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; 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 tail; 36 37 hdr = (struct ieee80211_hdr *)skb->data; 38 if (!tx->key || tx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP || 39 skb->len < 24 || !ieee80211_is_data_present(hdr->frame_control)) 40 return TX_CONTINUE; 41 42 hdrlen = ieee80211_hdrlen(hdr->frame_control); 43 if (skb->len < hdrlen) 44 return TX_DROP; 45 46 data = skb->data + hdrlen; 47 data_len = skb->len - hdrlen; 48 49 if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE)) { 50 /* Need to use software crypto for the test */ 51 info->control.hw_key = NULL; 52 } 53 54 if (info->control.hw_key && 55 !(tx->flags & IEEE80211_TX_FRAGMENTED) && 56 !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) { 57 /* hwaccel - with no need for SW-generated MMIC */ 58 return TX_CONTINUE; 59 } 60 61 tail = MICHAEL_MIC_LEN; 62 if (!info->control.hw_key) 63 tail += TKIP_ICV_LEN; 64 65 if (WARN_ON(skb_tailroom(skb) < tail || 66 skb_headroom(skb) < TKIP_IV_LEN)) 67 return TX_DROP; 68 69 key = &tx->key->conf.key[NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY]; 70 mic = skb_put(skb, MICHAEL_MIC_LEN); 71 michael_mic(key, hdr, data, data_len, mic); 72 if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE)) 73 mic[0]++; 74 75 return TX_CONTINUE; 76 } 77 78 79 ieee80211_rx_result 80 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx) 81 { 82 u8 *data, *key = NULL; 83 size_t data_len; 84 unsigned int hdrlen; 85 u8 mic[MICHAEL_MIC_LEN]; 86 struct sk_buff *skb = rx->skb; 87 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 88 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; 89 90 /* 91 * it makes no sense to check for MIC errors on anything other 92 * than data frames. 93 */ 94 if (!ieee80211_is_data_present(hdr->frame_control)) 95 return RX_CONTINUE; 96 97 /* 98 * No way to verify the MIC if the hardware stripped it or 99 * the IV with the key index. In this case we have solely rely 100 * on the driver to set RX_FLAG_MMIC_ERROR in the event of a 101 * MIC failure report. 102 */ 103 if (status->flag & (RX_FLAG_MMIC_STRIPPED | RX_FLAG_IV_STRIPPED)) { 104 if (status->flag & RX_FLAG_MMIC_ERROR) 105 goto mic_fail; 106 107 if (!(status->flag & RX_FLAG_IV_STRIPPED)) 108 goto update_iv; 109 110 return RX_CONTINUE; 111 } 112 113 /* 114 * Some hardware seems to generate Michael MIC failure reports; even 115 * though, the frame was not encrypted with TKIP and therefore has no 116 * MIC. Ignore the flag them to avoid triggering countermeasures. 117 */ 118 if (!rx->key || rx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP || 119 !(status->flag & RX_FLAG_DECRYPTED)) 120 return RX_CONTINUE; 121 122 if (rx->sdata->vif.type == NL80211_IFTYPE_AP && rx->key->conf.keyidx) { 123 /* 124 * APs with pairwise keys should never receive Michael MIC 125 * errors for non-zero keyidx because these are reserved for 126 * group keys and only the AP is sending real multicast 127 * frames in the BSS. ( 128 */ 129 return RX_DROP_UNUSABLE; 130 } 131 132 if (status->flag & RX_FLAG_MMIC_ERROR) 133 goto mic_fail; 134 135 hdrlen = ieee80211_hdrlen(hdr->frame_control); 136 if (skb->len < hdrlen + MICHAEL_MIC_LEN) 137 return RX_DROP_UNUSABLE; 138 139 data = skb->data + hdrlen; 140 data_len = skb->len - hdrlen - MICHAEL_MIC_LEN; 141 key = &rx->key->conf.key[NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY]; 142 michael_mic(key, hdr, data, data_len, mic); 143 if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0) 144 goto mic_fail; 145 146 /* remove Michael MIC from payload */ 147 skb_trim(skb, skb->len - MICHAEL_MIC_LEN); 148 149 update_iv: 150 /* update IV in key information to be able to detect replays */ 151 rx->key->u.tkip.rx[rx->queue].iv32 = rx->tkip_iv32; 152 rx->key->u.tkip.rx[rx->queue].iv16 = rx->tkip_iv16; 153 154 return RX_CONTINUE; 155 156 mic_fail: 157 mac80211_ev_michael_mic_failure(rx->sdata, rx->key->conf.keyidx, 158 (void *) skb->data, NULL, GFP_ATOMIC); 159 return RX_DROP_UNUSABLE; 160 } 161 162 163 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) 164 { 165 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 166 struct ieee80211_key *key = tx->key; 167 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 168 unsigned int hdrlen; 169 int len, tail; 170 u8 *pos; 171 172 if (info->control.hw_key && 173 !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) { 174 /* hwaccel - with no need for software-generated IV */ 175 return 0; 176 } 177 178 hdrlen = ieee80211_hdrlen(hdr->frame_control); 179 len = skb->len - hdrlen; 180 181 if (info->control.hw_key) 182 tail = 0; 183 else 184 tail = TKIP_ICV_LEN; 185 186 if (WARN_ON(skb_tailroom(skb) < tail || 187 skb_headroom(skb) < TKIP_IV_LEN)) 188 return -1; 189 190 pos = skb_push(skb, TKIP_IV_LEN); 191 memmove(pos, pos + TKIP_IV_LEN, hdrlen); 192 pos += hdrlen; 193 194 /* Increase IV for the frame */ 195 key->u.tkip.tx.iv16++; 196 if (key->u.tkip.tx.iv16 == 0) 197 key->u.tkip.tx.iv32++; 198 199 pos = ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16); 200 201 /* hwaccel - with software IV */ 202 if (info->control.hw_key) 203 return 0; 204 205 /* Add room for ICV */ 206 skb_put(skb, TKIP_ICV_LEN); 207 208 hdr = (struct ieee80211_hdr *) skb->data; 209 return ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm, 210 key, pos, len, hdr->addr2); 211 } 212 213 214 ieee80211_tx_result 215 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx) 216 { 217 struct sk_buff *skb = tx->skb; 218 219 ieee80211_tx_set_protected(tx); 220 221 do { 222 if (tkip_encrypt_skb(tx, skb) < 0) 223 return TX_DROP; 224 } while ((skb = skb->next)); 225 226 return TX_CONTINUE; 227 } 228 229 230 ieee80211_rx_result 231 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx) 232 { 233 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data; 234 int hdrlen, res, hwaccel = 0; 235 struct ieee80211_key *key = rx->key; 236 struct sk_buff *skb = rx->skb; 237 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 238 239 hdrlen = ieee80211_hdrlen(hdr->frame_control); 240 241 if (!ieee80211_is_data(hdr->frame_control)) 242 return RX_CONTINUE; 243 244 if (!rx->sta || skb->len - hdrlen < 12) 245 return RX_DROP_UNUSABLE; 246 247 /* 248 * Let TKIP code verify IV, but skip decryption. 249 * In the case where hardware checks the IV as well, 250 * we don't even get here, see ieee80211_rx_h_decrypt() 251 */ 252 if (status->flag & RX_FLAG_DECRYPTED) 253 hwaccel = 1; 254 255 res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm, 256 key, skb->data + hdrlen, 257 skb->len - hdrlen, rx->sta->sta.addr, 258 hdr->addr1, hwaccel, rx->queue, 259 &rx->tkip_iv32, 260 &rx->tkip_iv16); 261 if (res != TKIP_DECRYPT_OK) 262 return RX_DROP_UNUSABLE; 263 264 /* Trim ICV */ 265 skb_trim(skb, skb->len - TKIP_ICV_LEN); 266 267 /* Remove IV */ 268 memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen); 269 skb_pull(skb, TKIP_IV_LEN); 270 271 return RX_CONTINUE; 272 } 273 274 275 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch, 276 int encrypted) 277 { 278 __le16 mask_fc; 279 int a4_included, mgmt; 280 u8 qos_tid; 281 u8 *b_0, *aad; 282 u16 data_len, len_a; 283 unsigned int hdrlen; 284 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; 285 286 b_0 = scratch + 3 * AES_BLOCK_LEN; 287 aad = scratch + 4 * AES_BLOCK_LEN; 288 289 /* 290 * Mask FC: zero subtype b4 b5 b6 (if not mgmt) 291 * Retry, PwrMgt, MoreData; set Protected 292 */ 293 mgmt = ieee80211_is_mgmt(hdr->frame_control); 294 mask_fc = hdr->frame_control; 295 mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY | 296 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA); 297 if (!mgmt) 298 mask_fc &= ~cpu_to_le16(0x0070); 299 mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); 300 301 hdrlen = ieee80211_hdrlen(hdr->frame_control); 302 len_a = hdrlen - 2; 303 a4_included = ieee80211_has_a4(hdr->frame_control); 304 305 if (ieee80211_is_data_qos(hdr->frame_control)) 306 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK; 307 else 308 qos_tid = 0; 309 310 data_len = skb->len - hdrlen - CCMP_HDR_LEN; 311 if (encrypted) 312 data_len -= CCMP_MIC_LEN; 313 314 /* First block, b_0 */ 315 b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */ 316 /* Nonce: Nonce Flags | A2 | PN 317 * Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7) 318 */ 319 b_0[1] = qos_tid | (mgmt << 4); 320 memcpy(&b_0[2], hdr->addr2, ETH_ALEN); 321 memcpy(&b_0[8], pn, CCMP_PN_LEN); 322 /* l(m) */ 323 put_unaligned_be16(data_len, &b_0[14]); 324 325 /* AAD (extra authenticate-only data) / masked 802.11 header 326 * FC | A1 | A2 | A3 | SC | [A4] | [QC] */ 327 put_unaligned_be16(len_a, &aad[0]); 328 put_unaligned(mask_fc, (__le16 *)&aad[2]); 329 memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN); 330 331 /* Mask Seq#, leave Frag# */ 332 aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f; 333 aad[23] = 0; 334 335 if (a4_included) { 336 memcpy(&aad[24], hdr->addr4, ETH_ALEN); 337 aad[30] = qos_tid; 338 aad[31] = 0; 339 } else { 340 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN); 341 aad[24] = qos_tid; 342 } 343 } 344 345 346 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id) 347 { 348 hdr[0] = pn[5]; 349 hdr[1] = pn[4]; 350 hdr[2] = 0; 351 hdr[3] = 0x20 | (key_id << 6); 352 hdr[4] = pn[3]; 353 hdr[5] = pn[2]; 354 hdr[6] = pn[1]; 355 hdr[7] = pn[0]; 356 } 357 358 359 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr) 360 { 361 pn[0] = hdr[7]; 362 pn[1] = hdr[6]; 363 pn[2] = hdr[5]; 364 pn[3] = hdr[4]; 365 pn[4] = hdr[1]; 366 pn[5] = hdr[0]; 367 } 368 369 370 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) 371 { 372 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 373 struct ieee80211_key *key = tx->key; 374 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 375 int hdrlen, len, tail; 376 u8 *pos, *pn; 377 int i; 378 379 if (info->control.hw_key && 380 !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) { 381 /* 382 * hwaccel has no need for preallocated room for CCMP 383 * header or MIC fields 384 */ 385 return 0; 386 } 387 388 hdrlen = ieee80211_hdrlen(hdr->frame_control); 389 len = skb->len - hdrlen; 390 391 if (info->control.hw_key) 392 tail = 0; 393 else 394 tail = CCMP_MIC_LEN; 395 396 if (WARN_ON(skb_tailroom(skb) < tail || 397 skb_headroom(skb) < CCMP_HDR_LEN)) 398 return -1; 399 400 pos = skb_push(skb, CCMP_HDR_LEN); 401 memmove(pos, pos + CCMP_HDR_LEN, hdrlen); 402 hdr = (struct ieee80211_hdr *) pos; 403 pos += hdrlen; 404 405 /* PN = PN + 1 */ 406 pn = key->u.ccmp.tx_pn; 407 408 for (i = CCMP_PN_LEN - 1; i >= 0; i--) { 409 pn[i]++; 410 if (pn[i]) 411 break; 412 } 413 414 ccmp_pn2hdr(pos, pn, key->conf.keyidx); 415 416 /* hwaccel - with software CCMP header */ 417 if (info->control.hw_key) 418 return 0; 419 420 pos += CCMP_HDR_LEN; 421 ccmp_special_blocks(skb, pn, key->u.ccmp.tx_crypto_buf, 0); 422 ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, key->u.ccmp.tx_crypto_buf, pos, len, 423 pos, skb_put(skb, CCMP_MIC_LEN)); 424 425 return 0; 426 } 427 428 429 ieee80211_tx_result 430 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx) 431 { 432 struct sk_buff *skb = tx->skb; 433 434 ieee80211_tx_set_protected(tx); 435 436 do { 437 if (ccmp_encrypt_skb(tx, skb) < 0) 438 return TX_DROP; 439 } while ((skb = skb->next)); 440 441 return TX_CONTINUE; 442 } 443 444 445 ieee80211_rx_result 446 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx) 447 { 448 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data; 449 int hdrlen; 450 struct ieee80211_key *key = rx->key; 451 struct sk_buff *skb = rx->skb; 452 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 453 u8 pn[CCMP_PN_LEN]; 454 int data_len; 455 int queue; 456 457 hdrlen = ieee80211_hdrlen(hdr->frame_control); 458 459 if (!ieee80211_is_data(hdr->frame_control) && 460 !ieee80211_is_robust_mgmt_frame(hdr)) 461 return RX_CONTINUE; 462 463 data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN; 464 if (!rx->sta || data_len < 0) 465 return RX_DROP_UNUSABLE; 466 467 ccmp_hdr2pn(pn, skb->data + hdrlen); 468 469 queue = ieee80211_is_mgmt(hdr->frame_control) ? 470 NUM_RX_DATA_QUEUES : rx->queue; 471 472 if (memcmp(pn, key->u.ccmp.rx_pn[queue], CCMP_PN_LEN) <= 0) { 473 key->u.ccmp.replays++; 474 return RX_DROP_UNUSABLE; 475 } 476 477 if (!(status->flag & RX_FLAG_DECRYPTED)) { 478 /* hardware didn't decrypt/verify MIC */ 479 ccmp_special_blocks(skb, pn, key->u.ccmp.rx_crypto_buf, 1); 480 481 if (ieee80211_aes_ccm_decrypt( 482 key->u.ccmp.tfm, key->u.ccmp.rx_crypto_buf, 483 skb->data + hdrlen + CCMP_HDR_LEN, data_len, 484 skb->data + skb->len - CCMP_MIC_LEN, 485 skb->data + hdrlen + CCMP_HDR_LEN)) 486 return RX_DROP_UNUSABLE; 487 } 488 489 memcpy(key->u.ccmp.rx_pn[queue], pn, CCMP_PN_LEN); 490 491 /* Remove CCMP header and MIC */ 492 skb_trim(skb, skb->len - CCMP_MIC_LEN); 493 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen); 494 skb_pull(skb, CCMP_HDR_LEN); 495 496 return RX_CONTINUE; 497 } 498 499 500 static void bip_aad(struct sk_buff *skb, u8 *aad) 501 { 502 /* BIP AAD: FC(masked) || A1 || A2 || A3 */ 503 504 /* FC type/subtype */ 505 aad[0] = skb->data[0]; 506 /* Mask FC Retry, PwrMgt, MoreData flags to zero */ 507 aad[1] = skb->data[1] & ~(BIT(4) | BIT(5) | BIT(6)); 508 /* A1 || A2 || A3 */ 509 memcpy(aad + 2, skb->data + 4, 3 * ETH_ALEN); 510 } 511 512 513 static inline void bip_ipn_swap(u8 *d, const u8 *s) 514 { 515 *d++ = s[5]; 516 *d++ = s[4]; 517 *d++ = s[3]; 518 *d++ = s[2]; 519 *d++ = s[1]; 520 *d = s[0]; 521 } 522 523 524 ieee80211_tx_result 525 ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx) 526 { 527 struct sk_buff *skb = tx->skb; 528 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 529 struct ieee80211_key *key = tx->key; 530 struct ieee80211_mmie *mmie; 531 u8 *pn, aad[20]; 532 int i; 533 534 if (info->control.hw_key) 535 return 0; 536 537 if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie))) 538 return TX_DROP; 539 540 mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie)); 541 mmie->element_id = WLAN_EID_MMIE; 542 mmie->length = sizeof(*mmie) - 2; 543 mmie->key_id = cpu_to_le16(key->conf.keyidx); 544 545 /* PN = PN + 1 */ 546 pn = key->u.aes_cmac.tx_pn; 547 548 for (i = sizeof(key->u.aes_cmac.tx_pn) - 1; i >= 0; i--) { 549 pn[i]++; 550 if (pn[i]) 551 break; 552 } 553 bip_ipn_swap(mmie->sequence_number, pn); 554 555 bip_aad(skb, aad); 556 557 /* 558 * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64) 559 */ 560 ieee80211_aes_cmac(key->u.aes_cmac.tfm, key->u.aes_cmac.tx_crypto_buf, 561 aad, skb->data + 24, skb->len - 24, mmie->mic); 562 563 return TX_CONTINUE; 564 } 565 566 567 ieee80211_rx_result 568 ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx) 569 { 570 struct sk_buff *skb = rx->skb; 571 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 572 struct ieee80211_key *key = rx->key; 573 struct ieee80211_mmie *mmie; 574 u8 aad[20], mic[8], ipn[6]; 575 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 576 577 if (!ieee80211_is_mgmt(hdr->frame_control)) 578 return RX_CONTINUE; 579 580 if (skb->len < 24 + sizeof(*mmie)) 581 return RX_DROP_UNUSABLE; 582 583 mmie = (struct ieee80211_mmie *) 584 (skb->data + skb->len - sizeof(*mmie)); 585 if (mmie->element_id != WLAN_EID_MMIE || 586 mmie->length != sizeof(*mmie) - 2) 587 return RX_DROP_UNUSABLE; /* Invalid MMIE */ 588 589 bip_ipn_swap(ipn, mmie->sequence_number); 590 591 if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) { 592 key->u.aes_cmac.replays++; 593 return RX_DROP_UNUSABLE; 594 } 595 596 if (!(status->flag & RX_FLAG_DECRYPTED)) { 597 /* hardware didn't decrypt/verify MIC */ 598 bip_aad(skb, aad); 599 ieee80211_aes_cmac(key->u.aes_cmac.tfm, 600 key->u.aes_cmac.rx_crypto_buf, aad, 601 skb->data + 24, skb->len - 24, mic); 602 if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) { 603 key->u.aes_cmac.icverrors++; 604 return RX_DROP_UNUSABLE; 605 } 606 } 607 608 memcpy(key->u.aes_cmac.rx_pn, ipn, 6); 609 610 /* Remove MMIE */ 611 skb_trim(skb, skb->len - sizeof(*mmie)); 612 613 return RX_CONTINUE; 614 } 615