linux/net/mac80211/key.c
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   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
  50static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  51
  52/* key mutex: used to synchronise todo runners */
  53static DEFINE_MUTEX(key_mutex);
  54static DEFINE_SPINLOCK(todo_lock);
  55static LIST_HEAD(todo_list);
  56
  57static void key_todo(struct work_struct *work)
  58{
  59        ieee80211_key_todo();
  60}
  61
  62static 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 */
  70static 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 */
  93static 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 */
 101static void ieee80211_key_unlock(void)
 102{
 103        mutex_unlock(&key_mutex);
 104}
 105
 106static void assert_key_lock(void)
 107{
 108        WARN_ON(!mutex_is_locked(&key_mutex));
 109}
 110
 111static 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
 119static 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
 155static 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
 196static 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
 210void 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
 219static 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
 234void 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
 245static 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
 290struct 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
 363void 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.mgd.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
 431static 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
 443void 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 */
 471static 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
 487void 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
 497void 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
 504static 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
 520static 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
 580void ieee80211_key_todo(void)
 581{
 582        ieee80211_key_lock();
 583        __ieee80211_key_todo();
 584        ieee80211_key_unlock();
 585}
 586
 587void 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}
 606