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't actually care about cert status - just its name */ 245 err = mc.vtable->end_chain(&mc.vtable); 246 (void)err; /* keep compiler quiet */ 247 248 if (cn.status <= 0) 249 buf = NULL; 250 return (buf); 251 } 252 253 /* ASN parsing related defines */ 254 #define ASN1_PRIMITIVE_TAG 0x1F 255 #define ASN1_INF_LENGTH 0x80 256 #define ASN1_LENGTH_MASK 0x7F 257 258 /* 259 * Get TBS part of certificate. 260 * Since BearSSL doesn't provide any API to do this, 261 * it has to be implemented here. 262 */ 263 static void* 264 X509_to_tbs(unsigned char* cert, size_t* output_size) 265 { 266 unsigned char *result; 267 size_t tbs_size; 268 int size, i; 269 270 if (cert == NULL) 271 return (NULL); 272 273 /* Strip two sequences to get to the TBS section */ 274 for (i = 0; i < 2; i++) { 275 /* 276 * XXX: We don't need to support extended tags since 277 * they should not be present in certificates. 278 */ 279 if ((*cert & ASN1_PRIMITIVE_TAG) == ASN1_PRIMITIVE_TAG) 280 return (NULL); 281 282 cert++; 283 284 if (*cert == ASN1_INF_LENGTH) 285 return (NULL); 286 287 size = *cert & ASN1_LENGTH_MASK; 288 tbs_size = 0; 289 290 /* Size can either be stored on a single or multiple bytes */ 291 if (*cert & (ASN1_LENGTH_MASK + 1)) { 292 cert++; 293 while (*cert == 0 && size > 0) { 294 cert++; 295 size--; 296 } 297 while (size-- > 0) { 298 tbs_size <<= 8; 299 tbs_size |= *(cert++); 300 } 301 } 302 if (i == 0) 303 result = cert; 304 } 305 tbs_size += (cert - result); 306 307 if (output_size != NULL) 308 *output_size = tbs_size; 309 310 return (result); 311 } 312 313 void 314 ve_forbidden_digest_add(hash_data *digest, size_t num) 315 { 316 while (num--) 317 VEC_ADD(forbidden_digests, digest[num]); 318 } 319 320 static size_t 321 ve_anchors_add(br_x509_certificate *xcs, size_t num, anchor_list *anchors, 322 const char *anchors_name) 323 { 324 br_x509_trust_anchor ta; 325 size_t u; 326 327 for (u = 0; u < num; u++) { 328 if (certificate_to_trust_anchor_inner(&ta, &xcs[u]) < 0) { 329 break; 330 } 331 VEC_ADD(*anchors, ta); 332 if (anchor_verbose && anchors_name) { 333 char buf[64]; 334 char *cp; 335 336 cp = x509_cn_get(&xcs[u], buf, sizeof(buf)); 337 if (cp) { 338 printf("x509_anchor(%s) %s\n", cp, anchors_name); 339 } 340 } 341 } 342 return (u); 343 } 344 345 /** 346 * @brief 347 * add certs to our trust store 348 */ 349 size_t 350 ve_trust_anchors_add(br_x509_certificate *xcs, size_t num) 351 { 352 return (ve_anchors_add(xcs, num, &trust_anchors, "trusted")); 353 } 354 355 size_t 356 ve_forbidden_anchors_add(br_x509_certificate *xcs, size_t num) 357 { 358 return (ve_anchors_add(xcs, num, &forbidden_anchors, "forbidden")); 359 } 360 361 362 /** 363 * @brief add trust anchors in buf 364 * 365 * Assume buf contains x509 certificates, but if not and 366 * we support OpenPGP try adding as that. 367 * 368 * @return number of anchors added 369 */ 370 size_t 371 ve_trust_anchors_add_buf(unsigned char *buf, size_t len) 372 { 373 br_x509_certificate *xcs; 374 size_t num; 375 376 num = 0; 377 xcs = parse_certificates(buf, len, &num); 378 if (xcs != NULL) { 379 num = ve_trust_anchors_add(xcs, num); 380 #ifdef VE_OPENPGP_SUPPORT 381 } else { 382 num = openpgp_trust_add_buf(buf, len); 383 #endif 384 } 385 return (num); 386 } 387 388 /** 389 * @brief revoke trust anchors in buf 390 * 391 * Assume buf contains x509 certificates, but if not and 392 * we support OpenPGP try revoking keyId 393 * 394 * @return number of anchors revoked 395 */ 396 size_t 397 ve_trust_anchors_revoke(unsigned char *buf, size_t len) 398 { 399 br_x509_certificate *xcs; 400 size_t num; 401 402 num = 0; 403 xcs = parse_certificates(buf, len, &num); 404 if (xcs != NULL) { 405 num = ve_forbidden_anchors_add(xcs, num); 406 #ifdef VE_OPENPGP_SUPPORT 407 } else { 408 if (buf[len - 1] == '\n') 409 buf[len - 1] = '\0'; 410 num = openpgp_trust_revoke((char *)buf); 411 #endif 412 } 413 return (num); 414 } 415 416 /** 417 * @brief 418 * initialize our trust_anchors from ta_PEM 419 */ 420 int 421 ve_trust_init(void) 422 { 423 static int once = -1; 424 425 if (once >= 0) 426 return (once); 427 once = 0; /* to be sure */ 428 #ifdef BUILD_UTC 429 ve_utc_set(BUILD_UTC); /* ensure sanity */ 430 #endif 431 ve_utc_set(time(NULL)); 432 ve_error_set(NULL); /* make sure it is empty */ 433 #ifdef VE_PCR_SUPPORT 434 ve_pcr_init(); 435 #endif 436 437 #ifdef TRUST_ANCHOR_STR 438 if (TRUST_ANCHOR_STR != NULL && strlen(TRUST_ANCHOR_STR) != 0ul) 439 ve_trust_anchors_add_buf(__DECONST(unsigned char *, 440 TRUST_ANCHOR_STR), sizeof(TRUST_ANCHOR_STR)); 441 #endif 442 once = (int) VEC_LEN(trust_anchors); 443 #ifdef VE_OPENPGP_SUPPORT 444 once += openpgp_trust_init(); 445 #endif 446 return (once); 447 } 448 449 #ifdef HAVE_BR_X509_TIME_CHECK 450 static int 451 verify_time_cb(void *tctx __unused, 452 uint32_t not_before_days, uint32_t not_before_seconds, 453 uint32_t not_after_days, uint32_t not_after_seconds) 454 { 455 time_t not_before; 456 time_t not_after; 457 int rc; 458 #ifdef UNIT_TEST 459 char date[12], nb_date[12], na_date[12]; 460 #endif 461 462 if (enforce_validity) { 463 not_before = ((not_before_days - X509_DAYS_TO_UTC0) * SECONDS_PER_DAY) + not_before_seconds; 464 not_after = ((not_after_days - X509_DAYS_TO_UTC0) * SECONDS_PER_DAY) + not_after_seconds; 465 if (ve_utc < not_before) 466 rc = -1; 467 else if (ve_utc > not_after) 468 rc = 1; 469 else 470 rc = 0; 471 #ifdef UNIT_TEST 472 printf("notBefore %s notAfter %s date %s rc %d\n", 473 gdate(nb_date, sizeof(nb_date), not_before), 474 gdate(na_date, sizeof(na_date), not_after), 475 gdate(date, sizeof(date), ve_utc), rc); 476 #endif 477 } else 478 rc = 0; /* don't fail */ 479 return rc; 480 } 481 #endif 482 483 /** 484 * if we can verify the certificate chain in "certs", 485 * return the public key and if "xcp" is !NULL the associated 486 * certificate 487 */ 488 static br_x509_pkey * 489 verify_signer_xcs(br_x509_certificate *xcs, 490 size_t num, 491 br_name_element *elts, size_t num_elts, 492 anchor_list *anchors) 493 { 494 br_x509_minimal_context mc; 495 br_x509_certificate *xc; 496 size_t u; 497 cert_list chain = VEC_INIT; 498 const br_x509_pkey *tpk; 499 br_x509_pkey *pk; 500 unsigned int usages; 501 int err; 502 503 DEBUG_PRINTF(5, ("verify_signer: %zu certs in chain\n", num)); 504 VEC_ADDMANY(chain, xcs, num); 505 if (VEC_LEN(chain) == 0) { 506 ve_error_set("ERROR: no/invalid certificate chain\n"); 507 return (NULL); 508 } 509 510 DEBUG_PRINTF(5, ("verify_signer: %zu trust anchors\n", 511 VEC_LEN(*anchors))); 512 513 br_x509_minimal_init(&mc, &br_sha256_vtable, 514 &VEC_ELT(*anchors, 0), 515 VEC_LEN(*anchors)); 516 #ifdef VE_ECDSA_SUPPORT 517 br_x509_minimal_set_ecdsa(&mc, 518 &br_ec_prime_i31, &br_ecdsa_i31_vrfy_asn1); 519 #endif 520 #ifdef VE_RSA_SUPPORT 521 br_x509_minimal_set_rsa(&mc, &br_rsa_i31_pkcs1_vrfy); 522 #endif 523 #if defined(UNIT_TEST) && defined(VE_DEPRECATED_RSA_SHA1_SUPPORT) 524 /* This is deprecated! do not enable unless you absolutely have to */ 525 br_x509_minimal_set_hash(&mc, br_sha1_ID, &br_sha1_vtable); 526 #endif 527 br_x509_minimal_set_hash(&mc, br_sha256_ID, &br_sha256_vtable); 528 #ifdef VE_SHA384_SUPPORT 529 br_x509_minimal_set_hash(&mc, br_sha384_ID, &br_sha384_vtable); 530 #endif 531 #ifdef VE_SHA512_SUPPORT 532 br_x509_minimal_set_hash(&mc, br_sha512_ID, &br_sha512_vtable); 533 #endif 534 br_x509_minimal_set_name_elements(&mc, elts, num_elts); 535 536 #ifdef HAVE_BR_X509_TIME_CHECK 537 br_x509_minimal_set_time_callback(&mc, NULL, verify_time_cb); 538 #else 539 #if defined(_STANDALONE) || defined(UNIT_TEST) 540 /* 541 * Clock is probably bogus so we use ve_utc. 542 */ 543 mc.days = (ve_utc / SECONDS_PER_DAY) + X509_DAYS_TO_UTC0; 544 mc.seconds = (ve_utc % SECONDS_PER_DAY); 545 #endif 546 #endif 547 mc.vtable->start_chain(&mc.vtable, NULL); 548 for (u = 0; u < VEC_LEN(chain); u ++) { 549 xc = &VEC_ELT(chain, u); 550 mc.vtable->start_cert(&mc.vtable, xc->data_len); 551 mc.vtable->append(&mc.vtable, xc->data, xc->data_len); 552 mc.vtable->end_cert(&mc.vtable); 553 switch (mc.err) { 554 case 0: 555 case BR_ERR_X509_OK: 556 case BR_ERR_X509_EXPIRED: 557 break; 558 default: 559 printf("u=%zu mc.err=%d\n", u, mc.err); 560 break; 561 } 562 } 563 err = mc.vtable->end_chain(&mc.vtable); 564 pk = NULL; 565 if (err) { 566 char date[12]; 567 568 switch (err) { 569 case 54: 570 ve_error_set("Validation failed, certificate not valid as of %s", 571 gdate(date, sizeof(date), ve_utc)); 572 break; 573 default: 574 ve_error_set("Validation failed, err = %d", err); 575 break; 576 } 577 } else { 578 tpk = mc.vtable->get_pkey(&mc.vtable, &usages); 579 if (tpk != NULL) { 580 pk = xpkeydup(tpk); 581 } 582 } 583 VEC_CLEAR(chain); 584 return (pk); 585 } 586 587 /* 588 * Check if digest of one of the certificates from verified chain 589 * is present in the forbidden database. 590 * Since UEFI allows to store three types of digests 591 * all of them have to be checked separately. 592 */ 593 static int 594 check_forbidden_digests(br_x509_certificate *xcs, size_t num) 595 { 596 unsigned char sha256_digest[br_sha256_SIZE]; 597 unsigned char sha384_digest[br_sha384_SIZE]; 598 unsigned char sha512_digest[br_sha512_SIZE]; 599 void *tbs; 600 hash_data *digest; 601 br_hash_compat_context ctx; 602 const br_hash_class *md; 603 size_t tbs_len, i; 604 int have_sha256, have_sha384, have_sha512; 605 606 if (VEC_LEN(forbidden_digests) == 0) 607 return (0); 608 609 /* 610 * Iterate through certificates, extract their To-Be-Signed section, 611 * and compare its digest against the ones in the forbidden database. 612 */ 613 while (num--) { 614 tbs = X509_to_tbs(xcs[num].data, &tbs_len); 615 if (tbs == NULL) { 616 printf("Failed to obtain TBS part of certificate\n"); 617 return (1); 618 } 619 have_sha256 = have_sha384 = have_sha512 = 0; 620 621 for (i = 0; i < VEC_LEN(forbidden_digests); i++) { 622 digest = &VEC_ELT(forbidden_digests, i); 623 switch (digest->hash_size) { 624 case br_sha256_SIZE: 625 if (!have_sha256) { 626 have_sha256 = 1; 627 md = &br_sha256_vtable; 628 md->init(&ctx.vtable); 629 md->update(&ctx.vtable, tbs, tbs_len); 630 md->out(&ctx.vtable, sha256_digest); 631 } 632 if (!memcmp(sha256_digest, 633 digest->data, 634 br_sha256_SIZE)) 635 return (1); 636 637 break; 638 case br_sha384_SIZE: 639 if (!have_sha384) { 640 have_sha384 = 1; 641 md = &br_sha384_vtable; 642 md->init(&ctx.vtable); 643 md->update(&ctx.vtable, tbs, tbs_len); 644 md->out(&ctx.vtable, sha384_digest); 645 } 646 if (!memcmp(sha384_digest, 647 digest->data, 648 br_sha384_SIZE)) 649 return (1); 650 651 break; 652 case br_sha512_SIZE: 653 if (!have_sha512) { 654 have_sha512 = 1; 655 md = &br_sha512_vtable; 656 md->init(&ctx.vtable); 657 md->update(&ctx.vtable, tbs, tbs_len); 658 md->out(&ctx.vtable, sha512_digest); 659 } 660 if (!memcmp(sha512_digest, 661 digest->data, 662 br_sha512_SIZE)) 663 return (1); 664 665 break; 666 } 667 } 668 } 669 670 return (0); 671 } 672 673 static br_x509_pkey * 674 verify_signer(const char *certs, 675 br_name_element *elts, size_t num_elts) 676 { 677 br_x509_certificate *xcs; 678 br_x509_pkey *pk; 679 size_t num; 680 681 pk = NULL; 682 683 ve_trust_init(); 684 xcs = read_certificates(certs, &num); 685 if (xcs == NULL) { 686 ve_error_set("cannot read certificates\n"); 687 return (NULL); 688 } 689 690 /* 691 * Check if either 692 * 1. There is a direct match between cert from forbidden_anchors 693 * and a cert from chain. 694 * 2. CA that signed the chain is found in forbidden_anchors. 695 */ 696 if (VEC_LEN(forbidden_anchors) > 0) 697 pk = verify_signer_xcs(xcs, num, elts, num_elts, &forbidden_anchors); 698 if (pk != NULL) { 699 ve_error_set("Certificate is on forbidden list\n"); 700 xfreepkey(pk); 701 pk = NULL; 702 goto out; 703 } 704 705 pk = verify_signer_xcs(xcs, num, elts, num_elts, &trust_anchors); 706 if (pk == NULL) 707 goto out; 708 709 /* 710 * Check if hash of tbs part of any certificate in chain 711 * is on the forbidden list. 712 */ 713 if (check_forbidden_digests(xcs, num)) { 714 ve_error_set("Certificate hash is on forbidden list\n"); 715 xfreepkey(pk); 716 pk = NULL; 717 } 718 out: 719 free_certificates(xcs, num); 720 return (pk); 721 } 722 723 /** 724 * we need a hex digest including trailing newline below 725 */ 726 char * 727 hexdigest(char *buf, size_t bufsz, unsigned char *foo, size_t foo_len) 728 { 729 char const hex2ascii[] = "0123456789abcdef"; 730 size_t i; 731 732 /* every binary byte is 2 chars in hex + newline + null */ 733 if (bufsz < (2 * foo_len) + 2) 734 return (NULL); 735 736 for (i = 0; i < foo_len; i++) { 737 buf[i * 2] = hex2ascii[foo[i] >> 4]; 738 buf[i * 2 + 1] = hex2ascii[foo[i] & 0x0f]; 739 } 740 741 buf[i * 2] = 0x0A; /* we also want a newline */ 742 buf[i * 2 + 1] = '\0'; 743 744 return (buf); 745 } 746 747 /** 748 * @brief 749 * verify file against sigfile using pk 750 * 751 * When we generated the signature in sigfile, 752 * we hashed (sha256) file, and sent that to signing server 753 * which hashed (sha256) that hash. 754 * 755 * To verify we need to replicate that result. 756 * 757 * @param[in] pk 758 * br_x509_pkey 759 * 760 * @paramp[in] file 761 * file to be verified 762 * 763 * @param[in] sigfile 764 * signature (PEM encoded) 765 * 766 * @return NULL on error, otherwise content of file. 767 */ 768 #ifdef VE_ECDSA_SUPPORT 769 static unsigned char * 770 verify_ec(br_x509_pkey *pk, const char *file, const char *sigfile) 771 { 772 #ifdef VE_ECDSA_HASH_AGAIN 773 char *hex, hexbuf[br_sha512_SIZE * 2 + 2]; 774 #endif 775 unsigned char rhbuf[br_sha512_SIZE]; 776 br_sha256_context ctx; 777 unsigned char *fcp, *scp; 778 size_t flen, slen, plen; 779 pem_object *po; 780 const br_ec_impl *ec; 781 br_ecdsa_vrfy vrfy; 782 783 if ((fcp = read_file(file, &flen)) == NULL) 784 return (NULL); 785 if ((scp = read_file(sigfile, &slen)) == NULL) { 786 free(fcp); 787 return (NULL); 788 } 789 if ((po = decode_pem(scp, slen, &plen)) == NULL) { 790 free(fcp); 791 free(scp); 792 return (NULL); 793 } 794 br_sha256_init(&ctx); 795 br_sha256_update(&ctx, fcp, flen); 796 br_sha256_out(&ctx, rhbuf); 797 #ifdef VE_ECDSA_HASH_AGAIN 798 hex = hexdigest(hexbuf, sizeof(hexbuf), rhbuf, br_sha256_SIZE); 799 /* now hash that */ 800 if (hex) { 801 br_sha256_init(&ctx); 802 br_sha256_update(&ctx, hex, strlen(hex)); 803 br_sha256_out(&ctx, rhbuf); 804 } 805 #endif 806 ec = br_ec_get_default(); 807 vrfy = br_ecdsa_vrfy_asn1_get_default(); 808 if (!vrfy(ec, rhbuf, br_sha256_SIZE, &pk->key.ec, po->data, 809 po->data_len)) { 810 free(fcp); 811 fcp = NULL; 812 } 813 free(scp); 814 return (fcp); 815 } 816 #endif 817 818 #if defined(VE_RSA_SUPPORT) || defined(VE_OPENPGP_SUPPORT) 819 /** 820 * @brief verify an rsa digest 821 * 822 * @return 0 on failure 823 */ 824 int 825 verify_rsa_digest (br_rsa_public_key *pkey, 826 const unsigned char *hash_oid, 827 unsigned char *mdata, size_t mlen, 828 unsigned char *sdata, size_t slen) 829 { 830 br_rsa_pkcs1_vrfy vrfy; 831 unsigned char vhbuf[br_sha512_SIZE]; 832 833 vrfy = br_rsa_pkcs1_vrfy_get_default(); 834 835 if (!vrfy(sdata, slen, hash_oid, mlen, pkey, vhbuf) || 836 memcmp(vhbuf, mdata, mlen) != 0) { 837 return (0); /* fail */ 838 } 839 return (1); /* ok */ 840 } 841 #endif 842 843 /** 844 * @brief 845 * verify file against sigfile using pk 846 * 847 * When we generated the signature in sigfile, 848 * we hashed (sha256) file, and sent that to signing server 849 * which hashed (sha256) that hash. 850 * 851 * Or (deprecated) we simply used sha1 hash directly. 852 * 853 * To verify we need to replicate that result. 854 * 855 * @param[in] pk 856 * br_x509_pkey 857 * 858 * @paramp[in] file 859 * file to be verified 860 * 861 * @param[in] sigfile 862 * signature (PEM encoded) 863 * 864 * @return NULL on error, otherwise content of file. 865 */ 866 #ifdef VE_RSA_SUPPORT 867 static unsigned char * 868 verify_rsa(br_x509_pkey *pk, const char *file, const char *sigfile) 869 { 870 unsigned char rhbuf[br_sha512_SIZE]; 871 const unsigned char *hash_oid; 872 const br_hash_class *md; 873 br_hash_compat_context mctx; 874 unsigned char *fcp, *scp; 875 size_t flen, slen, plen, hlen; 876 pem_object *po; 877 878 if ((fcp = read_file(file, &flen)) == NULL) 879 return (NULL); 880 if ((scp = read_file(sigfile, &slen)) == NULL) { 881 free(fcp); 882 return (NULL); 883 } 884 if ((po = decode_pem(scp, slen, &plen)) == NULL) { 885 free(fcp); 886 free(scp); 887 return (NULL); 888 } 889 890 switch (po->data_len) { 891 #if defined(UNIT_TEST) && defined(VE_DEPRECATED_RSA_SHA1_SUPPORT) 892 case 256: 893 // this is our old deprecated sig method 894 md = &br_sha1_vtable; 895 hlen = br_sha1_SIZE; 896 hash_oid = BR_HASH_OID_SHA1; 897 break; 898 #endif 899 default: 900 md = &br_sha256_vtable; 901 hlen = br_sha256_SIZE; 902 hash_oid = BR_HASH_OID_SHA256; 903 break; 904 } 905 md->init(&mctx.vtable); 906 md->update(&mctx.vtable, fcp, flen); 907 md->out(&mctx.vtable, rhbuf); 908 if (!verify_rsa_digest(&pk->key.rsa, hash_oid, 909 rhbuf, hlen, po->data, po->data_len)) { 910 free(fcp); 911 fcp = NULL; 912 } 913 free(scp); 914 return (fcp); 915 } 916 #endif 917 918 /** 919 * @brief 920 * verify a signature and return content of signed file 921 * 922 * @param[in] sigfile 923 * file containing signature 924 * we derrive path of signed file and certificate change from 925 * this. 926 * 927 * @param[in] flags 928 * only bit 1 significant so far 929 * 930 * @return NULL on error otherwise content of signed file 931 */ 932 unsigned char * 933 verify_sig(const char *sigfile, int flags) 934 { 935 br_x509_pkey *pk; 936 br_name_element cn; 937 char cn_buf[80]; 938 unsigned char cn_oid[4]; 939 char pbuf[MAXPATHLEN]; 940 char *cp; 941 unsigned char *ucp; 942 size_t n; 943 944 DEBUG_PRINTF(5, ("verify_sig: %s\n", sigfile)); 945 n = strlcpy(pbuf, sigfile, sizeof(pbuf)); 946 if (n > (sizeof(pbuf) - 5) || strcmp(&sigfile[n - 3], "sig") != 0) 947 return (NULL); 948 cp = strcpy(&pbuf[n - 3], "certs"); 949 /* 950 * We want the commonName field 951 * the OID we want is 2,5,4,3 - but DER encoded 952 */ 953 cn_oid[0] = 3; 954 cn_oid[1] = 0x55; 955 cn_oid[2] = 4; 956 cn_oid[3] = 3; 957 cn.oid = cn_oid; 958 cn.buf = cn_buf; 959 cn.len = sizeof(cn_buf); 960 961 pk = verify_signer(pbuf, &cn, 1); 962 if (!pk) { 963 printf("cannot verify: %s: %s\n", pbuf, ve_error_get()); 964 return (NULL); 965 } 966 for (; cp > pbuf; cp--) { 967 if (*cp == '.') { 968 *cp = '\0'; 969 break; 970 } 971 } 972 switch (pk->key_type) { 973 #ifdef VE_ECDSA_SUPPORT 974 case BR_KEYTYPE_EC: 975 ucp = verify_ec(pk, pbuf, sigfile); 976 break; 977 #endif 978 #ifdef VE_RSA_SUPPORT 979 case BR_KEYTYPE_RSA: 980 ucp = verify_rsa(pk, pbuf, sigfile); 981 break; 982 #endif 983 default: 984 ucp = NULL; /* not supported */ 985 } 986 xfreepkey(pk); 987 if (!ucp) { 988 printf("Unverified %s (%s)\n", pbuf, 989 cn.status ? cn_buf : "unknown"); 990 } else if ((flags & VEF_VERBOSE) != 0) { 991 printf("Verified %s signed by %s\n", pbuf, 992 cn.status ? cn_buf : "someone we trust"); 993 } 994 return (ucp); 995 } 996 997 998 /** 999 * @brief verify hash matches 1000 * 1001 * We have finished hashing a file, 1002 * see if we got the desired result. 1003 * 1004 * @param[in] ctx 1005 * pointer to hash context 1006 * 1007 * @param[in] md 1008 * pointer to hash class 1009 * 1010 * @param[in] path 1011 * name of the file we are checking 1012 * 1013 * @param[in] want 1014 * the expected result 1015 * 1016 * @param[in] hlen 1017 * size of hash output 1018 * 1019 * @return 0 on success 1020 */ 1021 int 1022 ve_check_hash(br_hash_compat_context *ctx, const br_hash_class *md, 1023 const char *path, const char *want, size_t hlen) 1024 { 1025 char hexbuf[br_sha512_SIZE * 2 + 2]; 1026 unsigned char hbuf[br_sha512_SIZE]; 1027 char *hex; 1028 int rc; 1029 int n; 1030 1031 md->out(&ctx->vtable, hbuf); 1032 #ifdef VE_PCR_SUPPORT 1033 ve_pcr_update(path, hbuf, hlen); 1034 #endif 1035 hex = hexdigest(hexbuf, sizeof(hexbuf), hbuf, hlen); 1036 if (!hex) 1037 return (VE_FINGERPRINT_WRONG); 1038 n = 2*hlen; 1039 if ((rc = strncmp(hex, want, n))) { 1040 ve_error_set("%s: %.*s != %.*s", path, n, hex, n, want); 1041 rc = VE_FINGERPRINT_WRONG; 1042 } 1043 return (rc ? rc : VE_FINGERPRINT_OK); 1044 } 1045 1046 #ifdef VE_HASH_KAT_STR 1047 static int 1048 test_hash(const br_hash_class *md, size_t hlen, 1049 const char *hname, const char *s, size_t slen, const char *want) 1050 { 1051 br_hash_compat_context mctx; 1052 1053 md->init(&mctx.vtable); 1054 md->update(&mctx.vtable, s, slen); 1055 return (ve_check_hash(&mctx, md, hname, want, hlen) != VE_FINGERPRINT_OK); 1056 } 1057 1058 #endif 1059 1060 #define ve_test_hash(n, N) \ 1061 printf("Testing hash: " #n "\t\t\t\t%s\n", \ 1062 test_hash(&br_ ## n ## _vtable, br_ ## n ## _SIZE, #n, \ 1063 VE_HASH_KAT_STR, VE_HASH_KAT_STRLEN(VE_HASH_KAT_STR), \ 1064 vh_ ## N) ? "Failed" : "Passed") 1065 1066 /** 1067 * @brief 1068 * run self tests on hash and signature verification 1069 * 1070 * Test that the hash methods (SHA1 and SHA256) work. 1071 * Test that we can verify a certificate for each supported 1072 * Root CA. 1073 * 1074 * @return cached result. 1075 */ 1076 int 1077 ve_self_tests(void) 1078 { 1079 static int once = -1; 1080 #ifdef VERIFY_CERTS_STR 1081 br_x509_certificate *xcs; 1082 br_x509_pkey *pk; 1083 br_name_element cn; 1084 char cn_buf[80]; 1085 unsigned char cn_oid[4]; 1086 size_t num; 1087 size_t u; 1088 #endif 1089 1090 if (once >= 0) 1091 return (once); 1092 once = 0; 1093 1094 DEBUG_PRINTF(5, ("Self tests...\n")); 1095 #ifdef VE_HASH_KAT_STR 1096 #ifdef VE_SHA1_SUPPORT 1097 ve_test_hash(sha1, SHA1); 1098 #endif 1099 #ifdef VE_SHA256_SUPPORT 1100 ve_test_hash(sha256, SHA256); 1101 #endif 1102 #ifdef VE_SHA384_SUPPORT 1103 ve_test_hash(sha384, SHA384); 1104 #endif 1105 #ifdef VE_SHA512_SUPPORT 1106 ve_test_hash(sha512, SHA512); 1107 #endif 1108 #endif 1109 #ifdef VERIFY_CERTS_STR 1110 xcs = parse_certificates(__DECONST(unsigned char *, VERIFY_CERTS_STR), 1111 sizeof(VERIFY_CERTS_STR), &num); 1112 if (xcs != NULL) { 1113 /* 1114 * We want the commonName field 1115 * the OID we want is 2,5,4,3 - but DER encoded 1116 */ 1117 cn_oid[0] = 3; 1118 cn_oid[1] = 0x55; 1119 cn_oid[2] = 4; 1120 cn_oid[3] = 3; 1121 cn.oid = cn_oid; 1122 cn.buf = cn_buf; 1123 1124 for (u = 0; u < num; u ++) { 1125 cn.len = sizeof(cn_buf); 1126 if ((pk = verify_signer_xcs(&xcs[u], 1, &cn, 1, &trust_anchors)) != NULL) { 1127 free_cert_contents(&xcs[u]); 1128 once++; 1129 printf("Testing verify certificate: %s\tPassed\n", 1130 cn.status ? cn_buf : ""); 1131 xfreepkey(pk); 1132 } 1133 } 1134 if (!once) 1135 printf("Testing verify certificate:\t\t\tFailed\n"); 1136 xfree(xcs); 1137 } 1138 #endif /* VERIFY_CERTS_STR */ 1139 #ifdef VE_OPENPGP_SUPPORT 1140 if (!openpgp_self_tests()) 1141 once++; 1142 #endif 1143 return (once); 1144 } 1145