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/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 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 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 */ 104static 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 */ 137static 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 */ 171static 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 } 263out: 264 return ret; 265} 266 267/* 268 * datablob_format - format as an ascii string, before copying to userspace 269 */ 270static 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]); 292out: 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 */ 301static 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; 322error: 323 return ukey; 324} 325 326static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, 327 const u8 *buf, unsigned int buflen) 328{ 329 struct crypto_shash *tfm; 330 int err; 331 332 tfm = crypto_alloc_shash(hmac_alg, 0, 0); 333 if (IS_ERR(tfm)) { 334 pr_err("encrypted_key: can't alloc %s transform: %ld\n", 335 hmac_alg, PTR_ERR(tfm)); 336 return PTR_ERR(tfm); 337 } 338 339 err = crypto_shash_setkey(tfm, key, keylen); 340 if (!err) 341 err = crypto_shash_tfm_digest(tfm, buf, buflen, digest); 342 crypto_free_shash(tfm); 343 return err; 344} 345 346enum derived_key_type { ENC_KEY, AUTH_KEY }; 347 348/* Derive authentication/encryption key from trusted key */ 349static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, 350 const u8 *master_key, size_t master_keylen) 351{ 352 u8 *derived_buf; 353 unsigned int derived_buf_len; 354 int ret; 355 356 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; 357 if (derived_buf_len < HASH_SIZE) 358 derived_buf_len = HASH_SIZE; 359 360 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); 361 if (!derived_buf) 362 return -ENOMEM; 363 364 if (key_type) 365 strcpy(derived_buf, "AUTH_KEY"); 366 else 367 strcpy(derived_buf, "ENC_KEY"); 368 369 memcpy(derived_buf + strlen(derived_buf) + 1, master_key, 370 master_keylen); 371 ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len, 372 derived_key); 373 kfree_sensitive(derived_buf); 374 return ret; 375} 376 377static struct skcipher_request *init_skcipher_req(const u8 *key, 378 unsigned int key_len) 379{ 380 struct skcipher_request *req; 381 struct crypto_skcipher *tfm; 382 int ret; 383 384 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); 385 if (IS_ERR(tfm)) { 386 pr_err("encrypted_key: failed to load %s transform (%ld)\n", 387 blkcipher_alg, PTR_ERR(tfm)); 388 return ERR_CAST(tfm); 389 } 390 391 ret = crypto_skcipher_setkey(tfm, key, key_len); 392 if (ret < 0) { 393 pr_err("encrypted_key: failed to setkey (%d)\n", ret); 394 crypto_free_skcipher(tfm); 395 return ERR_PTR(ret); 396 } 397 398 req = skcipher_request_alloc(tfm, GFP_KERNEL); 399 if (!req) { 400 pr_err("encrypted_key: failed to allocate request for %s\n", 401 blkcipher_alg); 402 crypto_free_skcipher(tfm); 403 return ERR_PTR(-ENOMEM); 404 } 405 406 skcipher_request_set_callback(req, 0, NULL, NULL); 407 return req; 408} 409 410static struct key *request_master_key(struct encrypted_key_payload *epayload, 411 const u8 **master_key, size_t *master_keylen) 412{ 413 struct key *mkey = ERR_PTR(-EINVAL); 414 415 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, 416 KEY_TRUSTED_PREFIX_LEN)) { 417 mkey = request_trusted_key(epayload->master_desc + 418 KEY_TRUSTED_PREFIX_LEN, 419 master_key, master_keylen); 420 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, 421 KEY_USER_PREFIX_LEN)) { 422 mkey = request_user_key(epayload->master_desc + 423 KEY_USER_PREFIX_LEN, 424 master_key, master_keylen); 425 } else 426 goto out; 427 428 if (IS_ERR(mkey)) { 429 int ret = PTR_ERR(mkey); 430 431 if (ret == -ENOTSUPP) 432 pr_info("encrypted_key: key %s not supported", 433 epayload->master_desc); 434 else 435 pr_info("encrypted_key: key %s not found", 436 epayload->master_desc); 437 goto out; 438 } 439 440 dump_master_key(*master_key, *master_keylen); 441out: 442 return mkey; 443} 444 445/* Before returning data to userspace, encrypt decrypted data. */ 446static int derived_key_encrypt(struct encrypted_key_payload *epayload, 447 const u8 *derived_key, 448 unsigned int derived_keylen) 449{ 450 struct scatterlist sg_in[2]; 451 struct scatterlist sg_out[1]; 452 struct crypto_skcipher *tfm; 453 struct skcipher_request *req; 454 unsigned int encrypted_datalen; 455 u8 iv[AES_BLOCK_SIZE]; 456 int ret; 457 458 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 459 460 req = init_skcipher_req(derived_key, derived_keylen); 461 ret = PTR_ERR(req); 462 if (IS_ERR(req)) 463 goto out; 464 dump_decrypted_data(epayload); 465 466 sg_init_table(sg_in, 2); 467 sg_set_buf(&sg_in[0], epayload->decrypted_data, 468 epayload->decrypted_datalen); 469 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0); 470 471 sg_init_table(sg_out, 1); 472 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); 473 474 memcpy(iv, epayload->iv, sizeof(iv)); 475 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 476 ret = crypto_skcipher_encrypt(req); 477 tfm = crypto_skcipher_reqtfm(req); 478 skcipher_request_free(req); 479 crypto_free_skcipher(tfm); 480 if (ret < 0) 481 pr_err("encrypted_key: failed to encrypt (%d)\n", ret); 482 else 483 dump_encrypted_data(epayload, encrypted_datalen); 484out: 485 return ret; 486} 487 488static int datablob_hmac_append(struct encrypted_key_payload *epayload, 489 const u8 *master_key, size_t master_keylen) 490{ 491 u8 derived_key[HASH_SIZE]; 492 u8 *digest; 493 int ret; 494 495 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 496 if (ret < 0) 497 goto out; 498 499 digest = epayload->format + epayload->datablob_len; 500 ret = calc_hmac(digest, derived_key, sizeof derived_key, 501 epayload->format, epayload->datablob_len); 502 if (!ret) 503 dump_hmac(NULL, digest, HASH_SIZE); 504out: 505 memzero_explicit(derived_key, sizeof(derived_key)); 506 return ret; 507} 508 509/* verify HMAC before decrypting encrypted key */ 510static int datablob_hmac_verify(struct encrypted_key_payload *epayload, 511 const u8 *format, const u8 *master_key, 512 size_t master_keylen) 513{ 514 u8 derived_key[HASH_SIZE]; 515 u8 digest[HASH_SIZE]; 516 int ret; 517 char *p; 518 unsigned short len; 519 520 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); 521 if (ret < 0) 522 goto out; 523 524 len = epayload->datablob_len; 525 if (!format) { 526 p = epayload->master_desc; 527 len -= strlen(epayload->format) + 1; 528 } else 529 p = epayload->format; 530 531 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); 532 if (ret < 0) 533 goto out; 534 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len, 535 sizeof(digest)); 536 if (ret) { 537 ret = -EINVAL; 538 dump_hmac("datablob", 539 epayload->format + epayload->datablob_len, 540 HASH_SIZE); 541 dump_hmac("calc", digest, HASH_SIZE); 542 } 543out: 544 memzero_explicit(derived_key, sizeof(derived_key)); 545 return ret; 546} 547 548static int derived_key_decrypt(struct encrypted_key_payload *epayload, 549 const u8 *derived_key, 550 unsigned int derived_keylen) 551{ 552 struct scatterlist sg_in[1]; 553 struct scatterlist sg_out[2]; 554 struct crypto_skcipher *tfm; 555 struct skcipher_request *req; 556 unsigned int encrypted_datalen; 557 u8 iv[AES_BLOCK_SIZE]; 558 u8 *pad; 559 int ret; 560 561 /* Throwaway buffer to hold the unused zero padding at the end */ 562 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL); 563 if (!pad) 564 return -ENOMEM; 565 566 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 567 req = init_skcipher_req(derived_key, derived_keylen); 568 ret = PTR_ERR(req); 569 if (IS_ERR(req)) 570 goto out; 571 dump_encrypted_data(epayload, encrypted_datalen); 572 573 sg_init_table(sg_in, 1); 574 sg_init_table(sg_out, 2); 575 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); 576 sg_set_buf(&sg_out[0], epayload->decrypted_data, 577 epayload->decrypted_datalen); 578 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE); 579 580 memcpy(iv, epayload->iv, sizeof(iv)); 581 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); 582 ret = crypto_skcipher_decrypt(req); 583 tfm = crypto_skcipher_reqtfm(req); 584 skcipher_request_free(req); 585 crypto_free_skcipher(tfm); 586 if (ret < 0) 587 goto out; 588 dump_decrypted_data(epayload); 589out: 590 kfree(pad); 591 return ret; 592} 593 594/* Allocate memory for decrypted key and datablob. */ 595static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, 596 const char *format, 597 const char *master_desc, 598 const char *datalen) 599{ 600 struct encrypted_key_payload *epayload = NULL; 601 unsigned short datablob_len; 602 unsigned short decrypted_datalen; 603 unsigned short payload_datalen; 604 unsigned int encrypted_datalen; 605 unsigned int format_len; 606 long dlen; 607 int ret; 608 609 ret = kstrtol(datalen, 10, &dlen); 610 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) 611 return ERR_PTR(-EINVAL); 612 613 format_len = (!format) ? strlen(key_format_default) : strlen(format); 614 decrypted_datalen = dlen; 615 payload_datalen = decrypted_datalen; 616 if (format) { 617 if (!strcmp(format, key_format_ecryptfs)) { 618 if (dlen != ECRYPTFS_MAX_KEY_BYTES) { 619 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n", 620 ECRYPTFS_MAX_KEY_BYTES); 621 return ERR_PTR(-EINVAL); 622 } 623 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; 624 payload_datalen = sizeof(struct ecryptfs_auth_tok); 625 } else if (!strcmp(format, key_format_enc32)) { 626 if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) { 627 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n", 628 decrypted_datalen); 629 return ERR_PTR(-EINVAL); 630 } 631 } 632 } 633 634 encrypted_datalen = roundup(decrypted_datalen, blksize); 635 636 datablob_len = format_len + 1 + strlen(master_desc) + 1 637 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; 638 639 ret = key_payload_reserve(key, payload_datalen + datablob_len 640 + HASH_SIZE + 1); 641 if (ret < 0) 642 return ERR_PTR(ret); 643 644 epayload = kzalloc(sizeof(*epayload) + payload_datalen + 645 datablob_len + HASH_SIZE + 1, GFP_KERNEL); 646 if (!epayload) 647 return ERR_PTR(-ENOMEM); 648 649 epayload->payload_datalen = payload_datalen; 650 epayload->decrypted_datalen = decrypted_datalen; 651 epayload->datablob_len = datablob_len; 652 return epayload; 653} 654 655static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, 656 const char *format, const char *hex_encoded_iv) 657{ 658 struct key *mkey; 659 u8 derived_key[HASH_SIZE]; 660 const u8 *master_key; 661 u8 *hmac; 662 const char *hex_encoded_data; 663 unsigned int encrypted_datalen; 664 size_t master_keylen; 665 size_t asciilen; 666 int ret; 667 668 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); 669 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; 670 if (strlen(hex_encoded_iv) != asciilen) 671 return -EINVAL; 672 673 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; 674 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); 675 if (ret < 0) 676 return -EINVAL; 677 ret = hex2bin(epayload->encrypted_data, hex_encoded_data, 678 encrypted_datalen); 679 if (ret < 0) 680 return -EINVAL; 681 682 hmac = epayload->format + epayload->datablob_len; 683 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), 684 HASH_SIZE); 685 if (ret < 0) 686 return -EINVAL; 687 688 mkey = request_master_key(epayload, &master_key, &master_keylen); 689 if (IS_ERR(mkey)) 690 return PTR_ERR(mkey); 691 692 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); 693 if (ret < 0) { 694 pr_err("encrypted_key: bad hmac (%d)\n", ret); 695 goto out; 696 } 697 698 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 699 if (ret < 0) 700 goto out; 701 702 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); 703 if (ret < 0) 704 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); 705out: 706 up_read(&mkey->sem); 707 key_put(mkey); 708 memzero_explicit(derived_key, sizeof(derived_key)); 709 return ret; 710} 711 712static void __ekey_init(struct encrypted_key_payload *epayload, 713 const char *format, const char *master_desc, 714 const char *datalen) 715{ 716 unsigned int format_len; 717 718 format_len = (!format) ? strlen(key_format_default) : strlen(format); 719 epayload->format = epayload->payload_data + epayload->payload_datalen; 720 epayload->master_desc = epayload->format + format_len + 1; 721 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; 722 epayload->iv = epayload->datalen + strlen(datalen) + 1; 723 epayload->encrypted_data = epayload->iv + ivsize + 1; 724 epayload->decrypted_data = epayload->payload_data; 725 726 if (!format) 727 memcpy(epayload->format, key_format_default, format_len); 728 else { 729 if (!strcmp(format, key_format_ecryptfs)) 730 epayload->decrypted_data = 731 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); 732 733 memcpy(epayload->format, format, format_len); 734 } 735 736 memcpy(epayload->master_desc, master_desc, strlen(master_desc)); 737 memcpy(epayload->datalen, datalen, strlen(datalen)); 738} 739 740/* 741 * encrypted_init - initialize an encrypted key 742 * 743 * For a new key, use a random number for both the iv and data 744 * itself. For an old key, decrypt the hex encoded data. 745 */ 746static int encrypted_init(struct encrypted_key_payload *epayload, 747 const char *key_desc, const char *format, 748 const char *master_desc, const char *datalen, 749 const char *hex_encoded_iv) 750{ 751 int ret = 0; 752 753 if (format && !strcmp(format, key_format_ecryptfs)) { 754 ret = valid_ecryptfs_desc(key_desc); 755 if (ret < 0) 756 return ret; 757 758 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, 759 key_desc); 760 } 761 762 __ekey_init(epayload, format, master_desc, datalen); 763 if (!hex_encoded_iv) { 764 get_random_bytes(epayload->iv, ivsize); 765 766 get_random_bytes(epayload->decrypted_data, 767 epayload->decrypted_datalen); 768 } else 769 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); 770 return ret; 771} 772 773/* 774 * encrypted_instantiate - instantiate an encrypted key 775 * 776 * Decrypt an existing encrypted datablob or create a new encrypted key 777 * based on a kernel random number. 778 * 779 * On success, return 0. Otherwise return errno. 780 */ 781static int encrypted_instantiate(struct key *key, 782 struct key_preparsed_payload *prep) 783{ 784 struct encrypted_key_payload *epayload = NULL; 785 char *datablob = NULL; 786 const char *format = NULL; 787 char *master_desc = NULL; 788 char *decrypted_datalen = NULL; 789 char *hex_encoded_iv = NULL; 790 size_t datalen = prep->datalen; 791 int ret; 792 793 if (datalen <= 0 || datalen > 32767 || !prep->data) 794 return -EINVAL; 795 796 datablob = kmalloc(datalen + 1, GFP_KERNEL); 797 if (!datablob) 798 return -ENOMEM; 799 datablob[datalen] = 0; 800 memcpy(datablob, prep->data, datalen); 801 ret = datablob_parse(datablob, &format, &master_desc, 802 &decrypted_datalen, &hex_encoded_iv); 803 if (ret < 0) 804 goto out; 805 806 epayload = encrypted_key_alloc(key, format, master_desc, 807 decrypted_datalen); 808 if (IS_ERR(epayload)) { 809 ret = PTR_ERR(epayload); 810 goto out; 811 } 812 ret = encrypted_init(epayload, key->description, format, master_desc, 813 decrypted_datalen, hex_encoded_iv); 814 if (ret < 0) { 815 kfree_sensitive(epayload); 816 goto out; 817 } 818 819 rcu_assign_keypointer(key, epayload); 820out: 821 kfree_sensitive(datablob); 822 return ret; 823} 824 825static void encrypted_rcu_free(struct rcu_head *rcu) 826{ 827 struct encrypted_key_payload *epayload; 828 829 epayload = container_of(rcu, struct encrypted_key_payload, rcu); 830 kfree_sensitive(epayload); 831} 832 833/* 834 * encrypted_update - update the master key description 835 * 836 * Change the master key description for an existing encrypted key. 837 * The next read will return an encrypted datablob using the new 838 * master key description. 839 * 840 * On success, return 0. Otherwise return errno. 841 */ 842static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) 843{ 844 struct encrypted_key_payload *epayload = key->payload.data[0]; 845 struct encrypted_key_payload *new_epayload; 846 char *buf; 847 char *new_master_desc = NULL; 848 const char *format = NULL; 849 size_t datalen = prep->datalen; 850 int ret = 0; 851 852 if (key_is_negative(key)) 853 return -ENOKEY; 854 if (datalen <= 0 || datalen > 32767 || !prep->data) 855 return -EINVAL; 856 857 buf = kmalloc(datalen + 1, GFP_KERNEL); 858 if (!buf) 859 return -ENOMEM; 860 861 buf[datalen] = 0; 862 memcpy(buf, prep->data, datalen); 863 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); 864 if (ret < 0) 865 goto out; 866 867 ret = valid_master_desc(new_master_desc, epayload->master_desc); 868 if (ret < 0) 869 goto out; 870 871 new_epayload = encrypted_key_alloc(key, epayload->format, 872 new_master_desc, epayload->datalen); 873 if (IS_ERR(new_epayload)) { 874 ret = PTR_ERR(new_epayload); 875 goto out; 876 } 877 878 __ekey_init(new_epayload, epayload->format, new_master_desc, 879 epayload->datalen); 880 881 memcpy(new_epayload->iv, epayload->iv, ivsize); 882 memcpy(new_epayload->payload_data, epayload->payload_data, 883 epayload->payload_datalen); 884 885 rcu_assign_keypointer(key, new_epayload); 886 call_rcu(&epayload->rcu, encrypted_rcu_free); 887out: 888 kfree_sensitive(buf); 889 return ret; 890} 891 892/* 893 * encrypted_read - format and copy out the encrypted data 894 * 895 * The resulting datablob format is: 896 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> 897 * 898 * On success, return to userspace the encrypted key datablob size. 899 */ 900static long encrypted_read(const struct key *key, char *buffer, 901 size_t buflen) 902{ 903 struct encrypted_key_payload *epayload; 904 struct key *mkey; 905 const u8 *master_key; 906 size_t master_keylen; 907 char derived_key[HASH_SIZE]; 908 char *ascii_buf; 909 size_t asciiblob_len; 910 int ret; 911 912 epayload = dereference_key_locked(key); 913 914 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ 915 asciiblob_len = epayload->datablob_len + ivsize + 1 916 + roundup(epayload->decrypted_datalen, blksize) 917 + (HASH_SIZE * 2); 918 919 if (!buffer || buflen < asciiblob_len) 920 return asciiblob_len; 921 922 mkey = request_master_key(epayload, &master_key, &master_keylen); 923 if (IS_ERR(mkey)) 924 return PTR_ERR(mkey); 925 926 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); 927 if (ret < 0) 928 goto out; 929 930 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); 931 if (ret < 0) 932 goto out; 933 934 ret = datablob_hmac_append(epayload, master_key, master_keylen); 935 if (ret < 0) 936 goto out; 937 938 ascii_buf = datablob_format(epayload, asciiblob_len); 939 if (!ascii_buf) { 940 ret = -ENOMEM; 941 goto out; 942 } 943 944 up_read(&mkey->sem); 945 key_put(mkey); 946 memzero_explicit(derived_key, sizeof(derived_key)); 947 948 memcpy(buffer, ascii_buf, asciiblob_len); 949 kfree_sensitive(ascii_buf); 950 951 return asciiblob_len; 952out: 953 up_read(&mkey->sem); 954 key_put(mkey); 955 memzero_explicit(derived_key, sizeof(derived_key)); 956 return ret; 957} 958 959/* 960 * encrypted_destroy - clear and free the key's payload 961 */ 962static void encrypted_destroy(struct key *key) 963{ 964 kfree_sensitive(key->payload.data[0]); 965} 966 967struct key_type key_type_encrypted = { 968 .name = "encrypted", 969 .instantiate = encrypted_instantiate, 970 .update = encrypted_update, 971 .destroy = encrypted_destroy, 972 .describe = user_describe, 973 .read = encrypted_read, 974}; 975EXPORT_SYMBOL_GPL(key_type_encrypted); 976 977static int __init init_encrypted(void) 978{ 979 int ret; 980 981 hash_tfm = crypto_alloc_shash(hash_alg, 0, 0); 982 if (IS_ERR(hash_tfm)) { 983 pr_err("encrypted_key: can't allocate %s transform: %ld\n", 984 hash_alg, PTR_ERR(hash_tfm)); 985 return PTR_ERR(hash_tfm); 986 } 987 988 ret = aes_get_sizes(); 989 if (ret < 0) 990 goto out; 991 ret = register_key_type(&key_type_encrypted); 992 if (ret < 0) 993 goto out; 994 return 0; 995out: 996 crypto_free_shash(hash_tfm); 997 return ret; 998 999} 1000 1001static void __exit cleanup_encrypted(void) 1002{ 1003 crypto_free_shash(hash_tfm); 1004 unregister_key_type(&key_type_encrypted); 1005} 1006 1007late_initcall(init_encrypted); 1008module_exit(cleanup_encrypted); 1009 1010MODULE_LICENSE("GPL"); 1011