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/aes.h> 33 #include <crypto/hash.h> 34 #include <crypto/sha.h> 35 #include <crypto/skcipher.h> 36 37 #include "encrypted.h" 38 #include "ecryptfs_format.h" 39 40 static const char KEY_TRUSTED_PREFIX[] = "trusted:"; 41 static const char KEY_USER_PREFIX[] = "user:"; 42 static const char hash_alg[] = "sha256"; 43 static const char hmac_alg[] = "hmac(sha256)"; 44 static const char blkcipher_alg[] = "cbc(aes)"; 45 static const char key_format_default[] = "default"; 46 static const char key_format_ecryptfs[] = "ecryptfs"; 47 static unsigned int ivsize; 48 static int blksize; 49 50 #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) 51 #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) 52 #define KEY_ECRYPTFS_DESC_LEN 16 53 #define HASH_SIZE SHA256_DIGEST_SIZE 54 #define MAX_DATA_SIZE 4096 55 #define MIN_DATA_SIZE 20 56 57 struct sdesc { 58 struct shash_desc shash; 59 char ctx[]; 60 }; 61 62 static struct crypto_shash *hashalg; 63 static struct crypto_shash *hmacalg; 64 65 enum { 66 Opt_err = -1, Opt_new, Opt_load, Opt_update 67 }; 68 69 enum { 70 Opt_error = -1, Opt_default, Opt_ecryptfs 71 }; 72 73 static const match_table_t key_format_tokens = { 74 {Opt_default, "default"}, 75 {Opt_ecryptfs, "ecryptfs"}, 76 {Opt_error, NULL} 77 }; 78 79 static const match_table_t key_tokens = { 80 {Opt_new, "new"}, 81 {Opt_load, "load"}, 82 {Opt_update, "update"}, 83 {Opt_err, NULL} 84 }; 85 86 static int aes_get_sizes(void) 87 { 88 struct crypto_skcipher *tfm; 89 90 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 91 if (IS_ERR(tfm)) { 92 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n", 93 PTR_ERR(tfm)); 94 return PTR_ERR(tfm); 95 } 96 ivsize = crypto_skcipher_ivsize(tfm); 97 blksize = crypto_skcipher_blocksize(tfm); 98 crypto_free_skcipher(tfm); 99 return 0; 100 } 101 102 /* 103 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key 104 * 105 * The description of a encrypted key with format 'ecryptfs' must contain 106 * exactly 16 hexadecimal characters. 107 * 108 */ 109 static int valid_ecryptfs_desc(const char *ecryptfs_desc) 110 { 111 int i; 112 113 if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) { 114 pr_err("encrypted_key: key description must be %d hexadecimal " 115 "characters long\n", KEY_ECRYPTFS_DESC_LEN); 116 return -EINVAL; 117 } 118 119 for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) { 120 if (!isxdigit(ecryptfs_desc[i])) { 121 pr_err("encrypted_key: key description must contain " 122 "only hexadecimal characters\n"); 123 return -EINVAL; 124 } 125 } 126 127 return 0; 128 } 129 130 /* 131 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key 132 * 133 * key-type:= "trusted:" | "user:" 134 * desc:= master-key description 135 * 136 * Verify that 'key-type' is valid and that 'desc' exists. On key update, 137 * only the master key description is permitted to change, not the key-type. 138 * The key-type remains constant. 139 * 140 * On success returns 0, otherwise -EINVAL. 141 */ 142 static int valid_master_desc(const char *new_desc, const char *orig_desc) 143 { 144 if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) { 145 if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN) 146 goto out; 147 if (orig_desc) 148 if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN)) 149 goto out; 150 } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) { 151 if (strlen(new_desc) == KEY_USER_PREFIX_LEN) 152 goto out; 153 if (orig_desc) 154 if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN)) 155 goto out; 156 } else 157 goto out; 158 return 0; 159 out: 160 return -EINVAL; 161 } 162 163 /* 164 * datablob_parse - parse the keyctl data 165 * 166 * datablob format: 167 * new [<format>] <master-key name> <decrypted data length> 168 * load [<format>] <master-key name> <decrypted data length> 169 * <encrypted iv + data> 170 * update <new-master-key name> 171 * 172 * Tokenizes a copy of the keyctl data, returning a pointer to each token, 173 * which is null terminated. 174 * 175 * On success returns 0, otherwise -EINVAL. 176 */ 177 static int datablob_parse(char *datablob, const char **format, 178 char **master_desc, char **decrypted_datalen, 179 char **hex_encoded_iv) 180 { 181 substring_t args[MAX_OPT_ARGS]; 182 int ret = -EINVAL; 183 int key_cmd; 184 int key_format; 185 char *p, *keyword; 186 187 keyword = strsep(&datablob, " \t"); 188 if (!keyword) { 189 pr_info("encrypted_key: insufficient parameters specified\n"); 190 return ret; 191 } 192 key_cmd = match_token(keyword, key_tokens, args); 193 194 /* Get optional format: default | ecryptfs */ 195 p = strsep(&datablob, " \t"); 196 if (!p) { 197 pr_err("encrypted_key: insufficient parameters specified\n"); 198 return ret; 199 } 200 201 key_format = match_token(p, key_format_tokens, args); 202 switch (key_format) { 203 case Opt_ecryptfs: 204 case Opt_default: 205 *format = p; 206 *master_desc = strsep(&datablob, " \t"); 207 break; 208 case Opt_error: 209 *master_desc = p; 210 break; 211 } 212 213 if (!*master_desc) { 214 pr_info("encrypted_key: master key parameter is missing\n"); 215 goto out; 216 } 217 218 if (valid_master_desc(*master_desc, NULL) < 0) { 219 pr_info("encrypted_key: master key parameter \'%s\' " 220 "is invalid\n", *master_desc); 221 goto out; 222 } 223 224 if (decrypted_datalen) { 225 *decrypted_datalen = strsep(&datablob, " \t"); 226 if (!*decrypted_datalen) { 227 pr_info("encrypted_key: keylen parameter is missing\n"); 228 goto out; 229 } 230 } 231 232 switch (key_cmd) { 233 case Opt_new: 234 if (!decrypted_datalen) { 235 pr_info("encrypted_key: keyword \'%s\' not allowed " 236 "when called from .update method\n", keyword); 237 break; 238 } 239 ret = 0; 240 break; 241 case Opt_load: 242 if (!decrypted_datalen) { 243 pr_info("encrypted_key: keyword \'%s\' not allowed " 244 "when called from .update method\n", keyword); 245 break; 246 } 247 *hex_encoded_iv = strsep(&datablob, " \t"); 248 if (!*hex_encoded_iv) { 249 pr_info("encrypted_key: hex blob is missing\n"); 250 break; 251 } 252 ret = 0; 253 break; 254 case Opt_update: 255 if (decrypted_datalen) { 256 pr_info("encrypted_key: keyword \'%s\' not allowed " 257 "when called from .instantiate method\n", 258 keyword); 259 break; 260 } 261 ret = 0; 262 break; 263 case Opt_err: 264 pr_info("encrypted_key: keyword \'%s\' not recognized\n", 265 keyword); 266 break; 267 } 268 out: 269 return ret; 270 } 271 272 /* 273 * datablob_format - format as an ascii string, before copying to userspace 274 */ 275 static char *datablob_format(struct encrypted_key_payload *epayload, 276 size_t asciiblob_len) 277 { 278 char *ascii_buf, *bufp; 279 u8 *iv = epayload->iv; 280 int len; 281 int i; 282 283 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); 284 if (!ascii_buf) 285 goto out; 286 287 ascii_buf[asciiblob_len] = '\0'; 288 289 /* copy datablob master_desc and datalen strings */ 290 len = sprintf(ascii_buf, "%s %s %s ", epayload->format, 291 epayload->master_desc, epayload->datalen); 292 293 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ 294 bufp = &ascii_buf[len]; 295 for (i = 0; i < (asciiblob_len - len) / 2; i++) 296 bufp = hex_byte_pack(bufp, iv[i]); 297 out: 298 return ascii_buf; 299 } 300 301 /* 302 * request_user_key - request the user key 303 * 304 * Use a user provided key to encrypt/decrypt an encrypted-key. 305 */ 306 static struct key *request_user_key(const char *master_desc, const u8 **master_key, 307 size_t *master_keylen) 308 { 309 const struct user_key_payload *upayload; 310 struct key *ukey; 311 312 ukey = request_key(&key_type_user, master_desc, NULL); 313 if (IS_ERR(ukey)) 314 goto error; 315 316 down_read(&ukey->sem); 317 upayload = user_key_payload_locked(ukey); 318 *master_key = upayload->data; 319 *master_keylen = upayload->datalen; 320 error: 321 return ukey; 322 } 323 324 static struct sdesc *alloc_sdesc(struct crypto_shash *alg) 325 { 326 struct sdesc *sdesc; 327 int size; 328 329 size = sizeof(struct shash_desc) + crypto_shash_descsize(alg); 330 sdesc = kmalloc(size, GFP_KERNEL); 331 if (!sdesc) 332 return ERR_PTR(-ENOMEM); 333 sdesc->shash.tfm = alg; 334 sdesc->shash.flags = 0x0; 335 return sdesc; 336 } 337 338 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, 339 const u8 *buf, unsigned int buflen) 340 { 341 struct sdesc *sdesc; 342 int ret; 343 344 sdesc = alloc_sdesc(hmacalg); 345 if (IS_ERR(sdesc)) { 346 pr_info("encrypted_key: can't alloc %s\n", hmac_alg); 347 return PTR_ERR(sdesc); 348 } 349 350 ret = crypto_shash_setkey(hmacalg, key, keylen); 351 if (!ret) 352 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); 353 kfree(sdesc); 354 return ret; 355 } 356 357 static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen) 358 { 359 struct sdesc *sdesc; 360 int ret; 361 362 sdesc = alloc_sdesc(hashalg); 363 if (IS_ERR(sdesc)) { 364 pr_info("encrypted_key: can't alloc %s\n", hash_alg); 365 return PTR_ERR(sdesc); 366 } 367 368 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); 369 kfree(sdesc); 370 return ret; 371 } 372 373 enum derived_key_type { ENC_KEY, AUTH_KEY }; 374 375 /* Derive authentication/encryption key from trusted key */ 376 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, 377 const u8 *master_key, size_t master_keylen) 378 { 379 u8 *derived_buf; 380 unsigned int derived_buf_len; 381 int ret; 382 383 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; 384 if (derived_buf_len < HASH_SIZE) 385 derived_buf_len = HASH_SIZE; 386 387 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); 388 if (!derived_buf) { 389 pr_err("encrypted_key: out of memory\n"); 390 return -ENOMEM; 391 } 392 if (key_type) 393 strcpy(derived_buf, "AUTH_KEY"); 394 else 395 strcpy(derived_buf, "ENC_KEY"); 396 397 memcpy(derived_buf + strlen(derived_buf) + 1, master_key, 398 master_keylen); 399 ret = calc_hash(derived_key, derived_buf, derived_buf_len); 400 kfree(derived_buf); 401 return ret; 402 } 403 404 static struct skcipher_request *init_skcipher_req(const u8 *key, 405 unsigned int key_len) 406 { 407 struct skcipher_request *req; 408 struct crypto_skcipher *tfm; 409 int ret; 410 411 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 412 if (IS_ERR(tfm)) { 413 pr_err("encrypted_key: failed to load %s transform (%ld)\n", 414 blkcipher_alg, PTR_ERR(tfm)); 415 return ERR_CAST(tfm); 416 } 417 418 ret = crypto_skcipher_setkey(tfm, key, key_len); 419 if (ret < 0) { 420 pr_err("encrypted_key: failed to setkey (%d)\n", ret); 421 crypto_free_skcipher(tfm); 422 return ERR_PTR(ret); 423 } 424 425 req = skcipher_request_alloc(tfm, GFP_KERNEL); 426 if (!req) { 427 pr_err("encrypted_key: failed to allocate request for %s\n", 428 blkcipher_alg); 429 crypto_free_skcipher(tfm); 430 return ERR_PTR(-ENOMEM); 431 } 432 433 skcipher_request_set_callback(req, 0, NULL, NULL); 434 return req; 435 } 436 437 static struct key *request_master_key(struct encrypted_key_payload *epayload, 438 const u8 **master_key, size_t *master_keylen) 439 { 440 struct key *mkey = ERR_PTR(-EINVAL); 441 442 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, 443 KEY_TRUSTED_PREFIX_LEN)) { 444 mkey = request_trusted_key(epayload->master_desc + 445 KEY_TRUSTED_PREFIX_LEN, 446 master_key, master_keylen); 447 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, 448 KEY_USER_PREFIX_LEN)) { 449 mkey = request_user_key(epayload->master_desc + 450 KEY_USER_PREFIX_LEN, 451 master_key, master_keylen); 452 } else 453 goto out; 454 455 if (IS_ERR(mkey)) { 456 int ret = PTR_ERR(mkey); 457 458 if (ret == -ENOTSUPP) 459 pr_info("encrypted_key: key %s not supported", 460 epayload->master_desc); 461 else 462 pr_info("encrypted_key: key %s not found", 463 epayload->master_desc); 464 goto out; 465 } 466 467 dump_master_key(*master_key, *master_keylen); 468 out: 469 return mkey; 470 } 471 472 /* Before returning data to userspace, encrypt decrypted data. */ 473 static int derived_key_encrypt(struct encrypted_key_payload *epayload, 474 const u8 *derived_key, 475 unsigned int derived_keylen) 476 { 477 struct scatterlist sg_in[2]; 478 struct scatterlist sg_out[1]; 479 struct crypto_skcipher *tfm; 480 struct skcipher_request *req; 481 unsigned int encrypted_datalen; 482 u8 iv[AES_BLOCK_SIZE]; 483 unsigned int padlen; 484 char pad[16]; 485 int ret; 486 487 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 488 padlen = encrypted_datalen - epayload->decrypted_datalen; 489 490 req = init_skcipher_req(derived_key, derived_keylen); 491 ret = PTR_ERR(req); 492 if (IS_ERR(req)) 493 goto out; 494 dump_decrypted_data(epayload); 495 496 memset(pad, 0, sizeof pad); 497 sg_init_table(sg_in, 2); 498 sg_set_buf(&sg_in[0], epayload->decrypted_data, 499 epayload->decrypted_datalen); 500 sg_set_buf(&sg_in[1], pad, padlen); 501 502 sg_init_table(sg_out, 1); 503 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); 504 505 memcpy(iv, epayload->iv, sizeof(iv)); 506 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 507 ret = crypto_skcipher_encrypt(req); 508 tfm = crypto_skcipher_reqtfm(req); 509 skcipher_request_free(req); 510 crypto_free_skcipher(tfm); 511 if (ret < 0) 512 pr_err("encrypted_key: failed to encrypt (%d)\n", ret); 513 else 514 dump_encrypted_data(epayload, encrypted_datalen); 515 out: 516 return ret; 517 } 518 519 static int datablob_hmac_append(struct encrypted_key_payload *epayload, 520 const u8 *master_key, size_t master_keylen) 521 { 522 u8 derived_key[HASH_SIZE]; 523 u8 *digest; 524 int ret; 525 526 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 527 if (ret < 0) 528 goto out; 529 530 digest = epayload->format + epayload->datablob_len; 531 ret = calc_hmac(digest, derived_key, sizeof derived_key, 532 epayload->format, epayload->datablob_len); 533 if (!ret) 534 dump_hmac(NULL, digest, HASH_SIZE); 535 out: 536 return ret; 537 } 538 539 /* verify HMAC before decrypting encrypted key */ 540 static int datablob_hmac_verify(struct encrypted_key_payload *epayload, 541 const u8 *format, const u8 *master_key, 542 size_t master_keylen) 543 { 544 u8 derived_key[HASH_SIZE]; 545 u8 digest[HASH_SIZE]; 546 int ret; 547 char *p; 548 unsigned short len; 549 550 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 551 if (ret < 0) 552 goto out; 553 554 len = epayload->datablob_len; 555 if (!format) { 556 p = epayload->master_desc; 557 len -= strlen(epayload->format) + 1; 558 } else 559 p = epayload->format; 560 561 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); 562 if (ret < 0) 563 goto out; 564 ret = memcmp(digest, epayload->format + epayload->datablob_len, 565 sizeof digest); 566 if (ret) { 567 ret = -EINVAL; 568 dump_hmac("datablob", 569 epayload->format + epayload->datablob_len, 570 HASH_SIZE); 571 dump_hmac("calc", digest, HASH_SIZE); 572 } 573 out: 574 return ret; 575 } 576 577 static int derived_key_decrypt(struct encrypted_key_payload *epayload, 578 const u8 *derived_key, 579 unsigned int derived_keylen) 580 { 581 struct scatterlist sg_in[1]; 582 struct scatterlist sg_out[2]; 583 struct crypto_skcipher *tfm; 584 struct skcipher_request *req; 585 unsigned int encrypted_datalen; 586 u8 iv[AES_BLOCK_SIZE]; 587 char pad[16]; 588 int ret; 589 590 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 591 req = init_skcipher_req(derived_key, derived_keylen); 592 ret = PTR_ERR(req); 593 if (IS_ERR(req)) 594 goto out; 595 dump_encrypted_data(epayload, encrypted_datalen); 596 597 memset(pad, 0, sizeof pad); 598 sg_init_table(sg_in, 1); 599 sg_init_table(sg_out, 2); 600 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); 601 sg_set_buf(&sg_out[0], epayload->decrypted_data, 602 epayload->decrypted_datalen); 603 sg_set_buf(&sg_out[1], pad, sizeof pad); 604 605 memcpy(iv, epayload->iv, sizeof(iv)); 606 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 607 ret = crypto_skcipher_decrypt(req); 608 tfm = crypto_skcipher_reqtfm(req); 609 skcipher_request_free(req); 610 crypto_free_skcipher(tfm); 611 if (ret < 0) 612 goto out; 613 dump_decrypted_data(epayload); 614 out: 615 return ret; 616 } 617 618 /* Allocate memory for decrypted key and datablob. */ 619 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, 620 const char *format, 621 const char *master_desc, 622 const char *datalen) 623 { 624 struct encrypted_key_payload *epayload = NULL; 625 unsigned short datablob_len; 626 unsigned short decrypted_datalen; 627 unsigned short payload_datalen; 628 unsigned int encrypted_datalen; 629 unsigned int format_len; 630 long dlen; 631 int ret; 632 633 ret = kstrtol(datalen, 10, &dlen); 634 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) 635 return ERR_PTR(-EINVAL); 636 637 format_len = (!format) ? strlen(key_format_default) : strlen(format); 638 decrypted_datalen = dlen; 639 payload_datalen = decrypted_datalen; 640 if (format && !strcmp(format, key_format_ecryptfs)) { 641 if (dlen != ECRYPTFS_MAX_KEY_BYTES) { 642 pr_err("encrypted_key: keylen for the ecryptfs format " 643 "must be equal to %d bytes\n", 644 ECRYPTFS_MAX_KEY_BYTES); 645 return ERR_PTR(-EINVAL); 646 } 647 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; 648 payload_datalen = sizeof(struct ecryptfs_auth_tok); 649 } 650 651 encrypted_datalen = roundup(decrypted_datalen, blksize); 652 653 datablob_len = format_len + 1 + strlen(master_desc) + 1 654 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; 655 656 ret = key_payload_reserve(key, payload_datalen + datablob_len 657 + HASH_SIZE + 1); 658 if (ret < 0) 659 return ERR_PTR(ret); 660 661 epayload = kzalloc(sizeof(*epayload) + payload_datalen + 662 datablob_len + HASH_SIZE + 1, GFP_KERNEL); 663 if (!epayload) 664 return ERR_PTR(-ENOMEM); 665 666 epayload->payload_datalen = payload_datalen; 667 epayload->decrypted_datalen = decrypted_datalen; 668 epayload->datablob_len = datablob_len; 669 return epayload; 670 } 671 672 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, 673 const char *format, const char *hex_encoded_iv) 674 { 675 struct key *mkey; 676 u8 derived_key[HASH_SIZE]; 677 const u8 *master_key; 678 u8 *hmac; 679 const char *hex_encoded_data; 680 unsigned int encrypted_datalen; 681 size_t master_keylen; 682 size_t asciilen; 683 int ret; 684 685 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 686 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; 687 if (strlen(hex_encoded_iv) != asciilen) 688 return -EINVAL; 689 690 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; 691 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); 692 if (ret < 0) 693 return -EINVAL; 694 ret = hex2bin(epayload->encrypted_data, hex_encoded_data, 695 encrypted_datalen); 696 if (ret < 0) 697 return -EINVAL; 698 699 hmac = epayload->format + epayload->datablob_len; 700 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), 701 HASH_SIZE); 702 if (ret < 0) 703 return -EINVAL; 704 705 mkey = request_master_key(epayload, &master_key, &master_keylen); 706 if (IS_ERR(mkey)) 707 return PTR_ERR(mkey); 708 709 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); 710 if (ret < 0) { 711 pr_err("encrypted_key: bad hmac (%d)\n", ret); 712 goto out; 713 } 714 715 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 716 if (ret < 0) 717 goto out; 718 719 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); 720 if (ret < 0) 721 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); 722 out: 723 up_read(&mkey->sem); 724 key_put(mkey); 725 return ret; 726 } 727 728 static void __ekey_init(struct encrypted_key_payload *epayload, 729 const char *format, const char *master_desc, 730 const char *datalen) 731 { 732 unsigned int format_len; 733 734 format_len = (!format) ? strlen(key_format_default) : strlen(format); 735 epayload->format = epayload->payload_data + epayload->payload_datalen; 736 epayload->master_desc = epayload->format + format_len + 1; 737 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; 738 epayload->iv = epayload->datalen + strlen(datalen) + 1; 739 epayload->encrypted_data = epayload->iv + ivsize + 1; 740 epayload->decrypted_data = epayload->payload_data; 741 742 if (!format) 743 memcpy(epayload->format, key_format_default, format_len); 744 else { 745 if (!strcmp(format, key_format_ecryptfs)) 746 epayload->decrypted_data = 747 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); 748 749 memcpy(epayload->format, format, format_len); 750 } 751 752 memcpy(epayload->master_desc, master_desc, strlen(master_desc)); 753 memcpy(epayload->datalen, datalen, strlen(datalen)); 754 } 755 756 /* 757 * encrypted_init - initialize an encrypted key 758 * 759 * For a new key, use a random number for both the iv and data 760 * itself. For an old key, decrypt the hex encoded data. 761 */ 762 static int encrypted_init(struct encrypted_key_payload *epayload, 763 const char *key_desc, const char *format, 764 const char *master_desc, const char *datalen, 765 const char *hex_encoded_iv) 766 { 767 int ret = 0; 768 769 if (format && !strcmp(format, key_format_ecryptfs)) { 770 ret = valid_ecryptfs_desc(key_desc); 771 if (ret < 0) 772 return ret; 773 774 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, 775 key_desc); 776 } 777 778 __ekey_init(epayload, format, master_desc, datalen); 779 if (!hex_encoded_iv) { 780 get_random_bytes(epayload->iv, ivsize); 781 782 get_random_bytes(epayload->decrypted_data, 783 epayload->decrypted_datalen); 784 } else 785 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); 786 return ret; 787 } 788 789 /* 790 * encrypted_instantiate - instantiate an encrypted key 791 * 792 * Decrypt an existing encrypted datablob or create a new encrypted key 793 * based on a kernel random number. 794 * 795 * On success, return 0. Otherwise return errno. 796 */ 797 static int encrypted_instantiate(struct key *key, 798 struct key_preparsed_payload *prep) 799 { 800 struct encrypted_key_payload *epayload = NULL; 801 char *datablob = NULL; 802 const char *format = NULL; 803 char *master_desc = NULL; 804 char *decrypted_datalen = NULL; 805 char *hex_encoded_iv = NULL; 806 size_t datalen = prep->datalen; 807 int ret; 808 809 if (datalen <= 0 || datalen > 32767 || !prep->data) 810 return -EINVAL; 811 812 datablob = kmalloc(datalen + 1, GFP_KERNEL); 813 if (!datablob) 814 return -ENOMEM; 815 datablob[datalen] = 0; 816 memcpy(datablob, prep->data, datalen); 817 ret = datablob_parse(datablob, &format, &master_desc, 818 &decrypted_datalen, &hex_encoded_iv); 819 if (ret < 0) 820 goto out; 821 822 epayload = encrypted_key_alloc(key, format, master_desc, 823 decrypted_datalen); 824 if (IS_ERR(epayload)) { 825 ret = PTR_ERR(epayload); 826 goto out; 827 } 828 ret = encrypted_init(epayload, key->description, format, master_desc, 829 decrypted_datalen, hex_encoded_iv); 830 if (ret < 0) { 831 kfree(epayload); 832 goto out; 833 } 834 835 rcu_assign_keypointer(key, epayload); 836 out: 837 kfree(datablob); 838 return ret; 839 } 840 841 static void encrypted_rcu_free(struct rcu_head *rcu) 842 { 843 struct encrypted_key_payload *epayload; 844 845 epayload = container_of(rcu, struct encrypted_key_payload, rcu); 846 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); 847 kfree(epayload); 848 } 849 850 /* 851 * encrypted_update - update the master key description 852 * 853 * Change the master key description for an existing encrypted key. 854 * The next read will return an encrypted datablob using the new 855 * master key description. 856 * 857 * On success, return 0. Otherwise return errno. 858 */ 859 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) 860 { 861 struct encrypted_key_payload *epayload = key->payload.data[0]; 862 struct encrypted_key_payload *new_epayload; 863 char *buf; 864 char *new_master_desc = NULL; 865 const char *format = NULL; 866 size_t datalen = prep->datalen; 867 int ret = 0; 868 869 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) 870 return -ENOKEY; 871 if (datalen <= 0 || datalen > 32767 || !prep->data) 872 return -EINVAL; 873 874 buf = kmalloc(datalen + 1, GFP_KERNEL); 875 if (!buf) 876 return -ENOMEM; 877 878 buf[datalen] = 0; 879 memcpy(buf, prep->data, datalen); 880 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); 881 if (ret < 0) 882 goto out; 883 884 ret = valid_master_desc(new_master_desc, epayload->master_desc); 885 if (ret < 0) 886 goto out; 887 888 new_epayload = encrypted_key_alloc(key, epayload->format, 889 new_master_desc, epayload->datalen); 890 if (IS_ERR(new_epayload)) { 891 ret = PTR_ERR(new_epayload); 892 goto out; 893 } 894 895 __ekey_init(new_epayload, epayload->format, new_master_desc, 896 epayload->datalen); 897 898 memcpy(new_epayload->iv, epayload->iv, ivsize); 899 memcpy(new_epayload->payload_data, epayload->payload_data, 900 epayload->payload_datalen); 901 902 rcu_assign_keypointer(key, new_epayload); 903 call_rcu(&epayload->rcu, encrypted_rcu_free); 904 out: 905 kfree(buf); 906 return ret; 907 } 908 909 /* 910 * encrypted_read - format and copy the encrypted data to userspace 911 * 912 * The resulting datablob format is: 913 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> 914 * 915 * On success, return to userspace the encrypted key datablob size. 916 */ 917 static long encrypted_read(const struct key *key, char __user *buffer, 918 size_t buflen) 919 { 920 struct encrypted_key_payload *epayload; 921 struct key *mkey; 922 const u8 *master_key; 923 size_t master_keylen; 924 char derived_key[HASH_SIZE]; 925 char *ascii_buf; 926 size_t asciiblob_len; 927 int ret; 928 929 epayload = dereference_key_locked(key); 930 931 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ 932 asciiblob_len = epayload->datablob_len + ivsize + 1 933 + roundup(epayload->decrypted_datalen, blksize) 934 + (HASH_SIZE * 2); 935 936 if (!buffer || buflen < asciiblob_len) 937 return asciiblob_len; 938 939 mkey = request_master_key(epayload, &master_key, &master_keylen); 940 if (IS_ERR(mkey)) 941 return PTR_ERR(mkey); 942 943 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 944 if (ret < 0) 945 goto out; 946 947 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); 948 if (ret < 0) 949 goto out; 950 951 ret = datablob_hmac_append(epayload, master_key, master_keylen); 952 if (ret < 0) 953 goto out; 954 955 ascii_buf = datablob_format(epayload, asciiblob_len); 956 if (!ascii_buf) { 957 ret = -ENOMEM; 958 goto out; 959 } 960 961 up_read(&mkey->sem); 962 key_put(mkey); 963 964 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) 965 ret = -EFAULT; 966 kfree(ascii_buf); 967 968 return asciiblob_len; 969 out: 970 up_read(&mkey->sem); 971 key_put(mkey); 972 return ret; 973 } 974 975 /* 976 * encrypted_destroy - before freeing the key, clear the decrypted data 977 * 978 * Before freeing the key, clear the memory containing the decrypted 979 * key data. 980 */ 981 static void encrypted_destroy(struct key *key) 982 { 983 struct encrypted_key_payload *epayload = key->payload.data[0]; 984 985 if (!epayload) 986 return; 987 988 memzero_explicit(epayload->decrypted_data, epayload->decrypted_datalen); 989 kfree(key->payload.data[0]); 990 } 991 992 struct key_type key_type_encrypted = { 993 .name = "encrypted", 994 .instantiate = encrypted_instantiate, 995 .update = encrypted_update, 996 .destroy = encrypted_destroy, 997 .describe = user_describe, 998 .read = encrypted_read, 999 }; 1000 EXPORT_SYMBOL_GPL(key_type_encrypted); 1001 1002 static void encrypted_shash_release(void) 1003 { 1004 if (hashalg) 1005 crypto_free_shash(hashalg); 1006 if (hmacalg) 1007 crypto_free_shash(hmacalg); 1008 } 1009 1010 static int __init encrypted_shash_alloc(void) 1011 { 1012 int ret; 1013 1014 hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC); 1015 if (IS_ERR(hmacalg)) { 1016 pr_info("encrypted_key: could not allocate crypto %s\n", 1017 hmac_alg); 1018 return PTR_ERR(hmacalg); 1019 } 1020 1021 hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC); 1022 if (IS_ERR(hashalg)) { 1023 pr_info("encrypted_key: could not allocate crypto %s\n", 1024 hash_alg); 1025 ret = PTR_ERR(hashalg); 1026 goto hashalg_fail; 1027 } 1028 1029 return 0; 1030 1031 hashalg_fail: 1032 crypto_free_shash(hmacalg); 1033 return ret; 1034 } 1035 1036 static int __init init_encrypted(void) 1037 { 1038 int ret; 1039 1040 ret = encrypted_shash_alloc(); 1041 if (ret < 0) 1042 return ret; 1043 ret = aes_get_sizes(); 1044 if (ret < 0) 1045 goto out; 1046 ret = register_key_type(&key_type_encrypted); 1047 if (ret < 0) 1048 goto out; 1049 return 0; 1050 out: 1051 encrypted_shash_release(); 1052 return ret; 1053 1054 } 1055 1056 static void __exit cleanup_encrypted(void) 1057 { 1058 encrypted_shash_release(); 1059 unregister_key_type(&key_type_encrypted); 1060 } 1061 1062 late_initcall(init_encrypted); 1063 module_exit(cleanup_encrypted); 1064 1065 MODULE_LICENSE("GPL"); 1066