1 /*- 2 * Copyright (c) 2017-2018, Juniper Networks, Inc. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 14 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 15 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 16 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 17 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 18 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 19 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 #include <sys/cdefs.h> 26 __FBSDID("$FreeBSD$"); 27 28 /** 29 * @file vets.c - trust store 30 * @brief verify signatures 31 * 32 * We leverage code from BearSSL www.bearssl.org 33 */ 34 35 #include <sys/time.h> 36 #include <stdarg.h> 37 #define NEED_BRSSL_H 38 #include "libsecureboot-priv.h" 39 #include <brssl.h> 40 #include <ta.h> 41 42 #ifndef TRUST_ANCHOR_STR 43 # define TRUST_ANCHOR_STR ta_PEM 44 #endif 45 46 #define EPOCH_YEAR 1970 47 #define AVG_SECONDS_PER_YEAR 31556952L 48 #define SECONDS_PER_DAY 86400 49 #define SECONDS_PER_YEAR 365 * SECONDS_PER_DAY 50 #ifndef VE_UTC_MAX_JUMP 51 # define VE_UTC_MAX_JUMP 20 * SECONDS_PER_YEAR 52 #endif 53 #define X509_DAYS_TO_UTC0 719528 54 55 int DebugVe = 0; 56 57 #ifndef VE_VERIFY_FLAGS 58 # define VE_VERIFY_FLAGS VEF_VERBOSE 59 #endif 60 int VerifyFlags = VE_VERIFY_FLAGS; 61 62 typedef VECTOR(br_x509_certificate) cert_list; 63 typedef VECTOR(hash_data) digest_list; 64 65 static anchor_list trust_anchors = VEC_INIT; 66 static anchor_list forbidden_anchors = VEC_INIT; 67 static digest_list forbidden_digests = VEC_INIT; 68 69 static int anchor_verbose = 0; 70 71 void 72 ve_anchor_verbose_set(int n) 73 { 74 anchor_verbose = n; 75 } 76 77 int 78 ve_anchor_verbose_get(void) 79 { 80 return (anchor_verbose); 81 } 82 83 void 84 ve_debug_set(int n) 85 { 86 DebugVe = n; 87 } 88 89 static char ebuf[512]; 90 91 char * 92 ve_error_get(void) 93 { 94 return (ebuf); 95 } 96 97 int 98 ve_error_set(const char *fmt, ...) 99 { 100 int rc; 101 va_list ap; 102 103 va_start(ap, fmt); 104 ebuf[0] = '\0'; 105 rc = 0; 106 if (fmt) { 107 #ifdef STAND_H 108 vsprintf(ebuf, fmt, ap); /* no vsnprintf in libstand */ 109 ebuf[sizeof(ebuf) - 1] = '\0'; 110 rc = strlen(ebuf); 111 #else 112 rc = vsnprintf(ebuf, sizeof(ebuf), fmt, ap); 113 #endif 114 } 115 va_end(ap); 116 return (rc); 117 } 118 119 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0)) 120 121 /* 122 * The *approximate* date. 123 * 124 * When certificate verification fails for being 125 * expired or not yet valid, it helps to indicate 126 * our current date. 127 * Since libsa lacks strftime and gmtime, 128 * this simple implementation suffices. 129 */ 130 static const char * 131 gdate(char *buf, size_t bufsz, time_t clock) 132 { 133 int days[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; 134 int year, y, m, d; 135 136 y = clock / AVG_SECONDS_PER_YEAR; 137 year = EPOCH_YEAR + y; 138 for (y = EPOCH_YEAR; y < year; y++) { 139 clock -= SECONDS_PER_YEAR; 140 if (isleap(y)) 141 clock -= SECONDS_PER_DAY; 142 } 143 d = clock / SECONDS_PER_DAY; 144 for (m = 0; d > 1 && m < 12; m++) { 145 if (d > days[m]) { 146 d -= days[m]; 147 if (m == 1 && d > 0 && isleap(year)) 148 d--; 149 } else 150 break; 151 } 152 d++; 153 if (d > days[m]) { 154 d = 1; 155 m++; 156 if (m >= 12) { 157 year++; 158 m = 0; 159 } 160 } 161 (void)snprintf(buf, bufsz, "%04d-%02d-%02d", year, m+1, d); 162 return(buf); 163 } 164 165 /* this is the time we use for verifying certs */ 166 #ifdef UNIT_TEST 167 extern time_t ve_utc; 168 time_t ve_utc = 0; 169 #else 170 static time_t ve_utc = 0; 171 #endif 172 173 /** 174 * @brief 175 * set ve_utc used for certificate verification 176 * 177 * @param[in] utc 178 * time - ignored unless greater than current value 179 * and not a leap of 20 years or more. 180 */ 181 void 182 ve_utc_set(time_t utc) 183 { 184 if (utc > ve_utc && 185 (ve_utc == 0 || (utc - ve_utc) < VE_UTC_MAX_JUMP)) { 186 DEBUG_PRINTF(2, ("Set ve_utc=%jd\n", (intmax_t)utc)); 187 ve_utc = utc; 188 } 189 } 190 191 static void 192 free_cert_contents(br_x509_certificate *xc) 193 { 194 xfree(xc->data); 195 } 196 197 /* 198 * a bit of a dance to get commonName from a certificate 199 */ 200 static char * 201 x509_cn_get(br_x509_certificate *xc, char *buf, size_t len) 202 { 203 br_x509_minimal_context mc; 204 br_name_element cn; 205 unsigned char cn_oid[4]; 206 int err; 207 208 if (buf == NULL) 209 return (buf); 210 /* 211 * We want the commonName field 212 * the OID we want is 2,5,4,3 - but DER encoded 213 */ 214 cn_oid[0] = 3; 215 cn_oid[1] = 0x55; 216 cn_oid[2] = 4; 217 cn_oid[3] = 3; 218 cn.oid = cn_oid; 219 cn.buf = buf; 220 cn.len = len; 221 cn.buf[0] = '\0'; 222 223 br_x509_minimal_init(&mc, &br_sha256_vtable, NULL, 0); 224 br_x509_minimal_set_name_elements(&mc, &cn, 1); 225 /* the below actually does the work - updates cn.status */ 226 mc.vtable->start_chain(&mc.vtable, NULL); 227 mc.vtable->start_cert(&mc.vtable, xc->data_len); 228 mc.vtable->append(&mc.vtable, xc->data, xc->data_len); 229 mc.vtable->end_cert(&mc.vtable); 230 /* we don' actually care about cert status - just its name */ 231 err = mc.vtable->end_chain(&mc.vtable); 232 233 if (!cn.status) 234 buf = NULL; 235 return (buf); 236 } 237 238 /* ASN parsing related defines */ 239 #define ASN1_PRIMITIVE_TAG 0x1F 240 #define ASN1_INF_LENGTH 0x80 241 #define ASN1_LENGTH_MASK 0x7F 242 243 /* 244 * Get TBS part of certificate. 245 * Since BearSSL doesn't provide any API to do this, 246 * it has to be implemented here. 247 */ 248 static void* 249 X509_to_tbs(unsigned char* cert, size_t* output_size) 250 { 251 unsigned char *result; 252 size_t tbs_size; 253 int size, i; 254 255 if (cert == NULL) 256 return (NULL); 257 258 /* Strip two sequences to get to the TBS section */ 259 for (i = 0; i < 2; i++) { 260 /* 261 * XXX: We don't need to support extended tags since 262 * they should not be present in certificates. 263 */ 264 if ((*cert & ASN1_PRIMITIVE_TAG) == ASN1_PRIMITIVE_TAG) 265 return (NULL); 266 267 cert++; 268 269 if (*cert == ASN1_INF_LENGTH) 270 return (NULL); 271 272 size = *cert & ASN1_LENGTH_MASK; 273 tbs_size = 0; 274 275 /* Size can either be stored on a single or multiple bytes */ 276 if (*cert & (ASN1_LENGTH_MASK + 1)) { 277 cert++; 278 while (*cert == 0 && size > 0) { 279 cert++; 280 size--; 281 } 282 while (size-- > 0) { 283 tbs_size <<= 8; 284 tbs_size |= *(cert++); 285 } 286 } 287 if (i == 0) 288 result = cert; 289 } 290 tbs_size += (cert - result); 291 292 if (output_size != NULL) 293 *output_size = tbs_size; 294 295 return (result); 296 } 297 298 void 299 ve_forbidden_digest_add(hash_data *digest, size_t num) 300 { 301 while (num--) 302 VEC_ADD(forbidden_digests, digest[num]); 303 } 304 305 static size_t 306 ve_anchors_add(br_x509_certificate *xcs, size_t num, anchor_list *anchors, 307 const char *anchors_name) 308 { 309 br_x509_trust_anchor ta; 310 size_t u; 311 312 for (u = 0; u < num; u++) { 313 if (certificate_to_trust_anchor_inner(&ta, &xcs[u]) < 0) { 314 break; 315 } 316 VEC_ADD(*anchors, ta); 317 if (anchor_verbose && anchors_name) { 318 char buf[64]; 319 char *cp; 320 321 cp = x509_cn_get(&xcs[u], buf, sizeof(buf)); 322 if (cp) { 323 printf("x509_anchor(%s) %s\n", cp, anchors_name); 324 } 325 } 326 } 327 return (u); 328 } 329 330 /** 331 * @brief 332 * add certs to our trust store 333 */ 334 size_t 335 ve_trust_anchors_add(br_x509_certificate *xcs, size_t num) 336 { 337 return (ve_anchors_add(xcs, num, &trust_anchors, "trusted")); 338 } 339 340 size_t 341 ve_forbidden_anchors_add(br_x509_certificate *xcs, size_t num) 342 { 343 return (ve_anchors_add(xcs, num, &forbidden_anchors, "forbidden")); 344 } 345 346 347 /** 348 * @brief add trust anchors in buf 349 * 350 * Assume buf contains x509 certificates, but if not and 351 * we support OpenPGP try adding as that. 352 * 353 * @return number of anchors added 354 */ 355 size_t 356 ve_trust_anchors_add_buf(unsigned char *buf, size_t len) 357 { 358 br_x509_certificate *xcs; 359 size_t num; 360 361 num = 0; 362 xcs = parse_certificates(buf, len, &num); 363 if (xcs != NULL) { 364 num = ve_trust_anchors_add(xcs, num); 365 #ifdef VE_OPENPGP_SUPPORT 366 } else { 367 num = openpgp_trust_add_buf(buf, len); 368 #endif 369 } 370 return (num); 371 } 372 373 /** 374 * @brief revoke trust anchors in buf 375 * 376 * Assume buf contains x509 certificates, but if not and 377 * we support OpenPGP try revoking keyId 378 * 379 * @return number of anchors revoked 380 */ 381 size_t 382 ve_trust_anchors_revoke(unsigned char *buf, size_t len) 383 { 384 br_x509_certificate *xcs; 385 size_t num; 386 387 num = 0; 388 xcs = parse_certificates(buf, len, &num); 389 if (xcs != NULL) { 390 num = ve_forbidden_anchors_add(xcs, num); 391 #ifdef VE_OPENPGP_SUPPORT 392 } else { 393 if (buf[len - 1] == '\n') 394 buf[len - 1] = '\0'; 395 num = openpgp_trust_revoke((char *)buf); 396 #endif 397 } 398 return (num); 399 } 400 401 /** 402 * @brief 403 * initialize our trust_anchors from ta_PEM 404 */ 405 int 406 ve_trust_init(void) 407 { 408 static int once = -1; 409 410 if (once >= 0) 411 return (once); 412 once = 0; /* to be sure */ 413 #ifdef BUILD_UTC 414 ve_utc_set(BUILD_UTC); /* ensure sanity */ 415 #endif 416 ve_utc_set(time(NULL)); 417 ve_error_set(NULL); /* make sure it is empty */ 418 #ifdef VE_PCR_SUPPORT 419 ve_pcr_init(); 420 #endif 421 422 #ifdef TRUST_ANCHOR_STR 423 ve_trust_anchors_add_buf(__DECONST(unsigned char *, TRUST_ANCHOR_STR), 424 sizeof(TRUST_ANCHOR_STR)); 425 #endif 426 once = (int) VEC_LEN(trust_anchors); 427 #ifdef VE_OPENPGP_SUPPORT 428 once += openpgp_trust_init(); 429 #endif 430 return (once); 431 } 432 433 #ifdef HAVE_BR_X509_TIME_CHECK 434 static int 435 verify_time_cb(void *tctx __unused, 436 uint32_t not_before_days, uint32_t not_before_seconds, 437 uint32_t not_after_days, uint32_t not_after_seconds) 438 { 439 time_t not_before; 440 time_t not_after; 441 int rc; 442 #ifdef UNIT_TEST 443 char date[12], nb_date[12], na_date[12]; 444 #endif 445 446 not_before = ((not_before_days - X509_DAYS_TO_UTC0) * SECONDS_PER_DAY) + not_before_seconds; 447 not_after = ((not_after_days - X509_DAYS_TO_UTC0) * SECONDS_PER_DAY) + not_after_seconds; 448 if (ve_utc < not_before) 449 rc = -1; 450 else if (ve_utc > not_after) 451 rc = 1; 452 else 453 rc = 0; 454 #ifdef UNIT_TEST 455 printf("notBefore %s notAfter %s date %s rc %d\n", 456 gdate(nb_date, sizeof(nb_date), not_before), 457 gdate(na_date, sizeof(na_date), not_after), 458 gdate(date, sizeof(date), ve_utc), rc); 459 #endif 460 #if defined(_STANDALONE) 461 rc = 0; /* don't fail */ 462 #endif 463 return rc; 464 } 465 #endif 466 467 /** 468 * if we can verify the certificate chain in "certs", 469 * return the public key and if "xcp" is !NULL the associated 470 * certificate 471 */ 472 static br_x509_pkey * 473 verify_signer_xcs(br_x509_certificate *xcs, 474 size_t num, 475 br_name_element *elts, size_t num_elts, 476 anchor_list *anchors) 477 { 478 br_x509_minimal_context mc; 479 br_x509_certificate *xc; 480 size_t u; 481 cert_list chain = VEC_INIT; 482 const br_x509_pkey *tpk; 483 br_x509_pkey *pk; 484 unsigned int usages; 485 int err; 486 487 DEBUG_PRINTF(5, ("verify_signer: %zu certs in chain\n", num)); 488 VEC_ADDMANY(chain, xcs, num); 489 if (VEC_LEN(chain) == 0) { 490 ve_error_set("ERROR: no/invalid certificate chain\n"); 491 return (NULL); 492 } 493 494 DEBUG_PRINTF(5, ("verify_signer: %zu trust anchors\n", 495 VEC_LEN(*anchors))); 496 497 br_x509_minimal_init(&mc, &br_sha256_vtable, 498 &VEC_ELT(*anchors, 0), 499 VEC_LEN(*anchors)); 500 #ifdef VE_ECDSA_SUPPORT 501 br_x509_minimal_set_ecdsa(&mc, 502 &br_ec_prime_i31, &br_ecdsa_i31_vrfy_asn1); 503 #endif 504 #ifdef VE_RSA_SUPPORT 505 br_x509_minimal_set_rsa(&mc, &br_rsa_i31_pkcs1_vrfy); 506 #endif 507 #if defined(UNIT_TEST) && defined(VE_DEPRECATED_RSA_SHA1_SUPPORT) 508 /* This is deprecated! do not enable unless you absoultely have to */ 509 br_x509_minimal_set_hash(&mc, br_sha1_ID, &br_sha1_vtable); 510 #endif 511 br_x509_minimal_set_hash(&mc, br_sha256_ID, &br_sha256_vtable); 512 #ifdef VE_SHA384_SUPPORT 513 br_x509_minimal_set_hash(&mc, br_sha384_ID, &br_sha384_vtable); 514 #endif 515 #ifdef VE_SHA512_SUPPORT 516 br_x509_minimal_set_hash(&mc, br_sha512_ID, &br_sha512_vtable); 517 #endif 518 br_x509_minimal_set_name_elements(&mc, elts, num_elts); 519 520 #ifdef HAVE_BR_X509_TIME_CHECK 521 br_x509_minimal_set_time_callback(&mc, NULL, verify_time_cb); 522 #else 523 #if defined(_STANDALONE) || defined(UNIT_TEST) 524 /* 525 * Clock is probably bogus so we use ve_utc. 526 */ 527 mc.days = (ve_utc / SECONDS_PER_DAY) + X509_DAYS_TO_UTC0; 528 mc.seconds = (ve_utc % SECONDS_PER_DAY); 529 #endif 530 #endif 531 mc.vtable->start_chain(&mc.vtable, NULL); 532 for (u = 0; u < VEC_LEN(chain); u ++) { 533 xc = &VEC_ELT(chain, u); 534 mc.vtable->start_cert(&mc.vtable, xc->data_len); 535 mc.vtable->append(&mc.vtable, xc->data, xc->data_len); 536 mc.vtable->end_cert(&mc.vtable); 537 switch (mc.err) { 538 case 0: 539 case BR_ERR_X509_OK: 540 case BR_ERR_X509_EXPIRED: 541 break; 542 default: 543 printf("u=%zu mc.err=%d\n", u, mc.err); 544 break; 545 } 546 } 547 err = mc.vtable->end_chain(&mc.vtable); 548 pk = NULL; 549 if (err) { 550 char date[12]; 551 552 switch (err) { 553 case 54: 554 ve_error_set("Validation failed, certificate not valid as of %s", 555 gdate(date, sizeof(date), ve_utc)); 556 break; 557 default: 558 ve_error_set("Validation failed, err = %d", err); 559 break; 560 } 561 } else { 562 tpk = mc.vtable->get_pkey(&mc.vtable, &usages); 563 if (tpk != NULL) { 564 pk = xpkeydup(tpk); 565 } 566 } 567 VEC_CLEAR(chain); 568 return (pk); 569 } 570 571 /* 572 * Check if digest of one of the certificates from verified chain 573 * is present in the forbidden database. 574 * Since UEFI allows to store three types of digests 575 * all of them have to be checked separately. 576 */ 577 static int 578 check_forbidden_digests(br_x509_certificate *xcs, size_t num) 579 { 580 unsigned char sha256_digest[br_sha256_SIZE]; 581 unsigned char sha384_digest[br_sha384_SIZE]; 582 unsigned char sha512_digest[br_sha512_SIZE]; 583 void *tbs; 584 hash_data *digest; 585 br_hash_compat_context ctx; 586 const br_hash_class *md; 587 size_t tbs_len, i; 588 int have_sha256, have_sha384, have_sha512; 589 590 if (VEC_LEN(forbidden_digests) == 0) 591 return (0); 592 593 /* 594 * Iterate through certificates, extract their To-Be-Signed section, 595 * and compare its digest against the ones in the forbidden database. 596 */ 597 while (num--) { 598 tbs = X509_to_tbs(xcs[num].data, &tbs_len); 599 if (tbs == NULL) { 600 printf("Failed to obtain TBS part of certificate\n"); 601 return (1); 602 } 603 have_sha256 = have_sha384 = have_sha512 = 0; 604 605 for (i = 0; i < VEC_LEN(forbidden_digests); i++) { 606 digest = &VEC_ELT(forbidden_digests, i); 607 switch (digest->hash_size) { 608 case br_sha256_SIZE: 609 if (!have_sha256) { 610 have_sha256 = 1; 611 md = &br_sha256_vtable; 612 md->init(&ctx.vtable); 613 md->update(&ctx.vtable, tbs, tbs_len); 614 md->out(&ctx.vtable, sha256_digest); 615 } 616 if (!memcmp(sha256_digest, 617 digest->data, 618 br_sha256_SIZE)) 619 return (1); 620 621 break; 622 case br_sha384_SIZE: 623 if (!have_sha384) { 624 have_sha384 = 1; 625 md = &br_sha384_vtable; 626 md->init(&ctx.vtable); 627 md->update(&ctx.vtable, tbs, tbs_len); 628 md->out(&ctx.vtable, sha384_digest); 629 } 630 if (!memcmp(sha384_digest, 631 digest->data, 632 br_sha384_SIZE)) 633 return (1); 634 635 break; 636 case br_sha512_SIZE: 637 if (!have_sha512) { 638 have_sha512 = 1; 639 md = &br_sha512_vtable; 640 md->init(&ctx.vtable); 641 md->update(&ctx.vtable, tbs, tbs_len); 642 md->out(&ctx.vtable, sha512_digest); 643 } 644 if (!memcmp(sha512_digest, 645 digest->data, 646 br_sha512_SIZE)) 647 return (1); 648 649 break; 650 } 651 } 652 } 653 654 return (0); 655 } 656 657 static br_x509_pkey * 658 verify_signer(const char *certs, 659 br_name_element *elts, size_t num_elts) 660 { 661 br_x509_certificate *xcs; 662 br_x509_pkey *pk; 663 size_t num; 664 665 pk = NULL; 666 667 ve_trust_init(); 668 xcs = read_certificates(certs, &num); 669 if (xcs == NULL) { 670 ve_error_set("cannot read certificates\n"); 671 return (NULL); 672 } 673 674 /* 675 * Check if either 676 * 1. There is a direct match between cert from forbidden_anchors 677 * and a cert from chain. 678 * 2. CA that signed the chain is found in forbidden_anchors. 679 */ 680 if (VEC_LEN(forbidden_anchors) > 0) 681 pk = verify_signer_xcs(xcs, num, elts, num_elts, &forbidden_anchors); 682 if (pk != NULL) { 683 ve_error_set("Certificate is on forbidden list\n"); 684 xfreepkey(pk); 685 pk = NULL; 686 goto out; 687 } 688 689 pk = verify_signer_xcs(xcs, num, elts, num_elts, &trust_anchors); 690 if (pk == NULL) 691 goto out; 692 693 /* 694 * Check if hash of tbs part of any certificate in chain 695 * is on the forbidden list. 696 */ 697 if (check_forbidden_digests(xcs, num)) { 698 ve_error_set("Certificate hash is on forbidden list\n"); 699 xfreepkey(pk); 700 pk = NULL; 701 } 702 out: 703 free_certificates(xcs, num); 704 return (pk); 705 } 706 707 /** 708 * we need a hex digest including trailing newline below 709 */ 710 char * 711 hexdigest(char *buf, size_t bufsz, unsigned char *foo, size_t foo_len) 712 { 713 char const hex2ascii[] = "0123456789abcdef"; 714 size_t i; 715 716 /* every binary byte is 2 chars in hex + newline + null */ 717 if (bufsz < (2 * foo_len) + 2) 718 return (NULL); 719 720 for (i = 0; i < foo_len; i++) { 721 buf[i * 2] = hex2ascii[foo[i] >> 4]; 722 buf[i * 2 + 1] = hex2ascii[foo[i] & 0x0f]; 723 } 724 725 buf[i * 2] = 0x0A; /* we also want a newline */ 726 buf[i * 2 + 1] = '\0'; 727 728 return (buf); 729 } 730 731 /** 732 * @brief 733 * verify file against sigfile using pk 734 * 735 * When we generated the signature in sigfile, 736 * we hashed (sha256) file, and sent that to signing server 737 * which hashed (sha256) that hash. 738 * 739 * To verify we need to replicate that result. 740 * 741 * @param[in] pk 742 * br_x509_pkey 743 * 744 * @paramp[in] file 745 * file to be verified 746 * 747 * @param[in] sigfile 748 * signature (PEM encoded) 749 * 750 * @return NULL on error, otherwise content of file. 751 */ 752 #ifdef VE_ECDSA_SUPPORT 753 static unsigned char * 754 verify_ec(br_x509_pkey *pk, const char *file, const char *sigfile) 755 { 756 #ifdef VE_ECDSA_HASH_AGAIN 757 char *hex, hexbuf[br_sha512_SIZE * 2 + 2]; 758 #endif 759 unsigned char rhbuf[br_sha512_SIZE]; 760 br_sha256_context ctx; 761 unsigned char *fcp, *scp; 762 size_t flen, slen, plen; 763 pem_object *po; 764 const br_ec_impl *ec; 765 br_ecdsa_vrfy vrfy; 766 767 if ((fcp = read_file(file, &flen)) == NULL) 768 return (NULL); 769 if ((scp = read_file(sigfile, &slen)) == NULL) { 770 free(fcp); 771 return (NULL); 772 } 773 if ((po = decode_pem(scp, slen, &plen)) == NULL) { 774 free(fcp); 775 free(scp); 776 return (NULL); 777 } 778 br_sha256_init(&ctx); 779 br_sha256_update(&ctx, fcp, flen); 780 br_sha256_out(&ctx, rhbuf); 781 #ifdef VE_ECDSA_HASH_AGAIN 782 hex = hexdigest(hexbuf, sizeof(hexbuf), rhbuf, br_sha256_SIZE); 783 /* now hash that */ 784 if (hex) { 785 br_sha256_init(&ctx); 786 br_sha256_update(&ctx, hex, strlen(hex)); 787 br_sha256_out(&ctx, rhbuf); 788 } 789 #endif 790 ec = br_ec_get_default(); 791 vrfy = br_ecdsa_vrfy_asn1_get_default(); 792 if (!vrfy(ec, rhbuf, br_sha256_SIZE, &pk->key.ec, po->data, 793 po->data_len)) { 794 free(fcp); 795 fcp = NULL; 796 } 797 free(scp); 798 return (fcp); 799 } 800 #endif 801 802 #if defined(VE_RSA_SUPPORT) || defined(VE_OPENPGP_SUPPORT) 803 /** 804 * @brief verify an rsa digest 805 * 806 * @return 0 on failure 807 */ 808 int 809 verify_rsa_digest (br_rsa_public_key *pkey, 810 const unsigned char *hash_oid, 811 unsigned char *mdata, size_t mlen, 812 unsigned char *sdata, size_t slen) 813 { 814 br_rsa_pkcs1_vrfy vrfy; 815 unsigned char vhbuf[br_sha512_SIZE]; 816 817 vrfy = br_rsa_pkcs1_vrfy_get_default(); 818 819 if (!vrfy(sdata, slen, hash_oid, mlen, pkey, vhbuf) || 820 memcmp(vhbuf, mdata, mlen) != 0) { 821 return (0); /* fail */ 822 } 823 return (1); /* ok */ 824 } 825 #endif 826 827 /** 828 * @brief 829 * verify file against sigfile using pk 830 * 831 * When we generated the signature in sigfile, 832 * we hashed (sha256) file, and sent that to signing server 833 * which hashed (sha256) that hash. 834 * 835 * Or (deprecated) we simply used sha1 hash directly. 836 * 837 * To verify we need to replicate that result. 838 * 839 * @param[in] pk 840 * br_x509_pkey 841 * 842 * @paramp[in] file 843 * file to be verified 844 * 845 * @param[in] sigfile 846 * signature (PEM encoded) 847 * 848 * @return NULL on error, otherwise content of file. 849 */ 850 #ifdef VE_RSA_SUPPORT 851 static unsigned char * 852 verify_rsa(br_x509_pkey *pk, const char *file, const char *sigfile) 853 { 854 unsigned char rhbuf[br_sha512_SIZE]; 855 const unsigned char *hash_oid; 856 const br_hash_class *md; 857 br_hash_compat_context mctx; 858 unsigned char *fcp, *scp; 859 size_t flen, slen, plen, hlen; 860 pem_object *po; 861 862 if ((fcp = read_file(file, &flen)) == NULL) 863 return (NULL); 864 if ((scp = read_file(sigfile, &slen)) == NULL) { 865 free(fcp); 866 return (NULL); 867 } 868 if ((po = decode_pem(scp, slen, &plen)) == NULL) { 869 free(fcp); 870 free(scp); 871 return (NULL); 872 } 873 874 switch (po->data_len) { 875 #if defined(UNIT_TEST) && defined(VE_DEPRECATED_RSA_SHA1_SUPPORT) 876 case 256: 877 // this is our old deprecated sig method 878 md = &br_sha1_vtable; 879 hlen = br_sha1_SIZE; 880 hash_oid = BR_HASH_OID_SHA1; 881 break; 882 #endif 883 default: 884 md = &br_sha256_vtable; 885 hlen = br_sha256_SIZE; 886 hash_oid = BR_HASH_OID_SHA256; 887 break; 888 } 889 md->init(&mctx.vtable); 890 md->update(&mctx.vtable, fcp, flen); 891 md->out(&mctx.vtable, rhbuf); 892 if (!verify_rsa_digest(&pk->key.rsa, hash_oid, 893 rhbuf, hlen, po->data, po->data_len)) { 894 free(fcp); 895 fcp = NULL; 896 } 897 free(scp); 898 return (fcp); 899 } 900 #endif 901 902 /** 903 * @brief 904 * verify a signature and return content of signed file 905 * 906 * @param[in] sigfile 907 * file containing signature 908 * we derrive path of signed file and certificate change from 909 * this. 910 * 911 * @param[in] flags 912 * only bit 1 significant so far 913 * 914 * @return NULL on error otherwise content of signed file 915 */ 916 unsigned char * 917 verify_sig(const char *sigfile, int flags) 918 { 919 br_x509_pkey *pk; 920 br_name_element cn; 921 char cn_buf[80]; 922 unsigned char cn_oid[4]; 923 char pbuf[MAXPATHLEN]; 924 char *cp; 925 unsigned char *ucp; 926 size_t n; 927 928 DEBUG_PRINTF(5, ("verify_sig: %s\n", sigfile)); 929 n = strlcpy(pbuf, sigfile, sizeof(pbuf)); 930 if (n > (sizeof(pbuf) - 5) || strcmp(&sigfile[n - 3], "sig") != 0) 931 return (NULL); 932 cp = strcpy(&pbuf[n - 3], "certs"); 933 /* 934 * We want the commonName field 935 * the OID we want is 2,5,4,3 - but DER encoded 936 */ 937 cn_oid[0] = 3; 938 cn_oid[1] = 0x55; 939 cn_oid[2] = 4; 940 cn_oid[3] = 3; 941 cn.oid = cn_oid; 942 cn.buf = cn_buf; 943 cn.len = sizeof(cn_buf); 944 945 pk = verify_signer(pbuf, &cn, 1); 946 if (!pk) { 947 printf("cannot verify: %s: %s\n", pbuf, ve_error_get()); 948 return (NULL); 949 } 950 for (; cp > pbuf; cp--) { 951 if (*cp == '.') { 952 *cp = '\0'; 953 break; 954 } 955 } 956 switch (pk->key_type) { 957 #ifdef VE_ECDSA_SUPPORT 958 case BR_KEYTYPE_EC: 959 ucp = verify_ec(pk, pbuf, sigfile); 960 break; 961 #endif 962 #ifdef VE_RSA_SUPPORT 963 case BR_KEYTYPE_RSA: 964 ucp = verify_rsa(pk, pbuf, sigfile); 965 break; 966 #endif 967 default: 968 ucp = NULL; /* not supported */ 969 } 970 xfreepkey(pk); 971 if (!ucp) { 972 printf("Unverified %s (%s)\n", pbuf, 973 cn.status ? cn_buf : "unknown"); 974 } else if ((flags & VEF_VERBOSE) != 0) { 975 printf("Verified %s signed by %s\n", pbuf, 976 cn.status ? cn_buf : "someone we trust"); 977 } 978 return (ucp); 979 } 980 981 982 /** 983 * @brief verify hash matches 984 * 985 * We have finished hashing a file, 986 * see if we got the desired result. 987 * 988 * @param[in] ctx 989 * pointer to hash context 990 * 991 * @param[in] md 992 * pointer to hash class 993 * 994 * @param[in] path 995 * name of the file we are checking 996 * 997 * @param[in] want 998 * the expected result 999 * 1000 * @param[in] hlen 1001 * size of hash output 1002 * 1003 * @return 0 on success 1004 */ 1005 int 1006 ve_check_hash(br_hash_compat_context *ctx, const br_hash_class *md, 1007 const char *path, const char *want, size_t hlen) 1008 { 1009 char hexbuf[br_sha512_SIZE * 2 + 2]; 1010 unsigned char hbuf[br_sha512_SIZE]; 1011 char *hex; 1012 int rc; 1013 int n; 1014 1015 md->out(&ctx->vtable, hbuf); 1016 #ifdef VE_PCR_SUPPORT 1017 ve_pcr_update(path, hbuf, hlen); 1018 #endif 1019 hex = hexdigest(hexbuf, sizeof(hexbuf), hbuf, hlen); 1020 if (!hex) 1021 return (VE_FINGERPRINT_WRONG); 1022 n = 2*hlen; 1023 if ((rc = strncmp(hex, want, n))) { 1024 ve_error_set("%s: %.*s != %.*s", path, n, hex, n, want); 1025 rc = VE_FINGERPRINT_WRONG; 1026 } 1027 return (rc ? rc : VE_FINGERPRINT_OK); 1028 } 1029 1030 #ifdef VE_HASH_KAT_STR 1031 static int 1032 test_hash(const br_hash_class *md, size_t hlen, 1033 const char *hname, const char *s, size_t slen, const char *want) 1034 { 1035 br_hash_compat_context mctx; 1036 1037 md->init(&mctx.vtable); 1038 md->update(&mctx.vtable, s, slen); 1039 return (ve_check_hash(&mctx, md, hname, want, hlen) != VE_FINGERPRINT_OK); 1040 } 1041 1042 #endif 1043 1044 #define ve_test_hash(n, N) \ 1045 printf("Testing hash: " #n "\t\t\t\t%s\n", \ 1046 test_hash(&br_ ## n ## _vtable, br_ ## n ## _SIZE, #n, \ 1047 VE_HASH_KAT_STR, VE_HASH_KAT_STRLEN(VE_HASH_KAT_STR), \ 1048 vh_ ## N) ? "Failed" : "Passed") 1049 1050 /** 1051 * @brief 1052 * run self tests on hash and signature verification 1053 * 1054 * Test that the hash methods (SHA1 and SHA256) work. 1055 * Test that we can verify a certificate for each supported 1056 * Root CA. 1057 * 1058 * @return cached result. 1059 */ 1060 int 1061 ve_self_tests(void) 1062 { 1063 static int once = -1; 1064 #ifdef VERIFY_CERTS_STR 1065 br_x509_certificate *xcs; 1066 br_x509_pkey *pk; 1067 br_name_element cn; 1068 char cn_buf[80]; 1069 unsigned char cn_oid[4]; 1070 size_t num; 1071 size_t u; 1072 #endif 1073 1074 if (once >= 0) 1075 return (once); 1076 once = 0; 1077 1078 DEBUG_PRINTF(5, ("Self tests...\n")); 1079 #ifdef VE_HASH_KAT_STR 1080 #ifdef VE_SHA1_SUPPORT 1081 ve_test_hash(sha1, SHA1); 1082 #endif 1083 #ifdef VE_SHA256_SUPPORT 1084 ve_test_hash(sha256, SHA256); 1085 #endif 1086 #ifdef VE_SHA384_SUPPORT 1087 ve_test_hash(sha384, SHA384); 1088 #endif 1089 #ifdef VE_SHA512_SUPPORT 1090 ve_test_hash(sha512, SHA512); 1091 #endif 1092 #endif 1093 #ifdef VERIFY_CERTS_STR 1094 xcs = parse_certificates(__DECONST(unsigned char *, VERIFY_CERTS_STR), 1095 sizeof(VERIFY_CERTS_STR), &num); 1096 if (xcs != NULL) { 1097 /* 1098 * We want the commonName field 1099 * the OID we want is 2,5,4,3 - but DER encoded 1100 */ 1101 cn_oid[0] = 3; 1102 cn_oid[1] = 0x55; 1103 cn_oid[2] = 4; 1104 cn_oid[3] = 3; 1105 cn.oid = cn_oid; 1106 cn.buf = cn_buf; 1107 1108 for (u = 0; u < num; u ++) { 1109 cn.len = sizeof(cn_buf); 1110 if ((pk = verify_signer_xcs(&xcs[u], 1, &cn, 1, &trust_anchors)) != NULL) { 1111 free_cert_contents(&xcs[u]); 1112 once++; 1113 printf("Testing verify certificate: %s\tPassed\n", 1114 cn.status ? cn_buf : ""); 1115 xfreepkey(pk); 1116 } 1117 } 1118 if (!once) 1119 printf("Testing verify certificate:\t\t\tFailed\n"); 1120 xfree(xcs); 1121 } 1122 #endif /* VERIFY_CERTS_STR */ 1123 #ifdef VE_OPENPGP_SUPPORT 1124 if (!openpgp_self_tests()) 1125 once++; 1126 #endif 1127 return (once); 1128 } 1129