1/* $NetBSD: ieee80211_crypto.c,v 1.17 2015/08/24 22:21:26 pooka Exp $ */
2/*-
3 * Copyright (c) 2001 Atsushi Onoe
4 * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * Alternatively, this software may be distributed under the terms of the
19 * GNU General Public License ("GPL") version 2 as published by the Free
20 * Software Foundation.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34#include <sys/cdefs.h>
35#ifdef __FreeBSD__
36__FBSDID("$FreeBSD: src/sys/net80211/ieee80211_crypto.c,v 1.12 2005/08/08 18:46:35 sam Exp $");
37#endif
38#ifdef __NetBSD__
39__KERNEL_RCSID(0, "$NetBSD: ieee80211_crypto.c,v 1.17 2015/08/24 22:21:26 pooka Exp $");
40#endif
41
42#ifdef _KERNEL_OPT
43#include "opt_inet.h"
44#endif
45
46/*
47 * IEEE 802.11 generic crypto support.
48 */
49#include <sys/param.h>
50#include <sys/mbuf.h>
51
52#include <sys/socket.h>
53#include <sys/sockio.h>
54#include <sys/endian.h>
55#include <sys/errno.h>
56#include <sys/proc.h>
57#include <sys/sysctl.h>
58
59#include <net/if.h>
60#include <net/if_media.h>
61#include <net/if_arp.h>
62#include <net/if_ether.h>
63#include <net/if_llc.h>
64
65#include <net80211/ieee80211_netbsd.h>
66#include <net80211/ieee80211_var.h>
67
68/*
69 * Table of registered cipher modules.
70 */
71static const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX];
72
73#ifdef INET
74#include <netinet/in.h>
75#include <net/if_ether.h>
76#endif
77
78static int _ieee80211_crypto_delkey(struct ieee80211com *,
79 struct ieee80211_key *);
80
81/*
82 * Default "null" key management routines.
83 */
84static int
85null_key_alloc(struct ieee80211com *ic, const struct ieee80211_key *k,
86 ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
87{
88 if (!(&ic->ic_nw_keys[0] <= k &&
89 k < &ic->ic_nw_keys[IEEE80211_WEP_NKID])) {
90 /*
91 * Not in the global key table, the driver should handle this
92 * by allocating a slot in the h/w key table/cache. In
93 * lieu of that return key slot 0 for any unicast key
94 * request. We disallow the request if this is a group key.
95 * This default policy does the right thing for legacy hardware
96 * with a 4 key table. It also handles devices that pass
97 * packets through untouched when marked with the WEP bit
98 * and key index 0.
99 */
100 if (k->wk_flags & IEEE80211_KEY_GROUP)
101 return 0;
102 *keyix = 0; /* NB: use key index 0 for ucast key */
103 } else {
104 *keyix = k - ic->ic_nw_keys;
105 }
106 *rxkeyix = IEEE80211_KEYIX_NONE; /* XXX maybe *keyix? */
107 return 1;
108}
109static int
110null_key_delete(struct ieee80211com *ic,
111 const struct ieee80211_key *k)
112{
113 return 1;
114}
115static int
116null_key_set(struct ieee80211com *ic,
117 const struct ieee80211_key *k,
118 const u_int8_t mac[IEEE80211_ADDR_LEN])
119{
120 return 1;
121}
122static void null_key_update(struct ieee80211com *ic) {}
123
124/*
125 * Write-arounds for common operations.
126 */
127static __inline void
128cipher_detach(struct ieee80211_key *key)
129{
130 key->wk_cipher->ic_detach(key);
131}
132
133/*
134 * Wrappers for driver key management methods.
135 */
136static __inline int
137dev_key_alloc(struct ieee80211com *ic,
138 const struct ieee80211_key *key,
139 ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
140{
141 return ic->ic_crypto.cs_key_alloc(ic, key, keyix, rxkeyix);
142}
143
144static __inline int
145dev_key_delete(struct ieee80211com *ic,
146 const struct ieee80211_key *key)
147{
148 return ic->ic_crypto.cs_key_delete(ic, key);
149}
150
151static __inline int
152dev_key_set(struct ieee80211com *ic, const struct ieee80211_key *key,
153 const u_int8_t mac[IEEE80211_ADDR_LEN])
154{
155 return ic->ic_crypto.cs_key_set(ic, key, mac);
156}
157
158/*
159 * Setup crypto support.
160 */
161void
162ieee80211_crypto_attach(struct ieee80211com *ic)
163{
164 struct ieee80211_crypto_state *cs = &ic->ic_crypto;
165 int i;
166
167 /* NB: we assume everything is pre-zero'd */
168 cs->cs_def_txkey = IEEE80211_KEYIX_NONE;
169 cs->cs_max_keyix = IEEE80211_WEP_NKID;
170 ciphers[IEEE80211_CIPHER_NONE] = &ieee80211_cipher_none;
171 for (i = 0; i < IEEE80211_WEP_NKID; i++)
172 ieee80211_crypto_resetkey(ic, &cs->cs_nw_keys[i],
173 IEEE80211_KEYIX_NONE);
174 /*
175 * Initialize the driver key support routines to noop entries.
176 * This is useful especially for the cipher test modules.
177 */
178 cs->cs_key_alloc = null_key_alloc;
179 cs->cs_key_set = null_key_set;
180 cs->cs_key_delete = null_key_delete;
181 cs->cs_key_update_begin = null_key_update;
182 cs->cs_key_update_end = null_key_update;
183}
184
185/*
186 * Teardown crypto support.
187 */
188void
189ieee80211_crypto_detach(struct ieee80211com *ic)
190{
191 ieee80211_crypto_delglobalkeys(ic);
192}
193
194/*
195 * Register a crypto cipher module.
196 */
197void
198ieee80211_crypto_register(const struct ieee80211_cipher *cip)
199{
200 if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
201 printf("%s: cipher %s has an invalid cipher index %u\n",
202 __func__, cip->ic_name, cip->ic_cipher);
203 return;
204 }
205 if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
206 printf("%s: cipher %s registered with a different template\n",
207 __func__, cip->ic_name);
208 return;
209 }
210 ciphers[cip->ic_cipher] = cip;
211}
212
213/*
214 * Unregister a crypto cipher module.
215 */
216void
217ieee80211_crypto_unregister(const struct ieee80211_cipher *cip)
218{
219 if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
220 printf("%s: cipher %s has an invalid cipher index %u\n",
221 __func__, cip->ic_name, cip->ic_cipher);
222 return;
223 }
224 if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
225 printf("%s: cipher %s registered with a different template\n",
226 __func__, cip->ic_name);
227 return;
228 }
229 /* NB: don't complain about not being registered */
230 /* XXX disallow if references */
231 ciphers[cip->ic_cipher] = NULL;
232}
233
234int
235ieee80211_crypto_available(u_int cipher)
236{
237 return cipher < IEEE80211_CIPHER_MAX && ciphers[cipher] != NULL;
238}
239
240/* XXX well-known names! */
241static const char *cipher_modnames[] = {
242 "wlan_wep", /* IEEE80211_CIPHER_WEP */
243 "wlan_tkip", /* IEEE80211_CIPHER_TKIP */
244 "wlan_aes_ocb", /* IEEE80211_CIPHER_AES_OCB */
245 "wlan_ccmp", /* IEEE80211_CIPHER_AES_CCM */
246 "wlan_ckip", /* IEEE80211_CIPHER_CKIP */
247};
248
249/*
250 * Establish a relationship between the specified key and cipher
251 * and, if necessary, allocate a hardware index from the driver.
252 * Note that when a fixed key index is required it must be specified
253 * and we blindly assign it w/o consulting the driver (XXX).
254 *
255 * This must be the first call applied to a key; all the other key
256 * routines assume wk_cipher is setup.
257 *
258 * Locking must be handled by the caller using:
259 * ieee80211_key_update_begin(ic);
260 * ieee80211_key_update_end(ic);
261 */
262int
263ieee80211_crypto_newkey(struct ieee80211com *ic,
264 int cipher, int flags, struct ieee80211_key *key)
265{
266#define N(a) (sizeof(a) / sizeof(a[0]))
267 const struct ieee80211_cipher *cip;
268 ieee80211_keyix keyix, rxkeyix;
269 void *keyctx;
270 int oflags;
271
272 /*
273 * Validate cipher and set reference to cipher routines.
274 */
275 if (cipher >= IEEE80211_CIPHER_MAX) {
276 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
277 "%s: invalid cipher %u\n", __func__, cipher);
278 ic->ic_stats.is_crypto_badcipher++;
279 return 0;
280 }
281 cip = ciphers[cipher];
282 if (cip == NULL) {
283 /*
284 * Auto-load cipher module if we have a well-known name
285 * for it. It might be better to use string names rather
286 * than numbers and craft a module name based on the cipher
287 * name; e.g. wlan_cipher_<cipher-name>.
288 */
289 if (cipher < N(cipher_modnames)) {
290 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
291 "%s: unregistered cipher %u, load module %s\n",
292 __func__, cipher, cipher_modnames[cipher]);
293 ieee80211_load_module(cipher_modnames[cipher]);
294 /*
295 * If cipher module loaded it should immediately
296 * call ieee80211_crypto_register which will fill
297 * in the entry in the ciphers array.
298 */
299 cip = ciphers[cipher];
300 }
301 if (cip == NULL) {
302 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
303 "%s: unable to load cipher %u, module %s\n",
304 __func__, cipher,
305 cipher < N(cipher_modnames) ?
306 cipher_modnames[cipher] : "<unknown>");
307 ic->ic_stats.is_crypto_nocipher++;
308 return 0;
309 }
310 }
311
312 oflags = key->wk_flags;
313 flags &= IEEE80211_KEY_COMMON;
314 /*
315 * If the hardware does not support the cipher then
316 * fallback to a host-based implementation.
317 */
318 if ((ic->ic_caps & (1<<cipher)) == 0) {
319 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
320 "%s: no h/w support for cipher %s, falling back to s/w\n",
321 __func__, cip->ic_name);
322 flags |= IEEE80211_KEY_SWCRYPT;
323 }
324 /*
325 * Hardware TKIP with software MIC is an important
326 * combination; we handle it by flagging each key,
327 * the cipher modules honor it.
328 */
329 if (cipher == IEEE80211_CIPHER_TKIP &&
330 (ic->ic_caps & IEEE80211_C_TKIPMIC) == 0) {
331 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
332 "%s: no h/w support for TKIP MIC, falling back to s/w\n",
333 __func__);
334 flags |= IEEE80211_KEY_SWMIC;
335 }
336
337 /*
338 * Bind cipher to key instance. Note we do this
339 * after checking the device capabilities so the
340 * cipher module can optimize space usage based on
341 * whether or not it needs to do the cipher work.
342 */
343 if (key->wk_cipher != cip || key->wk_flags != flags) {
344again:
345 /*
346 * Fillin the flags so cipher modules can see s/w
347 * crypto requirements and potentially allocate
348 * different state and/or attach different method
349 * pointers.
350 *
351 * XXX this is not right when s/w crypto fallback
352 * fails and we try to restore previous state.
353 */
354 key->wk_flags = flags;
355 keyctx = cip->ic_attach(ic, key);
356 if (keyctx == NULL) {
357 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
358 "%s: unable to attach cipher %s\n",
359 __func__, cip->ic_name);
360 key->wk_flags = oflags; /* restore old flags */
361 ic->ic_stats.is_crypto_attachfail++;
362 return 0;
363 }
364 cipher_detach(key);
365 key->wk_cipher = cip; /* XXX refcnt? */
366 key->wk_private = keyctx;
367 }
368 /*
369 * Commit to requested usage so driver can see the flags.
370 */
371 key->wk_flags = flags;
372
373 /*
374 * Ask the driver for a key index if we don't have one.
375 * Note that entries in the global key table always have
376 * an index; this means it's safe to call this routine
377 * for these entries just to setup the reference to the
378 * cipher template. Note also that when using software
379 * crypto we also call the driver to give us a key index.
380 */
381 if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
382 if (!dev_key_alloc(ic, key, &keyix, &rxkeyix)) {
383 /*
384 * Driver has no room; fallback to doing crypto
385 * in the host. We change the flags and start the
386 * procedure over. If we get back here then there's
387 * no hope and we bail. Note that this can leave
388 * the key in a inconsistent state if the caller
389 * continues to use it.
390 */
391 if ((key->wk_flags & IEEE80211_KEY_SWCRYPT) == 0) {
392 ic->ic_stats.is_crypto_swfallback++;
393 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
394 "%s: no h/w resources for cipher %s, "
395 "falling back to s/w\n", __func__,
396 cip->ic_name);
397 oflags = key->wk_flags;
398 flags |= IEEE80211_KEY_SWCRYPT;
399 if (cipher == IEEE80211_CIPHER_TKIP)
400 flags |= IEEE80211_KEY_SWMIC;
401 goto again;
402 }
403 ic->ic_stats.is_crypto_keyfail++;
404 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
405 "%s: unable to setup cipher %s\n",
406 __func__, cip->ic_name);
407 return 0;
408 }
409 key->wk_keyix = keyix;
410 key->wk_rxkeyix = rxkeyix;
411 }
412 return 1;
413#undef N
414}
415
416/*
417 * Remove the key (no locking, for internal use).
418 */
419static int
420_ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key)
421{
422 ieee80211_keyix keyix;
423
424 IASSERT(key->wk_cipher != NULL, ("No cipher!"));
425
426 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
427 "%s: %s keyix %u flags 0x%x rsc %ju tsc %ju len %u\n",
428 __func__, key->wk_cipher->ic_name,
429 key->wk_keyix, key->wk_flags,
430 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen);
431
432 keyix = key->wk_keyix;
433 if (keyix != IEEE80211_KEYIX_NONE) {
434 /*
435 * Remove hardware entry.
436 */
437 /* XXX key cache */
438 if (!dev_key_delete(ic, key)) {
439 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
440 "%s: driver did not delete key index %u\n",
441 __func__, keyix);
442 ic->ic_stats.is_crypto_delkey++;
443 /* XXX recovery? */
444 }
445 }
446 cipher_detach(key);
447 memset(key, 0, sizeof(*key));
448 ieee80211_crypto_resetkey(ic, key, IEEE80211_KEYIX_NONE);
449 return 1;
450}
451
452/*
453 * Remove the specified key.
454 */
455int
456ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key)
457{
458 int status;
459
460 ieee80211_key_update_begin(ic);
461 status = _ieee80211_crypto_delkey(ic, key);
462 ieee80211_key_update_end(ic);
463 return status;
464}
465
466/*
467 * Clear the global key table.
468 */
469void
470ieee80211_crypto_delglobalkeys(struct ieee80211com *ic)
471{
472 int i;
473
474 ieee80211_key_update_begin(ic);
475 for (i = 0; i < IEEE80211_WEP_NKID; i++)
476 (void) _ieee80211_crypto_delkey(ic, &ic->ic_nw_keys[i]);
477 ieee80211_key_update_end(ic);
478}
479
480/*
481 * Set the contents of the specified key.
482 *
483 * Locking must be handled by the caller using:
484 * ieee80211_key_update_begin(ic);
485 * ieee80211_key_update_end(ic);
486 */
487int
488ieee80211_crypto_setkey(struct ieee80211com *ic, struct ieee80211_key *key,
489 const u_int8_t macaddr[IEEE80211_ADDR_LEN])
490{
491 const struct ieee80211_cipher *cip = key->wk_cipher;
492
493 IASSERT(cip != NULL, ("No cipher!"));
494
495 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
496 "%s: %s keyix %u flags 0x%x mac %s rsc %ju tsc %ju len %u\n",
497 __func__, cip->ic_name, key->wk_keyix,
498 key->wk_flags, ether_sprintf(macaddr),
499 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen);
500
501 /*
502 * Give cipher a chance to validate key contents.
503 * XXX should happen before modifying state.
504 */
505 if (!cip->ic_setkey(key)) {
506 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
507 "%s: cipher %s rejected key index %u len %u flags 0x%x\n",
508 __func__, cip->ic_name, key->wk_keyix,
509 key->wk_keylen, key->wk_flags);
510 ic->ic_stats.is_crypto_setkey_cipher++;
511 return 0;
512 }
513 if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
514 /* XXX nothing allocated, should not happen */
515 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
516 "%s: no key index; should not happen!\n", __func__);
517 ic->ic_stats.is_crypto_setkey_nokey++;
518 return 0;
519 }
520 return dev_key_set(ic, key, macaddr);
521}
522
523/*
524 * Add privacy headers appropriate for the specified key.
525 */
526struct ieee80211_key *
527ieee80211_crypto_encap(struct ieee80211com *ic,
528 struct ieee80211_node *ni, struct mbuf *m)
529{
530 struct ieee80211_key *k;
531 struct ieee80211_frame *wh;
532 const struct ieee80211_cipher *cip;
533 u_int8_t keyid;
534
535 /*
536 * Multicast traffic always uses the multicast key.
537 * Otherwise if a unicast key is set we use that and
538 * it is always key index 0. When no unicast key is
539 * set we fall back to the default transmit key.
540 */
541 wh = mtod(m, struct ieee80211_frame *);
542 if (IEEE80211_IS_MULTICAST(wh->i_addr1) ||
543 ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) {
544 if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE) {
545 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
546 "[%s] no default transmit key (%s) deftxkey %u\n",
547 ether_sprintf(wh->i_addr1), __func__,
548 ic->ic_def_txkey);
549 ic->ic_stats.is_tx_nodefkey++;
550 return NULL;
551 }
552 keyid = ic->ic_def_txkey;
553 k = &ic->ic_nw_keys[ic->ic_def_txkey];
554 } else {
555 keyid = 0;
556 k = &ni->ni_ucastkey;
557 }
558 cip = k->wk_cipher;
559 return (cip->ic_encap(k, m, keyid<<6) ? k : NULL);
560}
561
562/*
563 * Validate and strip privacy headers (and trailer) for a
564 * received frame that has the WEP/Privacy bit set.
565 */
566struct ieee80211_key *
567ieee80211_crypto_decap(struct ieee80211com *ic,
568 struct ieee80211_node *ni, struct mbuf *m, int hdrlen)
569{
570#define IEEE80211_WEP_HDRLEN (IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN)
571#define IEEE80211_WEP_MINLEN \
572 (sizeof(struct ieee80211_frame) + \
573 IEEE80211_WEP_HDRLEN + IEEE80211_WEP_CRCLEN)
574 struct ieee80211_key *k;
575 struct ieee80211_frame *wh;
576 const struct ieee80211_cipher *cip;
577 u_int8_t keyid;
578
579 /* NB: this minimum size data frame could be bigger */
580 if (m->m_pkthdr.len < IEEE80211_WEP_MINLEN) {
581 IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY,
582 "%s: WEP data frame too short, len %u\n",
583 __func__, m->m_pkthdr.len);
584 ic->ic_stats.is_rx_tooshort++; /* XXX need unique stat? */
585 return NULL;
586 }
587
588 /*
589 * Locate the key. If unicast and there is no unicast
590 * key then we fall back to the key id in the header.
591 * This assumes unicast keys are only configured when
592 * the key id in the header is meaningless (typically 0).
593 */
594 wh = mtod(m, struct ieee80211_frame *);
595 m_copydata(m, hdrlen + IEEE80211_WEP_IVLEN, sizeof(keyid), &keyid);
596 if (IEEE80211_IS_MULTICAST(wh->i_addr1) ||
597 ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none)
598 k = &ic->ic_nw_keys[keyid >> 6];
599 else
600 k = &ni->ni_ucastkey;
601
602 /*
603 * Insure crypto header is contiguous for all decap work.
604 */
605 cip = k->wk_cipher;
606 if (m->m_len < hdrlen + cip->ic_header &&
607 (m = m_pullup(m, hdrlen + cip->ic_header)) == NULL) {
608 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
609 "[%s] unable to pullup %s header\n",
610 ether_sprintf(wh->i_addr2), cip->ic_name);
611 ic->ic_stats.is_rx_wepfail++; /* XXX */
612 return NULL;
613 }
614
615 return (cip->ic_decap(k, m, hdrlen) ? k : NULL);
616#undef IEEE80211_WEP_MINLEN
617#undef IEEE80211_WEP_HDRLEN
618}
619