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