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 #include "aes_cmac.h"
  22
  23
  24 /**
  25  * DOC: Key handling basics
  26  *
  27  * Key handling in mac80211 is done based on per-interface (sub_if_data)
  28  * keys and per-station keys. Since each station belongs to an interface,
  29  * each station key also belongs to that interface.
  30  *
  31  * Hardware acceleration is done on a best-effort basis, for each key
  32  * that is eligible the hardware is asked to enable that key but if
  33  * it cannot do that they key is simply kept for software encryption.
  34  * There is currently no way of knowing this except by looking into
  35  * debugfs.
  36  *
  37  * All key operations are protected internally so you can call them at
  38  * any time.
  39  *
  40  * Within mac80211, key references are, just as STA structure references,
  41  * protected by RCU. Note, however, that some things are unprotected,
  42  * namely the key->sta dereferences within the hardware acceleration
  43  * functions. This means that sta_info_destroy() must flush the key todo
  44  * list.
  45  *
  46  * All the direct key list manipulation functions must not sleep because
  47  * they can operate on STA info structs that are protected by RCU.
  48  */
  49
  50 static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  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         /*
  78          * Remove again if already on the list so that we move it to the end.
  79          */
  80         if (!list_empty(&key->todo))
  81                 list_del(&key->todo);
  82         list_add_tail(&key->todo, &todo_list);
  83         schedule_work(&todo_work);
  84         spin_unlock(&todo_lock);
  85 }
  86
  87 /**
  88  * ieee80211_key_lock - lock the mac80211 key operation lock
  89  *
  90  * This locks the (global) mac80211 key operation lock, all
  91  * key operations must be done under this lock.
  92  */
  93 static void ieee80211_key_lock(void)
  94 {
  95         mutex_lock(&key_mutex);
  96 }
  97
  98 /**
  99  * ieee80211_key_unlock - unlock the mac80211 key operation lock
 100  */
 101 static void ieee80211_key_unlock(void)
 102 {
 103         mutex_unlock(&key_mutex);
 104 }
 105
 106 static void assert_key_lock(void)
 107 {
 108         WARN_ON(!mutex_is_locked(&key_mutex));
 109 }
 110
 111 static struct ieee80211_sta *get_sta_for_key(struct ieee80211_key *key)
 112 {
 113         if (key->sta)
 114                 return &key->sta->sta;
 115
 116         return NULL;
 117 }
 118
 119 static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
 120 {
 121         struct ieee80211_sub_if_data *sdata;
 122         struct ieee80211_sta *sta;
 123         int ret;
 124
 125         assert_key_lock();
 126         might_sleep();
 127
 128         if (!key->local->ops->set_key)
 129                 return;
 130
 131         sta = get_sta_for_key(key);
 132
 133         sdata = key->sdata;
 134         if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 135                 sdata = container_of(sdata->bss,
 136                                      struct ieee80211_sub_if_data,
 137                                      u.ap);
 138
 139         ret = key->local->ops->set_key(local_to_hw(key->local), SET_KEY,
 140                                        &sdata->vif, sta, &key->conf);
 141
 142         if (!ret) {
 143                 spin_lock(&todo_lock);
 144                 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
 145                 spin_unlock(&todo_lock);
 146         }
 147
 148         if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
 149                 printk(KERN_ERR "mac80211-%s: failed to set key "
 150                        "(%d, %pM) to hardware (%d)\n",
 151                        wiphy_name(key->local->hw.wiphy),
 152                        key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
 153 }
 154
 155 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
 156 {
 157         struct ieee80211_sub_if_data *sdata;
 158         struct ieee80211_sta *sta;
 159         int ret;
 160
 161         assert_key_lock();
 162         might_sleep();
 163
 164         if (!key || !key->local->ops->set_key)
 165                 return;
 166
 167         spin_lock(&todo_lock);
 168         if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
 169                 spin_unlock(&todo_lock);
 170                 return;
 171         }
 172         spin_unlock(&todo_lock);
 173
 174         sta = get_sta_for_key(key);
 175         sdata = key->sdata;
 176
 177         if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 178                 sdata = container_of(sdata->bss,
 179                                      struct ieee80211_sub_if_data,
 180                                      u.ap);
 181
 182         ret = key->local->ops->set_key(local_to_hw(key->local), DISABLE_KEY,
 183                                        &sdata->vif, sta, &key->conf);
 184
 185         if (ret)
 186                 printk(KERN_ERR "mac80211-%s: failed to remove key "
 187                        "(%d, %pM) from hardware (%d)\n",
 188                        wiphy_name(key->local->hw.wiphy),
 189                        key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
 190
 191         spin_lock(&todo_lock);
 192         key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
 193         spin_unlock(&todo_lock);
 194 }
 195
 196 static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
 197                                         int idx)
 198 {
 199         struct ieee80211_key *key = NULL;
 200
 201         if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
 202                 key = sdata->keys[idx];
 203
 204         rcu_assign_pointer(sdata->default_key, key);
 205
 206         if (key)
 207                 add_todo(key, KEY_FLAG_TODO_DEFKEY);
 208 }
 209
 210 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
 211 {
 212         unsigned long flags;
 213
 214         spin_lock_irqsave(&sdata->local->key_lock, flags);
 215         __ieee80211_set_default_key(sdata, idx);
 216         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 217 }
 218
 219 static void
 220 __ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata, int idx)
 221 {
 222         struct ieee80211_key *key = NULL;
 223
 224         if (idx >= NUM_DEFAULT_KEYS &&
 225             idx < NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
 226                 key = sdata->keys[idx];
 227
 228         rcu_assign_pointer(sdata->default_mgmt_key, key);
 229
 230         if (key)
 231                 add_todo(key, KEY_FLAG_TODO_DEFMGMTKEY);
 232 }
 233
 234 void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
 235                                     int idx)
 236 {
 237         unsigned long flags;
 238
 239         spin_lock_irqsave(&sdata->local->key_lock, flags);
 240         __ieee80211_set_default_mgmt_key(sdata, idx);
 241         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 242 }
 243
 244
 245 static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
 246                                     struct sta_info *sta,
 247                                     struct ieee80211_key *old,
 248                                     struct ieee80211_key *new)
 249 {
 250         int idx, defkey, defmgmtkey;
 251
 252         if (new)
 253                 list_add(&new->list, &sdata->key_list);
 254
 255         if (sta) {
 256                 rcu_assign_pointer(sta->key, new);
 257         } else {
 258                 WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);
 259
 260                 if (old)
 261                         idx = old->conf.keyidx;
 262                 else
 263                         idx = new->conf.keyidx;
 264
 265                 defkey = old && sdata->default_key == old;
 266                 defmgmtkey = old && sdata->default_mgmt_key == old;
 267
 268                 if (defkey && !new)
 269                         __ieee80211_set_default_key(sdata, -1);
 270                 if (defmgmtkey && !new)
 271                         __ieee80211_set_default_mgmt_key(sdata, -1);
 272
 273                 rcu_assign_pointer(sdata->keys[idx], new);
 274                 if (defkey && new)
 275                         __ieee80211_set_default_key(sdata, new->conf.keyidx);
 276                 if (defmgmtkey && new)
 277                         __ieee80211_set_default_mgmt_key(sdata,
 278                                                          new->conf.keyidx);
 279         }
 280
 281         if (old) {
 282                 /*
 283                  * We'll use an empty list to indicate that the key
 284                  * has already been removed.
 285                  */
 286                 list_del_init(&old->list);
 287         }
 288 }
 289
 290 struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
 291                                           int idx,
 292                                           size_t key_len,
 293                                           const u8 *key_data)
 294 {
 295         struct ieee80211_key *key;
 296
 297         BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS);
 298
 299         key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
 300         if (!key)
 301                 return NULL;
 302
 303         /*
 304          * Default to software encryption; we'll later upload the
 305          * key to the hardware if possible.
 306          */
 307         key->conf.flags = 0;
 308         key->flags = 0;
 309
 310         key->conf.alg = alg;
 311         key->conf.keyidx = idx;
 312         key->conf.keylen = key_len;
 313         switch (alg) {
 314         case ALG_WEP:
 315                 key->conf.iv_len = WEP_IV_LEN;
 316                 key->conf.icv_len = WEP_ICV_LEN;
 317                 break;
 318         case ALG_TKIP:
 319                 key->conf.iv_len = TKIP_IV_LEN;
 320                 key->conf.icv_len = TKIP_ICV_LEN;
 321                 break;
 322         case ALG_CCMP:
 323                 key->conf.iv_len = CCMP_HDR_LEN;
 324                 key->conf.icv_len = CCMP_MIC_LEN;
 325                 break;
 326         case ALG_AES_CMAC:
 327                 key->conf.iv_len = 0;
 328                 key->conf.icv_len = sizeof(struct ieee80211_mmie);
 329                 break;
 330         }
 331         memcpy(key->conf.key, key_data, key_len);
 332         INIT_LIST_HEAD(&key->list);
 333         INIT_LIST_HEAD(&key->todo);
 334
 335         if (alg == ALG_CCMP) {
 336                 /*
 337                  * Initialize AES key state here as an optimization so that
 338                  * it does not need to be initialized for every packet.
 339                  */
 340                 key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
 341                 if (!key->u.ccmp.tfm) {
 342                         kfree(key);
 343                         return NULL;
 344                 }
 345         }
 346
 347         if (alg == ALG_AES_CMAC) {
 348                 /*
 349                  * Initialize AES key state here as an optimization so that
 350                  * it does not need to be initialized for every packet.
 351                  */
 352                 key->u.aes_cmac.tfm =
 353                         ieee80211_aes_cmac_key_setup(key_data);
 354                 if (!key->u.aes_cmac.tfm) {
 355                         kfree(key);
 356                         return NULL;
 357                 }
 358         }
 359
 360         return key;
 361 }
 362
 363 void ieee80211_key_link(struct ieee80211_key *key,
 364                         struct ieee80211_sub_if_data *sdata,
 365                         struct sta_info *sta)
 366 {
 367         struct ieee80211_key *old_key;
 368         unsigned long flags;
 369         int idx;
 370
 371         BUG_ON(!sdata);
 372         BUG_ON(!key);
 373
 374         idx = key->conf.keyidx;
 375         key->local = sdata->local;
 376         key->sdata = sdata;
 377         key->sta = sta;
 378
 379         if (sta) {
 380                 /*
 381                  * some hardware cannot handle TKIP with QoS, so
 382                  * we indicate whether QoS could be in use.
 383                  */
 384                 if (test_sta_flags(sta, WLAN_STA_WME))
 385                         key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
 386
 387                 /*
 388                  * This key is for a specific sta interface,
 389                  * inform the driver that it should try to store
 390                  * this key as pairwise key.
 391                  */
 392                 key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
 393         } else {
 394                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 395                         struct sta_info *ap;
 396
 397                         /*
 398                          * We're getting a sta pointer in,
 399                          * so must be under RCU read lock.
 400                          */
 401
 402                         /* same here, the AP could be using QoS */
 403                         ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
 404                         if (ap) {
 405                                 if (test_sta_flags(ap, WLAN_STA_WME))
 406                                         key->conf.flags |=
 407                                                 IEEE80211_KEY_FLAG_WMM_STA;
 408                         }
 409                 }
 410         }
 411
 412         spin_lock_irqsave(&sdata->local->key_lock, flags);
 413
 414         if (sta)
 415                 old_key = sta->key;
 416         else
 417                 old_key = sdata->keys[idx];
 418
 419         __ieee80211_key_replace(sdata, sta, old_key, key);
 420
 421         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 422
 423         /* free old key later */
 424         add_todo(old_key, KEY_FLAG_TODO_DELETE);
 425
 426         add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
 427         if (netif_running(sdata->dev))
 428                 add_todo(key, KEY_FLAG_TODO_HWACCEL_ADD);
 429 }
 430
 431 static void __ieee80211_key_free(struct ieee80211_key *key)
 432 {
 433         /*
 434          * Replace key with nothingness if it was ever used.
 435          */
 436         if (key->sdata)
 437                 __ieee80211_key_replace(key->sdata, key->sta,
 438                                         key, NULL);
 439
 440         add_todo(key, KEY_FLAG_TODO_DELETE);
 441 }
 442
 443 void ieee80211_key_free(struct ieee80211_key *key)
 444 {
 445         unsigned long flags;
 446
 447         if (!key)
 448                 return;
 449
 450         if (!key->sdata) {
 451                 /* The key has not been linked yet, simply free it
 452                  * and don't Oops */
 453                 if (key->conf.alg == ALG_CCMP)
 454                         ieee80211_aes_key_free(key->u.ccmp.tfm);
 455                 kfree(key);
 456                 return;
 457         }
 458
 459         spin_lock_irqsave(&key->sdata->local->key_lock, flags);
 460         __ieee80211_key_free(key);
 461         spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
 462 }
 463
 464 /*
 465  * To be safe against concurrent manipulations of the list (which shouldn't
 466  * actually happen) we need to hold the spinlock. But under the spinlock we
 467  * can't actually do much, so we defer processing to the todo list. Then run
 468  * the todo list to be sure the operation and possibly previously pending
 469  * operations are completed.
 470  */
 471 static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
 472                                         u32 todo_flags)
 473 {
 474         struct ieee80211_key *key;
 475         unsigned long flags;
 476
 477         might_sleep();
 478
 479         spin_lock_irqsave(&sdata->local->key_lock, flags);
 480         list_for_each_entry(key, &sdata->key_list, list)
 481                 add_todo(key, todo_flags);
 482         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 483
 484         ieee80211_key_todo();
 485 }
 486
 487 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
 488 {
 489         ASSERT_RTNL();
 490
 491         if (WARN_ON(!netif_running(sdata->dev)))
 492                 return;
 493
 494         ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_ADD);
 495 }
 496
 497 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
 498 {
 499         ASSERT_RTNL();
 500
 501         ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_REMOVE);
 502 }
 503
 504 static void __ieee80211_key_destroy(struct ieee80211_key *key)
 505 {
 506         if (!key)
 507                 return;
 508
 509         ieee80211_key_disable_hw_accel(key);
 510
 511         if (key->conf.alg == ALG_CCMP)
 512                 ieee80211_aes_key_free(key->u.ccmp.tfm);
 513         if (key->conf.alg == ALG_AES_CMAC)
 514                 ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
 515         ieee80211_debugfs_key_remove(key);
 516
 517         kfree(key);
 518 }
 519
 520 static void __ieee80211_key_todo(void)
 521 {
 522         struct ieee80211_key *key;
 523         bool work_done;
 524         u32 todoflags;
 525
 526         /*
 527          * NB: sta_info_destroy relies on this!
 528          */
 529         synchronize_rcu();
 530
 531         spin_lock(&todo_lock);
 532         while (!list_empty(&todo_list)) {
 533                 key = list_first_entry(&todo_list, struct ieee80211_key, todo);
 534                 list_del_init(&key->todo);
 535                 todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
 536                                           KEY_FLAG_TODO_DEFKEY |
 537                                           KEY_FLAG_TODO_DEFMGMTKEY |
 538                                           KEY_FLAG_TODO_HWACCEL_ADD |
 539                                           KEY_FLAG_TODO_HWACCEL_REMOVE |
 540                                           KEY_FLAG_TODO_DELETE);
 541                 key->flags &= ~todoflags;
 542                 spin_unlock(&todo_lock);
 543
 544                 work_done = false;
 545
 546                 if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
 547                         ieee80211_debugfs_key_add(key);
 548                         work_done = true;
 549                 }
 550                 if (todoflags & KEY_FLAG_TODO_DEFKEY) {
 551                         ieee80211_debugfs_key_remove_default(key->sdata);
 552                         ieee80211_debugfs_key_add_default(key->sdata);
 553                         work_done = true;
 554                 }
 555                 if (todoflags & KEY_FLAG_TODO_DEFMGMTKEY) {
 556                         ieee80211_debugfs_key_remove_mgmt_default(key->sdata);
 557                         ieee80211_debugfs_key_add_mgmt_default(key->sdata);
 558                         work_done = true;
 559                 }
 560                 if (todoflags & KEY_FLAG_TODO_HWACCEL_ADD) {
 561                         ieee80211_key_enable_hw_accel(key);
 562                         work_done = true;
 563                 }
 564                 if (todoflags & KEY_FLAG_TODO_HWACCEL_REMOVE) {
 565                         ieee80211_key_disable_hw_accel(key);
 566                         work_done = true;
 567                 }
 568                 if (todoflags & KEY_FLAG_TODO_DELETE) {
 569                         __ieee80211_key_destroy(key);
 570                         work_done = true;
 571                 }
 572
 573                 WARN_ON(!work_done);
 574
 575                 spin_lock(&todo_lock);
 576         }
 577         spin_unlock(&todo_lock);
 578 }
 579
 580 void ieee80211_key_todo(void)
 581 {
 582         ieee80211_key_lock();
 583         __ieee80211_key_todo();
 584         ieee80211_key_unlock();
 585 }
 586
 587 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 588 {
 589         struct ieee80211_key *key, *tmp;
 590         unsigned long flags;
 591
 592         ieee80211_key_lock();
 593
 594         ieee80211_debugfs_key_remove_default(sdata);
 595         ieee80211_debugfs_key_remove_mgmt_default(sdata);
 596
 597         spin_lock_irqsave(&sdata->local->key_lock, flags);
 598         list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
 599                 __ieee80211_key_free(key);
 600         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 601
 602         __ieee80211_key_todo();
 603
 604         ieee80211_key_unlock();
 605 }