xref: /freebsd/sys/net80211/ieee80211_crypto.c (revision 98e8df90b5cc5180c09e71998e5f3e05c76a4fe1)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2001 Atsushi Onoe
5  * Copyright (c) 2002-2008 Sam Leffler, Errno Consulting
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 /*
31  * IEEE 802.11 generic crypto support.
32  */
33 #include "opt_wlan.h"
34 
35 #include <sys/param.h>
36 #include <sys/kernel.h>
37 #include <sys/malloc.h>
38 #include <sys/mbuf.h>
39 
40 #include <sys/socket.h>
41 
42 #include <net/if.h>
43 #include <net/if_media.h>
44 #include <net/ethernet.h>		/* XXX ETHER_HDR_LEN */
45 
46 #include <net80211/ieee80211_var.h>
47 
48 MALLOC_DEFINE(M_80211_CRYPTO, "80211crypto", "802.11 crypto state");
49 
50 static	int _ieee80211_crypto_delkey(struct ieee80211vap *,
51 		struct ieee80211_key *);
52 
53 /*
54  * Table of registered cipher modules.
55  */
56 static	const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX];
57 
58 /*
59  * Default "null" key management routines.
60  */
61 static int
62 null_key_alloc(struct ieee80211vap *vap, struct ieee80211_key *k,
63 	ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
64 {
65 	if (!(&vap->iv_nw_keys[0] <= k &&
66 	     k < &vap->iv_nw_keys[IEEE80211_WEP_NKID])) {
67 		/*
68 		 * Not in the global key table, the driver should handle this
69 		 * by allocating a slot in the h/w key table/cache.  In
70 		 * lieu of that return key slot 0 for any unicast key
71 		 * request.  We disallow the request if this is a group key.
72 		 * This default policy does the right thing for legacy hardware
73 		 * with a 4 key table.  It also handles devices that pass
74 		 * packets through untouched when marked with the WEP bit
75 		 * and key index 0.
76 		 */
77 		if (k->wk_flags & IEEE80211_KEY_GROUP)
78 			return 0;
79 		*keyix = 0;	/* NB: use key index 0 for ucast key */
80 	} else {
81 		*keyix = ieee80211_crypto_get_key_wepidx(vap, k);
82 	}
83 	*rxkeyix = IEEE80211_KEYIX_NONE;	/* XXX maybe *keyix? */
84 	return 1;
85 }
86 static int
87 null_key_delete(struct ieee80211vap *vap, const struct ieee80211_key *k)
88 {
89 	return 1;
90 }
91 static 	int
92 null_key_set(struct ieee80211vap *vap, const struct ieee80211_key *k)
93 {
94 	return 1;
95 }
96 static void null_key_update(struct ieee80211vap *vap) {}
97 
98 /*
99  * Write-arounds for common operations.
100  */
101 static __inline void
102 cipher_detach(struct ieee80211_key *key)
103 {
104 	key->wk_cipher->ic_detach(key);
105 }
106 
107 static __inline void *
108 cipher_attach(struct ieee80211vap *vap, struct ieee80211_key *key)
109 {
110 	return key->wk_cipher->ic_attach(vap, key);
111 }
112 
113 /*
114  * Wrappers for driver key management methods.
115  */
116 static __inline int
117 dev_key_alloc(struct ieee80211vap *vap,
118 	struct ieee80211_key *key,
119 	ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
120 {
121 	return vap->iv_key_alloc(vap, key, keyix, rxkeyix);
122 }
123 
124 static __inline int
125 dev_key_delete(struct ieee80211vap *vap,
126 	const struct ieee80211_key *key)
127 {
128 	return vap->iv_key_delete(vap, key);
129 }
130 
131 static __inline int
132 dev_key_set(struct ieee80211vap *vap, const struct ieee80211_key *key)
133 {
134 	return vap->iv_key_set(vap, key);
135 }
136 
137 /*
138  * Setup crypto support for a device/shared instance.
139  */
140 void
141 ieee80211_crypto_attach(struct ieee80211com *ic)
142 {
143 	/* NB: we assume everything is pre-zero'd */
144 	ciphers[IEEE80211_CIPHER_NONE] = &ieee80211_cipher_none;
145 
146 	/*
147 	 * Default set of net80211 supported ciphers.
148 	 *
149 	 * These are the default set that all drivers are expected to
150 	 * support, either/or in hardware and software.
151 	 *
152 	 * Drivers can add their own support to this and the
153 	 * hardware cipher list (ic_cryptocaps.)
154 	 */
155 	ic->ic_sw_cryptocaps = IEEE80211_CRYPTO_WEP |
156 	    IEEE80211_CRYPTO_TKIP | IEEE80211_CRYPTO_AES_CCM;
157 }
158 
159 /*
160  * Teardown crypto support.
161  */
162 void
163 ieee80211_crypto_detach(struct ieee80211com *ic)
164 {
165 }
166 
167 /*
168  * Set the supported ciphers for software encryption.
169  */
170 void
171 ieee80211_crypto_set_supported_software_ciphers(struct ieee80211com *ic,
172     uint32_t cipher_set)
173 {
174 	ic->ic_sw_cryptocaps = cipher_set;
175 }
176 
177 /*
178  * Set the supported ciphers for hardware encryption.
179  */
180 void
181 ieee80211_crypto_set_supported_hardware_ciphers(struct ieee80211com *ic,
182     uint32_t cipher_set)
183 {
184 	ic->ic_cryptocaps = cipher_set;
185 }
186 
187 
188 /*
189  * Setup crypto support for a vap.
190  */
191 void
192 ieee80211_crypto_vattach(struct ieee80211vap *vap)
193 {
194 	int i;
195 
196 	/* NB: we assume everything is pre-zero'd */
197 	vap->iv_max_keyix = IEEE80211_WEP_NKID;
198 	vap->iv_def_txkey = IEEE80211_KEYIX_NONE;
199 	for (i = 0; i < IEEE80211_WEP_NKID; i++)
200 		ieee80211_crypto_resetkey(vap, &vap->iv_nw_keys[i],
201 			IEEE80211_KEYIX_NONE);
202 	/*
203 	 * Initialize the driver key support routines to noop entries.
204 	 * This is useful especially for the cipher test modules.
205 	 */
206 	vap->iv_key_alloc = null_key_alloc;
207 	vap->iv_key_set = null_key_set;
208 	vap->iv_key_delete = null_key_delete;
209 	vap->iv_key_update_begin = null_key_update;
210 	vap->iv_key_update_end = null_key_update;
211 }
212 
213 /*
214  * Teardown crypto support for a vap.
215  */
216 void
217 ieee80211_crypto_vdetach(struct ieee80211vap *vap)
218 {
219 	ieee80211_crypto_delglobalkeys(vap);
220 }
221 
222 /*
223  * Register a crypto cipher module.
224  */
225 void
226 ieee80211_crypto_register(const struct ieee80211_cipher *cip)
227 {
228 	if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
229 		printf("%s: cipher %s has an invalid cipher index %u\n",
230 			__func__, cip->ic_name, cip->ic_cipher);
231 		return;
232 	}
233 	if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
234 		printf("%s: cipher %s registered with a different template\n",
235 			__func__, cip->ic_name);
236 		return;
237 	}
238 	ciphers[cip->ic_cipher] = cip;
239 }
240 
241 /*
242  * Unregister a crypto cipher module.
243  */
244 void
245 ieee80211_crypto_unregister(const struct ieee80211_cipher *cip)
246 {
247 	if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
248 		printf("%s: cipher %s has an invalid cipher index %u\n",
249 			__func__, cip->ic_name, cip->ic_cipher);
250 		return;
251 	}
252 	if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
253 		printf("%s: cipher %s registered with a different template\n",
254 			__func__, cip->ic_name);
255 		return;
256 	}
257 	/* NB: don't complain about not being registered */
258 	/* XXX disallow if references */
259 	ciphers[cip->ic_cipher] = NULL;
260 }
261 
262 int
263 ieee80211_crypto_available(u_int cipher)
264 {
265 	return cipher < IEEE80211_CIPHER_MAX && ciphers[cipher] != NULL;
266 }
267 
268 /* XXX well-known names! */
269 static const char *cipher_modnames[IEEE80211_CIPHER_MAX] = {
270 	[IEEE80211_CIPHER_WEP]	   = "wlan_wep",
271 	[IEEE80211_CIPHER_TKIP]	   = "wlan_tkip",
272 	[IEEE80211_CIPHER_AES_OCB] = "wlan_aes_ocb",
273 	[IEEE80211_CIPHER_AES_CCM] = "wlan_ccmp",
274 	[IEEE80211_CIPHER_TKIPMIC] = "#4",	/* NB: reserved */
275 	[IEEE80211_CIPHER_CKIP]	   = "wlan_ckip",
276 	[IEEE80211_CIPHER_NONE]	   = "wlan_none",
277 	[IEEE80211_CIPHER_AES_CCM_256] = "wlan_ccmp",
278 	[IEEE80211_CIPHER_BIP_CMAC_128] = "wlan_bip_cmac",
279 	[IEEE80211_CIPHER_BIP_CMAC_256] = "wlan_bip_cmac",
280 	[IEEE80211_CIPHER_BIP_GMAC_128] = "wlan_bip_gmac",
281 	[IEEE80211_CIPHER_BIP_GMAC_256] = "wlan_bip_gmac",
282 	[IEEE80211_CIPHER_AES_GCM_128]  = "wlan_gcmp",
283 	[IEEE80211_CIPHER_AES_GCM_256]  = "wlan_gcmp",
284 };
285 
286 /* NB: there must be no overlap between user-supplied and device-owned flags */
287 CTASSERT((IEEE80211_KEY_COMMON & IEEE80211_KEY_DEVICE) == 0);
288 
289 /*
290  * Establish a relationship between the specified key and cipher
291  * and, if necessary, allocate a hardware index from the driver.
292  * Note that when a fixed key index is required it must be specified.
293  *
294  * This must be the first call applied to a key; all the other key
295  * routines assume wk_cipher is setup.
296  *
297  * Locking must be handled by the caller using:
298  *	ieee80211_key_update_begin(vap);
299  *	ieee80211_key_update_end(vap);
300  */
301 int
302 ieee80211_crypto_newkey(struct ieee80211vap *vap,
303 	int cipher, int flags, struct ieee80211_key *key)
304 {
305 	struct ieee80211com *ic = vap->iv_ic;
306 	const struct ieee80211_cipher *cip;
307 	ieee80211_keyix keyix, rxkeyix;
308 	void *keyctx;
309 	int oflags;
310 
311 	IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
312 	    "%s: cipher %u flags 0x%x keyix %u\n",
313 	    __func__, cipher, flags, key->wk_keyix);
314 
315 	/*
316 	 * Validate cipher and set reference to cipher routines.
317 	 */
318 	if (cipher >= IEEE80211_CIPHER_MAX) {
319 		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
320 		    "%s: invalid cipher %u\n", __func__, cipher);
321 		vap->iv_stats.is_crypto_badcipher++;
322 		return 0;
323 	}
324 	cip = ciphers[cipher];
325 	if (cip == NULL) {
326 		/*
327 		 * Auto-load cipher module if we have a well-known name
328 		 * for it.  It might be better to use string names rather
329 		 * than numbers and craft a module name based on the cipher
330 		 * name; e.g. wlan_cipher_<cipher-name>.
331 		 */
332 		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
333 		    "%s: unregistered cipher %u, load module %s\n",
334 		    __func__, cipher, cipher_modnames[cipher]);
335 		ieee80211_load_module(cipher_modnames[cipher]);
336 		/*
337 		 * If cipher module loaded it should immediately
338 		 * call ieee80211_crypto_register which will fill
339 		 * in the entry in the ciphers array.
340 		 */
341 		cip = ciphers[cipher];
342 		if (cip == NULL) {
343 			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
344 			    "%s: unable to load cipher %u, module %s\n",
345 			    __func__, cipher, cipher_modnames[cipher]);
346 			vap->iv_stats.is_crypto_nocipher++;
347 			return 0;
348 		}
349 	}
350 
351 	oflags = key->wk_flags;
352 	flags &= IEEE80211_KEY_COMMON;
353 	/* NB: preserve device attributes */
354 	flags |= (oflags & IEEE80211_KEY_DEVICE);
355 	/*
356 	 * If the hardware does not support the cipher then
357 	 * fallback to a host-based implementation.
358 	 */
359 	if ((ic->ic_cryptocaps & (1<<cipher)) == 0) {
360 		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
361 		    "%s: no h/w support for cipher %s, falling back to s/w\n",
362 		    __func__, cip->ic_name);
363 		flags |= IEEE80211_KEY_SWCRYPT;
364 	}
365 	/*
366 	 * Hardware TKIP with software MIC is an important
367 	 * combination; we handle it by flagging each key,
368 	 * the cipher modules honor it.
369 	 */
370 	if (cipher == IEEE80211_CIPHER_TKIP &&
371 	    (ic->ic_cryptocaps & IEEE80211_CRYPTO_TKIPMIC) == 0) {
372 		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
373 		    "%s: no h/w support for TKIP MIC, falling back to s/w\n",
374 		    __func__);
375 		flags |= IEEE80211_KEY_SWMIC;
376 	}
377 
378 	/*
379 	 * Bind cipher to key instance.  Note we do this
380 	 * after checking the device capabilities so the
381 	 * cipher module can optimize space usage based on
382 	 * whether or not it needs to do the cipher work.
383 	 */
384 	if (key->wk_cipher != cip || key->wk_flags != flags) {
385 		/*
386 		 * Fillin the flags so cipher modules can see s/w
387 		 * crypto requirements and potentially allocate
388 		 * different state and/or attach different method
389 		 * pointers.
390 		 */
391 		key->wk_flags = flags;
392 		keyctx = cip->ic_attach(vap, key);
393 		if (keyctx == NULL) {
394 			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
395 				"%s: unable to attach cipher %s\n",
396 				__func__, cip->ic_name);
397 			key->wk_flags = oflags;	/* restore old flags */
398 			vap->iv_stats.is_crypto_attachfail++;
399 			return 0;
400 		}
401 		cipher_detach(key);
402 		key->wk_cipher = cip;		/* XXX refcnt? */
403 		key->wk_private = keyctx;
404 	}
405 
406 	/*
407 	 * Ask the driver for a key index if we don't have one.
408 	 * Note that entries in the global key table always have
409 	 * an index; this means it's safe to call this routine
410 	 * for these entries just to setup the reference to the
411 	 * cipher template.  Note also that when using software
412 	 * crypto we also call the driver to give us a key index.
413 	 */
414 	if ((key->wk_flags & IEEE80211_KEY_DEVKEY) == 0) {
415 		if (!dev_key_alloc(vap, key, &keyix, &rxkeyix)) {
416 			/*
417 			 * Unable to setup driver state.
418 			 */
419 			vap->iv_stats.is_crypto_keyfail++;
420 			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
421 			    "%s: unable to setup cipher %s\n",
422 			    __func__, cip->ic_name);
423 			return 0;
424 		}
425 		if (key->wk_flags != flags) {
426 			/*
427 			 * Driver overrode flags we setup; typically because
428 			 * resources were unavailable to handle _this_ key.
429 			 * Re-attach the cipher context to allow cipher
430 			 * modules to handle differing requirements.
431 			 */
432 			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
433 			    "%s: driver override for cipher %s, flags "
434 			    "0x%x -> 0x%x\n", __func__, cip->ic_name,
435 			    oflags, key->wk_flags);
436 			keyctx = cip->ic_attach(vap, key);
437 			if (keyctx == NULL) {
438 				IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
439 				    "%s: unable to attach cipher %s with "
440 				    "flags 0x%x\n", __func__, cip->ic_name,
441 				    key->wk_flags);
442 				key->wk_flags = oflags;	/* restore old flags */
443 				vap->iv_stats.is_crypto_attachfail++;
444 				return 0;
445 			}
446 			cipher_detach(key);
447 			key->wk_cipher = cip;		/* XXX refcnt? */
448 			key->wk_private = keyctx;
449 		}
450 		key->wk_keyix = keyix;
451 		key->wk_rxkeyix = rxkeyix;
452 		key->wk_flags |= IEEE80211_KEY_DEVKEY;
453 	}
454 	return 1;
455 }
456 
457 /*
458  * Remove the key (no locking, for internal use).
459  */
460 static int
461 _ieee80211_crypto_delkey(struct ieee80211vap *vap, struct ieee80211_key *key)
462 {
463 	KASSERT(key->wk_cipher != NULL, ("No cipher!"));
464 
465 	IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
466 	    "%s: %s keyix %u flags 0x%x rsc %ju tsc %ju len %u\n",
467 	    __func__, key->wk_cipher->ic_name,
468 	    key->wk_keyix, key->wk_flags,
469 	    key->wk_keyrsc[IEEE80211_NONQOS_TID], key->wk_keytsc,
470 	    key->wk_keylen);
471 
472 	if (key->wk_flags & IEEE80211_KEY_DEVKEY) {
473 		/*
474 		 * Remove hardware entry.
475 		 */
476 		/* XXX key cache */
477 		if (!dev_key_delete(vap, key)) {
478 			IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
479 			    "%s: driver did not delete key index %u\n",
480 			    __func__, key->wk_keyix);
481 			vap->iv_stats.is_crypto_delkey++;
482 			/* XXX recovery? */
483 		}
484 	}
485 	cipher_detach(key);
486 	memset(key, 0, sizeof(*key));
487 	ieee80211_crypto_resetkey(vap, key, IEEE80211_KEYIX_NONE);
488 	return 1;
489 }
490 
491 /*
492  * Remove the specified key.
493  */
494 int
495 ieee80211_crypto_delkey(struct ieee80211vap *vap, struct ieee80211_key *key)
496 {
497 	int status;
498 
499 	ieee80211_key_update_begin(vap);
500 	status = _ieee80211_crypto_delkey(vap, key);
501 	ieee80211_key_update_end(vap);
502 	return status;
503 }
504 
505 /*
506  * Clear the global key table.
507  */
508 void
509 ieee80211_crypto_delglobalkeys(struct ieee80211vap *vap)
510 {
511 	int i;
512 
513 	ieee80211_key_update_begin(vap);
514 	for (i = 0; i < IEEE80211_WEP_NKID; i++)
515 		(void) _ieee80211_crypto_delkey(vap, &vap->iv_nw_keys[i]);
516 	ieee80211_key_update_end(vap);
517 }
518 
519 /*
520  * Set the contents of the specified key.
521  *
522  * Locking must be handled by the caller using:
523  *	ieee80211_key_update_begin(vap);
524  *	ieee80211_key_update_end(vap);
525  */
526 int
527 ieee80211_crypto_setkey(struct ieee80211vap *vap, struct ieee80211_key *key)
528 {
529 	const struct ieee80211_cipher *cip = key->wk_cipher;
530 
531 	KASSERT(cip != NULL, ("No cipher!"));
532 
533 	IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
534 	    "%s: %s keyix %u flags 0x%x mac %s rsc %ju tsc %ju len %u\n",
535 	    __func__, cip->ic_name, key->wk_keyix,
536 	    key->wk_flags, ether_sprintf(key->wk_macaddr),
537 	    key->wk_keyrsc[IEEE80211_NONQOS_TID], key->wk_keytsc,
538 	    key->wk_keylen);
539 
540 	if ((key->wk_flags & IEEE80211_KEY_DEVKEY)  == 0) {
541 		/* XXX nothing allocated, should not happen */
542 		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
543 		    "%s: no device key setup done; should not happen!\n",
544 		    __func__);
545 		vap->iv_stats.is_crypto_setkey_nokey++;
546 		return 0;
547 	}
548 	/*
549 	 * Give cipher a chance to validate key contents.
550 	 * XXX should happen before modifying state.
551 	 */
552 	if (!cip->ic_setkey(key)) {
553 		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
554 		    "%s: cipher %s rejected key index %u len %u flags 0x%x\n",
555 		    __func__, cip->ic_name, key->wk_keyix,
556 		    key->wk_keylen, key->wk_flags);
557 		vap->iv_stats.is_crypto_setkey_cipher++;
558 		return 0;
559 	}
560 	return dev_key_set(vap, key);
561 }
562 
563 /*
564  * Return index if the key is a WEP key (0..3); -1 otherwise.
565  *
566  * This is different to "get_keyid" which defaults to returning
567  * 0 for unicast keys; it assumes that it won't be used for WEP.
568  */
569 int
570 ieee80211_crypto_get_key_wepidx(const struct ieee80211vap *vap,
571     const struct ieee80211_key *k)
572 {
573 
574 	if (k >= &vap->iv_nw_keys[0] &&
575 	    k <  &vap->iv_nw_keys[IEEE80211_WEP_NKID])
576 		return (k - vap->iv_nw_keys);
577 	return (-1);
578 }
579 
580 /*
581  * Note: only supports a single unicast key (0).
582  */
583 uint8_t
584 ieee80211_crypto_get_keyid(struct ieee80211vap *vap, struct ieee80211_key *k)
585 {
586 	if (k >= &vap->iv_nw_keys[0] &&
587 	    k <  &vap->iv_nw_keys[IEEE80211_WEP_NKID])
588 		return (k - vap->iv_nw_keys);
589 	else
590 		return (0);
591 }
592 
593 struct ieee80211_key *
594 ieee80211_crypto_get_txkey(struct ieee80211_node *ni, struct mbuf *m)
595 {
596 	struct ieee80211vap *vap = ni->ni_vap;
597 	struct ieee80211_frame *wh;
598 
599 	/*
600 	 * Multicast traffic always uses the multicast key.
601 	 *
602 	 * Historically we would fall back to the default
603 	 * transmit key if there was no unicast key.  This
604 	 * behaviour was documented up to IEEE Std 802.11-2016,
605 	 * 12.9.2.2 Per-MSDU/Per-A-MSDU Tx pseudocode, in the
606 	 * 'else' case but is no longer in later versions of
607 	 * the standard.  Additionally falling back to the
608 	 * group key for unicast was a security risk.
609 	 */
610 	wh = mtod(m, struct ieee80211_frame *);
611 	if (IEEE80211_IS_MULTICAST(wh->i_addr1)) {
612 		if (vap->iv_def_txkey == IEEE80211_KEYIX_NONE) {
613 			IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
614 			    wh->i_addr1,
615 			    "no default transmit key (%s) deftxkey %u",
616 			    __func__, vap->iv_def_txkey);
617 			vap->iv_stats.is_tx_nodefkey++;
618 			return NULL;
619 		}
620 		return &vap->iv_nw_keys[vap->iv_def_txkey];
621 	}
622 
623 	if (IEEE80211_KEY_UNDEFINED(&ni->ni_ucastkey))
624 		return NULL;
625 	return &ni->ni_ucastkey;
626 }
627 
628 /*
629  * Add privacy headers appropriate for the specified key.
630  */
631 struct ieee80211_key *
632 ieee80211_crypto_encap(struct ieee80211_node *ni, struct mbuf *m)
633 {
634 	struct ieee80211_key *k;
635 	const struct ieee80211_cipher *cip;
636 
637 	if ((k = ieee80211_crypto_get_txkey(ni, m)) != NULL) {
638 		cip = k->wk_cipher;
639 		return (cip->ic_encap(k, m) ? k : NULL);
640 	}
641 
642 	return NULL;
643 }
644 
645 /*
646  * Validate and strip privacy headers (and trailer) for a
647  * received frame that has the WEP/Privacy bit set.
648  */
649 int
650 ieee80211_crypto_decap(struct ieee80211_node *ni, struct mbuf *m, int hdrlen,
651     struct ieee80211_key **key)
652 {
653 #define	IEEE80211_WEP_HDRLEN	(IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN)
654 #define	IEEE80211_WEP_MINLEN \
655 	(sizeof(struct ieee80211_frame) + \
656 	IEEE80211_WEP_HDRLEN + IEEE80211_WEP_CRCLEN)
657 	struct ieee80211vap *vap = ni->ni_vap;
658 	struct ieee80211_key *k;
659 	struct ieee80211_frame *wh;
660 	const struct ieee80211_rx_stats *rxs;
661 	const struct ieee80211_cipher *cip;
662 	uint8_t keyid;
663 
664 	/*
665 	 * Check for hardware decryption and IV stripping.
666 	 * If the IV is stripped then we definitely can't find a key.
667 	 * Set the key to NULL but return true; upper layers
668 	 * will need to handle a NULL key for a successful
669 	 * decrypt.
670 	 */
671 	rxs = ieee80211_get_rx_params_ptr(m);
672 	if ((rxs != NULL) && (rxs->c_pktflags & IEEE80211_RX_F_DECRYPTED)) {
673 		if (rxs->c_pktflags & IEEE80211_RX_F_IV_STRIP) {
674 			/*
675 			 * Hardware decrypted, IV stripped.
676 			 * We can't find a key with a stripped IV.
677 			 * Return successful.
678 			 */
679 			*key = NULL;
680 			return (1);
681 		}
682 	}
683 
684 	/* NB: this minimum size data frame could be bigger */
685 	if (m->m_pkthdr.len < IEEE80211_WEP_MINLEN) {
686 		IEEE80211_DPRINTF(vap, IEEE80211_MSG_ANY,
687 			"%s: WEP data frame too short, len %u\n",
688 			__func__, m->m_pkthdr.len);
689 		vap->iv_stats.is_rx_tooshort++;	/* XXX need unique stat? */
690 		*key = NULL;
691 		return (0);
692 	}
693 
694 	/*
695 	 * Locate the key. If unicast and there is no unicast
696 	 * key then we fall back to the key id in the header.
697 	 * This assumes unicast keys are only configured when
698 	 * the key id in the header is meaningless (typically 0).
699 	 */
700 	wh = mtod(m, struct ieee80211_frame *);
701 	m_copydata(m, hdrlen + IEEE80211_WEP_IVLEN, sizeof(keyid), &keyid);
702 	if (IEEE80211_IS_MULTICAST(wh->i_addr1) ||
703 	    IEEE80211_KEY_UNDEFINED(&ni->ni_ucastkey))
704 		k = &vap->iv_nw_keys[keyid >> 6];
705 	else
706 		k = &ni->ni_ucastkey;
707 
708 	/*
709 	 * Insure crypto header is contiguous and long enough for all
710 	 * decap work.
711 	 */
712 	cip = k->wk_cipher;
713 	if (m->m_len < hdrlen + cip->ic_header) {
714 		IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
715 		    "frame is too short (%d < %u) for crypto decap",
716 		    cip->ic_name, m->m_len, hdrlen + cip->ic_header);
717 		vap->iv_stats.is_rx_tooshort++;
718 		*key = NULL;
719 		return (0);
720 	}
721 
722 	/*
723 	 * Attempt decryption.
724 	 *
725 	 * If we fail then don't return the key - return NULL
726 	 * and an error.
727 	 */
728 	if (cip->ic_decap(k, m, hdrlen)) {
729 		/* success */
730 		*key = k;
731 		return (1);
732 	}
733 
734 	/* Failure */
735 	*key = NULL;
736 	return (0);
737 #undef IEEE80211_WEP_MINLEN
738 #undef IEEE80211_WEP_HDRLEN
739 }
740 
741 /*
742  * Check and remove any MIC.
743  */
744 int
745 ieee80211_crypto_demic(struct ieee80211vap *vap, struct ieee80211_key *k,
746     struct mbuf *m, int force)
747 {
748 	const struct ieee80211_cipher *cip;
749 	const struct ieee80211_rx_stats *rxs;
750 	struct ieee80211_frame *wh;
751 
752 	rxs = ieee80211_get_rx_params_ptr(m);
753 	wh = mtod(m, struct ieee80211_frame *);
754 
755 	/*
756 	 * Handle demic / mic errors from hardware-decrypted offload devices.
757 	 */
758 	if ((rxs != NULL) && (rxs->c_pktflags & IEEE80211_RX_F_DECRYPTED)) {
759 		if (rxs->c_pktflags & IEEE80211_RX_F_FAIL_MIC) {
760 			/*
761 			 * Hardware has said MIC failed.  We don't care about
762 			 * whether it was stripped or not.
763 			 *
764 			 * Eventually - teach the demic methods in crypto
765 			 * modules to handle a NULL key and not to dereference
766 			 * it.
767 			 */
768 			ieee80211_notify_michael_failure(vap, wh, -1);
769 			return (0);
770 		}
771 
772 		if (rxs->c_pktflags & IEEE80211_RX_F_MMIC_STRIP) {
773 			/*
774 			 * Hardware has decrypted and not indicated a
775 			 * MIC failure and has stripped the MIC.
776 			 * We may not have a key, so for now just
777 			 * return OK.
778 			 */
779 			return (1);
780 		}
781 	}
782 
783 	/*
784 	 * If we don't have a key at this point then we don't
785 	 * have to demic anything.
786 	 */
787 	if (k == NULL)
788 		return (1);
789 
790 	cip = k->wk_cipher;
791 	return (cip->ic_miclen > 0 ? cip->ic_demic(k, m, force) : 1);
792 }
793 
794 static void
795 load_ucastkey(void *arg, struct ieee80211_node *ni)
796 {
797 	struct ieee80211vap *vap = ni->ni_vap;
798 	struct ieee80211_key *k;
799 
800 	if (vap->iv_state != IEEE80211_S_RUN)
801 		return;
802 	k = &ni->ni_ucastkey;
803 	if (k->wk_flags & IEEE80211_KEY_DEVKEY)
804 		dev_key_set(vap, k);
805 }
806 
807 /*
808  * Re-load all keys known to the 802.11 layer that may
809  * have hardware state backing them.  This is used by
810  * drivers on resume to push keys down into the device.
811  */
812 void
813 ieee80211_crypto_reload_keys(struct ieee80211com *ic)
814 {
815 	struct ieee80211vap *vap;
816 	int i;
817 
818 	/*
819 	 * Keys in the global key table of each vap.
820 	 */
821 	/* NB: used only during resume so don't lock for now */
822 	TAILQ_FOREACH(vap, &ic->ic_vaps, iv_next) {
823 		if (vap->iv_state != IEEE80211_S_RUN)
824 			continue;
825 		for (i = 0; i < IEEE80211_WEP_NKID; i++) {
826 			const struct ieee80211_key *k = &vap->iv_nw_keys[i];
827 			if (k->wk_flags & IEEE80211_KEY_DEVKEY)
828 				dev_key_set(vap, k);
829 		}
830 	}
831 	/*
832 	 * Unicast keys.
833 	 */
834 	ieee80211_iterate_nodes(&ic->ic_sta, load_ucastkey, NULL);
835 }
836 
837 /*
838  * Set the default key index for WEP, or KEYIX_NONE for no default TX key.
839  *
840  * This should be done as part of a key update block (iv_key_update_begin /
841  * iv_key_update_end.)
842  */
843 void
844 ieee80211_crypto_set_deftxkey(struct ieee80211vap *vap, ieee80211_keyix kid)
845 {
846 
847 	/* XXX TODO: assert we're in a key update block */
848 
849 	vap->iv_update_deftxkey(vap, kid);
850 }
851