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>
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index b0c41a0..e7535ff 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -123,6 +123,7 @@
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 @@
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 @@
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 @@
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 @@
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;
}
diff --git a/net/mac80211/ieee80211_ioctl.c b/net/mac80211/ieee80211_ioctl.c
index 54ad07a..7551db3 100644
--- a/net/mac80211/ieee80211_ioctl.c
+++ b/net/mac80211/ieee80211_ioctl.c
@@ -33,8 +33,8 @@
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 @@
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;
}
diff --git a/net/mac80211/ieee80211_key.h b/net/mac80211/ieee80211_key.h
index fc770e9..d670e6d 100644
--- a/net/mac80211/ieee80211_key.h
+++ b/net/mac80211/ieee80211_key.h
@@ -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_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_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);
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index ed57fb8..60aaaf4 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -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 @@
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 @@
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 @@
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 @@
}
}
- 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 @@
}
}
- /* 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_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 @@
{
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 @@
{
struct ieee80211_key *key;
+ ASSERT_RTNL();
+ might_sleep();
+
list_for_each_entry(key, &sdata->key_list, list)
ieee80211_key_disable_hw_accel(key);
}
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index c6c0df4..e384e66 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -312,7 +312,7 @@
#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;