Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/net80211/ieee80211_crypto.c
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1 /* $NetBSD: ieee80211_crypto.c,v 1.23 2018/05/08 07:02:07 maxv Exp $ */ 2 3 /* 4 * Copyright (c) 2001 Atsushi Onoe 5 * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission. 18 * 19 * Alternatively, this software may be distributed under the terms of the 20 * GNU General Public License ("GPL") version 2 as published by the Free 21 * Software Foundation. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #ifdef __FreeBSD__ 37 __FBSDID("$FreeBSD: src/sys/net80211/ieee80211_crypto.c,v 1.12 2005/08/08 18:46:35 sam Exp $"); 38 #endif 39 #ifdef __NetBSD__ 40 __KERNEL_RCSID(0, "$NetBSD: ieee80211_crypto.c,v 1.23 2018/05/08 07:02:07 maxv Exp $"); 41 #endif 42 43 #ifdef _KERNEL_OPT 44 #include "opt_inet.h" 45 #endif 46 47 /* 48 * IEEE 802.11 generic crypto support. 49 */ 50 #include <sys/param.h> 51 #include <sys/mbuf.h> 52 53 #include <sys/socket.h> 54 #include <sys/sockio.h> 55 #include <sys/endian.h> 56 #include <sys/errno.h> 57 #include <sys/proc.h> 58 #include <sys/sysctl.h> 59 60 #include <net/if.h> 61 #include <net/if_media.h> 62 #include <net/if_arp.h> 63 #include <net/if_ether.h> 64 #include <net/if_llc.h> 65 66 #include <net80211/ieee80211_netbsd.h> 67 #include <net80211/ieee80211_var.h> 68 69 /* 70 * Table of registered cipher modules. 71 */ 72 static const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX]; 73 74 #ifdef INET 75 #include <netinet/in.h> 76 #include <net/if_ether.h> 77 #endif 78 79 static int _ieee80211_crypto_delkey(struct ieee80211com *, 80 struct ieee80211_key *); 81 82 /* 83 * Default "null" key management routines. 84 */ 85 static int 86 null_key_alloc(struct ieee80211com *ic, const struct ieee80211_key *k, 87 ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix) 88 { 89 if (!(&ic->ic_nw_keys[0] <= k && 90 k < &ic->ic_nw_keys[IEEE80211_WEP_NKID])) { 91 /* 92 * Not in the global key table, the driver should handle this 93 * by allocating a slot in the h/w key table/cache. In 94 * lieu of that return key slot 0 for any unicast key 95 * request. We disallow the request if this is a group key. 96 * This default policy does the right thing for legacy hardware 97 * with a 4 key table. It also handles devices that pass 98 * packets through untouched when marked with the WEP bit 99 * and key index 0. 100 */ 101 if (k->wk_flags & IEEE80211_KEY_GROUP) 102 return 0; 103 *keyix = 0; /* NB: use key index 0 for ucast key */ 104 } else { 105 *keyix = k - ic->ic_nw_keys; 106 } 107 *rxkeyix = IEEE80211_KEYIX_NONE; /* XXX maybe *keyix? */ 108 return 1; 109 } 110 111 static int 112 null_key_delete(struct ieee80211com *ic, const struct ieee80211_key *k) 113 { 114 return 1; 115 } 116 117 static int 118 null_key_set(struct ieee80211com *ic, const struct ieee80211_key *k, 119 const u_int8_t mac[IEEE80211_ADDR_LEN]) 120 { 121 return 1; 122 } 123 124 static void 125 null_key_update(struct ieee80211com *ic) 126 { 127 ; 128 } 129 130 /* 131 * Write-arounds for common operations. 132 */ 133 static __inline void 134 cipher_detach(struct ieee80211_key *key) 135 { 136 key->wk_cipher->ic_detach(key); 137 } 138 139 /* 140 * Wrappers for driver key management methods. 141 */ 142 static __inline int 143 dev_key_alloc(struct ieee80211com *ic, const struct ieee80211_key *key, 144 ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix) 145 { 146 return ic->ic_crypto.cs_key_alloc(ic, key, keyix, rxkeyix); 147 } 148 149 static __inline int 150 dev_key_delete(struct ieee80211com *ic, const struct ieee80211_key *key) 151 { 152 return ic->ic_crypto.cs_key_delete(ic, key); 153 } 154 155 static __inline int 156 dev_key_set(struct ieee80211com *ic, const struct ieee80211_key *key, 157 const u_int8_t mac[IEEE80211_ADDR_LEN]) 158 { 159 return ic->ic_crypto.cs_key_set(ic, key, mac); 160 } 161 162 /* 163 * Setup crypto support. 164 */ 165 void 166 ieee80211_crypto_attach(struct ieee80211com *ic) 167 { 168 struct ieee80211_crypto_state *cs = &ic->ic_crypto; 169 int i; 170 171 /* NB: we assume everything is pre-zero'd */ 172 cs->cs_def_txkey = IEEE80211_KEYIX_NONE; 173 cs->cs_max_keyix = IEEE80211_WEP_NKID; 174 ciphers[IEEE80211_CIPHER_NONE] = &ieee80211_cipher_none; 175 for (i = 0; i < IEEE80211_WEP_NKID; i++) 176 ieee80211_crypto_resetkey(ic, &cs->cs_nw_keys[i], 177 IEEE80211_KEYIX_NONE); 178 /* 179 * Initialize the driver key support routines to noop entries. 180 * This is useful especially for the cipher test modules. 181 */ 182 cs->cs_key_alloc = null_key_alloc; 183 cs->cs_key_set = null_key_set; 184 cs->cs_key_delete = null_key_delete; 185 cs->cs_key_update_begin = null_key_update; 186 cs->cs_key_update_end = null_key_update; 187 } 188 189 /* 190 * Teardown crypto support. 191 */ 192 void 193 ieee80211_crypto_detach(struct ieee80211com *ic) 194 { 195 ieee80211_crypto_delglobalkeys(ic); 196 } 197 198 /* 199 * Register a crypto cipher module. 200 */ 201 void 202 ieee80211_crypto_register(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 ciphers[cip->ic_cipher] = cip; 215 } 216 217 /* 218 * Unregister a crypto cipher module. 219 */ 220 void 221 ieee80211_crypto_unregister(const struct ieee80211_cipher *cip) 222 { 223 if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) { 224 printf("%s: cipher %s has an invalid cipher index %u\n", 225 __func__, cip->ic_name, cip->ic_cipher); 226 return; 227 } 228 if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) { 229 printf("%s: cipher %s registered with a different template\n", 230 __func__, cip->ic_name); 231 return; 232 } 233 /* NB: don't complain about not being registered */ 234 /* XXX disallow if references */ 235 ciphers[cip->ic_cipher] = NULL; 236 } 237 238 int 239 ieee80211_crypto_available(u_int cipher) 240 { 241 return cipher < IEEE80211_CIPHER_MAX && ciphers[cipher] != NULL; 242 } 243 244 /* XXX well-known names! */ 245 static const char *cipher_modnames[] = { 246 "wlan_wep", /* IEEE80211_CIPHER_WEP */ 247 "wlan_tkip", /* IEEE80211_CIPHER_TKIP */ 248 "wlan_aes_ocb", /* IEEE80211_CIPHER_AES_OCB */ 249 "wlan_ccmp", /* IEEE80211_CIPHER_AES_CCM */ 250 "wlan_ckip", /* IEEE80211_CIPHER_CKIP */ 251 }; 252 253 /* 254 * Establish a relationship between the specified key and cipher 255 * and, if necessary, allocate a hardware index from the driver. 256 * Note that when a fixed key index is required it must be specified 257 * and we blindly assign it w/o consulting the driver (XXX). 258 * 259 * This must be the first call applied to a key; all the other key 260 * routines assume wk_cipher is setup. 261 * 262 * Locking must be handled by the caller using: 263 * ieee80211_key_update_begin(ic); 264 * ieee80211_key_update_end(ic); 265 */ 266 int 267 ieee80211_crypto_newkey(struct ieee80211com *ic, int cipher, int flags, 268 struct ieee80211_key *key) 269 { 270 #define N(a) (sizeof(a) / sizeof(a[0])) 271 const struct ieee80211_cipher *cip; 272 ieee80211_keyix keyix, rxkeyix; 273 void *keyctx; 274 int oflags; 275 276 /* 277 * Validate cipher and set reference to cipher routines. 278 */ 279 if (cipher >= IEEE80211_CIPHER_MAX) { 280 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 281 "%s: invalid cipher %u\n", __func__, cipher); 282 ic->ic_stats.is_crypto_badcipher++; 283 return 0; 284 } 285 cip = ciphers[cipher]; 286 287 if (cip == NULL) { 288 /* 289 * Auto-load cipher module if we have a well-known name 290 * for it. It might be better to use string names rather 291 * than numbers and craft a module name based on the cipher 292 * name; e.g. wlan_cipher_<cipher-name>. 293 */ 294 if (cipher < N(cipher_modnames)) { 295 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 296 "%s: unregistered cipher %u, load module %s\n", 297 __func__, cipher, cipher_modnames[cipher]); 298 ieee80211_load_module(cipher_modnames[cipher]); 299 /* 300 * If cipher module loaded it should immediately 301 * call ieee80211_crypto_register which will fill 302 * in the entry in the ciphers array. 303 */ 304 cip = ciphers[cipher]; 305 } 306 if (cip == NULL) { 307 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 308 "%s: unable to load cipher %u, module %s\n", 309 __func__, cipher, 310 cipher < N(cipher_modnames) ? 311 cipher_modnames[cipher] : "<unknown>"); 312 ic->ic_stats.is_crypto_nocipher++; 313 return 0; 314 } 315 } 316 317 oflags = key->wk_flags; 318 flags &= IEEE80211_KEY_COMMON; 319 320 /* 321 * If the hardware does not support the cipher then 322 * fall back to a host-based implementation. 323 */ 324 if ((ic->ic_caps & (1<<cipher)) == 0) { 325 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 326 "%s: no h/w support for cipher %s, falling back to s/w\n", 327 __func__, cip->ic_name); 328 flags |= IEEE80211_KEY_SWCRYPT; 329 } 330 331 /* 332 * Hardware TKIP with software MIC is an important 333 * combination; we handle it by flagging each key, 334 * the cipher modules honor it. 335 */ 336 if (cipher == IEEE80211_CIPHER_TKIP && 337 (ic->ic_caps & IEEE80211_C_TKIPMIC) == 0) { 338 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 339 "%s: no h/w support for TKIP MIC, falling back to s/w\n", 340 __func__); 341 flags |= IEEE80211_KEY_SWMIC; 342 } 343 344 /* 345 * Bind cipher to key instance. Note we do this 346 * after checking the device capabilities so the 347 * cipher module can optimize space usage based on 348 * whether or not it needs to do the cipher work. 349 */ 350 if (key->wk_cipher != cip || key->wk_flags != flags) { 351 again: 352 /* 353 * Fillin the flags so cipher modules can see s/w 354 * crypto requirements and potentially allocate 355 * different state and/or attach different method 356 * pointers. 357 * 358 * XXX this is not right when s/w crypto fallback 359 * fails and we try to restore previous state. 360 */ 361 key->wk_flags = flags; 362 keyctx = cip->ic_attach(ic, key); 363 if (keyctx == NULL) { 364 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 365 "%s: unable to attach cipher %s\n", 366 __func__, cip->ic_name); 367 key->wk_flags = oflags; /* restore old flags */ 368 ic->ic_stats.is_crypto_attachfail++; 369 return 0; 370 } 371 cipher_detach(key); 372 key->wk_cipher = cip; /* XXX refcnt? */ 373 key->wk_private = keyctx; 374 } 375 /* 376 * Commit to requested usage so driver can see the flags. 377 */ 378 key->wk_flags = flags; 379 380 /* 381 * Ask the driver for a key index if we don't have one. 382 * Note that entries in the global key table always have 383 * an index; this means it's safe to call this routine 384 * for these entries just to setup the reference to the 385 * cipher template. Note also that when using software 386 * crypto we also call the driver to give us a key index. 387 */ 388 if (key->wk_keyix == IEEE80211_KEYIX_NONE) { 389 if (!dev_key_alloc(ic, key, &keyix, &rxkeyix)) { 390 /* 391 * Driver has no room; fallback to doing crypto 392 * in the host. We change the flags and start the 393 * procedure over. If we get back here then there's 394 * no hope and we bail. Note that this can leave 395 * the key in a inconsistent state if the caller 396 * continues to use it. 397 */ 398 if ((key->wk_flags & IEEE80211_KEY_SWCRYPT) == 0) { 399 ic->ic_stats.is_crypto_swfallback++; 400 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 401 "%s: no h/w resources for cipher %s, " 402 "falling back to s/w\n", __func__, 403 cip->ic_name); 404 oflags = key->wk_flags; 405 flags |= IEEE80211_KEY_SWCRYPT; 406 if (cipher == IEEE80211_CIPHER_TKIP) 407 flags |= IEEE80211_KEY_SWMIC; 408 goto again; 409 } 410 ic->ic_stats.is_crypto_keyfail++; 411 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 412 "%s: unable to setup cipher %s\n", 413 __func__, cip->ic_name); 414 return 0; 415 } 416 key->wk_keyix = keyix; 417 key->wk_rxkeyix = rxkeyix; 418 } 419 return 1; 420 #undef N 421 } 422 423 /* 424 * Remove the key (no locking, for internal use). 425 */ 426 static int 427 _ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key) 428 { 429 ieee80211_keyix keyix; 430 431 IASSERT(key->wk_cipher != NULL, ("No cipher!")); 432 433 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 434 "%s: %s keyix %u flags 0x%x rsc %ju tsc %ju len %u\n", 435 __func__, key->wk_cipher->ic_name, 436 key->wk_keyix, key->wk_flags, 437 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen); 438 439 keyix = key->wk_keyix; 440 if (keyix != IEEE80211_KEYIX_NONE) { 441 /* 442 * Remove hardware entry. 443 */ 444 /* XXX key cache */ 445 if (!dev_key_delete(ic, key)) { 446 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 447 "%s: driver did not delete key index %u\n", 448 __func__, keyix); 449 ic->ic_stats.is_crypto_delkey++; 450 /* XXX recovery? */ 451 } 452 } 453 cipher_detach(key); 454 memset(key, 0, sizeof(*key)); 455 ieee80211_crypto_resetkey(ic, key, IEEE80211_KEYIX_NONE); 456 return 1; 457 } 458 459 /* 460 * Remove the specified key. 461 */ 462 int 463 ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key) 464 { 465 int status; 466 467 ieee80211_key_update_begin(ic); 468 status = _ieee80211_crypto_delkey(ic, key); 469 ieee80211_key_update_end(ic); 470 return status; 471 } 472 473 /* 474 * Clear the global key table. 475 */ 476 void 477 ieee80211_crypto_delglobalkeys(struct ieee80211com *ic) 478 { 479 int i; 480 481 ieee80211_key_update_begin(ic); 482 for (i = 0; i < IEEE80211_WEP_NKID; i++) 483 (void)_ieee80211_crypto_delkey(ic, &ic->ic_nw_keys[i]); 484 ieee80211_key_update_end(ic); 485 } 486 487 /* 488 * Set the contents of the specified key. 489 * 490 * Locking must be handled by the caller using: 491 * ieee80211_key_update_begin(ic); 492 * ieee80211_key_update_end(ic); 493 */ 494 int 495 ieee80211_crypto_setkey(struct ieee80211com *ic, struct ieee80211_key *key, 496 const u_int8_t macaddr[IEEE80211_ADDR_LEN]) 497 { 498 const struct ieee80211_cipher *cip = key->wk_cipher; 499 500 IASSERT(cip != NULL, ("No cipher!")); 501 502 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 503 "%s: %s keyix %u flags 0x%x mac %s rsc %ju tsc %ju len %u\n", 504 __func__, cip->ic_name, key->wk_keyix, 505 key->wk_flags, ether_sprintf(macaddr), 506 key->wk_keyrsc, key->wk_keytsc, key->wk_keylen); 507 508 /* 509 * Give cipher a chance to validate key contents. 510 * XXX should happen before modifying state. 511 */ 512 if (!cip->ic_setkey(key)) { 513 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 514 "%s: cipher %s rejected key index %u len %u flags 0x%x\n", 515 __func__, cip->ic_name, key->wk_keyix, 516 key->wk_keylen, key->wk_flags); 517 ic->ic_stats.is_crypto_setkey_cipher++; 518 return 0; 519 } 520 if (key->wk_keyix == IEEE80211_KEYIX_NONE) { 521 /* XXX nothing allocated, should not happen */ 522 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 523 "%s: no key index; should not happen!\n", __func__); 524 ic->ic_stats.is_crypto_setkey_nokey++; 525 return 0; 526 } 527 return dev_key_set(ic, key, macaddr); 528 } 529 530 /* 531 * Add privacy headers appropriate for the specified key. 532 * 533 * XXX XXX XXX: Here we modify 'm', and potentially reallocate it. We 534 * should pass back to the caller the updated pointer to avoid 535 * use-after-frees. This can be done by changing the argument to be **m, 536 * but many drivers will have to be changed accordingly. 537 */ 538 struct ieee80211_key * 539 ieee80211_crypto_encap(struct ieee80211com *ic, struct ieee80211_node *ni, 540 struct mbuf *m) 541 { 542 struct ieee80211_key *k; 543 struct ieee80211_frame *wh; 544 const struct ieee80211_cipher *cip; 545 u_int8_t keyid, *hdr; 546 int hdrlen; 547 548 /* 549 * Multicast traffic always uses the multicast key. 550 * Otherwise if a unicast key is set we use that and 551 * it is always key index 0. When no unicast key is 552 * set we fall back to the default transmit key. 553 */ 554 wh = mtod(m, struct ieee80211_frame *); 555 if (IEEE80211_IS_MULTICAST(wh->i_addr1) || 556 ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) { 557 if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE) { 558 IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, 559 "[%s] no default transmit key (%s) deftxkey %u\n", 560 ether_sprintf(wh->i_addr1), __func__, 561 ic->ic_def_txkey); 562 ic->ic_stats.is_tx_nodefkey++; 563 return NULL; 564 } 565 keyid = ic->ic_def_txkey; 566 k = &ic->ic_nw_keys[ic->ic_def_txkey]; 567 } else { 568 keyid = 0; 569 k = &ni->ni_ucastkey; 570 } 571 cip = k->wk_cipher; 572 573 /* 574 * The crypto header is added after the IEEE802.11 header. Prepend 575 * the size of the crypto header, and move the IEEE802.11 header back 576 * to the beginning of the mbuf. Ensure everything is contiguous. 577 */ 578 hdrlen = ieee80211_hdrspace(ic, mtod(m, void *)); 579 M_PREPEND(m, cip->ic_header, M_NOWAIT); 580 if (m && m->m_len < hdrlen + cip->ic_header) { 581 m = m_pullup(m, hdrlen + cip->ic_header); 582 } 583 if (m == NULL) { 584 return NULL; 585 } 586 hdr = mtod(m, u_int8_t *); 587 memmove(hdr, hdr + cip->ic_header, hdrlen); 588 589 return (cip->ic_encap(k, m, keyid<<6) ? k : NULL); 590 } 591 592 #define IEEE80211_WEP_HDRLEN (IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN) 593 #define IEEE80211_WEP_MINLEN \ 594 (sizeof(struct ieee80211_frame) + \ 595 IEEE80211_WEP_HDRLEN + IEEE80211_WEP_CRCLEN) 596 597 /* 598 * Validate and strip privacy headers (and trailer) for a 599 * received frame that has the WEP/Privacy bit set. 600 */ 601 struct ieee80211_key * 602 ieee80211_crypto_decap(struct ieee80211com *ic, 603 struct ieee80211_node *ni, struct mbuf **mp, int hdrlen) 604 { 605 const struct ieee80211_cipher *cip; 606 struct ieee80211_key *k; 607 struct ieee80211_frame *wh; 608 struct mbuf *m = *mp; 609 u_int8_t keyid; 610 611 KASSERT((m->m_flags & M_PKTHDR) != 0); 612 613 /* 614 * This minimum size data frame could be bigger. It is re-checked 615 * below. 616 */ 617 if (m->m_pkthdr.len < IEEE80211_WEP_MINLEN) { 618 IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY, 619 "%s: WEP data frame too short, len %u\n", 620 __func__, m->m_pkthdr.len); 621 ic->ic_stats.is_rx_tooshort++; 622 return NULL; 623 } 624 625 /* 626 * Locate the key. If unicast and there is no unicast 627 * key then we fall back to the key id in the header. 628 * This assumes unicast keys are only configured when 629 * the key id in the header is meaningless (typically 0). 630 */ 631 wh = mtod(m, struct ieee80211_frame *); 632 m_copydata(m, hdrlen + IEEE80211_WEP_IVLEN, sizeof(keyid), &keyid); 633 if (IEEE80211_IS_MULTICAST(wh->i_addr1) || 634 ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) { 635 k = &ic->ic_nw_keys[keyid >> 6]; 636 } else { 637 k = &ni->ni_ucastkey; 638 } 639 640 /* 641 * Insure crypto header is contiguous for all decap work. 642 */ 643 cip = k->wk_cipher; 644 if (m->m_len < hdrlen + cip->ic_header) { 645 m = m_pullup(m, hdrlen + cip->ic_header); 646 *mp = m; 647 } 648 649 if (m == NULL) { 650 ic->ic_stats.is_rx_tooshort++; 651 return NULL; 652 } 653 654 /* 655 * Ensure there is a header+trailer included. 656 */ 657 if (m->m_pkthdr.len < hdrlen + cip->ic_header + cip->ic_trailer) { 658 IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY, 659 "%s: WEP data frame too short, len %u\n", 660 __func__, m->m_pkthdr.len); 661 ic->ic_stats.is_rx_tooshort++; 662 return NULL; 663 } 664 665 return (cip->ic_decap(k, m, hdrlen) ? k : NULL); 666 }
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