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.cipher != WLAN_CIPHER_SUITE_TKIP || 40 skb->len < 24 || !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.cipher != WLAN_CIPHER_SUITE_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 (!(status->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 /* 225 * Let TKIP code verify IV, but skip decryption. 226 * In the case where hardware checks the IV as well, 227 * we don't even get here, see ieee80211_rx_h_decrypt() 228 */ 229 if (status->flag & RX_FLAG_DECRYPTED) 230 hwaccel = 1; 231 232 res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm, 233 key, skb->data + hdrlen, 234 skb->len - hdrlen, rx->sta->sta.addr, 235 hdr->addr1, hwaccel, rx->queue, 236 &rx->tkip_iv32, 237 &rx->tkip_iv16); 238 if (res != TKIP_DECRYPT_OK || wpa_test) 239 return RX_DROP_UNUSABLE; 240 241 /* Trim ICV */ 242 skb_trim(skb, skb->len - TKIP_ICV_LEN); 243 244 /* Remove IV */ 245 memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen); 246 skb_pull(skb, TKIP_IV_LEN); 247 248 return RX_CONTINUE; 249 } 250 251 252 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch, 253 int encrypted) 254 { 255 __le16 mask_fc; 256 int a4_included, mgmt; 257 u8 qos_tid; 258 u8 *b_0, *aad; 259 u16 data_len, len_a; 260 unsigned int hdrlen; 261 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; 262 263 b_0 = scratch + 3 * AES_BLOCK_LEN; 264 aad = scratch + 4 * AES_BLOCK_LEN; 265 266 /* 267 * Mask FC: zero subtype b4 b5 b6 (if not mgmt) 268 * Retry, PwrMgt, MoreData; set Protected 269 */ 270 mgmt = ieee80211_is_mgmt(hdr->frame_control); 271 mask_fc = hdr->frame_control; 272 mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY | 273 IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA); 274 if (!mgmt) 275 mask_fc &= ~cpu_to_le16(0x0070); 276 mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); 277 278 hdrlen = ieee80211_hdrlen(hdr->frame_control); 279 len_a = hdrlen - 2; 280 a4_included = ieee80211_has_a4(hdr->frame_control); 281 282 if (ieee80211_is_data_qos(hdr->frame_control)) 283 qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK; 284 else 285 qos_tid = 0; 286 287 data_len = skb->len - hdrlen - CCMP_HDR_LEN; 288 if (encrypted) 289 data_len -= CCMP_MIC_LEN; 290 291 /* First block, b_0 */ 292 b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */ 293 /* Nonce: Nonce Flags | A2 | PN 294 * Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7) 295 */ 296 b_0[1] = qos_tid | (mgmt << 4); 297 memcpy(&b_0[2], hdr->addr2, ETH_ALEN); 298 memcpy(&b_0[8], pn, CCMP_PN_LEN); 299 /* l(m) */ 300 put_unaligned_be16(data_len, &b_0[14]); 301 302 /* AAD (extra authenticate-only data) / masked 802.11 header 303 * FC | A1 | A2 | A3 | SC | [A4] | [QC] */ 304 put_unaligned_be16(len_a, &aad[0]); 305 put_unaligned(mask_fc, (__le16 *)&aad[2]); 306 memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN); 307 308 /* Mask Seq#, leave Frag# */ 309 aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f; 310 aad[23] = 0; 311 312 if (a4_included) { 313 memcpy(&aad[24], hdr->addr4, ETH_ALEN); 314 aad[30] = qos_tid; 315 aad[31] = 0; 316 } else { 317 memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN); 318 aad[24] = qos_tid; 319 } 320 } 321 322 323 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id) 324 { 325 hdr[0] = pn[5]; 326 hdr[1] = pn[4]; 327 hdr[2] = 0; 328 hdr[3] = 0x20 | (key_id << 6); 329 hdr[4] = pn[3]; 330 hdr[5] = pn[2]; 331 hdr[6] = pn[1]; 332 hdr[7] = pn[0]; 333 } 334 335 336 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr) 337 { 338 pn[0] = hdr[7]; 339 pn[1] = hdr[6]; 340 pn[2] = hdr[5]; 341 pn[3] = hdr[4]; 342 pn[4] = hdr[1]; 343 pn[5] = hdr[0]; 344 } 345 346 347 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) 348 { 349 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 350 struct ieee80211_key *key = tx->key; 351 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 352 int hdrlen, len, tail; 353 u8 *pos, *pn; 354 int i; 355 356 if (info->control.hw_key && 357 !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) { 358 /* 359 * hwaccel has no need for preallocated room for CCMP 360 * header or MIC fields 361 */ 362 return 0; 363 } 364 365 hdrlen = ieee80211_hdrlen(hdr->frame_control); 366 len = skb->len - hdrlen; 367 368 if (info->control.hw_key) 369 tail = 0; 370 else 371 tail = CCMP_MIC_LEN; 372 373 if (WARN_ON(skb_tailroom(skb) < tail || 374 skb_headroom(skb) < CCMP_HDR_LEN)) 375 return -1; 376 377 pos = skb_push(skb, CCMP_HDR_LEN); 378 memmove(pos, pos + CCMP_HDR_LEN, hdrlen); 379 hdr = (struct ieee80211_hdr *) pos; 380 pos += hdrlen; 381 382 /* PN = PN + 1 */ 383 pn = key->u.ccmp.tx_pn; 384 385 for (i = CCMP_PN_LEN - 1; i >= 0; i--) { 386 pn[i]++; 387 if (pn[i]) 388 break; 389 } 390 391 ccmp_pn2hdr(pos, pn, key->conf.keyidx); 392 393 /* hwaccel - with software CCMP header */ 394 if (info->control.hw_key) 395 return 0; 396 397 pos += CCMP_HDR_LEN; 398 ccmp_special_blocks(skb, pn, key->u.ccmp.tx_crypto_buf, 0); 399 ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, key->u.ccmp.tx_crypto_buf, pos, len, 400 pos, skb_put(skb, CCMP_MIC_LEN)); 401 402 return 0; 403 } 404 405 406 ieee80211_tx_result 407 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx) 408 { 409 struct sk_buff *skb = tx->skb; 410 411 ieee80211_tx_set_protected(tx); 412 413 do { 414 if (ccmp_encrypt_skb(tx, skb) < 0) 415 return TX_DROP; 416 } while ((skb = skb->next)); 417 418 return TX_CONTINUE; 419 } 420 421 422 ieee80211_rx_result 423 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx) 424 { 425 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data; 426 int hdrlen; 427 struct ieee80211_key *key = rx->key; 428 struct sk_buff *skb = rx->skb; 429 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 430 u8 pn[CCMP_PN_LEN]; 431 int data_len; 432 int queue; 433 434 hdrlen = ieee80211_hdrlen(hdr->frame_control); 435 436 if (!ieee80211_is_data(hdr->frame_control) && 437 !ieee80211_is_robust_mgmt_frame(hdr)) 438 return RX_CONTINUE; 439 440 data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN; 441 if (!rx->sta || data_len < 0) 442 return RX_DROP_UNUSABLE; 443 444 ccmp_hdr2pn(pn, skb->data + hdrlen); 445 446 queue = ieee80211_is_mgmt(hdr->frame_control) ? 447 NUM_RX_DATA_QUEUES : rx->queue; 448 449 if (memcmp(pn, key->u.ccmp.rx_pn[queue], CCMP_PN_LEN) <= 0) { 450 key->u.ccmp.replays++; 451 return RX_DROP_UNUSABLE; 452 } 453 454 if (!(status->flag & RX_FLAG_DECRYPTED)) { 455 /* hardware didn't decrypt/verify MIC */ 456 ccmp_special_blocks(skb, pn, key->u.ccmp.rx_crypto_buf, 1); 457 458 if (ieee80211_aes_ccm_decrypt( 459 key->u.ccmp.tfm, key->u.ccmp.rx_crypto_buf, 460 skb->data + hdrlen + CCMP_HDR_LEN, data_len, 461 skb->data + skb->len - CCMP_MIC_LEN, 462 skb->data + hdrlen + CCMP_HDR_LEN)) 463 return RX_DROP_UNUSABLE; 464 } 465 466 memcpy(key->u.ccmp.rx_pn[queue], pn, CCMP_PN_LEN); 467 468 /* Remove CCMP header and MIC */ 469 skb_trim(skb, skb->len - CCMP_MIC_LEN); 470 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen); 471 skb_pull(skb, CCMP_HDR_LEN); 472 473 return RX_CONTINUE; 474 } 475 476 477 static void bip_aad(struct sk_buff *skb, u8 *aad) 478 { 479 /* BIP AAD: FC(masked) || A1 || A2 || A3 */ 480 481 /* FC type/subtype */ 482 aad[0] = skb->data[0]; 483 /* Mask FC Retry, PwrMgt, MoreData flags to zero */ 484 aad[1] = skb->data[1] & ~(BIT(4) | BIT(5) | BIT(6)); 485 /* A1 || A2 || A3 */ 486 memcpy(aad + 2, skb->data + 4, 3 * ETH_ALEN); 487 } 488 489 490 static inline void bip_ipn_swap(u8 *d, const u8 *s) 491 { 492 *d++ = s[5]; 493 *d++ = s[4]; 494 *d++ = s[3]; 495 *d++ = s[2]; 496 *d++ = s[1]; 497 *d = s[0]; 498 } 499 500 501 ieee80211_tx_result 502 ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx) 503 { 504 struct sk_buff *skb = tx->skb; 505 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 506 struct ieee80211_key *key = tx->key; 507 struct ieee80211_mmie *mmie; 508 u8 *pn, aad[20]; 509 int i; 510 511 if (info->control.hw_key) 512 return 0; 513 514 if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie))) 515 return TX_DROP; 516 517 mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie)); 518 mmie->element_id = WLAN_EID_MMIE; 519 mmie->length = sizeof(*mmie) - 2; 520 mmie->key_id = cpu_to_le16(key->conf.keyidx); 521 522 /* PN = PN + 1 */ 523 pn = key->u.aes_cmac.tx_pn; 524 525 for (i = sizeof(key->u.aes_cmac.tx_pn) - 1; i >= 0; i--) { 526 pn[i]++; 527 if (pn[i]) 528 break; 529 } 530 bip_ipn_swap(mmie->sequence_number, pn); 531 532 bip_aad(skb, aad); 533 534 /* 535 * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64) 536 */ 537 ieee80211_aes_cmac(key->u.aes_cmac.tfm, key->u.aes_cmac.tx_crypto_buf, 538 aad, skb->data + 24, skb->len - 24, mmie->mic); 539 540 return TX_CONTINUE; 541 } 542 543 544 ieee80211_rx_result 545 ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx) 546 { 547 struct sk_buff *skb = rx->skb; 548 struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); 549 struct ieee80211_key *key = rx->key; 550 struct ieee80211_mmie *mmie; 551 u8 aad[20], mic[8], ipn[6]; 552 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 553 554 if (!ieee80211_is_mgmt(hdr->frame_control)) 555 return RX_CONTINUE; 556 557 if (skb->len < 24 + sizeof(*mmie)) 558 return RX_DROP_UNUSABLE; 559 560 mmie = (struct ieee80211_mmie *) 561 (skb->data + skb->len - sizeof(*mmie)); 562 if (mmie->element_id != WLAN_EID_MMIE || 563 mmie->length != sizeof(*mmie) - 2) 564 return RX_DROP_UNUSABLE; /* Invalid MMIE */ 565 566 bip_ipn_swap(ipn, mmie->sequence_number); 567 568 if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) { 569 key->u.aes_cmac.replays++; 570 return RX_DROP_UNUSABLE; 571 } 572 573 if (!(status->flag & RX_FLAG_DECRYPTED)) { 574 /* hardware didn't decrypt/verify MIC */ 575 bip_aad(skb, aad); 576 ieee80211_aes_cmac(key->u.aes_cmac.tfm, 577 key->u.aes_cmac.rx_crypto_buf, aad, 578 skb->data + 24, skb->len - 24, mic); 579 if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) { 580 key->u.aes_cmac.icverrors++; 581 return RX_DROP_UNUSABLE; 582 } 583 } 584 585 memcpy(key->u.aes_cmac.rx_pn, ipn, 6); 586 587 /* Remove MMIE */ 588 skb_trim(skb, skb->len - sizeof(*mmie)); 589 590 return RX_CONTINUE; 591 } 592