xref: /openbmc/linux/net/mac80211/key.c (revision 8db70d3d) 
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.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 
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 }
606