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
key_todo(struct work_struct * work)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 */
add_todo(struct ieee80211_key * key,u32 flag)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 */
ieee80211_key_lock(void)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 */
ieee80211_key_unlock(void)101 static void ieee80211_key_unlock(void)
102 {
103 mutex_unlock(&key_mutex);
104 }
105
assert_key_lock(void)106 static void assert_key_lock(void)
107 {
108 WARN_ON(!mutex_is_locked(&key_mutex));
109 }
110
get_mac_for_key(struct ieee80211_key * key)111 static const u8 *get_mac_for_key(struct ieee80211_key *key)
112 {
113 const u8 *addr = bcast_addr;
114
115 /*
116 * If we're an AP we won't ever receive frames with a non-WEP
117 * group key so we tell the driver that by using the zero MAC
118 * address to indicate a transmit-only key.
119 */
120 if (key->conf.alg != ALG_WEP &&
121 (key->sdata->vif.type == NL80211_IFTYPE_AP ||
122 key->sdata->vif.type == NL80211_IFTYPE_AP_VLAN))
123 addr = zero_addr;
124
125 if (key->sta)
126 addr = key->sta->sta.addr;
127
128 return addr;
129 }
130
ieee80211_key_enable_hw_accel(struct ieee80211_key * key)131 static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
132 {
133 const u8 *addr;
134 int ret;
135
136 assert_key_lock();
137 might_sleep();
138
139 if (!key->local->ops->set_key)
140 return;
141
142 addr = get_mac_for_key(key);
143
144 ret = key->local->ops->set_key(local_to_hw(key->local), SET_KEY,
145 key->sdata->dev->dev_addr, addr,
146 &key->conf);
147
148 if (!ret) {
149 spin_lock(&todo_lock);
150 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
151 spin_unlock(&todo_lock);
152 }
153
154 if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
155 printk(KERN_ERR "mac80211-%s: failed to set key "
156 "(%d, %pM) to hardware (%d)\n",
157 wiphy_name(key->local->hw.wiphy),
158 key->conf.keyidx, addr, ret);
159 }
160
ieee80211_key_disable_hw_accel(struct ieee80211_key * key)161 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
162 {
163 const u8 *addr;
164 int ret;
165
166 assert_key_lock();
167 might_sleep();
168
169 if (!key || !key->local->ops->set_key)
170 return;
171
172 spin_lock(&todo_lock);
173 if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
174 spin_unlock(&todo_lock);
175 return;
176 }
177 spin_unlock(&todo_lock);
178
179 addr = get_mac_for_key(key);
180
181 ret = key->local->ops->set_key(local_to_hw(key->local), DISABLE_KEY,
182 key->sdata->dev->dev_addr, addr,
183 &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, addr, ret);
190
191 spin_lock(&todo_lock);
192 key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
193 spin_unlock(&todo_lock);
194 }
195
__ieee80211_set_default_key(struct ieee80211_sub_if_data * sdata,int idx)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
ieee80211_set_default_key(struct ieee80211_sub_if_data * sdata,int idx)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
__ieee80211_key_replace(struct ieee80211_sub_if_data * sdata,struct sta_info * sta,struct ieee80211_key * old,struct ieee80211_key * new)220 static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
221 struct sta_info *sta,
222 struct ieee80211_key *old,
223 struct ieee80211_key *new)
224 {
225 int idx, defkey;
226
227 if (new)
228 list_add(&new->list, &sdata->key_list);
229
230 if (sta) {
231 rcu_assign_pointer(sta->key, new);
232 } else {
233 WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);
234
235 if (old)
236 idx = old->conf.keyidx;
237 else
238 idx = new->conf.keyidx;
239
240 defkey = old && sdata->default_key == old;
241
242 if (defkey && !new)
243 __ieee80211_set_default_key(sdata, -1);
244
245 rcu_assign_pointer(sdata->keys[idx], new);
246 if (defkey && new)
247 __ieee80211_set_default_key(sdata, new->conf.keyidx);
248 }
249
250 if (old) {
251 /*
252 * We'll use an empty list to indicate that the key
253 * has already been removed.
254 */
255 list_del_init(&old->list);
256 }
257 }
258
ieee80211_key_alloc(enum ieee80211_key_alg alg,int idx,size_t key_len,const u8 * key_data)259 struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
260 int idx,
261 size_t key_len,
262 const u8 *key_data)
263 {
264 struct ieee80211_key *key;
265
266 BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS);
267
268 key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
269 if (!key)
270 return NULL;
271
272 /*
273 * Default to software encryption; we'll later upload the
274 * key to the hardware if possible.
275 */
276 key->conf.flags = 0;
277 key->flags = 0;
278
279 key->conf.alg = alg;
280 key->conf.keyidx = idx;
281 key->conf.keylen = key_len;
282 switch (alg) {
283 case ALG_WEP:
284 key->conf.iv_len = WEP_IV_LEN;
285 key->conf.icv_len = WEP_ICV_LEN;
286 break;
287 case ALG_TKIP:
288 key->conf.iv_len = TKIP_IV_LEN;
289 key->conf.icv_len = TKIP_ICV_LEN;
290 break;
291 case ALG_CCMP:
292 key->conf.iv_len = CCMP_HDR_LEN;
293 key->conf.icv_len = CCMP_MIC_LEN;
294 break;
295 }
296 memcpy(key->conf.key, key_data, key_len);
297 INIT_LIST_HEAD(&key->list);
298 INIT_LIST_HEAD(&key->todo);
299
300 if (alg == ALG_CCMP) {
301 /*
302 * Initialize AES key state here as an optimization so that
303 * it does not need to be initialized for every packet.
304 */
305 key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
306 if (!key->u.ccmp.tfm) {
307 kfree(key);
308 return NULL;
309 }
310 }
311
312 return key;
313 }
314
ieee80211_key_link(struct ieee80211_key * key,struct ieee80211_sub_if_data * sdata,struct sta_info * sta)315 void ieee80211_key_link(struct ieee80211_key *key,
316 struct ieee80211_sub_if_data *sdata,
317 struct sta_info *sta)
318 {
319 struct ieee80211_key *old_key;
320 unsigned long flags;
321 int idx;
322
323 BUG_ON(!sdata);
324 BUG_ON(!key);
325
326 idx = key->conf.keyidx;
327 key->local = sdata->local;
328 key->sdata = sdata;
329 key->sta = sta;
330
331 if (sta) {
332 /*
333 * some hardware cannot handle TKIP with QoS, so
334 * we indicate whether QoS could be in use.
335 */
336 if (test_sta_flags(sta, WLAN_STA_WME))
337 key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
338
339 /*
340 * This key is for a specific sta interface,
341 * inform the driver that it should try to store
342 * this key as pairwise key.
343 */
344 key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
345 } else {
346 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
347 struct sta_info *ap;
348
349 /*
350 * We're getting a sta pointer in,
351 * so must be under RCU read lock.
352 */
353
354 /* same here, the AP could be using QoS */
355 ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
356 if (ap) {
357 if (test_sta_flags(ap, WLAN_STA_WME))
358 key->conf.flags |=
359 IEEE80211_KEY_FLAG_WMM_STA;
360 }
361 }
362 }
363
364 spin_lock_irqsave(&sdata->local->key_lock, flags);
365
366 if (sta)
367 old_key = sta->key;
368 else
369 old_key = sdata->keys[idx];
370
371 __ieee80211_key_replace(sdata, sta, old_key, key);
372
373 spin_unlock_irqrestore(&sdata->local->key_lock, flags);
374
375 /* free old key later */
376 add_todo(old_key, KEY_FLAG_TODO_DELETE);
377
378 add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
379 if (netif_running(sdata->dev))
380 add_todo(key, KEY_FLAG_TODO_HWACCEL_ADD);
381 }
382
__ieee80211_key_free(struct ieee80211_key * key)383 static void __ieee80211_key_free(struct ieee80211_key *key)
384 {
385 /*
386 * Replace key with nothingness if it was ever used.
387 */
388 if (key->sdata)
389 __ieee80211_key_replace(key->sdata, key->sta,
390 key, NULL);
391
392 add_todo(key, KEY_FLAG_TODO_DELETE);
393 }
394
ieee80211_key_free(struct ieee80211_key * key)395 void ieee80211_key_free(struct ieee80211_key *key)
396 {
397 unsigned long flags;
398
399 if (!key)
400 return;
401
402 if (!key->sdata) {
403 /* The key has not been linked yet, simply free it
404 * and don't Oops */
405 if (key->conf.alg == ALG_CCMP)
406 ieee80211_aes_key_free(key->u.ccmp.tfm);
407 kfree(key);
408 return;
409 }
410
411 spin_lock_irqsave(&key->sdata->local->key_lock, flags);
412 __ieee80211_key_free(key);
413 spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
414 }
415
416 /*
417 * To be safe against concurrent manipulations of the list (which shouldn't
418 * actually happen) we need to hold the spinlock. But under the spinlock we
419 * can't actually do much, so we defer processing to the todo list. Then run
420 * the todo list to be sure the operation and possibly previously pending
421 * operations are completed.
422 */
ieee80211_todo_for_each_key(struct ieee80211_sub_if_data * sdata,u32 todo_flags)423 static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
424 u32 todo_flags)
425 {
426 struct ieee80211_key *key;
427 unsigned long flags;
428
429 might_sleep();
430
431 spin_lock_irqsave(&sdata->local->key_lock, flags);
432 list_for_each_entry(key, &sdata->key_list, list)
433 add_todo(key, todo_flags);
434 spin_unlock_irqrestore(&sdata->local->key_lock, flags);
435
436 ieee80211_key_todo();
437 }
438
ieee80211_enable_keys(struct ieee80211_sub_if_data * sdata)439 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
440 {
441 ASSERT_RTNL();
442
443 if (WARN_ON(!netif_running(sdata->dev)))
444 return;
445
446 ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_ADD);
447 }
448
ieee80211_disable_keys(struct ieee80211_sub_if_data * sdata)449 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
450 {
451 ASSERT_RTNL();
452
453 ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_REMOVE);
454 }
455
__ieee80211_key_destroy(struct ieee80211_key * key)456 static void __ieee80211_key_destroy(struct ieee80211_key *key)
457 {
458 if (!key)
459 return;
460
461 ieee80211_key_disable_hw_accel(key);
462
463 if (key->conf.alg == ALG_CCMP)
464 ieee80211_aes_key_free(key->u.ccmp.tfm);
465 ieee80211_debugfs_key_remove(key);
466
467 kfree(key);
468 }
469
__ieee80211_key_todo(void)470 static void __ieee80211_key_todo(void)
471 {
472 struct ieee80211_key *key;
473 bool work_done;
474 u32 todoflags;
475
476 /*
477 * NB: sta_info_destroy relies on this!
478 */
479 synchronize_rcu();
480
481 spin_lock(&todo_lock);
482 while (!list_empty(&todo_list)) {
483 key = list_first_entry(&todo_list, struct ieee80211_key, todo);
484 list_del_init(&key->todo);
485 todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
486 KEY_FLAG_TODO_DEFKEY |
487 KEY_FLAG_TODO_HWACCEL_ADD |
488 KEY_FLAG_TODO_HWACCEL_REMOVE |
489 KEY_FLAG_TODO_DELETE);
490 key->flags &= ~todoflags;
491 spin_unlock(&todo_lock);
492
493 work_done = false;
494
495 if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
496 ieee80211_debugfs_key_add(key);
497 work_done = true;
498 }
499 if (todoflags & KEY_FLAG_TODO_DEFKEY) {
500 ieee80211_debugfs_key_remove_default(key->sdata);
501 ieee80211_debugfs_key_add_default(key->sdata);
502 work_done = true;
503 }
504 if (todoflags & KEY_FLAG_TODO_HWACCEL_ADD) {
505 ieee80211_key_enable_hw_accel(key);
506 work_done = true;
507 }
508 if (todoflags & KEY_FLAG_TODO_HWACCEL_REMOVE) {
509 ieee80211_key_disable_hw_accel(key);
510 work_done = true;
511 }
512 if (todoflags & KEY_FLAG_TODO_DELETE) {
513 __ieee80211_key_destroy(key);
514 work_done = true;
515 }
516
517 WARN_ON(!work_done);
518
519 spin_lock(&todo_lock);
520 }
521 spin_unlock(&todo_lock);
522 }
523
ieee80211_key_todo(void)524 void ieee80211_key_todo(void)
525 {
526 ieee80211_key_lock();
527 __ieee80211_key_todo();
528 ieee80211_key_unlock();
529 }
530
ieee80211_free_keys(struct ieee80211_sub_if_data * sdata)531 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
532 {
533 struct ieee80211_key *key, *tmp;
534 unsigned long flags;
535
536 ieee80211_key_lock();
537
538 ieee80211_debugfs_key_remove_default(sdata);
539
540 spin_lock_irqsave(&sdata->local->key_lock, flags);
541 list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
542 __ieee80211_key_free(key);
543 spin_unlock_irqrestore(&sdata->local->key_lock, flags);
544
545 __ieee80211_key_todo();
546
547 ieee80211_key_unlock();
548 }
549