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/*
* Copyright 2002-2005, Instant802 Networks, Inc.
* Copyright 2005-2006, Devicescape Software, Inc.
* Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
* Copyright 2007-2008 Johannes Berg <johannes@sipsolutions.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/if_ether.h>
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <net/mac80211.h>
#include <asm/unaligned.h>
#include "ieee80211_i.h"
#include "driver-ops.h"
#include "debugfs_key.h"
#include "aes_ccm.h"
#include "aes_cmac.h"
/**
* DOC: Key handling basics
*
* Key handling in mac80211 is done based on per-interface (sub_if_data)
* keys and per-station keys. Since each station belongs to an interface,
* each station key also belongs to that interface.
*
* Hardware acceleration is done on a best-effort basis for algorithms
* that are implemented in software, for each key the hardware is asked
* to enable that key for offloading but if it cannot do that the key is
* simply kept for software encryption (unless it is for an algorithm
* that isn't implemented in software).
* There is currently no way of knowing whether a key is handled in SW
* or HW except by looking into debugfs.
*
* All key management is internally protected by a mutex. Within all
* other parts of mac80211, key references are, just as STA structure
* references, protected by RCU. Note, however, that some things are
* unprotected, namely the key->sta dereferences within the hardware
* acceleration functions. This means that sta_info_destroy() must
* remove the key which waits for an RCU grace period.
*/
static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
static void assert_key_lock(struct ieee80211_local *local)
{
lockdep_assert_held(&local->key_mtx);
}
static void increment_tailroom_need_count(struct ieee80211_sub_if_data *sdata)
{
/*
* When this count is zero, SKB resizing for allocating tailroom
* for IV or MMIC is skipped. But, this check has created two race
* cases in xmit path while transiting from zero count to one:
*
* 1. SKB resize was skipped because no key was added but just before
* the xmit key is added and SW encryption kicks off.
*
* 2. SKB resize was skipped because all the keys were hw planted but
* just before xmit one of the key is deleted and SW encryption kicks
* off.
*
* In both the above case SW encryption will find not enough space for
* tailroom and exits with WARN_ON. (See WARN_ONs at wpa.c)
*
* Solution has been explained at
* http://mid.gmane.org/1308590980.4322.19.camel@jlt3.sipsolutions.net
*/
if (!sdata->crypto_tx_tailroom_needed_cnt++) {
/*
* Flush all XMIT packets currently using HW encryption or no
* encryption at all if the count transition is from 0 -> 1.
*/
synchronize_net();
}
}
static int ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
{
struct ieee80211_sub_if_data *sdata;
struct sta_info *sta;
int ret;
might_sleep();
if (!key->local->ops->set_key)
goto out_unsupported;
assert_key_lock(key->local);
sta = key->sta;
/*
* If this is a per-STA GTK, check if it
* is supported; if not, return.
*/
if (sta && !(key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE) &&
!(key->local->hw.flags & IEEE80211_HW_SUPPORTS_PER_STA_GTK))
goto out_unsupported;
if (sta && !sta->uploaded)
goto out_unsupported;
sdata = key->sdata;
if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
/*
* The driver doesn't know anything about VLAN interfaces.
* Hence, don't send GTKs for VLAN interfaces to the driver.
*/
if (!(key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE))
goto out_unsupported;
}
ret = drv_set_key(key->local, SET_KEY, sdata,
sta ? &sta->sta : NULL, &key->conf);
if (!ret) {
key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
(key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) ||
(key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)))
sdata->crypto_tx_tailroom_needed_cnt--;
WARN_ON((key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE) &&
(key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV));
return 0;
}
if (ret != -ENOSPC && ret != -EOPNOTSUPP)
wiphy_err(key->local->hw.wiphy,
"failed to set key (%d, %pM) to hardware (%d)\n",
key->conf.keyidx,
sta ? sta->sta.addr : bcast_addr, ret);
out_unsupported:
switch (key->conf.cipher) {
case WLAN_CIPHER_SUITE_WEP40:
case WLAN_CIPHER_SUITE_WEP104:
case WLAN_CIPHER_SUITE_TKIP:
case WLAN_CIPHER_SUITE_CCMP:
case WLAN_CIPHER_SUITE_AES_CMAC:
/* all of these we can do in software */
return 0;
default:
return -EINVAL;
}
}
static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
{
struct ieee80211_sub_if_data *sdata;
struct sta_info *sta;
int ret;
might_sleep();
if (!key || !key->local->ops->set_key)
return;
assert_key_lock(key->local);
if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
return;
sta = key->sta;
sdata = key->sdata;
if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
(key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) ||
(key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)))
increment_tailroom_need_count(sdata);
ret = drv_set_key(key->local, DISABLE_KEY, sdata,
sta ? &sta->sta : NULL, &key->conf);
if (ret)
wiphy_err(key->local->hw.wiphy,
"failed to remove key (%d, %pM) from hardware (%d)\n",
key->conf.keyidx,
sta ? sta->sta.addr : bcast_addr, ret);
key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
}
void ieee80211_key_removed(struct ieee80211_key_conf *key_conf)
{
struct ieee80211_key *key;
key = container_of(key_conf, struct ieee80211_key, conf);
might_sleep();
assert_key_lock(key->local);
key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
/*
* Flush TX path to avoid attempts to use this key
* after this function returns. Until then, drivers
* must be prepared to handle the key.
*/
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(ieee80211_key_removed);
static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
int idx, bool uni, bool multi)
{
struct ieee80211_key *key = NULL;
assert_key_lock(sdata->local);
if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
key = key_mtx_dereference(sdata->local, sdata->keys[idx]);
if (uni)
rcu_assign_pointer(sdata->default_unicast_key, key);
if (multi)
rcu_assign_pointer(sdata->default_multicast_key, key);
ieee80211_debugfs_key_update_default(sdata);
}
void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx,
bool uni, bool multi)
{
mutex_lock(&sdata->local->key_mtx);
__ieee80211_set_default_key(sdata, idx, uni,
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