1 /* $NetBSD: ieee80211_crypto.c,v 1.7 2005/06/22 06:16:02 dyoung 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 1.7 2004/12/31 22:42:38 sam Exp $"); 37 #endif 38 #ifdef __NetBSD__ 39 __KERNEL_RCSID(0, "$NetBSD: ieee80211_crypto.c,v 1.7 2005/06/22 06:16:02 dyoung Exp $"); 40 #endif 41 42 #include "opt_inet.h" 43 44 /* 45 * IEEE 802.11 generic crypto support. 46 */ 47 #include <sys/param.h> 48 #include <sys/mbuf.h> 49 50 #include <sys/socket.h> 51 #include <sys/sockio.h> 52 #include <sys/endian.h> 53 #include <sys/errno.h> 54 #include <sys/proc.h> 55 #include <sys/sysctl.h> 56 57 #include <net/if.h> 58 #include <net/if_media.h> 59 #include <net/if_arp.h> 60 #include <net/if_ether.h> 61 #include <net/if_llc.h> 62 63 #include <net80211/ieee80211_netbsd.h> 64 #include <net80211/ieee80211_var.h> 65 66 /* 67 * Table of registered cipher modules. 68 */ 69 static const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX]; 70 71 #ifdef INET 72 #include <netinet/in.h> 73 #include <net/if_ether.h> 74 #endif 75 76 #include <crypto/arc4/arc4.h> /* XXX unneeded? */ 77 static int _ieee80211_crypto_delkey(struct ieee80211com *, 78 struct ieee80211_key *); 79 80 /* 81 * Default "null" key management routines. 82 */ 83 static int 84 null_key_alloc(struct ieee80211com *ic, const struct ieee80211_key *k) 85 { 86 return IEEE80211_KEYIX_NONE; 87 } 88 static int 89 null_key_delete(struct ieee80211com *ic, const struct ieee80211_key *k) 90 { 91 return 1; 92 } 93 static int 94 null_key_set(struct ieee80211com *ic, const struct ieee80211_key *k, 95 const u_int8_t mac[IEEE80211_ADDR_LEN]) 96 { 97 return 1; 98 } 99 static void null_key_update(struct ieee80211com *ic) {} 100 101 /* 102 * Write-arounds for common operations. 103 */ 104 static __inline void 105 cipher_detach(struct ieee80211_key *key) 106 { 107 key->wk_cipher->ic_detach(key); 108 } 109 110 static __inline void * 111 cipher_attach(struct ieee80211com *ic, struct ieee80211_key *key) 112 { 113 return key->wk_cipher->ic_attach(ic, key); 114 } 115 116 /* 117 * Wrappers for driver key management methods. 118 */ 119 static __inline int 120 dev_key_alloc(struct ieee80211com *ic, 121 const struct ieee80211_key *key) 122 { 123 return ic->ic_crypto.cs_key_alloc(ic, key); 124 } 125 126 static __inline int 127 dev_key_delete(struct ieee80211com *ic, 128 const struct ieee80211_key *key) 129 { 130 return ic->ic_crypto.cs_key_delete(ic, key); 131 } 132 133 static __inline int 134 dev_key_set(struct ieee80211com *ic, const struct ieee80211_key *key, 135 const u_int8_t mac[IEEE80211_ADDR_LEN]) 136 { 137 return ic->ic_crypto.cs_key_set(ic, key, mac); 138 } 139 140 /* 141 * Setup crypto support. 142 */ 143 void 144 ieee80211_crypto_attach(struct ieee80211com *ic) 145 { 146 struct ieee80211_crypto_state *cs = &ic->ic_crypto; 147 int i; 148 149 /* NB: we assume everything is pre-zero'd */ 150 cs->cs_def_txkey = IEEE80211_KEYIX_NONE; 151 ciphers[IEEE80211_CIPHER_AES_CCM] = &ieee80211_cipher_ccmp; 152 ciphers[IEEE80211_CIPHER_TKIP] = &ieee80211_cipher_tkip; 153 ciphers[IEEE80211_CIPHER_WEP] = &ieee80211_cipher_wep; 154 ciphers[IEEE80211_CIPHER_NONE] = &ieee80211_cipher_none; 155 156 for (i = 0; i < IEEE80211_WEP_NKID; i++) 157 ieee80211_crypto_resetkey(ic, &cs->cs_nw_keys[i], 158 IEEE80211_KEYIX_NONE); 159 /* 160 * Initialize the driver key support routines to noop entries. 161 * This is useful especially for the cipher test modules. 162 */ 163 cs->cs_key_alloc = null_key_alloc; 164 cs->cs_key_set = null_key_set; 165 cs->cs_key_delete = null_key_delete; 166 cs->cs_key_update_begin = null_key_update; 167 cs->cs_key_update_end = null_key_update; 168 } 169 170 /* 171 * Teardown crypto support. 172 */ 173 void 174 ieee80211_crypto_detach(struct ieee80211com *ic) 175 { 176 ieee80211_crypto_delglobalkeys(ic); 177 } 178 179 /* 180 * Register a crypto cipher module. 181 */ 182 void 183 ieee80211_crypto_register(const struct ieee80211_cipher *cip) 184 { 185 if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) { 186 printf("%s: cipher %s has an invalid cipher index %u\n", 187 __func__, cip->ic_name, cip->ic_cipher); 188 return; 189 } 190 if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) { 191 printf("%s: cipher %s registered with a different template\n", 192 __func__, cip->ic_name); 193 return; 194 } 195 ciphers[cip->ic_cipher] = cip; 196 } 197 198 /* 199 * Unregister a crypto cipher module. 200 */ 201 void 202 ieee80211_crypto_unregister(const struct ieee80211_cipher *cip) 203 { 204 if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) { 205 printf("%s: cipher %s has an invalid cipher index %u\n", 206 __func__, cip->ic_name, cip->ic_cipher); 207 return; 208 } 209 if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) { 210 printf("%s: cipher %s registered with a different template\n", 211 __func__, cip->ic_name); 212 return; 213 } 214 /* NB: don't complain about not being registered */ 215 /* XXX disallow if references */ 216 ciphers[cip->ic_cipher] = NULL; 217 } 218 219 int 220 ieee80211_crypto_available(u_int cipher) 221 { 222 return cipher < IEEE80211_CIPHER_MAX && ciphers[cipher] != NULL; 223 } 224 225 /* XXX well-known names! */ 226 static const char *cipher_modnames[] = { 227 "wlan_wep", /* IEEE80211_CIPHER_WEP */ 228 "wlan_tkip", /* IEEE80211_CIPHER_TKIP */ 229 "wlan_aes_ocb", /* IEEE80211_CIPHER_AES_OCB */ 230 "wlan_ccmp", /* IEEE80211_CIPHER_AES_CCM */ 231 "wlan_ckip", /* IEEE80211_CIPHER_CKIP */ 232 }; 233 234 /* 235 * Establish a relationship between the specified key and cipher 236 * and, if necessary, allocate a hardware index from the driver. 237 * Note that when a fixed key index is required it must be specified 238 * and we blindly assign it w/o consulting the driver (XXX). 239 * 240 * This must be the first call applied to a key; all the other key 241 * routines assume wk_cipher is setup. 242 * 243 * Locking must be handled by the caller using: 244 * ieee80211_key_update_begin(ic); 245 * ieee80211_key_update_end(ic); 246 */ 247 int 248 ieee80211_crypto_newkey(struct ieee80211com *ic, 249 int cipher, int flags, struct ieee80211_key *key) 250 { 251 #define N(a) (sizeof(a) / sizeof(a[0])) 252 const struct ieee80211_cipher *cip; 253 void *keyctx; 254 int oflags; 255 256 /* 257 * Validate cipher and set reference to cipher routines. 258 */ 259 if (cipher >= IEEE80211_CIPHER_MAX) { 260 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 261 "%s: invalid cipher %u\n", __func__, cipher); 262 ic->ic_stats.is_crypto_badcipher++; 263 return 0; 264 } 265 cip = ciphers[cipher]; 266 if (cip == NULL) { 267 /* 268 * Auto-load cipher module if we have a well-known name 269 * for it. It might be better to use string names rather 270 * than numbers and craft a module name based on the cipher 271 * name; e.g. wlan_cipher_<cipher-name>. 272 */ 273 if (cipher < N(cipher_modnames)) { 274 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 275 "%s: unregistered cipher %u, load module %s\n", 276 __func__, cipher, cipher_modnames[cipher]); 277 ieee80211_load_module(cipher_modnames[cipher]); 278 /* 279 * If cipher module loaded it should immediately 280 * call ieee80211_crypto_register which will fill 281 * in the entry in the ciphers array. 282 */ 283 cip = ciphers[cipher]; 284 } 285 if (cip == NULL) { 286 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 287 "%s: unable to load cipher %u, module %s\n", 288 __func__, cipher, 289 cipher < N(cipher_modnames) ? 290 cipher_modnames[cipher] : "<unknown>"); 291 ic->ic_stats.is_crypto_nocipher++; 292 return 0; 293 } 294 } 295 296 oflags = key->wk_flags; 297 flags &= IEEE80211_KEY_COMMON; 298 /* 299 * If the hardware does not support the cipher then 300 * fallback to a host-based implementation. 301 */ 302 if ((ic->ic_caps & (1<<cipher)) == 0) { 303 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 304 "%s: no h/w support for cipher %s, falling back to s/w\n", 305 __func__, cip->ic_name); 306 flags |= IEEE80211_KEY_SWCRYPT; 307 } 308 /* 309 * Hardware TKIP with software MIC is an important 310 * combination; we handle it by flagging each key, 311 * the cipher modules honor it. 312 */ 313 if (cipher == IEEE80211_CIPHER_TKIP && 314 (ic->ic_caps & IEEE80211_C_TKIPMIC) == 0) { 315 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 316 "%s: no h/w support for TKIP MIC, falling back to s/w\n", 317 __func__); 318 flags |= IEEE80211_KEY_SWMIC; 319 } 320 321 /* 322 * Bind cipher to key instance. Note we do this 323 * after checking the device capabilities so the 324 * cipher module can optimize space usage based on 325 * whether or not it needs to do the cipher work. 326 */ 327 if (key->wk_cipher != cip || key->wk_flags != flags) { 328 again: 329 /* 330 * Fillin the flags so cipher modules can see s/w 331 * crypto requirements and potentially allocate 332 * different state and/or attach different method 333 * pointers. 334 * 335 * XXX this is not right when s/w crypto fallback 336 * fails and we try to restore previous state. 337 */ 338 key->wk_flags = flags; 339 keyctx = cip->ic_attach(ic, key); 340 if (keyctx == NULL) { 341 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 342 "%s: unable to attach cipher %s\n", 343 __func__, cip->ic_name); 344 key->wk_flags = oflags; /* restore old flags */ 345 ic->ic_stats.is_crypto_attachfail++; 346 return 0; 347 } 348 cipher_detach(key); 349 key->wk_cipher = cip; /* XXX refcnt? */ 350 key->wk_private = keyctx; 351 } 352 /* 353 * Commit to requested usage so driver can see the flags. 354 */ 355 key->wk_flags = flags; 356 357 /* 358 * Ask the driver for a key index if we don't have one. 359 * Note that entries in the global key table always have 360 * an index; this means it's safe to call this routine 361 * for these entries just to setup the reference to the 362 * cipher template. Note also that when using software 363 * crypto we also call the driver to give us a key index. 364 */ 365 if (key->wk_keyix == IEEE80211_KEYIX_NONE) { 366 key->wk_keyix = dev_key_alloc(ic, key); 367 if (key->wk_keyix == IEEE80211_KEYIX_NONE) { 368 /* 369 * Driver has no room; fallback to doing crypto 370 * in the host. We change the flags and start the 371 * procedure over. If we get back here then there's 372 * no hope and we bail. Note that this can leave 373 * the key in a inconsistent state if the caller 374 * continues to use it. 375 */ 376 if ((key->wk_flags & IEEE80211_KEY_SWCRYPT) == 0) { 377 ic->ic_stats.is_crypto_swfallback++; 378 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 379 "%s: no h/w resources for cipher %s, " 380 "falling back to s/w\n", __func__, 381 cip->ic_name); 382 oflags = key->wk_flags; 383 flags |= IEEE80211_KEY_SWCRYPT; 384 if (cipher == IEEE80211_CIPHER_TKIP) 385 flags |= IEEE80211_KEY_SWMIC; 386 goto again; 387 } 388 ic->ic_stats.is_crypto_keyfail++; 389 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 390 "%s: unable to setup cipher %s\n", 391 __func__, cip->ic_name); 392 return 0; 393 } 394 } 395 return 1; 396 #undef N 397 } 398 399 /* 400 * Remove the key (no locking, for internal use). 401 */ 402 static int 403 _ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key) 404 { 405 u_int16_t keyix; 406 407 IASSERT(key->wk_cipher != NULL, ("No cipher!")); 408 409 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 410 "%s: %s keyix %u flags 0x%x rsc %ju tsc %ju len %u\n", 411 __func__, key->wk_cipher->ic_name, 412 key->wk_keyix, key->wk_flags, 413 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen); 414 415 keyix = key->wk_keyix; 416 if (keyix != IEEE80211_KEYIX_NONE) { 417 /* 418 * Remove hardware entry. 419 */ 420 /* XXX key cache */ 421 if (!dev_key_delete(ic, key)) { 422 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 423 "%s: driver did not delete key index %u\n", 424 __func__, keyix); 425 ic->ic_stats.is_crypto_delkey++; 426 /* XXX recovery? */ 427 } 428 } 429 cipher_detach(key); 430 memset(key, 0, sizeof(*key)); 431 ieee80211_crypto_resetkey(ic, key, IEEE80211_KEYIX_NONE); 432 return 1; 433 } 434 435 /* 436 * Remove the specified key. 437 */ 438 int 439 ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key) 440 { 441 int status; 442 443 ieee80211_key_update_begin(ic); 444 status = _ieee80211_crypto_delkey(ic, key); 445 ieee80211_key_update_end(ic); 446 return status; 447 } 448 449 /* 450 * Clear the global key table. 451 */ 452 void 453 ieee80211_crypto_delglobalkeys(struct ieee80211com *ic) 454 { 455 int i; 456 457 ieee80211_key_update_begin(ic); 458 for (i = 0; i < IEEE80211_WEP_NKID; i++) 459 (void) _ieee80211_crypto_delkey(ic, &ic->ic_nw_keys[i]); 460 ieee80211_key_update_end(ic); 461 } 462 463 /* 464 * Set the contents of the specified key. 465 * 466 * Locking must be handled by the caller using: 467 * ieee80211_key_update_begin(ic); 468 * ieee80211_key_update_end(ic); 469 */ 470 int 471 ieee80211_crypto_setkey(struct ieee80211com *ic, struct ieee80211_key *key, 472 const u_int8_t macaddr[IEEE80211_ADDR_LEN]) 473 { 474 const struct ieee80211_cipher *cip = key->wk_cipher; 475 476 IASSERT(cip != NULL, ("No cipher!")); 477 478 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 479 "%s: %s keyix %u flags 0x%x mac %s rsc %ju tsc %ju len %u\n", 480 __func__, cip->ic_name, key->wk_keyix, 481 key->wk_flags, ether_sprintf(macaddr), 482 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen); 483 484 /* 485 * Give cipher a chance to validate key contents. 486 * XXX should happen before modifying state. 487 */ 488 if (!cip->ic_setkey(key)) { 489 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 490 "%s: cipher %s rejected key index %u len %u flags 0x%x\n", 491 __func__, cip->ic_name, key->wk_keyix, 492 key->wk_keylen, key->wk_flags); 493 ic->ic_stats.is_crypto_setkey_cipher++; 494 return 0; 495 } 496 if (key->wk_keyix == IEEE80211_KEYIX_NONE) { 497 /* XXX nothing allocated, should not happen */ 498 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 499 "%s: no key index; should not happen!\n", __func__); 500 ic->ic_stats.is_crypto_setkey_nokey++; 501 return 0; 502 } 503 return dev_key_set(ic, key, macaddr); 504 } 505 506 /* 507 * Add privacy headers appropriate for the specified key. 508 */ 509 struct ieee80211_key * 510 ieee80211_crypto_encap(struct ieee80211com *ic, 511 struct ieee80211_node *ni, struct mbuf *m) 512 { 513 struct ieee80211_key *k; 514 struct ieee80211_frame *wh; 515 const struct ieee80211_cipher *cip; 516 u_int8_t keyid; 517 518 /* 519 * Multicast traffic always uses the multicast key. 520 * Otherwise if a unicast key is set we use that and 521 * it is always key index 0. When no unicast key is 522 * set we fall back to the default transmit key. 523 */ 524 wh = mtod(m, struct ieee80211_frame *); 525 if (IEEE80211_IS_MULTICAST(wh->i_addr1) || 526 ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) { 527 if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE) { 528 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 529 "[%s] no default transmit key (%s) deftxkey %u\n", 530 ether_sprintf(wh->i_addr1), __func__, 531 ic->ic_def_txkey); 532 ic->ic_stats.is_tx_nodefkey++; 533 goto bad; 534 } 535 keyid = ic->ic_def_txkey; 536 k = &ic->ic_nw_keys[ic->ic_def_txkey]; 537 } else { 538 keyid = 0; 539 k = &ni->ni_ucastkey; 540 } 541 cip = k->wk_cipher; 542 if (cip->ic_encap(k, m, keyid<<6)) 543 return k; 544 bad: 545 m_freem(m); 546 return NULL; 547 } 548 549 /* 550 * Validate and strip privacy headers (and trailer) for a 551 * received frame that has the WEP/Privacy bit set. 552 */ 553 struct ieee80211_key * 554 ieee80211_crypto_decap(struct ieee80211com *ic, 555 struct ieee80211_node *ni, struct mbuf *m) 556 { 557 #define IEEE80211_WEP_HDRLEN (IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN) 558 #define IEEE80211_WEP_MINLEN \ 559 (sizeof(struct ieee80211_frame) + ETHER_HDR_LEN + \ 560 IEEE80211_WEP_HDRLEN + IEEE80211_WEP_CRCLEN) 561 struct ieee80211_key *k; 562 struct ieee80211_frame *wh; 563 const struct ieee80211_cipher *cip; 564 const u_int8_t *ivp; 565 u_int8_t keyid; 566 int hdrlen; 567 568 /* NB: this minimum size data frame could be bigger */ 569 if (m->m_pkthdr.len < IEEE80211_WEP_MINLEN) { 570 IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY, 571 "%s: WEP data frame too short, len %u\n", 572 __func__, m->m_pkthdr.len); 573 ic->ic_stats.is_rx_tooshort++; /* XXX need unique stat? */ 574 return NULL; 575 } 576 577 /* 578 * Locate the key. If unicast and there is no unicast 579 * key then we fall back to the key id in the header. 580 * This assumes unicast keys are only configured when 581 * the key id in the header is meaningless (typically 0). 582 */ 583 wh = mtod(m, struct ieee80211_frame *); 584 hdrlen = ieee80211_hdrsize(wh); 585 ivp = mtod(m, const u_int8_t *) + hdrlen; /* XXX contig */ 586 keyid = ivp[IEEE80211_WEP_IVLEN]; 587 if (IEEE80211_IS_MULTICAST(wh->i_addr1) || 588 ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) 589 k = &ic->ic_nw_keys[keyid >> 6]; 590 else 591 k = &ni->ni_ucastkey; 592 593 /* 594 * Insure crypto header is contiguous for all decap work. 595 */ 596 cip = k->wk_cipher; 597 if (m->m_len < hdrlen + cip->ic_header && 598 (m = m_pullup(m, hdrlen + cip->ic_header)) == NULL) { 599 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 600 "[%s] unable to pullup %s header\n", 601 ether_sprintf(wh->i_addr2), cip->ic_name); 602 ic->ic_stats.is_rx_wepfail++; /* XXX */ 603 return 0; 604 } 605 606 return (cip->ic_decap(k, m) ? k : NULL); 607 #undef IEEE80211_WEP_MINLEN 608 #undef IEEE80211_WEP_HDRLEN 609 } 610