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 /* 90 * For embedded systems (and boot loaders) 91 * we do not want to enforce certificate validity post install. 92 * It is generally unacceptible for infrastructure to stop working 93 * just because it has not been updated recently. 94 */ 95 static int enforce_validity = 0; 96 97 void 98 ve_enforce_validity_set(int i) 99 { 100 enforce_validity = i; 101 } 102 103 static char ebuf[512]; 104 105 char * 106 ve_error_get(void) 107 { 108 return (ebuf); 109 } 110 111 int 112 ve_error_set(const char *fmt, ...) 113 { 114 int rc; 115 va_list ap; 116 117 va_start(ap, fmt); 118 ebuf[0] = '\0'; 119 rc = 0; 120 if (fmt) { 121 #ifdef STAND_H 122 vsprintf(ebuf, fmt, ap); /* no vsnprintf in libstand */ 123 ebuf[sizeof(ebuf) - 1] = '\0'; 124 rc = strlen(ebuf); 125 #else 126 rc = vsnprintf(ebuf, sizeof(ebuf), fmt, ap); 127 #endif 128 } 129 va_end(ap); 130 return (rc); 131 } 132 133 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0)) 134 135 /* 136 * The *approximate* date. 137 * 138 * When certificate verification fails for being 139 * expired or not yet valid, it helps to indicate 140 * our current date. 141 * Since libsa lacks strftime and gmtime, 142 * this simple implementation suffices. 143 */ 144 static const char * 145 gdate(char *buf, size_t bufsz, time_t clock) 146 { 147 int days[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; 148 int year, y, m, d; 149 150 y = clock / AVG_SECONDS_PER_YEAR; 151 year = EPOCH_YEAR + y; 152 for (y = EPOCH_YEAR; y < year; y++) { 153 clock -= SECONDS_PER_YEAR; 154 if (isleap(y)) 155 clock -= SECONDS_PER_DAY; 156 } 157 d = clock / SECONDS_PER_DAY; 158 for (m = 0; d > 1 && m < 12; m++) { 159 if (d > days[m]) { 160 d -= days[m]; 161 if (m == 1 && d > 0 && isleap(year)) 162 d--; 163 } else 164 break; 165 } 166 d++; 167 if (d > days[m]) { 168 d = 1; 169 m++; 170 if (m >= 12) { 171 year++; 172 m = 0; 173 } 174 } 175 (void)snprintf(buf, bufsz, "%04d-%02d-%02d", year, m+1, d); 176 return(buf); 177 } 178 179 /* this is the time we use for verifying certs */ 180 #ifdef UNIT_TEST 181 extern time_t ve_utc; 182 time_t ve_utc = 0; 183 #else 184 static time_t ve_utc = 0; 185 #endif 186 187 /** 188 * @brief 189 * set ve_utc used for certificate verification 190 * 191 * @param[in] utc 192 * time - ignored unless greater than current value 193 * and not a leap of 20 years or more. 194 */ 195 void 196 ve_utc_set(time_t utc) 197 { 198 if (utc > ve_utc && 199 (ve_utc == 0 || (utc - ve_utc) < VE_UTC_MAX_JUMP)) { 200 DEBUG_PRINTF(2, ("Set ve_utc=%jd\n", (intmax_t)utc)); 201 ve_utc = utc; 202 } 203 } 204 205 static void 206 free_cert_contents(br_x509_certificate *xc) 207 { 208 xfree(xc->data); 209 } 210 211 /* 212 * a bit of a dance to get commonName from a certificate 213 */ 214 static char * 215 x509_cn_get(br_x509_certificate *xc, char *buf, size_t len) 216 { 217 br_x509_minimal_context mc; 218 br_name_element cn; 219 unsigned char cn_oid[4]; 220 int err; 221 222 if (buf == NULL) 223 return (buf); 224 /* 225 * We want the commonName field 226 * the OID we want is 2,5,4,3 - but DER encoded 227 */ 228 cn_oid[0] = 3; 229 cn_oid[1] = 0x55; 230 cn_oid[2] = 4; 231 cn_oid[3] = 3; 232 cn.oid = cn_oid; 233 cn.buf = buf; 234 cn.len = len; 235 cn.buf[0] = '\0'; 236 237 br_x509_minimal_init(&mc, &br_sha256_vtable, NULL, 0); 238 br_x509_minimal_set_name_elements(&mc, &cn, 1); 239 /* the below actually does the work - updates cn.status */ 240 mc.vtable->start_chain(&mc.vtable, NULL); 241 mc.vtable->start_cert(&mc.vtable, xc->data_len); 242 mc.vtable->append(&mc.vtable, xc->data, xc->data_len); 243 mc.vtable->end_cert(&mc.vtable); 244 /* we don' actually care about cert status - just its name */ 245 err = mc.vtable->end_chain(&mc.vtable); 246 247 if (!cn.status) 248 buf = NULL; 249 return (buf); 250 } 251 252 /* ASN parsing related defines */ 253 #define ASN1_PRIMITIVE_TAG 0x1F 254 #define ASN1_INF_LENGTH 0x80 255 #define ASN1_LENGTH_MASK 0x7F 256 257 /* 258 * Get TBS part of certificate. 259 * Since BearSSL doesn't provide any API to do this, 260 * it has to be implemented here. 261 */ 262 static void* 263 X509_to_tbs(unsigned char* cert, size_t* output_size) 264 { 265 unsigned char *result; 266 size_t tbs_size; 267 int size, i; 268 269 if (cert == NULL) 270 return (NULL); 271 272 /* Strip two sequences to get to the TBS section */ 273 for (i = 0; i < 2; i++) { 274 /* 275 * XXX: We don't need to support extended tags since 276 * they should not be present in certificates. 277 */ 278 if ((*cert & ASN1_PRIMITIVE_TAG) == ASN1_PRIMITIVE_TAG) 279 return (NULL); 280 281 cert++; 282 283 if (*cert == ASN1_INF_LENGTH) 284 return (NULL); 285 286 size = *cert & ASN1_LENGTH_MASK; 287 tbs_size = 0; 288 289 /* Size can either be stored on a single or multiple bytes */ 290 if (*cert & (ASN1_LENGTH_MASK + 1)) { 291 cert++; 292 while (*cert == 0 && size > 0) { 293 cert++; 294 size--; 295 } 296 while (size-- > 0) { 297 tbs_size <<= 8; 298 tbs_size |= *(cert++); 299 } 300 } 301 if (i == 0) 302 result = cert; 303 } 304 tbs_size += (cert - result); 305 306 if (output_size != NULL) 307 *output_size = tbs_size; 308 309 return (result); 310 } 311 312 void 313 ve_forbidden_digest_add(hash_data *digest, size_t num) 314 { 315 while (num--) 316 VEC_ADD(forbidden_digests, digest[num]); 317 } 318 319 static size_t 320 ve_anchors_add(br_x509_certificate *xcs, size_t num, anchor_list *anchors, 321 const char *anchors_name) 322 { 323 br_x509_trust_anchor ta; 324 size_t u; 325 326 for (u = 0; u < num; u++) { 327 if (certificate_to_trust_anchor_inner(&ta, &xcs[u]) < 0) { 328 break; 329 } 330 VEC_ADD(*anchors, ta); 331 if (anchor_verbose && anchors_name) { 332 char buf[64]; 333 char *cp; 334 335 cp = x509_cn_get(&xcs[u], buf, sizeof(buf)); 336 if (cp) { 337 printf("x509_anchor(%s) %s\n", cp, anchors_name); 338 } 339 } 340 } 341 return (u); 342 } 343 344 /** 345 * @brief 346 * add certs to our trust store 347 */ 348 size_t 349 ve_trust_anchors_add(br_x509_certificate *xcs, size_t num) 350 { 351 return (ve_anchors_add(xcs, num, &trust_anchors, "trusted")); 352 } 353 354 size_t 355 ve_forbidden_anchors_add(br_x509_certificate *xcs, size_t num) 356 { 357 return (ve_anchors_add(xcs, num, &forbidden_anchors, "forbidden")); 358 } 359 360 361 /** 362 * @brief add trust anchors in buf 363 * 364 * Assume buf contains x509 certificates, but if not and 365 * we support OpenPGP try adding as that. 366 * 367 * @return number of anchors added 368 */ 369 size_t 370 ve_trust_anchors_add_buf(unsigned char *buf, size_t len) 371 { 372 br_x509_certificate *xcs; 373 size_t num; 374 375 num = 0; 376 xcs = parse_certificates(buf, len, &num); 377 if (xcs != NULL) { 378 num = ve_trust_anchors_add(xcs, num); 379 #ifdef VE_OPENPGP_SUPPORT 380 } else { 381 num = openpgp_trust_add_buf(buf, len); 382 #endif 383 } 384 return (num); 385 } 386 387 /** 388 * @brief revoke trust anchors in buf 389 * 390 * Assume buf contains x509 certificates, but if not and 391 * we support OpenPGP try revoking keyId 392 * 393 * @return number of anchors revoked 394 */ 395 size_t 396 ve_trust_anchors_revoke(unsigned char *buf, size_t len) 397 { 398 br_x509_certificate *xcs; 399 size_t num; 400 401 num = 0; 402 xcs = parse_certificates(buf, len, &num); 403 if (xcs != NULL) { 404 num = ve_forbidden_anchors_add(xcs, num); 405 #ifdef VE_OPENPGP_SUPPORT 406 } else { 407 if (buf[len - 1] == '\n') 408 buf[len - 1] = '\0'; 409 num = openpgp_trust_revoke((char *)buf); 410 #endif 411 } 412 return (num); 413 } 414 415 /** 416 * @brief 417 * initialize our trust_anchors from ta_PEM 418 */ 419 int 420 ve_trust_init(void) 421 { 422 static int once = -1; 423 424 if (once >= 0) 425 return (once); 426 once = 0; /* to be sure */ 427 #ifdef BUILD_UTC 428 ve_utc_set(BUILD_UTC); /* ensure sanity */ 429 #endif 430 ve_utc_set(time(NULL)); 431 ve_error_set(NULL); /* make sure it is empty */ 432 #ifdef VE_PCR_SUPPORT 433 ve_pcr_init(); 434 #endif 435 436 #ifdef TRUST_ANCHOR_STR 437 if (TRUST_ANCHOR_STR != NULL && strlen(TRUST_ANCHOR_STR) != 0ul) 438 ve_trust_anchors_add_buf(__DECONST(unsigned char *, 439 TRUST_ANCHOR_STR), sizeof(TRUST_ANCHOR_STR)); 440 #endif 441 once = (int) VEC_LEN(trust_anchors); 442 #ifdef VE_OPENPGP_SUPPORT 443 once += openpgp_trust_init(); 444 #endif 445 return (once); 446 } 447 448 #ifdef HAVE_BR_X509_TIME_CHECK 449 static int 450 verify_time_cb(void *tctx __unused, 451 uint32_t not_before_days, uint32_t not_before_seconds, 452 uint32_t not_after_days, uint32_t not_after_seconds) 453 { 454 time_t not_before; 455 time_t not_after; 456 int rc; 457 #ifdef UNIT_TEST 458 char date[12], nb_date[12], na_date[12]; 459 #endif 460 461 if (enforce_validity) { 462 not_before = ((not_before_days - X509_DAYS_TO_UTC0) * SECONDS_PER_DAY) + not_before_seconds; 463 not_after = ((not_after_days - X509_DAYS_TO_UTC0) * SECONDS_PER_DAY) + not_after_seconds; 464 if (ve_utc < not_before) 465 rc = -1; 466 else if (ve_utc > not_after) 467 rc = 1; 468 else 469 rc = 0; 470 #ifdef UNIT_TEST 471 printf("notBefore %s notAfter %s date %s rc %d\n", 472 gdate(nb_date, sizeof(nb_date), not_before), 473 gdate(na_date, sizeof(na_date), not_after), 474 gdate(date, sizeof(date), ve_utc), rc); 475 #endif 476 } else 477 rc = 0; /* don't fail */ 478 return rc; 479 } 480 #endif 481 482 /** 483 * if we can verify the certificate chain in "certs", 484 * return the public key and if "xcp" is !NULL the associated 485 * certificate 486 */ 487 static br_x509_pkey * 488 verify_signer_xcs(br_x509_certificate *xcs, 489 size_t num, 490 br_name_element *elts, size_t num_elts, 491 anchor_list *anchors) 492 { 493 br_x509_minimal_context mc; 494 br_x509_certificate *xc; 495 size_t u; 496 cert_list chain = VEC_INIT; 497 const br_x509_pkey *tpk; 498 br_x509_pkey *pk; 499 unsigned int usages; 500 int err; 501 502 DEBUG_PRINTF(5, ("verify_signer: %zu certs in chain\n", num)); 503 VEC_ADDMANY(chain, xcs, num); 504 if (VEC_LEN(chain) == 0) { 505 ve_error_set("ERROR: no/invalid certificate chain\n"); 506 return (NULL); 507 } 508 509 DEBUG_PRINTF(5, ("verify_signer: %zu trust anchors\n", 510 VEC_LEN(*anchors))); 511 512 br_x509_minimal_init(&mc, &br_sha256_vtable, 513 &VEC_ELT(*anchors, 0), 514 VEC_LEN(*anchors)); 515 #ifdef VE_ECDSA_SUPPORT 516 br_x509_minimal_set_ecdsa(&mc, 517 &br_ec_prime_i31, &br_ecdsa_i31_vrfy_asn1); 518 #endif 519 #ifdef VE_RSA_SUPPORT 520 br_x509_minimal_set_rsa(&mc, &br_rsa_i31_pkcs1_vrfy); 521 #endif 522 #if defined(UNIT_TEST) && defined(VE_DEPRECATED_RSA_SHA1_SUPPORT) 523 /* This is deprecated! do not enable unless you absolutely have to */ 524 br_x509_minimal_set_hash(&mc, br_sha1_ID, &br_sha1_vtable); 525 #endif 526 br_x509_minimal_set_hash(&mc, br_sha256_ID, &br_sha256_vtable); 527 #ifdef VE_SHA384_SUPPORT 528 br_x509_minimal_set_hash(&mc, br_sha384_ID, &br_sha384_vtable); 529 #endif 530 #ifdef VE_SHA512_SUPPORT 531 br_x509_minimal_set_hash(&mc, br_sha512_ID, &br_sha512_vtable); 532 #endif 533 br_x509_minimal_set_name_elements(&mc, elts, num_elts); 534 535 #ifdef HAVE_BR_X509_TIME_CHECK 536 br_x509_minimal_set_time_callback(&mc, NULL, verify_time_cb); 537 #else 538 #if defined(_STANDALONE) || defined(UNIT_TEST) 539 /* 540 * Clock is probably bogus so we use ve_utc. 541 */ 542 mc.days = (ve_utc / SECONDS_PER_DAY) + X509_DAYS_TO_UTC0; 543 mc.seconds = (ve_utc % SECONDS_PER_DAY); 544 #endif 545 #endif 546 mc.vtable->start_chain(&mc.vtable, NULL); 547 for (u = 0; u < VEC_LEN(chain); u ++) { 548 xc = &VEC_ELT(chain, u); 549 mc.vtable->start_cert(&mc.vtable, xc->data_len); 550 mc.vtable->append(&mc.vtable, xc->data, xc->data_len); 551 mc.vtable->end_cert(&mc.vtable); 552 switch (mc.err) { 553 case 0: 554 case BR_ERR_X509_OK: 555 case BR_ERR_X509_EXPIRED: 556 break; 557 default: 558 printf("u=%zu mc.err=%d\n", u, mc.err); 559 break; 560 } 561 } 562 err = mc.vtable->end_chain(&mc.vtable); 563 pk = NULL; 564 if (err) { 565 char date[12]; 566 567 switch (err) { 568 case 54: 569 ve_error_set("Validation failed, certificate not valid as of %s", 570 gdate(date, sizeof(date), ve_utc)); 571 break; 572 default: 573 ve_error_set("Validation failed, err = %d", err); 574 break; 575 } 576 } else { 577 tpk = mc.vtable->get_pkey(&mc.vtable, &usages); 578 if (tpk != NULL) { 579 pk = xpkeydup(tpk); 580 } 581 } 582 VEC_CLEAR(chain); 583 return (pk); 584 } 585 586 /* 587 * Check if digest of one of the certificates from verified chain 588 * is present in the forbidden database. 589 * Since UEFI allows to store three types of digests 590 * all of them have to be checked separately. 591 */ 592 static int 593 check_forbidden_digests(br_x509_certificate *xcs, size_t num) 594 { 595 unsigned char sha256_digest[br_sha256_SIZE]; 596 unsigned char sha384_digest[br_sha384_SIZE]; 597 unsigned char sha512_digest[br_sha512_SIZE]; 598 void *tbs; 599 hash_data *digest; 600 br_hash_compat_context ctx; 601 const br_hash_class *md; 602 size_t tbs_len, i; 603 int have_sha256, have_sha384, have_sha512; 604 605 if (VEC_LEN(forbidden_digests) == 0) 606 return (0); 607 608 /* 609 * Iterate through certificates, extract their To-Be-Signed section, 610 * and compare its digest against the ones in the forbidden database. 611 */ 612 while (num--) { 613 tbs = X509_to_tbs(xcs[num].data, &tbs_len); 614 if (tbs == NULL) { 615 printf("Failed to obtain TBS part of certificate\n"); 616 return (1); 617 } 618 have_sha256 = have_sha384 = have_sha512 = 0; 619 620 for (i = 0; i < VEC_LEN(forbidden_digests); i++) { 621 digest = &VEC_ELT(forbidden_digests, i); 622 switch (digest->hash_size) { 623 case br_sha256_SIZE: 624 if (!have_sha256) { 625 have_sha256 = 1; 626 md = &br_sha256_vtable; 627 md->init(&ctx.vtable); 628 md->update(&ctx.vtable, tbs, tbs_len); 629 md->out(&ctx.vtable, sha256_digest); 630 } 631 if (!memcmp(sha256_digest, 632 digest->data, 633 br_sha256_SIZE)) 634 return (1); 635 636 break; 637 case br_sha384_SIZE: 638 if (!have_sha384) { 639 have_sha384 = 1; 640 md = &br_sha384_vtable; 641 md->init(&ctx.vtable); 642 md->update(&ctx.vtable, tbs, tbs_len); 643 md->out(&ctx.vtable, sha384_digest); 644 } 645 if (!memcmp(sha384_digest, 646 digest->data, 647 br_sha384_SIZE)) 648 return (1); 649 650 break; 651 case br_sha512_SIZE: 652 if (!have_sha512) { 653 have_sha512 = 1; 654 md = &br_sha512_vtable; 655 md->init(&ctx.vtable); 656 md->update(&ctx.vtable, tbs, tbs_len); 657 md->out(&ctx.vtable, sha512_digest); 658 } 659 if (!memcmp(sha512_digest, 660 digest->data, 661 br_sha512_SIZE)) 662 return (1); 663 664 break; 665 } 666 } 667 } 668 669 return (0); 670 } 671 672 static br_x509_pkey * 673 verify_signer(const char *certs, 674 br_name_element *elts, size_t num_elts) 675 { 676 br_x509_certificate *xcs; 677 br_x509_pkey *pk; 678 size_t num; 679 680 pk = NULL; 681 682 ve_trust_init(); 683 xcs = read_certificates(certs, &num); 684 if (xcs == NULL) { 685 ve_error_set("cannot read certificates\n"); 686 return (NULL); 687 } 688 689 /* 690 * Check if either 691 * 1. There is a direct match between cert from forbidden_anchors 692 * and a cert from chain. 693 * 2. CA that signed the chain is found in forbidden_anchors. 694 */ 695 if (VEC_LEN(forbidden_anchors) > 0) 696 pk = verify_signer_xcs(xcs, num, elts, num_elts, &forbidden_anchors); 697 if (pk != NULL) { 698 ve_error_set("Certificate is on forbidden list\n"); 699 xfreepkey(pk); 700 pk = NULL; 701 goto out; 702 } 703 704 pk = verify_signer_xcs(xcs, num, elts, num_elts, &trust_anchors); 705 if (pk == NULL) 706 goto out; 707 708 /* 709 * Check if hash of tbs part of any certificate in chain 710 * is on the forbidden list. 711 */ 712 if (check_forbidden_digests(xcs, num)) { 713 ve_error_set("Certificate hash is on forbidden list\n"); 714 xfreepkey(pk); 715 pk = NULL; 716 } 717 out: 718 free_certificates(xcs, num); 719 return (pk); 720 } 721 722 /** 723 * we need a hex digest including trailing newline below 724 */ 725 char * 726 hexdigest(char *buf, size_t bufsz, unsigned char *foo, size_t foo_len) 727 { 728 char const hex2ascii[] = "0123456789abcdef"; 729 size_t i; 730 731 /* every binary byte is 2 chars in hex + newline + null */ 732 if (bufsz < (2 * foo_len) + 2) 733 return (NULL); 734 735 for (i = 0; i < foo_len; i++) { 736 buf[i * 2] = hex2ascii[foo[i] >> 4]; 737 buf[i * 2 + 1] = hex2ascii[foo[i] & 0x0f]; 738 } 739 740 buf[i * 2] = 0x0A; /* we also want a newline */ 741 buf[i * 2 + 1] = '\0'; 742 743 return (buf); 744 } 745 746 /** 747 * @brief 748 * verify file against sigfile using pk 749 * 750 * When we generated the signature in sigfile, 751 * we hashed (sha256) file, and sent that to signing server 752 * which hashed (sha256) that hash. 753 * 754 * To verify we need to replicate that result. 755 * 756 * @param[in] pk 757 * br_x509_pkey 758 * 759 * @paramp[in] file 760 * file to be verified 761 * 762 * @param[in] sigfile 763 * signature (PEM encoded) 764 * 765 * @return NULL on error, otherwise content of file. 766 */ 767 #ifdef VE_ECDSA_SUPPORT 768 static unsigned char * 769 verify_ec(br_x509_pkey *pk, const char *file, const char *sigfile) 770 { 771 #ifdef VE_ECDSA_HASH_AGAIN 772 char *hex, hexbuf[br_sha512_SIZE * 2 + 2]; 773 #endif 774 unsigned char rhbuf[br_sha512_SIZE]; 775 br_sha256_context ctx; 776 unsigned char *fcp, *scp; 777 size_t flen, slen, plen; 778 pem_object *po; 779 const br_ec_impl *ec; 780 br_ecdsa_vrfy vrfy; 781 782 if ((fcp = read_file(file, &flen)) == NULL) 783 return (NULL); 784 if ((scp = read_file(sigfile, &slen)) == NULL) { 785 free(fcp); 786 return (NULL); 787 } 788 if ((po = decode_pem(scp, slen, &plen)) == NULL) { 789 free(fcp); 790 free(scp); 791 return (NULL); 792 } 793 br_sha256_init(&ctx); 794 br_sha256_update(&ctx, fcp, flen); 795 br_sha256_out(&ctx, rhbuf); 796 #ifdef VE_ECDSA_HASH_AGAIN 797 hex = hexdigest(hexbuf, sizeof(hexbuf), rhbuf, br_sha256_SIZE); 798 /* now hash that */ 799 if (hex) { 800 br_sha256_init(&ctx); 801 br_sha256_update(&ctx, hex, strlen(hex)); 802 br_sha256_out(&ctx, rhbuf); 803 } 804 #endif 805 ec = br_ec_get_default(); 806 vrfy = br_ecdsa_vrfy_asn1_get_default(); 807 if (!vrfy(ec, rhbuf, br_sha256_SIZE, &pk->key.ec, po->data, 808 po->data_len)) { 809 free(fcp); 810 fcp = NULL; 811 } 812 free(scp); 813 return (fcp); 814 } 815 #endif 816 817 #if defined(VE_RSA_SUPPORT) || defined(VE_OPENPGP_SUPPORT) 818 /** 819 * @brief verify an rsa digest 820 * 821 * @return 0 on failure 822 */ 823 int 824 verify_rsa_digest (br_rsa_public_key *pkey, 825 const unsigned char *hash_oid, 826 unsigned char *mdata, size_t mlen, 827 unsigned char *sdata, size_t slen) 828 { 829 br_rsa_pkcs1_vrfy vrfy; 830 unsigned char vhbuf[br_sha512_SIZE]; 831 832 vrfy = br_rsa_pkcs1_vrfy_get_default(); 833 834 if (!vrfy(sdata, slen, hash_oid, mlen, pkey, vhbuf) || 835 memcmp(vhbuf, mdata, mlen) != 0) { 836 return (0); /* fail */ 837 } 838 return (1); /* ok */ 839 } 840 #endif 841 842 /** 843 * @brief 844 * verify file against sigfile using pk 845 * 846 * When we generated the signature in sigfile, 847 * we hashed (sha256) file, and sent that to signing server 848 * which hashed (sha256) that hash. 849 * 850 * Or (deprecated) we simply used sha1 hash directly. 851 * 852 * To verify we need to replicate that result. 853 * 854 * @param[in] pk 855 * br_x509_pkey 856 * 857 * @paramp[in] file 858 * file to be verified 859 * 860 * @param[in] sigfile 861 * signature (PEM encoded) 862 * 863 * @return NULL on error, otherwise content of file. 864 */ 865 #ifdef VE_RSA_SUPPORT 866 static unsigned char * 867 verify_rsa(br_x509_pkey *pk, const char *file, const char *sigfile) 868 { 869 unsigned char rhbuf[br_sha512_SIZE]; 870 const unsigned char *hash_oid; 871 const br_hash_class *md; 872 br_hash_compat_context mctx; 873 unsigned char *fcp, *scp; 874 size_t flen, slen, plen, hlen; 875 pem_object *po; 876 877 if ((fcp = read_file(file, &flen)) == NULL) 878 return (NULL); 879 if ((scp = read_file(sigfile, &slen)) == NULL) { 880 free(fcp); 881 return (NULL); 882 } 883 if ((po = decode_pem(scp, slen, &plen)) == NULL) { 884 free(fcp); 885 free(scp); 886 return (NULL); 887 } 888 889 switch (po->data_len) { 890 #if defined(UNIT_TEST) && defined(VE_DEPRECATED_RSA_SHA1_SUPPORT) 891 case 256: 892 // this is our old deprecated sig method 893 md = &br_sha1_vtable; 894 hlen = br_sha1_SIZE; 895 hash_oid = BR_HASH_OID_SHA1; 896 break; 897 #endif 898 default: 899 md = &br_sha256_vtable; 900 hlen = br_sha256_SIZE; 901 hash_oid = BR_HASH_OID_SHA256; 902 break; 903 } 904 md->init(&mctx.vtable); 905 md->update(&mctx.vtable, fcp, flen); 906 md->out(&mctx.vtable, rhbuf); 907 if (!verify_rsa_digest(&pk->key.rsa, hash_oid, 908 rhbuf, hlen, po->data, po->data_len)) { 909 free(fcp); 910 fcp = NULL; 911 } 912 free(scp); 913 return (fcp); 914 } 915 #endif 916 917 /** 918 * @brief 919 * verify a signature and return content of signed file 920 * 921 * @param[in] sigfile 922 * file containing signature 923 * we derrive path of signed file and certificate change from 924 * this. 925 * 926 * @param[in] flags 927 * only bit 1 significant so far 928 * 929 * @return NULL on error otherwise content of signed file 930 */ 931 unsigned char * 932 verify_sig(const char *sigfile, int flags) 933 { 934 br_x509_pkey *pk; 935 br_name_element cn; 936 char cn_buf[80]; 937 unsigned char cn_oid[4]; 938 char pbuf[MAXPATHLEN]; 939 char *cp; 940 unsigned char *ucp; 941 size_t n; 942 943 DEBUG_PRINTF(5, ("verify_sig: %s\n", sigfile)); 944 n = strlcpy(pbuf, sigfile, sizeof(pbuf)); 945 if (n > (sizeof(pbuf) - 5) || strcmp(&sigfile[n - 3], "sig") != 0) 946 return (NULL); 947 cp = strcpy(&pbuf[n - 3], "certs"); 948 /* 949 * We want the commonName field 950 * the OID we want is 2,5,4,3 - but DER encoded 951 */ 952 cn_oid[0] = 3; 953 cn_oid[1] = 0x55; 954 cn_oid[2] = 4; 955 cn_oid[3] = 3; 956 cn.oid = cn_oid; 957 cn.buf = cn_buf; 958 cn.len = sizeof(cn_buf); 959 960 pk = verify_signer(pbuf, &cn, 1); 961 if (!pk) { 962 printf("cannot verify: %s: %s\n", pbuf, ve_error_get()); 963 return (NULL); 964 } 965 for (; cp > pbuf; cp--) { 966 if (*cp == '.') { 967 *cp = '\0'; 968 break; 969 } 970 } 971 switch (pk->key_type) { 972 #ifdef VE_ECDSA_SUPPORT 973 case BR_KEYTYPE_EC: 974 ucp = verify_ec(pk, pbuf, sigfile); 975 break; 976 #endif 977 #ifdef VE_RSA_SUPPORT 978 case BR_KEYTYPE_RSA: 979 ucp = verify_rsa(pk, pbuf, sigfile); 980 break; 981 #endif 982 default: 983 ucp = NULL; /* not supported */ 984 } 985 xfreepkey(pk); 986 if (!ucp) { 987 printf("Unverified %s (%s)\n", pbuf, 988 cn.status ? cn_buf : "unknown"); 989 } else if ((flags & VEF_VERBOSE) != 0) { 990 printf("Verified %s signed by %s\n", pbuf, 991 cn.status ? cn_buf : "someone we trust"); 992 } 993 return (ucp); 994 } 995 996 997 /** 998 * @brief verify hash matches 999 * 1000 * We have finished hashing a file, 1001 * see if we got the desired result. 1002 * 1003 * @param[in] ctx 1004 * pointer to hash context 1005 * 1006 * @param[in] md 1007 * pointer to hash class 1008 * 1009 * @param[in] path 1010 * name of the file we are checking 1011 * 1012 * @param[in] want 1013 * the expected result 1014 * 1015 * @param[in] hlen 1016 * size of hash output 1017 * 1018 * @return 0 on success 1019 */ 1020 int 1021 ve_check_hash(br_hash_compat_context *ctx, const br_hash_class *md, 1022 const char *path, const char *want, size_t hlen) 1023 { 1024 char hexbuf[br_sha512_SIZE * 2 + 2]; 1025 unsigned char hbuf[br_sha512_SIZE]; 1026 char *hex; 1027 int rc; 1028 int n; 1029 1030 md->out(&ctx->vtable, hbuf); 1031 #ifdef VE_PCR_SUPPORT 1032 ve_pcr_update(path, hbuf, hlen); 1033 #endif 1034 hex = hexdigest(hexbuf, sizeof(hexbuf), hbuf, hlen); 1035 if (!hex) 1036 return (VE_FINGERPRINT_WRONG); 1037 n = 2*hlen; 1038 if ((rc = strncmp(hex, want, n))) { 1039 ve_error_set("%s: %.*s != %.*s", path, n, hex, n, want); 1040 rc = VE_FINGERPRINT_WRONG; 1041 } 1042 return (rc ? rc : VE_FINGERPRINT_OK); 1043 } 1044 1045 #ifdef VE_HASH_KAT_STR 1046 static int 1047 test_hash(const br_hash_class *md, size_t hlen, 1048 const char *hname, const char *s, size_t slen, const char *want) 1049 { 1050 br_hash_compat_context mctx; 1051 1052 md->init(&mctx.vtable); 1053 md->update(&mctx.vtable, s, slen); 1054 return (ve_check_hash(&mctx, md, hname, want, hlen) != VE_FINGERPRINT_OK); 1055 } 1056 1057 #endif 1058 1059 #define ve_test_hash(n, N) \ 1060 printf("Testing hash: " #n "\t\t\t\t%s\n", \ 1061 test_hash(&br_ ## n ## _vtable, br_ ## n ## _SIZE, #n, \ 1062 VE_HASH_KAT_STR, VE_HASH_KAT_STRLEN(VE_HASH_KAT_STR), \ 1063 vh_ ## N) ? "Failed" : "Passed") 1064 1065 /** 1066 * @brief 1067 * run self tests on hash and signature verification 1068 * 1069 * Test that the hash methods (SHA1 and SHA256) work. 1070 * Test that we can verify a certificate for each supported 1071 * Root CA. 1072 * 1073 * @return cached result. 1074 */ 1075 int 1076 ve_self_tests(void) 1077 { 1078 static int once = -1; 1079 #ifdef VERIFY_CERTS_STR 1080 br_x509_certificate *xcs; 1081 br_x509_pkey *pk; 1082 br_name_element cn; 1083 char cn_buf[80]; 1084 unsigned char cn_oid[4]; 1085 size_t num; 1086 size_t u; 1087 #endif 1088 1089 if (once >= 0) 1090 return (once); 1091 once = 0; 1092 1093 DEBUG_PRINTF(5, ("Self tests...\n")); 1094 #ifdef VE_HASH_KAT_STR 1095 #ifdef VE_SHA1_SUPPORT 1096 ve_test_hash(sha1, SHA1); 1097 #endif 1098 #ifdef VE_SHA256_SUPPORT 1099 ve_test_hash(sha256, SHA256); 1100 #endif 1101 #ifdef VE_SHA384_SUPPORT 1102 ve_test_hash(sha384, SHA384); 1103 #endif 1104 #ifdef VE_SHA512_SUPPORT 1105 ve_test_hash(sha512, SHA512); 1106 #endif 1107 #endif 1108 #ifdef VERIFY_CERTS_STR 1109 xcs = parse_certificates(__DECONST(unsigned char *, VERIFY_CERTS_STR), 1110 sizeof(VERIFY_CERTS_STR), &num); 1111 if (xcs != NULL) { 1112 /* 1113 * We want the commonName field 1114 * the OID we want is 2,5,4,3 - but DER encoded 1115 */ 1116 cn_oid[0] = 3; 1117 cn_oid[1] = 0x55; 1118 cn_oid[2] = 4; 1119 cn_oid[3] = 3; 1120 cn.oid = cn_oid; 1121 cn.buf = cn_buf; 1122 1123 for (u = 0; u < num; u ++) { 1124 cn.len = sizeof(cn_buf); 1125 if ((pk = verify_signer_xcs(&xcs[u], 1, &cn, 1, &trust_anchors)) != NULL) { 1126 free_cert_contents(&xcs[u]); 1127 once++; 1128 printf("Testing verify certificate: %s\tPassed\n", 1129 cn.status ? cn_buf : ""); 1130 xfreepkey(pk); 1131 } 1132 } 1133 if (!once) 1134 printf("Testing verify certificate:\t\t\tFailed\n"); 1135 xfree(xcs); 1136 } 1137 #endif /* VERIFY_CERTS_STR */ 1138 #ifdef VE_OPENPGP_SUPPORT 1139 if (!openpgp_self_tests()) 1140 once++; 1141 #endif 1142 return (once); 1143 } 1144