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Commit db4d1169 authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
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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: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 6f48422a

net/mac80211/cfg.c

+19 −8
Original line number Diff line number Diff line
@@ -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;

}

net/mac80211/ieee80211_ioctl.c

+48 −42
Original line number Diff line number Diff line
@@ -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 (remove) {

		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;

				ret = -ENOENT;

				key = NULL;

				goto err_out;

			}



			key = sta->key;

		}



	if (remove) {

		ieee80211_key_free(key);

		key = NULL;

		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;

			/*

		 * Automatically frees any old key if present.

			 * 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.

			 */

		key = ieee80211_key_alloc(sdata, sta, alg, idx, key_len, _key);

		if (!key) {

			ret = -ENOMEM;

			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;

	}



 err_out:

	if (sta)

		sta_info_put(sta);

	ieee80211_key_free(key);

	return ret;

}

net/mac80211/ieee80211_key.h

+22 −4
Original line number Diff line number Diff line
@@ -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);

net/mac80211/key.c

+113 −43
Original line number Diff line number Diff line
@@ -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);

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

		ieee80211_key_free(sdata->keys[idx]);

			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);



	/* wait for all key users to complete */

		synchronize_rcu();



	/* remove from hwaccel if appropriate */

		/*

		 * 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);

	}



	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);

}

net/mac80211/sta_info.c

+1 −1
Original line number Diff line number Diff line
@@ -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;