xref: /linux/net/mac80211/key.c (revision b233b28eac0cc37d07c2d007ea08c86c778c5af4) 
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 
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 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 
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 
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 
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 
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 
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 
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 
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 
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  */
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 
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 
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 
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 
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 
524 void ieee80211_key_todo(void)
525 {
526 	ieee80211_key_lock();
527 	__ieee80211_key_todo();
528 	ieee80211_key_unlock();
529 }
530 
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