xref: /illumos-gate/usr/src/uts/common/io/net80211/net80211_crypto.c (revision 2d6eb4a5e0a47d30189497241345dc5466bb68ab)
1 /*
2  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
3  * Use is subject to license terms.
4  */
5 
6 /*
7  * Copyright (c) 2001 Atsushi Onoe
8  * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
9  * All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. The name of the author may not be used to endorse or promote products
20  *    derived from this software without specific prior written permission.
21  *
22  * Alternatively, this software may be distributed under the terms of the
23  * GNU General Public License ("GPL") version 2 as published by the Free
24  * Software Foundation.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36  */
37 
38 /*
39  * IEEE 802.11 generic crypto support
40  */
41 #include <sys/types.h>
42 #include <sys/note.h>
43 #include <sys/crypto/common.h>
44 #include <sys/crypto/api.h>
45 #include <sys/strsun.h>
46 #include "net80211_impl.h"
47 
48 extern const struct ieee80211_cipher wep;
49 extern const struct ieee80211_cipher tkip;
50 extern const struct ieee80211_cipher ccmp;
51 
52 /*
53  * Table of registered cipher modules.
54  */
55 static const char *cipher_modnames[] = {
56 	"wlan_wep",	/* IEEE80211_CIPHER_WEP */
57 	"wlan_tkip",	/* IEEE80211_CIPHER_TKIP */
58 	"wlan_aes_ocb",	/* IEEE80211_CIPHER_AES_OCB */
59 	"wlan_ccmp",	/* IEEE80211_CIPHER_AES_CCM */
60 	"wlan_ckip",	/* IEEE80211_CIPHER_CKIP */
61 };
62 
63 /*
64  * Default "null" key management routines.
65  */
66 /* ARGSUSED */
67 static int
nulldev_key_alloc(ieee80211com_t * ic,const struct ieee80211_key * k,ieee80211_keyix * keyix,ieee80211_keyix * rxkeyix)68 nulldev_key_alloc(ieee80211com_t *ic, const struct ieee80211_key *k,
69 	ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
70 {
71 	*keyix = 0;	/* use key index 0 for ucast key */
72 	*rxkeyix = IEEE80211_KEYIX_NONE;
73 	return (1);
74 }
75 
76 /* ARGSUSED */
77 static int
nulldev_key_delete(ieee80211com_t * ic,const struct ieee80211_key * k)78 nulldev_key_delete(ieee80211com_t *ic, const struct ieee80211_key *k)
79 {
80 	return (1);
81 }
82 
83 /* ARGSUSED */
84 static int
nulldev_key_set(ieee80211com_t * ic,const struct ieee80211_key * k,const uint8_t * mac)85 nulldev_key_set(ieee80211com_t *ic, const struct ieee80211_key *k,
86 	const uint8_t *mac)
87 {
88 	return (1);
89 }
90 
91 /* ARGSUSED */
92 static void
nulldev_key_update(ieee80211com_t * ic)93 nulldev_key_update(ieee80211com_t *ic)
94 {
95 	/* noop */
96 }
97 
98 /*
99  * Reset key state to an unused state.  The crypto
100  * key allocation mechanism insures other state (e.g.
101  * key data) is properly setup before a key is used.
102  */
103 void
ieee80211_crypto_resetkey(ieee80211com_t * ic,struct ieee80211_key * k,ieee80211_keyix ix)104 ieee80211_crypto_resetkey(ieee80211com_t *ic,
105     struct ieee80211_key *k, ieee80211_keyix ix)
106 {
107 	k->wk_cipher = &ieee80211_cipher_none;
108 	k->wk_private = k->wk_cipher->ic_attach(ic, k);
109 	k->wk_keyix = ix;
110 	k->wk_flags = IEEE80211_KEY_XMIT | IEEE80211_KEY_RECV;
111 }
112 
113 /*
114  * Establish a relationship between the specified key and cipher
115  * and, if necessary, allocate a hardware index from the driver.
116  * Note that when a fixed key index is required it must be specified
117  * and we blindly assign it w/o consulting the driver.
118  *
119  * This must be the first call applied to a key; all the other key
120  * routines assume wk_cipher is setup.
121  *
122  * Locking must be handled by the caller using:
123  *	ieee80211_key_update_begin(ic);
124  *	ieee80211_key_update_end(ic);
125  */
126 int
ieee80211_crypto_newkey(ieee80211com_t * ic,int cipher,int flags,struct ieee80211_key * key)127 ieee80211_crypto_newkey(ieee80211com_t *ic, int cipher, int flags,
128     struct ieee80211_key *key)
129 {
130 	const struct ieee80211_cipher *cip;
131 	ieee80211_keyix keyix, rxkeyix;
132 	void *keyctx;
133 	uint16_t oflags;
134 
135 	/*
136 	 * Validate cipher and set reference to cipher routines.
137 	 */
138 	if (cipher >= IEEE80211_CIPHER_MAX) {
139 		ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_newkey: "
140 		    "invalid cipher %u\n", cipher);
141 		return (0);
142 	}
143 	cip = ic->ic_ciphers[cipher];
144 	/* already load all the ciphers, cip can't be NULL */
145 	if (cip == NULL) {
146 		ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_newkey: "
147 		    "unable to load cipher %u, module %s\n",
148 		    cipher, cipher < IEEE80211_N(cipher_modnames) ?
149 		    cipher_modnames[cipher] : "<unknown>");
150 		return (0);
151 	}
152 
153 	oflags = key->wk_flags;
154 	flags &= IEEE80211_KEY_COMMON;
155 	/*
156 	 * If the hardware does not support the cipher then
157 	 * fallback to a host-based implementation.
158 	 */
159 	if ((ic->ic_caps & (1<<cipher)) == 0) {
160 		ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_newkey: "
161 		    "no h/w support for cipher %s, falling back to s/w\n",
162 		    cip->ic_name);
163 		flags |= IEEE80211_KEY_SWCRYPT;
164 	}
165 	/*
166 	 * Hardware TKIP with software MIC is an important
167 	 * combination; we handle it by flagging each key,
168 	 * the cipher modules honor it.
169 	 */
170 	if (cipher == IEEE80211_CIPHER_TKIP &&
171 	    (ic->ic_caps & IEEE80211_C_TKIPMIC) == 0) {
172 		ieee80211_dbg(IEEE80211_MSG_CRYPTO,
173 		    "no h/w support for TKIP MIC, falling back to s/w\n");
174 		flags |= IEEE80211_KEY_SWMIC;
175 	}
176 
177 	/*
178 	 * Bind cipher to key instance.  Note we do this
179 	 * after checking the device capabilities so the
180 	 * cipher module can optimize space usage based on
181 	 * whether or not it needs to do the cipher work.
182 	 */
183 	if (key->wk_cipher != cip || key->wk_flags != flags) {
184 again:
185 		/*
186 		 * Fillin the flags so cipher modules can see s/w
187 		 * crypto requirements and potentially allocate
188 		 * different state and/or attach different method
189 		 * pointers.
190 		 */
191 		key->wk_flags = (uint16_t)flags;
192 		keyctx = cip->ic_attach(ic, key);
193 		if (keyctx == NULL) {
194 			ieee80211_dbg(IEEE80211_MSG_CRYPTO, "crypto_setkey: "
195 			    "unable to attach cipher %s\n", cip->ic_name);
196 			key->wk_flags = oflags;	/* restore old flags */
197 			return (0);
198 		}
199 		CIPHER_DETACH(key);		/* Detach old cipher */
200 		key->wk_cipher = cip;
201 		key->wk_private = keyctx;
202 	}
203 	/*
204 	 * Commit to requested usage so driver can see the flags.
205 	 */
206 	key->wk_flags = (uint16_t)flags;
207 
208 	/*
209 	 * Ask the driver for a key index if we don't have one.
210 	 * Note that entries in the global key table always have
211 	 * an index; this means it's safe to call this routine
212 	 * for these entries just to setup the reference to the
213 	 * cipher template.  Note also that when using software
214 	 * crypto we also call the driver to give us a key index.
215 	 */
216 	if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
217 		if (!DEV_KEY_ALLOC(ic, key, &keyix, &rxkeyix)) {
218 			/*
219 			 * Driver has no room; fallback to doing crypto
220 			 * in the host.  We change the flags and start the
221 			 * procedure over.  If we get back here then there's
222 			 * no hope and we bail.  Note that this can leave
223 			 * the key in a inconsistent state if the caller
224 			 * continues to use it.
225 			 */
226 			if ((key->wk_flags & IEEE80211_KEY_SWCRYPT) == 0) {
227 				ieee80211_dbg(IEEE80211_MSG_CRYPTO,
228 				    "crypto_setkey: "
229 				    "no h/w resources for cipher %s, "
230 				    "falling back to s/w\n", cip->ic_name);
231 				oflags = key->wk_flags;
232 				flags |= IEEE80211_KEY_SWCRYPT;
233 				if (cipher == IEEE80211_CIPHER_TKIP)
234 					flags |= IEEE80211_KEY_SWMIC;
235 				goto again;
236 			}
237 			ieee80211_dbg(IEEE80211_MSG_CRYPTO, "crypto_setkey: "
238 			    "unable to setup cipher %s\n", cip->ic_name);
239 			return (0);
240 		}
241 		key->wk_keyix = keyix;
242 		key->wk_rxkeyix = rxkeyix;
243 	}
244 	return (1);
245 }
246 
247 /*
248  * Remove the key (no locking, for internal use).
249  */
250 static int
ieee80211_crypto_delkey_locked(ieee80211com_t * ic,struct ieee80211_key * key)251 ieee80211_crypto_delkey_locked(ieee80211com_t *ic, struct ieee80211_key *key)
252 {
253 	uint16_t keyix;
254 
255 	ASSERT(key->wk_cipher != NULL);
256 
257 	keyix = key->wk_keyix;
258 	if (keyix != IEEE80211_KEYIX_NONE) {
259 		/*
260 		 * Remove hardware entry.
261 		 */
262 		if (!DEV_KEY_DELETE(ic, key)) {
263 			ieee80211_dbg(IEEE80211_MSG_CRYPTO,
264 			    "ieee80211_crypto_delkey_locked: ",
265 			    "driverdeletes key %u failed\n", keyix);
266 		}
267 	}
268 	CIPHER_DETACH(key);
269 	bzero(key, sizeof (struct ieee80211_key));
270 	/* NB: cannot depend on key index to decide this */
271 	ieee80211_crypto_resetkey(ic, key, IEEE80211_KEYIX_NONE);
272 	return (1);
273 }
274 
275 /*
276  * Remove the specified key.
277  */
278 int
ieee80211_crypto_delkey(ieee80211com_t * ic,struct ieee80211_key * key)279 ieee80211_crypto_delkey(ieee80211com_t *ic, struct ieee80211_key *key)
280 {
281 	int status;
282 
283 	KEY_UPDATE_BEGIN(ic);
284 	status = ieee80211_crypto_delkey_locked(ic, key);
285 	KEY_UPDATE_END(ic);
286 	return (status);
287 }
288 
289 /*
290  * Clear the global key table.
291  */
292 static void
ieee80211_crypto_delglobalkeys(ieee80211com_t * ic)293 ieee80211_crypto_delglobalkeys(ieee80211com_t *ic)
294 {
295 	int i;
296 
297 	KEY_UPDATE_BEGIN(ic);
298 	for (i = 0; i < IEEE80211_WEP_NKID; i++)
299 		(void) ieee80211_crypto_delkey_locked(ic, &ic->ic_nw_keys[i]);
300 	KEY_UPDATE_END(ic);
301 }
302 
303 /*
304  * Set the contents of the specified key.
305  *
306  * Locking must be handled by the caller using:
307  *	ieee80211_key_update_begin(ic);
308  *	ieee80211_key_update_end(ic);
309  */
310 int
ieee80211_crypto_setkey(ieee80211com_t * ic,struct ieee80211_key * key,const uint8_t * macaddr)311 ieee80211_crypto_setkey(ieee80211com_t *ic, struct ieee80211_key *key,
312     const uint8_t *macaddr)
313 {
314 	const struct ieee80211_cipher *cip = key->wk_cipher;
315 
316 	ASSERT(cip != NULL);
317 
318 	ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_setkey: "
319 	    "%s keyix %u flags 0x%x mac %s len %u\n",
320 	    cip->ic_name, key->wk_keyix, key->wk_flags,
321 	    ieee80211_macaddr_sprintf(macaddr), key->wk_keylen);
322 
323 	/*
324 	 * Give cipher a chance to validate key contents.
325 	 * should happen before modifying state.
326 	 */
327 	if (cip->ic_setkey(key) == 0) {
328 		ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_setkey: "
329 		    "cipher %s rejected key index %u len %u flags 0x%x\n",
330 		    cip->ic_name, key->wk_keyix, key->wk_keylen,
331 		    key->wk_flags);
332 		return (0);
333 	}
334 	if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
335 		ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_setkey: "
336 		    "no key index; should not happen!\n");
337 		return (0);
338 	}
339 	return (DEV_KEY_SET(ic, key, macaddr));
340 }
341 
342 /*
343  * Return the transmit key to use in sending a frame.
344  */
345 struct ieee80211_key *
ieee80211_crypto_getkey(ieee80211com_t * ic)346 ieee80211_crypto_getkey(ieee80211com_t *ic)
347 {
348 	if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE ||
349 	    KEY_UNDEFINED(ic->ic_nw_keys[ic->ic_def_txkey]))
350 		return (NULL);
351 	return (&ic->ic_nw_keys[ic->ic_def_txkey]);
352 }
353 
354 uint8_t
ieee80211_crypto_getciphertype(ieee80211com_t * ic)355 ieee80211_crypto_getciphertype(ieee80211com_t *ic)
356 {
357 	struct ieee80211_key *key;
358 	uint32_t cipher;
359 	static const uint8_t ciphermap[] = {
360 		WIFI_SEC_WEP,	/* IEEE80211_CIPHER_WEP */
361 		WIFI_SEC_WPA,	/* IEEE80211_CIPHER_TKIP */
362 		(uint8_t)-1,	/* IEEE80211_CIPHER_AES_OCB */
363 		WIFI_SEC_WPA,	/* IEEE80211_CIPHER_AES_CCM */
364 		(uint8_t)-1,	/* IEEE80211_CIPHER_CKIP */
365 		WIFI_SEC_NONE,	/* IEEE80211_CIPHER_NONE */
366 	};
367 
368 	if ((ic->ic_flags & IEEE80211_F_PRIVACY) == 0)
369 		return (WIFI_SEC_NONE);
370 
371 	key = ieee80211_crypto_getkey(ic);
372 	if (key == NULL)
373 		return (WIFI_SEC_NONE);
374 
375 	cipher = key->wk_cipher->ic_cipher;
376 	ASSERT(cipher < IEEE80211_N(ciphermap));
377 	return (ciphermap[cipher]);
378 }
379 
380 /*
381  * Add privacy headers appropriate for the specified key.
382  */
383 struct ieee80211_key *
ieee80211_crypto_encap(ieee80211com_t * ic,mblk_t * mp)384 ieee80211_crypto_encap(ieee80211com_t *ic, mblk_t *mp)
385 {
386 	struct ieee80211_key *k;
387 	const struct ieee80211_cipher *cip;
388 	uint8_t keyix;
389 
390 	if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE) {
391 		ieee80211_dbg(IEEE80211_MSG_CRYPTO,
392 		    "ieee80211_crypto_encap: %s",
393 		    " No default xmit key for frame\n");
394 		return (NULL);
395 	}
396 	keyix = ic->ic_def_txkey;
397 	k = &ic->ic_nw_keys[ic->ic_def_txkey];
398 	cip = k->wk_cipher;
399 	return (cip->ic_encap(k, mp, keyix<<6) ? k : NULL);
400 }
401 
402 /*
403  * Validate and strip privacy headers (and trailer) for a
404  * received frame that has the WEP/Privacy bit set.
405  */
406 struct ieee80211_key *
ieee80211_crypto_decap(ieee80211com_t * ic,mblk_t * mp,int hdrlen)407 ieee80211_crypto_decap(ieee80211com_t *ic, mblk_t *mp, int hdrlen)
408 {
409 	struct ieee80211_key *k;
410 	const struct ieee80211_cipher *cip;
411 	uint8_t *ivp;
412 	uint8_t keyid;
413 
414 	/* NB: this minimum size data frame could be bigger */
415 	if (MBLKL(mp) < IEEE80211_WEP_MINLEN) {
416 		ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_decap:"
417 		    " WEP data frame too short, len %u\n",
418 		    MBLKL(mp));
419 		return (NULL);
420 	}
421 	/*
422 	 * Locate the key. If unicast and there is no unicast
423 	 * key then we fall back to the key id in the header.
424 	 * This assumes unicast keys are only configured when
425 	 * the key id in the header is meaningless (typically 0).
426 	 */
427 	ivp = mp->b_rptr + hdrlen;
428 	keyid = ivp[IEEE80211_WEP_IVLEN];
429 	k = &ic->ic_nw_keys[keyid >> 6];
430 
431 	/* check to avoid panic when wep is on but key is not set */
432 	if (k->wk_cipher == &ieee80211_cipher_none ||
433 	    k->wk_cipher == NULL)
434 		return (NULL);
435 
436 	cip = k->wk_cipher;
437 	return ((cip->ic_decap)(k, mp, hdrlen) ? k : NULL);
438 }
439 
440 /*
441  * Setup crypto support.
442  */
443 void
ieee80211_crypto_attach(ieee80211com_t * ic)444 ieee80211_crypto_attach(ieee80211com_t *ic)
445 {
446 	struct ieee80211_crypto_state *cs = &ic->ic_crypto;
447 	int i;
448 
449 	(void) crypto_mech2id(SUN_CKM_RC4); /* Load RC4 */
450 	(void) crypto_mech2id(SUN_CKM_AES_CBC); /* Load AES-CBC */
451 	(void) crypto_mech2id(SUN_CKM_AES_CCM); /* Load AES-CCM */
452 
453 	/* NB: we assume everything is pre-zero'd */
454 	cs->cs_def_txkey = IEEE80211_KEYIX_NONE;
455 	for (i = 0; i < IEEE80211_WEP_NKID; i++) {
456 		ieee80211_crypto_resetkey(ic, &cs->cs_nw_keys[i],
457 		    IEEE80211_KEYIX_NONE);
458 	}
459 
460 	/*
461 	 * Initialize the driver key support routines to noop entries.
462 	 * This is useful especially for the cipher test modules.
463 	 */
464 	cs->cs_key_alloc = nulldev_key_alloc;
465 	cs->cs_key_set = nulldev_key_set;
466 	cs->cs_key_delete = nulldev_key_delete;
467 	cs->cs_key_update_begin = nulldev_key_update;
468 	cs->cs_key_update_end = nulldev_key_update;
469 
470 	ieee80211_crypto_register(ic, &wep);
471 	ieee80211_crypto_register(ic, &tkip);
472 	ieee80211_crypto_register(ic, &ccmp);
473 }
474 
475 /*
476  * Teardown crypto support.
477  */
478 void
ieee80211_crypto_detach(ieee80211com_t * ic)479 ieee80211_crypto_detach(ieee80211com_t *ic)
480 {
481 	ieee80211_crypto_delglobalkeys(ic);
482 
483 	ieee80211_crypto_unregister(ic, &wep);
484 	ieee80211_crypto_unregister(ic, &tkip);
485 	ieee80211_crypto_unregister(ic, &ccmp);
486 }
487 
488 /*
489  * Register a crypto cipher module.
490  */
491 void
ieee80211_crypto_register(ieee80211com_t * ic,const struct ieee80211_cipher * cip)492 ieee80211_crypto_register(ieee80211com_t *ic,
493     const struct ieee80211_cipher *cip)
494 {
495 	if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
496 		ieee80211_err("ieee80211_crypto_register: "
497 		    "cipher %s has an invalid cipher index %u\n",
498 		    cip->ic_name, cip->ic_cipher);
499 		return;
500 	}
501 	if (ic->ic_ciphers[cip->ic_cipher] != NULL &&
502 	    ic->ic_ciphers[cip->ic_cipher] != cip) {
503 		ieee80211_err("ieee80211_crypto_register: "
504 		    "cipher %s registered with a different template\n",
505 		    cip->ic_name);
506 		return;
507 	}
508 	ic->ic_ciphers[cip->ic_cipher] = cip;
509 }
510 
511 /*
512  * Unregister a crypto cipher module.
513  */
514 void
ieee80211_crypto_unregister(ieee80211com_t * ic,const struct ieee80211_cipher * cip)515 ieee80211_crypto_unregister(ieee80211com_t *ic,
516     const struct ieee80211_cipher *cip)
517 {
518 	if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
519 		ieee80211_err("ieee80211_crypto_unregister: "
520 		    "cipher %s has an invalid cipher index %u\n",
521 		    cip->ic_name, cip->ic_cipher);
522 		return;
523 	}
524 	if (ic->ic_ciphers[cip->ic_cipher] != NULL &&
525 	    ic->ic_ciphers[cip->ic_cipher] != cip) {
526 		ieee80211_err("ieee80211_crypto_unregister: "
527 		    "cipher %s registered with a different template\n",
528 		    cip->ic_name);
529 		return;
530 	}
531 	/* NB: don't complain about not being registered */
532 	ic->ic_ciphers[cip->ic_cipher] = NULL;
533 }
534