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 2007-2008  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 key operations are protected internally so you can call them at
  37  * any time.
  38  *
  39  * Within mac80211, key references are, just as STA structure references,
  40  * protected by RCU. Note, however, that some things are unprotected,
  41  * namely the key->sta dereferences within the hardware acceleration
  42  * functions. This means that sta_info_destroy() must flush the key todo
  43  * list.
  44  *
  45  * All the direct key list manipulation functions must not sleep because
  46  * they can operate on STA info structs that are protected by RCU.
  47  */
  48
  49 static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  50 static const u8 zero_addr[ETH_ALEN];
  51
  52 /* key mutex: used to synchronise todo runners */
  53 static DEFINE_MUTEX(key_mutex);
  54 static DEFINE_SPINLOCK(todo_lock);
  55 static LIST_HEAD(todo_list);
  56
  57 static void key_todo(struct work_struct *work)
  58 {
  59         ieee80211_key_todo();
  60 }
  61
  62 static DECLARE_WORK(todo_work, key_todo);
  63
  64 /**
  65  * add_todo - add todo item for a key
  66  *
  67  * @key: key to add to do item for
  68  * @flag: todo flag(s)
  69  */
  70 static void add_todo(struct ieee80211_key *key, u32 flag)
  71 {
  72         if (!key)
  73                 return;
  74
  75         spin_lock(&todo_lock);
  76         key->flags |= flag;
  77         /* only add if not already added */
  78         if (list_empty(&key->todo))
  79                 list_add(&key->todo, &todo_list);
  80         schedule_work(&todo_work);
  81         spin_unlock(&todo_lock);
  82 }
  83
  84 /**
  85  * ieee80211_key_lock - lock the mac80211 key operation lock
  86  *
  87  * This locks the (global) mac80211 key operation lock, all
  88  * key operations must be done under this lock.
  89  */
  90 static void ieee80211_key_lock(void)
  91 {
  92         mutex_lock(&key_mutex);
  93 }
  94
  95 /**
  96  * ieee80211_key_unlock - unlock the mac80211 key operation lock
  97  */
  98 static void ieee80211_key_unlock(void)
  99 {
 100         mutex_unlock(&key_mutex);
 101 }
 102
 103 static void assert_key_lock(void)
 104 {
 105         WARN_ON(!mutex_is_locked(&key_mutex));
 106 }
 107
 108 static const u8 *get_mac_for_key(struct ieee80211_key *key)
 109 {
 110         const u8 *addr = bcast_addr;
 111
 112         /*
 113          * If we're an AP we won't ever receive frames with a non-WEP
 114          * group key so we tell the driver that by using the zero MAC
 115          * address to indicate a transmit-only key.
 116          */
 117         if (key->conf.alg != ALG_WEP &&
 118             (key->sdata->vif.type == IEEE80211_IF_TYPE_AP ||
 119              key->sdata->vif.type == IEEE80211_IF_TYPE_VLAN))
 120                 addr = zero_addr;
 121
 122         if (key->sta)
 123                 addr = key->sta->addr;
 124
 125         return addr;
 126 }
 127
 128 static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
 129 {
 130         const u8 *addr;
 131         int ret;
 132         DECLARE_MAC_BUF(mac);
 133
 134         assert_key_lock();
 135         might_sleep();
 136
 137         if (!key->local->ops->set_key)
 138                 return;
 139
 140         addr = get_mac_for_key(key);
 141
 142         ret = key->local->ops->set_key(local_to_hw(key->local), SET_KEY,
 143                                        key->sdata->dev->dev_addr, addr,
 144                                        &key->conf);
 145
 146         if (!ret) {
 147                 spin_lock(&todo_lock);
 148                 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
 149                 spin_unlock(&todo_lock);
 150         }
 151
 152         if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
 153                 printk(KERN_ERR "mac80211-%s: failed to set key "
 154                        "(%d, %s) to hardware (%d)\n",
 155                        wiphy_name(key->local->hw.wiphy),
 156                        key->conf.keyidx, print_mac(mac, addr), ret);
 157 }
 158
 159 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
 160 {
 161         const u8 *addr;
 162         int ret;
 163         DECLARE_MAC_BUF(mac);
 164
 165         assert_key_lock();
 166         might_sleep();
 167
 168         if (!key || !key->local->ops->set_key)
 169                 return;
 170
 171         spin_lock(&todo_lock);
 172         if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
 173                 spin_unlock(&todo_lock);
 174                 return;
 175         }
 176         spin_unlock(&todo_lock);
 177
 178         addr = get_mac_for_key(key);
 179
 180         ret = key->local->ops->set_key(local_to_hw(key->local), DISABLE_KEY,
 181                                        key->sdata->dev->dev_addr, addr,
 182                                        &key->conf);
 183
 184         if (ret)
 185                 printk(KERN_ERR "mac80211-%s: failed to remove key "
 186                        "(%d, %s) from hardware (%d)\n",
 187                        wiphy_name(key->local->hw.wiphy),
 188                        key->conf.keyidx, print_mac(mac, addr), ret);
 189
 190         spin_lock(&todo_lock);
 191         key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
 192         spin_unlock(&todo_lock);
 193 }
 194
 195 static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
 196                                         int idx)
 197 {
 198         struct ieee80211_key *key = NULL;
 199
 200         if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
 201                 key = sdata->keys[idx];
 202
 203         rcu_assign_pointer(sdata->default_key, key);
 204
 205         if (key)
 206                 add_todo(key, KEY_FLAG_TODO_DEFKEY);
 207 }
 208
 209 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
 210 {
 211         unsigned long flags;
 212
 213         spin_lock_irqsave(&sdata->local->sta_lock, flags);
 214         __ieee80211_set_default_key(sdata, idx);
 215         spin_unlock_irqrestore(&sdata->local->sta_lock, flags);
 216 }
 217
 218
 219 static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
 220                                     struct sta_info *sta,
 221                                     struct ieee80211_key *old,
 222                                     struct ieee80211_key *new)
 223 {
 224         int idx, defkey;
 225
 226         if (new)
 227                 list_add(&new->list, &sdata->key_list);
 228
 229         if (sta) {
 230                 rcu_assign_pointer(sta->key, new);
 231         } else {
 232                 WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);
 233
 234                 if (old)
 235                         idx = old->conf.keyidx;
 236                 else
 237                         idx = new->conf.keyidx;
 238
 239                 defkey = old && sdata->default_key == old;
 240
 241                 if (defkey && !new)
 242                         __ieee80211_set_default_key(sdata, -1);
 243
 244                 rcu_assign_pointer(sdata->keys[idx], new);
 245                 if (defkey && new)
 246                         __ieee80211_set_default_key(sdata, new->conf.keyidx);
 247         }
 248
 249         if (old) {
 250                 /*
 251                  * We'll use an empty list to indicate that the key
 252                  * has already been removed.
 253                  */
 254                 list_del_init(&old->list);
 255         }
 256 }
 257
 258 struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
 259                                           int idx,
 260                                           size_t key_len,
 261                                           const u8 *key_data)
 262 {
 263         struct ieee80211_key *key;
 264
 265         BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS);
 266
 267         key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
 268         if (!key)
 269                 return NULL;
 270
 271         /*
 272          * Default to software encryption; we'll later upload the
 273          * key to the hardware if possible.
 274          */
 275         key->conf.flags = 0;
 276         key->flags = 0;
 277
 278         key->conf.alg = alg;
 279         key->conf.keyidx = idx;
 280         key->conf.keylen = key_len;
 281         memcpy(key->conf.key, key_data, key_len);
 282         INIT_LIST_HEAD(&key->list);
 283         INIT_LIST_HEAD(&key->todo);
 284
 285         if (alg == ALG_CCMP) {
 286                 /*
 287                  * Initialize AES key state here as an optimization so that
 288                  * it does not need to be initialized for every packet.
 289                  */
 290                 key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
 291                 if (!key->u.ccmp.tfm) {
 292                         kfree(key);
 293                         return NULL;
 294                 }
 295         }
 296
 297         return key;
 298 }
 299
 300 void ieee80211_key_link(struct ieee80211_key *key,
 301                         struct ieee80211_sub_if_data *sdata,
 302                         struct sta_info *sta)
 303 {
 304         struct ieee80211_key *old_key;
 305         unsigned long flags;
 306         int idx;
 307
 308         BUG_ON(!sdata);
 309         BUG_ON(!key);
 310
 311         idx = key->conf.keyidx;
 312         key->local = sdata->local;
 313         key->sdata = sdata;
 314         key->sta = sta;
 315
 316         if (sta) {
 317                 /*
 318                  * some hardware cannot handle TKIP with QoS, so
 319                  * we indicate whether QoS could be in use.
 320                  */
 321                 if (sta->flags & WLAN_STA_WME)
 322                         key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
 323         } else {
 324                 if (sdata->vif.type == IEEE80211_IF_TYPE_STA) {
 325                         struct sta_info *ap;
 326
 327                         /*
 328                          * We're getting a sta pointer in,
 329                          * so must be under RCU read lock.
 330                          */
 331
 332                         /* same here, the AP could be using QoS */
 333                         ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
 334                         if (ap) {
 335                                 if (ap->flags & WLAN_STA_WME)
 336                                         key->conf.flags |=
 337                                                 IEEE80211_KEY_FLAG_WMM_STA;
 338                         }
 339                 }
 340         }
 341
 342         spin_lock_irqsave(&sdata->local->sta_lock, flags);
 343
 344         if (sta)
 345                 old_key = sta->key;
 346         else
 347                 old_key = sdata->keys[idx];
 348
 349         __ieee80211_key_replace(sdata, sta, old_key, key);
 350
 351         spin_unlock_irqrestore(&sdata->local->sta_lock, flags);
 352
 353         /* free old key later */
 354         add_todo(old_key, KEY_FLAG_TODO_DELETE);
 355
 356         add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
 357         if (netif_running(sdata->dev))
 358                 add_todo(key, KEY_FLAG_TODO_HWACCEL);
 359 }
 360
 361 void ieee80211_key_free(struct ieee80211_key *key)
 362 {
 363         unsigned long flags;
 364
 365         if (!key)
 366                 return;
 367
 368         /*
 369          * Replace key with nothingness if it was ever used.
 370          */
 371         if (key->sdata) {
 372                 spin_lock_irqsave(&key->sdata->local->sta_lock, flags);
 373                 __ieee80211_key_replace(key->sdata, key->sta,
 374                                         key, NULL);
 375                 spin_unlock_irqrestore(&key->sdata->local->sta_lock, flags);
 376         }
 377
 378         add_todo(key, KEY_FLAG_TODO_DELETE);
 379 }
 380
 381 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
 382 {
 383         struct ieee80211_key *key;
 384
 385         might_sleep();
 386
 387         if (WARN_ON(!netif_running(sdata->dev)))
 388                 return;
 389
 390         ieee80211_key_lock();
 391
 392         list_for_each_entry(key, &sdata->key_list, list)
 393                 ieee80211_key_enable_hw_accel(key);
 394
 395         ieee80211_key_unlock();
 396 }
 397
 398 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
 399 {
 400         struct ieee80211_key *key;
 401
 402         might_sleep();
 403
 404         ieee80211_key_lock();
 405
 406         list_for_each_entry(key, &sdata->key_list, list)
 407                 ieee80211_key_disable_hw_accel(key);
 408
 409         ieee80211_key_unlock();
 410 }
 411
 412 static void __ieee80211_key_free(struct ieee80211_key *key)
 413 {
 414         if (!key)
 415                 return;
 416
 417         ieee80211_key_disable_hw_accel(key);
 418
 419         if (key->conf.alg == ALG_CCMP)
 420                 ieee80211_aes_key_free(key->u.ccmp.tfm);
 421         ieee80211_debugfs_key_remove(key);
 422
 423         kfree(key);
 424 }
 425
 426 static void __ieee80211_key_todo(void)
 427 {
 428         struct ieee80211_key *key;
 429         bool work_done;
 430         u32 todoflags;
 431
 432         /*
 433          * NB: sta_info_destroy relies on this!
 434          */
 435         synchronize_rcu();
 436
 437         spin_lock(&todo_lock);
 438         while (!list_empty(&todo_list)) {
 439                 key = list_first_entry(&todo_list, struct ieee80211_key, todo);
 440                 list_del_init(&key->todo);
 441                 todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
 442                                           KEY_FLAG_TODO_DEFKEY |
 443                                           KEY_FLAG_TODO_HWACCEL |
 444                                           KEY_FLAG_TODO_DELETE);
 445                 key->flags &= ~todoflags;
 446                 spin_unlock(&todo_lock);
 447
 448                 work_done = false;
 449
 450                 if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
 451                         ieee80211_debugfs_key_add(key);
 452                         work_done = true;
 453                 }
 454                 if (todoflags & KEY_FLAG_TODO_DEFKEY) {
 455                         ieee80211_debugfs_key_remove_default(key->sdata);
 456                         ieee80211_debugfs_key_add_default(key->sdata);
 457                         work_done = true;
 458                 }
 459                 if (todoflags & KEY_FLAG_TODO_HWACCEL) {
 460                         ieee80211_key_enable_hw_accel(key);
 461                         work_done = true;
 462                 }
 463                 if (todoflags & KEY_FLAG_TODO_DELETE) {
 464                         __ieee80211_key_free(key);
 465                         work_done = true;
 466                 }
 467
 468                 WARN_ON(!work_done);
 469
 470                 spin_lock(&todo_lock);
 471         }
 472         spin_unlock(&todo_lock);
 473 }
 474
 475 void ieee80211_key_todo(void)
 476 {
 477         ieee80211_key_lock();
 478         __ieee80211_key_todo();
 479         ieee80211_key_unlock();
 480 }
 481
 482 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 483 {
 484         struct ieee80211_key *key, *tmp;
 485         LIST_HEAD(tmp_list);
 486
 487         ieee80211_key_lock();
 488
 489         ieee80211_debugfs_key_remove_default(sdata);
 490
 491         list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
 492                 ieee80211_key_free(key);
 493
 494         __ieee80211_key_todo();
 495
 496         ieee80211_key_unlock();
 497 }