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 const char key_format_enc32[] = "enc32"; 49 static unsigned int ivsize; 50 static int blksize; 51 52 #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) 53 #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) 54 #define KEY_ECRYPTFS_DESC_LEN 16 55 #define HASH_SIZE SHA256_DIGEST_SIZE 56 #define MAX_DATA_SIZE 4096 57 #define MIN_DATA_SIZE 20 58 #define KEY_ENC32_PAYLOAD_LEN 32 59 60 static struct crypto_shash *hash_tfm; 61 62 enum { 63 Opt_new, Opt_load, Opt_update, Opt_err 64 }; 65 66 enum { 67 Opt_default, Opt_ecryptfs, Opt_enc32, Opt_error 68 }; 69 70 static const match_table_t key_format_tokens = { 71 {Opt_default, "default"}, 72 {Opt_ecryptfs, "ecryptfs"}, 73 {Opt_enc32, "enc32"}, 74 {Opt_error, NULL} 75 }; 76 77 static const match_table_t key_tokens = { 78 {Opt_new, "new"}, 79 {Opt_load, "load"}, 80 {Opt_update, "update"}, 81 {Opt_err, NULL} 82 }; 83 84 static int aes_get_sizes(void) 85 { 86 struct crypto_skcipher *tfm; 87 88 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 89 if (IS_ERR(tfm)) { 90 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n", 91 PTR_ERR(tfm)); 92 return PTR_ERR(tfm); 93 } 94 ivsize = crypto_skcipher_ivsize(tfm); 95 blksize = crypto_skcipher_blocksize(tfm); 96 crypto_free_skcipher(tfm); 97 return 0; 98 } 99 100 /* 101 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key 102 * 103 * The description of a encrypted key with format 'ecryptfs' must contain 104 * exactly 16 hexadecimal characters. 105 * 106 */ 107 static int valid_ecryptfs_desc(const char *ecryptfs_desc) 108 { 109 int i; 110 111 if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) { 112 pr_err("encrypted_key: key description must be %d hexadecimal " 113 "characters long\n", KEY_ECRYPTFS_DESC_LEN); 114 return -EINVAL; 115 } 116 117 for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) { 118 if (!isxdigit(ecryptfs_desc[i])) { 119 pr_err("encrypted_key: key description must contain " 120 "only hexadecimal characters\n"); 121 return -EINVAL; 122 } 123 } 124 125 return 0; 126 } 127 128 /* 129 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key 130 * 131 * key-type:= "trusted:" | "user:" 132 * desc:= master-key description 133 * 134 * Verify that 'key-type' is valid and that 'desc' exists. On key update, 135 * only the master key description is permitted to change, not the key-type. 136 * The key-type remains constant. 137 * 138 * On success returns 0, otherwise -EINVAL. 139 */ 140 static int valid_master_desc(const char *new_desc, const char *orig_desc) 141 { 142 int prefix_len; 143 144 if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) 145 prefix_len = KEY_TRUSTED_PREFIX_LEN; 146 else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) 147 prefix_len = KEY_USER_PREFIX_LEN; 148 else 149 return -EINVAL; 150 151 if (!new_desc[prefix_len]) 152 return -EINVAL; 153 154 if (orig_desc && strncmp(new_desc, orig_desc, prefix_len)) 155 return -EINVAL; 156 157 return 0; 158 } 159 160 /* 161 * datablob_parse - parse the keyctl data 162 * 163 * datablob format: 164 * new [<format>] <master-key name> <decrypted data length> 165 * load [<format>] <master-key name> <decrypted data length> 166 * <encrypted iv + data> 167 * update <new-master-key name> 168 * 169 * Tokenizes a copy of the keyctl data, returning a pointer to each token, 170 * which is null terminated. 171 * 172 * On success returns 0, otherwise -EINVAL. 173 */ 174 static int datablob_parse(char *datablob, const char **format, 175 char **master_desc, char **decrypted_datalen, 176 char **hex_encoded_iv) 177 { 178 substring_t args[MAX_OPT_ARGS]; 179 int ret = -EINVAL; 180 int key_cmd; 181 int key_format; 182 char *p, *keyword; 183 184 keyword = strsep(&datablob, " \t"); 185 if (!keyword) { 186 pr_info("encrypted_key: insufficient parameters specified\n"); 187 return ret; 188 } 189 key_cmd = match_token(keyword, key_tokens, args); 190 191 /* Get optional format: default | ecryptfs */ 192 p = strsep(&datablob, " \t"); 193 if (!p) { 194 pr_err("encrypted_key: insufficient parameters specified\n"); 195 return ret; 196 } 197 198 key_format = match_token(p, key_format_tokens, args); 199 switch (key_format) { 200 case Opt_ecryptfs: 201 case Opt_enc32: 202 case Opt_default: 203 *format = p; 204 *master_desc = strsep(&datablob, " \t"); 205 break; 206 case Opt_error: 207 *master_desc = p; 208 break; 209 } 210 211 if (!*master_desc) { 212 pr_info("encrypted_key: master key parameter is missing\n"); 213 goto out; 214 } 215 216 if (valid_master_desc(*master_desc, NULL) < 0) { 217 pr_info("encrypted_key: master key parameter \'%s\' " 218 "is invalid\n", *master_desc); 219 goto out; 220 } 221 222 if (decrypted_datalen) { 223 *decrypted_datalen = strsep(&datablob, " \t"); 224 if (!*decrypted_datalen) { 225 pr_info("encrypted_key: keylen parameter is missing\n"); 226 goto out; 227 } 228 } 229 230 switch (key_cmd) { 231 case Opt_new: 232 if (!decrypted_datalen) { 233 pr_info("encrypted_key: keyword \'%s\' not allowed " 234 "when called from .update method\n", keyword); 235 break; 236 } 237 ret = 0; 238 break; 239 case Opt_load: 240 if (!decrypted_datalen) { 241 pr_info("encrypted_key: keyword \'%s\' not allowed " 242 "when called from .update method\n", keyword); 243 break; 244 } 245 *hex_encoded_iv = strsep(&datablob, " \t"); 246 if (!*hex_encoded_iv) { 247 pr_info("encrypted_key: hex blob is missing\n"); 248 break; 249 } 250 ret = 0; 251 break; 252 case Opt_update: 253 if (decrypted_datalen) { 254 pr_info("encrypted_key: keyword \'%s\' not allowed " 255 "when called from .instantiate method\n", 256 keyword); 257 break; 258 } 259 ret = 0; 260 break; 261 case Opt_err: 262 pr_info("encrypted_key: keyword \'%s\' not recognized\n", 263 keyword); 264 break; 265 } 266 out: 267 return ret; 268 } 269 270 /* 271 * datablob_format - format as an ascii string, before copying to userspace 272 */ 273 static char *datablob_format(struct encrypted_key_payload *epayload, 274 size_t asciiblob_len) 275 { 276 char *ascii_buf, *bufp; 277 u8 *iv = epayload->iv; 278 int len; 279 int i; 280 281 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); 282 if (!ascii_buf) 283 goto out; 284 285 ascii_buf[asciiblob_len] = '\0'; 286 287 /* copy datablob master_desc and datalen strings */ 288 len = sprintf(ascii_buf, "%s %s %s ", epayload->format, 289 epayload->master_desc, epayload->datalen); 290 291 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ 292 bufp = &ascii_buf[len]; 293 for (i = 0; i < (asciiblob_len - len) / 2; i++) 294 bufp = hex_byte_pack(bufp, iv[i]); 295 out: 296 return ascii_buf; 297 } 298 299 /* 300 * request_user_key - request the user key 301 * 302 * Use a user provided key to encrypt/decrypt an encrypted-key. 303 */ 304 static struct key *request_user_key(const char *master_desc, const u8 **master_key, 305 size_t *master_keylen) 306 { 307 const struct user_key_payload *upayload; 308 struct key *ukey; 309 310 ukey = request_key(&key_type_user, master_desc, NULL); 311 if (IS_ERR(ukey)) 312 goto error; 313 314 down_read(&ukey->sem); 315 upayload = user_key_payload_locked(ukey); 316 if (!upayload) { 317 /* key was revoked before we acquired its semaphore */ 318 up_read(&ukey->sem); 319 key_put(ukey); 320 ukey = ERR_PTR(-EKEYREVOKED); 321 goto error; 322 } 323 *master_key = upayload->data; 324 *master_keylen = upayload->datalen; 325 error: 326 return ukey; 327 } 328 329 static int calc_hash(struct crypto_shash *tfm, u8 *digest, 330 const u8 *buf, unsigned int buflen) 331 { 332 SHASH_DESC_ON_STACK(desc, tfm); 333 int err; 334 335 desc->tfm = tfm; 336 desc->flags = 0; 337 338 err = crypto_shash_digest(desc, buf, buflen, digest); 339 shash_desc_zero(desc); 340 return err; 341 } 342 343 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, 344 const u8 *buf, unsigned int buflen) 345 { 346 struct crypto_shash *tfm; 347 int err; 348 349 tfm = crypto_alloc_shash(hmac_alg, 0, 0); 350 if (IS_ERR(tfm)) { 351 pr_err("encrypted_key: can't alloc %s transform: %ld\n", 352 hmac_alg, PTR_ERR(tfm)); 353 return PTR_ERR(tfm); 354 } 355 356 err = crypto_shash_setkey(tfm, key, keylen); 357 if (!err) 358 err = calc_hash(tfm, digest, buf, buflen); 359 crypto_free_shash(tfm); 360 return err; 361 } 362 363 enum derived_key_type { ENC_KEY, AUTH_KEY }; 364 365 /* Derive authentication/encryption key from trusted key */ 366 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, 367 const u8 *master_key, size_t master_keylen) 368 { 369 u8 *derived_buf; 370 unsigned int derived_buf_len; 371 int ret; 372 373 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; 374 if (derived_buf_len < HASH_SIZE) 375 derived_buf_len = HASH_SIZE; 376 377 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); 378 if (!derived_buf) 379 return -ENOMEM; 380 381 if (key_type) 382 strcpy(derived_buf, "AUTH_KEY"); 383 else 384 strcpy(derived_buf, "ENC_KEY"); 385 386 memcpy(derived_buf + strlen(derived_buf) + 1, master_key, 387 master_keylen); 388 ret = calc_hash(hash_tfm, derived_key, derived_buf, derived_buf_len); 389 kzfree(derived_buf); 390 return ret; 391 } 392 393 static struct skcipher_request *init_skcipher_req(const u8 *key, 394 unsigned int key_len) 395 { 396 struct skcipher_request *req; 397 struct crypto_skcipher *tfm; 398 int ret; 399 400 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 401 if (IS_ERR(tfm)) { 402 pr_err("encrypted_key: failed to load %s transform (%ld)\n", 403 blkcipher_alg, PTR_ERR(tfm)); 404 return ERR_CAST(tfm); 405 } 406 407 ret = crypto_skcipher_setkey(tfm, key, key_len); 408 if (ret < 0) { 409 pr_err("encrypted_key: failed to setkey (%d)\n", ret); 410 crypto_free_skcipher(tfm); 411 return ERR_PTR(ret); 412 } 413 414 req = skcipher_request_alloc(tfm, GFP_KERNEL); 415 if (!req) { 416 pr_err("encrypted_key: failed to allocate request for %s\n", 417 blkcipher_alg); 418 crypto_free_skcipher(tfm); 419 return ERR_PTR(-ENOMEM); 420 } 421 422 skcipher_request_set_callback(req, 0, NULL, NULL); 423 return req; 424 } 425 426 static struct key *request_master_key(struct encrypted_key_payload *epayload, 427 const u8 **master_key, size_t *master_keylen) 428 { 429 struct key *mkey = ERR_PTR(-EINVAL); 430 431 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, 432 KEY_TRUSTED_PREFIX_LEN)) { 433 mkey = request_trusted_key(epayload->master_desc + 434 KEY_TRUSTED_PREFIX_LEN, 435 master_key, master_keylen); 436 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, 437 KEY_USER_PREFIX_LEN)) { 438 mkey = request_user_key(epayload->master_desc + 439 KEY_USER_PREFIX_LEN, 440 master_key, master_keylen); 441 } else 442 goto out; 443 444 if (IS_ERR(mkey)) { 445 int ret = PTR_ERR(mkey); 446 447 if (ret == -ENOTSUPP) 448 pr_info("encrypted_key: key %s not supported", 449 epayload->master_desc); 450 else 451 pr_info("encrypted_key: key %s not found", 452 epayload->master_desc); 453 goto out; 454 } 455 456 dump_master_key(*master_key, *master_keylen); 457 out: 458 return mkey; 459 } 460 461 /* Before returning data to userspace, encrypt decrypted data. */ 462 static int derived_key_encrypt(struct encrypted_key_payload *epayload, 463 const u8 *derived_key, 464 unsigned int derived_keylen) 465 { 466 struct scatterlist sg_in[2]; 467 struct scatterlist sg_out[1]; 468 struct crypto_skcipher *tfm; 469 struct skcipher_request *req; 470 unsigned int encrypted_datalen; 471 u8 iv[AES_BLOCK_SIZE]; 472 int ret; 473 474 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 475 476 req = init_skcipher_req(derived_key, derived_keylen); 477 ret = PTR_ERR(req); 478 if (IS_ERR(req)) 479 goto out; 480 dump_decrypted_data(epayload); 481 482 sg_init_table(sg_in, 2); 483 sg_set_buf(&sg_in[0], epayload->decrypted_data, 484 epayload->decrypted_datalen); 485 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0); 486 487 sg_init_table(sg_out, 1); 488 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); 489 490 memcpy(iv, epayload->iv, sizeof(iv)); 491 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 492 ret = crypto_skcipher_encrypt(req); 493 tfm = crypto_skcipher_reqtfm(req); 494 skcipher_request_free(req); 495 crypto_free_skcipher(tfm); 496 if (ret < 0) 497 pr_err("encrypted_key: failed to encrypt (%d)\n", ret); 498 else 499 dump_encrypted_data(epayload, encrypted_datalen); 500 out: 501 return ret; 502 } 503 504 static int datablob_hmac_append(struct encrypted_key_payload *epayload, 505 const u8 *master_key, size_t master_keylen) 506 { 507 u8 derived_key[HASH_SIZE]; 508 u8 *digest; 509 int ret; 510 511 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 512 if (ret < 0) 513 goto out; 514 515 digest = epayload->format + epayload->datablob_len; 516 ret = calc_hmac(digest, derived_key, sizeof derived_key, 517 epayload->format, epayload->datablob_len); 518 if (!ret) 519 dump_hmac(NULL, digest, HASH_SIZE); 520 out: 521 memzero_explicit(derived_key, sizeof(derived_key)); 522 return ret; 523 } 524 525 /* verify HMAC before decrypting encrypted key */ 526 static int datablob_hmac_verify(struct encrypted_key_payload *epayload, 527 const u8 *format, const u8 *master_key, 528 size_t master_keylen) 529 { 530 u8 derived_key[HASH_SIZE]; 531 u8 digest[HASH_SIZE]; 532 int ret; 533 char *p; 534 unsigned short len; 535 536 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 537 if (ret < 0) 538 goto out; 539 540 len = epayload->datablob_len; 541 if (!format) { 542 p = epayload->master_desc; 543 len -= strlen(epayload->format) + 1; 544 } else 545 p = epayload->format; 546 547 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); 548 if (ret < 0) 549 goto out; 550 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len, 551 sizeof(digest)); 552 if (ret) { 553 ret = -EINVAL; 554 dump_hmac("datablob", 555 epayload->format + epayload->datablob_len, 556 HASH_SIZE); 557 dump_hmac("calc", digest, HASH_SIZE); 558 } 559 out: 560 memzero_explicit(derived_key, sizeof(derived_key)); 561 return ret; 562 } 563 564 static int derived_key_decrypt(struct encrypted_key_payload *epayload, 565 const u8 *derived_key, 566 unsigned int derived_keylen) 567 { 568 struct scatterlist sg_in[1]; 569 struct scatterlist sg_out[2]; 570 struct crypto_skcipher *tfm; 571 struct skcipher_request *req; 572 unsigned int encrypted_datalen; 573 u8 iv[AES_BLOCK_SIZE]; 574 u8 *pad; 575 int ret; 576 577 /* Throwaway buffer to hold the unused zero padding at the end */ 578 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL); 579 if (!pad) 580 return -ENOMEM; 581 582 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 583 req = init_skcipher_req(derived_key, derived_keylen); 584 ret = PTR_ERR(req); 585 if (IS_ERR(req)) 586 goto out; 587 dump_encrypted_data(epayload, encrypted_datalen); 588 589 sg_init_table(sg_in, 1); 590 sg_init_table(sg_out, 2); 591 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); 592 sg_set_buf(&sg_out[0], epayload->decrypted_data, 593 epayload->decrypted_datalen); 594 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE); 595 596 memcpy(iv, epayload->iv, sizeof(iv)); 597 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 598 ret = crypto_skcipher_decrypt(req); 599 tfm = crypto_skcipher_reqtfm(req); 600 skcipher_request_free(req); 601 crypto_free_skcipher(tfm); 602 if (ret < 0) 603 goto out; 604 dump_decrypted_data(epayload); 605 out: 606 kfree(pad); 607 return ret; 608 } 609 610 /* Allocate memory for decrypted key and datablob. */ 611 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, 612 const char *format, 613 const char *master_desc, 614 const char *datalen) 615 { 616 struct encrypted_key_payload *epayload = NULL; 617 unsigned short datablob_len; 618 unsigned short decrypted_datalen; 619 unsigned short payload_datalen; 620 unsigned int encrypted_datalen; 621 unsigned int format_len; 622 long dlen; 623 int ret; 624 625 ret = kstrtol(datalen, 10, &dlen); 626 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) 627 return ERR_PTR(-EINVAL); 628 629 format_len = (!format) ? strlen(key_format_default) : strlen(format); 630 decrypted_datalen = dlen; 631 payload_datalen = decrypted_datalen; 632 if (format) { 633 if (!strcmp(format, key_format_ecryptfs)) { 634 if (dlen != ECRYPTFS_MAX_KEY_BYTES) { 635 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n", 636 ECRYPTFS_MAX_KEY_BYTES); 637 return ERR_PTR(-EINVAL); 638 } 639 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; 640 payload_datalen = sizeof(struct ecryptfs_auth_tok); 641 } else if (!strcmp(format, key_format_enc32)) { 642 if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) { 643 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n", 644 decrypted_datalen); 645 return ERR_PTR(-EINVAL); 646 } 647 } 648 } 649 650 encrypted_datalen = roundup(decrypted_datalen, blksize); 651 652 datablob_len = format_len + 1 + strlen(master_desc) + 1 653 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; 654 655 ret = key_payload_reserve(key, payload_datalen + datablob_len 656 + HASH_SIZE + 1); 657 if (ret < 0) 658 return ERR_PTR(ret); 659 660 epayload = kzalloc(sizeof(*epayload) + payload_datalen + 661 datablob_len + HASH_SIZE + 1, GFP_KERNEL); 662 if (!epayload) 663 return ERR_PTR(-ENOMEM); 664 665 epayload->payload_datalen = payload_datalen; 666 epayload->decrypted_datalen = decrypted_datalen; 667 epayload->datablob_len = datablob_len; 668 return epayload; 669 } 670 671 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, 672 const char *format, const char *hex_encoded_iv) 673 { 674 struct key *mkey; 675 u8 derived_key[HASH_SIZE]; 676 const u8 *master_key; 677 u8 *hmac; 678 const char *hex_encoded_data; 679 unsigned int encrypted_datalen; 680 size_t master_keylen; 681 size_t asciilen; 682 int ret; 683 684 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 685 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; 686 if (strlen(hex_encoded_iv) != asciilen) 687 return -EINVAL; 688 689 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; 690 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); 691 if (ret < 0) 692 return -EINVAL; 693 ret = hex2bin(epayload->encrypted_data, hex_encoded_data, 694 encrypted_datalen); 695 if (ret < 0) 696 return -EINVAL; 697 698 hmac = epayload->format + epayload->datablob_len; 699 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), 700 HASH_SIZE); 701 if (ret < 0) 702 return -EINVAL; 703 704 mkey = request_master_key(epayload, &master_key, &master_keylen); 705 if (IS_ERR(mkey)) 706 return PTR_ERR(mkey); 707 708 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); 709 if (ret < 0) { 710 pr_err("encrypted_key: bad hmac (%d)\n", ret); 711 goto out; 712 } 713 714 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 715 if (ret < 0) 716 goto out; 717 718 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); 719 if (ret < 0) 720 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); 721 out: 722 up_read(&mkey->sem); 723 key_put(mkey); 724 memzero_explicit(derived_key, sizeof(derived_key)); 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 kzfree(epayload); 832 goto out; 833 } 834 835 rcu_assign_keypointer(key, epayload); 836 out: 837 kzfree(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 kzfree(epayload); 847 } 848 849 /* 850 * encrypted_update - update the master key description 851 * 852 * Change the master key description for an existing encrypted key. 853 * The next read will return an encrypted datablob using the new 854 * master key description. 855 * 856 * On success, return 0. Otherwise return errno. 857 */ 858 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) 859 { 860 struct encrypted_key_payload *epayload = key->payload.data[0]; 861 struct encrypted_key_payload *new_epayload; 862 char *buf; 863 char *new_master_desc = NULL; 864 const char *format = NULL; 865 size_t datalen = prep->datalen; 866 int ret = 0; 867 868 if (key_is_negative(key)) 869 return -ENOKEY; 870 if (datalen <= 0 || datalen > 32767 || !prep->data) 871 return -EINVAL; 872 873 buf = kmalloc(datalen + 1, GFP_KERNEL); 874 if (!buf) 875 return -ENOMEM; 876 877 buf[datalen] = 0; 878 memcpy(buf, prep->data, datalen); 879 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); 880 if (ret < 0) 881 goto out; 882 883 ret = valid_master_desc(new_master_desc, epayload->master_desc); 884 if (ret < 0) 885 goto out; 886 887 new_epayload = encrypted_key_alloc(key, epayload->format, 888 new_master_desc, epayload->datalen); 889 if (IS_ERR(new_epayload)) { 890 ret = PTR_ERR(new_epayload); 891 goto out; 892 } 893 894 __ekey_init(new_epayload, epayload->format, new_master_desc, 895 epayload->datalen); 896 897 memcpy(new_epayload->iv, epayload->iv, ivsize); 898 memcpy(new_epayload->payload_data, epayload->payload_data, 899 epayload->payload_datalen); 900 901 rcu_assign_keypointer(key, new_epayload); 902 call_rcu(&epayload->rcu, encrypted_rcu_free); 903 out: 904 kzfree(buf); 905 return ret; 906 } 907 908 /* 909 * encrypted_read - format and copy the encrypted data to userspace 910 * 911 * The resulting datablob format is: 912 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> 913 * 914 * On success, return to userspace the encrypted key datablob size. 915 */ 916 static long encrypted_read(const struct key *key, char __user *buffer, 917 size_t buflen) 918 { 919 struct encrypted_key_payload *epayload; 920 struct key *mkey; 921 const u8 *master_key; 922 size_t master_keylen; 923 char derived_key[HASH_SIZE]; 924 char *ascii_buf; 925 size_t asciiblob_len; 926 int ret; 927 928 epayload = dereference_key_locked(key); 929 930 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ 931 asciiblob_len = epayload->datablob_len + ivsize + 1 932 + roundup(epayload->decrypted_datalen, blksize) 933 + (HASH_SIZE * 2); 934 935 if (!buffer || buflen < asciiblob_len) 936 return asciiblob_len; 937 938 mkey = request_master_key(epayload, &master_key, &master_keylen); 939 if (IS_ERR(mkey)) 940 return PTR_ERR(mkey); 941 942 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 943 if (ret < 0) 944 goto out; 945 946 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); 947 if (ret < 0) 948 goto out; 949 950 ret = datablob_hmac_append(epayload, master_key, master_keylen); 951 if (ret < 0) 952 goto out; 953 954 ascii_buf = datablob_format(epayload, asciiblob_len); 955 if (!ascii_buf) { 956 ret = -ENOMEM; 957 goto out; 958 } 959 960 up_read(&mkey->sem); 961 key_put(mkey); 962 memzero_explicit(derived_key, sizeof(derived_key)); 963 964 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) 965 ret = -EFAULT; 966 kzfree(ascii_buf); 967 968 return asciiblob_len; 969 out: 970 up_read(&mkey->sem); 971 key_put(mkey); 972 memzero_explicit(derived_key, sizeof(derived_key)); 973 return ret; 974 } 975 976 /* 977 * encrypted_destroy - clear and free the key's payload 978 */ 979 static void encrypted_destroy(struct key *key) 980 { 981 kzfree(key->payload.data[0]); 982 } 983 984 struct key_type key_type_encrypted = { 985 .name = "encrypted", 986 .instantiate = encrypted_instantiate, 987 .update = encrypted_update, 988 .destroy = encrypted_destroy, 989 .describe = user_describe, 990 .read = encrypted_read, 991 }; 992 EXPORT_SYMBOL_GPL(key_type_encrypted); 993 994 static int __init init_encrypted(void) 995 { 996 int ret; 997 998 hash_tfm = crypto_alloc_shash(hash_alg, 0, 0); 999 if (IS_ERR(hash_tfm)) { 1000 pr_err("encrypted_key: can't allocate %s transform: %ld\n", 1001 hash_alg, PTR_ERR(hash_tfm)); 1002 return PTR_ERR(hash_tfm); 1003 } 1004 1005 ret = aes_get_sizes(); 1006 if (ret < 0) 1007 goto out; 1008 ret = register_key_type(&key_type_encrypted); 1009 if (ret < 0) 1010 goto out; 1011 return 0; 1012 out: 1013 crypto_free_shash(hash_tfm); 1014 return ret; 1015 1016 } 1017 1018 static void __exit cleanup_encrypted(void) 1019 { 1020 crypto_free_shash(hash_tfm); 1021 unregister_key_type(&key_type_encrypted); 1022 } 1023 1024 late_initcall(init_encrypted); 1025 module_exit(cleanup_encrypted); 1026 1027 MODULE_LICENSE("GPL"); 1028