From: Johannes Berg Date: Mon, 25 Feb 2008 15:27:45 +0000 (+0100) Subject: mac80211: split ieee80211_key_alloc/free X-Git-Tag: v2.6.26-rc1~1138^2~530^2~1 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=db4d1169d0b893bfb7923b6526748fe2c5a7373f;p=linux-2.6 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 Signed-off-by: John W. Linville --- diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c index b0c41a0cee..e7535ffc8e 100644 --- a/net/mac80211/cfg.c +++ b/net/mac80211/cfg.c @@ -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; } diff --git a/net/mac80211/ieee80211_ioctl.c b/net/mac80211/ieee80211_ioctl.c index 54ad07aafe..7551db3f3a 100644 --- a/net/mac80211/ieee80211_ioctl.c +++ b/net/mac80211/ieee80211_ioctl.c @@ -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; + if (remove) { + 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; } - 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 */ + 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; + } - return -ENOENT; + sta = sta_info_get(local, sta_addr); + if (!sta) { + ret = -ENOENT; + goto err_out; + } } - key = sta->key; - } + ieee80211_key_link(key, sdata, sta); - if (remove) { - ieee80211_key_free(key); + if (set_tx_key || (!sta && !sdata->default_key && key)) + ieee80211_set_default_key(sdata, idx); + + /* don't free key later */ 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 (set_tx_key || (!sta && !sdata->default_key && key)) - ieee80211_set_default_key(sdata, idx); + ret = 0; + } - 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 fc770e98d4..d670e6dbfa 100644 --- a/net/mac80211/ieee80211_key.h +++ b/net/mac80211/ieee80211_key.h @@ -13,6 +13,7 @@ #include #include #include +#include #include /* 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); diff --git a/net/mac80211/key.c b/net/mac80211/key.c index ed57fb8e82..60aaaf4715 100644 --- a/net/mac80211/key.c +++ b/net/mac80211/key.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #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); - /* wait for all key users to complete */ - synchronize_rcu(); + synchronize_rcu(); - /* remove from hwaccel if appropriate */ - ieee80211_key_disable_hw_accel(key); + /* + * 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); } diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c index c6c0df4bbd..e384e6632d 100644 --- a/net/mac80211/sta_info.c +++ b/net/mac80211/sta_info.c @@ -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;