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 -- https://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/hash.h> 31#include <crypto/sha2.h> 32#include <crypto/skcipher.h> 33#include <crypto/utils.h> 34 35#include "encrypted.h" 36#include "ecryptfs_format.h" 37 38static const char KEY_TRUSTED_PREFIX[] = "trusted:"; 39static const char KEY_USER_PREFIX[] = "user:"; 40static const char hash_alg[] = "sha256"; 41static const char hmac_alg[] = "hmac(sha256)"; 42static const char blkcipher_alg[] = "cbc(aes)"; 43static const char key_format_default[] = "default"; 44static const char key_format_ecryptfs[] = "ecryptfs"; 45static const char key_format_enc32[] = "enc32"; 46static unsigned int ivsize; 47static 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 57static struct crypto_shash *hash_tfm; 58 59enum { 60 Opt_new, Opt_load, Opt_update, Opt_err 61}; 62 63enum { 64 Opt_default, Opt_ecryptfs, Opt_enc32, Opt_error 65}; 66 67static 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 74static const match_table_t key_tokens = { 75 {Opt_new, "new"}, 76 {Opt_load, "load"}, 77 {Opt_update, "update"}, 78 {Opt_err, NULL} 79}; 80 81static bool user_decrypted_data = IS_ENABLED(CONFIG_USER_DECRYPTED_DATA); 82module_param(user_decrypted_data, bool, 0); 83MODULE_PARM_DESC(user_decrypted_data, 84 "Allow instantiation of encrypted keys using provided decrypted data"); 85 86static int aes_get_sizes(void) 87{ 88 struct crypto_skcipher *tfm; 89 90 tfm = crypto_alloc_skcipher(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_skcipher_ivsize(tfm); 97 blksize = crypto_skcipher_blocksize(tfm); 98 crypto_free_skcipher(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 */ 109static 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 */ 142static int valid_master_desc(const char *new_desc, const char *orig_desc) 143{ 144 int prefix_len; 145 146 if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) 147 prefix_len = KEY_TRUSTED_PREFIX_LEN; 148 else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) 149 prefix_len = KEY_USER_PREFIX_LEN; 150 else 151 return -EINVAL; 152 153 if (!new_desc[prefix_len]) 154 return -EINVAL; 155 156 if (orig_desc && strncmp(new_desc, orig_desc, prefix_len)) 157 return -EINVAL; 158 159 return 0; 160} 161 162/* 163 * datablob_parse - parse the keyctl data 164 * 165 * datablob format: 166 * new [<format>] <master-key name> <decrypted data length> [<decrypted data>] 167 * load [<format>] <master-key name> <decrypted data length> 168 * <encrypted iv + data> 169 * update <new-master-key name> 170 * 171 * Tokenizes a copy of the keyctl data, returning a pointer to each token, 172 * which is null terminated. 173 * 174 * On success returns 0, otherwise -EINVAL. 175 */ 176static int datablob_parse(char *datablob, const char **format, 177 char **master_desc, char **decrypted_datalen, 178 char **hex_encoded_iv, char **decrypted_data) 179{ 180 substring_t args[MAX_OPT_ARGS]; 181 int ret = -EINVAL; 182 int key_cmd; 183 int key_format; 184 char *p, *keyword; 185 186 keyword = strsep(&datablob, " \t"); 187 if (!keyword) { 188 pr_info("encrypted_key: insufficient parameters specified\n"); 189 return ret; 190 } 191 key_cmd = match_token(keyword, key_tokens, args); 192 193 /* Get optional format: default | ecryptfs */ 194 p = strsep(&datablob, " \t"); 195 if (!p) { 196 pr_err("encrypted_key: insufficient parameters specified\n"); 197 return ret; 198 } 199 200 key_format = match_token(p, key_format_tokens, args); 201 switch (key_format) { 202 case Opt_ecryptfs: 203 case Opt_enc32: 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 *decrypted_data = strsep(&datablob, " \t"); 240 ret = 0; 241 break; 242 case Opt_load: 243 if (!decrypted_datalen) { 244 pr_info("encrypted_key: keyword \'%s\' not allowed " 245 "when called from .update method\n", keyword); 246 break; 247 } 248 *hex_encoded_iv = strsep(&datablob, " \t"); 249 if (!*hex_encoded_iv) { 250 pr_info("encrypted_key: hex blob is missing\n"); 251 break; 252 } 253 ret = 0; 254 break; 255 case Opt_update: 256 if (decrypted_datalen) { 257 pr_info("encrypted_key: keyword \'%s\' not allowed " 258 "when called from .instantiate method\n", 259 keyword); 260 break; 261 } 262 ret = 0; 263 break; 264 case Opt_err: 265 pr_info("encrypted_key: keyword \'%s\' not recognized\n", 266 keyword); 267 break; 268 } 269out: 270 return ret; 271} 272 273/* 274 * datablob_format - format as an ascii string, before copying to userspace 275 */ 276static char *datablob_format(struct encrypted_key_payload *epayload, 277 size_t asciiblob_len) 278{ 279 char *ascii_buf, *bufp; 280 u8 *iv = epayload->iv; 281 int len; 282 int i; 283 284 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); 285 if (!ascii_buf) 286 goto out; 287 288 ascii_buf[asciiblob_len] = '\0'; 289 290 /* copy datablob master_desc and datalen strings */ 291 len = sprintf(ascii_buf, "%s %s %s ", epayload->format, 292 epayload->master_desc, epayload->datalen); 293 294 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ 295 bufp = &ascii_buf[len]; 296 for (i = 0; i < (asciiblob_len - len) / 2; i++) 297 bufp = hex_byte_pack(bufp, iv[i]); 298out: 299 return ascii_buf; 300} 301 302/* 303 * request_user_key - request the user key 304 * 305 * Use a user provided key to encrypt/decrypt an encrypted-key. 306 */ 307static struct key *request_user_key(const char *master_desc, const u8 **master_key, 308 size_t *master_keylen) 309{ 310 const struct user_key_payload *upayload; 311 struct key *ukey; 312 313 ukey = request_key(&key_type_user, master_desc, NULL); 314 if (IS_ERR(ukey)) 315 goto error; 316 317 down_read(&ukey->sem); 318 upayload = user_key_payload_locked(ukey); 319 if (!upayload) { 320 /* key was revoked before we acquired its semaphore */ 321 up_read(&ukey->sem); 322 key_put(ukey); 323 ukey = ERR_PTR(-EKEYREVOKED); 324 goto error; 325 } 326 *master_key = upayload->data; 327 *master_keylen = upayload->datalen; 328error: 329 return ukey; 330} 331 332static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, 333 const u8 *buf, unsigned int buflen) 334{ 335 struct crypto_shash *tfm; 336 int err; 337 338 tfm = crypto_alloc_shash(hmac_alg, 0, 0); 339 if (IS_ERR(tfm)) { 340 pr_err("encrypted_key: can't alloc %s transform: %ld\n", 341 hmac_alg, PTR_ERR(tfm)); 342 return PTR_ERR(tfm); 343 } 344 345 err = crypto_shash_setkey(tfm, key, keylen); 346 if (!err) 347 err = crypto_shash_tfm_digest(tfm, buf, buflen, digest); 348 crypto_free_shash(tfm); 349 return err; 350} 351 352enum derived_key_type { ENC_KEY, AUTH_KEY }; 353 354/* Derive authentication/encryption key from trusted key */ 355static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, 356 const u8 *master_key, size_t master_keylen) 357{ 358 u8 *derived_buf; 359 unsigned int derived_buf_len; 360 int ret; 361 362 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; 363 if (derived_buf_len < HASH_SIZE) 364 derived_buf_len = HASH_SIZE; 365 366 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); 367 if (!derived_buf) 368 return -ENOMEM; 369 370 if (key_type) 371 strcpy(derived_buf, "AUTH_KEY"); 372 else 373 strcpy(derived_buf, "ENC_KEY"); 374 375 memcpy(derived_buf + strlen(derived_buf) + 1, master_key, 376 master_keylen); 377 ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len, 378 derived_key); 379 kfree_sensitive(derived_buf); 380 return ret; 381} 382 383static struct skcipher_request *init_skcipher_req(const u8 *key, 384 unsigned int key_len) 385{ 386 struct skcipher_request *req; 387 struct crypto_skcipher *tfm; 388 int ret; 389 390 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 391 if (IS_ERR(tfm)) { 392 pr_err("encrypted_key: failed to load %s transform (%ld)\n", 393 blkcipher_alg, PTR_ERR(tfm)); 394 return ERR_CAST(tfm); 395 } 396 397 ret = crypto_skcipher_setkey(tfm, key, key_len); 398 if (ret < 0) { 399 pr_err("encrypted_key: failed to setkey (%d)\n", ret); 400 crypto_free_skcipher(tfm); 401 return ERR_PTR(ret); 402 } 403 404 req = skcipher_request_alloc(tfm, GFP_KERNEL); 405 if (!req) { 406 pr_err("encrypted_key: failed to allocate request for %s\n", 407 blkcipher_alg); 408 crypto_free_skcipher(tfm); 409 return ERR_PTR(-ENOMEM); 410 } 411 412 skcipher_request_set_callback(req, 0, NULL, NULL); 413 return req; 414} 415 416static struct key *request_master_key(struct encrypted_key_payload *epayload, 417 const u8 **master_key, size_t *master_keylen) 418{ 419 struct key *mkey = ERR_PTR(-EINVAL); 420 421 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, 422 KEY_TRUSTED_PREFIX_LEN)) { 423 mkey = request_trusted_key(epayload->master_desc + 424 KEY_TRUSTED_PREFIX_LEN, 425 master_key, master_keylen); 426 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, 427 KEY_USER_PREFIX_LEN)) { 428 mkey = request_user_key(epayload->master_desc + 429 KEY_USER_PREFIX_LEN, 430 master_key, master_keylen); 431 } else 432 goto out; 433 434 if (IS_ERR(mkey)) { 435 int ret = PTR_ERR(mkey); 436 437 if (ret == -ENOTSUPP) 438 pr_info("encrypted_key: key %s not supported", 439 epayload->master_desc); 440 else 441 pr_info("encrypted_key: key %s not found", 442 epayload->master_desc); 443 goto out; 444 } 445 446 dump_master_key(*master_key, *master_keylen); 447out: 448 return mkey; 449} 450 451/* Before returning data to userspace, encrypt decrypted data. */ 452static int derived_key_encrypt(struct encrypted_key_payload *epayload, 453 const u8 *derived_key, 454 unsigned int derived_keylen) 455{ 456 struct scatterlist sg_in[2]; 457 struct scatterlist sg_out[1]; 458 struct crypto_skcipher *tfm; 459 struct skcipher_request *req; 460 unsigned int encrypted_datalen; 461 u8 iv[AES_BLOCK_SIZE]; 462 int ret; 463 464 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 465 466 req = init_skcipher_req(derived_key, derived_keylen); 467 ret = PTR_ERR(req); 468 if (IS_ERR(req)) 469 goto out; 470 dump_decrypted_data(epayload); 471 472 sg_init_table(sg_in, 2); 473 sg_set_buf(&sg_in[0], epayload->decrypted_data, 474 epayload->decrypted_datalen); 475 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0); 476 477 sg_init_table(sg_out, 1); 478 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); 479 480 memcpy(iv, epayload->iv, sizeof(iv)); 481 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 482 ret = crypto_skcipher_encrypt(req); 483 tfm = crypto_skcipher_reqtfm(req); 484 skcipher_request_free(req); 485 crypto_free_skcipher(tfm); 486 if (ret < 0) 487 pr_err("encrypted_key: failed to encrypt (%d)\n", ret); 488 else 489 dump_encrypted_data(epayload, encrypted_datalen); 490out: 491 return ret; 492} 493 494static int datablob_hmac_append(struct encrypted_key_payload *epayload, 495 const u8 *master_key, size_t master_keylen) 496{ 497 u8 derived_key[HASH_SIZE]; 498 u8 *digest; 499 int ret; 500 501 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 502 if (ret < 0) 503 goto out; 504 505 digest = epayload->format + epayload->datablob_len; 506 ret = calc_hmac(digest, derived_key, sizeof derived_key, 507 epayload->format, epayload->datablob_len); 508 if (!ret) 509 dump_hmac(NULL, digest, HASH_SIZE); 510out: 511 memzero_explicit(derived_key, sizeof(derived_key)); 512 return ret; 513} 514 515/* verify HMAC before decrypting encrypted key */ 516static int datablob_hmac_verify(struct encrypted_key_payload *epayload, 517 const u8 *format, const u8 *master_key, 518 size_t master_keylen) 519{ 520 u8 derived_key[HASH_SIZE]; 521 u8 digest[HASH_SIZE]; 522 int ret; 523 char *p; 524 unsigned short len; 525 526 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 527 if (ret < 0) 528 goto out; 529 530 len = epayload->datablob_len; 531 if (!format) { 532 p = epayload->master_desc; 533 len -= strlen(epayload->format) + 1; 534 } else 535 p = epayload->format; 536 537 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); 538 if (ret < 0) 539 goto out; 540 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len, 541 sizeof(digest)); 542 if (ret) { 543 ret = -EINVAL; 544 dump_hmac("datablob", 545 epayload->format + epayload->datablob_len, 546 HASH_SIZE); 547 dump_hmac("calc", digest, HASH_SIZE); 548 } 549out: 550 memzero_explicit(derived_key, sizeof(derived_key)); 551 return ret; 552} 553 554static int derived_key_decrypt(struct encrypted_key_payload *epayload, 555 const u8 *derived_key, 556 unsigned int derived_keylen) 557{ 558 struct scatterlist sg_in[1]; 559 struct scatterlist sg_out[2]; 560 struct crypto_skcipher *tfm; 561 struct skcipher_request *req; 562 unsigned int encrypted_datalen; 563 u8 iv[AES_BLOCK_SIZE]; 564 u8 *pad; 565 int ret; 566 567 /* Throwaway buffer to hold the unused zero padding at the end */ 568 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL); 569 if (!pad) 570 return -ENOMEM; 571 572 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 573 req = init_skcipher_req(derived_key, derived_keylen); 574 ret = PTR_ERR(req); 575 if (IS_ERR(req)) 576 goto out; 577 dump_encrypted_data(epayload, encrypted_datalen); 578 579 sg_init_table(sg_in, 1); 580 sg_init_table(sg_out, 2); 581 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); 582 sg_set_buf(&sg_out[0], epayload->decrypted_data, 583 epayload->decrypted_datalen); 584 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE); 585 586 memcpy(iv, epayload->iv, sizeof(iv)); 587 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 588 ret = crypto_skcipher_decrypt(req); 589 tfm = crypto_skcipher_reqtfm(req); 590 skcipher_request_free(req); 591 crypto_free_skcipher(tfm); 592 if (ret < 0) 593 goto out; 594 dump_decrypted_data(epayload); 595out: 596 kfree(pad); 597 return ret; 598} 599 600/* Allocate memory for decrypted key and datablob. */ 601static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, 602 const char *format, 603 const char *master_desc, 604 const char *datalen, 605 const char *decrypted_data) 606{ 607 struct encrypted_key_payload *epayload = NULL; 608 unsigned short datablob_len; 609 unsigned short decrypted_datalen; 610 unsigned short payload_datalen; 611 unsigned int encrypted_datalen; 612 unsigned int format_len; 613 long dlen; 614 int i; 615 int ret; 616 617 ret = kstrtol(datalen, 10, &dlen); 618 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) 619 return ERR_PTR(-EINVAL); 620 621 format_len = (!format) ? strlen(key_format_default) : strlen(format); 622 decrypted_datalen = dlen; 623 payload_datalen = decrypted_datalen; 624 625 if (decrypted_data) { 626 if (!user_decrypted_data) { 627 pr_err("encrypted key: instantiation of keys using provided decrypted data is disabled since CONFIG_USER_DECRYPTED_DATA is set to false\n"); 628 return ERR_PTR(-EINVAL); 629 } 630 if (strlen(decrypted_data) != decrypted_datalen * 2) { 631 pr_err("encrypted key: decrypted data provided does not match decrypted data length provided\n"); 632 return ERR_PTR(-EINVAL); 633 } 634 for (i = 0; i < strlen(decrypted_data); i++) { 635 if (!isxdigit(decrypted_data[i])) { 636 pr_err("encrypted key: decrypted data provided must contain only hexadecimal characters\n"); 637 return ERR_PTR(-EINVAL); 638 } 639 } 640 } 641 642 if (format) { 643 if (!strcmp(format, key_format_ecryptfs)) { 644 if (dlen != ECRYPTFS_MAX_KEY_BYTES) { 645 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n", 646 ECRYPTFS_MAX_KEY_BYTES); 647 return ERR_PTR(-EINVAL); 648 } 649 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; 650 payload_datalen = sizeof(struct ecryptfs_auth_tok); 651 } else if (!strcmp(format, key_format_enc32)) { 652 if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) { 653 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n", 654 decrypted_datalen); 655 return ERR_PTR(-EINVAL); 656 } 657 } 658 } 659 660 encrypted_datalen = roundup(decrypted_datalen, blksize); 661 662 datablob_len = format_len + 1 + strlen(master_desc) + 1 663 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; 664 665 ret = key_payload_reserve(key, payload_datalen + datablob_len 666 + HASH_SIZE + 1); 667 if (ret < 0) 668 return ERR_PTR(ret); 669 670 epayload = kzalloc(sizeof(*epayload) + payload_datalen + 671 datablob_len + HASH_SIZE + 1, GFP_KERNEL); 672 if (!epayload) 673 return ERR_PTR(-ENOMEM); 674 675 epayload->payload_datalen = payload_datalen; 676 epayload->decrypted_datalen = decrypted_datalen; 677 epayload->datablob_len = datablob_len; 678 return epayload; 679} 680 681static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, 682 const char *format, const char *hex_encoded_iv) 683{ 684 struct key *mkey; 685 u8 derived_key[HASH_SIZE]; 686 const u8 *master_key; 687 u8 *hmac; 688 const char *hex_encoded_data; 689 unsigned int encrypted_datalen; 690 size_t master_keylen; 691 size_t asciilen; 692 int ret; 693 694 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 695 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; 696 if (strlen(hex_encoded_iv) != asciilen) 697 return -EINVAL; 698 699 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; 700 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); 701 if (ret < 0) 702 return -EINVAL; 703 ret = hex2bin(epayload->encrypted_data, hex_encoded_data, 704 encrypted_datalen); 705 if (ret < 0) 706 return -EINVAL; 707 708 hmac = epayload->format + epayload->datablob_len; 709 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), 710 HASH_SIZE); 711 if (ret < 0) 712 return -EINVAL; 713 714 mkey = request_master_key(epayload, &master_key, &master_keylen); 715 if (IS_ERR(mkey)) 716 return PTR_ERR(mkey); 717 718 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); 719 if (ret < 0) { 720 pr_err("encrypted_key: bad hmac (%d)\n", ret); 721 goto out; 722 } 723 724 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 725 if (ret < 0) 726 goto out; 727 728 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); 729 if (ret < 0) 730 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); 731out: 732 up_read(&mkey->sem); 733 key_put(mkey); 734 memzero_explicit(derived_key, sizeof(derived_key)); 735 return ret; 736} 737 738static void __ekey_init(struct encrypted_key_payload *epayload, 739 const char *format, const char *master_desc, 740 const char *datalen) 741{ 742 unsigned int format_len; 743 744 format_len = (!format) ? strlen(key_format_default) : strlen(format); 745 epayload->format = epayload->payload_data + epayload->payload_datalen; 746 epayload->master_desc = epayload->format + format_len + 1; 747 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; 748 epayload->iv = epayload->datalen + strlen(datalen) + 1; 749 epayload->encrypted_data = epayload->iv + ivsize + 1; 750 epayload->decrypted_data = epayload->payload_data; 751 752 if (!format) 753 memcpy(epayload->format, key_format_default, format_len); 754 else { 755 if (!strcmp(format, key_format_ecryptfs)) 756 epayload->decrypted_data = 757 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); 758 759 memcpy(epayload->format, format, format_len); 760 } 761 762 memcpy(epayload->master_desc, master_desc, strlen(master_desc)); 763 memcpy(epayload->datalen, datalen, strlen(datalen)); 764} 765 766/* 767 * encrypted_init - initialize an encrypted key 768 * 769 * For a new key, use either a random number or user-provided decrypted data in 770 * case it is provided. A random number is used for the iv in both cases. For 771 * an old key, decrypt the hex encoded data. 772 */ 773static int encrypted_init(struct encrypted_key_payload *epayload, 774 const char *key_desc, const char *format, 775 const char *master_desc, const char *datalen, 776 const char *hex_encoded_iv, const char *decrypted_data) 777{ 778 int ret = 0; 779 780 if (format && !strcmp(format, key_format_ecryptfs)) { 781 ret = valid_ecryptfs_desc(key_desc); 782 if (ret < 0) 783 return ret; 784 785 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, 786 key_desc); 787 } 788 789 __ekey_init(epayload, format, master_desc, datalen); 790 if (hex_encoded_iv) { 791 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); 792 } else if (decrypted_data) { 793 get_random_bytes(epayload->iv, ivsize); 794 ret = hex2bin(epayload->decrypted_data, decrypted_data, 795 epayload->decrypted_datalen); 796 } else { 797 get_random_bytes(epayload->iv, ivsize); 798 get_random_bytes(epayload->decrypted_data, epayload->decrypted_datalen); 799 } 800 return ret; 801} 802 803/* 804 * encrypted_instantiate - instantiate an encrypted key 805 * 806 * Instantiates the key: 807 * - by decrypting an existing encrypted datablob, or 808 * - by creating a new encrypted key based on a kernel random number, or 809 * - using provided decrypted data. 810 * 811 * On success, return 0. Otherwise return errno. 812 */ 813static int encrypted_instantiate(struct key *key, 814 struct key_preparsed_payload *prep) 815{ 816 struct encrypted_key_payload *epayload = NULL; 817 char *datablob = NULL; 818 const char *format = NULL; 819 char *master_desc = NULL; 820 char *decrypted_datalen = NULL; 821 char *hex_encoded_iv = NULL; 822 char *decrypted_data = NULL; 823 size_t datalen = prep->datalen; 824 int ret; 825 826 if (datalen <= 0 || datalen > 32767 || !prep->data) 827 return -EINVAL; 828 829 datablob = kmalloc(datalen + 1, GFP_KERNEL); 830 if (!datablob) 831 return -ENOMEM; 832 datablob[datalen] = 0; 833 memcpy(datablob, prep->data, datalen); 834 ret = datablob_parse(datablob, &format, &master_desc, 835 &decrypted_datalen, &hex_encoded_iv, &decrypted_data); 836 if (ret < 0) 837 goto out; 838 839 epayload = encrypted_key_alloc(key, format, master_desc, 840 decrypted_datalen, decrypted_data); 841 if (IS_ERR(epayload)) { 842 ret = PTR_ERR(epayload); 843 goto out; 844 } 845 ret = encrypted_init(epayload, key->description, format, master_desc, 846 decrypted_datalen, hex_encoded_iv, decrypted_data); 847 if (ret < 0) { 848 kfree_sensitive(epayload); 849 goto out; 850 } 851 852 rcu_assign_keypointer(key, epayload); 853out: 854 kfree_sensitive(datablob); 855 return ret; 856} 857 858static void encrypted_rcu_free(struct rcu_head *rcu) 859{ 860 struct encrypted_key_payload *epayload; 861 862 epayload = container_of(rcu, struct encrypted_key_payload, rcu); 863 kfree_sensitive(epayload); 864} 865 866/* 867 * encrypted_update - update the master key description 868 * 869 * Change the master key description for an existing encrypted key. 870 * The next read will return an encrypted datablob using the new 871 * master key description. 872 * 873 * On success, return 0. Otherwise return errno. 874 */ 875static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) 876{ 877 struct encrypted_key_payload *epayload = key->payload.data[0]; 878 struct encrypted_key_payload *new_epayload; 879 char *buf; 880 char *new_master_desc = NULL; 881 const char *format = NULL; 882 size_t datalen = prep->datalen; 883 int ret = 0; 884 885 if (key_is_negative(key)) 886 return -ENOKEY; 887 if (datalen <= 0 || datalen > 32767 || !prep->data) 888 return -EINVAL; 889 890 buf = kmalloc(datalen + 1, GFP_KERNEL); 891 if (!buf) 892 return -ENOMEM; 893 894 buf[datalen] = 0; 895 memcpy(buf, prep->data, datalen); 896 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL, NULL); 897 if (ret < 0) 898 goto out; 899 900 ret = valid_master_desc(new_master_desc, epayload->master_desc); 901 if (ret < 0) 902 goto out; 903 904 new_epayload = encrypted_key_alloc(key, epayload->format, 905 new_master_desc, epayload->datalen, NULL); 906 if (IS_ERR(new_epayload)) { 907 ret = PTR_ERR(new_epayload); 908 goto out; 909 } 910 911 __ekey_init(new_epayload, epayload->format, new_master_desc, 912 epayload->datalen); 913 914 memcpy(new_epayload->iv, epayload->iv, ivsize); 915 memcpy(new_epayload->payload_data, epayload->payload_data, 916 epayload->payload_datalen); 917 918 rcu_assign_keypointer(key, new_epayload); 919 call_rcu(&epayload->rcu, encrypted_rcu_free); 920out: 921 kfree_sensitive(buf); 922 return ret; 923} 924 925/* 926 * encrypted_read - format and copy out the encrypted data 927 * 928 * The resulting datablob format is: 929 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> 930 * 931 * On success, return to userspace the encrypted key datablob size. 932 */ 933static long encrypted_read(const struct key *key, char *buffer, 934 size_t buflen) 935{ 936 struct encrypted_key_payload *epayload; 937 struct key *mkey; 938 const u8 *master_key; 939 size_t master_keylen; 940 char derived_key[HASH_SIZE]; 941 char *ascii_buf; 942 size_t asciiblob_len; 943 int ret; 944 945 epayload = dereference_key_locked(key); 946 947 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ 948 asciiblob_len = epayload->datablob_len + ivsize + 1 949 + roundup(epayload->decrypted_datalen, blksize) 950 + (HASH_SIZE * 2); 951 952 if (!buffer || buflen < asciiblob_len) 953 return asciiblob_len; 954 955 mkey = request_master_key(epayload, &master_key, &master_keylen); 956 if (IS_ERR(mkey)) 957 return PTR_ERR(mkey); 958 959 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 960 if (ret < 0) 961 goto out; 962 963 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); 964 if (ret < 0) 965 goto out; 966 967 ret = datablob_hmac_append(epayload, master_key, master_keylen); 968 if (ret < 0) 969 goto out; 970 971 ascii_buf = datablob_format(epayload, asciiblob_len); 972 if (!ascii_buf) { 973 ret = -ENOMEM; 974 goto out; 975 } 976 977 up_read(&mkey->sem); 978 key_put(mkey); 979 memzero_explicit(derived_key, sizeof(derived_key)); 980 981 memcpy(buffer, ascii_buf, asciiblob_len); 982 kfree_sensitive(ascii_buf); 983 984 return asciiblob_len; 985out: 986 up_read(&mkey->sem); 987 key_put(mkey); 988 memzero_explicit(derived_key, sizeof(derived_key)); 989 return ret; 990} 991 992/* 993 * encrypted_destroy - clear and free the key's payload 994 */ 995static void encrypted_destroy(struct key *key) 996{ 997 kfree_sensitive(key->payload.data[0]); 998} 999 1000struct key_type key_type_encrypted = { 1001 .name = "encrypted", 1002 .instantiate = encrypted_instantiate, 1003 .update = encrypted_update, 1004 .destroy = encrypted_destroy, 1005 .describe = user_describe, 1006 .read = encrypted_read, 1007}; 1008EXPORT_SYMBOL_GPL(key_type_encrypted); 1009 1010static int __init init_encrypted(void) 1011{ 1012 int ret; 1013 1014 hash_tfm = crypto_alloc_shash(hash_alg, 0, 0); 1015 if (IS_ERR(hash_tfm)) { 1016 pr_err("encrypted_key: can't allocate %s transform: %ld\n", 1017 hash_alg, PTR_ERR(hash_tfm)); 1018 return PTR_ERR(hash_tfm); 1019 } 1020 1021 ret = aes_get_sizes(); 1022 if (ret < 0) 1023 goto out; 1024 ret = register_key_type(&key_type_encrypted); 1025 if (ret < 0) 1026 goto out; 1027 return 0; 1028out: 1029 crypto_free_shash(hash_tfm); 1030 return ret; 1031 1032} 1033 1034static void __exit cleanup_encrypted(void) 1035{ 1036 crypto_free_shash(hash_tfm); 1037 unregister_key_type(&key_type_encrypted); 1038} 1039 1040late_initcall(init_encrypted); 1041module_exit(cleanup_encrypted); 1042 1043MODULE_LICENSE("GPL"); 1044