xref: /openbmc/linux/net/mac80211/key.c (revision 22246614) 
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 == IEEE80211_IF_TYPE_AP ||
122 	     key->sdata->vif.type == IEEE80211_IF_TYPE_VLAN))
123 		addr = zero_addr;
124 
125 	if (key->sta)
126 		addr = key->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 	memcpy(key->conf.key, key_data, key_len);
285 	INIT_LIST_HEAD(&key->list);
286 	INIT_LIST_HEAD(&key->todo);
287 
288 	if (alg == ALG_CCMP) {
289 		/*
290 		 * Initialize AES key state here as an optimization so that
291 		 * it does not need to be initialized for every packet.
292 		 */
293 		key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
294 		if (!key->u.ccmp.tfm) {
295 			kfree(key);
296 			return NULL;
297 		}
298 	}
299 
300 	return key;
301 }
302 
303 void ieee80211_key_link(struct ieee80211_key *key,
304 			struct ieee80211_sub_if_data *sdata,
305 			struct sta_info *sta)
306 {
307 	struct ieee80211_key *old_key;
308 	unsigned long flags;
309 	int idx;
310 
311 	BUG_ON(!sdata);
312 	BUG_ON(!key);
313 
314 	idx = key->conf.keyidx;
315 	key->local = sdata->local;
316 	key->sdata = sdata;
317 	key->sta = sta;
318 
319 	if (sta) {
320 		/*
321 		 * some hardware cannot handle TKIP with QoS, so
322 		 * we indicate whether QoS could be in use.
323 		 */
324 		if (sta->flags & WLAN_STA_WME)
325 			key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
326 	} else {
327 		if (sdata->vif.type == IEEE80211_IF_TYPE_STA) {
328 			struct sta_info *ap;
329 
330 			/*
331 			 * We're getting a sta pointer in,
332 			 * so must be under RCU read lock.
333 			 */
334 
335 			/* same here, the AP could be using QoS */
336 			ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
337 			if (ap) {
338 				if (ap->flags & WLAN_STA_WME)
339 					key->conf.flags |=
340 						IEEE80211_KEY_FLAG_WMM_STA;
341 			}
342 		}
343 	}
344 
345 	spin_lock_irqsave(&sdata->local->key_lock, flags);
346 
347 	if (sta)
348 		old_key = sta->key;
349 	else
350 		old_key = sdata->keys[idx];
351 
352 	__ieee80211_key_replace(sdata, sta, old_key, key);
353 
354 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
355 
356 	/* free old key later */
357 	add_todo(old_key, KEY_FLAG_TODO_DELETE);
358 
359 	add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
360 	if (netif_running(sdata->dev))
361 		add_todo(key, KEY_FLAG_TODO_HWACCEL_ADD);
362 }
363 
364 static void __ieee80211_key_free(struct ieee80211_key *key)
365 {
366 	/*
367 	 * Replace key with nothingness if it was ever used.
368 	 */
369 	if (key->sdata)
370 		__ieee80211_key_replace(key->sdata, key->sta,
371 					key, NULL);
372 
373 	add_todo(key, KEY_FLAG_TODO_DELETE);
374 }
375 
376 void ieee80211_key_free(struct ieee80211_key *key)
377 {
378 	unsigned long flags;
379 
380 	if (!key)
381 		return;
382 
383 	spin_lock_irqsave(&key->sdata->local->key_lock, flags);
384 	__ieee80211_key_free(key);
385 	spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
386 }
387 
388 /*
389  * To be safe against concurrent manipulations of the list (which shouldn't
390  * actually happen) we need to hold the spinlock. But under the spinlock we
391  * can't actually do much, so we defer processing to the todo list. Then run
392  * the todo list to be sure the operation and possibly previously pending
393  * operations are completed.
394  */
395 static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
396 					u32 todo_flags)
397 {
398 	struct ieee80211_key *key;
399 	unsigned long flags;
400 
401 	might_sleep();
402 
403 	spin_lock_irqsave(&sdata->local->key_lock, flags);
404 	list_for_each_entry(key, &sdata->key_list, list)
405 		add_todo(key, todo_flags);
406 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
407 
408 	ieee80211_key_todo();
409 }
410 
411 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
412 {
413 	ASSERT_RTNL();
414 
415 	if (WARN_ON(!netif_running(sdata->dev)))
416 		return;
417 
418 	ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_ADD);
419 }
420 
421 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
422 {
423 	ASSERT_RTNL();
424 
425 	ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_REMOVE);
426 }
427 
428 static void __ieee80211_key_destroy(struct ieee80211_key *key)
429 {
430 	if (!key)
431 		return;
432 
433 	ieee80211_key_disable_hw_accel(key);
434 
435 	if (key->conf.alg == ALG_CCMP)
436 		ieee80211_aes_key_free(key->u.ccmp.tfm);
437 	ieee80211_debugfs_key_remove(key);
438 
439 	kfree(key);
440 }
441 
442 static void __ieee80211_key_todo(void)
443 {
444 	struct ieee80211_key *key;
445 	bool work_done;
446 	u32 todoflags;
447 
448 	/*
449 	 * NB: sta_info_destroy relies on this!
450 	 */
451 	synchronize_rcu();
452 
453 	spin_lock(&todo_lock);
454 	while (!list_empty(&todo_list)) {
455 		key = list_first_entry(&todo_list, struct ieee80211_key, todo);
456 		list_del_init(&key->todo);
457 		todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
458 					  KEY_FLAG_TODO_DEFKEY |
459 					  KEY_FLAG_TODO_HWACCEL_ADD |
460 					  KEY_FLAG_TODO_HWACCEL_REMOVE |
461 					  KEY_FLAG_TODO_DELETE);
462 		key->flags &= ~todoflags;
463 		spin_unlock(&todo_lock);
464 
465 		work_done = false;
466 
467 		if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
468 			ieee80211_debugfs_key_add(key);
469 			work_done = true;
470 		}
471 		if (todoflags & KEY_FLAG_TODO_DEFKEY) {
472 			ieee80211_debugfs_key_remove_default(key->sdata);
473 			ieee80211_debugfs_key_add_default(key->sdata);
474 			work_done = true;
475 		}
476 		if (todoflags & KEY_FLAG_TODO_HWACCEL_ADD) {
477 			ieee80211_key_enable_hw_accel(key);
478 			work_done = true;
479 		}
480 		if (todoflags & KEY_FLAG_TODO_HWACCEL_REMOVE) {
481 			ieee80211_key_disable_hw_accel(key);
482 			work_done = true;
483 		}
484 		if (todoflags & KEY_FLAG_TODO_DELETE) {
485 			__ieee80211_key_destroy(key);
486 			work_done = true;
487 		}
488 
489 		WARN_ON(!work_done);
490 
491 		spin_lock(&todo_lock);
492 	}
493 	spin_unlock(&todo_lock);
494 }
495 
496 void ieee80211_key_todo(void)
497 {
498 	ieee80211_key_lock();
499 	__ieee80211_key_todo();
500 	ieee80211_key_unlock();
501 }
502 
503 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
504 {
505 	struct ieee80211_key *key, *tmp;
506 	unsigned long flags;
507 
508 	ieee80211_key_lock();
509 
510 	ieee80211_debugfs_key_remove_default(sdata);
511 
512 	spin_lock_irqsave(&sdata->local->key_lock, flags);
513 	list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
514 		__ieee80211_key_free(key);
515 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
516 
517 	__ieee80211_key_todo();
518 
519 	ieee80211_key_unlock();
520 }
521