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![Jouni Malinen](/assets/img/avatar_default.png)
Key locking simplification removed key->sdata != NULL verification from ieee80211_key_free(). While that is fine for most use cases, there is one path where this function can be called with an unlinked key (i.e., key->sdata == NULL && key->local == NULL). This results in a NULL pointer dereference with the current implementation. This is known to happen at least with FT protocol when wpa_supplicant tries to configure the key before association. Avoid the issue by passing in the local pointer to ieee80211_key_free(). In addition, do not clear the key from hw_accel or debugfs if it has not yet been added. At least the hw_accel one could trigger another NULL pointer dereference. Signed-off-by: Jouni Malinen <j@w1.fi> Reviewed-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
470 lines
11 KiB
C
470 lines
11 KiB
C
/*
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* Copyright 2002-2005, Instant802 Networks, Inc.
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* Copyright 2005-2006, Devicescape Software, Inc.
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* Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
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* Copyright 2007-2008 Johannes Berg <johannes@sipsolutions.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/if_ether.h>
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#include <linux/etherdevice.h>
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#include <linux/list.h>
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#include <linux/rcupdate.h>
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#include <linux/rtnetlink.h>
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#include <linux/slab.h>
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#include <net/mac80211.h>
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#include "ieee80211_i.h"
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#include "driver-ops.h"
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#include "debugfs_key.h"
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#include "aes_ccm.h"
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#include "aes_cmac.h"
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/**
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* DOC: Key handling basics
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*
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* Key handling in mac80211 is done based on per-interface (sub_if_data)
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* keys and per-station keys. Since each station belongs to an interface,
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* each station key also belongs to that interface.
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*
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* Hardware acceleration is done on a best-effort basis, for each key
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* that is eligible the hardware is asked to enable that key but if
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* it cannot do that they key is simply kept for software encryption.
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* There is currently no way of knowing this except by looking into
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* debugfs.
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*
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* All key operations are protected internally.
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*
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* Within mac80211, key references are, just as STA structure references,
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* protected by RCU. Note, however, that some things are unprotected,
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* namely the key->sta dereferences within the hardware acceleration
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* functions. This means that sta_info_destroy() must remove the key
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* which waits for an RCU grace period.
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*/
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static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
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static void assert_key_lock(struct ieee80211_local *local)
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{
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WARN_ON(!mutex_is_locked(&local->key_mtx));
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}
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static struct ieee80211_sta *get_sta_for_key(struct ieee80211_key *key)
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{
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if (key->sta)
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return &key->sta->sta;
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return NULL;
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}
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static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
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{
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struct ieee80211_sub_if_data *sdata;
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struct ieee80211_sta *sta;
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int ret;
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might_sleep();
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if (!key->local->ops->set_key)
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return;
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assert_key_lock(key->local);
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sta = get_sta_for_key(key);
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sdata = key->sdata;
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if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
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sdata = container_of(sdata->bss,
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struct ieee80211_sub_if_data,
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u.ap);
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ret = drv_set_key(key->local, SET_KEY, sdata, sta, &key->conf);
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if (!ret)
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key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
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if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
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printk(KERN_ERR "mac80211-%s: failed to set key "
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"(%d, %pM) to hardware (%d)\n",
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wiphy_name(key->local->hw.wiphy),
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key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
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}
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static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
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{
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struct ieee80211_sub_if_data *sdata;
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struct ieee80211_sta *sta;
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int ret;
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might_sleep();
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if (!key || !key->local->ops->set_key)
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return;
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assert_key_lock(key->local);
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if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
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return;
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sta = get_sta_for_key(key);
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sdata = key->sdata;
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if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
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sdata = container_of(sdata->bss,
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struct ieee80211_sub_if_data,
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u.ap);
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ret = drv_set_key(key->local, DISABLE_KEY, sdata,
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sta, &key->conf);
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if (ret)
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printk(KERN_ERR "mac80211-%s: failed to remove key "
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"(%d, %pM) from hardware (%d)\n",
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wiphy_name(key->local->hw.wiphy),
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key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
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key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
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}
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static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
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int idx)
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{
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struct ieee80211_key *key = NULL;
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assert_key_lock(sdata->local);
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if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
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key = sdata->keys[idx];
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rcu_assign_pointer(sdata->default_key, key);
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if (key) {
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ieee80211_debugfs_key_remove_default(key->sdata);
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ieee80211_debugfs_key_add_default(key->sdata);
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}
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}
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void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
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{
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mutex_lock(&sdata->local->key_mtx);
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__ieee80211_set_default_key(sdata, idx);
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mutex_unlock(&sdata->local->key_mtx);
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}
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static void
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__ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata, int idx)
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{
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struct ieee80211_key *key = NULL;
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assert_key_lock(sdata->local);
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if (idx >= NUM_DEFAULT_KEYS &&
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idx < NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
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key = sdata->keys[idx];
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rcu_assign_pointer(sdata->default_mgmt_key, key);
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if (key) {
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ieee80211_debugfs_key_remove_mgmt_default(key->sdata);
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ieee80211_debugfs_key_add_mgmt_default(key->sdata);
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}
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}
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void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
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int idx)
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{
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mutex_lock(&sdata->local->key_mtx);
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__ieee80211_set_default_mgmt_key(sdata, idx);
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mutex_unlock(&sdata->local->key_mtx);
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}
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static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
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struct sta_info *sta,
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struct ieee80211_key *old,
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struct ieee80211_key *new)
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{
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int idx, defkey, defmgmtkey;
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if (new)
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list_add(&new->list, &sdata->key_list);
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if (sta) {
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rcu_assign_pointer(sta->key, new);
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} else {
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WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);
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if (old)
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idx = old->conf.keyidx;
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else
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idx = new->conf.keyidx;
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defkey = old && sdata->default_key == old;
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defmgmtkey = old && sdata->default_mgmt_key == old;
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if (defkey && !new)
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__ieee80211_set_default_key(sdata, -1);
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if (defmgmtkey && !new)
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__ieee80211_set_default_mgmt_key(sdata, -1);
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rcu_assign_pointer(sdata->keys[idx], new);
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if (defkey && new)
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__ieee80211_set_default_key(sdata, new->conf.keyidx);
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if (defmgmtkey && new)
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__ieee80211_set_default_mgmt_key(sdata,
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new->conf.keyidx);
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}
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if (old) {
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/*
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* We'll use an empty list to indicate that the key
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* has already been removed.
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*/
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list_del_init(&old->list);
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}
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}
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struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
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int idx,
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size_t key_len,
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const u8 *key_data,
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size_t seq_len, const u8 *seq)
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{
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struct ieee80211_key *key;
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int i, j;
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BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS);
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key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
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if (!key)
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return NULL;
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/*
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* Default to software encryption; we'll later upload the
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* key to the hardware if possible.
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*/
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key->conf.flags = 0;
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key->flags = 0;
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key->conf.alg = alg;
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key->conf.keyidx = idx;
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key->conf.keylen = key_len;
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switch (alg) {
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case ALG_WEP:
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key->conf.iv_len = WEP_IV_LEN;
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key->conf.icv_len = WEP_ICV_LEN;
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break;
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case ALG_TKIP:
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key->conf.iv_len = TKIP_IV_LEN;
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key->conf.icv_len = TKIP_ICV_LEN;
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if (seq) {
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for (i = 0; i < NUM_RX_DATA_QUEUES; i++) {
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key->u.tkip.rx[i].iv32 =
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get_unaligned_le32(&seq[2]);
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key->u.tkip.rx[i].iv16 =
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get_unaligned_le16(seq);
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}
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}
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break;
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case ALG_CCMP:
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key->conf.iv_len = CCMP_HDR_LEN;
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key->conf.icv_len = CCMP_MIC_LEN;
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if (seq) {
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for (i = 0; i < NUM_RX_DATA_QUEUES + 1; i++)
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for (j = 0; j < CCMP_PN_LEN; j++)
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key->u.ccmp.rx_pn[i][j] =
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seq[CCMP_PN_LEN - j - 1];
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}
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break;
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case ALG_AES_CMAC:
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key->conf.iv_len = 0;
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key->conf.icv_len = sizeof(struct ieee80211_mmie);
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if (seq)
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for (j = 0; j < 6; j++)
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key->u.aes_cmac.rx_pn[j] = seq[6 - j - 1];
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break;
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}
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memcpy(key->conf.key, key_data, key_len);
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INIT_LIST_HEAD(&key->list);
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if (alg == ALG_CCMP) {
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/*
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* Initialize AES key state here as an optimization so that
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* it does not need to be initialized for every packet.
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*/
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key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
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if (!key->u.ccmp.tfm) {
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kfree(key);
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return NULL;
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}
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}
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if (alg == ALG_AES_CMAC) {
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/*
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* Initialize AES key state here as an optimization so that
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* it does not need to be initialized for every packet.
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*/
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key->u.aes_cmac.tfm =
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ieee80211_aes_cmac_key_setup(key_data);
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if (!key->u.aes_cmac.tfm) {
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kfree(key);
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return NULL;
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}
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}
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return key;
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}
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static void __ieee80211_key_destroy(struct ieee80211_key *key)
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{
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if (!key)
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return;
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if (key->local)
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ieee80211_key_disable_hw_accel(key);
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if (key->conf.alg == ALG_CCMP)
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ieee80211_aes_key_free(key->u.ccmp.tfm);
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if (key->conf.alg == ALG_AES_CMAC)
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ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
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if (key->local)
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ieee80211_debugfs_key_remove(key);
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kfree(key);
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}
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void ieee80211_key_link(struct ieee80211_key *key,
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struct ieee80211_sub_if_data *sdata,
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struct sta_info *sta)
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{
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struct ieee80211_key *old_key;
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int idx;
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BUG_ON(!sdata);
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BUG_ON(!key);
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idx = key->conf.keyidx;
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key->local = sdata->local;
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key->sdata = sdata;
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key->sta = sta;
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if (sta) {
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/*
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* some hardware cannot handle TKIP with QoS, so
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* we indicate whether QoS could be in use.
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*/
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if (test_sta_flags(sta, WLAN_STA_WME))
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key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
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/*
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* This key is for a specific sta interface,
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* inform the driver that it should try to store
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* this key as pairwise key.
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*/
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key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
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} else {
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if (sdata->vif.type == NL80211_IFTYPE_STATION) {
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struct sta_info *ap;
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/*
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* We're getting a sta pointer in,
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* so must be under RCU read lock.
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*/
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/* same here, the AP could be using QoS */
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ap = sta_info_get(key->sdata, key->sdata->u.mgd.bssid);
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if (ap) {
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if (test_sta_flags(ap, WLAN_STA_WME))
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key->conf.flags |=
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IEEE80211_KEY_FLAG_WMM_STA;
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}
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}
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}
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mutex_lock(&sdata->local->key_mtx);
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if (sta)
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old_key = sta->key;
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else
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old_key = sdata->keys[idx];
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__ieee80211_key_replace(sdata, sta, old_key, key);
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__ieee80211_key_destroy(old_key);
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ieee80211_debugfs_key_add(key);
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ieee80211_key_enable_hw_accel(key);
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mutex_unlock(&sdata->local->key_mtx);
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}
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static void __ieee80211_key_free(struct ieee80211_key *key)
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{
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/*
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* Replace key with nothingness if it was ever used.
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*/
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if (key->sdata)
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__ieee80211_key_replace(key->sdata, key->sta,
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key, NULL);
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__ieee80211_key_destroy(key);
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}
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void ieee80211_key_free(struct ieee80211_local *local,
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struct ieee80211_key *key)
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{
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if (!key)
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return;
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mutex_lock(&local->key_mtx);
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__ieee80211_key_free(key);
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mutex_unlock(&local->key_mtx);
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}
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void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
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{
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struct ieee80211_key *key;
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ASSERT_RTNL();
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if (WARN_ON(!ieee80211_sdata_running(sdata)))
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return;
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mutex_lock(&sdata->local->key_mtx);
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list_for_each_entry(key, &sdata->key_list, list)
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ieee80211_key_enable_hw_accel(key);
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mutex_unlock(&sdata->local->key_mtx);
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}
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void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
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{
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struct ieee80211_key *key;
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ASSERT_RTNL();
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mutex_lock(&sdata->local->key_mtx);
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list_for_each_entry(key, &sdata->key_list, list)
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ieee80211_key_disable_hw_accel(key);
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mutex_unlock(&sdata->local->key_mtx);
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}
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void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
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{
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struct ieee80211_key *key, *tmp;
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mutex_lock(&sdata->local->key_mtx);
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ieee80211_debugfs_key_remove_default(sdata);
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ieee80211_debugfs_key_remove_mgmt_default(sdata);
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list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
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__ieee80211_key_free(key);
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mutex_unlock(&sdata->local->key_mtx);
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}
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