remove from hwaccel if appropriate, this will
* only happen when the key is actually unlinked,
* it will already be done when the key was replaced.
*/
ieee80211_key_disable_hw_accel(key);
}
/* wait for all key users to complete */
synchronize_rcu();
/* remove from hwaccel if appropriate */
ieee80211_key_disable_hw_accel(key);
if (key->conf.alg == ALG_CCMP)
ieee80211_aes_key_free(key->u.ccmp.tfm);
ieee80211_debugfs_key_remove(key);
list_del(&key->list);
kfree(key);
}
@ -253,6 +314,10 @@ void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_key *key, *tmp;
LIST_HEAD(tmp_list);
ASSERT_RTNL();
might_sleep();
list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
ieee80211_key_free(key);
@ -262,8 +327,10 @@ void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_key *key;
WARN_ON(!netif_running(sdata->dev));
if (!netif_running(sdata->dev))
ASSERT_RTNL();
might_sleep();
if (WARN_ON(!netif_running(sdata->dev)))
return;
list_for_each_entry(key, &sdata->key_list, list)
@ -274,6 +341,9 @@ void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_key *key;
ASSERT_RTNL();
might_sleep();
list_for_each_entry(key, &sdata->key_list, list)
ieee80211_key_disable_hw_accel(key);
}

2
net/mac80211/sta_info.c
View File

@ -312,7 +312,7 @@ void sta_info_free(struct sta_info *sta)
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
ieee80211_key_free(sta->key);
sta->key = NULL;
WARN_ON(sta->key);
if (local->ops->sta_notify) {
struct ieee80211_sub_if_data *sdata;