1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2010 IBM Corporation 4 * Copyright (C) 2010 Politecnico di Torino, Italy 5 * TORSEC group -- http://security.polito.it 6 * 7 * Authors: 8 * Mimi Zohar <zohar@us.ibm.com> 9 * Roberto Sassu <roberto.sassu@polito.it> 10 * 11 * See Documentation/security/keys/trusted-encrypted.rst 12 */ 13 14 #include <linux/uaccess.h> 15 #include <linux/module.h> 16 #include <linux/init.h> 17 #include <linux/slab.h> 18 #include <linux/parser.h> 19 #include <linux/string.h> 20 #include <linux/err.h> 21 #include <keys/user-type.h> 22 #include <keys/trusted-type.h> 23 #include <keys/encrypted-type.h> 24 #include <linux/key-type.h> 25 #include <linux/random.h> 26 #include <linux/rcupdate.h> 27 #include <linux/scatterlist.h> 28 #include <linux/ctype.h> 29 #include <crypto/aes.h> 30 #include <crypto/algapi.h> 31 #include <crypto/hash.h> 32 #include <crypto/sha.h> 33 #include <crypto/skcipher.h> 34 35 #include "encrypted.h" 36 #include "ecryptfs_format.h" 37 38 static const char KEY_TRUSTED_PREFIX[] = "trusted:"; 39 static const char KEY_USER_PREFIX[] = "user:"; 40 static const char hash_alg[] = "sha256"; 41 static const char hmac_alg[] = "hmac(sha256)"; 42 static const char blkcipher_alg[] = "cbc(aes)"; 43 static const char key_format_default[] = "default"; 44 static const char key_format_ecryptfs[] = "ecryptfs"; 45 static const char key_format_enc32[] = "enc32"; 46 static unsigned int ivsize; 47 static int blksize; 48 49 #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) 50 #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) 51 #define KEY_ECRYPTFS_DESC_LEN 16 52 #define HASH_SIZE SHA256_DIGEST_SIZE 53 #define MAX_DATA_SIZE 4096 54 #define MIN_DATA_SIZE 20 55 #define KEY_ENC32_PAYLOAD_LEN 32 56 57 static struct crypto_shash *hash_tfm; 58 59 enum { 60 Opt_new, Opt_load, Opt_update, Opt_err 61 }; 62 63 enum { 64 Opt_default, Opt_ecryptfs, Opt_enc32, Opt_error 65 }; 66 67 static const match_table_t key_format_tokens = { 68 {Opt_default, "default"}, 69 {Opt_ecryptfs, "ecryptfs"}, 70 {Opt_enc32, "enc32"}, 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_enc32: 199 case Opt_default: 200 *format = p; 201 *master_desc = strsep(&datablob, " \t"); 202 break; 203 case Opt_error: 204 *master_desc = p; 205 break; 206 } 207 208 if (!*master_desc) { 209 pr_info("encrypted_key: master key parameter is missing\n"); 210 goto out; 211 } 212 213 if (valid_master_desc(*master_desc, NULL) < 0) { 214 pr_info("encrypted_key: master key parameter \'%s\' " 215 "is invalid\n", *master_desc); 216 goto out; 217 } 218 219 if (decrypted_datalen) { 220 *decrypted_datalen = strsep(&datablob, " \t"); 221 if (!*decrypted_datalen) { 222 pr_info("encrypted_key: keylen parameter is missing\n"); 223 goto out; 224 } 225 } 226 227 switch (key_cmd) { 228 case Opt_new: 229 if (!decrypted_datalen) { 230 pr_info("encrypted_key: keyword \'%s\' not allowed " 231 "when called from .update method\n", keyword); 232 break; 233 } 234 ret = 0; 235 break; 236 case Opt_load: 237 if (!decrypted_datalen) { 238 pr_info("encrypted_key: keyword \'%s\' not allowed " 239 "when called from .update method\n", keyword); 240 break; 241 } 242 *hex_encoded_iv = strsep(&datablob, " \t"); 243 if (!*hex_encoded_iv) { 244 pr_info("encrypted_key: hex blob is missing\n"); 245 break; 246 } 247 ret = 0; 248 break; 249 case Opt_update: 250 if (decrypted_datalen) { 251 pr_info("encrypted_key: keyword \'%s\' not allowed " 252 "when called from .instantiate method\n", 253 keyword); 254 break; 255 } 256 ret = 0; 257 break; 258 case Opt_err: 259 pr_info("encrypted_key: keyword \'%s\' not recognized\n", 260 keyword); 261 break; 262 } 263 out: 264 return ret; 265 } 266 267 /* 268 * datablob_format - format as an ascii string, before copying to userspace 269 */ 270 static char *datablob_format(struct encrypted_key_payload *epayload, 271 size_t asciiblob_len) 272 { 273 char *ascii_buf, *bufp; 274 u8 *iv = epayload->iv; 275 int len; 276 int i; 277 278 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); 279 if (!ascii_buf) 280 goto out; 281 282 ascii_buf[asciiblob_len] = '\0'; 283 284 /* copy datablob master_desc and datalen strings */ 285 len = sprintf(ascii_buf, "%s %s %s ", epayload->format, 286 epayload->master_desc, epayload->datalen); 287 288 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ 289 bufp = &ascii_buf[len]; 290 for (i = 0; i < (asciiblob_len - len) / 2; i++) 291 bufp = hex_byte_pack(bufp, iv[i]); 292 out: 293 return ascii_buf; 294 } 295 296 /* 297 * request_user_key - request the user key 298 * 299 * Use a user provided key to encrypt/decrypt an encrypted-key. 300 */ 301 static struct key *request_user_key(const char *master_desc, const u8 **master_key, 302 size_t *master_keylen) 303 { 304 const struct user_key_payload *upayload; 305 struct key *ukey; 306 307 ukey = request_key(&key_type_user, master_desc, NULL); 308 if (IS_ERR(ukey)) 309 goto error; 310 311 down_read(&ukey->sem); 312 upayload = user_key_payload_locked(ukey); 313 if (!upayload) { 314 /* key was revoked before we acquired its semaphore */ 315 up_read(&ukey->sem); 316 key_put(ukey); 317 ukey = ERR_PTR(-EKEYREVOKED); 318 goto error; 319 } 320 *master_key = upayload->data; 321 *master_keylen = upayload->datalen; 322 error: 323 return ukey; 324 } 325 326 static int calc_hash(struct crypto_shash *tfm, u8 *digest, 327 const u8 *buf, unsigned int buflen) 328 { 329 SHASH_DESC_ON_STACK(desc, tfm); 330 int err; 331 332 desc->tfm = tfm; 333 334 err = crypto_shash_digest(desc, buf, buflen, digest); 335 shash_desc_zero(desc); 336 return err; 337 } 338 339 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, 340 const u8 *buf, unsigned int buflen) 341 { 342 struct crypto_shash *tfm; 343 int err; 344 345 tfm = crypto_alloc_shash(hmac_alg, 0, 0); 346 if (IS_ERR(tfm)) { 347 pr_err("encrypted_key: can't alloc %s transform: %ld\n", 348 hmac_alg, PTR_ERR(tfm)); 349 return PTR_ERR(tfm); 350 } 351 352 err = crypto_shash_setkey(tfm, key, keylen); 353 if (!err) 354 err = calc_hash(tfm, digest, buf, buflen); 355 crypto_free_shash(tfm); 356 return err; 357 } 358 359 enum derived_key_type { ENC_KEY, AUTH_KEY }; 360 361 /* Derive authentication/encryption key from trusted key */ 362 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, 363 const u8 *master_key, size_t master_keylen) 364 { 365 u8 *derived_buf; 366 unsigned int derived_buf_len; 367 int ret; 368 369 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; 370 if (derived_buf_len < HASH_SIZE) 371 derived_buf_len = HASH_SIZE; 372 373 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); 374 if (!derived_buf) 375 return -ENOMEM; 376 377 if (key_type) 378 strcpy(derived_buf, "AUTH_KEY"); 379 else 380 strcpy(derived_buf, "ENC_KEY"); 381 382 memcpy(derived_buf + strlen(derived_buf) + 1, master_key, 383 master_keylen); 384 ret = calc_hash(hash_tfm, derived_key, derived_buf, derived_buf_len); 385 kzfree(derived_buf); 386 return ret; 387 } 388 389 static struct skcipher_request *init_skcipher_req(const u8 *key, 390 unsigned int key_len) 391 { 392 struct skcipher_request *req; 393 struct crypto_skcipher *tfm; 394 int ret; 395 396 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 397 if (IS_ERR(tfm)) { 398 pr_err("encrypted_key: failed to load %s transform (%ld)\n", 399 blkcipher_alg, PTR_ERR(tfm)); 400 return ERR_CAST(tfm); 401 } 402 403 ret = crypto_skcipher_setkey(tfm, key, key_len); 404 if (ret < 0) { 405 pr_err("encrypted_key: failed to setkey (%d)\n", ret); 406 crypto_free_skcipher(tfm); 407 return ERR_PTR(ret); 408 } 409 410 req = skcipher_request_alloc(tfm, GFP_KERNEL); 411 if (!req) { 412 pr_err("encrypted_key: failed to allocate request for %s\n", 413 blkcipher_alg); 414 crypto_free_skcipher(tfm); 415 return ERR_PTR(-ENOMEM); 416 } 417 418 skcipher_request_set_callback(req, 0, NULL, NULL); 419 return req; 420 } 421 422 static struct key *request_master_key(struct encrypted_key_payload *epayload, 423 const u8 **master_key, size_t *master_keylen) 424 { 425 struct key *mkey = ERR_PTR(-EINVAL); 426 427 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, 428 KEY_TRUSTED_PREFIX_LEN)) { 429 mkey = request_trusted_key(epayload->master_desc + 430 KEY_TRUSTED_PREFIX_LEN, 431 master_key, master_keylen); 432 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, 433 KEY_USER_PREFIX_LEN)) { 434 mkey = request_user_key(epayload->master_desc + 435 KEY_USER_PREFIX_LEN, 436 master_key, master_keylen); 437 } else 438 goto out; 439 440 if (IS_ERR(mkey)) { 441 int ret = PTR_ERR(mkey); 442 443 if (ret == -ENOTSUPP) 444 pr_info("encrypted_key: key %s not supported", 445 epayload->master_desc); 446 else 447 pr_info("encrypted_key: key %s not found", 448 epayload->master_desc); 449 goto out; 450 } 451 452 dump_master_key(*master_key, *master_keylen); 453 out: 454 return mkey; 455 } 456 457 /* Before returning data to userspace, encrypt decrypted data. */ 458 static int derived_key_encrypt(struct encrypted_key_payload *epayload, 459 const u8 *derived_key, 460 unsigned int derived_keylen) 461 { 462 struct scatterlist sg_in[2]; 463 struct scatterlist sg_out[1]; 464 struct crypto_skcipher *tfm; 465 struct skcipher_request *req; 466 unsigned int encrypted_datalen; 467 u8 iv[AES_BLOCK_SIZE]; 468 int ret; 469 470 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 471 472 req = init_skcipher_req(derived_key, derived_keylen); 473 ret = PTR_ERR(req); 474 if (IS_ERR(req)) 475 goto out; 476 dump_decrypted_data(epayload); 477 478 sg_init_table(sg_in, 2); 479 sg_set_buf(&sg_in[0], epayload->decrypted_data, 480 epayload->decrypted_datalen); 481 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0); 482 483 sg_init_table(sg_out, 1); 484 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); 485 486 memcpy(iv, epayload->iv, sizeof(iv)); 487 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 488 ret = crypto_skcipher_encrypt(req); 489 tfm = crypto_skcipher_reqtfm(req); 490 skcipher_request_free(req); 491 crypto_free_skcipher(tfm); 492 if (ret < 0) 493 pr_err("encrypted_key: failed to encrypt (%d)\n", ret); 494 else 495 dump_encrypted_data(epayload, encrypted_datalen); 496 out: 497 return ret; 498 } 499 500 static int datablob_hmac_append(struct encrypted_key_payload *epayload, 501 const u8 *master_key, size_t master_keylen) 502 { 503 u8 derived_key[HASH_SIZE]; 504 u8 *digest; 505 int ret; 506 507 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 508 if (ret < 0) 509 goto out; 510 511 digest = epayload->format + epayload->datablob_len; 512 ret = calc_hmac(digest, derived_key, sizeof derived_key, 513 epayload->format, epayload->datablob_len); 514 if (!ret) 515 dump_hmac(NULL, digest, HASH_SIZE); 516 out: 517 memzero_explicit(derived_key, sizeof(derived_key)); 518 return ret; 519 } 520 521 /* verify HMAC before decrypting encrypted key */ 522 static int datablob_hmac_verify(struct encrypted_key_payload *epayload, 523 const u8 *format, const u8 *master_key, 524 size_t master_keylen) 525 { 526 u8 derived_key[HASH_SIZE]; 527 u8 digest[HASH_SIZE]; 528 int ret; 529 char *p; 530 unsigned short len; 531 532 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 533 if (ret < 0) 534 goto out; 535 536 len = epayload->datablob_len; 537 if (!format) { 538 p = epayload->master_desc; 539 len -= strlen(epayload->format) + 1; 540 } else 541 p = epayload->format; 542 543 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); 544 if (ret < 0) 545 goto out; 546 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len, 547 sizeof(digest)); 548 if (ret) { 549 ret = -EINVAL; 550 dump_hmac("datablob", 551 epayload->format + epayload->datablob_len, 552 HASH_SIZE); 553 dump_hmac("calc", digest, HASH_SIZE); 554 } 555 out: 556 memzero_explicit(derived_key, sizeof(derived_key)); 557 return ret; 558 } 559 560 static int derived_key_decrypt(struct encrypted_key_payload *epayload, 561 const u8 *derived_key, 562 unsigned int derived_keylen) 563 { 564 struct scatterlist sg_in[1]; 565 struct scatterlist sg_out[2]; 566 struct crypto_skcipher *tfm; 567 struct skcipher_request *req; 568 unsigned int encrypted_datalen; 569 u8 iv[AES_BLOCK_SIZE]; 570 u8 *pad; 571 int ret; 572 573 /* Throwaway buffer to hold the unused zero padding at the end */ 574 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL); 575 if (!pad) 576 return -ENOMEM; 577 578 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 579 req = init_skcipher_req(derived_key, derived_keylen); 580 ret = PTR_ERR(req); 581 if (IS_ERR(req)) 582 goto out; 583 dump_encrypted_data(epayload, encrypted_datalen); 584 585 sg_init_table(sg_in, 1); 586 sg_init_table(sg_out, 2); 587 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); 588 sg_set_buf(&sg_out[0], epayload->decrypted_data, 589 epayload->decrypted_datalen); 590 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE); 591 592 memcpy(iv, epayload->iv, sizeof(iv)); 593 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 594 ret = crypto_skcipher_decrypt(req); 595 tfm = crypto_skcipher_reqtfm(req); 596 skcipher_request_free(req); 597 crypto_free_skcipher(tfm); 598 if (ret < 0) 599 goto out; 600 dump_decrypted_data(epayload); 601 out: 602 kfree(pad); 603 return ret; 604 } 605 606 /* Allocate memory for decrypted key and datablob. */ 607 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, 608 const char *format, 609 const char *master_desc, 610 const char *datalen) 611 { 612 struct encrypted_key_payload *epayload = NULL; 613 unsigned short datablob_len; 614 unsigned short decrypted_datalen; 615 unsigned short payload_datalen; 616 unsigned int encrypted_datalen; 617 unsigned int format_len; 618 long dlen; 619 int ret; 620 621 ret = kstrtol(datalen, 10, &dlen); 622 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) 623 return ERR_PTR(-EINVAL); 624 625 format_len = (!format) ? strlen(key_format_default) : strlen(format); 626 decrypted_datalen = dlen; 627 payload_datalen = decrypted_datalen; 628 if (format) { 629 if (!strcmp(format, key_format_ecryptfs)) { 630 if (dlen != ECRYPTFS_MAX_KEY_BYTES) { 631 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n", 632 ECRYPTFS_MAX_KEY_BYTES); 633 return ERR_PTR(-EINVAL); 634 } 635 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; 636 payload_datalen = sizeof(struct ecryptfs_auth_tok); 637 } else if (!strcmp(format, key_format_enc32)) { 638 if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) { 639 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n", 640 decrypted_datalen); 641 return ERR_PTR(-EINVAL); 642 } 643 } 644 } 645 646 encrypted_datalen = roundup(decrypted_datalen, blksize); 647 648 datablob_len = format_len + 1 + strlen(master_desc) + 1 649 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; 650 651 ret = key_payload_reserve(key, payload_datalen + datablob_len 652 + HASH_SIZE + 1); 653 if (ret < 0) 654 return ERR_PTR(ret); 655 656 epayload = kzalloc(sizeof(*epayload) + payload_datalen + 657 datablob_len + HASH_SIZE + 1, GFP_KERNEL); 658 if (!epayload) 659 return ERR_PTR(-ENOMEM); 660 661 epayload->payload_datalen = payload_datalen; 662 epayload->decrypted_datalen = decrypted_datalen; 663 epayload->datablob_len = datablob_len; 664 return epayload; 665 } 666 667 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, 668 const char *format, const char *hex_encoded_iv) 669 { 670 struct key *mkey; 671 u8 derived_key[HASH_SIZE]; 672 const u8 *master_key; 673 u8 *hmac; 674 const char *hex_encoded_data; 675 unsigned int encrypted_datalen; 676 size_t master_keylen; 677 size_t asciilen; 678 int ret; 679 680 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 681 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; 682 if (strlen(hex_encoded_iv) != asciilen) 683 return -EINVAL; 684 685 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; 686 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); 687 if (ret < 0) 688 return -EINVAL; 689 ret = hex2bin(epayload->encrypted_data, hex_encoded_data, 690 encrypted_datalen); 691 if (ret < 0) 692 return -EINVAL; 693 694 hmac = epayload->format + epayload->datablob_len; 695 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), 696 HASH_SIZE); 697 if (ret < 0) 698 return -EINVAL; 699 700 mkey = request_master_key(epayload, &master_key, &master_keylen); 701 if (IS_ERR(mkey)) 702 return PTR_ERR(mkey); 703 704 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); 705 if (ret < 0) { 706 pr_err("encrypted_key: bad hmac (%d)\n", ret); 707 goto out; 708 } 709 710 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 711 if (ret < 0) 712 goto out; 713 714 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); 715 if (ret < 0) 716 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); 717 out: 718 up_read(&mkey->sem); 719 key_put(mkey); 720 memzero_explicit(derived_key, sizeof(derived_key)); 721 return ret; 722 } 723 724 static void __ekey_init(struct encrypted_key_payload *epayload, 725 const char *format, const char *master_desc, 726 const char *datalen) 727 { 728 unsigned int format_len; 729 730 format_len = (!format) ? strlen(key_format_default) : strlen(format); 731 epayload->format = epayload->payload_data + epayload->payload_datalen; 732 epayload->master_desc = epayload->format + format_len + 1; 733 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; 734 epayload->iv = epayload->datalen + strlen(datalen) + 1; 735 epayload->encrypted_data = epayload->iv + ivsize + 1; 736 epayload->decrypted_data = epayload->payload_data; 737 738 if (!format) 739 memcpy(epayload->format, key_format_default, format_len); 740 else { 741 if (!strcmp(format, key_format_ecryptfs)) 742 epayload->decrypted_data = 743 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); 744 745 memcpy(epayload->format, format, format_len); 746 } 747 748 memcpy(epayload->master_desc, master_desc, strlen(master_desc)); 749 memcpy(epayload->datalen, datalen, strlen(datalen)); 750 } 751 752 /* 753 * encrypted_init - initialize an encrypted key 754 * 755 * For a new key, use a random number for both the iv and data 756 * itself. For an old key, decrypt the hex encoded data. 757 */ 758 static int encrypted_init(struct encrypted_key_payload *epayload, 759 const char *key_desc, const char *format, 760 const char *master_desc, const char *datalen, 761 const char *hex_encoded_iv) 762 { 763 int ret = 0; 764 765 if (format && !strcmp(format, key_format_ecryptfs)) { 766 ret = valid_ecryptfs_desc(key_desc); 767 if (ret < 0) 768 return ret; 769 770 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, 771 key_desc); 772 } 773 774 __ekey_init(epayload, format, master_desc, datalen); 775 if (!hex_encoded_iv) { 776 get_random_bytes(epayload->iv, ivsize); 777 778 get_random_bytes(epayload->decrypted_data, 779 epayload->decrypted_datalen); 780 } else 781 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); 782 return ret; 783 } 784 785 /* 786 * encrypted_instantiate - instantiate an encrypted key 787 * 788 * Decrypt an existing encrypted datablob or create a new encrypted key 789 * based on a kernel random number. 790 * 791 * On success, return 0. Otherwise return errno. 792 */ 793 static int encrypted_instantiate(struct key *key, 794 struct key_preparsed_payload *prep) 795 { 796 struct encrypted_key_payload *epayload = NULL; 797 char *datablob = NULL; 798 const char *format = NULL; 799 char *master_desc = NULL; 800 char *decrypted_datalen = NULL; 801 char *hex_encoded_iv = NULL; 802 size_t datalen = prep->datalen; 803 int ret; 804 805 if (datalen <= 0 || datalen > 32767 || !prep->data) 806 return -EINVAL; 807 808 datablob = kmalloc(datalen + 1, GFP_KERNEL); 809 if (!datablob) 810 return -ENOMEM; 811 datablob[datalen] = 0; 812 memcpy(datablob, prep->data, datalen); 813 ret = datablob_parse(datablob, &format, &master_desc, 814 &decrypted_datalen, &hex_encoded_iv); 815 if (ret < 0) 816 goto out; 817 818 epayload = encrypted_key_alloc(key, format, master_desc, 819 decrypted_datalen); 820 if (IS_ERR(epayload)) { 821 ret = PTR_ERR(epayload); 822 goto out; 823 } 824 ret = encrypted_init(epayload, key->description, format, master_desc, 825 decrypted_datalen, hex_encoded_iv); 826 if (ret < 0) { 827 kzfree(epayload); 828 goto out; 829 } 830 831 rcu_assign_keypointer(key, epayload); 832 out: 833 kzfree(datablob); 834 return ret; 835 } 836 837 static void encrypted_rcu_free(struct rcu_head *rcu) 838 { 839 struct encrypted_key_payload *epayload; 840 841 epayload = container_of(rcu, struct encrypted_key_payload, rcu); 842 kzfree(epayload); 843 } 844 845 /* 846 * encrypted_update - update the master key description 847 * 848 * Change the master key description for an existing encrypted key. 849 * The next read will return an encrypted datablob using the new 850 * master key description. 851 * 852 * On success, return 0. Otherwise return errno. 853 */ 854 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) 855 { 856 struct encrypted_key_payload *epayload = key->payload.data[0]; 857 struct encrypted_key_payload *new_epayload; 858 char *buf; 859 char *new_master_desc = NULL; 860 const char *format = NULL; 861 size_t datalen = prep->datalen; 862 int ret = 0; 863 864 if (key_is_negative(key)) 865 return -ENOKEY; 866 if (datalen <= 0 || datalen > 32767 || !prep->data) 867 return -EINVAL; 868 869 buf = kmalloc(datalen + 1, GFP_KERNEL); 870 if (!buf) 871 return -ENOMEM; 872 873 buf[datalen] = 0; 874 memcpy(buf, prep->data, datalen); 875 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); 876 if (ret < 0) 877 goto out; 878 879 ret = valid_master_desc(new_master_desc, epayload->master_desc); 880 if (ret < 0) 881 goto out; 882 883 new_epayload = encrypted_key_alloc(key, epayload->format, 884 new_master_desc, epayload->datalen); 885 if (IS_ERR(new_epayload)) { 886 ret = PTR_ERR(new_epayload); 887 goto out; 888 } 889 890 __ekey_init(new_epayload, epayload->format, new_master_desc, 891 epayload->datalen); 892 893 memcpy(new_epayload->iv, epayload->iv, ivsize); 894 memcpy(new_epayload->payload_data, epayload->payload_data, 895 epayload->payload_datalen); 896 897 rcu_assign_keypointer(key, new_epayload); 898 call_rcu(&epayload->rcu, encrypted_rcu_free); 899 out: 900 kzfree(buf); 901 return ret; 902 } 903 904 /* 905 * encrypted_read - format and copy the encrypted data to userspace 906 * 907 * The resulting datablob format is: 908 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> 909 * 910 * On success, return to userspace the encrypted key datablob size. 911 */ 912 static long encrypted_read(const struct key *key, char __user *buffer, 913 size_t buflen) 914 { 915 struct encrypted_key_payload *epayload; 916 struct key *mkey; 917 const u8 *master_key; 918 size_t master_keylen; 919 char derived_key[HASH_SIZE]; 920 char *ascii_buf; 921 size_t asciiblob_len; 922 int ret; 923 924 epayload = dereference_key_locked(key); 925 926 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ 927 asciiblob_len = epayload->datablob_len + ivsize + 1 928 + roundup(epayload->decrypted_datalen, blksize) 929 + (HASH_SIZE * 2); 930 931 if (!buffer || buflen < asciiblob_len) 932 return asciiblob_len; 933 934 mkey = request_master_key(epayload, &master_key, &master_keylen); 935 if (IS_ERR(mkey)) 936 return PTR_ERR(mkey); 937 938 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 939 if (ret < 0) 940 goto out; 941 942 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); 943 if (ret < 0) 944 goto out; 945 946 ret = datablob_hmac_append(epayload, master_key, master_keylen); 947 if (ret < 0) 948 goto out; 949 950 ascii_buf = datablob_format(epayload, asciiblob_len); 951 if (!ascii_buf) { 952 ret = -ENOMEM; 953 goto out; 954 } 955 956 up_read(&mkey->sem); 957 key_put(mkey); 958 memzero_explicit(derived_key, sizeof(derived_key)); 959 960 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) 961 ret = -EFAULT; 962 kzfree(ascii_buf); 963 964 return asciiblob_len; 965 out: 966 up_read(&mkey->sem); 967 key_put(mkey); 968 memzero_explicit(derived_key, sizeof(derived_key)); 969 return ret; 970 } 971 972 /* 973 * encrypted_destroy - clear and free the key's payload 974 */ 975 static void encrypted_destroy(struct key *key) 976 { 977 kzfree(key->payload.data[0]); 978 } 979 980 struct key_type key_type_encrypted = { 981 .name = "encrypted", 982 .instantiate = encrypted_instantiate, 983 .update = encrypted_update, 984 .destroy = encrypted_destroy, 985 .describe = user_describe, 986 .read = encrypted_read, 987 }; 988 EXPORT_SYMBOL_GPL(key_type_encrypted); 989 990 static int __init init_encrypted(void) 991 { 992 int ret; 993 994 hash_tfm = crypto_alloc_shash(hash_alg, 0, 0); 995 if (IS_ERR(hash_tfm)) { 996 pr_err("encrypted_key: can't allocate %s transform: %ld\n", 997 hash_alg, PTR_ERR(hash_tfm)); 998 return PTR_ERR(hash_tfm); 999 } 1000 1001 ret = aes_get_sizes(); 1002 if (ret < 0) 1003 goto out; 1004 ret = register_key_type(&key_type_encrypted); 1005 if (ret < 0) 1006 goto out; 1007 return 0; 1008 out: 1009 crypto_free_shash(hash_tfm); 1010 return ret; 1011 1012 } 1013 1014 static void __exit cleanup_encrypted(void) 1015 { 1016 crypto_free_shash(hash_tfm); 1017 unregister_key_type(&key_type_encrypted); 1018 } 1019 1020 late_initcall(init_encrypted); 1021 module_exit(cleanup_encrypted); 1022 1023 MODULE_LICENSE("GPL"); 1024