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 "driver-ops.h"
  20 #include "debugfs_key.h"
  21 #include "aes_ccm.h"
  22 #include "aes_cmac.h"
  23
  24
  25 /**
  26  * DOC: Key handling basics
  27  *
  28  * Key handling in mac80211 is done based on per-interface (sub_if_data)
  29  * keys and per-station keys. Since each station belongs to an interface,
  30  * each station key also belongs to that interface.
  31  *
  32  * Hardware acceleration is done on a best-effort basis, for each key
  33  * that is eligible the hardware is asked to enable that key but if
  34  * it cannot do that they key is simply kept for software encryption.
  35  * There is currently no way of knowing this except by looking into
  36  * debugfs.
  37  *
  38  * All key operations are protected internally so you can call them at
  39  * any time.
  40  *
  41  * Within mac80211, key references are, just as STA structure references,
  42  * protected by RCU. Note, however, that some things are unprotected,
  43  * namely the key->sta dereferences within the hardware acceleration
  44  * functions. This means that sta_info_destroy() must flush the key todo
  45  * list.
  46  *
  47  * All the direct key list manipulation functions must not sleep because
  48  * they can operate on STA info structs that are protected by RCU.
  49  */
  50
  51 static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  52
  53 /* key mutex: used to synchronise todo runners */
  54 static DEFINE_MUTEX(key_mutex);
  55 static DEFINE_SPINLOCK(todo_lock);
  56 static LIST_HEAD(todo_list);
  57
  58 static void key_todo(struct work_struct *work)
  59 {
  60         ieee80211_key_todo();
  61 }
  62
  63 static DECLARE_WORK(todo_work, key_todo);
  64
  65 /**
  66  * add_todo - add todo item for a key
  67  *
  68  * @key: key to add to do item for
  69  * @flag: todo flag(s)
  70  *
  71  * Must be called with IRQs or softirqs disabled.
  72  */
  73 static void add_todo(struct ieee80211_key *key, u32 flag)
  74 {
  75         if (!key)
  76                 return;
  77
  78         spin_lock(&todo_lock);
  79         key->flags |= flag;
  80         /*
  81          * Remove again if already on the list so that we move it to the end.
  82          */
  83         if (!list_empty(&key->todo))
  84                 list_del(&key->todo);
  85         list_add_tail(&key->todo, &todo_list);
  86         schedule_work(&todo_work);
  87         spin_unlock(&todo_lock);
  88 }
  89
  90 /**
  91  * ieee80211_key_lock - lock the mac80211 key operation lock
  92  *
  93  * This locks the (global) mac80211 key operation lock, all
  94  * key operations must be done under this lock.
  95  */
  96 static void ieee80211_key_lock(void)
  97 {
  98         mutex_lock(&key_mutex);
  99 }
 100
 101 /**
 102  * ieee80211_key_unlock - unlock the mac80211 key operation lock
 103  */
 104 static void ieee80211_key_unlock(void)
 105 {
 106         mutex_unlock(&key_mutex);
 107 }
 108
 109 static void assert_key_lock(void)
 110 {
 111         WARN_ON(!mutex_is_locked(&key_mutex));
 112 }
 113
 114 static struct ieee80211_sta *get_sta_for_key(struct ieee80211_key *key)
 115 {
 116         if (key->sta)
 117                 return &key->sta->sta;
 118
 119         return NULL;
 120 }
 121
 122 static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
 123 {
 124         struct ieee80211_sub_if_data *sdata;
 125         struct ieee80211_sta *sta;
 126         int ret;
 127
 128         assert_key_lock();
 129         might_sleep();
 130
 131         if (!key->local->ops->set_key)
 132                 return;
 133
 134         sta = get_sta_for_key(key);
 135
 136         sdata = key->sdata;
 137         if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 138                 sdata = container_of(sdata->bss,
 139                                      struct ieee80211_sub_if_data,
 140                                      u.ap);
 141
 142         ret = drv_set_key(key->local, SET_KEY, &sdata->vif, sta, &key->conf);
 143
 144         if (!ret) {
 145                 spin_lock_bh(&todo_lock);
 146                 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
 147                 spin_unlock_bh(&todo_lock);
 148         }
 149
 150         if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
 151                 printk(KERN_ERR "mac80211-%s: failed to set key "
 152                        "(%d, %pM) to hardware (%d)\n",
 153                        wiphy_name(key->local->hw.wiphy),
 154                        key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
 155 }
 156
 157 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
 158 {
 159         struct ieee80211_sub_if_data *sdata;
 160         struct ieee80211_sta *sta;
 161         int ret;
 162
 163         assert_key_lock();
 164         might_sleep();
 165
 166         if (!key || !key->local->ops->set_key)
 167                 return;
 168
 169         spin_lock_bh(&todo_lock);
 170         if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
 171                 spin_unlock_bh(&todo_lock);
 172                 return;
 173         }
 174         spin_unlock_bh(&todo_lock);
 175
 176         sta = get_sta_for_key(key);
 177         sdata = key->sdata;
 178
 179         if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 180                 sdata = container_of(sdata->bss,
 181                                      struct ieee80211_sub_if_data,
 182                                      u.ap);
 183
 184         ret = drv_set_key(key->local, DISABLE_KEY, &sdata->vif,
 185                           sta, &key->conf);
 186
 187         if (ret)
 188                 printk(KERN_ERR "mac80211-%s: failed to remove key "
 189                        "(%d, %pM) from hardware (%d)\n",
 190                        wiphy_name(key->local->hw.wiphy),
 191                        key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
 192
 193         spin_lock_bh(&todo_lock);
 194         key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
 195         spin_unlock_bh(&todo_lock);
 196 }
 197
 198 static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
 199                                         int idx)
 200 {
 201         struct ieee80211_key *key = NULL;
 202
 203         if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
 204                 key = sdata->keys[idx];
 205
 206         rcu_assign_pointer(sdata->default_key, key);
 207
 208         if (key)
 209                 add_todo(key, KEY_FLAG_TODO_DEFKEY);
 210 }
 211
 212 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
 213 {
 214         unsigned long flags;
 215
 216         spin_lock_irqsave(&sdata->local->key_lock, flags);
 217         __ieee80211_set_default_key(sdata, idx);
 218         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 219 }
 220
 221 static void
 222 __ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata, int idx)
 223 {
 224         struct ieee80211_key *key = NULL;
 225
 226         if (idx >= NUM_DEFAULT_KEYS &&
 227             idx < NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
 228                 key = sdata->keys[idx];
 229
 230         rcu_assign_pointer(sdata->default_mgmt_key, key);
 231
 232         if (key)
 233                 add_todo(key, KEY_FLAG_TODO_DEFMGMTKEY);
 234 }
 235
 236 void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
 237                                     int idx)
 238 {
 239         unsigned long flags;
 240
 241         spin_lock_irqsave(&sdata->local->key_lock, flags);
 242         __ieee80211_set_default_mgmt_key(sdata, idx);
 243         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 244 }
 245
 246
 247 static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
 248                                     struct sta_info *sta,
 249                                     struct ieee80211_key *old,
 250                                     struct ieee80211_key *new)
 251 {
 252         int idx, defkey, defmgmtkey;
 253
 254         if (new)
 255                 list_add(&new->list, &sdata->key_list);
 256
 257         if (sta) {
 258                 rcu_assign_pointer(sta->key, new);
 259         } else {
 260                 WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);
 261
 262                 if (old)
 263                         idx = old->conf.keyidx;
 264                 else
 265                         idx = new->conf.keyidx;
 266
 267                 defkey = old && sdata->default_key == old;
 268                 defmgmtkey = old && sdata->default_mgmt_key == old;
 269
 270                 if (defkey && !new)
 271                         __ieee80211_set_default_key(sdata, -1);
 272                 if (defmgmtkey && !new)
 273                         __ieee80211_set_default_mgmt_key(sdata, -1);
 274
 275                 rcu_assign_pointer(sdata->keys[idx], new);
 276                 if (defkey && new)
 277                         __ieee80211_set_default_key(sdata, new->conf.keyidx);
 278                 if (defmgmtkey && new)
 279                         __ieee80211_set_default_mgmt_key(sdata,
 280                                                          new->conf.keyidx);
 281         }
 282
 283         if (old) {
 284                 /*
 285                  * We'll use an empty list to indicate that the key
 286                  * has already been removed.
 287                  */
 288                 list_del_init(&old->list);
 289         }
 290 }
 291
 292 struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
 293                                           int idx,
 294                                           size_t key_len,
 295                                           const u8 *key_data,
 296                                           size_t seq_len, const u8 *seq)
 297 {
 298         struct ieee80211_key *key;
 299         int i, j;
 300
 301         BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS);
 302
 303         key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
 304         if (!key)
 305                 return NULL;
 306
 307         /*
 308          * Default to software encryption; we'll later upload the
 309          * key to the hardware if possible.
 310          */
 311         key->conf.flags = 0;
 312         key->flags = 0;
 313
 314         key->conf.alg = alg;
 315         key->conf.keyidx = idx;
 316         key->conf.keylen = key_len;
 317         switch (alg) {
 318         case ALG_WEP:
 319                 key->conf.iv_len = WEP_IV_LEN;
 320                 key->conf.icv_len = WEP_ICV_LEN;
 321                 break;
 322         case ALG_TKIP:
 323                 key->conf.iv_len = TKIP_IV_LEN;
 324                 key->conf.icv_len = TKIP_ICV_LEN;
 325                 if (seq) {
 326                         for (i = 0; i < NUM_RX_DATA_QUEUES; i++) {
 327                                 key->u.tkip.rx[i].iv32 =
 328                                         get_unaligned_le32(&seq[2]);
 329                                 key->u.tkip.rx[i].iv16 =
 330                                         get_unaligned_le16(seq);
 331                         }
 332                 }
 333                 break;
 334         case ALG_CCMP:
 335                 key->conf.iv_len = CCMP_HDR_LEN;
 336                 key->conf.icv_len = CCMP_MIC_LEN;
 337                 if (seq) {
 338                         for (i = 0; i < NUM_RX_DATA_QUEUES; i++)
 339                                 for (j = 0; j < CCMP_PN_LEN; j++)
 340                                         key->u.ccmp.rx_pn[i][j] =
 341                                                 seq[CCMP_PN_LEN - j - 1];
 342                 }
 343                 break;
 344         case ALG_AES_CMAC:
 345                 key->conf.iv_len = 0;
 346                 key->conf.icv_len = sizeof(struct ieee80211_mmie);
 347                 if (seq)
 348                         for (j = 0; j < 6; j++)
 349                                 key->u.aes_cmac.rx_pn[j] = seq[6 - j - 1];
 350                 break;
 351         }
 352         memcpy(key->conf.key, key_data, key_len);
 353         INIT_LIST_HEAD(&key->list);
 354         INIT_LIST_HEAD(&key->todo);
 355
 356         if (alg == ALG_CCMP) {
 357                 /*
 358                  * Initialize AES key state here as an optimization so that
 359                  * it does not need to be initialized for every packet.
 360                  */
 361                 key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
 362                 if (!key->u.ccmp.tfm) {
 363                         kfree(key);
 364                         return NULL;
 365                 }
 366         }
 367
 368         if (alg == ALG_AES_CMAC) {
 369                 /*
 370                  * Initialize AES key state here as an optimization so that
 371                  * it does not need to be initialized for every packet.
 372                  */
 373                 key->u.aes_cmac.tfm =
 374                         ieee80211_aes_cmac_key_setup(key_data);
 375                 if (!key->u.aes_cmac.tfm) {
 376                         kfree(key);
 377                         return NULL;
 378                 }
 379         }
 380
 381         return key;
 382 }
 383
 384 void ieee80211_key_link(struct ieee80211_key *key,
 385                         struct ieee80211_sub_if_data *sdata,
 386                         struct sta_info *sta)
 387 {
 388         struct ieee80211_key *old_key;
 389         unsigned long flags;
 390         int idx;
 391
 392         BUG_ON(!sdata);
 393         BUG_ON(!key);
 394
 395         idx = key->conf.keyidx;
 396         key->local = sdata->local;
 397         key->sdata = sdata;
 398         key->sta = sta;
 399
 400         if (sta) {
 401                 /*
 402                  * some hardware cannot handle TKIP with QoS, so
 403                  * we indicate whether QoS could be in use.
 404                  */
 405                 if (test_sta_flags(sta, WLAN_STA_WME))
 406                         key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
 407
 408                 /*
 409                  * This key is for a specific sta interface,
 410                  * inform the driver that it should try to store
 411                  * this key as pairwise key.
 412                  */
 413                 key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
 414         } else {
 415                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 416                         struct sta_info *ap;
 417
 418                         /*
 419                          * We're getting a sta pointer in,
 420                          * so must be under RCU read lock.
 421                          */
 422
 423                         /* same here, the AP could be using QoS */
 424                         ap = sta_info_get(key->local, key->sdata->u.mgd.bssid);
 425                         if (ap) {
 426                                 if (test_sta_flags(ap, WLAN_STA_WME))
 427                                         key->conf.flags |=
 428                                                 IEEE80211_KEY_FLAG_WMM_STA;
 429                         }
 430                 }
 431         }
 432
 433         spin_lock_irqsave(&sdata->local->key_lock, flags);
 434
 435         if (sta)
 436                 old_key = sta->key;
 437         else
 438                 old_key = sdata->keys[idx];
 439
 440         __ieee80211_key_replace(sdata, sta, old_key, key);
 441
 442         /* free old key later */
 443         add_todo(old_key, KEY_FLAG_TODO_DELETE);
 444
 445         add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
 446         if (netif_running(sdata->dev))
 447                 add_todo(key, KEY_FLAG_TODO_HWACCEL_ADD);
 448
 449         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 450 }
 451
 452 static void __ieee80211_key_free(struct ieee80211_key *key)
 453 {
 454         /*
 455          * Replace key with nothingness if it was ever used.
 456          */
 457         if (key->sdata)
 458                 __ieee80211_key_replace(key->sdata, key->sta,
 459                                         key, NULL);
 460
 461         add_todo(key, KEY_FLAG_TODO_DELETE);
 462 }
 463
 464 void ieee80211_key_free(struct ieee80211_key *key)
 465 {
 466         unsigned long flags;
 467
 468         if (!key)
 469                 return;
 470
 471         if (!key->sdata) {
 472                 /* The key has not been linked yet, simply free it
 473                  * and don't Oops */
 474                 if (key->conf.alg == ALG_CCMP)
 475                         ieee80211_aes_key_free(key->u.ccmp.tfm);
 476                 kfree(key);
 477                 return;
 478         }
 479
 480         spin_lock_irqsave(&key->sdata->local->key_lock, flags);
 481         __ieee80211_key_free(key);
 482         spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
 483 }
 484
 485 /*
 486  * To be safe against concurrent manipulations of the list (which shouldn't
 487  * actually happen) we need to hold the spinlock. But under the spinlock we
 488  * can't actually do much, so we defer processing to the todo list. Then run
 489  * the todo list to be sure the operation and possibly previously pending
 490  * operations are completed.
 491  */
 492 static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
 493                                         u32 todo_flags)
 494 {
 495         struct ieee80211_key *key;
 496         unsigned long flags;
 497
 498         might_sleep();
 499
 500         spin_lock_irqsave(&sdata->local->key_lock, flags);
 501         list_for_each_entry(key, &sdata->key_list, list)
 502                 add_todo(key, todo_flags);
 503         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 504
 505         ieee80211_key_todo();
 506 }
 507
 508 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
 509 {
 510         ASSERT_RTNL();
 511
 512         if (WARN_ON(!netif_running(sdata->dev)))
 513                 return;
 514
 515         ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_ADD);
 516 }
 517
 518 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
 519 {
 520         ASSERT_RTNL();
 521
 522         ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_REMOVE);
 523 }
 524
 525 static void __ieee80211_key_destroy(struct ieee80211_key *key)
 526 {
 527         if (!key)
 528                 return;
 529
 530         ieee80211_key_disable_hw_accel(key);
 531
 532         if (key->conf.alg == ALG_CCMP)
 533                 ieee80211_aes_key_free(key->u.ccmp.tfm);
 534         if (key->conf.alg == ALG_AES_CMAC)
 535                 ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
 536         ieee80211_debugfs_key_remove(key);
 537
 538         kfree(key);
 539 }
 540
 541 static void __ieee80211_key_todo(void)
 542 {
 543         struct ieee80211_key *key;
 544         bool work_done;
 545         u32 todoflags;
 546
 547         /*
 548          * NB: sta_info_destroy relies on this!
 549          */
 550         synchronize_rcu();
 551
 552         spin_lock_bh(&todo_lock);
 553         while (!list_empty(&todo_list)) {
 554                 key = list_first_entry(&todo_list, struct ieee80211_key, todo);
 555                 list_del_init(&key->todo);
 556                 todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
 557                                           KEY_FLAG_TODO_DEFKEY |
 558                                           KEY_FLAG_TODO_DEFMGMTKEY |
 559                                           KEY_FLAG_TODO_HWACCEL_ADD |
 560                                           KEY_FLAG_TODO_HWACCEL_REMOVE |
 561                                           KEY_FLAG_TODO_DELETE);
 562                 key->flags &= ~todoflags;
 563                 spin_unlock_bh(&todo_lock);
 564
 565                 work_done = false;
 566
 567                 if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
 568                         ieee80211_debugfs_key_add(key);
 569                         work_done = true;
 570                 }
 571                 if (todoflags & KEY_FLAG_TODO_DEFKEY) {
 572                         ieee80211_debugfs_key_remove_default(key->sdata);
 573                         ieee80211_debugfs_key_add_default(key->sdata);
 574                         work_done = true;
 575                 }
 576                 if (todoflags & KEY_FLAG_TODO_DEFMGMTKEY) {
 577                         ieee80211_debugfs_key_remove_mgmt_default(key->sdata);
 578                         ieee80211_debugfs_key_add_mgmt_default(key->sdata);
 579                         work_done = true;
 580                 }
 581                 if (todoflags & KEY_FLAG_TODO_HWACCEL_ADD) {
 582                         ieee80211_key_enable_hw_accel(key);
 583                         work_done = true;
 584                 }
 585                 if (todoflags & KEY_FLAG_TODO_HWACCEL_REMOVE) {
 586                         ieee80211_key_disable_hw_accel(key);
 587                         work_done = true;
 588                 }
 589                 if (todoflags & KEY_FLAG_TODO_DELETE) {
 590                         __ieee80211_key_destroy(key);
 591                         work_done = true;
 592                 }
 593
 594                 WARN_ON(!work_done);
 595
 596                 spin_lock_bh(&todo_lock);
 597         }
 598         spin_unlock_bh(&todo_lock);
 599 }
 600
 601 void ieee80211_key_todo(void)
 602 {
 603         ieee80211_key_lock();
 604         __ieee80211_key_todo();
 605         ieee80211_key_unlock();
 606 }
 607
 608 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 609 {
 610         struct ieee80211_key *key, *tmp;
 611         unsigned long flags;
 612
 613         ieee80211_key_lock();
 614
 615         ieee80211_debugfs_key_remove_default(sdata);
 616         ieee80211_debugfs_key_remove_mgmt_default(sdata);
 617
 618         spin_lock_irqsave(&sdata->local->key_lock, flags);
 619         list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
 620                 __ieee80211_key_free(key);
 621         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 622
 623         __ieee80211_key_todo();
 624
 625         ieee80211_key_unlock();
 626 }