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 <linux/rtnetlink.h>
  17 #include <net/mac80211.h>
  18 #include "ieee80211_i.h"
  19 #include "debugfs_key.h"
  20 #include "aes_ccm.h"
  21
  22
  23 /**
  24  * DOC: Key handling basics
  25  *
  26  * Key handling in mac80211 is done based on per-interface (sub_if_data)
  27  * keys and per-station keys. Since each station belongs to an interface,
  28  * each station key also belongs to that interface.
  29  *
  30  * Hardware acceleration is done on a best-effort basis, for each key
  31  * that is eligible the hardware is asked to enable that key but if
  32  * it cannot do that they key is simply kept for software encryption.
  33  * There is currently no way of knowing this except by looking into
  34  * debugfs.
  35  *
  36  * All operations here are called under RTNL so no extra locking is
  37  * required.
  38  *
  39  * NOTE: This code requires that sta info *destruction* is done under
  40  *       RTNL, otherwise it can try to access already freed STA structs
  41  *       when a STA key is being freed.
  42  */
  43
  44 static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  45 static const u8 zero_addr[ETH_ALEN];
  46
  47 static const u8 *get_mac_for_key(struct ieee80211_key *key)
  48 {
  49         const u8 *addr = bcast_addr;
  50
  51         /*
  52          * If we're an AP we won't ever receive frames with a non-WEP
  53          * group key so we tell the driver that by using the zero MAC
  54          * address to indicate a transmit-only key.
  55          */
  56         if (key->conf.alg != ALG_WEP &&
  57             (key->sdata->vif.type == IEEE80211_IF_TYPE_AP ||
  58              key->sdata->vif.type == IEEE80211_IF_TYPE_VLAN))
  59                 addr = zero_addr;
  60
  61         if (key->sta)
  62                 addr = key->sta->addr;
  63
  64         return addr;
  65 }
  66
  67 static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
  68 {
  69         const u8 *addr;
  70         int ret;
  71         DECLARE_MAC_BUF(mac);
  72
  73         if (!key->local->ops->set_key)
  74                 return;
  75
  76         /*
  77          * This makes sure that all pending flushes have
  78          * actually completed prior to uploading new key
  79          * material to the hardware. That is necessary to
  80          * avoid races between flushing STAs and adding
  81          * new keys for them.
  82          */
  83         __ieee80211_run_pending_flush(key->local);
  84
  85         addr = get_mac_for_key(key);
  86
  87         ret = key->local->ops->set_key(local_to_hw(key->local), SET_KEY,
  88                                        key->sdata->dev->dev_addr, addr,
  89                                        &key->conf);
  90
  91         if (!ret)
  92                 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
  93
  94         if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
  95                 printk(KERN_ERR "mac80211-%s: failed to set key "
  96                        "(%d, %s) to hardware (%d)\n",
  97                        wiphy_name(key->local->hw.wiphy),
  98                        key->conf.keyidx, print_mac(mac, addr), ret);
  99 }
 100
 101 static void ieee80211_key_mark_hw_accel_off(struct ieee80211_key *key)
 102 {
 103         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 104                 key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
 105                 key->flags |= KEY_FLAG_REMOVE_FROM_HARDWARE;
 106         }
 107 }
 108
 109 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
 110 {
 111         const u8 *addr;
 112         int ret;
 113         DECLARE_MAC_BUF(mac);
 114
 115         if (!key || !key->local->ops->set_key)
 116                 return;
 117
 118         if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
 119             !(key->flags & KEY_FLAG_REMOVE_FROM_HARDWARE))
 120                 return;
 121
 122         addr = get_mac_for_key(key);
 123
 124         ret = key->local->ops->set_key(local_to_hw(key->local), DISABLE_KEY,
 125                                        key->sdata->dev->dev_addr, addr,
 126                                        &key->conf);
 127
 128         if (ret)
 129                 printk(KERN_ERR "mac80211-%s: failed to remove key "
 130                        "(%d, %s) from hardware (%d)\n",
 131                        wiphy_name(key->local->hw.wiphy),
 132                        key->conf.keyidx, print_mac(mac, addr), ret);
 133
 134         key->flags &= ~(KEY_FLAG_UPLOADED_TO_HARDWARE |
 135                         KEY_FLAG_REMOVE_FROM_HARDWARE);
 136 }
 137
 138 struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
 139                                           int idx,
 140                                           size_t key_len,
 141                                           const u8 *key_data)
 142 {
 143         struct ieee80211_key *key;
 144
 145         BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS);
 146
 147         key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
 148         if (!key)
 149                 return NULL;
 150
 151         /*
 152          * Default to software encryption; we'll later upload the
 153          * key to the hardware if possible.
 154          */
 155         key->conf.flags = 0;
 156         key->flags = 0;
 157
 158         key->conf.alg = alg;
 159         key->conf.keyidx = idx;
 160         key->conf.keylen = key_len;
 161         memcpy(key->conf.key, key_data, key_len);
 162         INIT_LIST_HEAD(&key->list);
 163
 164         if (alg == ALG_CCMP) {
 165                 /*
 166                  * Initialize AES key state here as an optimization so that
 167                  * it does not need to be initialized for every packet.
 168                  */
 169                 key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
 170                 if (!key->u.ccmp.tfm) {
 171                         ieee80211_key_free(key);
 172                         return NULL;
 173                 }
 174         }
 175
 176         return key;
 177 }
 178
 179 static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
 180                                     struct sta_info *sta,
 181                                     struct ieee80211_key *key,
 182                                     struct ieee80211_key *new)
 183 {
 184         int idx, defkey;
 185
 186         if (new)
 187                 list_add(&new->list, &sdata->key_list);
 188
 189         if (sta) {
 190                 rcu_assign_pointer(sta->key, new);
 191         } else {
 192                 WARN_ON(new && key && new->conf.keyidx != key->conf.keyidx);
 193
 194                 if (key)
 195                         idx = key->conf.keyidx;
 196                 else
 197                         idx = new->conf.keyidx;
 198
 199                 defkey = key && sdata->default_key == key;
 200
 201                 if (defkey && !new)
 202                         ieee80211_set_default_key(sdata, -1);
 203
 204                 rcu_assign_pointer(sdata->keys[idx], new);
 205                 if (defkey && new)
 206                         ieee80211_set_default_key(sdata, new->conf.keyidx);
 207         }
 208
 209         if (key) {
 210                 ieee80211_key_mark_hw_accel_off(key);
 211                 /*
 212                  * We'll use an empty list to indicate that the key
 213                  * has already been removed.
 214                  */
 215                 list_del_init(&key->list);
 216         }
 217 }
 218
 219 void ieee80211_key_link(struct ieee80211_key *key,
 220                         struct ieee80211_sub_if_data *sdata,
 221                         struct sta_info *sta)
 222 {
 223         struct ieee80211_key *old_key;
 224         int idx;
 225
 226         ASSERT_RTNL();
 227         might_sleep();
 228
 229         BUG_ON(!sdata);
 230         BUG_ON(!key);
 231
 232         idx = key->conf.keyidx;
 233         key->local = sdata->local;
 234         key->sdata = sdata;
 235         key->sta = sta;
 236
 237         ieee80211_debugfs_key_add(key->local, key);
 238
 239         if (sta) {
 240                 ieee80211_debugfs_key_sta_link(key, sta);
 241
 242                 /*
 243                  * some hardware cannot handle TKIP with QoS, so
 244                  * we indicate whether QoS could be in use.
 245                  */
 246                 if (sta->flags & WLAN_STA_WME)
 247                         key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
 248         } else {
 249                 if (sdata->vif.type == IEEE80211_IF_TYPE_STA) {
 250                         struct sta_info *ap;
 251
 252                         rcu_read_lock();
 253
 254                         /* same here, the AP could be using QoS */
 255                         ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
 256                         if (ap) {
 257                                 if (ap->flags & WLAN_STA_WME)
 258                                         key->conf.flags |=
 259                                                 IEEE80211_KEY_FLAG_WMM_STA;
 260                         }
 261
 262                         rcu_read_unlock();
 263                 }
 264         }
 265
 266         if (sta)
 267                 old_key = sta->key;
 268         else
 269                 old_key = sdata->keys[idx];
 270
 271         __ieee80211_key_replace(sdata, sta, old_key, key);
 272
 273         if (old_key) {
 274                 synchronize_rcu();
 275                 ieee80211_key_free(old_key);
 276         }
 277
 278         if (netif_running(sdata->dev))
 279                 ieee80211_key_enable_hw_accel(key);
 280 }
 281
 282 void ieee80211_key_free(struct ieee80211_key *key)
 283 {
 284         ASSERT_RTNL();
 285         might_sleep();
 286
 287         if (!key)
 288                 return;
 289
 290         if (key->sdata) {
 291                 /*
 292                  * Replace key with nothingness.
 293                  *
 294                  * Because other code may have key reference (RCU protected)
 295                  * right now, we then wait for a grace period before freeing
 296                  * it.
 297                  * An empty list indicates it was never added to the key list
 298                  * or has been removed already. It may, however, still be in
 299                  * hardware for acceleration.
 300                  */
 301                 if (!list_empty(&key->list))
 302                         __ieee80211_key_replace(key->sdata, key->sta,
 303                                                 key, NULL);
 304
 305                 /*
 306                  * Do NOT remove this without looking at sta_info_destroy()
 307                  */
 308                 synchronize_rcu();
 309
 310                 /*
 311                  * Remove from hwaccel if appropriate, this will
 312                  * only happen when the key is actually unlinked,
 313                  * it will already be done when the key was replaced.
 314                  */
 315                 ieee80211_key_disable_hw_accel(key);
 316         }
 317
 318         if (key->conf.alg == ALG_CCMP)
 319                 ieee80211_aes_key_free(key->u.ccmp.tfm);
 320         ieee80211_debugfs_key_remove(key);
 321
 322         kfree(key);
 323 }
 324
 325 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
 326 {
 327         struct ieee80211_key *key = NULL;
 328
 329         if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
 330                 key = sdata->keys[idx];
 331
 332         if (sdata->default_key != key) {
 333                 ieee80211_debugfs_key_remove_default(sdata);
 334
 335                 rcu_assign_pointer(sdata->default_key, key);
 336
 337                 if (sdata->default_key)
 338                         ieee80211_debugfs_key_add_default(sdata);
 339         }
 340 }
 341
 342 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 343 {
 344         struct ieee80211_key *key, *tmp;
 345         LIST_HEAD(tmp_list);
 346
 347         ASSERT_RTNL();
 348         might_sleep();
 349
 350         list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
 351                 ieee80211_key_free(key);
 352 }
 353
 354 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
 355 {
 356         struct ieee80211_key *key;
 357
 358         ASSERT_RTNL();
 359         might_sleep();
 360
 361         if (WARN_ON(!netif_running(sdata->dev)))
 362                 return;
 363
 364         list_for_each_entry(key, &sdata->key_list, list)
 365                 ieee80211_key_enable_hw_accel(key);
 366 }
 367
 368 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
 369 {
 370         struct ieee80211_key *key;
 371
 372         ASSERT_RTNL();
 373         might_sleep();
 374
 375         list_for_each_entry(key, &sdata->key_list, list)
 376                 ieee80211_key_disable_hw_accel(key);
 377 }