1 /* 2 * Copyright (C) 2010 IBM Corporation 3 * Copyright (C) 2010 Politecnico di Torino, Italy 4 * TORSEC group -- http://security.polito.it 5 * 6 * Authors: 7 * Mimi Zohar <zohar@us.ibm.com> 8 * Roberto Sassu <roberto.sassu@polito.it> 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License as published by 12 * the Free Software Foundation, version 2 of the License. 13 * 14 * See Documentation/security/keys-trusted-encrypted.txt 15 */ 16 17 #include <linux/uaccess.h> 18 #include <linux/module.h> 19 #include <linux/init.h> 20 #include <linux/slab.h> 21 #include <linux/parser.h> 22 #include <linux/string.h> 23 #include <linux/err.h> 24 #include <keys/user-type.h> 25 #include <keys/trusted-type.h> 26 #include <keys/encrypted-type.h> 27 #include <linux/key-type.h> 28 #include <linux/random.h> 29 #include <linux/rcupdate.h> 30 #include <linux/scatterlist.h> 31 #include <linux/ctype.h> 32 #include <crypto/hash.h> 33 #include <crypto/sha.h> 34 #include <crypto/skcipher.h> 35 36 #include "encrypted.h" 37 #include "ecryptfs_format.h" 38 39 static const char KEY_TRUSTED_PREFIX[] = "trusted:"; 40 static const char KEY_USER_PREFIX[] = "user:"; 41 static const char hash_alg[] = "sha256"; 42 static const char hmac_alg[] = "hmac(sha256)"; 43 static const char blkcipher_alg[] = "cbc(aes)"; 44 static const char key_format_default[] = "default"; 45 static const char key_format_ecryptfs[] = "ecryptfs"; 46 static unsigned int ivsize; 47 static int blksize; 48 49 #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) 50 #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) 51 #define KEY_ECRYPTFS_DESC_LEN 16 52 #define HASH_SIZE SHA256_DIGEST_SIZE 53 #define MAX_DATA_SIZE 4096 54 #define MIN_DATA_SIZE 20 55 56 struct sdesc { 57 struct shash_desc shash; 58 char ctx[]; 59 }; 60 61 static struct crypto_shash *hashalg; 62 static struct crypto_shash *hmacalg; 63 64 enum { 65 Opt_err = -1, Opt_new, Opt_load, Opt_update 66 }; 67 68 enum { 69 Opt_error = -1, Opt_default, Opt_ecryptfs 70 }; 71 72 static const match_table_t key_format_tokens = { 73 {Opt_default, "default"}, 74 {Opt_ecryptfs, "ecryptfs"}, 75 {Opt_error, NULL} 76 }; 77 78 static const match_table_t key_tokens = { 79 {Opt_new, "new"}, 80 {Opt_load, "load"}, 81 {Opt_update, "update"}, 82 {Opt_err, NULL} 83 }; 84 85 static int aes_get_sizes(void) 86 { 87 struct crypto_skcipher *tfm; 88 89 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 90 if (IS_ERR(tfm)) { 91 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n", 92 PTR_ERR(tfm)); 93 return PTR_ERR(tfm); 94 } 95 ivsize = crypto_skcipher_ivsize(tfm); 96 blksize = crypto_skcipher_blocksize(tfm); 97 crypto_free_skcipher(tfm); 98 return 0; 99 } 100 101 /* 102 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key 103 * 104 * The description of a encrypted key with format 'ecryptfs' must contain 105 * exactly 16 hexadecimal characters. 106 * 107 */ 108 static int valid_ecryptfs_desc(const char *ecryptfs_desc) 109 { 110 int i; 111 112 if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) { 113 pr_err("encrypted_key: key description must be %d hexadecimal " 114 "characters long\n", KEY_ECRYPTFS_DESC_LEN); 115 return -EINVAL; 116 } 117 118 for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) { 119 if (!isxdigit(ecryptfs_desc[i])) { 120 pr_err("encrypted_key: key description must contain " 121 "only hexadecimal characters\n"); 122 return -EINVAL; 123 } 124 } 125 126 return 0; 127 } 128 129 /* 130 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key 131 * 132 * key-type:= "trusted:" | "user:" 133 * desc:= master-key description 134 * 135 * Verify that 'key-type' is valid and that 'desc' exists. On key update, 136 * only the master key description is permitted to change, not the key-type. 137 * The key-type remains constant. 138 * 139 * On success returns 0, otherwise -EINVAL. 140 */ 141 static int valid_master_desc(const char *new_desc, const char *orig_desc) 142 { 143 if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) { 144 if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN) 145 goto out; 146 if (orig_desc) 147 if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN)) 148 goto out; 149 } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) { 150 if (strlen(new_desc) == KEY_USER_PREFIX_LEN) 151 goto out; 152 if (orig_desc) 153 if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN)) 154 goto out; 155 } else 156 goto out; 157 return 0; 158 out: 159 return -EINVAL; 160 } 161 162 /* 163 * datablob_parse - parse the keyctl data 164 * 165 * datablob format: 166 * new [<format>] <master-key name> <decrypted data length> 167 * load [<format>] <master-key name> <decrypted data length> 168 * <encrypted iv + data> 169 * update <new-master-key name> 170 * 171 * Tokenizes a copy of the keyctl data, returning a pointer to each token, 172 * which is null terminated. 173 * 174 * On success returns 0, otherwise -EINVAL. 175 */ 176 static int datablob_parse(char *datablob, const char **format, 177 char **master_desc, char **decrypted_datalen, 178 char **hex_encoded_iv) 179 { 180 substring_t args[MAX_OPT_ARGS]; 181 int ret = -EINVAL; 182 int key_cmd; 183 int key_format; 184 char *p, *keyword; 185 186 keyword = strsep(&datablob, " \t"); 187 if (!keyword) { 188 pr_info("encrypted_key: insufficient parameters specified\n"); 189 return ret; 190 } 191 key_cmd = match_token(keyword, key_tokens, args); 192 193 /* Get optional format: default | ecryptfs */ 194 p = strsep(&datablob, " \t"); 195 if (!p) { 196 pr_err("encrypted_key: insufficient parameters specified\n"); 197 return ret; 198 } 199 200 key_format = match_token(p, key_format_tokens, args); 201 switch (key_format) { 202 case Opt_ecryptfs: 203 case Opt_default: 204 *format = p; 205 *master_desc = strsep(&datablob, " \t"); 206 break; 207 case Opt_error: 208 *master_desc = p; 209 break; 210 } 211 212 if (!*master_desc) { 213 pr_info("encrypted_key: master key parameter is missing\n"); 214 goto out; 215 } 216 217 if (valid_master_desc(*master_desc, NULL) < 0) { 218 pr_info("encrypted_key: master key parameter \'%s\' " 219 "is invalid\n", *master_desc); 220 goto out; 221 } 222 223 if (decrypted_datalen) { 224 *decrypted_datalen = strsep(&datablob, " \t"); 225 if (!*decrypted_datalen) { 226 pr_info("encrypted_key: keylen parameter is missing\n"); 227 goto out; 228 } 229 } 230 231 switch (key_cmd) { 232 case Opt_new: 233 if (!decrypted_datalen) { 234 pr_info("encrypted_key: keyword \'%s\' not allowed " 235 "when called from .update method\n", keyword); 236 break; 237 } 238 ret = 0; 239 break; 240 case Opt_load: 241 if (!decrypted_datalen) { 242 pr_info("encrypted_key: keyword \'%s\' not allowed " 243 "when called from .update method\n", keyword); 244 break; 245 } 246 *hex_encoded_iv = strsep(&datablob, " \t"); 247 if (!*hex_encoded_iv) { 248 pr_info("encrypted_key: hex blob is missing\n"); 249 break; 250 } 251 ret = 0; 252 break; 253 case Opt_update: 254 if (decrypted_datalen) { 255 pr_info("encrypted_key: keyword \'%s\' not allowed " 256 "when called from .instantiate method\n", 257 keyword); 258 break; 259 } 260 ret = 0; 261 break; 262 case Opt_err: 263 pr_info("encrypted_key: keyword \'%s\' not recognized\n", 264 keyword); 265 break; 266 } 267 out: 268 return ret; 269 } 270 271 /* 272 * datablob_format - format as an ascii string, before copying to userspace 273 */ 274 static char *datablob_format(struct encrypted_key_payload *epayload, 275 size_t asciiblob_len) 276 { 277 char *ascii_buf, *bufp; 278 u8 *iv = epayload->iv; 279 int len; 280 int i; 281 282 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); 283 if (!ascii_buf) 284 goto out; 285 286 ascii_buf[asciiblob_len] = '\0'; 287 288 /* copy datablob master_desc and datalen strings */ 289 len = sprintf(ascii_buf, "%s %s %s ", epayload->format, 290 epayload->master_desc, epayload->datalen); 291 292 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ 293 bufp = &ascii_buf[len]; 294 for (i = 0; i < (asciiblob_len - len) / 2; i++) 295 bufp = hex_byte_pack(bufp, iv[i]); 296 out: 297 return ascii_buf; 298 } 299 300 /* 301 * request_user_key - request the user key 302 * 303 * Use a user provided key to encrypt/decrypt an encrypted-key. 304 */ 305 static struct key *request_user_key(const char *master_desc, const u8 **master_key, 306 size_t *master_keylen) 307 { 308 const struct user_key_payload *upayload; 309 struct key *ukey; 310 311 ukey = request_key(&key_type_user, master_desc, NULL); 312 if (IS_ERR(ukey)) 313 goto error; 314 315 down_read(&ukey->sem); 316 upayload = user_key_payload(ukey); 317 *master_key = upayload->data; 318 *master_keylen = upayload->datalen; 319 error: 320 return ukey; 321 } 322 323 static struct sdesc *alloc_sdesc(struct crypto_shash *alg) 324 { 325 struct sdesc *sdesc; 326 int size; 327 328 size = sizeof(struct shash_desc) + crypto_shash_descsize(alg); 329 sdesc = kmalloc(size, GFP_KERNEL); 330 if (!sdesc) 331 return ERR_PTR(-ENOMEM); 332 sdesc->shash.tfm = alg; 333 sdesc->shash.flags = 0x0; 334 return sdesc; 335 } 336 337 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, 338 const u8 *buf, unsigned int buflen) 339 { 340 struct sdesc *sdesc; 341 int ret; 342 343 sdesc = alloc_sdesc(hmacalg); 344 if (IS_ERR(sdesc)) { 345 pr_info("encrypted_key: can't alloc %s\n", hmac_alg); 346 return PTR_ERR(sdesc); 347 } 348 349 ret = crypto_shash_setkey(hmacalg, key, keylen); 350 if (!ret) 351 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); 352 kfree(sdesc); 353 return ret; 354 } 355 356 static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen) 357 { 358 struct sdesc *sdesc; 359 int ret; 360 361 sdesc = alloc_sdesc(hashalg); 362 if (IS_ERR(sdesc)) { 363 pr_info("encrypted_key: can't alloc %s\n", hash_alg); 364 return PTR_ERR(sdesc); 365 } 366 367 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); 368 kfree(sdesc); 369 return ret; 370 } 371 372 enum derived_key_type { ENC_KEY, AUTH_KEY }; 373 374 /* Derive authentication/encryption key from trusted key */ 375 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, 376 const u8 *master_key, size_t master_keylen) 377 { 378 u8 *derived_buf; 379 unsigned int derived_buf_len; 380 int ret; 381 382 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; 383 if (derived_buf_len < HASH_SIZE) 384 derived_buf_len = HASH_SIZE; 385 386 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); 387 if (!derived_buf) { 388 pr_err("encrypted_key: out of memory\n"); 389 return -ENOMEM; 390 } 391 if (key_type) 392 strcpy(derived_buf, "AUTH_KEY"); 393 else 394 strcpy(derived_buf, "ENC_KEY"); 395 396 memcpy(derived_buf + strlen(derived_buf) + 1, master_key, 397 master_keylen); 398 ret = calc_hash(derived_key, derived_buf, derived_buf_len); 399 kfree(derived_buf); 400 return ret; 401 } 402 403 static struct skcipher_request *init_skcipher_req(const u8 *key, 404 unsigned int key_len) 405 { 406 struct skcipher_request *req; 407 struct crypto_skcipher *tfm; 408 int ret; 409 410 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 411 if (IS_ERR(tfm)) { 412 pr_err("encrypted_key: failed to load %s transform (%ld)\n", 413 blkcipher_alg, PTR_ERR(tfm)); 414 return ERR_CAST(tfm); 415 } 416 417 ret = crypto_skcipher_setkey(tfm, key, key_len); 418 if (ret < 0) { 419 pr_err("encrypted_key: failed to setkey (%d)\n", ret); 420 crypto_free_skcipher(tfm); 421 return ERR_PTR(ret); 422 } 423 424 req = skcipher_request_alloc(tfm, GFP_KERNEL); 425 if (!req) { 426 pr_err("encrypted_key: failed to allocate request for %s\n", 427 blkcipher_alg); 428 crypto_free_skcipher(tfm); 429 return ERR_PTR(-ENOMEM); 430 } 431 432 skcipher_request_set_callback(req, 0, NULL, NULL); 433 return req; 434 } 435 436 static struct key *request_master_key(struct encrypted_key_payload *epayload, 437 const u8 **master_key, size_t *master_keylen) 438 { 439 struct key *mkey = NULL; 440 441 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, 442 KEY_TRUSTED_PREFIX_LEN)) { 443 mkey = request_trusted_key(epayload->master_desc + 444 KEY_TRUSTED_PREFIX_LEN, 445 master_key, master_keylen); 446 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, 447 KEY_USER_PREFIX_LEN)) { 448 mkey = request_user_key(epayload->master_desc + 449 KEY_USER_PREFIX_LEN, 450 master_key, master_keylen); 451 } else 452 goto out; 453 454 if (IS_ERR(mkey)) { 455 int ret = PTR_ERR(mkey); 456 457 if (ret == -ENOTSUPP) 458 pr_info("encrypted_key: key %s not supported", 459 epayload->master_desc); 460 else 461 pr_info("encrypted_key: key %s not found", 462 epayload->master_desc); 463 goto out; 464 } 465 466 dump_master_key(*master_key, *master_keylen); 467 out: 468 return mkey; 469 } 470 471 /* Before returning data to userspace, encrypt decrypted data. */ 472 static int derived_key_encrypt(struct encrypted_key_payload *epayload, 473 const u8 *derived_key, 474 unsigned int derived_keylen) 475 { 476 struct scatterlist sg_in[2]; 477 struct scatterlist sg_out[1]; 478 struct crypto_skcipher *tfm; 479 struct skcipher_request *req; 480 unsigned int encrypted_datalen; 481 unsigned int padlen; 482 char pad[16]; 483 int ret; 484 485 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 486 padlen = encrypted_datalen - epayload->decrypted_datalen; 487 488 req = init_skcipher_req(derived_key, derived_keylen); 489 ret = PTR_ERR(req); 490 if (IS_ERR(req)) 491 goto out; 492 dump_decrypted_data(epayload); 493 494 memset(pad, 0, sizeof pad); 495 sg_init_table(sg_in, 2); 496 sg_set_buf(&sg_in[0], epayload->decrypted_data, 497 epayload->decrypted_datalen); 498 sg_set_buf(&sg_in[1], pad, padlen); 499 500 sg_init_table(sg_out, 1); 501 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); 502 503 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, 504 epayload->iv); 505 ret = crypto_skcipher_encrypt(req); 506 tfm = crypto_skcipher_reqtfm(req); 507 skcipher_request_free(req); 508 crypto_free_skcipher(tfm); 509 if (ret < 0) 510 pr_err("encrypted_key: failed to encrypt (%d)\n", ret); 511 else 512 dump_encrypted_data(epayload, encrypted_datalen); 513 out: 514 return ret; 515 } 516 517 static int datablob_hmac_append(struct encrypted_key_payload *epayload, 518 const u8 *master_key, size_t master_keylen) 519 { 520 u8 derived_key[HASH_SIZE]; 521 u8 *digest; 522 int ret; 523 524 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 525 if (ret < 0) 526 goto out; 527 528 digest = epayload->format + epayload->datablob_len; 529 ret = calc_hmac(digest, derived_key, sizeof derived_key, 530 epayload->format, epayload->datablob_len); 531 if (!ret) 532 dump_hmac(NULL, digest, HASH_SIZE); 533 out: 534 return ret; 535 } 536 537 /* verify HMAC before decrypting encrypted key */ 538 static int datablob_hmac_verify(struct encrypted_key_payload *epayload, 539 const u8 *format, const u8 *master_key, 540 size_t master_keylen) 541 { 542 u8 derived_key[HASH_SIZE]; 543 u8 digest[HASH_SIZE]; 544 int ret; 545 char *p; 546 unsigned short len; 547 548 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 549 if (ret < 0) 550 goto out; 551 552 len = epayload->datablob_len; 553 if (!format) { 554 p = epayload->master_desc; 555 len -= strlen(epayload->format) + 1; 556 } else 557 p = epayload->format; 558 559 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); 560 if (ret < 0) 561 goto out; 562 ret = memcmp(digest, epayload->format + epayload->datablob_len, 563 sizeof digest); 564 if (ret) { 565 ret = -EINVAL; 566 dump_hmac("datablob", 567 epayload->format + epayload->datablob_len, 568 HASH_SIZE); 569 dump_hmac("calc", digest, HASH_SIZE); 570 } 571 out: 572 return ret; 573 } 574 575 static int derived_key_decrypt(struct encrypted_key_payload *epayload, 576 const u8 *derived_key, 577 unsigned int derived_keylen) 578 { 579 struct scatterlist sg_in[1]; 580 struct scatterlist sg_out[2]; 581 struct crypto_skcipher *tfm; 582 struct skcipher_request *req; 583 unsigned int encrypted_datalen; 584 char pad[16]; 585 int ret; 586 587 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 588 req = init_skcipher_req(derived_key, derived_keylen); 589 ret = PTR_ERR(req); 590 if (IS_ERR(req)) 591 goto out; 592 dump_encrypted_data(epayload, encrypted_datalen); 593 594 memset(pad, 0, sizeof pad); 595 sg_init_table(sg_in, 1); 596 sg_init_table(sg_out, 2); 597 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); 598 sg_set_buf(&sg_out[0], epayload->decrypted_data, 599 epayload->decrypted_datalen); 600 sg_set_buf(&sg_out[1], pad, sizeof pad); 601 602 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, 603 epayload->iv); 604 ret = crypto_skcipher_decrypt(req); 605 tfm = crypto_skcipher_reqtfm(req); 606 skcipher_request_free(req); 607 crypto_free_skcipher(tfm); 608 if (ret < 0) 609 goto out; 610 dump_decrypted_data(epayload); 611 out: 612 return ret; 613 } 614 615 /* Allocate memory for decrypted key and datablob. */ 616 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, 617 const char *format, 618 const char *master_desc, 619 const char *datalen) 620 { 621 struct encrypted_key_payload *epayload = NULL; 622 unsigned short datablob_len; 623 unsigned short decrypted_datalen; 624 unsigned short payload_datalen; 625 unsigned int encrypted_datalen; 626 unsigned int format_len; 627 long dlen; 628 int ret; 629 630 ret = kstrtol(datalen, 10, &dlen); 631 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) 632 return ERR_PTR(-EINVAL); 633 634 format_len = (!format) ? strlen(key_format_default) : strlen(format); 635 decrypted_datalen = dlen; 636 payload_datalen = decrypted_datalen; 637 if (format && !strcmp(format, key_format_ecryptfs)) { 638 if (dlen != ECRYPTFS_MAX_KEY_BYTES) { 639 pr_err("encrypted_key: keylen for the ecryptfs format " 640 "must be equal to %d bytes\n", 641 ECRYPTFS_MAX_KEY_BYTES); 642 return ERR_PTR(-EINVAL); 643 } 644 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; 645 payload_datalen = sizeof(struct ecryptfs_auth_tok); 646 } 647 648 encrypted_datalen = roundup(decrypted_datalen, blksize); 649 650 datablob_len = format_len + 1 + strlen(master_desc) + 1 651 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; 652 653 ret = key_payload_reserve(key, payload_datalen + datablob_len 654 + HASH_SIZE + 1); 655 if (ret < 0) 656 return ERR_PTR(ret); 657 658 epayload = kzalloc(sizeof(*epayload) + payload_datalen + 659 datablob_len + HASH_SIZE + 1, GFP_KERNEL); 660 if (!epayload) 661 return ERR_PTR(-ENOMEM); 662 663 epayload->payload_datalen = payload_datalen; 664 epayload->decrypted_datalen = decrypted_datalen; 665 epayload->datablob_len = datablob_len; 666 return epayload; 667 } 668 669 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, 670 const char *format, const char *hex_encoded_iv) 671 { 672 struct key *mkey; 673 u8 derived_key[HASH_SIZE]; 674 const u8 *master_key; 675 u8 *hmac; 676 const char *hex_encoded_data; 677 unsigned int encrypted_datalen; 678 size_t master_keylen; 679 size_t asciilen; 680 int ret; 681 682 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 683 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; 684 if (strlen(hex_encoded_iv) != asciilen) 685 return -EINVAL; 686 687 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; 688 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); 689 if (ret < 0) 690 return -EINVAL; 691 ret = hex2bin(epayload->encrypted_data, hex_encoded_data, 692 encrypted_datalen); 693 if (ret < 0) 694 return -EINVAL; 695 696 hmac = epayload->format + epayload->datablob_len; 697 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), 698 HASH_SIZE); 699 if (ret < 0) 700 return -EINVAL; 701 702 mkey = request_master_key(epayload, &master_key, &master_keylen); 703 if (IS_ERR(mkey)) 704 return PTR_ERR(mkey); 705 706 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); 707 if (ret < 0) { 708 pr_err("encrypted_key: bad hmac (%d)\n", ret); 709 goto out; 710 } 711 712 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 713 if (ret < 0) 714 goto out; 715 716 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); 717 if (ret < 0) 718 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); 719 out: 720 up_read(&mkey->sem); 721 key_put(mkey); 722 return ret; 723 } 724 725 static void __ekey_init(struct encrypted_key_payload *epayload, 726 const char *format, const char *master_desc, 727 const char *datalen) 728 { 729 unsigned int format_len; 730 731 format_len = (!format) ? strlen(key_format_default) : strlen(format); 732 epayload->format = epayload->payload_data + epayload->payload_datalen; 733 epayload->master_desc = epayload->format + format_len + 1; 734 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; 735 epayload->iv = epayload->datalen + strlen(datalen) + 1; 736 epayload->encrypted_data = epayload->iv + ivsize + 1; 737 epayload->decrypted_data = epayload->payload_data; 738 739 if (!format) 740 memcpy(epayload->format, key_format_default, format_len); 741 else { 742 if (!strcmp(format, key_format_ecryptfs)) 743 epayload->decrypted_data = 744 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); 745 746 memcpy(epayload->format, format, format_len); 747 } 748 749 memcpy(epayload->master_desc, master_desc, strlen(master_desc)); 750 memcpy(epayload->datalen, datalen, strlen(datalen)); 751 } 752 753 /* 754 * encrypted_init - initialize an encrypted key 755 * 756 * For a new key, use a random number for both the iv and data 757 * itself. For an old key, decrypt the hex encoded data. 758 */ 759 static int encrypted_init(struct encrypted_key_payload *epayload, 760 const char *key_desc, const char *format, 761 const char *master_desc, const char *datalen, 762 const char *hex_encoded_iv) 763 { 764 int ret = 0; 765 766 if (format && !strcmp(format, key_format_ecryptfs)) { 767 ret = valid_ecryptfs_desc(key_desc); 768 if (ret < 0) 769 return ret; 770 771 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, 772 key_desc); 773 } 774 775 __ekey_init(epayload, format, master_desc, datalen); 776 if (!hex_encoded_iv) { 777 get_random_bytes(epayload->iv, ivsize); 778 779 get_random_bytes(epayload->decrypted_data, 780 epayload->decrypted_datalen); 781 } else 782 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); 783 return ret; 784 } 785 786 /* 787 * encrypted_instantiate - instantiate an encrypted key 788 * 789 * Decrypt an existing encrypted datablob or create a new encrypted key 790 * based on a kernel random number. 791 * 792 * On success, return 0. Otherwise return errno. 793 */ 794 static int encrypted_instantiate(struct key *key, 795 struct key_preparsed_payload *prep) 796 { 797 struct encrypted_key_payload *epayload = NULL; 798 char *datablob = NULL; 799 const char *format = NULL; 800 char *master_desc = NULL; 801 char *decrypted_datalen = NULL; 802 char *hex_encoded_iv = NULL; 803 size_t datalen = prep->datalen; 804 int ret; 805 806 if (datalen <= 0 || datalen > 32767 || !prep->data) 807 return -EINVAL; 808 809 datablob = kmalloc(datalen + 1, GFP_KERNEL); 810 if (!datablob) 811 return -ENOMEM; 812 datablob[datalen] = 0; 813 memcpy(datablob, prep->data, datalen); 814 ret = datablob_parse(datablob, &format, &master_desc, 815 &decrypted_datalen, &hex_encoded_iv); 816 if (ret < 0) 817 goto out; 818 819 epayload = encrypted_key_alloc(key, format, master_desc, 820 decrypted_datalen); 821 if (IS_ERR(epayload)) { 822 ret = PTR_ERR(epayload); 823 goto out; 824 } 825 ret = encrypted_init(epayload, key->description, format, master_desc, 826 decrypted_datalen, hex_encoded_iv); 827 if (ret < 0) { 828 kfree(epayload); 829 goto out; 830 } 831 832 rcu_assign_keypointer(key, epayload); 833 out: 834 kfree(datablob); 835 return ret; 836 } 837 838 static void encrypted_rcu_free(struct rcu_head *rcu) 839 { 840 struct encrypted_key_payload *epayload; 841 842 epayload = container_of(rcu, struct encrypted_key_payload, rcu); 843 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); 844 kfree(epayload); 845 } 846 847 /* 848 * encrypted_update - update the master key description 849 * 850 * Change the master key description for an existing encrypted key. 851 * The next read will return an encrypted datablob using the new 852 * master key description. 853 * 854 * On success, return 0. Otherwise return errno. 855 */ 856 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) 857 { 858 struct encrypted_key_payload *epayload = key->payload.data[0]; 859 struct encrypted_key_payload *new_epayload; 860 char *buf; 861 char *new_master_desc = NULL; 862 const char *format = NULL; 863 size_t datalen = prep->datalen; 864 int ret = 0; 865 866 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) 867 return -ENOKEY; 868 if (datalen <= 0 || datalen > 32767 || !prep->data) 869 return -EINVAL; 870 871 buf = kmalloc(datalen + 1, GFP_KERNEL); 872 if (!buf) 873 return -ENOMEM; 874 875 buf[datalen] = 0; 876 memcpy(buf, prep->data, datalen); 877 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); 878 if (ret < 0) 879 goto out; 880 881 ret = valid_master_desc(new_master_desc, epayload->master_desc); 882 if (ret < 0) 883 goto out; 884 885 new_epayload = encrypted_key_alloc(key, epayload->format, 886 new_master_desc, epayload->datalen); 887 if (IS_ERR(new_epayload)) { 888 ret = PTR_ERR(new_epayload); 889 goto out; 890 } 891 892 __ekey_init(new_epayload, epayload->format, new_master_desc, 893 epayload->datalen); 894 895 memcpy(new_epayload->iv, epayload->iv, ivsize); 896 memcpy(new_epayload->payload_data, epayload->payload_data, 897 epayload->payload_datalen); 898 899 rcu_assign_keypointer(key, new_epayload); 900 call_rcu(&epayload->rcu, encrypted_rcu_free); 901 out: 902 kfree(buf); 903 return ret; 904 } 905 906 /* 907 * encrypted_read - format and copy the encrypted data to userspace 908 * 909 * The resulting datablob format is: 910 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> 911 * 912 * On success, return to userspace the encrypted key datablob size. 913 */ 914 static long encrypted_read(const struct key *key, char __user *buffer, 915 size_t buflen) 916 { 917 struct encrypted_key_payload *epayload; 918 struct key *mkey; 919 const u8 *master_key; 920 size_t master_keylen; 921 char derived_key[HASH_SIZE]; 922 char *ascii_buf; 923 size_t asciiblob_len; 924 int ret; 925 926 epayload = rcu_dereference_key(key); 927 928 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ 929 asciiblob_len = epayload->datablob_len + ivsize + 1 930 + roundup(epayload->decrypted_datalen, blksize) 931 + (HASH_SIZE * 2); 932 933 if (!buffer || buflen < asciiblob_len) 934 return asciiblob_len; 935 936 mkey = request_master_key(epayload, &master_key, &master_keylen); 937 if (IS_ERR(mkey)) 938 return PTR_ERR(mkey); 939 940 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 941 if (ret < 0) 942 goto out; 943 944 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); 945 if (ret < 0) 946 goto out; 947 948 ret = datablob_hmac_append(epayload, master_key, master_keylen); 949 if (ret < 0) 950 goto out; 951 952 ascii_buf = datablob_format(epayload, asciiblob_len); 953 if (!ascii_buf) { 954 ret = -ENOMEM; 955 goto out; 956 } 957 958 up_read(&mkey->sem); 959 key_put(mkey); 960 961 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) 962 ret = -EFAULT; 963 kfree(ascii_buf); 964 965 return asciiblob_len; 966 out: 967 up_read(&mkey->sem); 968 key_put(mkey); 969 return ret; 970 } 971 972 /* 973 * encrypted_destroy - before freeing the key, clear the decrypted data 974 * 975 * Before freeing the key, clear the memory containing the decrypted 976 * key data. 977 */ 978 static void encrypted_destroy(struct key *key) 979 { 980 struct encrypted_key_payload *epayload = key->payload.data[0]; 981 982 if (!epayload) 983 return; 984 985 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); 986 kfree(key->payload.data[0]); 987 } 988 989 struct key_type key_type_encrypted = { 990 .name = "encrypted", 991 .instantiate = encrypted_instantiate, 992 .update = encrypted_update, 993 .destroy = encrypted_destroy, 994 .describe = user_describe, 995 .read = encrypted_read, 996 }; 997 EXPORT_SYMBOL_GPL(key_type_encrypted); 998 999 static void encrypted_shash_release(void) 1000 { 1001 if (hashalg) 1002 crypto_free_shash(hashalg); 1003 if (hmacalg) 1004 crypto_free_shash(hmacalg); 1005 } 1006 1007 static int __init encrypted_shash_alloc(void) 1008 { 1009 int ret; 1010 1011 hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC); 1012 if (IS_ERR(hmacalg)) { 1013 pr_info("encrypted_key: could not allocate crypto %s\n", 1014 hmac_alg); 1015 return PTR_ERR(hmacalg); 1016 } 1017 1018 hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC); 1019 if (IS_ERR(hashalg)) { 1020 pr_info("encrypted_key: could not allocate crypto %s\n", 1021 hash_alg); 1022 ret = PTR_ERR(hashalg); 1023 goto hashalg_fail; 1024 } 1025 1026 return 0; 1027 1028 hashalg_fail: 1029 crypto_free_shash(hmacalg); 1030 return ret; 1031 } 1032 1033 static int __init init_encrypted(void) 1034 { 1035 int ret; 1036 1037 ret = encrypted_shash_alloc(); 1038 if (ret < 0) 1039 return ret; 1040 ret = aes_get_sizes(); 1041 if (ret < 0) 1042 goto out; 1043 ret = register_key_type(&key_type_encrypted); 1044 if (ret < 0) 1045 goto out; 1046 return 0; 1047 out: 1048 encrypted_shash_release(); 1049 return ret; 1050 1051 } 1052 1053 static void __exit cleanup_encrypted(void) 1054 { 1055 encrypted_shash_release(); 1056 unregister_key_type(&key_type_encrypted); 1057 } 1058 1059 late_initcall(init_encrypted); 1060 module_exit(cleanup_encrypted); 1061 1062 MODULE_LICENSE("GPL"); 1063