1 /** 2 * eCryptfs: Linux filesystem encryption layer 3 * In-kernel key management code. Includes functions to parse and 4 * write authentication token-related packets with the underlying 5 * file. 6 * 7 * Copyright (C) 2004-2006 International Business Machines Corp. 8 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com> 9 * Michael C. Thompson <mcthomps@us.ibm.com> 10 * 11 * This program is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU General Public License as 13 * published by the Free Software Foundation; either version 2 of the 14 * License, or (at your option) any later version. 15 * 16 * This program is distributed in the hope that it will be useful, but 17 * WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 19 * General Public License for more details. 20 * 21 * You should have received a copy of the GNU General Public License 22 * along with this program; if not, write to the Free Software 23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 24 * 02111-1307, USA. 25 */ 26 27 #include <linux/string.h> 28 #include <linux/sched.h> 29 #include <linux/syscalls.h> 30 #include <linux/pagemap.h> 31 #include <linux/key.h> 32 #include <linux/random.h> 33 #include <linux/crypto.h> 34 #include <linux/scatterlist.h> 35 #include "ecryptfs_kernel.h" 36 37 /** 38 * request_key returned an error instead of a valid key address; 39 * determine the type of error, make appropriate log entries, and 40 * return an error code. 41 */ 42 int process_request_key_err(long err_code) 43 { 44 int rc = 0; 45 46 switch (err_code) { 47 case ENOKEY: 48 ecryptfs_printk(KERN_WARNING, "No key\n"); 49 rc = -ENOENT; 50 break; 51 case EKEYEXPIRED: 52 ecryptfs_printk(KERN_WARNING, "Key expired\n"); 53 rc = -ETIME; 54 break; 55 case EKEYREVOKED: 56 ecryptfs_printk(KERN_WARNING, "Key revoked\n"); 57 rc = -EINVAL; 58 break; 59 default: 60 ecryptfs_printk(KERN_WARNING, "Unknown error code: " 61 "[0x%.16x]\n", err_code); 62 rc = -EINVAL; 63 } 64 return rc; 65 } 66 67 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head) 68 { 69 struct list_head *walker; 70 struct ecryptfs_auth_tok_list_item *auth_tok_list_item; 71 72 walker = auth_tok_list_head->next; 73 while (walker != auth_tok_list_head) { 74 auth_tok_list_item = 75 list_entry(walker, struct ecryptfs_auth_tok_list_item, 76 list); 77 walker = auth_tok_list_item->list.next; 78 memset(auth_tok_list_item, 0, 79 sizeof(struct ecryptfs_auth_tok_list_item)); 80 kmem_cache_free(ecryptfs_auth_tok_list_item_cache, 81 auth_tok_list_item); 82 } 83 } 84 85 struct kmem_cache *ecryptfs_auth_tok_list_item_cache; 86 87 /** 88 * parse_packet_length 89 * @data: Pointer to memory containing length at offset 90 * @size: This function writes the decoded size to this memory 91 * address; zero on error 92 * @length_size: The number of bytes occupied by the encoded length 93 * 94 * Returns Zero on success 95 */ 96 static int parse_packet_length(unsigned char *data, size_t *size, 97 size_t *length_size) 98 { 99 int rc = 0; 100 101 (*length_size) = 0; 102 (*size) = 0; 103 if (data[0] < 192) { 104 /* One-byte length */ 105 (*size) = data[0]; 106 (*length_size) = 1; 107 } else if (data[0] < 224) { 108 /* Two-byte length */ 109 (*size) = ((data[0] - 192) * 256); 110 (*size) += (data[1] + 192); 111 (*length_size) = 2; 112 } else if (data[0] == 255) { 113 /* Five-byte length; we're not supposed to see this */ 114 ecryptfs_printk(KERN_ERR, "Five-byte packet length not " 115 "supported\n"); 116 rc = -EINVAL; 117 goto out; 118 } else { 119 ecryptfs_printk(KERN_ERR, "Error parsing packet length\n"); 120 rc = -EINVAL; 121 goto out; 122 } 123 out: 124 return rc; 125 } 126 127 /** 128 * write_packet_length 129 * @dest: The byte array target into which to write the 130 * length. Must have at least 5 bytes allocated. 131 * @size: The length to write. 132 * @packet_size_length: The number of bytes used to encode the 133 * packet length is written to this address. 134 * 135 * Returns zero on success; non-zero on error. 136 */ 137 static int write_packet_length(char *dest, size_t size, 138 size_t *packet_size_length) 139 { 140 int rc = 0; 141 142 if (size < 192) { 143 dest[0] = size; 144 (*packet_size_length) = 1; 145 } else if (size < 65536) { 146 dest[0] = (((size - 192) / 256) + 192); 147 dest[1] = ((size - 192) % 256); 148 (*packet_size_length) = 2; 149 } else { 150 rc = -EINVAL; 151 ecryptfs_printk(KERN_WARNING, 152 "Unsupported packet size: [%d]\n", size); 153 } 154 return rc; 155 } 156 157 /** 158 * parse_tag_3_packet 159 * @crypt_stat: The cryptographic context to modify based on packet 160 * contents. 161 * @data: The raw bytes of the packet. 162 * @auth_tok_list: eCryptfs parses packets into authentication tokens; 163 * a new authentication token will be placed at the end 164 * of this list for this packet. 165 * @new_auth_tok: Pointer to a pointer to memory that this function 166 * allocates; sets the memory address of the pointer to 167 * NULL on error. This object is added to the 168 * auth_tok_list. 169 * @packet_size: This function writes the size of the parsed packet 170 * into this memory location; zero on error. 171 * @max_packet_size: maximum number of bytes to parse 172 * 173 * Returns zero on success; non-zero on error. 174 */ 175 static int 176 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat, 177 unsigned char *data, struct list_head *auth_tok_list, 178 struct ecryptfs_auth_tok **new_auth_tok, 179 size_t *packet_size, size_t max_packet_size) 180 { 181 int rc = 0; 182 size_t body_size; 183 struct ecryptfs_auth_tok_list_item *auth_tok_list_item; 184 size_t length_size; 185 186 (*packet_size) = 0; 187 (*new_auth_tok) = NULL; 188 189 /* we check that: 190 * one byte for the Tag 3 ID flag 191 * two bytes for the body size 192 * do not exceed the maximum_packet_size 193 */ 194 if (unlikely((*packet_size) + 3 > max_packet_size)) { 195 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n"); 196 rc = -EINVAL; 197 goto out; 198 } 199 200 /* check for Tag 3 identifyer - one byte */ 201 if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) { 202 ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\n", 203 ECRYPTFS_TAG_3_PACKET_TYPE); 204 rc = -EINVAL; 205 goto out; 206 } 207 /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or 208 * at end of function upon failure */ 209 auth_tok_list_item = 210 kmem_cache_alloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL); 211 if (!auth_tok_list_item) { 212 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n"); 213 rc = -ENOMEM; 214 goto out; 215 } 216 memset(auth_tok_list_item, 0, 217 sizeof(struct ecryptfs_auth_tok_list_item)); 218 (*new_auth_tok) = &auth_tok_list_item->auth_tok; 219 220 /* check for body size - one to two bytes */ 221 rc = parse_packet_length(&data[(*packet_size)], &body_size, 222 &length_size); 223 if (rc) { 224 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; " 225 "rc = [%d]\n", rc); 226 goto out_free; 227 } 228 if (unlikely(body_size < (0x05 + ECRYPTFS_SALT_SIZE))) { 229 ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n", 230 body_size); 231 rc = -EINVAL; 232 goto out_free; 233 } 234 (*packet_size) += length_size; 235 236 /* now we know the length of the remainting Tag 3 packet size: 237 * 5 fix bytes for: version string, cipher, S2K ID, hash algo, 238 * number of hash iterations 239 * ECRYPTFS_SALT_SIZE bytes for salt 240 * body_size bytes minus the stuff above is the encrypted key size 241 */ 242 if (unlikely((*packet_size) + body_size > max_packet_size)) { 243 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n"); 244 rc = -EINVAL; 245 goto out_free; 246 } 247 248 /* There are 5 characters of additional information in the 249 * packet */ 250 (*new_auth_tok)->session_key.encrypted_key_size = 251 body_size - (0x05 + ECRYPTFS_SALT_SIZE); 252 ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n", 253 (*new_auth_tok)->session_key.encrypted_key_size); 254 255 /* Version 4 (from RFC2440) - one byte */ 256 if (unlikely(data[(*packet_size)++] != 0x04)) { 257 ecryptfs_printk(KERN_DEBUG, "Unknown version number " 258 "[%d]\n", data[(*packet_size) - 1]); 259 rc = -EINVAL; 260 goto out_free; 261 } 262 263 /* cipher - one byte */ 264 ecryptfs_cipher_code_to_string(crypt_stat->cipher, 265 (u16)data[(*packet_size)]); 266 /* A little extra work to differentiate among the AES key 267 * sizes; see RFC2440 */ 268 switch(data[(*packet_size)++]) { 269 case RFC2440_CIPHER_AES_192: 270 crypt_stat->key_size = 24; 271 break; 272 default: 273 crypt_stat->key_size = 274 (*new_auth_tok)->session_key.encrypted_key_size; 275 } 276 ecryptfs_init_crypt_ctx(crypt_stat); 277 /* S2K identifier 3 (from RFC2440) */ 278 if (unlikely(data[(*packet_size)++] != 0x03)) { 279 ecryptfs_printk(KERN_ERR, "Only S2K ID 3 is currently " 280 "supported\n"); 281 rc = -ENOSYS; 282 goto out_free; 283 } 284 285 /* TODO: finish the hash mapping */ 286 /* hash algorithm - one byte */ 287 switch (data[(*packet_size)++]) { 288 case 0x01: /* See RFC2440 for these numbers and their mappings */ 289 /* Choose MD5 */ 290 /* salt - ECRYPTFS_SALT_SIZE bytes */ 291 memcpy((*new_auth_tok)->token.password.salt, 292 &data[(*packet_size)], ECRYPTFS_SALT_SIZE); 293 (*packet_size) += ECRYPTFS_SALT_SIZE; 294 295 /* This conversion was taken straight from RFC2440 */ 296 /* number of hash iterations - one byte */ 297 (*new_auth_tok)->token.password.hash_iterations = 298 ((u32) 16 + (data[(*packet_size)] & 15)) 299 << ((data[(*packet_size)] >> 4) + 6); 300 (*packet_size)++; 301 302 /* encrypted session key - 303 * (body_size-5-ECRYPTFS_SALT_SIZE) bytes */ 304 memcpy((*new_auth_tok)->session_key.encrypted_key, 305 &data[(*packet_size)], 306 (*new_auth_tok)->session_key.encrypted_key_size); 307 (*packet_size) += 308 (*new_auth_tok)->session_key.encrypted_key_size; 309 (*new_auth_tok)->session_key.flags &= 310 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY; 311 (*new_auth_tok)->session_key.flags |= 312 ECRYPTFS_CONTAINS_ENCRYPTED_KEY; 313 (*new_auth_tok)->token.password.hash_algo = 0x01; 314 break; 315 default: 316 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: " 317 "[%d]\n", data[(*packet_size) - 1]); 318 rc = -ENOSYS; 319 goto out_free; 320 } 321 (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD; 322 /* TODO: Parametarize; we might actually want userspace to 323 * decrypt the session key. */ 324 ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags, 325 ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT); 326 ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags, 327 ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT); 328 list_add(&auth_tok_list_item->list, auth_tok_list); 329 goto out; 330 out_free: 331 (*new_auth_tok) = NULL; 332 memset(auth_tok_list_item, 0, 333 sizeof(struct ecryptfs_auth_tok_list_item)); 334 kmem_cache_free(ecryptfs_auth_tok_list_item_cache, 335 auth_tok_list_item); 336 out: 337 if (rc) 338 (*packet_size) = 0; 339 return rc; 340 } 341 342 /** 343 * parse_tag_11_packet 344 * @data: The raw bytes of the packet 345 * @contents: This function writes the data contents of the literal 346 * packet into this memory location 347 * @max_contents_bytes: The maximum number of bytes that this function 348 * is allowed to write into contents 349 * @tag_11_contents_size: This function writes the size of the parsed 350 * contents into this memory location; zero on 351 * error 352 * @packet_size: This function writes the size of the parsed packet 353 * into this memory location; zero on error 354 * @max_packet_size: maximum number of bytes to parse 355 * 356 * Returns zero on success; non-zero on error. 357 */ 358 static int 359 parse_tag_11_packet(unsigned char *data, unsigned char *contents, 360 size_t max_contents_bytes, size_t *tag_11_contents_size, 361 size_t *packet_size, size_t max_packet_size) 362 { 363 int rc = 0; 364 size_t body_size; 365 size_t length_size; 366 367 (*packet_size) = 0; 368 (*tag_11_contents_size) = 0; 369 370 /* check that: 371 * one byte for the Tag 11 ID flag 372 * two bytes for the Tag 11 length 373 * do not exceed the maximum_packet_size 374 */ 375 if (unlikely((*packet_size) + 3 > max_packet_size)) { 376 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n"); 377 rc = -EINVAL; 378 goto out; 379 } 380 381 /* check for Tag 11 identifyer - one byte */ 382 if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) { 383 ecryptfs_printk(KERN_WARNING, 384 "Invalid tag 11 packet format\n"); 385 rc = -EINVAL; 386 goto out; 387 } 388 389 /* get Tag 11 content length - one or two bytes */ 390 rc = parse_packet_length(&data[(*packet_size)], &body_size, 391 &length_size); 392 if (rc) { 393 ecryptfs_printk(KERN_WARNING, 394 "Invalid tag 11 packet format\n"); 395 goto out; 396 } 397 (*packet_size) += length_size; 398 399 if (body_size < 13) { 400 ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n", 401 body_size); 402 rc = -EINVAL; 403 goto out; 404 } 405 /* We have 13 bytes of surrounding packet values */ 406 (*tag_11_contents_size) = (body_size - 13); 407 408 /* now we know the length of the remainting Tag 11 packet size: 409 * 14 fix bytes for: special flag one, special flag two, 410 * 12 skipped bytes 411 * body_size bytes minus the stuff above is the Tag 11 content 412 */ 413 /* FIXME why is the body size one byte smaller than the actual 414 * size of the body? 415 * this seems to be an error here as well as in 416 * write_tag_11_packet() */ 417 if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) { 418 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n"); 419 rc = -EINVAL; 420 goto out; 421 } 422 423 /* special flag one - one byte */ 424 if (data[(*packet_size)++] != 0x62) { 425 ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n"); 426 rc = -EINVAL; 427 goto out; 428 } 429 430 /* special flag two - one byte */ 431 if (data[(*packet_size)++] != 0x08) { 432 ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n"); 433 rc = -EINVAL; 434 goto out; 435 } 436 437 /* skip the next 12 bytes */ 438 (*packet_size) += 12; /* We don't care about the filename or 439 * the timestamp */ 440 441 /* get the Tag 11 contents - tag_11_contents_size bytes */ 442 memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size)); 443 (*packet_size) += (*tag_11_contents_size); 444 445 out: 446 if (rc) { 447 (*packet_size) = 0; 448 (*tag_11_contents_size) = 0; 449 } 450 return rc; 451 } 452 453 /** 454 * decrypt_session_key - Decrypt the session key with the given auth_tok. 455 * 456 * Returns Zero on success; non-zero error otherwise. 457 */ 458 static int decrypt_session_key(struct ecryptfs_auth_tok *auth_tok, 459 struct ecryptfs_crypt_stat *crypt_stat) 460 { 461 struct ecryptfs_password *password_s_ptr; 462 struct scatterlist src_sg[2], dst_sg[2]; 463 struct mutex *tfm_mutex = NULL; 464 /* TODO: Use virt_to_scatterlist for these */ 465 char *encrypted_session_key; 466 char *session_key; 467 struct blkcipher_desc desc = { 468 .flags = CRYPTO_TFM_REQ_MAY_SLEEP 469 }; 470 int rc = 0; 471 472 password_s_ptr = &auth_tok->token.password; 473 if (ECRYPTFS_CHECK_FLAG(password_s_ptr->flags, 474 ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)) 475 ecryptfs_printk(KERN_DEBUG, "Session key encryption key " 476 "set; skipping key generation\n"); 477 ecryptfs_printk(KERN_DEBUG, "Session key encryption key (size [%d])" 478 ":\n", 479 password_s_ptr->session_key_encryption_key_bytes); 480 if (ecryptfs_verbosity > 0) 481 ecryptfs_dump_hex(password_s_ptr->session_key_encryption_key, 482 password_s_ptr-> 483 session_key_encryption_key_bytes); 484 if (!strcmp(crypt_stat->cipher, 485 crypt_stat->mount_crypt_stat->global_default_cipher_name) 486 && crypt_stat->mount_crypt_stat->global_key_tfm) { 487 desc.tfm = crypt_stat->mount_crypt_stat->global_key_tfm; 488 tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex; 489 } else { 490 char *full_alg_name; 491 492 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, 493 crypt_stat->cipher, 494 "ecb"); 495 if (rc) 496 goto out; 497 desc.tfm = crypto_alloc_blkcipher(full_alg_name, 0, 498 CRYPTO_ALG_ASYNC); 499 kfree(full_alg_name); 500 if (IS_ERR(desc.tfm)) { 501 rc = PTR_ERR(desc.tfm); 502 printk(KERN_ERR "Error allocating crypto context; " 503 "rc = [%d]\n", rc); 504 goto out; 505 } 506 crypto_blkcipher_set_flags(desc.tfm, CRYPTO_TFM_REQ_WEAK_KEY); 507 } 508 if (tfm_mutex) 509 mutex_lock(tfm_mutex); 510 rc = crypto_blkcipher_setkey(desc.tfm, 511 password_s_ptr->session_key_encryption_key, 512 crypt_stat->key_size); 513 if (rc < 0) { 514 printk(KERN_ERR "Error setting key for crypto context\n"); 515 rc = -EINVAL; 516 goto out_free_tfm; 517 } 518 /* TODO: virt_to_scatterlist */ 519 encrypted_session_key = (char *)__get_free_page(GFP_KERNEL); 520 if (!encrypted_session_key) { 521 ecryptfs_printk(KERN_ERR, "Out of memory\n"); 522 rc = -ENOMEM; 523 goto out_free_tfm; 524 } 525 session_key = (char *)__get_free_page(GFP_KERNEL); 526 if (!session_key) { 527 kfree(encrypted_session_key); 528 ecryptfs_printk(KERN_ERR, "Out of memory\n"); 529 rc = -ENOMEM; 530 goto out_free_tfm; 531 } 532 memcpy(encrypted_session_key, auth_tok->session_key.encrypted_key, 533 auth_tok->session_key.encrypted_key_size); 534 src_sg[0].page = virt_to_page(encrypted_session_key); 535 src_sg[0].offset = 0; 536 BUG_ON(auth_tok->session_key.encrypted_key_size > PAGE_CACHE_SIZE); 537 src_sg[0].length = auth_tok->session_key.encrypted_key_size; 538 dst_sg[0].page = virt_to_page(session_key); 539 dst_sg[0].offset = 0; 540 auth_tok->session_key.decrypted_key_size = 541 auth_tok->session_key.encrypted_key_size; 542 dst_sg[0].length = auth_tok->session_key.encrypted_key_size; 543 rc = crypto_blkcipher_decrypt(&desc, dst_sg, src_sg, 544 auth_tok->session_key.encrypted_key_size); 545 if (rc) { 546 printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc); 547 goto out_free_memory; 548 } 549 auth_tok->session_key.decrypted_key_size = 550 auth_tok->session_key.encrypted_key_size; 551 memcpy(auth_tok->session_key.decrypted_key, session_key, 552 auth_tok->session_key.decrypted_key_size); 553 auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY; 554 memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key, 555 auth_tok->session_key.decrypted_key_size); 556 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID); 557 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n"); 558 if (ecryptfs_verbosity > 0) 559 ecryptfs_dump_hex(crypt_stat->key, 560 crypt_stat->key_size); 561 out_free_memory: 562 memset(encrypted_session_key, 0, PAGE_CACHE_SIZE); 563 free_page((unsigned long)encrypted_session_key); 564 memset(session_key, 0, PAGE_CACHE_SIZE); 565 free_page((unsigned long)session_key); 566 out_free_tfm: 567 if (tfm_mutex) 568 mutex_unlock(tfm_mutex); 569 else 570 crypto_free_blkcipher(desc.tfm); 571 out: 572 return rc; 573 } 574 575 /** 576 * ecryptfs_parse_packet_set 577 * @dest: The header page in memory 578 * @version: Version of file format, to guide parsing behavior 579 * 580 * Get crypt_stat to have the file's session key if the requisite key 581 * is available to decrypt the session key. 582 * 583 * Returns Zero if a valid authentication token was retrieved and 584 * processed; negative value for file not encrypted or for error 585 * conditions. 586 */ 587 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat, 588 unsigned char *src, 589 struct dentry *ecryptfs_dentry) 590 { 591 size_t i = 0; 592 int rc = 0; 593 size_t found_auth_tok = 0; 594 size_t next_packet_is_auth_tok_packet; 595 char sig[ECRYPTFS_SIG_SIZE_HEX]; 596 struct list_head auth_tok_list; 597 struct list_head *walker; 598 struct ecryptfs_auth_tok *chosen_auth_tok = NULL; 599 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 600 &ecryptfs_superblock_to_private( 601 ecryptfs_dentry->d_sb)->mount_crypt_stat; 602 struct ecryptfs_auth_tok *candidate_auth_tok = NULL; 603 size_t packet_size; 604 struct ecryptfs_auth_tok *new_auth_tok; 605 unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE]; 606 size_t tag_11_contents_size; 607 size_t tag_11_packet_size; 608 609 INIT_LIST_HEAD(&auth_tok_list); 610 /* Parse the header to find as many packets as we can, these will be 611 * added the our &auth_tok_list */ 612 next_packet_is_auth_tok_packet = 1; 613 while (next_packet_is_auth_tok_packet) { 614 size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i); 615 616 switch (src[i]) { 617 case ECRYPTFS_TAG_3_PACKET_TYPE: 618 rc = parse_tag_3_packet(crypt_stat, 619 (unsigned char *)&src[i], 620 &auth_tok_list, &new_auth_tok, 621 &packet_size, max_packet_size); 622 if (rc) { 623 ecryptfs_printk(KERN_ERR, "Error parsing " 624 "tag 3 packet\n"); 625 rc = -EIO; 626 goto out_wipe_list; 627 } 628 i += packet_size; 629 rc = parse_tag_11_packet((unsigned char *)&src[i], 630 sig_tmp_space, 631 ECRYPTFS_SIG_SIZE, 632 &tag_11_contents_size, 633 &tag_11_packet_size, 634 max_packet_size); 635 if (rc) { 636 ecryptfs_printk(KERN_ERR, "No valid " 637 "(ecryptfs-specific) literal " 638 "packet containing " 639 "authentication token " 640 "signature found after " 641 "tag 3 packet\n"); 642 rc = -EIO; 643 goto out_wipe_list; 644 } 645 i += tag_11_packet_size; 646 if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) { 647 ecryptfs_printk(KERN_ERR, "Expected " 648 "signature of size [%d]; " 649 "read size [%d]\n", 650 ECRYPTFS_SIG_SIZE, 651 tag_11_contents_size); 652 rc = -EIO; 653 goto out_wipe_list; 654 } 655 ecryptfs_to_hex(new_auth_tok->token.password.signature, 656 sig_tmp_space, tag_11_contents_size); 657 new_auth_tok->token.password.signature[ 658 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0'; 659 ECRYPTFS_SET_FLAG(crypt_stat->flags, 660 ECRYPTFS_ENCRYPTED); 661 break; 662 case ECRYPTFS_TAG_11_PACKET_TYPE: 663 ecryptfs_printk(KERN_WARNING, "Invalid packet set " 664 "(Tag 11 not allowed by itself)\n"); 665 rc = -EIO; 666 goto out_wipe_list; 667 break; 668 default: 669 ecryptfs_printk(KERN_DEBUG, "No packet at offset " 670 "[%d] of the file header; hex value of " 671 "character is [0x%.2x]\n", i, src[i]); 672 next_packet_is_auth_tok_packet = 0; 673 } 674 } 675 if (list_empty(&auth_tok_list)) { 676 rc = -EINVAL; /* Do not support non-encrypted files in 677 * the 0.1 release */ 678 goto out; 679 } 680 /* If we have a global auth tok, then we should try to use 681 * it */ 682 if (mount_crypt_stat->global_auth_tok) { 683 memcpy(sig, mount_crypt_stat->global_auth_tok_sig, 684 ECRYPTFS_SIG_SIZE_HEX); 685 chosen_auth_tok = mount_crypt_stat->global_auth_tok; 686 } else 687 BUG(); /* We should always have a global auth tok in 688 * the 0.1 release */ 689 /* Scan list to see if our chosen_auth_tok works */ 690 list_for_each(walker, &auth_tok_list) { 691 struct ecryptfs_auth_tok_list_item *auth_tok_list_item; 692 auth_tok_list_item = 693 list_entry(walker, struct ecryptfs_auth_tok_list_item, 694 list); 695 candidate_auth_tok = &auth_tok_list_item->auth_tok; 696 if (unlikely(ecryptfs_verbosity > 0)) { 697 ecryptfs_printk(KERN_DEBUG, 698 "Considering cadidate auth tok:\n"); 699 ecryptfs_dump_auth_tok(candidate_auth_tok); 700 } 701 /* TODO: Replace ECRYPTFS_SIG_SIZE_HEX w/ dynamic value */ 702 if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD 703 && !strncmp(candidate_auth_tok->token.password.signature, 704 sig, ECRYPTFS_SIG_SIZE_HEX)) { 705 found_auth_tok = 1; 706 goto leave_list; 707 /* TODO: Transfer the common salt into the 708 * crypt_stat salt */ 709 } 710 } 711 leave_list: 712 if (!found_auth_tok) { 713 ecryptfs_printk(KERN_ERR, "Could not find authentication " 714 "token on temporary list for sig [%.*s]\n", 715 ECRYPTFS_SIG_SIZE_HEX, sig); 716 rc = -EIO; 717 goto out_wipe_list; 718 } else { 719 memcpy(&(candidate_auth_tok->token.password), 720 &(chosen_auth_tok->token.password), 721 sizeof(struct ecryptfs_password)); 722 rc = decrypt_session_key(candidate_auth_tok, crypt_stat); 723 if (rc) { 724 ecryptfs_printk(KERN_ERR, "Error decrypting the " 725 "session key\n"); 726 goto out_wipe_list; 727 } 728 rc = ecryptfs_compute_root_iv(crypt_stat); 729 if (rc) { 730 ecryptfs_printk(KERN_ERR, "Error computing " 731 "the root IV\n"); 732 goto out_wipe_list; 733 } 734 } 735 rc = ecryptfs_init_crypt_ctx(crypt_stat); 736 if (rc) { 737 ecryptfs_printk(KERN_ERR, "Error initializing crypto " 738 "context for cipher [%s]; rc = [%d]\n", 739 crypt_stat->cipher, rc); 740 } 741 out_wipe_list: 742 wipe_auth_tok_list(&auth_tok_list); 743 out: 744 return rc; 745 } 746 747 /** 748 * write_tag_11_packet 749 * @dest: Target into which Tag 11 packet is to be written 750 * @max: Maximum packet length 751 * @contents: Byte array of contents to copy in 752 * @contents_length: Number of bytes in contents 753 * @packet_length: Length of the Tag 11 packet written; zero on error 754 * 755 * Returns zero on success; non-zero on error. 756 */ 757 static int 758 write_tag_11_packet(char *dest, int max, char *contents, size_t contents_length, 759 size_t *packet_length) 760 { 761 int rc = 0; 762 size_t packet_size_length; 763 764 (*packet_length) = 0; 765 if ((13 + contents_length) > max) { 766 rc = -EINVAL; 767 ecryptfs_printk(KERN_ERR, "Packet length larger than " 768 "maximum allowable\n"); 769 goto out; 770 } 771 /* General packet header */ 772 /* Packet tag */ 773 dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE; 774 /* Packet length */ 775 rc = write_packet_length(&dest[(*packet_length)], 776 (13 + contents_length), &packet_size_length); 777 if (rc) { 778 ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet " 779 "header; cannot generate packet length\n"); 780 goto out; 781 } 782 (*packet_length) += packet_size_length; 783 /* Tag 11 specific */ 784 /* One-octet field that describes how the data is formatted */ 785 dest[(*packet_length)++] = 0x62; /* binary data */ 786 /* One-octet filename length followed by filename */ 787 dest[(*packet_length)++] = 8; 788 memcpy(&dest[(*packet_length)], "_CONSOLE", 8); 789 (*packet_length) += 8; 790 /* Four-octet number indicating modification date */ 791 memset(&dest[(*packet_length)], 0x00, 4); 792 (*packet_length) += 4; 793 /* Remainder is literal data */ 794 memcpy(&dest[(*packet_length)], contents, contents_length); 795 (*packet_length) += contents_length; 796 out: 797 if (rc) 798 (*packet_length) = 0; 799 return rc; 800 } 801 802 /** 803 * write_tag_3_packet 804 * @dest: Buffer into which to write the packet 805 * @max: Maximum number of bytes that can be written 806 * @auth_tok: Authentication token 807 * @crypt_stat: The cryptographic context 808 * @key_rec: encrypted key 809 * @packet_size: This function will write the number of bytes that end 810 * up constituting the packet; set to zero on error 811 * 812 * Returns zero on success; non-zero on error. 813 */ 814 static int 815 write_tag_3_packet(char *dest, size_t max, struct ecryptfs_auth_tok *auth_tok, 816 struct ecryptfs_crypt_stat *crypt_stat, 817 struct ecryptfs_key_record *key_rec, size_t *packet_size) 818 { 819 size_t i; 820 size_t signature_is_valid = 0; 821 size_t encrypted_session_key_valid = 0; 822 char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES]; 823 struct scatterlist dest_sg[2]; 824 struct scatterlist src_sg[2]; 825 struct mutex *tfm_mutex = NULL; 826 size_t key_rec_size; 827 size_t packet_size_length; 828 size_t cipher_code; 829 struct blkcipher_desc desc = { 830 .tfm = NULL, 831 .flags = CRYPTO_TFM_REQ_MAY_SLEEP 832 }; 833 int rc = 0; 834 835 (*packet_size) = 0; 836 /* Check for a valid signature on the auth_tok */ 837 for (i = 0; i < ECRYPTFS_SIG_SIZE_HEX; i++) 838 signature_is_valid |= auth_tok->token.password.signature[i]; 839 if (!signature_is_valid) 840 BUG(); 841 ecryptfs_from_hex((*key_rec).sig, auth_tok->token.password.signature, 842 ECRYPTFS_SIG_SIZE); 843 encrypted_session_key_valid = 0; 844 for (i = 0; i < crypt_stat->key_size; i++) 845 encrypted_session_key_valid |= 846 auth_tok->session_key.encrypted_key[i]; 847 if (encrypted_session_key_valid) { 848 memcpy((*key_rec).enc_key, 849 auth_tok->session_key.encrypted_key, 850 auth_tok->session_key.encrypted_key_size); 851 goto encrypted_session_key_set; 852 } 853 if (auth_tok->session_key.encrypted_key_size == 0) 854 auth_tok->session_key.encrypted_key_size = 855 crypt_stat->key_size; 856 if (crypt_stat->key_size == 24 857 && strcmp("aes", crypt_stat->cipher) == 0) { 858 memset((crypt_stat->key + 24), 0, 8); 859 auth_tok->session_key.encrypted_key_size = 32; 860 } 861 (*key_rec).enc_key_size = 862 auth_tok->session_key.encrypted_key_size; 863 if (ECRYPTFS_CHECK_FLAG(auth_tok->token.password.flags, 864 ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)) { 865 ecryptfs_printk(KERN_DEBUG, "Using previously generated " 866 "session key encryption key of size [%d]\n", 867 auth_tok->token.password. 868 session_key_encryption_key_bytes); 869 memcpy(session_key_encryption_key, 870 auth_tok->token.password.session_key_encryption_key, 871 crypt_stat->key_size); 872 ecryptfs_printk(KERN_DEBUG, 873 "Cached session key " "encryption key: \n"); 874 if (ecryptfs_verbosity > 0) 875 ecryptfs_dump_hex(session_key_encryption_key, 16); 876 } 877 if (unlikely(ecryptfs_verbosity > 0)) { 878 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n"); 879 ecryptfs_dump_hex(session_key_encryption_key, 16); 880 } 881 rc = virt_to_scatterlist(crypt_stat->key, 882 (*key_rec).enc_key_size, src_sg, 2); 883 if (!rc) { 884 ecryptfs_printk(KERN_ERR, "Error generating scatterlist " 885 "for crypt_stat session key\n"); 886 rc = -ENOMEM; 887 goto out; 888 } 889 rc = virt_to_scatterlist((*key_rec).enc_key, 890 (*key_rec).enc_key_size, dest_sg, 2); 891 if (!rc) { 892 ecryptfs_printk(KERN_ERR, "Error generating scatterlist " 893 "for crypt_stat encrypted session key\n"); 894 rc = -ENOMEM; 895 goto out; 896 } 897 if (!strcmp(crypt_stat->cipher, 898 crypt_stat->mount_crypt_stat->global_default_cipher_name) 899 && crypt_stat->mount_crypt_stat->global_key_tfm) { 900 desc.tfm = crypt_stat->mount_crypt_stat->global_key_tfm; 901 tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex; 902 } else { 903 char *full_alg_name; 904 905 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, 906 crypt_stat->cipher, 907 "ecb"); 908 if (rc) 909 goto out; 910 desc.tfm = crypto_alloc_blkcipher(full_alg_name, 0, 911 CRYPTO_ALG_ASYNC); 912 kfree(full_alg_name); 913 if (IS_ERR(desc.tfm)) { 914 rc = PTR_ERR(desc.tfm); 915 ecryptfs_printk(KERN_ERR, "Could not initialize crypto " 916 "context for cipher [%s]; rc = [%d]\n", 917 crypt_stat->cipher, rc); 918 goto out; 919 } 920 crypto_blkcipher_set_flags(desc.tfm, CRYPTO_TFM_REQ_WEAK_KEY); 921 } 922 if (tfm_mutex) 923 mutex_lock(tfm_mutex); 924 rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key, 925 crypt_stat->key_size); 926 if (rc < 0) { 927 if (tfm_mutex) 928 mutex_unlock(tfm_mutex); 929 ecryptfs_printk(KERN_ERR, "Error setting key for crypto " 930 "context; rc = [%d]\n", rc); 931 goto out; 932 } 933 rc = 0; 934 ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n", 935 crypt_stat->key_size); 936 rc = crypto_blkcipher_encrypt(&desc, dest_sg, src_sg, 937 (*key_rec).enc_key_size); 938 if (rc) { 939 printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc); 940 goto out; 941 } 942 if (tfm_mutex) 943 mutex_unlock(tfm_mutex); 944 ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n"); 945 if (ecryptfs_verbosity > 0) 946 ecryptfs_dump_hex((*key_rec).enc_key, 947 (*key_rec).enc_key_size); 948 encrypted_session_key_set: 949 /* Now we have a valid key_rec. Append it to the 950 * key_rec set. */ 951 key_rec_size = (sizeof(struct ecryptfs_key_record) 952 - ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES 953 + ((*key_rec).enc_key_size)); 954 /* TODO: Include a packet size limit as a parameter to this 955 * function once we have multi-packet headers (for versions 956 * later than 0.1 */ 957 if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) { 958 ecryptfs_printk(KERN_ERR, "Keyset too large\n"); 959 rc = -EINVAL; 960 goto out; 961 } 962 /* TODO: Packet size limit */ 963 /* We have 5 bytes of surrounding packet data */ 964 if ((0x05 + ECRYPTFS_SALT_SIZE 965 + (*key_rec).enc_key_size) >= max) { 966 ecryptfs_printk(KERN_ERR, "Authentication token is too " 967 "large\n"); 968 rc = -EINVAL; 969 goto out; 970 } 971 /* This format is inspired by OpenPGP; see RFC 2440 972 * packet tag 3 */ 973 dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE; 974 /* ver+cipher+s2k+hash+salt+iter+enc_key */ 975 rc = write_packet_length(&dest[(*packet_size)], 976 (0x05 + ECRYPTFS_SALT_SIZE 977 + (*key_rec).enc_key_size), 978 &packet_size_length); 979 if (rc) { 980 ecryptfs_printk(KERN_ERR, "Error generating tag 3 packet " 981 "header; cannot generate packet length\n"); 982 goto out; 983 } 984 (*packet_size) += packet_size_length; 985 dest[(*packet_size)++] = 0x04; /* version 4 */ 986 cipher_code = ecryptfs_code_for_cipher_string(crypt_stat); 987 if (cipher_code == 0) { 988 ecryptfs_printk(KERN_WARNING, "Unable to generate code for " 989 "cipher [%s]\n", crypt_stat->cipher); 990 rc = -EINVAL; 991 goto out; 992 } 993 dest[(*packet_size)++] = cipher_code; 994 dest[(*packet_size)++] = 0x03; /* S2K */ 995 dest[(*packet_size)++] = 0x01; /* MD5 (TODO: parameterize) */ 996 memcpy(&dest[(*packet_size)], auth_tok->token.password.salt, 997 ECRYPTFS_SALT_SIZE); 998 (*packet_size) += ECRYPTFS_SALT_SIZE; /* salt */ 999 dest[(*packet_size)++] = 0x60; /* hash iterations (65536) */ 1000 memcpy(&dest[(*packet_size)], (*key_rec).enc_key, 1001 (*key_rec).enc_key_size); 1002 (*packet_size) += (*key_rec).enc_key_size; 1003 out: 1004 if (desc.tfm && !tfm_mutex) 1005 crypto_free_blkcipher(desc.tfm); 1006 if (rc) 1007 (*packet_size) = 0; 1008 return rc; 1009 } 1010 1011 /** 1012 * ecryptfs_generate_key_packet_set 1013 * @dest: Virtual address from which to write the key record set 1014 * @crypt_stat: The cryptographic context from which the 1015 * authentication tokens will be retrieved 1016 * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat 1017 * for the global parameters 1018 * @len: The amount written 1019 * @max: The maximum amount of data allowed to be written 1020 * 1021 * Generates a key packet set and writes it to the virtual address 1022 * passed in. 1023 * 1024 * Returns zero on success; non-zero on error. 1025 */ 1026 int 1027 ecryptfs_generate_key_packet_set(char *dest_base, 1028 struct ecryptfs_crypt_stat *crypt_stat, 1029 struct dentry *ecryptfs_dentry, size_t *len, 1030 size_t max) 1031 { 1032 int rc = 0; 1033 struct ecryptfs_auth_tok *auth_tok; 1034 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 1035 &ecryptfs_superblock_to_private( 1036 ecryptfs_dentry->d_sb)->mount_crypt_stat; 1037 size_t written; 1038 struct ecryptfs_key_record key_rec; 1039 1040 (*len) = 0; 1041 if (mount_crypt_stat->global_auth_tok) { 1042 auth_tok = mount_crypt_stat->global_auth_tok; 1043 if (auth_tok->token_type == ECRYPTFS_PASSWORD) { 1044 rc = write_tag_3_packet((dest_base + (*len)), 1045 max, auth_tok, 1046 crypt_stat, &key_rec, 1047 &written); 1048 if (rc) { 1049 ecryptfs_printk(KERN_WARNING, "Error " 1050 "writing tag 3 packet\n"); 1051 goto out; 1052 } 1053 (*len) += written; 1054 /* Write auth tok signature packet */ 1055 rc = write_tag_11_packet( 1056 (dest_base + (*len)), 1057 (max - (*len)), 1058 key_rec.sig, ECRYPTFS_SIG_SIZE, &written); 1059 if (rc) { 1060 ecryptfs_printk(KERN_ERR, "Error writing " 1061 "auth tok signature packet\n"); 1062 goto out; 1063 } 1064 (*len) += written; 1065 } else { 1066 ecryptfs_printk(KERN_WARNING, "Unsupported " 1067 "authentication token type\n"); 1068 rc = -EINVAL; 1069 goto out; 1070 } 1071 if (rc) { 1072 ecryptfs_printk(KERN_WARNING, "Error writing " 1073 "authentication token packet with sig " 1074 "= [%s]\n", 1075 mount_crypt_stat->global_auth_tok_sig); 1076 rc = -EIO; 1077 goto out; 1078 } 1079 } else 1080 BUG(); 1081 if (likely((max - (*len)) > 0)) { 1082 dest_base[(*len)] = 0x00; 1083 } else { 1084 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n"); 1085 rc = -EIO; 1086 } 1087 out: 1088 if (rc) 1089 (*len) = 0; 1090 return rc; 1091 } 1092