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 <linux/slab.h>
  18 #include <net/mac80211.h>
  19 #include "ieee80211_i.h"
  20 #include "driver-ops.h"
  21 #include "debugfs_key.h"
  22 #include "aes_ccm.h"
  23 #include "aes_cmac.h"
  24
  25
  26 /**
  27  * DOC: Key handling basics
  28  *
  29  * Key handling in mac80211 is done based on per-interface (sub_if_data)
  30  * keys and per-station keys. Since each station belongs to an interface,
  31  * each station key also belongs to that interface.
  32  *
  33  * Hardware acceleration is done on a best-effort basis, for each key
  34  * that is eligible the hardware is asked to enable that key but if
  35  * it cannot do that they key is simply kept for software encryption.
  36  * There is currently no way of knowing this except by looking into
  37  * debugfs.
  38  *
  39  * All key operations are protected internally so you can call them at
  40  * any time.
  41  *
  42  * Within mac80211, key references are, just as STA structure references,
  43  * protected by RCU. Note, however, that some things are unprotected,
  44  * namely the key->sta dereferences within the hardware acceleration
  45  * functions. This means that sta_info_destroy() must flush the key todo
  46  * list.
  47  *
  48  * All the direct key list manipulation functions must not sleep because
  49  * they can operate on STA info structs that are protected by RCU.
  50  */
  51
  52 static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  53
  54 /* key mutex: used to synchronise todo runners */
  55 static DEFINE_MUTEX(key_mutex);
  56 static DEFINE_SPINLOCK(todo_lock);
  57 static LIST_HEAD(todo_list);
  58
  59 static void key_todo(struct work_struct *work)
  60 {
  61         ieee80211_key_todo();
  62 }
  63
  64 static DECLARE_WORK(todo_work, key_todo);
  65
  66 /**
  67  * add_todo - add todo item for a key
  68  *
  69  * @key: key to add to do item for
  70  * @flag: todo flag(s)
  71  *
  72  * Must be called with IRQs or softirqs disabled.
  73  */
  74 static void add_todo(struct ieee80211_key *key, u32 flag)
  75 {
  76         if (!key)
  77                 return;
  78
  79         spin_lock(&todo_lock);
  80         key->flags |= flag;
  81         /*
  82          * Remove again if already on the list so that we move it to the end.
  83          */
  84         if (!list_empty(&key->todo))
  85                 list_del(&key->todo);
  86         list_add_tail(&key->todo, &todo_list);
  87         schedule_work(&todo_work);
  88         spin_unlock(&todo_lock);
  89 }
  90
  91 /**
  92  * ieee80211_key_lock - lock the mac80211 key operation lock
  93  *
  94  * This locks the (global) mac80211 key operation lock, all
  95  * key operations must be done under this lock.
  96  */
  97 static void ieee80211_key_lock(void)
  98 {
  99         mutex_lock(&key_mutex);
 100 }
 101
 102 /**
 103  * ieee80211_key_unlock - unlock the mac80211 key operation lock
 104  */
 105 static void ieee80211_key_unlock(void)
 106 {
 107         mutex_unlock(&key_mutex);
 108 }
 109
 110 static void assert_key_lock(void)
 111 {
 112         WARN_ON(!mutex_is_locked(&key_mutex));
 113 }
 114
 115 static struct ieee80211_sta *get_sta_for_key(struct ieee80211_key *key)
 116 {
 117         if (key->sta)
 118                 return &key->sta->sta;
 119
 120         return NULL;
 121 }
 122
 123 static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
 124 {
 125         struct ieee80211_sub_if_data *sdata;
 126         struct ieee80211_sta *sta;
 127         int ret;
 128
 129         assert_key_lock();
 130         might_sleep();
 131
 132         if (!key->local->ops->set_key)
 133                 return;
 134
 135         sta = get_sta_for_key(key);
 136
 137         sdata = key->sdata;
 138         if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 139                 sdata = container_of(sdata->bss,
 140                                      struct ieee80211_sub_if_data,
 141                                      u.ap);
 142
 143         ret = drv_set_key(key->local, SET_KEY, sdata, sta, &key->conf);
 144
 145         if (!ret) {
 146                 spin_lock_bh(&todo_lock);
 147                 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
 148                 spin_unlock_bh(&todo_lock);
 149         }
 150
 151         if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
 152                 printk(KERN_ERR "mac80211-%s: failed to set key "
 153                        "(%d, %pM) to hardware (%d)\n",
 154                        wiphy_name(key->local->hw.wiphy),
 155                        key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
 156 }
 157
 158 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
 159 {
 160         struct ieee80211_sub_if_data *sdata;
 161         struct ieee80211_sta *sta;
 162         int ret;
 163
 164         assert_key_lock();
 165         might_sleep();
 166
 167         if (!key || !key->local->ops->set_key)
 168                 return;
 169
 170         spin_lock_bh(&todo_lock);
 171         if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
 172                 spin_unlock_bh(&todo_lock);
 173                 return;
 174         }
 175         spin_unlock_bh(&todo_lock);
 176
 177         sta = get_sta_for_key(key);
 178         sdata = key->sdata;
 179
 180         if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 181                 sdata = container_of(sdata->bss,
 182                                      struct ieee80211_sub_if_data,
 183                                      u.ap);
 184
 185         ret = drv_set_key(key->local, DISABLE_KEY, sdata,
 186                           sta, &key->conf);
 187
 188         if (ret)
 189                 printk(KERN_ERR "mac80211-%s: failed to remove key "
 190                        "(%d, %pM) from hardware (%d)\n",
 191                        wiphy_name(key->local->hw.wiphy),
 192                        key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
 193
 194         spin_lock_bh(&todo_lock);
 195         key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
 196         spin_unlock_bh(&todo_lock);
 197 }
 198
 199 static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
 200                                         int idx)
 201 {
 202         struct ieee80211_key *key = NULL;
 203
 204         if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
 205                 key = sdata->keys[idx];
 206
 207         rcu_assign_pointer(sdata->default_key, key);
 208
 209         if (key)
 210                 add_todo(key, KEY_FLAG_TODO_DEFKEY);
 211 }
 212
 213 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
 214 {
 215         unsigned long flags;
 216
 217         spin_lock_irqsave(&sdata->local->key_lock, flags);
 218         __ieee80211_set_default_key(sdata, idx);
 219         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 220 }
 221
 222 static void
 223 __ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata, int idx)
 224 {
 225         struct ieee80211_key *key = NULL;
 226
 227         if (idx >= NUM_DEFAULT_KEYS &&
 228             idx < NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
 229                 key = sdata->keys[idx];
 230
 231         rcu_assign_pointer(sdata->default_mgmt_key, key);
 232
 233         if (key)
 234                 add_todo(key, KEY_FLAG_TODO_DEFMGMTKEY);
 235 }
 236
 237 void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
 238                                     int idx)
 239 {
 240         unsigned long flags;
 241
 242         spin_lock_irqsave(&sdata->local->key_lock, flags);
 243         __ieee80211_set_default_mgmt_key(sdata, idx);
 244         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 245 }
 246
 247
 248 static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
 249                                     struct sta_info *sta,
 250                                     struct ieee80211_key *old,
 251                                     struct ieee80211_key *new)
 252 {
 253         int idx, defkey, defmgmtkey;
 254
 255         if (new)
 256                 list_add(&new->list, &sdata->key_list);
 257
 258         if (sta) {
 259                 rcu_assign_pointer(sta->key, new);
 260         } else {
 261                 WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);
 262
 263                 if (old)
 264                         idx = old->conf.keyidx;
 265                 else
 266                         idx = new->conf.keyidx;
 267
 268                 defkey = old && sdata->default_key == old;
 269                 defmgmtkey = old && sdata->default_mgmt_key == old;
 270
 271                 if (defkey && !new)
 272                         __ieee80211_set_default_key(sdata, -1);
 273                 if (defmgmtkey && !new)
 274                         __ieee80211_set_default_mgmt_key(sdata, -1);
 275
 276                 rcu_assign_pointer(sdata->keys[idx], new);
 277                 if (defkey && new)
 278                         __ieee80211_set_default_key(sdata, new->conf.keyidx);
 279                 if (defmgmtkey && new)
 280                         __ieee80211_set_default_mgmt_key(sdata,
 281                                                          new->conf.keyidx);
 282         }
 283
 284         if (old) {
 285                 /*
 286                  * We'll use an empty list to indicate that the key
 287                  * has already been removed.
 288                  */
 289                 list_del_init(&old->list);
 290         }
 291 }
 292
 293 struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
 294                                           int idx,
 295                                           size_t key_len,
 296                                           const u8 *key_data,
 297                                           size_t seq_len, const u8 *seq)
 298 {
 299         struct ieee80211_key *key;
 300         int i, j;
 301
 302         BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS);
 303
 304         key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
 305         if (!key)
 306                 return NULL;
 307
 308         /*
 309          * Default to software encryption; we'll later upload the
 310          * key to the hardware if possible.
 311          */
 312         key->conf.flags = 0;
 313         key->flags = 0;
 314
 315         key->conf.alg = alg;
 316         key->conf.keyidx = idx;
 317         key->conf.keylen = key_len;
 318         switch (alg) {
 319         case ALG_WEP:
 320                 key->conf.iv_len = WEP_IV_LEN;
 321                 key->conf.icv_len = WEP_ICV_LEN;
 322                 break;
 323         case ALG_TKIP:
 324                 key->conf.iv_len = TKIP_IV_LEN;
 325                 key->conf.icv_len = TKIP_ICV_LEN;
 326                 if (seq) {
 327                         for (i = 0; i < NUM_RX_DATA_QUEUES; i++) {
 328                                 key->u.tkip.rx[i].iv32 =
 329                                         get_unaligned_le32(&seq[2]);
 330                                 key->u.tkip.rx[i].iv16 =
 331                                         get_unaligned_le16(seq);
 332                         }
 333                 }
 334                 break;
 335         case ALG_CCMP:
 336                 key->conf.iv_len = CCMP_HDR_LEN;
 337                 key->conf.icv_len = CCMP_MIC_LEN;
 338                 if (seq) {
 339                         for (i = 0; i < NUM_RX_DATA_QUEUES; i++)
 340                                 for (j = 0; j < CCMP_PN_LEN; j++)
 341                                         key->u.ccmp.rx_pn[i][j] =
 342                                                 seq[CCMP_PN_LEN - j - 1];
 343                 }
 344                 break;
 345         case ALG_AES_CMAC:
 346                 key->conf.iv_len = 0;
 347                 key->conf.icv_len = sizeof(struct ieee80211_mmie);
 348                 if (seq)
 349                         for (j = 0; j < 6; j++)
 350                                 key->u.aes_cmac.rx_pn[j] = seq[6 - j - 1];
 351                 break;
 352         }
 353         memcpy(key->conf.key, key_data, key_len);
 354         INIT_LIST_HEAD(&key->list);
 355         INIT_LIST_HEAD(&key->todo);
 356
 357         if (alg == ALG_CCMP) {
 358                 /*
 359                  * Initialize AES key state here as an optimization so that
 360                  * it does not need to be initialized for every packet.
 361                  */
 362                 key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
 363                 if (!key->u.ccmp.tfm) {
 364                         kfree(key);
 365                         return NULL;
 366                 }
 367         }
 368
 369         if (alg == ALG_AES_CMAC) {
 370                 /*
 371                  * Initialize AES key state here as an optimization so that
 372                  * it does not need to be initialized for every packet.
 373                  */
 374                 key->u.aes_cmac.tfm =
 375                         ieee80211_aes_cmac_key_setup(key_data);
 376                 if (!key->u.aes_cmac.tfm) {
 377                         kfree(key);
 378                         return NULL;
 379                 }
 380         }
 381
 382         return key;
 383 }
 384
 385 void ieee80211_key_link(struct ieee80211_key *key,
 386                         struct ieee80211_sub_if_data *sdata,
 387                         struct sta_info *sta)
 388 {
 389         struct ieee80211_key *old_key;
 390         unsigned long flags;
 391         int idx;
 392
 393         BUG_ON(!sdata);
 394         BUG_ON(!key);
 395
 396         idx = key->conf.keyidx;
 397         key->local = sdata->local;
 398         key->sdata = sdata;
 399         key->sta = sta;
 400
 401         if (sta) {
 402                 /*
 403                  * some hardware cannot handle TKIP with QoS, so
 404                  * we indicate whether QoS could be in use.
 405                  */
 406                 if (test_sta_flags(sta, WLAN_STA_WME))
 407                         key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
 408
 409                 /*
 410                  * This key is for a specific sta interface,
 411                  * inform the driver that it should try to store
 412                  * this key as pairwise key.
 413                  */
 414                 key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
 415         } else {
 416                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 417                         struct sta_info *ap;
 418
 419                         /*
 420                          * We're getting a sta pointer in,
 421                          * so must be under RCU read lock.
 422                          */
 423
 424                         /* same here, the AP could be using QoS */
 425                         ap = sta_info_get(key->sdata, key->sdata->u.mgd.bssid);
 426                         if (ap) {
 427                                 if (test_sta_flags(ap, WLAN_STA_WME))
 428                                         key->conf.flags |=
 429                                                 IEEE80211_KEY_FLAG_WMM_STA;
 430                         }
 431                 }
 432         }
 433
 434         spin_lock_irqsave(&sdata->local->key_lock, flags);
 435
 436         if (sta)
 437                 old_key = sta->key;
 438         else
 439                 old_key = sdata->keys[idx];
 440
 441         __ieee80211_key_replace(sdata, sta, old_key, key);
 442
 443         /* free old key later */
 444         add_todo(old_key, KEY_FLAG_TODO_DELETE);
 445
 446         add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
 447         if (ieee80211_sdata_running(sdata))
 448                 add_todo(key, KEY_FLAG_TODO_HWACCEL_ADD);
 449
 450         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 451 }
 452
 453 static void __ieee80211_key_free(struct ieee80211_key *key)
 454 {
 455         /*
 456          * Replace key with nothingness if it was ever used.
 457          */
 458         if (key->sdata)
 459                 __ieee80211_key_replace(key->sdata, key->sta,
 460                                         key, NULL);
 461
 462         add_todo(key, KEY_FLAG_TODO_DELETE);
 463 }
 464
 465 void ieee80211_key_free(struct ieee80211_key *key)
 466 {
 467         unsigned long flags;
 468
 469         if (!key)
 470                 return;
 471
 472         if (!key->sdata) {
 473                 /* The key has not been linked yet, simply free it
 474                  * and don't Oops */
 475                 if (key->conf.alg == ALG_CCMP)
 476                         ieee80211_aes_key_free(key->u.ccmp.tfm);
 477                 kfree(key);
 478                 return;
 479         }
 480
 481         spin_lock_irqsave(&key->sdata->local->key_lock, flags);
 482         __ieee80211_key_free(key);
 483         spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
 484 }
 485
 486 /*
 487  * To be safe against concurrent manipulations of the list (which shouldn't
 488  * actually happen) we need to hold the spinlock. But under the spinlock we
 489  * can't actually do much, so we defer processing to the todo list. Then run
 490  * the todo list to be sure the operation and possibly previously pending
 491  * operations are completed.
 492  */
 493 static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
 494                                         u32 todo_flags)
 495 {
 496         struct ieee80211_key *key;
 497         unsigned long flags;
 498
 499         might_sleep();
 500
 501         spin_lock_irqsave(&sdata->local->key_lock, flags);
 502         list_for_each_entry(key, &sdata->key_list, list)
 503                 add_todo(key, todo_flags);
 504         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 505
 506         ieee80211_key_todo();
 507 }
 508
 509 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
 510 {
 511         ASSERT_RTNL();
 512
 513         if (WARN_ON(!ieee80211_sdata_running(sdata)))
 514                 return;
 515
 516         ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_ADD);
 517 }
 518
 519 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
 520 {
 521         ASSERT_RTNL();
 522
 523         ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_REMOVE);
 524 }
 525
 526 static void __ieee80211_key_destroy(struct ieee80211_key *key)
 527 {
 528         if (!key)
 529                 return;
 530
 531         ieee80211_key_disable_hw_accel(key);
 532
 533         if (key->conf.alg == ALG_CCMP)
 534                 ieee80211_aes_key_free(key->u.ccmp.tfm);
 535         if (key->conf.alg == ALG_AES_CMAC)
 536                 ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
 537         ieee80211_debugfs_key_remove(key);
 538
 539         kfree(key);
 540 }
 541
 542 static void __ieee80211_key_todo(void)
 543 {
 544         struct ieee80211_key *key;
 545         bool work_done;
 546         u32 todoflags;
 547
 548         /*
 549          * NB: sta_info_destroy relies on this!
 550          */
 551         synchronize_rcu();
 552
 553         spin_lock_bh(&todo_lock);
 554         while (!list_empty(&todo_list)) {
 555                 key = list_first_entry(&todo_list, struct ieee80211_key, todo);
 556                 list_del_init(&key->todo);
 557                 todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
 558                                           KEY_FLAG_TODO_DEFKEY |
 559                                           KEY_FLAG_TODO_DEFMGMTKEY |
 560                                           KEY_FLAG_TODO_HWACCEL_ADD |
 561                                           KEY_FLAG_TODO_HWACCEL_REMOVE |
 562                                           KEY_FLAG_TODO_DELETE);
 563                 key->flags &= ~todoflags;
 564                 spin_unlock_bh(&todo_lock);
 565
 566                 work_done = false;
 567
 568                 if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
 569                         ieee80211_debugfs_key_add(key);
 570                         work_done = true;
 571                 }
 572                 if (todoflags & KEY_FLAG_TODO_DEFKEY) {
 573                         ieee80211_debugfs_key_remove_default(key->sdata);
 574                         ieee80211_debugfs_key_add_default(key->sdata);
 575                         work_done = true;
 576                 }
 577                 if (todoflags & KEY_FLAG_TODO_DEFMGMTKEY) {
 578                         ieee80211_debugfs_key_remove_mgmt_default(key->sdata);
 579                         ieee80211_debugfs_key_add_mgmt_default(key->sdata);
 580                         work_done = true;
 581                 }
 582                 if (todoflags & KEY_FLAG_TODO_HWACCEL_ADD) {
 583                         ieee80211_key_enable_hw_accel(key);
 584                         work_done = true;
 585                 }
 586                 if (todoflags & KEY_FLAG_TODO_HWACCEL_REMOVE) {
 587                         ieee80211_key_disable_hw_accel(key);
 588                         work_done = true;
 589                 }
 590                 if (todoflags & KEY_FLAG_TODO_DELETE) {
 591                         __ieee80211_key_destroy(key);
 592                         work_done = true;
 593                 }
 594
 595                 WARN_ON(!work_done);
 596
 597                 spin_lock_bh(&todo_lock);
 598         }
 599         spin_unlock_bh(&todo_lock);
 600 }
 601
 602 void ieee80211_key_todo(void)
 603 {
 604         ieee80211_key_lock();
 605         __ieee80211_key_todo();
 606         ieee80211_key_unlock();
 607 }
 608
 609 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 610 {
 611         struct ieee80211_key *key, *tmp;
 612         unsigned long flags;
 613
 614         ieee80211_key_lock();
 615
 616         ieee80211_debugfs_key_remove_default(sdata);
 617         ieee80211_debugfs_key_remove_mgmt_default(sdata);
 618
 619         spin_lock_irqsave(&sdata->local->key_lock, flags);
 620         list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
 621                 __ieee80211_key_free(key);
 622         spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 623
 624         __ieee80211_key_todo();
 625
 626         ieee80211_key_unlock();
 627 }