1 /*- 2 * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * Alternatively, this software may be distributed under the terms of the 17 * GNU General Public License ("GPL") version 2 as published by the Free 18 * Software Foundation. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #ifdef __FreeBSD__ 34 __FBSDID("$FreeBSD: src/sys/net80211/ieee80211_crypto_ccmp.c,v 1.4 2004/12/31 22:42:38 sam Exp $"); 35 #endif 36 #ifdef __NetBSD__ 37 __KERNEL_RCSID(0, "$NetBSD: ieee80211_crypto_ccmp.c,v 1.2 2005/06/22 06:16:02 dyoung Exp $"); 38 #endif 39 40 /* 41 * IEEE 802.11i AES-CCMP crypto support. 42 * 43 * Part of this module is derived from similar code in the Host 44 * AP driver. The code is used with the consent of the author and 45 * it's license is included below. 46 */ 47 #include <sys/param.h> 48 #include <sys/systm.h> 49 #include <sys/mbuf.h> 50 #include <sys/malloc.h> 51 #include <sys/kernel.h> 52 53 #include <sys/socket.h> 54 55 #include <net/if.h> 56 #include <net/if_media.h> 57 58 #include <net80211/ieee80211_var.h> 59 60 #include <crypto/rijndael/rijndael.h> 61 62 #define AES_BLOCK_LEN 16 63 64 struct ccmp_ctx { 65 struct ieee80211com *cc_ic; /* for diagnostics */ 66 rijndael_ctx cc_aes; 67 }; 68 69 static void *ccmp_attach(struct ieee80211com *, struct ieee80211_key *); 70 static void ccmp_detach(struct ieee80211_key *); 71 static int ccmp_setkey(struct ieee80211_key *); 72 static int ccmp_encap(struct ieee80211_key *k, struct mbuf *, u_int8_t keyid); 73 static int ccmp_decap(struct ieee80211_key *, struct mbuf *); 74 static int ccmp_enmic(struct ieee80211_key *, struct mbuf *); 75 static int ccmp_demic(struct ieee80211_key *, struct mbuf *); 76 77 const struct ieee80211_cipher ieee80211_cipher_ccmp = { 78 .ic_name = "AES-CCM", 79 .ic_cipher = IEEE80211_CIPHER_AES_CCM, 80 .ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN + 81 IEEE80211_WEP_EXTIVLEN, 82 .ic_trailer = IEEE80211_WEP_MICLEN, 83 .ic_miclen = 0, 84 .ic_attach = ccmp_attach, 85 .ic_detach = ccmp_detach, 86 .ic_setkey = ccmp_setkey, 87 .ic_encap = ccmp_encap, 88 .ic_decap = ccmp_decap, 89 .ic_enmic = ccmp_enmic, 90 .ic_demic = ccmp_demic, 91 }; 92 93 #define ccmp ieee80211_cipher_ccmp 94 95 static int ccmp_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen); 96 static int ccmp_decrypt(struct ieee80211_key *, u_int64_t pn, 97 struct mbuf *, int hdrlen); 98 99 static void * 100 ccmp_attach(struct ieee80211com *ic, struct ieee80211_key *k) 101 { 102 struct ccmp_ctx *ctx; 103 104 MALLOC(ctx, struct ccmp_ctx *, sizeof(struct ccmp_ctx), 105 M_DEVBUF, M_NOWAIT | M_ZERO); 106 if (ctx == NULL) { 107 ic->ic_stats.is_crypto_nomem++; 108 return NULL; 109 } 110 ctx->cc_ic = ic; 111 return ctx; 112 } 113 114 static void 115 ccmp_detach(struct ieee80211_key *k) 116 { 117 struct ccmp_ctx *ctx = k->wk_private; 118 119 FREE(ctx, M_DEVBUF); 120 } 121 122 static int 123 ccmp_setkey(struct ieee80211_key *k) 124 { 125 struct ccmp_ctx *ctx = k->wk_private; 126 127 if (k->wk_keylen != (128/NBBY)) { 128 IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO, 129 "%s: Invalid key length %u, expecting %u\n", 130 __func__, k->wk_keylen, 128/NBBY); 131 return 0; 132 } 133 if (k->wk_flags & IEEE80211_KEY_SWCRYPT) 134 rijndael_set_key(&ctx->cc_aes, k->wk_key, k->wk_keylen*NBBY); 135 return 1; 136 } 137 138 /* 139 * Add privacy headers appropriate for the specified key. 140 */ 141 static int 142 ccmp_encap(struct ieee80211_key *k, struct mbuf *m, u_int8_t keyid) 143 { 144 struct ccmp_ctx *ctx = k->wk_private; 145 struct ieee80211com *ic = ctx->cc_ic; 146 u_int8_t *ivp; 147 int hdrlen; 148 149 hdrlen = ieee80211_hdrspace(ic, mtod(m, void *)); 150 151 /* 152 * Copy down 802.11 header and add the IV, KeyID, and ExtIV. 153 */ 154 M_PREPEND(m, ccmp.ic_header, M_NOWAIT); 155 if (m == NULL) 156 return 0; 157 ivp = mtod(m, u_int8_t *); 158 ovbcopy(ivp + ccmp.ic_header, ivp, hdrlen); 159 ivp += hdrlen; 160 161 k->wk_keytsc++; /* XXX wrap at 48 bits */ 162 ivp[0] = k->wk_keytsc >> 0; /* PN0 */ 163 ivp[1] = k->wk_keytsc >> 8; /* PN1 */ 164 ivp[2] = 0; /* Reserved */ 165 ivp[3] = keyid | IEEE80211_WEP_EXTIV; /* KeyID | ExtID */ 166 ivp[4] = k->wk_keytsc >> 16; /* PN2 */ 167 ivp[5] = k->wk_keytsc >> 24; /* PN3 */ 168 ivp[6] = k->wk_keytsc >> 32; /* PN4 */ 169 ivp[7] = k->wk_keytsc >> 40; /* PN5 */ 170 171 /* 172 * Finally, do software encrypt if neeed. 173 */ 174 if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) && 175 !ccmp_encrypt(k, m, hdrlen)) 176 return 0; 177 178 return 1; 179 } 180 181 /* 182 * Add MIC to the frame as needed. 183 */ 184 static int 185 ccmp_enmic(struct ieee80211_key *k, struct mbuf *m) 186 { 187 188 return 1; 189 } 190 191 static __inline uint64_t 192 READ_6(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3, uint8_t b4, uint8_t b5) 193 { 194 uint32_t iv32 = (b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24); 195 uint16_t iv16 = (b4 << 0) | (b5 << 8); 196 return (((uint64_t)iv16) << 32) | iv32; 197 } 198 199 /* 200 * Validate and strip privacy headers (and trailer) for a 201 * received frame. The specified key should be correct but 202 * is also verified. 203 */ 204 static int 205 ccmp_decap(struct ieee80211_key *k, struct mbuf *m) 206 { 207 struct ccmp_ctx *ctx = k->wk_private; 208 struct ieee80211_frame *wh; 209 uint8_t *ivp; 210 uint64_t pn; 211 int hdrlen; 212 213 /* 214 * Header should have extended IV and sequence number; 215 * verify the former and validate the latter. 216 */ 217 wh = mtod(m, struct ieee80211_frame *); 218 hdrlen = ieee80211_hdrsize(wh); 219 ivp = mtod(m, uint8_t *) + hdrlen; 220 if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) { 221 /* 222 * No extended IV; discard frame. 223 */ 224 IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO, 225 "[%s] Missing ExtIV for AES-CCM cipher\n", 226 ether_sprintf(wh->i_addr2)); 227 ctx->cc_ic->ic_stats.is_rx_ccmpformat++; 228 return 0; 229 } 230 pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]); 231 if (pn <= k->wk_keyrsc) { 232 /* 233 * Replay violation. 234 */ 235 ieee80211_notify_replay_failure(ctx->cc_ic, wh, k, pn); 236 ctx->cc_ic->ic_stats.is_rx_ccmpreplay++; 237 return 0; 238 } 239 240 /* 241 * Check if the device handled the decrypt in hardware. 242 * If so we just strip the header; otherwise we need to 243 * handle the decrypt in software. Note that for the 244 * latter we leave the header in place for use in the 245 * decryption work. 246 */ 247 if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) && 248 !ccmp_decrypt(k, pn, m, hdrlen)) 249 return 0; 250 251 /* 252 * Copy up 802.11 header and strip crypto bits. 253 */ 254 ovbcopy(mtod(m, void *), mtod(m, u_int8_t *) + ccmp.ic_header, hdrlen); 255 m_adj(m, ccmp.ic_header); 256 m_adj(m, -ccmp.ic_trailer); 257 258 /* 259 * Ok to update rsc now. 260 */ 261 k->wk_keyrsc = pn; 262 263 return 1; 264 } 265 266 /* 267 * Verify and strip MIC from the frame. 268 */ 269 static int 270 ccmp_demic(struct ieee80211_key *k, struct mbuf *m) 271 { 272 return 1; 273 } 274 275 static __inline void 276 xor_block(uint8_t *b, const uint8_t *a, size_t len) 277 { 278 int i; 279 for (i = 0; i < len; i++) 280 b[i] ^= a[i]; 281 } 282 283 /* 284 * Host AP crypt: host-based CCMP encryption implementation for Host AP driver 285 * 286 * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi> 287 * 288 * This program is free software; you can redistribute it and/or modify 289 * it under the terms of the GNU General Public License version 2 as 290 * published by the Free Software Foundation. See README and COPYING for 291 * more details. 292 * 293 * Alternatively, this software may be distributed under the terms of BSD 294 * license. 295 */ 296 297 static void 298 ccmp_init_blocks(rijndael_ctx *ctx, struct ieee80211_frame *wh, 299 u_int64_t pn, size_t dlen, 300 uint8_t b0[AES_BLOCK_LEN], uint8_t aad[2 * AES_BLOCK_LEN], 301 uint8_t auth[AES_BLOCK_LEN], uint8_t s0[AES_BLOCK_LEN]) 302 { 303 #define IS_4ADDRESS(wh) \ 304 ((wh->i_fc[1] & IEEE80211_FC1_DIR_MASK) == IEEE80211_FC1_DIR_DSTODS) 305 #define IS_QOS_DATA(wh) IEEE80211_QOS_HAS_SEQ(wh) 306 307 /* CCM Initial Block: 308 * Flag (Include authentication header, M=3 (8-octet MIC), 309 * L=1 (2-octet Dlen)) 310 * Nonce: 0x00 | A2 | PN 311 * Dlen */ 312 b0[0] = 0x59; 313 /* NB: b0[1] set below */ 314 IEEE80211_ADDR_COPY(b0 + 2, wh->i_addr2); 315 b0[8] = pn >> 40; 316 b0[9] = pn >> 32; 317 b0[10] = pn >> 24; 318 b0[11] = pn >> 16; 319 b0[12] = pn >> 8; 320 b0[13] = pn >> 0; 321 b0[14] = (dlen >> 8) & 0xff; 322 b0[15] = dlen & 0xff; 323 324 /* AAD: 325 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one 326 * A1 | A2 | A3 327 * SC with bits 4..15 (seq#) masked to zero 328 * A4 (if present) 329 * QC (if present) 330 */ 331 aad[0] = 0; /* AAD length >> 8 */ 332 /* NB: aad[1] set below */ 333 aad[2] = wh->i_fc[0] & 0x8f; /* XXX magic #s */ 334 aad[3] = wh->i_fc[1] & 0xc7; /* XXX magic #s */ 335 /* NB: we know 3 addresses are contiguous */ 336 memcpy(aad + 4, wh->i_addr1, 3 * IEEE80211_ADDR_LEN); 337 aad[22] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK; 338 aad[23] = 0; /* all bits masked */ 339 /* 340 * Construct variable-length portion of AAD based 341 * on whether this is a 4-address frame/QOS frame. 342 * We always zero-pad to 32 bytes before running it 343 * through the cipher. 344 * 345 * We also fill in the priority bits of the CCM 346 * initial block as we know whether or not we have 347 * a QOS frame. 348 */ 349 if (IS_4ADDRESS(wh)) { 350 IEEE80211_ADDR_COPY(aad + 24, 351 ((struct ieee80211_frame_addr4 *)wh)->i_addr4); 352 if (IS_QOS_DATA(wh)) { 353 struct ieee80211_qosframe_addr4 *qwh4 = 354 (struct ieee80211_qosframe_addr4 *) wh; 355 aad[30] = qwh4->i_qos[0] & 0x0f;/* just priority bits */ 356 aad[31] = 0; 357 b0[1] = aad[30]; 358 aad[1] = 22 + IEEE80211_ADDR_LEN + 2; 359 } else { 360 *(u_int16_t *)&aad[30] = 0; 361 b0[1] = 0; 362 aad[1] = 22 + IEEE80211_ADDR_LEN; 363 } 364 } else { 365 if (IS_QOS_DATA(wh)) { 366 struct ieee80211_qosframe *qwh = 367 (struct ieee80211_qosframe*) wh; 368 aad[24] = qwh->i_qos[0] & 0x0f; /* just priority bits */ 369 aad[25] = 0; 370 b0[1] = aad[24]; 371 aad[1] = 22 + 2; 372 } else { 373 *(u_int16_t *)&aad[24] = 0; 374 b0[1] = 0; 375 aad[1] = 22; 376 } 377 *(u_int16_t *)&aad[26] = 0; 378 *(u_int32_t *)&aad[28] = 0; 379 } 380 381 /* Start with the first block and AAD */ 382 rijndael_encrypt(ctx, b0, auth); 383 xor_block(auth, aad, AES_BLOCK_LEN); 384 rijndael_encrypt(ctx, auth, auth); 385 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN); 386 rijndael_encrypt(ctx, auth, auth); 387 b0[0] &= 0x07; 388 b0[14] = b0[15] = 0; 389 rijndael_encrypt(ctx, b0, s0); 390 #undef IS_QOS_DATA 391 #undef IS_4ADDRESS 392 } 393 394 #define CCMP_ENCRYPT(_i, _b, _b0, _pos, _e, _len) do { \ 395 /* Authentication */ \ 396 xor_block(_b, _pos, _len); \ 397 rijndael_encrypt(&ctx->cc_aes, _b, _b); \ 398 /* Encryption, with counter */ \ 399 _b0[14] = (_i >> 8) & 0xff; \ 400 _b0[15] = _i & 0xff; \ 401 rijndael_encrypt(&ctx->cc_aes, _b0, _e); \ 402 xor_block(_pos, _e, _len); \ 403 } while (0) 404 405 static int 406 ccmp_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen) 407 { 408 struct ccmp_ctx *ctx = key->wk_private; 409 struct ieee80211_frame *wh; 410 struct mbuf *m = m0; 411 int data_len, i; 412 uint8_t aad[2 * AES_BLOCK_LEN], b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN], 413 e[AES_BLOCK_LEN], s0[AES_BLOCK_LEN]; 414 uint8_t *pos; 415 u_int space; 416 417 ctx->cc_ic->ic_stats.is_crypto_ccmp++; 418 419 wh = mtod(m, struct ieee80211_frame *); 420 data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header); 421 ccmp_init_blocks(&ctx->cc_aes, wh, key->wk_keytsc, 422 data_len, b0, aad, b, s0); 423 424 i = 1; 425 pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header; 426 /* NB: assumes header is entirely in first mbuf */ 427 space = m->m_len - (hdrlen + ccmp.ic_header); 428 for (;;) { 429 if (space > data_len) 430 space = data_len; 431 /* 432 * Do full blocks. 433 */ 434 while (space >= AES_BLOCK_LEN) { 435 CCMP_ENCRYPT(i, b, b0, pos, e, AES_BLOCK_LEN); 436 pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN; 437 data_len -= AES_BLOCK_LEN; 438 i++; 439 } 440 if (data_len <= 0) /* no more data */ 441 break; 442 m = m->m_next; 443 if (m == NULL) { /* last buffer */ 444 if (space != 0) { 445 /* 446 * Short last block. 447 */ 448 CCMP_ENCRYPT(i, b, b0, pos, e, space); 449 } 450 break; 451 } 452 if (space != 0) { 453 uint8_t *pos_next; 454 u_int space_next; 455 u_int len; 456 457 /* 458 * Block straddles buffers, split references. We 459 * do not handle splits that require >2 buffers. 460 */ 461 pos_next = mtod(m, uint8_t *); 462 len = min(data_len, AES_BLOCK_LEN); 463 space_next = len > space ? len - space : 0; 464 IASSERT(m->m_len >= space_next, 465 ("not enough data in following buffer, " 466 "m_len %u need %u\n", m->m_len, space_next)); 467 468 xor_block(b+space, pos_next, space_next); 469 CCMP_ENCRYPT(i, b, b0, pos, e, space); 470 xor_block(pos_next, e+space, space_next); 471 data_len -= len; 472 /* XXX could check for data_len <= 0 */ 473 i++; 474 475 pos = pos_next + space_next; 476 space = m->m_len - space_next; 477 } else { 478 /* 479 * Setup for next buffer. 480 */ 481 pos = mtod(m, uint8_t *); 482 space = m->m_len; 483 } 484 } 485 /* tack on MIC */ 486 xor_block(b, s0, ccmp.ic_trailer); 487 return m_append(m0, ccmp.ic_trailer, b); 488 } 489 #undef CCMP_ENCRYPT 490 491 #define CCMP_DECRYPT(_i, _b, _b0, _pos, _a, _len) do { \ 492 /* Decrypt, with counter */ \ 493 _b0[14] = (_i >> 8) & 0xff; \ 494 _b0[15] = _i & 0xff; \ 495 rijndael_encrypt(&ctx->cc_aes, _b0, _b); \ 496 xor_block(_pos, _b, _len); \ 497 /* Authentication */ \ 498 xor_block(_a, _pos, _len); \ 499 rijndael_encrypt(&ctx->cc_aes, _a, _a); \ 500 } while (0) 501 502 static int 503 ccmp_decrypt(struct ieee80211_key *key, u_int64_t pn, struct mbuf *m, int hdrlen) 504 { 505 struct ccmp_ctx *ctx = key->wk_private; 506 struct ieee80211_frame *wh; 507 uint8_t aad[2 * AES_BLOCK_LEN]; 508 uint8_t b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN], a[AES_BLOCK_LEN]; 509 uint8_t mic[AES_BLOCK_LEN]; 510 size_t data_len; 511 int i; 512 uint8_t *pos; 513 u_int space; 514 515 ctx->cc_ic->ic_stats.is_crypto_ccmp++; 516 517 wh = mtod(m, struct ieee80211_frame *); 518 data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header + ccmp.ic_trailer); 519 ccmp_init_blocks(&ctx->cc_aes, wh, pn, data_len, b0, aad, a, b); 520 m_copydata(m, m->m_pkthdr.len - ccmp.ic_trailer, ccmp.ic_trailer, mic); 521 xor_block(mic, b, ccmp.ic_trailer); 522 523 i = 1; 524 pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header; 525 space = m->m_len - (hdrlen + ccmp.ic_header); 526 for (;;) { 527 if (space > data_len) 528 space = data_len; 529 while (space >= AES_BLOCK_LEN) { 530 CCMP_DECRYPT(i, b, b0, pos, a, AES_BLOCK_LEN); 531 pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN; 532 data_len -= AES_BLOCK_LEN; 533 i++; 534 } 535 if (data_len <= 0) /* no more data */ 536 break; 537 m = m->m_next; 538 if (m == NULL) { /* last buffer */ 539 if (space != 0) /* short last block */ 540 CCMP_DECRYPT(i, b, b0, pos, a, space); 541 break; 542 } 543 if (space != 0) { 544 uint8_t *pos_next; 545 u_int space_next; 546 u_int len; 547 548 /* 549 * Block straddles buffers, split references. We 550 * do not handle splits that require >2 buffers. 551 */ 552 pos_next = mtod(m, uint8_t *); 553 len = min(data_len, AES_BLOCK_LEN); 554 space_next = len > space ? len - space : 0; 555 IASSERT(m->m_len >= space_next, 556 ("not enough data in following buffer, " 557 "m_len %u need %u\n", m->m_len, space_next)); 558 559 xor_block(b+space, pos_next, space_next); 560 CCMP_DECRYPT(i, b, b0, pos, a, space); 561 xor_block(pos_next, b+space, space_next); 562 data_len -= len; 563 i++; 564 565 pos = pos_next + space_next; 566 space = m->m_len - space_next; 567 } else { 568 /* 569 * Setup for next buffer. 570 */ 571 pos = mtod(m, uint8_t *); 572 space = m->m_len; 573 } 574 } 575 if (memcmp(mic, a, ccmp.ic_trailer) != 0) { 576 IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO, 577 "[%s] AES-CCM decrypt failed; MIC mismatch\n", 578 ether_sprintf(wh->i_addr2)); 579 ctx->cc_ic->ic_stats.is_rx_ccmpmic++; 580 return 0; 581 } 582 return 1; 583 } 584 #undef CCMP_DECRYPT 585