xref: /linux/net/mac80211/key.c (revision a33f32244d8550da8b4a26e277ce07d5c6d158b5) 
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 <linux/slab.h>
18 #include <net/mac80211.h>
19 #include "ieee80211_i.h"
20 #include "driver-ops.h"
21 #include "debugfs_key.h"
22 #include "aes_ccm.h"
23 #include "aes_cmac.h"
24 
25 
26 /**
27  * DOC: Key handling basics
28  *
29  * Key handling in mac80211 is done based on per-interface (sub_if_data)
30  * keys and per-station keys. Since each station belongs to an interface,
31  * each station key also belongs to that interface.
32  *
33  * Hardware acceleration is done on a best-effort basis, for each key
34  * that is eligible the hardware is asked to enable that key but if
35  * it cannot do that they key is simply kept for software encryption.
36  * There is currently no way of knowing this except by looking into
37  * debugfs.
38  *
39  * All key operations are protected internally so you can call them at
40  * any time.
41  *
42  * Within mac80211, key references are, just as STA structure references,
43  * protected by RCU. Note, however, that some things are unprotected,
44  * namely the key->sta dereferences within the hardware acceleration
45  * functions. This means that sta_info_destroy() must flush the key todo
46  * list.
47  *
48  * All the direct key list manipulation functions must not sleep because
49  * they can operate on STA info structs that are protected by RCU.
50  */
51 
52 static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
53 
54 /* key mutex: used to synchronise todo runners */
55 static DEFINE_MUTEX(key_mutex);
56 static DEFINE_SPINLOCK(todo_lock);
57 static LIST_HEAD(todo_list);
58 
59 static void key_todo(struct work_struct *work)
60 {
61 	ieee80211_key_todo();
62 }
63 
64 static DECLARE_WORK(todo_work, key_todo);
65 
66 /**
67  * add_todo - add todo item for a key
68  *
69  * @key: key to add to do item for
70  * @flag: todo flag(s)
71  *
72  * Must be called with IRQs or softirqs disabled.
73  */
74 static void add_todo(struct ieee80211_key *key, u32 flag)
75 {
76 	if (!key)
77 		return;
78 
79 	spin_lock(&todo_lock);
80 	key->flags |= flag;
81 	/*
82 	 * Remove again if already on the list so that we move it to the end.
83 	 */
84 	if (!list_empty(&key->todo))
85 		list_del(&key->todo);
86 	list_add_tail(&key->todo, &todo_list);
87 	schedule_work(&todo_work);
88 	spin_unlock(&todo_lock);
89 }
90 
91 /**
92  * ieee80211_key_lock - lock the mac80211 key operation lock
93  *
94  * This locks the (global) mac80211 key operation lock, all
95  * key operations must be done under this lock.
96  */
97 static void ieee80211_key_lock(void)
98 {
99 	mutex_lock(&key_mutex);
100 }
101 
102 /**
103  * ieee80211_key_unlock - unlock the mac80211 key operation lock
104  */
105 static void ieee80211_key_unlock(void)
106 {
107 	mutex_unlock(&key_mutex);
108 }
109 
110 static void assert_key_lock(void)
111 {
112 	WARN_ON(!mutex_is_locked(&key_mutex));
113 }
114 
115 static struct ieee80211_sta *get_sta_for_key(struct ieee80211_key *key)
116 {
117 	if (key->sta)
118 		return &key->sta->sta;
119 
120 	return NULL;
121 }
122 
123 static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
124 {
125 	struct ieee80211_sub_if_data *sdata;
126 	struct ieee80211_sta *sta;
127 	int ret;
128 
129 	assert_key_lock();
130 	might_sleep();
131 
132 	if (!key->local->ops->set_key)
133 		return;
134 
135 	sta = get_sta_for_key(key);
136 
137 	sdata = key->sdata;
138 	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
139 		sdata = container_of(sdata->bss,
140 				     struct ieee80211_sub_if_data,
141 				     u.ap);
142 
143 	ret = drv_set_key(key->local, SET_KEY, sdata, sta, &key->conf);
144 
145 	if (!ret) {
146 		spin_lock_bh(&todo_lock);
147 		key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
148 		spin_unlock_bh(&todo_lock);
149 	}
150 
151 	if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
152 		printk(KERN_ERR "mac80211-%s: failed to set key "
153 		       "(%d, %pM) to hardware (%d)\n",
154 		       wiphy_name(key->local->hw.wiphy),
155 		       key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
156 }
157 
158 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
159 {
160 	struct ieee80211_sub_if_data *sdata;
161 	struct ieee80211_sta *sta;
162 	int ret;
163 
164 	assert_key_lock();
165 	might_sleep();
166 
167 	if (!key || !key->local->ops->set_key)
168 		return;
169 
170 	spin_lock_bh(&todo_lock);
171 	if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
172 		spin_unlock_bh(&todo_lock);
173 		return;
174 	}
175 	spin_unlock_bh(&todo_lock);
176 
177 	sta = get_sta_for_key(key);
178 	sdata = key->sdata;
179 
180 	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
181 		sdata = container_of(sdata->bss,
182 				     struct ieee80211_sub_if_data,
183 				     u.ap);
184 
185 	ret = drv_set_key(key->local, DISABLE_KEY, sdata,
186 			  sta, &key->conf);
187 
188 	if (ret)
189 		printk(KERN_ERR "mac80211-%s: failed to remove key "
190 		       "(%d, %pM) from hardware (%d)\n",
191 		       wiphy_name(key->local->hw.wiphy),
192 		       key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
193 
194 	spin_lock_bh(&todo_lock);
195 	key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
196 	spin_unlock_bh(&todo_lock);
197 }
198 
199 static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
200 					int idx)
201 {
202 	struct ieee80211_key *key = NULL;
203 
204 	if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
205 		key = sdata->keys[idx];
206 
207 	rcu_assign_pointer(sdata->default_key, key);
208 
209 	if (key)
210 		add_todo(key, KEY_FLAG_TODO_DEFKEY);
211 }
212 
213 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
214 {
215 	unsigned long flags;
216 
217 	spin_lock_irqsave(&sdata->local->key_lock, flags);
218 	__ieee80211_set_default_key(sdata, idx);
219 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
220 }
221 
222 static void
223 __ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata, int idx)
224 {
225 	struct ieee80211_key *key = NULL;
226 
227 	if (idx >= NUM_DEFAULT_KEYS &&
228 	    idx < NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
229 		key = sdata->keys[idx];
230 
231 	rcu_assign_pointer(sdata->default_mgmt_key, key);
232 
233 	if (key)
234 		add_todo(key, KEY_FLAG_TODO_DEFMGMTKEY);
235 }
236 
237 void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
238 				    int idx)
239 {
240 	unsigned long flags;
241 
242 	spin_lock_irqsave(&sdata->local->key_lock, flags);
243 	__ieee80211_set_default_mgmt_key(sdata, idx);
244 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
245 }
246 
247 
248 static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
249 				    struct sta_info *sta,
250 				    struct ieee80211_key *old,
251 				    struct ieee80211_key *new)
252 {
253 	int idx, defkey, defmgmtkey;
254 
255 	if (new)
256 		list_add(&new->list, &sdata->key_list);
257 
258 	if (sta) {
259 		rcu_assign_pointer(sta->key, new);
260 	} else {
261 		WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);
262 
263 		if (old)
264 			idx = old->conf.keyidx;
265 		else
266 			idx = new->conf.keyidx;
267 
268 		defkey = old && sdata->default_key == old;
269 		defmgmtkey = old && sdata->default_mgmt_key == old;
270 
271 		if (defkey && !new)
272 			__ieee80211_set_default_key(sdata, -1);
273 		if (defmgmtkey && !new)
274 			__ieee80211_set_default_mgmt_key(sdata, -1);
275 
276 		rcu_assign_pointer(sdata->keys[idx], new);
277 		if (defkey && new)
278 			__ieee80211_set_default_key(sdata, new->conf.keyidx);
279 		if (defmgmtkey && new)
280 			__ieee80211_set_default_mgmt_key(sdata,
281 							 new->conf.keyidx);
282 	}
283 
284 	if (old) {
285 		/*
286 		 * We'll use an empty list to indicate that the key
287 		 * has already been removed.
288 		 */
289 		list_del_init(&old->list);
290 	}
291 }
292 
293 struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
294 					  int idx,
295 					  size_t key_len,
296 					  const u8 *key_data,
297 					  size_t seq_len, const u8 *seq)
298 {
299 	struct ieee80211_key *key;
300 	int i, j;
301 
302 	BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS);
303 
304 	key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
305 	if (!key)
306 		return NULL;
307 
308 	/*
309 	 * Default to software encryption; we'll later upload the
310 	 * key to the hardware if possible.
311 	 */
312 	key->conf.flags = 0;
313 	key->flags = 0;
314 
315 	key->conf.alg = alg;
316 	key->conf.keyidx = idx;
317 	key->conf.keylen = key_len;
318 	switch (alg) {
319 	case ALG_WEP:
320 		key->conf.iv_len = WEP_IV_LEN;
321 		key->conf.icv_len = WEP_ICV_LEN;
322 		break;
323 	case ALG_TKIP:
324 		key->conf.iv_len = TKIP_IV_LEN;
325 		key->conf.icv_len = TKIP_ICV_LEN;
326 		if (seq) {
327 			for (i = 0; i < NUM_RX_DATA_QUEUES; i++) {
328 				key->u.tkip.rx[i].iv32 =
329 					get_unaligned_le32(&seq[2]);
330 				key->u.tkip.rx[i].iv16 =
331 					get_unaligned_le16(seq);
332 			}
333 		}
334 		break;
335 	case ALG_CCMP:
336 		key->conf.iv_len = CCMP_HDR_LEN;
337 		key->conf.icv_len = CCMP_MIC_LEN;
338 		if (seq) {
339 			for (i = 0; i < NUM_RX_DATA_QUEUES; i++)
340 				for (j = 0; j < CCMP_PN_LEN; j++)
341 					key->u.ccmp.rx_pn[i][j] =
342 						seq[CCMP_PN_LEN - j - 1];
343 		}
344 		break;
345 	case ALG_AES_CMAC:
346 		key->conf.iv_len = 0;
347 		key->conf.icv_len = sizeof(struct ieee80211_mmie);
348 		if (seq)
349 			for (j = 0; j < 6; j++)
350 				key->u.aes_cmac.rx_pn[j] = seq[6 - j - 1];
351 		break;
352 	}
353 	memcpy(key->conf.key, key_data, key_len);
354 	INIT_LIST_HEAD(&key->list);
355 	INIT_LIST_HEAD(&key->todo);
356 
357 	if (alg == ALG_CCMP) {
358 		/*
359 		 * Initialize AES key state here as an optimization so that
360 		 * it does not need to be initialized for every packet.
361 		 */
362 		key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
363 		if (!key->u.ccmp.tfm) {
364 			kfree(key);
365 			return NULL;
366 		}
367 	}
368 
369 	if (alg == ALG_AES_CMAC) {
370 		/*
371 		 * Initialize AES key state here as an optimization so that
372 		 * it does not need to be initialized for every packet.
373 		 */
374 		key->u.aes_cmac.tfm =
375 			ieee80211_aes_cmac_key_setup(key_data);
376 		if (!key->u.aes_cmac.tfm) {
377 			kfree(key);
378 			return NULL;
379 		}
380 	}
381 
382 	return key;
383 }
384 
385 void ieee80211_key_link(struct ieee80211_key *key,
386 			struct ieee80211_sub_if_data *sdata,
387 			struct sta_info *sta)
388 {
389 	struct ieee80211_key *old_key;
390 	unsigned long flags;
391 	int idx;
392 
393 	BUG_ON(!sdata);
394 	BUG_ON(!key);
395 
396 	idx = key->conf.keyidx;
397 	key->local = sdata->local;
398 	key->sdata = sdata;
399 	key->sta = sta;
400 
401 	if (sta) {
402 		/*
403 		 * some hardware cannot handle TKIP with QoS, so
404 		 * we indicate whether QoS could be in use.
405 		 */
406 		if (test_sta_flags(sta, WLAN_STA_WME))
407 			key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
408 
409 		/*
410 		 * This key is for a specific sta interface,
411 		 * inform the driver that it should try to store
412 		 * this key as pairwise key.
413 		 */
414 		key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
415 	} else {
416 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
417 			struct sta_info *ap;
418 
419 			/*
420 			 * We're getting a sta pointer in,
421 			 * so must be under RCU read lock.
422 			 */
423 
424 			/* same here, the AP could be using QoS */
425 			ap = sta_info_get(key->sdata, key->sdata->u.mgd.bssid);
426 			if (ap) {
427 				if (test_sta_flags(ap, WLAN_STA_WME))
428 					key->conf.flags |=
429 						IEEE80211_KEY_FLAG_WMM_STA;
430 			}
431 		}
432 	}
433 
434 	spin_lock_irqsave(&sdata->local->key_lock, flags);
435 
436 	if (sta)
437 		old_key = sta->key;
438 	else
439 		old_key = sdata->keys[idx];
440 
441 	__ieee80211_key_replace(sdata, sta, old_key, key);
442 
443 	/* free old key later */
444 	add_todo(old_key, KEY_FLAG_TODO_DELETE);
445 
446 	add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
447 	if (ieee80211_sdata_running(sdata))
448 		add_todo(key, KEY_FLAG_TODO_HWACCEL_ADD);
449 
450 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
451 }
452 
453 static void __ieee80211_key_free(struct ieee80211_key *key)
454 {
455 	/*
456 	 * Replace key with nothingness if it was ever used.
457 	 */
458 	if (key->sdata)
459 		__ieee80211_key_replace(key->sdata, key->sta,
460 					key, NULL);
461 
462 	add_todo(key, KEY_FLAG_TODO_DELETE);
463 }
464 
465 void ieee80211_key_free(struct ieee80211_key *key)
466 {
467 	unsigned long flags;
468 
469 	if (!key)
470 		return;
471 
472 	if (!key->sdata) {
473 		/* The key has not been linked yet, simply free it
474 		 * and don't Oops */
475 		if (key->conf.alg == ALG_CCMP)
476 			ieee80211_aes_key_free(key->u.ccmp.tfm);
477 		kfree(key);
478 		return;
479 	}
480 
481 	spin_lock_irqsave(&key->sdata->local->key_lock, flags);
482 	__ieee80211_key_free(key);
483 	spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
484 }
485 
486 /*
487  * To be safe against concurrent manipulations of the list (which shouldn't
488  * actually happen) we need to hold the spinlock. But under the spinlock we
489  * can't actually do much, so we defer processing to the todo list. Then run
490  * the todo list to be sure the operation and possibly previously pending
491  * operations are completed.
492  */
493 static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
494 					u32 todo_flags)
495 {
496 	struct ieee80211_key *key;
497 	unsigned long flags;
498 
499 	might_sleep();
500 
501 	spin_lock_irqsave(&sdata->local->key_lock, flags);
502 	list_for_each_entry(key, &sdata->key_list, list)
503 		add_todo(key, todo_flags);
504 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
505 
506 	ieee80211_key_todo();
507 }
508 
509 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
510 {
511 	ASSERT_RTNL();
512 
513 	if (WARN_ON(!ieee80211_sdata_running(sdata)))
514 		return;
515 
516 	ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_ADD);
517 }
518 
519 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
520 {
521 	ASSERT_RTNL();
522 
523 	ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_REMOVE);
524 }
525 
526 static void __ieee80211_key_destroy(struct ieee80211_key *key)
527 {
528 	if (!key)
529 		return;
530 
531 	ieee80211_key_disable_hw_accel(key);
532 
533 	if (key->conf.alg == ALG_CCMP)
534 		ieee80211_aes_key_free(key->u.ccmp.tfm);
535 	if (key->conf.alg == ALG_AES_CMAC)
536 		ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
537 	ieee80211_debugfs_key_remove(key);
538 
539 	kfree(key);
540 }
541 
542 static void __ieee80211_key_todo(void)
543 {
544 	struct ieee80211_key *key;
545 	bool work_done;
546 	u32 todoflags;
547 
548 	/*
549 	 * NB: sta_info_destroy relies on this!
550 	 */
551 	synchronize_rcu();
552 
553 	spin_lock_bh(&todo_lock);
554 	while (!list_empty(&todo_list)) {
555 		key = list_first_entry(&todo_list, struct ieee80211_key, todo);
556 		list_del_init(&key->todo);
557 		todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
558 					  KEY_FLAG_TODO_DEFKEY |
559 					  KEY_FLAG_TODO_DEFMGMTKEY |
560 					  KEY_FLAG_TODO_HWACCEL_ADD |
561 					  KEY_FLAG_TODO_HWACCEL_REMOVE |
562 					  KEY_FLAG_TODO_DELETE);
563 		key->flags &= ~todoflags;
564 		spin_unlock_bh(&todo_lock);
565 
566 		work_done = false;
567 
568 		if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
569 			ieee80211_debugfs_key_add(key);
570 			work_done = true;
571 		}
572 		if (todoflags & KEY_FLAG_TODO_DEFKEY) {
573 			ieee80211_debugfs_key_remove_default(key->sdata);
574 			ieee80211_debugfs_key_add_default(key->sdata);
575 			work_done = true;
576 		}
577 		if (todoflags & KEY_FLAG_TODO_DEFMGMTKEY) {
578 			ieee80211_debugfs_key_remove_mgmt_default(key->sdata);
579 			ieee80211_debugfs_key_add_mgmt_default(key->sdata);
580 			work_done = true;
581 		}
582 		if (todoflags & KEY_FLAG_TODO_HWACCEL_ADD) {
583 			ieee80211_key_enable_hw_accel(key);
584 			work_done = true;
585 		}
586 		if (todoflags & KEY_FLAG_TODO_HWACCEL_REMOVE) {
587 			ieee80211_key_disable_hw_accel(key);
588 			work_done = true;
589 		}
590 		if (todoflags & KEY_FLAG_TODO_DELETE) {
591 			__ieee80211_key_destroy(key);
592 			work_done = true;
593 		}
594 
595 		WARN_ON(!work_done);
596 
597 		spin_lock_bh(&todo_lock);
598 	}
599 	spin_unlock_bh(&todo_lock);
600 }
601 
602 void ieee80211_key_todo(void)
603 {
604 	ieee80211_key_lock();
605 	__ieee80211_key_todo();
606 	ieee80211_key_unlock();
607 }
608 
609 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
610 {
611 	struct ieee80211_key *key, *tmp;
612 	unsigned long flags;
613 
614 	ieee80211_key_lock();
615 
616 	ieee80211_debugfs_key_remove_default(sdata);
617 	ieee80211_debugfs_key_remove_mgmt_default(sdata);
618 
619 	spin_lock_irqsave(&sdata->local->key_lock, flags);
620 	list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
621 		__ieee80211_key_free(key);
622 	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
623 
624 	__ieee80211_key_todo();
625 
626 	ieee80211_key_unlock();
627 }
628