1 /*-
2 * Copyright (c) 2001 Atsushi Onoe
3 * Copyright (c) 2002-2007 Sam Leffler, Errno Consulting
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29
30 /*
31 * IEEE 802.11 generic crypto support.
32 */
33 #include <sys/param.h>
34 #include <sys/mbuf.h>
35
36 #include <sys/socket.h>
37
38 #include <net/if.h>
39 #include <net/if_media.h>
40 #include <net/ethernet.h> /* XXX ETHER_HDR_LEN */
41
42 #include <net80211/ieee80211_var.h>
43
44 /*
45 * Table of registered cipher modules.
46 */
47 static const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX];
48
49 static int _ieee80211_crypto_delkey(struct ieee80211com *,
50 struct ieee80211_key *);
51
52 /*
53 * Default "null" key management routines.
54 */
55 static int
56 null_key_alloc(struct ieee80211com *ic, const struct ieee80211_key *k,
57 ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
58 {
59 if (!(&ic->ic_nw_keys[0] <= k &&
60 k < &ic->ic_nw_keys[IEEE80211_WEP_NKID])) {
61 /*
62 * Not in the global key table, the driver should handle this
63 * by allocating a slot in the h/w key table/cache. In
64 * lieu of that return key slot 0 for any unicast key
65 * request. We disallow the request if this is a group key.
66 * This default policy does the right thing for legacy hardware
67 * with a 4 key table. It also handles devices that pass
68 * packets through untouched when marked with the WEP bit
69 * and key index 0.
70 */
71 if (k->wk_flags & IEEE80211_KEY_GROUP)
72 return 0;
73 *keyix = 0; /* NB: use key index 0 for ucast key */
74 } else {
75 *keyix = k - ic->ic_nw_keys;
76 }
77 *rxkeyix = IEEE80211_KEYIX_NONE; /* XXX maybe *keyix? */
78 return 1;
79 }
80 static int
81 null_key_delete(struct ieee80211com *ic, const struct ieee80211_key *k)
82 {
83 return 1;
84 }
85 static int
86 null_key_set(struct ieee80211com *ic, const struct ieee80211_key *k,
87 const uint8_t mac[IEEE80211_ADDR_LEN])
88 {
89 return 1;
90 }
91 static void null_key_update(struct ieee80211com *ic) {}
92
93 /*
94 * Write-arounds for common operations.
95 */
96 static __inline void
97 cipher_detach(struct ieee80211_key *key)
98 {
99 key->wk_cipher->ic_detach(key);
100 }
101
102 static __inline void *
103 cipher_attach(struct ieee80211com *ic, struct ieee80211_key *key)
104 {
105 return key->wk_cipher->ic_attach(ic, key);
106 }
107
108 /*
109 * Wrappers for driver key management methods.
110 */
111 static __inline int
112 dev_key_alloc(struct ieee80211com *ic,
113 const struct ieee80211_key *key,
114 ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
115 {
116 return ic->ic_crypto.cs_key_alloc(ic, key, keyix, rxkeyix);
117 }
118
119 static __inline int
120 dev_key_delete(struct ieee80211com *ic,
121 const struct ieee80211_key *key)
122 {
123 return ic->ic_crypto.cs_key_delete(ic, key);
124 }
125
126 static __inline int
127 dev_key_set(struct ieee80211com *ic, const struct ieee80211_key *key,
128 const uint8_t mac[IEEE80211_ADDR_LEN])
129 {
130 return ic->ic_crypto.cs_key_set(ic, key, mac);
131 }
132
133 /*
134 * Setup crypto support.
135 */
136 void
137 ieee80211_crypto_attach(struct ieee80211com *ic)
138 {
139 struct ieee80211_crypto_state *cs = &ic->ic_crypto;
140 int i;
141
142 /* NB: we assume everything is pre-zero'd */
143 cs->cs_def_txkey = IEEE80211_KEYIX_NONE;
144 cs->cs_max_keyix = IEEE80211_WEP_NKID;
145 ciphers[IEEE80211_CIPHER_NONE] = &ieee80211_cipher_none;
146 for (i = 0; i < IEEE80211_WEP_NKID; i++)
147 ieee80211_crypto_resetkey(ic, &cs->cs_nw_keys[i],
148 IEEE80211_KEYIX_NONE);
149 /*
150 * Initialize the driver key support routines to noop entries.
151 * This is useful especially for the cipher test modules.
152 */
153 cs->cs_key_alloc = null_key_alloc;
154 cs->cs_key_set = null_key_set;
155 cs->cs_key_delete = null_key_delete;
156 cs->cs_key_update_begin = null_key_update;
157 cs->cs_key_update_end = null_key_update;
158 }
159
160 /*
161 * Teardown crypto support.
162 */
163 void
164 ieee80211_crypto_detach(struct ieee80211com *ic)
165 {
166 ieee80211_crypto_delglobalkeys(ic);
167 }
168
169 /*
170 * Register a crypto cipher module.
171 */
172 void
173 ieee80211_crypto_register(const struct ieee80211_cipher *cip)
174 {
175 if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
176 printf("%s: cipher %s has an invalid cipher index %u\n",
177 __func__, cip->ic_name, cip->ic_cipher);
178 return;
179 }
180 if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
181 printf("%s: cipher %s registered with a different template\n",
182 __func__, cip->ic_name);
183 return;
184 }
185 ciphers[cip->ic_cipher] = cip;
186 }
187
188 /*
189 * Unregister a crypto cipher module.
190 */
191 void
192 ieee80211_crypto_unregister(const struct ieee80211_cipher *cip)
193 {
194 if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
195 printf("%s: cipher %s has an invalid cipher index %u\n",
196 __func__, cip->ic_name, cip->ic_cipher);
197 return;
198 }
199 if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
200 printf("%s: cipher %s registered with a different template\n",
201 __func__, cip->ic_name);
202 return;
203 }
204 /* NB: don't complain about not being registered */
205 /* XXX disallow if references */
206 ciphers[cip->ic_cipher] = NULL;
207 }
208
209 int
210 ieee80211_crypto_available(u_int cipher)
211 {
212 return cipher < IEEE80211_CIPHER_MAX && ciphers[cipher] != NULL;
213 }
214
215 /* XXX well-known names! */
216 static const char *cipher_modnames[] = {
217 "wlan_wep", /* IEEE80211_CIPHER_WEP */
218 "wlan_tkip", /* IEEE80211_CIPHER_TKIP */
219 "wlan_aes_ocb", /* IEEE80211_CIPHER_AES_OCB */
220 "wlan_ccmp", /* IEEE80211_CIPHER_AES_CCM */
221 "wlan_ckip", /* IEEE80211_CIPHER_CKIP */
222 };
223
224 /*
225 * Establish a relationship between the specified key and cipher
226 * and, if necessary, allocate a hardware index from the driver.
227 * Note that when a fixed key index is required it must be specified
228 * and we blindly assign it w/o consulting the driver (XXX).
229 *
230 * This must be the first call applied to a key; all the other key
231 * routines assume wk_cipher is setup.
232 *
233 * Locking must be handled by the caller using:
234 * ieee80211_key_update_begin(ic);
235 * ieee80211_key_update_end(ic);
236 */
237 int
238 ieee80211_crypto_newkey(struct ieee80211com *ic,
239 int cipher, int flags, struct ieee80211_key *key)
240 {
241 #define N(a) (sizeof(a) / sizeof(a[0]))
242 const struct ieee80211_cipher *cip;
243 ieee80211_keyix keyix, rxkeyix;
244 void *keyctx;
245 int oflags;
246
247 /*
248 * Validate cipher and set reference to cipher routines.
249 */
250 if (cipher >= IEEE80211_CIPHER_MAX) {
251 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
252 "%s: invalid cipher %u\n", __func__, cipher);
253 ic->ic_stats.is_crypto_badcipher++;
254 return 0;
255 }
256 cip = ciphers[cipher];
257 if (cip == NULL) {
258 /*
259 * Auto-load cipher module if we have a well-known name
260 * for it. It might be better to use string names rather
261 * than numbers and craft a module name based on the cipher
262 * name; e.g. wlan_cipher_<cipher-name>.
263 */
264 if (cipher < N(cipher_modnames)) {
265 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
266 "%s: unregistered cipher %u, load module %s\n",
267 __func__, cipher, cipher_modnames[cipher]);
268 ieee80211_load_module(cipher_modnames[cipher]);
269 /*
270 * If cipher module loaded it should immediately
271 * call ieee80211_crypto_register which will fill
272 * in the entry in the ciphers array.
273 */
274 cip = ciphers[cipher];
275 }
276 if (cip == NULL) {
277 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
278 "%s: unable to load cipher %u, module %s\n",
279 __func__, cipher,
280 cipher < N(cipher_modnames) ?
281 cipher_modnames[cipher] : "<unknown>");
282 ic->ic_stats.is_crypto_nocipher++;
283 return 0;
284 }
285 }
286
287 oflags = key->wk_flags;
288 flags &= IEEE80211_KEY_COMMON;
289 /*
290 * If the hardware does not support the cipher then
291 * fallback to a host-based implementation.
292 */
293 if ((ic->ic_caps & (1<<cipher)) == 0) {
294 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
295 "%s: no h/w support for cipher %s, falling back to s/w\n",
296 __func__, cip->ic_name);
297 flags |= IEEE80211_KEY_SWCRYPT;
298 }
299 /*
300 * Hardware TKIP with software MIC is an important
301 * combination; we handle it by flagging each key,
302 * the cipher modules honor it.
303 */
304 if (cipher == IEEE80211_CIPHER_TKIP &&
305 (ic->ic_caps & IEEE80211_C_TKIPMIC) == 0) {
306 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
307 "%s: no h/w support for TKIP MIC, falling back to s/w\n",
308 __func__);
309 flags |= IEEE80211_KEY_SWMIC;
310 }
311
312 /*
313 * Bind cipher to key instance. Note we do this
314 * after checking the device capabilities so the
315 * cipher module can optimize space usage based on
316 * whether or not it needs to do the cipher work.
317 */
318 if (key->wk_cipher != cip || key->wk_flags != flags) {
319 again:
320 /*
321 * Fillin the flags so cipher modules can see s/w
322 * crypto requirements and potentially allocate
323 * different state and/or attach different method
324 * pointers.
325 *
326 * XXX this is not right when s/w crypto fallback
327 * fails and we try to restore previous state.
328 */
329 key->wk_flags = flags;
330 keyctx = cip->ic_attach(ic, key);
331 if (keyctx == NULL) {
332 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
333 "%s: unable to attach cipher %s\n",
334 __func__, cip->ic_name);
335 key->wk_flags = oflags; /* restore old flags */
336 ic->ic_stats.is_crypto_attachfail++;
337 return 0;
338 }
339 cipher_detach(key);
340 key->wk_cipher = cip; /* XXX refcnt? */
341 key->wk_private = keyctx;
342 }
343 /*
344 * Commit to requested usage so driver can see the flags.
345 */
346 key->wk_flags = flags;
347
348 /*
349 * Ask the driver for a key index if we don't have one.
350 * Note that entries in the global key table always have
351 * an index; this means it's safe to call this routine
352 * for these entries just to setup the reference to the
353 * cipher template. Note also that when using software
354 * crypto we also call the driver to give us a key index.
355 */
356 if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
357 if (!dev_key_alloc(ic, key, &keyix, &rxkeyix)) {
358 /*
359 * Driver has no room; fallback to doing crypto
360 * in the host. We change the flags and start the
361 * procedure over. If we get back here then there's
362 * no hope and we bail. Note that this can leave
363 * the key in a inconsistent state if the caller
364 * continues to use it.
365 */
366 if ((key->wk_flags & IEEE80211_KEY_SWCRYPT) == 0) {
367 ic->ic_stats.is_crypto_swfallback++;
368 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
369 "%s: no h/w resources for cipher %s, "
370 "falling back to s/w\n", __func__,
371 cip->ic_name);
372 oflags = key->wk_flags;
373 flags |= IEEE80211_KEY_SWCRYPT;
374 if (cipher == IEEE80211_CIPHER_TKIP)
375 flags |= IEEE80211_KEY_SWMIC;
376 goto again;
377 }
378 ic->ic_stats.is_crypto_keyfail++;
379 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
380 "%s: unable to setup cipher %s\n",
381 __func__, cip->ic_name);
382 return 0;
383 }
384 key->wk_keyix = keyix;
385 key->wk_rxkeyix = rxkeyix;
386 }
387 return 1;
388 #undef N
389 }
390
391 /*
392 * Remove the key (no locking, for internal use).
393 */
394 static int
395 _ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key)
396 {
397 ieee80211_keyix keyix;
398
399 KASSERT(key->wk_cipher != NULL, ("No cipher!"));
400
401 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
402 "%s: %s keyix %u flags 0x%x rsc %ju tsc %ju len %u\n",
403 __func__, key->wk_cipher->ic_name,
404 key->wk_keyix, key->wk_flags,
405 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen);
406
407 keyix = key->wk_keyix;
408 if (keyix != IEEE80211_KEYIX_NONE) {
409 /*
410 * Remove hardware entry.
411 */
412 /* XXX key cache */
413 if (!dev_key_delete(ic, key)) {
414 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
415 "%s: driver did not delete key index %u\n",
416 __func__, keyix);
417 ic->ic_stats.is_crypto_delkey++;
418 /* XXX recovery? */
419 }
420 }
421 cipher_detach(key);
422 memset(key, 0, sizeof(*key));
423 ieee80211_crypto_resetkey(ic, key, IEEE80211_KEYIX_NONE);
424 return 1;
425 }
426
427 /*
428 * Remove the specified key.
429 */
430 int
431 ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key)
432 {
433 int status;
434
435 ieee80211_key_update_begin(ic);
436 status = _ieee80211_crypto_delkey(ic, key);
437 ieee80211_key_update_end(ic);
438 return status;
439 }
440
441 /*
442 * Clear the global key table.
443 */
444 void
445 ieee80211_crypto_delglobalkeys(struct ieee80211com *ic)
446 {
447 int i;
448
449 ieee80211_key_update_begin(ic);
450 for (i = 0; i < IEEE80211_WEP_NKID; i++)
451 (void) _ieee80211_crypto_delkey(ic, &ic->ic_nw_keys[i]);
452 ieee80211_key_update_end(ic);
453 }
454
455 /*
456 * Set the contents of the specified key.
457 *
458 * Locking must be handled by the caller using:
459 * ieee80211_key_update_begin(ic);
460 * ieee80211_key_update_end(ic);
461 */
462 int
463 ieee80211_crypto_setkey(struct ieee80211com *ic, struct ieee80211_key *key,
464 const uint8_t macaddr[IEEE80211_ADDR_LEN])
465 {
466 const struct ieee80211_cipher *cip = key->wk_cipher;
467
468 KASSERT(cip != NULL, ("No cipher!"));
469
470 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
471 "%s: %s keyix %u flags 0x%x mac %s rsc %ju tsc %ju len %u\n",
472 __func__, cip->ic_name, key->wk_keyix,
473 key->wk_flags, ether_sprintf(macaddr),
474 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen);
475
476 /*
477 * Give cipher a chance to validate key contents.
478 * XXX should happen before modifying state.
479 */
480 if (!cip->ic_setkey(key)) {
481 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
482 "%s: cipher %s rejected key index %u len %u flags 0x%x\n",
483 __func__, cip->ic_name, key->wk_keyix,
484 key->wk_keylen, key->wk_flags);
485 ic->ic_stats.is_crypto_setkey_cipher++;
486 return 0;
487 }
488 if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
489 /* XXX nothing allocated, should not happen */
490 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
491 "%s: no key index; should not happen!\n", __func__);
492 ic->ic_stats.is_crypto_setkey_nokey++;
493 return 0;
494 }
495 return dev_key_set(ic, key, macaddr);
496 }
497
498 /*
499 * Add privacy headers appropriate for the specified key.
500 */
501 struct ieee80211_key *
502 ieee80211_crypto_encap(struct ieee80211com *ic,
503 struct ieee80211_node *ni, struct mbuf *m)
504 {
505 struct ieee80211_key *k;
506 struct ieee80211_frame *wh;
507 const struct ieee80211_cipher *cip;
508 uint8_t keyid;
509
510 /*
511 * Multicast traffic always uses the multicast key.
512 * Otherwise if a unicast key is set we use that and
513 * it is always key index 0. When no unicast key is
514 * set we fall back to the default transmit key.
515 */
516 wh = mtod(m, struct ieee80211_frame *);
517 if (IEEE80211_IS_MULTICAST(wh->i_addr1) ||
518 IEEE80211_KEY_UNDEFINED(&ni->ni_ucastkey)) {
519 if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE) {
520 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
521 "[%s] no default transmit key (%s) deftxkey %u\n",
522 ether_sprintf(wh->i_addr1), __func__,
523 ic->ic_def_txkey);
524 ic->ic_stats.is_tx_nodefkey++;
525 return NULL;
526 }
527 keyid = ic->ic_def_txkey;
528 k = &ic->ic_nw_keys[ic->ic_def_txkey];
529 } else {
530 keyid = 0;
531 k = &ni->ni_ucastkey;
532 }
533 cip = k->wk_cipher;
534 return (cip->ic_encap(k, m, keyid<<6) ? k : NULL);
535 }
536
537 /*
538 * Validate and strip privacy headers (and trailer) for a
539 * received frame that has the WEP/Privacy bit set.
540 */
541 struct ieee80211_key *
542 ieee80211_crypto_decap(struct ieee80211com *ic,
543 struct ieee80211_node *ni, struct mbuf *m, int hdrlen)
544 {
545 #define IEEE80211_WEP_HDRLEN (IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN)
546 #define IEEE80211_WEP_MINLEN \
547 (sizeof(struct ieee80211_frame) + \
548 IEEE80211_WEP_HDRLEN + IEEE80211_WEP_CRCLEN)
549 struct ieee80211_key *k;
550 struct ieee80211_frame *wh;
551 const struct ieee80211_cipher *cip;
552 const uint8_t *ivp;
553 uint8_t keyid;
554
555 /* NB: this minimum size data frame could be bigger */
556 if (m->m_pkthdr.len < IEEE80211_WEP_MINLEN) {
557 IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY,
558 "%s: WEP data frame too short, len %u\n",
559 __func__, m->m_pkthdr.len);
560 ic->ic_stats.is_rx_tooshort++; /* XXX need unique stat? */
561 return NULL;
562 }
563
564 /*
565 * Locate the key. If unicast and there is no unicast
566 * key then we fall back to the key id in the header.
567 * This assumes unicast keys are only configured when
568 * the key id in the header is meaningless (typically 0).
569 */
570 wh = mtod(m, struct ieee80211_frame *);
571 ivp = mtod(m, const uint8_t *) + hdrlen; /* XXX contig */
572 keyid = ivp[IEEE80211_WEP_IVLEN];
573 if (IEEE80211_IS_MULTICAST(wh->i_addr1) ||
574 IEEE80211_KEY_UNDEFINED(&ni->ni_ucastkey))
575 k = &ic->ic_nw_keys[keyid >> 6];
576 else
577 k = &ni->ni_ucastkey;
578
579 /*
580 * Insure crypto header is contiguous for all decap work.
581 */
582 cip = k->wk_cipher;
583 if (m->m_len < hdrlen + cip->ic_header &&
584 (m = m_pullup(m, hdrlen + cip->ic_header)) == NULL) {
585 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
586 "[%s] unable to pullup %s header\n",
587 ether_sprintf(wh->i_addr2), cip->ic_name);
588 ic->ic_stats.is_rx_wepfail++; /* XXX */
589 return NULL;
590 }
591
592 return (cip->ic_decap(k, m, hdrlen) ? k : NULL);
593 #undef IEEE80211_WEP_MINLEN
594 #undef IEEE80211_WEP_HDRLEN
595 }
Cache object: 5dedcf502dc67207a33e53882543fd30
|