ieee80211_crypto.c revision 148303
1/*- 2 * Copyright (c) 2001 Atsushi Onoe 3 * Copyright (c) 2002-2005 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 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * Alternatively, this software may be distributed under the terms of the 18 * GNU General Public License ("GPL") version 2 as published by the Free 19 * Software Foundation. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33#include <sys/cdefs.h> 34__FBSDID("$FreeBSD: head/sys/net80211/ieee80211_crypto.c 148303 2005-07-22 17:42:08Z sam $"); 35 36/* 37 * IEEE 802.11 generic crypto support. 38 */ 39#include <sys/param.h> 40#include <sys/mbuf.h> 41 42#include <sys/socket.h> 43 44#include <net/if.h> 45#include <net/if_media.h> 46#include <net/ethernet.h> /* XXX ETHER_HDR_LEN */ 47 48#include <net80211/ieee80211_var.h> 49 50/* 51 * Table of registered cipher modules. 52 */ 53static const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX]; 54 55static int _ieee80211_crypto_delkey(struct ieee80211com *, 56 struct ieee80211_key *); 57 58/* 59 * Default "null" key management routines. 60 */ 61static int 62null_key_alloc(struct ieee80211com *ic, const struct ieee80211_key *k) 63{ 64 if (!(&ic->ic_nw_keys[0] <= k && 65 k < &ic->ic_nw_keys[IEEE80211_WEP_NKID])) { 66 /* 67 * Not in the global key table, the driver should handle this 68 * by allocating a slot in the h/w key table/cache. In 69 * lieu of that return key slot 0 for any unicast key 70 * request. We disallow the request if this is a group key. 71 * This default policy does the right thing for legacy hardware 72 * with a 4 key table. It also handles devices that pass 73 * packets through untouched when marked with the WEP bit 74 * and key index 0. 75 */ 76 if ((k->wk_flags & IEEE80211_KEY_GROUP) == 0) 77 return 0; /* NB: use key index 0 for ucast key */ 78 else 79 return IEEE80211_KEYIX_NONE; 80 } 81 return k - ic->ic_nw_keys; 82} 83static int 84null_key_delete(struct ieee80211com *ic, const struct ieee80211_key *k) 85{ 86 return 1; 87} 88static int 89null_key_set(struct ieee80211com *ic, const struct ieee80211_key *k, 90 const u_int8_t mac[IEEE80211_ADDR_LEN]) 91{ 92 return 1; 93} 94static void null_key_update(struct ieee80211com *ic) {} 95 96/* 97 * Write-arounds for common operations. 98 */ 99static __inline void 100cipher_detach(struct ieee80211_key *key) 101{ 102 key->wk_cipher->ic_detach(key); 103} 104 105static __inline void * 106cipher_attach(struct ieee80211com *ic, struct ieee80211_key *key) 107{ 108 return key->wk_cipher->ic_attach(ic, key); 109} 110 111/* 112 * Wrappers for driver key management methods. 113 */ 114static __inline int 115dev_key_alloc(struct ieee80211com *ic, 116 const struct ieee80211_key *key) 117{ 118 return ic->ic_crypto.cs_key_alloc(ic, key); 119} 120 121static __inline int 122dev_key_delete(struct ieee80211com *ic, 123 const struct ieee80211_key *key) 124{ 125 return ic->ic_crypto.cs_key_delete(ic, key); 126} 127 128static __inline int 129dev_key_set(struct ieee80211com *ic, const struct ieee80211_key *key, 130 const u_int8_t mac[IEEE80211_ADDR_LEN]) 131{ 132 return ic->ic_crypto.cs_key_set(ic, key, mac); 133} 134 135/* 136 * Setup crypto support. 137 */ 138void 139ieee80211_crypto_attach(struct ieee80211com *ic) 140{ 141 struct ieee80211_crypto_state *cs = &ic->ic_crypto; 142 int i; 143 144 /* NB: we assume everything is pre-zero'd */ 145 cs->cs_def_txkey = IEEE80211_KEYIX_NONE; 146 ciphers[IEEE80211_CIPHER_NONE] = &ieee80211_cipher_none; 147 for (i = 0; i < IEEE80211_WEP_NKID; i++) 148 ieee80211_crypto_resetkey(ic, &cs->cs_nw_keys[i], 149 IEEE80211_KEYIX_NONE); 150 /* 151 * Initialize the driver key support routines to noop entries. 152 * This is useful especially for the cipher test modules. 153 */ 154 cs->cs_key_alloc = null_key_alloc; 155 cs->cs_key_set = null_key_set; 156 cs->cs_key_delete = null_key_delete; 157 cs->cs_key_update_begin = null_key_update; 158 cs->cs_key_update_end = null_key_update; 159} 160 161/* 162 * Teardown crypto support. 163 */ 164void 165ieee80211_crypto_detach(struct ieee80211com *ic) 166{ 167 ieee80211_crypto_delglobalkeys(ic); 168} 169 170/* 171 * Register a crypto cipher module. 172 */ 173void 174ieee80211_crypto_register(const struct ieee80211_cipher *cip) 175{ 176 if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) { 177 printf("%s: cipher %s has an invalid cipher index %u\n", 178 __func__, cip->ic_name, cip->ic_cipher); 179 return; 180 } 181 if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) { 182 printf("%s: cipher %s registered with a different template\n", 183 __func__, cip->ic_name); 184 return; 185 } 186 ciphers[cip->ic_cipher] = cip; 187} 188 189/* 190 * Unregister a crypto cipher module. 191 */ 192void 193ieee80211_crypto_unregister(const struct ieee80211_cipher *cip) 194{ 195 if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) { 196 printf("%s: cipher %s has an invalid cipher index %u\n", 197 __func__, cip->ic_name, cip->ic_cipher); 198 return; 199 } 200 if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) { 201 printf("%s: cipher %s registered with a different template\n", 202 __func__, cip->ic_name); 203 return; 204 } 205 /* NB: don't complain about not being registered */ 206 /* XXX disallow if references */ 207 ciphers[cip->ic_cipher] = NULL; 208} 209 210int 211ieee80211_crypto_available(u_int cipher) 212{ 213 return cipher < IEEE80211_CIPHER_MAX && ciphers[cipher] != NULL; 214} 215 216/* XXX well-known names! */ 217static const char *cipher_modnames[] = { 218 "wlan_wep", /* IEEE80211_CIPHER_WEP */ 219 "wlan_tkip", /* IEEE80211_CIPHER_TKIP */ 220 "wlan_aes_ocb", /* IEEE80211_CIPHER_AES_OCB */ 221 "wlan_ccmp", /* IEEE80211_CIPHER_AES_CCM */ 222 "wlan_ckip", /* IEEE80211_CIPHER_CKIP */ 223}; 224 225/* 226 * Establish a relationship between the specified key and cipher 227 * and, if necessary, allocate a hardware index from the driver. 228 * Note that when a fixed key index is required it must be specified 229 * and we blindly assign it w/o consulting the driver (XXX). 230 * 231 * This must be the first call applied to a key; all the other key 232 * routines assume wk_cipher is setup. 233 * 234 * Locking must be handled by the caller using: 235 * ieee80211_key_update_begin(ic); 236 * ieee80211_key_update_end(ic); 237 */ 238int 239ieee80211_crypto_newkey(struct ieee80211com *ic, 240 int cipher, int flags, struct ieee80211_key *key) 241{ 242#define N(a) (sizeof(a) / sizeof(a[0])) 243 const struct ieee80211_cipher *cip; 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) { 319again: 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 key->wk_keyix = dev_key_alloc(ic, key); 358 if (key->wk_keyix == IEEE80211_KEYIX_NONE) { 359 /* 360 * Driver has no room; fallback to doing crypto 361 * in the host. We change the flags and start the 362 * procedure over. If we get back here then there's 363 * no hope and we bail. Note that this can leave 364 * the key in a inconsistent state if the caller 365 * continues to use it. 366 */ 367 if ((key->wk_flags & IEEE80211_KEY_SWCRYPT) == 0) { 368 ic->ic_stats.is_crypto_swfallback++; 369 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 370 "%s: no h/w resources for cipher %s, " 371 "falling back to s/w\n", __func__, 372 cip->ic_name); 373 oflags = key->wk_flags; 374 flags |= IEEE80211_KEY_SWCRYPT; 375 if (cipher == IEEE80211_CIPHER_TKIP) 376 flags |= IEEE80211_KEY_SWMIC; 377 goto again; 378 } 379 ic->ic_stats.is_crypto_keyfail++; 380 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 381 "%s: unable to setup cipher %s\n", 382 __func__, cip->ic_name); 383 return 0; 384 } 385 } 386 return 1; 387#undef N 388} 389 390/* 391 * Remove the key (no locking, for internal use). 392 */ 393static int 394_ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key) 395{ 396 u_int16_t keyix; 397 398 KASSERT(key->wk_cipher != NULL, ("No cipher!")); 399 400 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 401 "%s: %s keyix %u flags 0x%x rsc %ju tsc %ju len %u\n", 402 __func__, key->wk_cipher->ic_name, 403 key->wk_keyix, key->wk_flags, 404 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen); 405 406 keyix = key->wk_keyix; 407 if (keyix != IEEE80211_KEYIX_NONE) { 408 /* 409 * Remove hardware entry. 410 */ 411 /* XXX key cache */ 412 if (!dev_key_delete(ic, key)) { 413 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 414 "%s: driver did not delete key index %u\n", 415 __func__, keyix); 416 ic->ic_stats.is_crypto_delkey++; 417 /* XXX recovery? */ 418 } 419 } 420 cipher_detach(key); 421 memset(key, 0, sizeof(*key)); 422 ieee80211_crypto_resetkey(ic, key, IEEE80211_KEYIX_NONE); 423 return 1; 424} 425 426/* 427 * Remove the specified key. 428 */ 429int 430ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key) 431{ 432 int status; 433 434 ieee80211_key_update_begin(ic); 435 status = _ieee80211_crypto_delkey(ic, key); 436 ieee80211_key_update_end(ic); 437 return status; 438} 439 440/* 441 * Clear the global key table. 442 */ 443void 444ieee80211_crypto_delglobalkeys(struct ieee80211com *ic) 445{ 446 int i; 447 448 ieee80211_key_update_begin(ic); 449 for (i = 0; i < IEEE80211_WEP_NKID; i++) 450 (void) _ieee80211_crypto_delkey(ic, &ic->ic_nw_keys[i]); 451 ieee80211_key_update_end(ic); 452} 453 454/* 455 * Set the contents of the specified key. 456 * 457 * Locking must be handled by the caller using: 458 * ieee80211_key_update_begin(ic); 459 * ieee80211_key_update_end(ic); 460 */ 461int 462ieee80211_crypto_setkey(struct ieee80211com *ic, struct ieee80211_key *key, 463 const u_int8_t macaddr[IEEE80211_ADDR_LEN]) 464{ 465 const struct ieee80211_cipher *cip = key->wk_cipher; 466 467 KASSERT(cip != NULL, ("No cipher!")); 468 469 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 470 "%s: %s keyix %u flags 0x%x mac %s rsc %ju tsc %ju len %u\n", 471 __func__, cip->ic_name, key->wk_keyix, 472 key->wk_flags, ether_sprintf(macaddr), 473 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen); 474 475 /* 476 * Give cipher a chance to validate key contents. 477 * XXX should happen before modifying state. 478 */ 479 if (!cip->ic_setkey(key)) { 480 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 481 "%s: cipher %s rejected key index %u len %u flags 0x%x\n", 482 __func__, cip->ic_name, key->wk_keyix, 483 key->wk_keylen, key->wk_flags); 484 ic->ic_stats.is_crypto_setkey_cipher++; 485 return 0; 486 } 487 if (key->wk_keyix == IEEE80211_KEYIX_NONE) { 488 /* XXX nothing allocated, should not happen */ 489 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 490 "%s: no key index; should not happen!\n", __func__); 491 ic->ic_stats.is_crypto_setkey_nokey++; 492 return 0; 493 } 494 return dev_key_set(ic, key, macaddr); 495} 496 497/* 498 * Add privacy headers appropriate for the specified key. 499 */ 500struct ieee80211_key * 501ieee80211_crypto_encap(struct ieee80211com *ic, 502 struct ieee80211_node *ni, struct mbuf *m) 503{ 504 struct ieee80211_key *k; 505 struct ieee80211_frame *wh; 506 const struct ieee80211_cipher *cip; 507 u_int8_t keyid; 508 509 /* 510 * Multicast traffic always uses the multicast key. 511 * Otherwise if a unicast key is set we use that and 512 * it is always key index 0. When no unicast key is 513 * set we fall back to the default transmit key. 514 */ 515 wh = mtod(m, struct ieee80211_frame *); 516 if (IEEE80211_IS_MULTICAST(wh->i_addr1) || 517 ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) { 518 if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE) { 519 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 520 "[%s] no default transmit key (%s) deftxkey %u\n", 521 ether_sprintf(wh->i_addr1), __func__, 522 ic->ic_def_txkey); 523 ic->ic_stats.is_tx_nodefkey++; 524 return NULL; 525 } 526 keyid = ic->ic_def_txkey; 527 k = &ic->ic_nw_keys[ic->ic_def_txkey]; 528 } else { 529 keyid = 0; 530 k = &ni->ni_ucastkey; 531 } 532 cip = k->wk_cipher; 533 return (cip->ic_encap(k, m, keyid<<6) ? k : NULL); 534} 535 536/* 537 * Validate and strip privacy headers (and trailer) for a 538 * received frame that has the WEP/Privacy bit set. 539 */ 540struct ieee80211_key * 541ieee80211_crypto_decap(struct ieee80211com *ic, 542 struct ieee80211_node *ni, struct mbuf *m, int hdrlen) 543{ 544#define IEEE80211_WEP_HDRLEN (IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN) 545#define IEEE80211_WEP_MINLEN \ 546 (sizeof(struct ieee80211_frame) + \ 547 IEEE80211_WEP_HDRLEN + IEEE80211_WEP_CRCLEN) 548 struct ieee80211_key *k; 549 struct ieee80211_frame *wh; 550 const struct ieee80211_cipher *cip; 551 const u_int8_t *ivp; 552 u_int8_t keyid; 553 554 /* NB: this minimum size data frame could be bigger */ 555 if (m->m_pkthdr.len < IEEE80211_WEP_MINLEN) { 556 IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY, 557 "%s: WEP data frame too short, len %u\n", 558 __func__, m->m_pkthdr.len); 559 ic->ic_stats.is_rx_tooshort++; /* XXX need unique stat? */ 560 return NULL; 561 } 562 563 /* 564 * Locate the key. If unicast and there is no unicast 565 * key then we fall back to the key id in the header. 566 * This assumes unicast keys are only configured when 567 * the key id in the header is meaningless (typically 0). 568 */ 569 wh = mtod(m, struct ieee80211_frame *); 570 ivp = mtod(m, const u_int8_t *) + hdrlen; /* XXX contig */ 571 keyid = ivp[IEEE80211_WEP_IVLEN]; 572 if (IEEE80211_IS_MULTICAST(wh->i_addr1) || 573 ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) 574 k = &ic->ic_nw_keys[keyid >> 6]; 575 else 576 k = &ni->ni_ucastkey; 577 578 /* 579 * Insure crypto header is contiguous for all decap work. 580 */ 581 cip = k->wk_cipher; 582 if (m->m_len < hdrlen + cip->ic_header && 583 (m = m_pullup(m, hdrlen + cip->ic_header)) == NULL) { 584 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 585 "[%s] unable to pullup %s header\n", 586 ether_sprintf(wh->i_addr2), cip->ic_name); 587 ic->ic_stats.is_rx_wepfail++; /* XXX */ 588 return 0; 589 } 590 591 return (cip->ic_decap(k, m, hdrlen) ? k : NULL); 592#undef IEEE80211_WEP_MINLEN 593#undef IEEE80211_WEP_HDRLEN 594} 595