1 /* 2 * Copyright 2002-2004, Instant802 Networks, Inc. 3 * Copyright 2008, Jouni Malinen <j@w1.fi> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 */ 9 10 #include <linux/netdevice.h> 11 #include <linux/types.h> 12 #include <linux/skbuff.h> 13 #include <linux/compiler.h> 14 #include <linux/ieee80211.h> 15 #include <linux/gfp.h> 16 #include <asm/unaligned.h> 17 #include <net/mac80211.h> 18 19 #include "ieee80211_i.h" 20 #include "michael.h" 21 #include "tkip.h" 22 #include "aes_ccm.h" 23 #include "aes_cmac.h" 24 #include "wpa.h" 25 26 ieee80211_tx_result 27 ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx) 28 { 29 u8 *data, *key, *mic, key_offset; 30 size_t data_len; 31 unsigned int hdrlen; 32 struct ieee80211_hdr *hdr; 33 struct sk_buff *skb = tx->skb; 34 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 35 int authenticator; 36 int tail; 37 38 hdr = (struct ieee80211_hdr *)skb->data; 39 if (!tx->key || tx->key->conf.alg != ALG_TKIP || skb->len < 24 || 40 !ieee80211_is_data_present(hdr->frame_control)) 41 return TX_CONTINUE; 42 43 hdrlen = ieee80211_hdrlen(hdr->frame_control); 44 if (skb->len < hdrlen) 45 return TX_DROP; 46 47 data = skb->data + hdrlen; 48 data_len = skb->len - hdrlen; 49 50 if (info->control.hw_key && 51 !(tx->flags & IEEE80211_TX_FRAGMENTED) && 52 !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) { 53 /* hwaccel - with no need for SW-generated MMIC */ 54 return TX_CONTINUE; 55 } 56 57 tail = MICHAEL_MIC_LEN; 58 if (!info->control.hw_key) 59 tail += TKIP_ICV_LEN; 60 61 if (WARN_ON(skb_tailroom(skb) < tail || 62 skb_headroom(skb) < TKIP_IV_LEN)) 63 return TX_DROP; 64 65 #if 0 66 authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */ 67 #else 68 authenticator = 1; 69 #endif 70 key_offset = authenticator ? 71 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY : 72 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY; 73 key = &tx->key->conf.key[key_offset]; 74 mic = skb_put(skb, MICHAEL_MIC_LEN); 75 michael_mic(key, hdr, data, data_len, mic); 76 77 return TX_CONTINUE; 78 } 79 80 81 ieee80211_rx_result 82 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx) 83 { 84 u8 *data, *key = NULL, key_offset; 85 size_t data_len; 86 unsigned int hdrlen; 87 u8 mic[MICHAEL_MIC_LEN]; 88 struct sk_buff *skb = rx->skb; 89 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 90 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; 91 int authenticator = 1, wpa_test = 0; 92 93 /* No way to verify the MIC if the hardware stripped it */ 94 if (status->flag & RX_FLAG_MMIC_STRIPPED) 95 return RX_CONTINUE; 96 97 if (!rx->key || rx->key->conf.alg != ALG_TKIP || 98 !ieee80211_has_protected(hdr->frame_control) || 99 !ieee80211_is_data_present(hdr->frame_control)) 100 return RX_CONTINUE; 101 102 hdrlen = ieee80211_hdrlen(hdr->frame_control); 103 if (skb->len < hdrlen + MICHAEL_MIC_LEN) 104 return RX_DROP_UNUSABLE; 105 106 data = skb->data + hdrlen; 107 data_len = skb->len - hdrlen - MICHAEL_MIC_LEN; 108 109 #if 0 110 authenticator = fc & IEEE80211_FCTL_TODS; /* FIX */ 111 #else 112 authenticator = 1; 113 #endif 114 key_offset = authenticator ? 115 NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY : 116 NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY; 117 key = &rx->key->conf.key[key_offset]; 118 michael_mic(key, hdr, data, data_len, mic); 119 if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0 || wpa_test) { 120 if (!(rx->flags & IEEE80211_RX_RA_MATCH)) 121 return RX_DROP_UNUSABLE; 122 123 mac80211_ev_michael_mic_failure(rx->sdata, rx->key->conf.keyidx, 124 (void *) skb->data, NULL, 125 GFP_ATOMIC); 126 return RX_DROP_UNUSABLE; 127 } 128 129 /* remove Michael MIC from payload */ 130 skb_trim(skb, skb->len - MICHAEL_MIC_LEN); 131 132 /* update IV in key information to be able to detect replays */ 133 rx->key->u.tkip.rx[rx->queue].iv32 = rx->tkip_iv32; 134 rx->key->u.tkip.rx[rx->queue].iv16 = rx->tkip_iv16; 135 136 return RX_CONTINUE; 137 } 138 139 140 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) 141 { 142 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 143 struct ieee80211_key *key = tx->key; 144 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 145 unsigned int hdrlen; 146 int len, tail; 147 u8 *pos; 148 149 if (info->control.hw_key && 150 !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) { 151 /* hwaccel - with no need for software-generated IV */ 152 return 0; 153 } 154 155 hdrlen = ieee80211_hdrlen(hdr->frame_control); 156 len = skb->len - hdrlen; 157 158 if (info->control.hw_key) 159 tail = 0; 160 else 161 tail = TKIP_ICV_LEN; 162 163 if (WARN_ON(skb_tailroom(skb) < tail || 164 skb_headroom(skb) < TKIP_IV_LEN)) 165 return -1; 166 167 pos = skb_push(skb, TKIP_IV_LEN); 168 memmove(pos, pos + TKIP_IV_LEN, hdrlen); 169 pos += hdrlen; 170 171 /* Increase IV for the frame */ 172 key->u.tkip.tx.iv16++; 173 if (key->u.tkip.tx.iv16 == 0) 174 key->u.tkip.tx.iv32++; 175 176 pos = ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16); 177 178 /* hwaccel - with software IV */ 179 if (info->control.hw_key) 180 return 0; 181 182 /* Add room for ICV */ 183 skb_put(skb, TKIP_ICV_LEN); 184 185 hdr = (struct ieee80211_hdr *) skb->data; 186 return ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm, 187 key, pos, len, hdr->addr2); 188 } 189 190 191 ieee80211_tx_result 192 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx) 193 { 194 struct sk_buff *skb = tx->skb; 195 196 ieee80211_tx_set_protected(tx); 197 198 do { 199 if (tkip_encrypt_skb(tx, skb) < 0) 200 return TX_DROP; 201 } while ((skb = skb->next)); 202 203 return TX_CONTINUE; 204 } 205 206 207 ieee80211_rx_result 208 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx) 209 { 210 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data; 211 int hdrlen, res, hwaccel = 0, wpa_test = 0; 212 struct ieee80211_key *key = rx->key; 213 struct sk_buff *skb = rx->skb; 214 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 215 216 hdrlen = ieee80211_hdrlen(hdr->frame_control); 217 218 if (!ieee80211_is_data(hdr->frame_control)) 219 return RX_CONTINUE; 220 221 if (!rx->sta || skb->len - hdrlen < 12) 222 return RX_DROP_UNUSABLE; 223 224 if (status->flag & RX_FLAG_DECRYPTED) { 225 if (status->flag & RX_FLAG_IV_STRIPPED) { 226 /* 227 * Hardware took care of all processing, including 228 * replay protection, and stripped the ICV/IV so 229 * we cannot do any checks here. 230 */ 231 return RX_CONTINUE; 232 } 233 234 /* let TKIP code verify IV, but skip decryption */ 235 hwaccel = 1; 236 } 237 238 res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm, 239 key, skb->data + hdrlen, 240 skb->len - hdrlen, rx->sta->sta.addr, 241 hdr->addr1, hwaccel, rx->queue, 242 &rx->tkip_iv32, 243 &rx->tkip_iv16); 244 if (res != TKIP_DECRYPT_OK || wpa_test) 245 return RX_DROP_UNUSABLE; 246 247 /* Trim ICV */ 248 skb_trim(skb, skb->len - TKIP_ICV_LEN); 249 250 /* Remove IV */ 251 memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen); 252 skb_pull(skb, TKIP_IV_LEN); 253 254 return RX_CONTINUE; 255 } 256 257 258 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch, 259 int encrypted) 260 { 261 __le16 mask_fc; 262 int a4_included, mgmt; 263 u8 qos_tid; 264 u8 *b_0, *aad; 265 u16 data_len, len_a; 266 unsigned int hdrlen; 267 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; 268 269 b_0 = scratch + 3 * AES_BLOCK_LEN; 270 aad = scratch + 4 * AES_BLOCK_LEN; 271 272 /* 273 * Mask FC: zero subtype b4 b5 b6 (if not mgmt) 274 * Retry, PwrMgt, MoreData; set Protected 275 */ 276 mgmt = ieee80211_is_mgmt(hdr->frame_control); 277 mask_fc = hdr->frame_control; 278 mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY | 279 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA); 280 if (!mgmt) 281 mask_fc &= ~cpu_to_le16(0x0070); 282 mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); 283 284 hdrlen = ieee80211_hdrlen(hdr->frame_control); 285 len_a = hdrlen - 2; 286 a4_included = ieee80211_has_a4(hdr->frame_control); 287 288 if (ieee80211_is_data_qos(hdr->frame_control)) 289 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK; 290 else 291 qos_tid = 0; 292 293 data_len = skb->len - hdrlen - CCMP_HDR_LEN; 294 if (encrypted) 295 data_len -= CCMP_MIC_LEN; 296 297 /* First block, b_0 */ 298 b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */ 299 /* Nonce: Nonce Flags | A2 | PN 300 * Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7) 301 */ 302 b_0[1] = qos_tid | (mgmt << 4); 303 memcpy(&b_0[2], hdr->addr2, ETH_ALEN); 304 memcpy(&b_0[8], pn, CCMP_PN_LEN); 305 /* l(m) */ 306 put_unaligned_be16(data_len, &b_0[14]); 307 308 /* AAD (extra authenticate-only data) / masked 802.11 header 309 * FC | A1 | A2 | A3 | SC | [A4] | [QC] */ 310 put_unaligned_be16(len_a, &aad[0]); 311 put_unaligned(mask_fc, (__le16 *)&aad[2]); 312 memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN); 313 314 /* Mask Seq#, leave Frag# */ 315 aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f; 316 aad[23] = 0; 317 318 if (a4_included) { 319 memcpy(&aad[24], hdr->addr4, ETH_ALEN); 320 aad[30] = qos_tid; 321 aad[31] = 0; 322 } else { 323 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN); 324 aad[24] = qos_tid; 325 } 326 } 327 328 329 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id) 330 { 331 hdr[0] = pn[5]; 332 hdr[1] = pn[4]; 333 hdr[2] = 0; 334 hdr[3] = 0x20 | (key_id << 6); 335 hdr[4] = pn[3]; 336 hdr[5] = pn[2]; 337 hdr[6] = pn[1]; 338 hdr[7] = pn[0]; 339 } 340 341 342 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr) 343 { 344 pn[0] = hdr[7]; 345 pn[1] = hdr[6]; 346 pn[2] = hdr[5]; 347 pn[3] = hdr[4]; 348 pn[4] = hdr[1]; 349 pn[5] = hdr[0]; 350 } 351 352 353 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) 354 { 355 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 356 struct ieee80211_key *key = tx->key; 357 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 358 int hdrlen, len, tail; 359 u8 *pos, *pn; 360 int i; 361 362 if (info->control.hw_key && 363 !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) { 364 /* 365 * hwaccel has no need for preallocated room for CCMP 366 * header or MIC fields 367 */ 368 return 0; 369 } 370 371 hdrlen = ieee80211_hdrlen(hdr->frame_control); 372 len = skb->len - hdrlen; 373 374 if (info->control.hw_key) 375 tail = 0; 376 else 377 tail = CCMP_MIC_LEN; 378 379 if (WARN_ON(skb_tailroom(skb) < tail || 380 skb_headroom(skb) < CCMP_HDR_LEN)) 381 return -1; 382 383 pos = skb_push(skb, CCMP_HDR_LEN); 384 memmove(pos, pos + CCMP_HDR_LEN, hdrlen); 385 hdr = (struct ieee80211_hdr *) pos; 386 pos += hdrlen; 387 388 /* PN = PN + 1 */ 389 pn = key->u.ccmp.tx_pn; 390 391 for (i = CCMP_PN_LEN - 1; i >= 0; i--) { 392 pn[i]++; 393 if (pn[i]) 394 break; 395 } 396 397 ccmp_pn2hdr(pos, pn, key->conf.keyidx); 398 399 /* hwaccel - with software CCMP header */ 400 if (info->control.hw_key) 401 return 0; 402 403 pos += CCMP_HDR_LEN; 404 ccmp_special_blocks(skb, pn, key->u.ccmp.tx_crypto_buf, 0); 405 ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, key->u.ccmp.tx_crypto_buf, pos, len, 406 pos, skb_put(skb, CCMP_MIC_LEN)); 407 408 return 0; 409 } 410 411 412 ieee80211_tx_result 413 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx) 414 { 415 struct sk_buff *skb = tx->skb; 416 417 ieee80211_tx_set_protected(tx); 418 419 do { 420 if (ccmp_encrypt_skb(tx, skb) < 0) 421 return TX_DROP; 422 } while ((skb = skb->next)); 423 424 return TX_CONTINUE; 425 } 426 427 428 ieee80211_rx_result 429 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx) 430 { 431 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data; 432 int hdrlen; 433 struct ieee80211_key *key = rx->key; 434 struct sk_buff *skb = rx->skb; 435 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 436 u8 pn[CCMP_PN_LEN]; 437 int data_len; 438 int queue; 439 440 hdrlen = ieee80211_hdrlen(hdr->frame_control); 441 442 if (!ieee80211_is_data(hdr->frame_control) && 443 !ieee80211_is_robust_mgmt_frame(hdr)) 444 return RX_CONTINUE; 445 446 data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN; 447 if (!rx->sta || data_len < 0) 448 return RX_DROP_UNUSABLE; 449 450 if ((status->flag & RX_FLAG_DECRYPTED) && 451 (status->flag & RX_FLAG_IV_STRIPPED)) 452 return RX_CONTINUE; 453 454 ccmp_hdr2pn(pn, skb->data + hdrlen); 455 456 queue = ieee80211_is_mgmt(hdr->frame_control) ? 457 NUM_RX_DATA_QUEUES : rx->queue; 458 459 if (memcmp(pn, key->u.ccmp.rx_pn[queue], CCMP_PN_LEN) <= 0) { 460 key->u.ccmp.replays++; 461 return RX_DROP_UNUSABLE; 462 } 463 464 if (!(status->flag & RX_FLAG_DECRYPTED)) { 465 /* hardware didn't decrypt/verify MIC */ 466 ccmp_special_blocks(skb, pn, key->u.ccmp.rx_crypto_buf, 1); 467 468 if (ieee80211_aes_ccm_decrypt( 469 key->u.ccmp.tfm, key->u.ccmp.rx_crypto_buf, 470 skb->data + hdrlen + CCMP_HDR_LEN, data_len, 471 skb->data + skb->len - CCMP_MIC_LEN, 472 skb->data + hdrlen + CCMP_HDR_LEN)) 473 return RX_DROP_UNUSABLE; 474 } 475 476 memcpy(key->u.ccmp.rx_pn[queue], pn, CCMP_PN_LEN); 477 478 /* Remove CCMP header and MIC */ 479 skb_trim(skb, skb->len - CCMP_MIC_LEN); 480 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen); 481 skb_pull(skb, CCMP_HDR_LEN); 482 483 return RX_CONTINUE; 484 } 485 486 487 static void bip_aad(struct sk_buff *skb, u8 *aad) 488 { 489 /* BIP AAD: FC(masked) || A1 || A2 || A3 */ 490 491 /* FC type/subtype */ 492 aad[0] = skb->data[0]; 493 /* Mask FC Retry, PwrMgt, MoreData flags to zero */ 494 aad[1] = skb->data[1] & ~(BIT(4) | BIT(5) | BIT(6)); 495 /* A1 || A2 || A3 */ 496 memcpy(aad + 2, skb->data + 4, 3 * ETH_ALEN); 497 } 498 499 500 static inline void bip_ipn_swap(u8 *d, const u8 *s) 501 { 502 *d++ = s[5]; 503 *d++ = s[4]; 504 *d++ = s[3]; 505 *d++ = s[2]; 506 *d++ = s[1]; 507 *d = s[0]; 508 } 509 510 511 ieee80211_tx_result 512 ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx) 513 { 514 struct sk_buff *skb = tx->skb; 515 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 516 struct ieee80211_key *key = tx->key; 517 struct ieee80211_mmie *mmie; 518 u8 *pn, aad[20]; 519 int i; 520 521 if (info->control.hw_key) 522 return 0; 523 524 if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie))) 525 return TX_DROP; 526 527 mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie)); 528 mmie->element_id = WLAN_EID_MMIE; 529 mmie->length = sizeof(*mmie) - 2; 530 mmie->key_id = cpu_to_le16(key->conf.keyidx); 531 532 /* PN = PN + 1 */ 533 pn = key->u.aes_cmac.tx_pn; 534 535 for (i = sizeof(key->u.aes_cmac.tx_pn) - 1; i >= 0; i--) { 536 pn[i]++; 537 if (pn[i]) 538 break; 539 } 540 bip_ipn_swap(mmie->sequence_number, pn); 541 542 bip_aad(skb, aad); 543 544 /* 545 * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64) 546 */ 547 ieee80211_aes_cmac(key->u.aes_cmac.tfm, key->u.aes_cmac.tx_crypto_buf, 548 aad, skb->data + 24, skb->len - 24, mmie->mic); 549 550 return TX_CONTINUE; 551 } 552 553 554 ieee80211_rx_result 555 ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx) 556 { 557 struct sk_buff *skb = rx->skb; 558 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 559 struct ieee80211_key *key = rx->key; 560 struct ieee80211_mmie *mmie; 561 u8 aad[20], mic[8], ipn[6]; 562 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 563 564 if (!ieee80211_is_mgmt(hdr->frame_control)) 565 return RX_CONTINUE; 566 567 if ((status->flag & RX_FLAG_DECRYPTED) && 568 (status->flag & RX_FLAG_IV_STRIPPED)) 569 return RX_CONTINUE; 570 571 if (skb->len < 24 + sizeof(*mmie)) 572 return RX_DROP_UNUSABLE; 573 574 mmie = (struct ieee80211_mmie *) 575 (skb->data + skb->len - sizeof(*mmie)); 576 if (mmie->element_id != WLAN_EID_MMIE || 577 mmie->length != sizeof(*mmie) - 2) 578 return RX_DROP_UNUSABLE; /* Invalid MMIE */ 579 580 bip_ipn_swap(ipn, mmie->sequence_number); 581 582 if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) { 583 key->u.aes_cmac.replays++; 584 return RX_DROP_UNUSABLE; 585 } 586 587 if (!(status->flag & RX_FLAG_DECRYPTED)) { 588 /* hardware didn't decrypt/verify MIC */ 589 bip_aad(skb, aad); 590 ieee80211_aes_cmac(key->u.aes_cmac.tfm, 591 key->u.aes_cmac.rx_crypto_buf, aad, 592 skb->data + 24, skb->len - 24, mic); 593 if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) { 594 key->u.aes_cmac.icverrors++; 595 return RX_DROP_UNUSABLE; 596 } 597 } 598 599 memcpy(key->u.aes_cmac.rx_pn, ipn, 6); 600 601 /* Remove MMIE */ 602 skb_trim(skb, skb->len - sizeof(*mmie)); 603 604 return RX_CONTINUE; 605 } 606