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/crypto.h> 32 #include <linux/ctype.h> 33 #include <crypto/hash.h> 34 #include <crypto/sha.h> 35 #include <crypto/aes.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_blkcipher *tfm; 89 90 tfm = crypto_alloc_blkcipher(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_blkcipher_ivsize(tfm); 97 blksize = crypto_blkcipher_blocksize(tfm); 98 crypto_free_blkcipher(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, u8 **master_key, 307 size_t *master_keylen) 308 { 309 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 = ukey->payload.data; 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 int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key, 405 unsigned int key_len, const u8 *iv, 406 unsigned int ivsize) 407 { 408 int ret; 409 410 desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 411 if (IS_ERR(desc->tfm)) { 412 pr_err("encrypted_key: failed to load %s transform (%ld)\n", 413 blkcipher_alg, PTR_ERR(desc->tfm)); 414 return PTR_ERR(desc->tfm); 415 } 416 desc->flags = 0; 417 418 ret = crypto_blkcipher_setkey(desc->tfm, key, key_len); 419 if (ret < 0) { 420 pr_err("encrypted_key: failed to setkey (%d)\n", ret); 421 crypto_free_blkcipher(desc->tfm); 422 return ret; 423 } 424 crypto_blkcipher_set_iv(desc->tfm, iv, ivsize); 425 return 0; 426 } 427 428 static struct key *request_master_key(struct encrypted_key_payload *epayload, 429 u8 **master_key, size_t *master_keylen) 430 { 431 struct key *mkey = NULL; 432 433 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, 434 KEY_TRUSTED_PREFIX_LEN)) { 435 mkey = request_trusted_key(epayload->master_desc + 436 KEY_TRUSTED_PREFIX_LEN, 437 master_key, master_keylen); 438 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, 439 KEY_USER_PREFIX_LEN)) { 440 mkey = request_user_key(epayload->master_desc + 441 KEY_USER_PREFIX_LEN, 442 master_key, master_keylen); 443 } else 444 goto out; 445 446 if (IS_ERR(mkey)) { 447 int ret = PTR_ERR(mkey); 448 449 if (ret == -ENOTSUPP) 450 pr_info("encrypted_key: key %s not supported", 451 epayload->master_desc); 452 else 453 pr_info("encrypted_key: key %s not found", 454 epayload->master_desc); 455 goto out; 456 } 457 458 dump_master_key(*master_key, *master_keylen); 459 out: 460 return mkey; 461 } 462 463 /* Before returning data to userspace, encrypt decrypted data. */ 464 static int derived_key_encrypt(struct encrypted_key_payload *epayload, 465 const u8 *derived_key, 466 unsigned int derived_keylen) 467 { 468 struct scatterlist sg_in[2]; 469 struct scatterlist sg_out[1]; 470 struct blkcipher_desc desc; 471 unsigned int encrypted_datalen; 472 unsigned int padlen; 473 char pad[16]; 474 int ret; 475 476 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 477 padlen = encrypted_datalen - epayload->decrypted_datalen; 478 479 ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, 480 epayload->iv, ivsize); 481 if (ret < 0) 482 goto out; 483 dump_decrypted_data(epayload); 484 485 memset(pad, 0, sizeof pad); 486 sg_init_table(sg_in, 2); 487 sg_set_buf(&sg_in[0], epayload->decrypted_data, 488 epayload->decrypted_datalen); 489 sg_set_buf(&sg_in[1], pad, padlen); 490 491 sg_init_table(sg_out, 1); 492 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); 493 494 ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen); 495 crypto_free_blkcipher(desc.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 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 = memcmp(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 return ret; 560 } 561 562 static int derived_key_decrypt(struct encrypted_key_payload *epayload, 563 const u8 *derived_key, 564 unsigned int derived_keylen) 565 { 566 struct scatterlist sg_in[1]; 567 struct scatterlist sg_out[2]; 568 struct blkcipher_desc desc; 569 unsigned int encrypted_datalen; 570 char pad[16]; 571 int ret; 572 573 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 574 ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, 575 epayload->iv, ivsize); 576 if (ret < 0) 577 goto out; 578 dump_encrypted_data(epayload, encrypted_datalen); 579 580 memset(pad, 0, sizeof pad); 581 sg_init_table(sg_in, 1); 582 sg_init_table(sg_out, 2); 583 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); 584 sg_set_buf(&sg_out[0], epayload->decrypted_data, 585 epayload->decrypted_datalen); 586 sg_set_buf(&sg_out[1], pad, sizeof pad); 587 588 ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen); 589 crypto_free_blkcipher(desc.tfm); 590 if (ret < 0) 591 goto out; 592 dump_decrypted_data(epayload); 593 out: 594 return ret; 595 } 596 597 /* Allocate memory for decrypted key and datablob. */ 598 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, 599 const char *format, 600 const char *master_desc, 601 const char *datalen) 602 { 603 struct encrypted_key_payload *epayload = NULL; 604 unsigned short datablob_len; 605 unsigned short decrypted_datalen; 606 unsigned short payload_datalen; 607 unsigned int encrypted_datalen; 608 unsigned int format_len; 609 long dlen; 610 int ret; 611 612 ret = kstrtol(datalen, 10, &dlen); 613 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) 614 return ERR_PTR(-EINVAL); 615 616 format_len = (!format) ? strlen(key_format_default) : strlen(format); 617 decrypted_datalen = dlen; 618 payload_datalen = decrypted_datalen; 619 if (format && !strcmp(format, key_format_ecryptfs)) { 620 if (dlen != ECRYPTFS_MAX_KEY_BYTES) { 621 pr_err("encrypted_key: keylen for the ecryptfs format " 622 "must be equal to %d bytes\n", 623 ECRYPTFS_MAX_KEY_BYTES); 624 return ERR_PTR(-EINVAL); 625 } 626 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; 627 payload_datalen = sizeof(struct ecryptfs_auth_tok); 628 } 629 630 encrypted_datalen = roundup(decrypted_datalen, blksize); 631 632 datablob_len = format_len + 1 + strlen(master_desc) + 1 633 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; 634 635 ret = key_payload_reserve(key, payload_datalen + datablob_len 636 + HASH_SIZE + 1); 637 if (ret < 0) 638 return ERR_PTR(ret); 639 640 epayload = kzalloc(sizeof(*epayload) + payload_datalen + 641 datablob_len + HASH_SIZE + 1, GFP_KERNEL); 642 if (!epayload) 643 return ERR_PTR(-ENOMEM); 644 645 epayload->payload_datalen = payload_datalen; 646 epayload->decrypted_datalen = decrypted_datalen; 647 epayload->datablob_len = datablob_len; 648 return epayload; 649 } 650 651 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, 652 const char *format, const char *hex_encoded_iv) 653 { 654 struct key *mkey; 655 u8 derived_key[HASH_SIZE]; 656 u8 *master_key; 657 u8 *hmac; 658 const char *hex_encoded_data; 659 unsigned int encrypted_datalen; 660 size_t master_keylen; 661 size_t asciilen; 662 int ret; 663 664 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 665 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; 666 if (strlen(hex_encoded_iv) != asciilen) 667 return -EINVAL; 668 669 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; 670 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); 671 if (ret < 0) 672 return -EINVAL; 673 ret = hex2bin(epayload->encrypted_data, hex_encoded_data, 674 encrypted_datalen); 675 if (ret < 0) 676 return -EINVAL; 677 678 hmac = epayload->format + epayload->datablob_len; 679 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), 680 HASH_SIZE); 681 if (ret < 0) 682 return -EINVAL; 683 684 mkey = request_master_key(epayload, &master_key, &master_keylen); 685 if (IS_ERR(mkey)) 686 return PTR_ERR(mkey); 687 688 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); 689 if (ret < 0) { 690 pr_err("encrypted_key: bad hmac (%d)\n", ret); 691 goto out; 692 } 693 694 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 695 if (ret < 0) 696 goto out; 697 698 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); 699 if (ret < 0) 700 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); 701 out: 702 up_read(&mkey->sem); 703 key_put(mkey); 704 return ret; 705 } 706 707 static void __ekey_init(struct encrypted_key_payload *epayload, 708 const char *format, const char *master_desc, 709 const char *datalen) 710 { 711 unsigned int format_len; 712 713 format_len = (!format) ? strlen(key_format_default) : strlen(format); 714 epayload->format = epayload->payload_data + epayload->payload_datalen; 715 epayload->master_desc = epayload->format + format_len + 1; 716 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; 717 epayload->iv = epayload->datalen + strlen(datalen) + 1; 718 epayload->encrypted_data = epayload->iv + ivsize + 1; 719 epayload->decrypted_data = epayload->payload_data; 720 721 if (!format) 722 memcpy(epayload->format, key_format_default, format_len); 723 else { 724 if (!strcmp(format, key_format_ecryptfs)) 725 epayload->decrypted_data = 726 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); 727 728 memcpy(epayload->format, format, format_len); 729 } 730 731 memcpy(epayload->master_desc, master_desc, strlen(master_desc)); 732 memcpy(epayload->datalen, datalen, strlen(datalen)); 733 } 734 735 /* 736 * encrypted_init - initialize an encrypted key 737 * 738 * For a new key, use a random number for both the iv and data 739 * itself. For an old key, decrypt the hex encoded data. 740 */ 741 static int encrypted_init(struct encrypted_key_payload *epayload, 742 const char *key_desc, const char *format, 743 const char *master_desc, const char *datalen, 744 const char *hex_encoded_iv) 745 { 746 int ret = 0; 747 748 if (format && !strcmp(format, key_format_ecryptfs)) { 749 ret = valid_ecryptfs_desc(key_desc); 750 if (ret < 0) 751 return ret; 752 753 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, 754 key_desc); 755 } 756 757 __ekey_init(epayload, format, master_desc, datalen); 758 if (!hex_encoded_iv) { 759 get_random_bytes(epayload->iv, ivsize); 760 761 get_random_bytes(epayload->decrypted_data, 762 epayload->decrypted_datalen); 763 } else 764 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); 765 return ret; 766 } 767 768 /* 769 * encrypted_instantiate - instantiate an encrypted key 770 * 771 * Decrypt an existing encrypted datablob or create a new encrypted key 772 * based on a kernel random number. 773 * 774 * On success, return 0. Otherwise return errno. 775 */ 776 static int encrypted_instantiate(struct key *key, 777 struct key_preparsed_payload *prep) 778 { 779 struct encrypted_key_payload *epayload = NULL; 780 char *datablob = NULL; 781 const char *format = NULL; 782 char *master_desc = NULL; 783 char *decrypted_datalen = NULL; 784 char *hex_encoded_iv = NULL; 785 size_t datalen = prep->datalen; 786 int ret; 787 788 if (datalen <= 0 || datalen > 32767 || !prep->data) 789 return -EINVAL; 790 791 datablob = kmalloc(datalen + 1, GFP_KERNEL); 792 if (!datablob) 793 return -ENOMEM; 794 datablob[datalen] = 0; 795 memcpy(datablob, prep->data, datalen); 796 ret = datablob_parse(datablob, &format, &master_desc, 797 &decrypted_datalen, &hex_encoded_iv); 798 if (ret < 0) 799 goto out; 800 801 epayload = encrypted_key_alloc(key, format, master_desc, 802 decrypted_datalen); 803 if (IS_ERR(epayload)) { 804 ret = PTR_ERR(epayload); 805 goto out; 806 } 807 ret = encrypted_init(epayload, key->description, format, master_desc, 808 decrypted_datalen, hex_encoded_iv); 809 if (ret < 0) { 810 kfree(epayload); 811 goto out; 812 } 813 814 rcu_assign_keypointer(key, epayload); 815 out: 816 kfree(datablob); 817 return ret; 818 } 819 820 static void encrypted_rcu_free(struct rcu_head *rcu) 821 { 822 struct encrypted_key_payload *epayload; 823 824 epayload = container_of(rcu, struct encrypted_key_payload, rcu); 825 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); 826 kfree(epayload); 827 } 828 829 /* 830 * encrypted_update - update the master key description 831 * 832 * Change the master key description for an existing encrypted key. 833 * The next read will return an encrypted datablob using the new 834 * master key description. 835 * 836 * On success, return 0. Otherwise return errno. 837 */ 838 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) 839 { 840 struct encrypted_key_payload *epayload = key->payload.data; 841 struct encrypted_key_payload *new_epayload; 842 char *buf; 843 char *new_master_desc = NULL; 844 const char *format = NULL; 845 size_t datalen = prep->datalen; 846 int ret = 0; 847 848 if (datalen <= 0 || datalen > 32767 || !prep->data) 849 return -EINVAL; 850 851 buf = kmalloc(datalen + 1, GFP_KERNEL); 852 if (!buf) 853 return -ENOMEM; 854 855 buf[datalen] = 0; 856 memcpy(buf, prep->data, datalen); 857 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); 858 if (ret < 0) 859 goto out; 860 861 ret = valid_master_desc(new_master_desc, epayload->master_desc); 862 if (ret < 0) 863 goto out; 864 865 new_epayload = encrypted_key_alloc(key, epayload->format, 866 new_master_desc, epayload->datalen); 867 if (IS_ERR(new_epayload)) { 868 ret = PTR_ERR(new_epayload); 869 goto out; 870 } 871 872 __ekey_init(new_epayload, epayload->format, new_master_desc, 873 epayload->datalen); 874 875 memcpy(new_epayload->iv, epayload->iv, ivsize); 876 memcpy(new_epayload->payload_data, epayload->payload_data, 877 epayload->payload_datalen); 878 879 rcu_assign_keypointer(key, new_epayload); 880 call_rcu(&epayload->rcu, encrypted_rcu_free); 881 out: 882 kfree(buf); 883 return ret; 884 } 885 886 /* 887 * encrypted_read - format and copy the encrypted data to userspace 888 * 889 * The resulting datablob format is: 890 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> 891 * 892 * On success, return to userspace the encrypted key datablob size. 893 */ 894 static long encrypted_read(const struct key *key, char __user *buffer, 895 size_t buflen) 896 { 897 struct encrypted_key_payload *epayload; 898 struct key *mkey; 899 u8 *master_key; 900 size_t master_keylen; 901 char derived_key[HASH_SIZE]; 902 char *ascii_buf; 903 size_t asciiblob_len; 904 int ret; 905 906 epayload = rcu_dereference_key(key); 907 908 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ 909 asciiblob_len = epayload->datablob_len + ivsize + 1 910 + roundup(epayload->decrypted_datalen, blksize) 911 + (HASH_SIZE * 2); 912 913 if (!buffer || buflen < asciiblob_len) 914 return asciiblob_len; 915 916 mkey = request_master_key(epayload, &master_key, &master_keylen); 917 if (IS_ERR(mkey)) 918 return PTR_ERR(mkey); 919 920 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 921 if (ret < 0) 922 goto out; 923 924 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); 925 if (ret < 0) 926 goto out; 927 928 ret = datablob_hmac_append(epayload, master_key, master_keylen); 929 if (ret < 0) 930 goto out; 931 932 ascii_buf = datablob_format(epayload, asciiblob_len); 933 if (!ascii_buf) { 934 ret = -ENOMEM; 935 goto out; 936 } 937 938 up_read(&mkey->sem); 939 key_put(mkey); 940 941 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) 942 ret = -EFAULT; 943 kfree(ascii_buf); 944 945 return asciiblob_len; 946 out: 947 up_read(&mkey->sem); 948 key_put(mkey); 949 return ret; 950 } 951 952 /* 953 * encrypted_destroy - before freeing the key, clear the decrypted data 954 * 955 * Before freeing the key, clear the memory containing the decrypted 956 * key data. 957 */ 958 static void encrypted_destroy(struct key *key) 959 { 960 struct encrypted_key_payload *epayload = key->payload.data; 961 962 if (!epayload) 963 return; 964 965 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); 966 kfree(key->payload.data); 967 } 968 969 struct key_type key_type_encrypted = { 970 .name = "encrypted", 971 .instantiate = encrypted_instantiate, 972 .update = encrypted_update, 973 .destroy = encrypted_destroy, 974 .describe = user_describe, 975 .read = encrypted_read, 976 }; 977 EXPORT_SYMBOL_GPL(key_type_encrypted); 978 979 static void encrypted_shash_release(void) 980 { 981 if (hashalg) 982 crypto_free_shash(hashalg); 983 if (hmacalg) 984 crypto_free_shash(hmacalg); 985 } 986 987 static int __init encrypted_shash_alloc(void) 988 { 989 int ret; 990 991 hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC); 992 if (IS_ERR(hmacalg)) { 993 pr_info("encrypted_key: could not allocate crypto %s\n", 994 hmac_alg); 995 return PTR_ERR(hmacalg); 996 } 997 998 hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC); 999 if (IS_ERR(hashalg)) { 1000 pr_info("encrypted_key: could not allocate crypto %s\n", 1001 hash_alg); 1002 ret = PTR_ERR(hashalg); 1003 goto hashalg_fail; 1004 } 1005 1006 return 0; 1007 1008 hashalg_fail: 1009 crypto_free_shash(hmacalg); 1010 return ret; 1011 } 1012 1013 static int __init init_encrypted(void) 1014 { 1015 int ret; 1016 1017 ret = encrypted_shash_alloc(); 1018 if (ret < 0) 1019 return ret; 1020 ret = register_key_type(&key_type_encrypted); 1021 if (ret < 0) 1022 goto out; 1023 return aes_get_sizes(); 1024 out: 1025 encrypted_shash_release(); 1026 return ret; 1027 1028 } 1029 1030 static void __exit cleanup_encrypted(void) 1031 { 1032 encrypted_shash_release(); 1033 unregister_key_type(&key_type_encrypted); 1034 } 1035 1036 late_initcall(init_encrypted); 1037 module_exit(cleanup_encrypted); 1038 1039 MODULE_LICENSE("GPL"); 1040