xref: /openbmc/linux/net/mac80211/key.c (revision 9ac8d3fb) 
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 	DECLARE_MAC_BUF(mac);
136 
137 	assert_key_lock();
138 	might_sleep();
139 
140 	if (!key->local->ops->set_key)
141 		return;
142 
143 	addr = get_mac_for_key(key);
144 
145 	ret = key->local->ops->set_key(local_to_hw(key->local), SET_KEY,
146 				       key->sdata->dev->dev_addr, addr,
147 				       &key->conf);
148 
149 	if (!ret) {
150 		spin_lock(&todo_lock);
151 		key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
152 		spin_unlock(&todo_lock);
153 	}
154 
155 	if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
156 		printk(KERN_ERR "mac80211-%s: failed to set key "
157 		       "(%d, %s) to hardware (%d)\n",
158 		       wiphy_name(key->local->hw.wiphy),
159 		       key->conf.keyidx, print_mac(mac, addr), ret);
160 }
161 
162 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
163 {
164 	const u8 *addr;
165 	int ret;
166 	DECLARE_MAC_BUF(mac);
167 
168 	assert_key_lock();
169 	might_sleep();
170 
171 	if (!key || !key->local->ops->set_key)
172 		return;
173 
174 	spin_lock(&todo_lock);
175 	if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
176 		spin_unlock(&todo_lock);
177 		return;
178 	}
179 	spin_unlock(&todo_lock);
180 
181 	addr = get_mac_for_key(key);
182 
183 	ret = key->local->ops->set_key(local_to_hw(key->local), DISABLE_KEY,
184 				       key->sdata->dev->dev_addr, addr,
185 				       &key->conf);
186 
187 	if (ret)
188 		printk(KERN_ERR "mac80211-%s: failed to remove key "
189 		       "(%d, %s) from hardware (%d)\n",
190 		       wiphy_name(key->local->hw.wiphy),
191 		       key->conf.keyidx, print_mac(mac, addr), ret);
192 
193 	spin_lock(&todo_lock);
194 	key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
195 	spin_unlock(&todo_lock);
196 }
197 
198 static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
199 					int idx)
200 {
201 	struct ieee80211_key *key = NULL;
202 
203 	if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
204 		key = sdata->keys[idx];
205 
206 	rcu_assign_pointer(sdata->default_key, key);
207 
208 	if (key)
209 		add_todo(key, KEY_FLAG_TODO_DEFKEY);
210 }
211 
212 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
213 {
214 	unsigned long flags;
215 
216 	spin_lock_irqsave(&sdata->local->key_lock, flags);
217 	__ieee80211_set_default_key(sdata, idx);
218 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
219 }
220 
221 
222 static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
223 				    struct sta_info *sta,
224 				    struct ieee80211_key *old,
225 				    struct ieee80211_key *new)
226 {
227 	int idx, defkey;
228 
229 	if (new)
230 		list_add(&new->list, &sdata->key_list);
231 
232 	if (sta) {
233 		rcu_assign_pointer(sta->key, new);
234 	} else {
235 		WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);
236 
237 		if (old)
238 			idx = old->conf.keyidx;
239 		else
240 			idx = new->conf.keyidx;
241 
242 		defkey = old && sdata->default_key == old;
243 
244 		if (defkey && !new)
245 			__ieee80211_set_default_key(sdata, -1);
246 
247 		rcu_assign_pointer(sdata->keys[idx], new);
248 		if (defkey && new)
249 			__ieee80211_set_default_key(sdata, new->conf.keyidx);
250 	}
251 
252 	if (old) {
253 		/*
254 		 * We'll use an empty list to indicate that the key
255 		 * has already been removed.
256 		 */
257 		list_del_init(&old->list);
258 	}
259 }
260 
261 struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
262 					  int idx,
263 					  size_t key_len,
264 					  const u8 *key_data)
265 {
266 	struct ieee80211_key *key;
267 
268 	BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS);
269 
270 	key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
271 	if (!key)
272 		return NULL;
273 
274 	/*
275 	 * Default to software encryption; we'll later upload the
276 	 * key to the hardware if possible.
277 	 */
278 	key->conf.flags = 0;
279 	key->flags = 0;
280 
281 	key->conf.alg = alg;
282 	key->conf.keyidx = idx;
283 	key->conf.keylen = key_len;
284 	switch (alg) {
285 	case ALG_WEP:
286 		key->conf.iv_len = WEP_IV_LEN;
287 		key->conf.icv_len = WEP_ICV_LEN;
288 		break;
289 	case ALG_TKIP:
290 		key->conf.iv_len = TKIP_IV_LEN;
291 		key->conf.icv_len = TKIP_ICV_LEN;
292 		break;
293 	case ALG_CCMP:
294 		key->conf.iv_len = CCMP_HDR_LEN;
295 		key->conf.icv_len = CCMP_MIC_LEN;
296 		break;
297 	}
298 	memcpy(key->conf.key, key_data, key_len);
299 	INIT_LIST_HEAD(&key->list);
300 	INIT_LIST_HEAD(&key->todo);
301 
302 	if (alg == ALG_CCMP) {
303 		/*
304 		 * Initialize AES key state here as an optimization so that
305 		 * it does not need to be initialized for every packet.
306 		 */
307 		key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
308 		if (!key->u.ccmp.tfm) {
309 			kfree(key);
310 			return NULL;
311 		}
312 	}
313 
314 	return key;
315 }
316 
317 void ieee80211_key_link(struct ieee80211_key *key,
318 			struct ieee80211_sub_if_data *sdata,
319 			struct sta_info *sta)
320 {
321 	struct ieee80211_key *old_key;
322 	unsigned long flags;
323 	int idx;
324 
325 	BUG_ON(!sdata);
326 	BUG_ON(!key);
327 
328 	idx = key->conf.keyidx;
329 	key->local = sdata->local;
330 	key->sdata = sdata;
331 	key->sta = sta;
332 
333 	if (sta) {
334 		/*
335 		 * some hardware cannot handle TKIP with QoS, so
336 		 * we indicate whether QoS could be in use.
337 		 */
338 		if (test_sta_flags(sta, WLAN_STA_WME))
339 			key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
340 
341 		/*
342 		 * This key is for a specific sta interface,
343 		 * inform the driver that it should try to store
344 		 * this key as pairwise key.
345 		 */
346 		key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
347 	} else {
348 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
349 			struct sta_info *ap;
350 
351 			/*
352 			 * We're getting a sta pointer in,
353 			 * so must be under RCU read lock.
354 			 */
355 
356 			/* same here, the AP could be using QoS */
357 			ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
358 			if (ap) {
359 				if (test_sta_flags(ap, WLAN_STA_WME))
360 					key->conf.flags |=
361 						IEEE80211_KEY_FLAG_WMM_STA;
362 			}
363 		}
364 	}
365 
366 	spin_lock_irqsave(&sdata->local->key_lock, flags);
367 
368 	if (sta)
369 		old_key = sta->key;
370 	else
371 		old_key = sdata->keys[idx];
372 
373 	__ieee80211_key_replace(sdata, sta, old_key, key);
374 
375 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
376 
377 	/* free old key later */
378 	add_todo(old_key, KEY_FLAG_TODO_DELETE);
379 
380 	add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
381 	if (netif_running(sdata->dev))
382 		add_todo(key, KEY_FLAG_TODO_HWACCEL_ADD);
383 }
384 
385 static void __ieee80211_key_free(struct ieee80211_key *key)
386 {
387 	/*
388 	 * Replace key with nothingness if it was ever used.
389 	 */
390 	if (key->sdata)
391 		__ieee80211_key_replace(key->sdata, key->sta,
392 					key, NULL);
393 
394 	add_todo(key, KEY_FLAG_TODO_DELETE);
395 }
396 
397 void ieee80211_key_free(struct ieee80211_key *key)
398 {
399 	unsigned long flags;
400 
401 	if (!key)
402 		return;
403 
404 	if (!key->sdata) {
405 		/* The key has not been linked yet, simply free it
406 		 * and don't Oops */
407 		if (key->conf.alg == ALG_CCMP)
408 			ieee80211_aes_key_free(key->u.ccmp.tfm);
409 		kfree(key);
410 		return;
411 	}
412 
413 	spin_lock_irqsave(&key->sdata->local->key_lock, flags);
414 	__ieee80211_key_free(key);
415 	spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
416 }
417 
418 /*
419  * To be safe against concurrent manipulations of the list (which shouldn't
420  * actually happen) we need to hold the spinlock. But under the spinlock we
421  * can't actually do much, so we defer processing to the todo list. Then run
422  * the todo list to be sure the operation and possibly previously pending
423  * operations are completed.
424  */
425 static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
426 					u32 todo_flags)
427 {
428 	struct ieee80211_key *key;
429 	unsigned long flags;
430 
431 	might_sleep();
432 
433 	spin_lock_irqsave(&sdata->local->key_lock, flags);
434 	list_for_each_entry(key, &sdata->key_list, list)
435 		add_todo(key, todo_flags);
436 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
437 
438 	ieee80211_key_todo();
439 }
440 
441 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
442 {
443 	ASSERT_RTNL();
444 
445 	if (WARN_ON(!netif_running(sdata->dev)))
446 		return;
447 
448 	ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_ADD);
449 }
450 
451 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
452 {
453 	ASSERT_RTNL();
454 
455 	ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_REMOVE);
456 }
457 
458 static void __ieee80211_key_destroy(struct ieee80211_key *key)
459 {
460 	if (!key)
461 		return;
462 
463 	ieee80211_key_disable_hw_accel(key);
464 
465 	if (key->conf.alg == ALG_CCMP)
466 		ieee80211_aes_key_free(key->u.ccmp.tfm);
467 	ieee80211_debugfs_key_remove(key);
468 
469 	kfree(key);
470 }
471 
472 static void __ieee80211_key_todo(void)
473 {
474 	struct ieee80211_key *key;
475 	bool work_done;
476 	u32 todoflags;
477 
478 	/*
479 	 * NB: sta_info_destroy relies on this!
480 	 */
481 	synchronize_rcu();
482 
483 	spin_lock(&todo_lock);
484 	while (!list_empty(&todo_list)) {
485 		key = list_first_entry(&todo_list, struct ieee80211_key, todo);
486 		list_del_init(&key->todo);
487 		todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
488 					  KEY_FLAG_TODO_DEFKEY |
489 					  KEY_FLAG_TODO_HWACCEL_ADD |
490 					  KEY_FLAG_TODO_HWACCEL_REMOVE |
491 					  KEY_FLAG_TODO_DELETE);
492 		key->flags &= ~todoflags;
493 		spin_unlock(&todo_lock);
494 
495 		work_done = false;
496 
497 		if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
498 			ieee80211_debugfs_key_add(key);
499 			work_done = true;
500 		}
501 		if (todoflags & KEY_FLAG_TODO_DEFKEY) {
502 			ieee80211_debugfs_key_remove_default(key->sdata);
503 			ieee80211_debugfs_key_add_default(key->sdata);
504 			work_done = true;
505 		}
506 		if (todoflags & KEY_FLAG_TODO_HWACCEL_ADD) {
507 			ieee80211_key_enable_hw_accel(key);
508 			work_done = true;
509 		}
510 		if (todoflags & KEY_FLAG_TODO_HWACCEL_REMOVE) {
511 			ieee80211_key_disable_hw_accel(key);
512 			work_done = true;
513 		}
514 		if (todoflags & KEY_FLAG_TODO_DELETE) {
515 			__ieee80211_key_destroy(key);
516 			work_done = true;
517 		}
518 
519 		WARN_ON(!work_done);
520 
521 		spin_lock(&todo_lock);
522 	}
523 	spin_unlock(&todo_lock);
524 }
525 
526 void ieee80211_key_todo(void)
527 {
528 	ieee80211_key_lock();
529 	__ieee80211_key_todo();
530 	ieee80211_key_unlock();
531 }
532 
533 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
534 {
535 	struct ieee80211_key *key, *tmp;
536 	unsigned long flags;
537 
538 	ieee80211_key_lock();
539 
540 	ieee80211_debugfs_key_remove_default(sdata);
541 
542 	spin_lock_irqsave(&sdata->local->key_lock, flags);
543 	list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
544 		__ieee80211_key_free(key);
545 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
546 
547 	__ieee80211_key_todo();
548 
549 	ieee80211_key_unlock();
550 }
551