net/mac80211/key.c

   1 /*
   2  * Copyright 2002-2005, Instant802 Networks, Inc.
   3  * Copyright 2005-2006, Devicescape Software, Inc.
   4  * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
   5  * Copyright 2007       Johannes Berg <johannes@sipsolutions.net>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/if_ether.h>
  13 #include <linux/etherdevice.h>
  14 #include <linux/list.h>
  15 #include <linux/rcupdate.h>
  16 #include <net/mac80211.h>
  17 #include "ieee80211_i.h"
  18 #include "debugfs_key.h"
  19 #include "aes_ccm.h"
  20
  21
  22 /*
  23  * Key handling basics
  24  *
  25  * Key handling in mac80211 is done based on per-interface (sub_if_data)
  26  * keys and per-station keys. Since each station belongs to an interface,
  27  * each station key also belongs to that interface.
  28  *
  29  * Hardware acceleration is done on a best-effort basis, for each key
  30  * that is eligible the hardware is asked to enable that key but if
  31  * it cannot do that they key is simply kept for software encryption.
  32  * There is currently no way of knowing this except by looking into
  33  * debugfs.
  34  *
  35  * All operations here are called under RTNL so no extra locking is
  36  * required.
  37  */
  38
  39 static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  40 static const u8 zero_addr[ETH_ALEN];
  41
  42 static const u8 *get_mac_for_key(struct ieee80211_key *key)
  43 {
  44         const u8 *addr = bcast_addr;
  45
  46         /*
  47          * If we're an AP we won't ever receive frames with a non-WEP
  48          * group key so we tell the driver that by using the zero MAC
  49          * address to indicate a transmit-only key.
  50          */
  51         if (key->conf.alg != ALG_WEP &&
  52             (key->sdata->type == IEEE80211_IF_TYPE_AP ||
  53              key->sdata->type == IEEE80211_IF_TYPE_VLAN))
  54                 addr = zero_addr;
  55
  56         if (key->sta)
  57                 addr = key->sta->addr;
  58
  59         return addr;
  60 }
  61
  62 static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
  63 {
  64         const u8 *addr;
  65         int ret;
  66         DECLARE_MAC_BUF(mac);
  67
  68         if (!key->local->ops->set_key)
  69                 return;
  70
  71         addr = get_mac_for_key(key);
  72
  73         ret = key->local->ops->set_key(local_to_hw(key->local), SET_KEY,
  74                                        key->sdata->dev->dev_addr, addr,
  75                                        &key->conf);
  76
  77         if (!ret)
  78                 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
  79
  80         if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
  81                 printk(KERN_ERR "mac80211-%s: failed to set key "
  82                        "(%d, %s) to hardware (%d)\n",
  83                        wiphy_name(key->local->hw.wiphy),
  84                        key->conf.keyidx, print_mac(mac, addr), ret);
  85 }
  86
  87 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
  88 {
  89         const u8 *addr;
  90         int ret;
  91         DECLARE_MAC_BUF(mac);
  92
  93         if (!key->local->ops->set_key)
  94                 return;
  95
  96         if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
  97                 return;
  98
  99         addr = get_mac_for_key(key);
 100
 101         ret = key->local->ops->set_key(local_to_hw(key->local), DISABLE_KEY,
 102                                        key->sdata->dev->dev_addr, addr,
 103                                        &key->conf);
 104
 105         if (ret)
 106                 printk(KERN_ERR "mac80211-%s: failed to remove key "
 107                        "(%d, %s) from hardware (%d)\n",
 108                        wiphy_name(key->local->hw.wiphy),
 109                        key->conf.keyidx, print_mac(mac, addr), ret);
 110
 111         key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
 112 }
 113
 114 struct ieee80211_key *ieee80211_key_alloc(struct ieee80211_sub_if_data *sdata,
 115                                           struct sta_info *sta,
 116                                           enum ieee80211_key_alg alg,
 117                                           int idx,
 118                                           size_t key_len,
 119                                           const u8 *key_data)
 120 {
 121         struct ieee80211_key *key;
 122
 123         BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS);
 124
 125         key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
 126         if (!key)
 127                 return NULL;
 128
 129         /*
 130          * Default to software encryption; we'll later upload the
 131          * key to the hardware if possible.
 132          */
 133         key->conf.flags = 0;
 134         key->flags = 0;
 135
 136         key->conf.alg = alg;
 137         key->conf.keyidx = idx;
 138         key->conf.keylen = key_len;
 139         memcpy(key->conf.key, key_data, key_len);
 140
 141         key->local = sdata->local;
 142         key->sdata = sdata;
 143         key->sta = sta;
 144
 145         if (alg == ALG_CCMP) {
 146                 /*
 147                  * Initialize AES key state here as an optimization so that
 148                  * it does not need to be initialized for every packet.
 149                  */
 150                 key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
 151                 if (!key->u.ccmp.tfm) {
 152                         ieee80211_key_free(key);
 153                         return NULL;
 154                 }
 155         }
 156
 157         ieee80211_debugfs_key_add(key->local, key);
 158
 159         /* remove key first */
 160         if (sta)
 161                 ieee80211_key_free(sta->key);
 162         else
 163                 ieee80211_key_free(sdata->keys[idx]);
 164
 165         if (sta) {
 166                 ieee80211_debugfs_key_sta_link(key, sta);
 167
 168                 /*
 169                  * some hardware cannot handle TKIP with QoS, so
 170                  * we indicate whether QoS could be in use.
 171                  */
 172                 if (sta->flags & WLAN_STA_WME)
 173                         key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
 174         } else {
 175                 if (sdata->type == IEEE80211_IF_TYPE_STA) {
 176                         struct sta_info *ap;
 177
 178                         /* same here, the AP could be using QoS */
 179                         ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
 180                         if (ap) {
 181                                 if (ap->flags & WLAN_STA_WME)
 182                                         key->conf.flags |=
 183                                                 IEEE80211_KEY_FLAG_WMM_STA;
 184                                 sta_info_put(ap);
 185                         }
 186                 }
 187         }
 188
 189         /* enable hwaccel if appropriate */
 190         if (netif_running(key->sdata->dev))
 191                 ieee80211_key_enable_hw_accel(key);
 192
 193         if (sta)
 194                 rcu_assign_pointer(sta->key, key);
 195         else
 196                 rcu_assign_pointer(sdata->keys[idx], key);
 197
 198         list_add(&key->list, &sdata->key_list);
 199
 200         return key;
 201 }
 202
 203 void ieee80211_key_free(struct ieee80211_key *key)
 204 {
 205         if (!key)
 206                 return;
 207
 208         if (key->sta) {
 209                 rcu_assign_pointer(key->sta->key, NULL);
 210         } else {
 211                 if (key->sdata->default_key == key)
 212                         ieee80211_set_default_key(key->sdata, -1);
 213                 if (key->conf.keyidx >= 0 &&
 214                     key->conf.keyidx < NUM_DEFAULT_KEYS)
 215                         rcu_assign_pointer(key->sdata->keys[key->conf.keyidx],
 216                                            NULL);
 217                 else
 218                         WARN_ON(1);
 219         }
 220
 221         /* wait for all key users to complete */
 222         synchronize_rcu();
 223
 224         /* remove from hwaccel if appropriate */
 225         ieee80211_key_disable_hw_accel(key);
 226
 227         if (key->conf.alg == ALG_CCMP)
 228                 ieee80211_aes_key_free(key->u.ccmp.tfm);
 229         ieee80211_debugfs_key_remove(key);
 230
 231         list_del(&key->list);
 232
 233         kfree(key);
 234 }
 235
 236 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
 237 {
 238         struct ieee80211_key *key = NULL;
 239
 240         if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
 241                 key = sdata->keys[idx];
 242
 243         if (sdata->default_key != key) {
 244                 ieee80211_debugfs_key_remove_default(sdata);
 245
 246                 rcu_assign_pointer(sdata->default_key, key);
 247
 248                 if (sdata->default_key)
 249                         ieee80211_debugfs_key_add_default(sdata);
 250         }
 251 }
 252
 253 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 254 {
 255         struct ieee80211_key *key, *tmp;
 256
 257         list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
 258                 ieee80211_key_free(key);
 259 }
 260
 261 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
 262 {
 263         struct ieee80211_key *key;
 264
 265         WARN_ON(!netif_running(sdata->dev));
 266         if (!netif_running(sdata->dev))
 267                 return;
 268
 269         list_for_each_entry(key, &sdata->key_list, list)
 270                 ieee80211_key_enable_hw_accel(key);
 271 }
 272
 273 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
 274 {
 275         struct ieee80211_key *key;
 276
 277         list_for_each_entry(key, &sdata->key_list, list)
 278                 ieee80211_key_disable_hw_accel(key);
 279 }