1 /* 2 * Copyright (c) 2013, Google Inc. 3 * 4 * SPDX-License-Identifier: GPL-2.0+ 5 */ 6 7 #include "mkimage.h" 8 #include <stdio.h> 9 #include <string.h> 10 #include <image.h> 11 #include <time.h> 12 #include <openssl/bn.h> 13 #include <openssl/rsa.h> 14 #include <openssl/pem.h> 15 #include <openssl/err.h> 16 #include <openssl/ssl.h> 17 #include <openssl/evp.h> 18 #include <openssl/engine.h> 19 20 #if OPENSSL_VERSION_NUMBER >= 0x10000000L 21 #define HAVE_ERR_REMOVE_THREAD_STATE 22 #endif 23 24 #if OPENSSL_VERSION_NUMBER < 0x10100000L 25 static void RSA_get0_key(const RSA *r, 26 const BIGNUM **n, const BIGNUM **e, const BIGNUM **d) 27 { 28 if (n != NULL) 29 *n = r->n; 30 if (e != NULL) 31 *e = r->e; 32 if (d != NULL) 33 *d = r->d; 34 } 35 #endif 36 37 static int rsa_err(const char *msg) 38 { 39 unsigned long sslErr = ERR_get_error(); 40 41 fprintf(stderr, "%s", msg); 42 fprintf(stderr, ": %s\n", 43 ERR_error_string(sslErr, 0)); 44 45 return -1; 46 } 47 48 /** 49 * rsa_pem_get_pub_key() - read a public key from a .crt file 50 * 51 * @keydir: Directory containins the key 52 * @name Name of key file (will have a .crt extension) 53 * @rsap Returns RSA object, or NULL on failure 54 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 55 */ 56 static int rsa_pem_get_pub_key(const char *keydir, const char *name, RSA **rsap) 57 { 58 char path[1024]; 59 EVP_PKEY *key; 60 X509 *cert; 61 RSA *rsa; 62 FILE *f; 63 int ret; 64 65 *rsap = NULL; 66 snprintf(path, sizeof(path), "%s/%s.crt", keydir, name); 67 f = fopen(path, "r"); 68 if (!f) { 69 fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n", 70 path, strerror(errno)); 71 return -EACCES; 72 } 73 74 /* Read the certificate */ 75 cert = NULL; 76 if (!PEM_read_X509(f, &cert, NULL, NULL)) { 77 rsa_err("Couldn't read certificate"); 78 ret = -EINVAL; 79 goto err_cert; 80 } 81 82 /* Get the public key from the certificate. */ 83 key = X509_get_pubkey(cert); 84 if (!key) { 85 rsa_err("Couldn't read public key\n"); 86 ret = -EINVAL; 87 goto err_pubkey; 88 } 89 90 /* Convert to a RSA_style key. */ 91 rsa = EVP_PKEY_get1_RSA(key); 92 if (!rsa) { 93 rsa_err("Couldn't convert to a RSA style key"); 94 ret = -EINVAL; 95 goto err_rsa; 96 } 97 fclose(f); 98 EVP_PKEY_free(key); 99 X509_free(cert); 100 *rsap = rsa; 101 102 return 0; 103 104 err_rsa: 105 EVP_PKEY_free(key); 106 err_pubkey: 107 X509_free(cert); 108 err_cert: 109 fclose(f); 110 return ret; 111 } 112 113 /** 114 * rsa_engine_get_pub_key() - read a public key from given engine 115 * 116 * @keydir: Key prefix 117 * @name Name of key 118 * @engine Engine to use 119 * @rsap Returns RSA object, or NULL on failure 120 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 121 */ 122 static int rsa_engine_get_pub_key(const char *keydir, const char *name, 123 ENGINE *engine, RSA **rsap) 124 { 125 const char *engine_id; 126 char key_id[1024]; 127 EVP_PKEY *key; 128 RSA *rsa; 129 int ret; 130 131 *rsap = NULL; 132 133 engine_id = ENGINE_get_id(engine); 134 135 if (engine_id && !strcmp(engine_id, "pkcs11")) { 136 if (keydir) 137 snprintf(key_id, sizeof(key_id), 138 "pkcs11:%s;object=%s;type=public", 139 keydir, name); 140 else 141 snprintf(key_id, sizeof(key_id), 142 "pkcs11:object=%s;type=public", 143 name); 144 } else { 145 fprintf(stderr, "Engine not supported\n"); 146 return -ENOTSUP; 147 } 148 149 key = ENGINE_load_public_key(engine, key_id, NULL, NULL); 150 if (!key) 151 return rsa_err("Failure loading public key from engine"); 152 153 /* Convert to a RSA_style key. */ 154 rsa = EVP_PKEY_get1_RSA(key); 155 if (!rsa) { 156 rsa_err("Couldn't convert to a RSA style key"); 157 ret = -EINVAL; 158 goto err_rsa; 159 } 160 161 EVP_PKEY_free(key); 162 *rsap = rsa; 163 164 return 0; 165 166 err_rsa: 167 EVP_PKEY_free(key); 168 return ret; 169 } 170 171 /** 172 * rsa_get_pub_key() - read a public key 173 * 174 * @keydir: Directory containing the key (PEM file) or key prefix (engine) 175 * @name Name of key file (will have a .crt extension) 176 * @engine Engine to use 177 * @rsap Returns RSA object, or NULL on failure 178 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 179 */ 180 static int rsa_get_pub_key(const char *keydir, const char *name, 181 ENGINE *engine, RSA **rsap) 182 { 183 if (engine) 184 return rsa_engine_get_pub_key(keydir, name, engine, rsap); 185 return rsa_pem_get_pub_key(keydir, name, rsap); 186 } 187 188 /** 189 * rsa_pem_get_priv_key() - read a private key from a .key file 190 * 191 * @keydir: Directory containing the key 192 * @name Name of key file (will have a .key extension) 193 * @rsap Returns RSA object, or NULL on failure 194 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 195 */ 196 static int rsa_pem_get_priv_key(const char *keydir, const char *name, 197 RSA **rsap) 198 { 199 char path[1024]; 200 RSA *rsa; 201 FILE *f; 202 203 *rsap = NULL; 204 snprintf(path, sizeof(path), "%s/%s.key", keydir, name); 205 f = fopen(path, "r"); 206 if (!f) { 207 fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n", 208 path, strerror(errno)); 209 return -ENOENT; 210 } 211 212 rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path); 213 if (!rsa) { 214 rsa_err("Failure reading private key"); 215 fclose(f); 216 return -EPROTO; 217 } 218 fclose(f); 219 *rsap = rsa; 220 221 return 0; 222 } 223 224 /** 225 * rsa_engine_get_priv_key() - read a private key from given engine 226 * 227 * @keydir: Key prefix 228 * @name Name of key 229 * @engine Engine to use 230 * @rsap Returns RSA object, or NULL on failure 231 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 232 */ 233 static int rsa_engine_get_priv_key(const char *keydir, const char *name, 234 ENGINE *engine, RSA **rsap) 235 { 236 const char *engine_id; 237 char key_id[1024]; 238 EVP_PKEY *key; 239 RSA *rsa; 240 int ret; 241 242 *rsap = NULL; 243 244 engine_id = ENGINE_get_id(engine); 245 246 if (engine_id && !strcmp(engine_id, "pkcs11")) { 247 if (keydir) 248 snprintf(key_id, sizeof(key_id), 249 "pkcs11:%s;object=%s;type=private", 250 keydir, name); 251 else 252 snprintf(key_id, sizeof(key_id), 253 "pkcs11:object=%s;type=private", 254 name); 255 } else { 256 fprintf(stderr, "Engine not supported\n"); 257 return -ENOTSUP; 258 } 259 260 key = ENGINE_load_private_key(engine, key_id, NULL, NULL); 261 if (!key) 262 return rsa_err("Failure loading private key from engine"); 263 264 /* Convert to a RSA_style key. */ 265 rsa = EVP_PKEY_get1_RSA(key); 266 if (!rsa) { 267 rsa_err("Couldn't convert to a RSA style key"); 268 ret = -EINVAL; 269 goto err_rsa; 270 } 271 272 EVP_PKEY_free(key); 273 *rsap = rsa; 274 275 return 0; 276 277 err_rsa: 278 EVP_PKEY_free(key); 279 return ret; 280 } 281 282 /** 283 * rsa_get_priv_key() - read a private key 284 * 285 * @keydir: Directory containing the key (PEM file) or key prefix (engine) 286 * @name Name of key 287 * @engine Engine to use for signing 288 * @rsap Returns RSA object, or NULL on failure 289 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 290 */ 291 static int rsa_get_priv_key(const char *keydir, const char *name, 292 ENGINE *engine, RSA **rsap) 293 { 294 if (engine) 295 return rsa_engine_get_priv_key(keydir, name, engine, rsap); 296 return rsa_pem_get_priv_key(keydir, name, rsap); 297 } 298 299 static int rsa_init(void) 300 { 301 int ret; 302 303 #if OPENSSL_VERSION_NUMBER < 0x10100000L 304 ret = SSL_library_init(); 305 #else 306 ret = OPENSSL_init_ssl(0, NULL); 307 #endif 308 if (!ret) { 309 fprintf(stderr, "Failure to init SSL library\n"); 310 return -1; 311 } 312 #if OPENSSL_VERSION_NUMBER < 0x10100000L 313 SSL_load_error_strings(); 314 315 OpenSSL_add_all_algorithms(); 316 OpenSSL_add_all_digests(); 317 OpenSSL_add_all_ciphers(); 318 #endif 319 320 return 0; 321 } 322 323 static int rsa_engine_init(const char *engine_id, ENGINE **pe) 324 { 325 ENGINE *e; 326 int ret; 327 328 ENGINE_load_builtin_engines(); 329 330 e = ENGINE_by_id(engine_id); 331 if (!e) { 332 fprintf(stderr, "Engine isn't available\n"); 333 ret = -1; 334 goto err_engine_by_id; 335 } 336 337 if (!ENGINE_init(e)) { 338 fprintf(stderr, "Couldn't initialize engine\n"); 339 ret = -1; 340 goto err_engine_init; 341 } 342 343 if (!ENGINE_set_default_RSA(e)) { 344 fprintf(stderr, "Couldn't set engine as default for RSA\n"); 345 ret = -1; 346 goto err_set_rsa; 347 } 348 349 *pe = e; 350 351 return 0; 352 353 err_set_rsa: 354 ENGINE_finish(e); 355 err_engine_init: 356 ENGINE_free(e); 357 err_engine_by_id: 358 #if OPENSSL_VERSION_NUMBER < 0x10100000L 359 ENGINE_cleanup(); 360 #endif 361 return ret; 362 } 363 364 static void rsa_remove(void) 365 { 366 #if OPENSSL_VERSION_NUMBER < 0x10100000L 367 CRYPTO_cleanup_all_ex_data(); 368 ERR_free_strings(); 369 #ifdef HAVE_ERR_REMOVE_THREAD_STATE 370 ERR_remove_thread_state(NULL); 371 #else 372 ERR_remove_state(0); 373 #endif 374 EVP_cleanup(); 375 #endif 376 } 377 378 static void rsa_engine_remove(ENGINE *e) 379 { 380 if (e) { 381 ENGINE_finish(e); 382 ENGINE_free(e); 383 } 384 } 385 386 static int rsa_sign_with_key(RSA *rsa, struct checksum_algo *checksum_algo, 387 const struct image_region region[], int region_count, 388 uint8_t **sigp, uint *sig_size) 389 { 390 EVP_PKEY *key; 391 EVP_MD_CTX *context; 392 int size, ret = 0; 393 uint8_t *sig; 394 int i; 395 396 key = EVP_PKEY_new(); 397 if (!key) 398 return rsa_err("EVP_PKEY object creation failed"); 399 400 if (!EVP_PKEY_set1_RSA(key, rsa)) { 401 ret = rsa_err("EVP key setup failed"); 402 goto err_set; 403 } 404 405 size = EVP_PKEY_size(key); 406 sig = malloc(size); 407 if (!sig) { 408 fprintf(stderr, "Out of memory for signature (%d bytes)\n", 409 size); 410 ret = -ENOMEM; 411 goto err_alloc; 412 } 413 414 context = EVP_MD_CTX_create(); 415 if (!context) { 416 ret = rsa_err("EVP context creation failed"); 417 goto err_create; 418 } 419 EVP_MD_CTX_init(context); 420 if (!EVP_SignInit(context, checksum_algo->calculate_sign())) { 421 ret = rsa_err("Signer setup failed"); 422 goto err_sign; 423 } 424 425 for (i = 0; i < region_count; i++) { 426 if (!EVP_SignUpdate(context, region[i].data, region[i].size)) { 427 ret = rsa_err("Signing data failed"); 428 goto err_sign; 429 } 430 } 431 432 if (!EVP_SignFinal(context, sig, sig_size, key)) { 433 ret = rsa_err("Could not obtain signature"); 434 goto err_sign; 435 } 436 #if OPENSSL_VERSION_NUMBER < 0x10100000L 437 EVP_MD_CTX_cleanup(context); 438 #else 439 EVP_MD_CTX_reset(context); 440 #endif 441 EVP_MD_CTX_destroy(context); 442 EVP_PKEY_free(key); 443 444 debug("Got signature: %d bytes, expected %d\n", *sig_size, size); 445 *sigp = sig; 446 *sig_size = size; 447 448 return 0; 449 450 err_sign: 451 EVP_MD_CTX_destroy(context); 452 err_create: 453 free(sig); 454 err_alloc: 455 err_set: 456 EVP_PKEY_free(key); 457 return ret; 458 } 459 460 int rsa_sign(struct image_sign_info *info, 461 const struct image_region region[], int region_count, 462 uint8_t **sigp, uint *sig_len) 463 { 464 RSA *rsa; 465 ENGINE *e = NULL; 466 int ret; 467 468 ret = rsa_init(); 469 if (ret) 470 return ret; 471 472 if (info->engine_id) { 473 ret = rsa_engine_init(info->engine_id, &e); 474 if (ret) 475 goto err_engine; 476 } 477 478 ret = rsa_get_priv_key(info->keydir, info->keyname, e, &rsa); 479 if (ret) 480 goto err_priv; 481 ret = rsa_sign_with_key(rsa, info->checksum, region, 482 region_count, sigp, sig_len); 483 if (ret) 484 goto err_sign; 485 486 RSA_free(rsa); 487 if (info->engine_id) 488 rsa_engine_remove(e); 489 rsa_remove(); 490 491 return ret; 492 493 err_sign: 494 RSA_free(rsa); 495 err_priv: 496 if (info->engine_id) 497 rsa_engine_remove(e); 498 err_engine: 499 rsa_remove(); 500 return ret; 501 } 502 503 /* 504 * rsa_get_exponent(): - Get the public exponent from an RSA key 505 */ 506 static int rsa_get_exponent(RSA *key, uint64_t *e) 507 { 508 int ret; 509 BIGNUM *bn_te; 510 const BIGNUM *key_e; 511 uint64_t te; 512 513 ret = -EINVAL; 514 bn_te = NULL; 515 516 if (!e) 517 goto cleanup; 518 519 RSA_get0_key(key, NULL, &key_e, NULL); 520 if (BN_num_bits(key_e) > 64) 521 goto cleanup; 522 523 *e = BN_get_word(key_e); 524 525 if (BN_num_bits(key_e) < 33) { 526 ret = 0; 527 goto cleanup; 528 } 529 530 bn_te = BN_dup(key_e); 531 if (!bn_te) 532 goto cleanup; 533 534 if (!BN_rshift(bn_te, bn_te, 32)) 535 goto cleanup; 536 537 if (!BN_mask_bits(bn_te, 32)) 538 goto cleanup; 539 540 te = BN_get_word(bn_te); 541 te <<= 32; 542 *e |= te; 543 ret = 0; 544 545 cleanup: 546 if (bn_te) 547 BN_free(bn_te); 548 549 return ret; 550 } 551 552 /* 553 * rsa_get_params(): - Get the important parameters of an RSA public key 554 */ 555 int rsa_get_params(RSA *key, uint64_t *exponent, uint32_t *n0_invp, 556 BIGNUM **modulusp, BIGNUM **r_squaredp) 557 { 558 BIGNUM *big1, *big2, *big32, *big2_32; 559 BIGNUM *n, *r, *r_squared, *tmp; 560 const BIGNUM *key_n; 561 BN_CTX *bn_ctx = BN_CTX_new(); 562 int ret = 0; 563 564 /* Initialize BIGNUMs */ 565 big1 = BN_new(); 566 big2 = BN_new(); 567 big32 = BN_new(); 568 r = BN_new(); 569 r_squared = BN_new(); 570 tmp = BN_new(); 571 big2_32 = BN_new(); 572 n = BN_new(); 573 if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 || 574 !n) { 575 fprintf(stderr, "Out of memory (bignum)\n"); 576 return -ENOMEM; 577 } 578 579 if (0 != rsa_get_exponent(key, exponent)) 580 ret = -1; 581 582 RSA_get0_key(key, &key_n, NULL, NULL); 583 if (!BN_copy(n, key_n) || !BN_set_word(big1, 1L) || 584 !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L)) 585 ret = -1; 586 587 /* big2_32 = 2^32 */ 588 if (!BN_exp(big2_32, big2, big32, bn_ctx)) 589 ret = -1; 590 591 /* Calculate n0_inv = -1 / n[0] mod 2^32 */ 592 if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) || 593 !BN_sub(tmp, big2_32, tmp)) 594 ret = -1; 595 *n0_invp = BN_get_word(tmp); 596 597 /* Calculate R = 2^(# of key bits) */ 598 if (!BN_set_word(tmp, BN_num_bits(n)) || 599 !BN_exp(r, big2, tmp, bn_ctx)) 600 ret = -1; 601 602 /* Calculate r_squared = R^2 mod n */ 603 if (!BN_copy(r_squared, r) || 604 !BN_mul(tmp, r_squared, r, bn_ctx) || 605 !BN_mod(r_squared, tmp, n, bn_ctx)) 606 ret = -1; 607 608 *modulusp = n; 609 *r_squaredp = r_squared; 610 611 BN_free(big1); 612 BN_free(big2); 613 BN_free(big32); 614 BN_free(r); 615 BN_free(tmp); 616 BN_free(big2_32); 617 if (ret) { 618 fprintf(stderr, "Bignum operations failed\n"); 619 return -ENOMEM; 620 } 621 622 return ret; 623 } 624 625 static int fdt_add_bignum(void *blob, int noffset, const char *prop_name, 626 BIGNUM *num, int num_bits) 627 { 628 int nwords = num_bits / 32; 629 int size; 630 uint32_t *buf, *ptr; 631 BIGNUM *tmp, *big2, *big32, *big2_32; 632 BN_CTX *ctx; 633 int ret; 634 635 tmp = BN_new(); 636 big2 = BN_new(); 637 big32 = BN_new(); 638 big2_32 = BN_new(); 639 if (!tmp || !big2 || !big32 || !big2_32) { 640 fprintf(stderr, "Out of memory (bignum)\n"); 641 return -ENOMEM; 642 } 643 ctx = BN_CTX_new(); 644 if (!tmp) { 645 fprintf(stderr, "Out of memory (bignum context)\n"); 646 return -ENOMEM; 647 } 648 BN_set_word(big2, 2L); 649 BN_set_word(big32, 32L); 650 BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */ 651 652 size = nwords * sizeof(uint32_t); 653 buf = malloc(size); 654 if (!buf) { 655 fprintf(stderr, "Out of memory (%d bytes)\n", size); 656 return -ENOMEM; 657 } 658 659 /* Write out modulus as big endian array of integers */ 660 for (ptr = buf + nwords - 1; ptr >= buf; ptr--) { 661 BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */ 662 *ptr = cpu_to_fdt32(BN_get_word(tmp)); 663 BN_rshift(num, num, 32); /* N = N/B */ 664 } 665 666 /* 667 * We try signing with successively increasing size values, so this 668 * might fail several times 669 */ 670 ret = fdt_setprop(blob, noffset, prop_name, buf, size); 671 if (ret) 672 return -FDT_ERR_NOSPACE; 673 free(buf); 674 BN_free(tmp); 675 BN_free(big2); 676 BN_free(big32); 677 BN_free(big2_32); 678 679 return ret; 680 } 681 682 int rsa_add_verify_data(struct image_sign_info *info, void *keydest) 683 { 684 BIGNUM *modulus, *r_squared; 685 uint64_t exponent; 686 uint32_t n0_inv; 687 int parent, node; 688 char name[100]; 689 int ret; 690 int bits; 691 RSA *rsa; 692 ENGINE *e = NULL; 693 694 debug("%s: Getting verification data\n", __func__); 695 if (info->engine_id) { 696 ret = rsa_engine_init(info->engine_id, &e); 697 if (ret) 698 return ret; 699 } 700 ret = rsa_get_pub_key(info->keydir, info->keyname, e, &rsa); 701 if (ret) 702 goto err_get_pub_key; 703 ret = rsa_get_params(rsa, &exponent, &n0_inv, &modulus, &r_squared); 704 if (ret) 705 goto err_get_params; 706 bits = BN_num_bits(modulus); 707 parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME); 708 if (parent == -FDT_ERR_NOTFOUND) { 709 parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME); 710 if (parent < 0) { 711 ret = parent; 712 if (ret != -FDT_ERR_NOSPACE) { 713 fprintf(stderr, "Couldn't create signature node: %s\n", 714 fdt_strerror(parent)); 715 } 716 } 717 } 718 if (ret) 719 goto done; 720 721 /* Either create or overwrite the named key node */ 722 snprintf(name, sizeof(name), "key-%s", info->keyname); 723 node = fdt_subnode_offset(keydest, parent, name); 724 if (node == -FDT_ERR_NOTFOUND) { 725 node = fdt_add_subnode(keydest, parent, name); 726 if (node < 0) { 727 ret = node; 728 if (ret != -FDT_ERR_NOSPACE) { 729 fprintf(stderr, "Could not create key subnode: %s\n", 730 fdt_strerror(node)); 731 } 732 } 733 } else if (node < 0) { 734 fprintf(stderr, "Cannot select keys parent: %s\n", 735 fdt_strerror(node)); 736 ret = node; 737 } 738 739 if (!ret) { 740 ret = fdt_setprop_string(keydest, node, "key-name-hint", 741 info->keyname); 742 } 743 if (!ret) 744 ret = fdt_setprop_u32(keydest, node, "rsa,num-bits", bits); 745 if (!ret) 746 ret = fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv); 747 if (!ret) { 748 ret = fdt_setprop_u64(keydest, node, "rsa,exponent", exponent); 749 } 750 if (!ret) { 751 ret = fdt_add_bignum(keydest, node, "rsa,modulus", modulus, 752 bits); 753 } 754 if (!ret) { 755 ret = fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared, 756 bits); 757 } 758 if (!ret) { 759 ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP, 760 info->name); 761 } 762 if (!ret && info->require_keys) { 763 ret = fdt_setprop_string(keydest, node, "required", 764 info->require_keys); 765 } 766 done: 767 BN_free(modulus); 768 BN_free(r_squared); 769 if (ret) 770 ret = ret == -FDT_ERR_NOSPACE ? -ENOSPC : -EIO; 771 err_get_params: 772 RSA_free(rsa); 773 err_get_pub_key: 774 if (info->engine_id) 775 rsa_engine_remove(e); 776 777 return ret; 778 } 779