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; 336 337 err = crypto_shash_digest(desc, buf, buflen, digest); 338 shash_desc_zero(desc); 339 return err; 340 } 341 342 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, 343 const u8 *buf, unsigned int buflen) 344 { 345 struct crypto_shash *tfm; 346 int err; 347 348 tfm = crypto_alloc_shash(hmac_alg, 0, 0); 349 if (IS_ERR(tfm)) { 350 pr_err("encrypted_key: can't alloc %s transform: %ld\n", 351 hmac_alg, PTR_ERR(tfm)); 352 return PTR_ERR(tfm); 353 } 354 355 err = crypto_shash_setkey(tfm, key, keylen); 356 if (!err) 357 err = calc_hash(tfm, digest, buf, buflen); 358 crypto_free_shash(tfm); 359 return err; 360 } 361 362 enum derived_key_type { ENC_KEY, AUTH_KEY }; 363 364 /* Derive authentication/encryption key from trusted key */ 365 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, 366 const u8 *master_key, size_t master_keylen) 367 { 368 u8 *derived_buf; 369 unsigned int derived_buf_len; 370 int ret; 371 372 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; 373 if (derived_buf_len < HASH_SIZE) 374 derived_buf_len = HASH_SIZE; 375 376 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); 377 if (!derived_buf) 378 return -ENOMEM; 379 380 if (key_type) 381 strcpy(derived_buf, "AUTH_KEY"); 382 else 383 strcpy(derived_buf, "ENC_KEY"); 384 385 memcpy(derived_buf + strlen(derived_buf) + 1, master_key, 386 master_keylen); 387 ret = calc_hash(hash_tfm, derived_key, derived_buf, derived_buf_len); 388 kzfree(derived_buf); 389 return ret; 390 } 391 392 static struct skcipher_request *init_skcipher_req(const u8 *key, 393 unsigned int key_len) 394 { 395 struct skcipher_request *req; 396 struct crypto_skcipher *tfm; 397 int ret; 398 399 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 400 if (IS_ERR(tfm)) { 401 pr_err("encrypted_key: failed to load %s transform (%ld)\n", 402 blkcipher_alg, PTR_ERR(tfm)); 403 return ERR_CAST(tfm); 404 } 405 406 ret = crypto_skcipher_setkey(tfm, key, key_len); 407 if (ret < 0) { 408 pr_err("encrypted_key: failed to setkey (%d)\n", ret); 409 crypto_free_skcipher(tfm); 410 return ERR_PTR(ret); 411 } 412 413 req = skcipher_request_alloc(tfm, GFP_KERNEL); 414 if (!req) { 415 pr_err("encrypted_key: failed to allocate request for %s\n", 416 blkcipher_alg); 417 crypto_free_skcipher(tfm); 418 return ERR_PTR(-ENOMEM); 419 } 420 421 skcipher_request_set_callback(req, 0, NULL, NULL); 422 return req; 423 } 424 425 static struct key *request_master_key(struct encrypted_key_payload *epayload, 426 const u8 **master_key, size_t *master_keylen) 427 { 428 struct key *mkey = ERR_PTR(-EINVAL); 429 430 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, 431 KEY_TRUSTED_PREFIX_LEN)) { 432 mkey = request_trusted_key(epayload->master_desc + 433 KEY_TRUSTED_PREFIX_LEN, 434 master_key, master_keylen); 435 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, 436 KEY_USER_PREFIX_LEN)) { 437 mkey = request_user_key(epayload->master_desc + 438 KEY_USER_PREFIX_LEN, 439 master_key, master_keylen); 440 } else 441 goto out; 442 443 if (IS_ERR(mkey)) { 444 int ret = PTR_ERR(mkey); 445 446 if (ret == -ENOTSUPP) 447 pr_info("encrypted_key: key %s not supported", 448 epayload->master_desc); 449 else 450 pr_info("encrypted_key: key %s not found", 451 epayload->master_desc); 452 goto out; 453 } 454 455 dump_master_key(*master_key, *master_keylen); 456 out: 457 return mkey; 458 } 459 460 /* Before returning data to userspace, encrypt decrypted data. */ 461 static int derived_key_encrypt(struct encrypted_key_payload *epayload, 462 const u8 *derived_key, 463 unsigned int derived_keylen) 464 { 465 struct scatterlist sg_in[2]; 466 struct scatterlist sg_out[1]; 467 struct crypto_skcipher *tfm; 468 struct skcipher_request *req; 469 unsigned int encrypted_datalen; 470 u8 iv[AES_BLOCK_SIZE]; 471 int ret; 472 473 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 474 475 req = init_skcipher_req(derived_key, derived_keylen); 476 ret = PTR_ERR(req); 477 if (IS_ERR(req)) 478 goto out; 479 dump_decrypted_data(epayload); 480 481 sg_init_table(sg_in, 2); 482 sg_set_buf(&sg_in[0], epayload->decrypted_data, 483 epayload->decrypted_datalen); 484 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0); 485 486 sg_init_table(sg_out, 1); 487 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); 488 489 memcpy(iv, epayload->iv, sizeof(iv)); 490 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 491 ret = crypto_skcipher_encrypt(req); 492 tfm = crypto_skcipher_reqtfm(req); 493 skcipher_request_free(req); 494 crypto_free_skcipher(tfm); 495 if (ret < 0) 496 pr_err("encrypted_key: failed to encrypt (%d)\n", ret); 497 else 498 dump_encrypted_data(epayload, encrypted_datalen); 499 out: 500 return ret; 501 } 502 503 static int datablob_hmac_append(struct encrypted_key_payload *epayload, 504 const u8 *master_key, size_t master_keylen) 505 { 506 u8 derived_key[HASH_SIZE]; 507 u8 *digest; 508 int ret; 509 510 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 511 if (ret < 0) 512 goto out; 513 514 digest = epayload->format + epayload->datablob_len; 515 ret = calc_hmac(digest, derived_key, sizeof derived_key, 516 epayload->format, epayload->datablob_len); 517 if (!ret) 518 dump_hmac(NULL, digest, HASH_SIZE); 519 out: 520 memzero_explicit(derived_key, sizeof(derived_key)); 521 return ret; 522 } 523 524 /* verify HMAC before decrypting encrypted key */ 525 static int datablob_hmac_verify(struct encrypted_key_payload *epayload, 526 const u8 *format, const u8 *master_key, 527 size_t master_keylen) 528 { 529 u8 derived_key[HASH_SIZE]; 530 u8 digest[HASH_SIZE]; 531 int ret; 532 char *p; 533 unsigned short len; 534 535 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 536 if (ret < 0) 537 goto out; 538 539 len = epayload->datablob_len; 540 if (!format) { 541 p = epayload->master_desc; 542 len -= strlen(epayload->format) + 1; 543 } else 544 p = epayload->format; 545 546 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); 547 if (ret < 0) 548 goto out; 549 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len, 550 sizeof(digest)); 551 if (ret) { 552 ret = -EINVAL; 553 dump_hmac("datablob", 554 epayload->format + epayload->datablob_len, 555 HASH_SIZE); 556 dump_hmac("calc", digest, HASH_SIZE); 557 } 558 out: 559 memzero_explicit(derived_key, sizeof(derived_key)); 560 return ret; 561 } 562 563 static int derived_key_decrypt(struct encrypted_key_payload *epayload, 564 const u8 *derived_key, 565 unsigned int derived_keylen) 566 { 567 struct scatterlist sg_in[1]; 568 struct scatterlist sg_out[2]; 569 struct crypto_skcipher *tfm; 570 struct skcipher_request *req; 571 unsigned int encrypted_datalen; 572 u8 iv[AES_BLOCK_SIZE]; 573 u8 *pad; 574 int ret; 575 576 /* Throwaway buffer to hold the unused zero padding at the end */ 577 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL); 578 if (!pad) 579 return -ENOMEM; 580 581 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 582 req = init_skcipher_req(derived_key, derived_keylen); 583 ret = PTR_ERR(req); 584 if (IS_ERR(req)) 585 goto out; 586 dump_encrypted_data(epayload, encrypted_datalen); 587 588 sg_init_table(sg_in, 1); 589 sg_init_table(sg_out, 2); 590 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); 591 sg_set_buf(&sg_out[0], epayload->decrypted_data, 592 epayload->decrypted_datalen); 593 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE); 594 595 memcpy(iv, epayload->iv, sizeof(iv)); 596 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 597 ret = crypto_skcipher_decrypt(req); 598 tfm = crypto_skcipher_reqtfm(req); 599 skcipher_request_free(req); 600 crypto_free_skcipher(tfm); 601 if (ret < 0) 602 goto out; 603 dump_decrypted_data(epayload); 604 out: 605 kfree(pad); 606 return ret; 607 } 608 609 /* Allocate memory for decrypted key and datablob. */ 610 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, 611 const char *format, 612 const char *master_desc, 613 const char *datalen) 614 { 615 struct encrypted_key_payload *epayload = NULL; 616 unsigned short datablob_len; 617 unsigned short decrypted_datalen; 618 unsigned short payload_datalen; 619 unsigned int encrypted_datalen; 620 unsigned int format_len; 621 long dlen; 622 int ret; 623 624 ret = kstrtol(datalen, 10, &dlen); 625 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) 626 return ERR_PTR(-EINVAL); 627 628 format_len = (!format) ? strlen(key_format_default) : strlen(format); 629 decrypted_datalen = dlen; 630 payload_datalen = decrypted_datalen; 631 if (format) { 632 if (!strcmp(format, key_format_ecryptfs)) { 633 if (dlen != ECRYPTFS_MAX_KEY_BYTES) { 634 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n", 635 ECRYPTFS_MAX_KEY_BYTES); 636 return ERR_PTR(-EINVAL); 637 } 638 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; 639 payload_datalen = sizeof(struct ecryptfs_auth_tok); 640 } else if (!strcmp(format, key_format_enc32)) { 641 if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) { 642 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n", 643 decrypted_datalen); 644 return ERR_PTR(-EINVAL); 645 } 646 } 647 } 648 649 encrypted_datalen = roundup(decrypted_datalen, blksize); 650 651 datablob_len = format_len + 1 + strlen(master_desc) + 1 652 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; 653 654 ret = key_payload_reserve(key, payload_datalen + datablob_len 655 + HASH_SIZE + 1); 656 if (ret < 0) 657 return ERR_PTR(ret); 658 659 epayload = kzalloc(sizeof(*epayload) + payload_datalen + 660 datablob_len + HASH_SIZE + 1, GFP_KERNEL); 661 if (!epayload) 662 return ERR_PTR(-ENOMEM); 663 664 epayload->payload_datalen = payload_datalen; 665 epayload->decrypted_datalen = decrypted_datalen; 666 epayload->datablob_len = datablob_len; 667 return epayload; 668 } 669 670 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, 671 const char *format, const char *hex_encoded_iv) 672 { 673 struct key *mkey; 674 u8 derived_key[HASH_SIZE]; 675 const u8 *master_key; 676 u8 *hmac; 677 const char *hex_encoded_data; 678 unsigned int encrypted_datalen; 679 size_t master_keylen; 680 size_t asciilen; 681 int ret; 682 683 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 684 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; 685 if (strlen(hex_encoded_iv) != asciilen) 686 return -EINVAL; 687 688 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; 689 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); 690 if (ret < 0) 691 return -EINVAL; 692 ret = hex2bin(epayload->encrypted_data, hex_encoded_data, 693 encrypted_datalen); 694 if (ret < 0) 695 return -EINVAL; 696 697 hmac = epayload->format + epayload->datablob_len; 698 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), 699 HASH_SIZE); 700 if (ret < 0) 701 return -EINVAL; 702 703 mkey = request_master_key(epayload, &master_key, &master_keylen); 704 if (IS_ERR(mkey)) 705 return PTR_ERR(mkey); 706 707 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); 708 if (ret < 0) { 709 pr_err("encrypted_key: bad hmac (%d)\n", ret); 710 goto out; 711 } 712 713 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 714 if (ret < 0) 715 goto out; 716 717 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); 718 if (ret < 0) 719 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); 720 out: 721 up_read(&mkey->sem); 722 key_put(mkey); 723 memzero_explicit(derived_key, sizeof(derived_key)); 724 return ret; 725 } 726 727 static void __ekey_init(struct encrypted_key_payload *epayload, 728 const char *format, const char *master_desc, 729 const char *datalen) 730 { 731 unsigned int format_len; 732 733 format_len = (!format) ? strlen(key_format_default) : strlen(format); 734 epayload->format = epayload->payload_data + epayload->payload_datalen; 735 epayload->master_desc = epayload->format + format_len + 1; 736 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; 737 epayload->iv = epayload->datalen + strlen(datalen) + 1; 738 epayload->encrypted_data = epayload->iv + ivsize + 1; 739 epayload->decrypted_data = epayload->payload_data; 740 741 if (!format) 742 memcpy(epayload->format, key_format_default, format_len); 743 else { 744 if (!strcmp(format, key_format_ecryptfs)) 745 epayload->decrypted_data = 746 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); 747 748 memcpy(epayload->format, format, format_len); 749 } 750 751 memcpy(epayload->master_desc, master_desc, strlen(master_desc)); 752 memcpy(epayload->datalen, datalen, strlen(datalen)); 753 } 754 755 /* 756 * encrypted_init - initialize an encrypted key 757 * 758 * For a new key, use a random number for both the iv and data 759 * itself. For an old key, decrypt the hex encoded data. 760 */ 761 static int encrypted_init(struct encrypted_key_payload *epayload, 762 const char *key_desc, const char *format, 763 const char *master_desc, const char *datalen, 764 const char *hex_encoded_iv) 765 { 766 int ret = 0; 767 768 if (format && !strcmp(format, key_format_ecryptfs)) { 769 ret = valid_ecryptfs_desc(key_desc); 770 if (ret < 0) 771 return ret; 772 773 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, 774 key_desc); 775 } 776 777 __ekey_init(epayload, format, master_desc, datalen); 778 if (!hex_encoded_iv) { 779 get_random_bytes(epayload->iv, ivsize); 780 781 get_random_bytes(epayload->decrypted_data, 782 epayload->decrypted_datalen); 783 } else 784 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); 785 return ret; 786 } 787 788 /* 789 * encrypted_instantiate - instantiate an encrypted key 790 * 791 * Decrypt an existing encrypted datablob or create a new encrypted key 792 * based on a kernel random number. 793 * 794 * On success, return 0. Otherwise return errno. 795 */ 796 static int encrypted_instantiate(struct key *key, 797 struct key_preparsed_payload *prep) 798 { 799 struct encrypted_key_payload *epayload = NULL; 800 char *datablob = NULL; 801 const char *format = NULL; 802 char *master_desc = NULL; 803 char *decrypted_datalen = NULL; 804 char *hex_encoded_iv = NULL; 805 size_t datalen = prep->datalen; 806 int ret; 807 808 if (datalen <= 0 || datalen > 32767 || !prep->data) 809 return -EINVAL; 810 811 datablob = kmalloc(datalen + 1, GFP_KERNEL); 812 if (!datablob) 813 return -ENOMEM; 814 datablob[datalen] = 0; 815 memcpy(datablob, prep->data, datalen); 816 ret = datablob_parse(datablob, &format, &master_desc, 817 &decrypted_datalen, &hex_encoded_iv); 818 if (ret < 0) 819 goto out; 820 821 epayload = encrypted_key_alloc(key, format, master_desc, 822 decrypted_datalen); 823 if (IS_ERR(epayload)) { 824 ret = PTR_ERR(epayload); 825 goto out; 826 } 827 ret = encrypted_init(epayload, key->description, format, master_desc, 828 decrypted_datalen, hex_encoded_iv); 829 if (ret < 0) { 830 kzfree(epayload); 831 goto out; 832 } 833 834 rcu_assign_keypointer(key, epayload); 835 out: 836 kzfree(datablob); 837 return ret; 838 } 839 840 static void encrypted_rcu_free(struct rcu_head *rcu) 841 { 842 struct encrypted_key_payload *epayload; 843 844 epayload = container_of(rcu, struct encrypted_key_payload, rcu); 845 kzfree(epayload); 846 } 847 848 /* 849 * encrypted_update - update the master key description 850 * 851 * Change the master key description for an existing encrypted key. 852 * The next read will return an encrypted datablob using the new 853 * master key description. 854 * 855 * On success, return 0. Otherwise return errno. 856 */ 857 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) 858 { 859 struct encrypted_key_payload *epayload = key->payload.data[0]; 860 struct encrypted_key_payload *new_epayload; 861 char *buf; 862 char *new_master_desc = NULL; 863 const char *format = NULL; 864 size_t datalen = prep->datalen; 865 int ret = 0; 866 867 if (key_is_negative(key)) 868 return -ENOKEY; 869 if (datalen <= 0 || datalen > 32767 || !prep->data) 870 return -EINVAL; 871 872 buf = kmalloc(datalen + 1, GFP_KERNEL); 873 if (!buf) 874 return -ENOMEM; 875 876 buf[datalen] = 0; 877 memcpy(buf, prep->data, datalen); 878 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); 879 if (ret < 0) 880 goto out; 881 882 ret = valid_master_desc(new_master_desc, epayload->master_desc); 883 if (ret < 0) 884 goto out; 885 886 new_epayload = encrypted_key_alloc(key, epayload->format, 887 new_master_desc, epayload->datalen); 888 if (IS_ERR(new_epayload)) { 889 ret = PTR_ERR(new_epayload); 890 goto out; 891 } 892 893 __ekey_init(new_epayload, epayload->format, new_master_desc, 894 epayload->datalen); 895 896 memcpy(new_epayload->iv, epayload->iv, ivsize); 897 memcpy(new_epayload->payload_data, epayload->payload_data, 898 epayload->payload_datalen); 899 900 rcu_assign_keypointer(key, new_epayload); 901 call_rcu(&epayload->rcu, encrypted_rcu_free); 902 out: 903 kzfree(buf); 904 return ret; 905 } 906 907 /* 908 * encrypted_read - format and copy the encrypted data to userspace 909 * 910 * The resulting datablob format is: 911 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> 912 * 913 * On success, return to userspace the encrypted key datablob size. 914 */ 915 static long encrypted_read(const struct key *key, char __user *buffer, 916 size_t buflen) 917 { 918 struct encrypted_key_payload *epayload; 919 struct key *mkey; 920 const u8 *master_key; 921 size_t master_keylen; 922 char derived_key[HASH_SIZE]; 923 char *ascii_buf; 924 size_t asciiblob_len; 925 int ret; 926 927 epayload = dereference_key_locked(key); 928 929 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ 930 asciiblob_len = epayload->datablob_len + ivsize + 1 931 + roundup(epayload->decrypted_datalen, blksize) 932 + (HASH_SIZE * 2); 933 934 if (!buffer || buflen < asciiblob_len) 935 return asciiblob_len; 936 937 mkey = request_master_key(epayload, &master_key, &master_keylen); 938 if (IS_ERR(mkey)) 939 return PTR_ERR(mkey); 940 941 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 942 if (ret < 0) 943 goto out; 944 945 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); 946 if (ret < 0) 947 goto out; 948 949 ret = datablob_hmac_append(epayload, master_key, master_keylen); 950 if (ret < 0) 951 goto out; 952 953 ascii_buf = datablob_format(epayload, asciiblob_len); 954 if (!ascii_buf) { 955 ret = -ENOMEM; 956 goto out; 957 } 958 959 up_read(&mkey->sem); 960 key_put(mkey); 961 memzero_explicit(derived_key, sizeof(derived_key)); 962 963 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) 964 ret = -EFAULT; 965 kzfree(ascii_buf); 966 967 return asciiblob_len; 968 out: 969 up_read(&mkey->sem); 970 key_put(mkey); 971 memzero_explicit(derived_key, sizeof(derived_key)); 972 return ret; 973 } 974 975 /* 976 * encrypted_destroy - clear and free the key's payload 977 */ 978 static void encrypted_destroy(struct key *key) 979 { 980 kzfree(key->payload.data[0]); 981 } 982 983 struct key_type key_type_encrypted = { 984 .name = "encrypted", 985 .instantiate = encrypted_instantiate, 986 .update = encrypted_update, 987 .destroy = encrypted_destroy, 988 .describe = user_describe, 989 .read = encrypted_read, 990 }; 991 EXPORT_SYMBOL_GPL(key_type_encrypted); 992 993 static int __init init_encrypted(void) 994 { 995 int ret; 996 997 hash_tfm = crypto_alloc_shash(hash_alg, 0, 0); 998 if (IS_ERR(hash_tfm)) { 999 pr_err("encrypted_key: can't allocate %s transform: %ld\n", 1000 hash_alg, PTR_ERR(hash_tfm)); 1001 return PTR_ERR(hash_tfm); 1002 } 1003 1004 ret = aes_get_sizes(); 1005 if (ret < 0) 1006 goto out; 1007 ret = register_key_type(&key_type_encrypted); 1008 if (ret < 0) 1009 goto out; 1010 return 0; 1011 out: 1012 crypto_free_shash(hash_tfm); 1013 return ret; 1014 1015 } 1016 1017 static void __exit cleanup_encrypted(void) 1018 { 1019 crypto_free_shash(hash_tfm); 1020 unregister_key_type(&key_type_encrypted); 1021 } 1022 1023 late_initcall(init_encrypted); 1024 module_exit(cleanup_encrypted); 1025 1026 MODULE_LICENSE("GPL"); 1027