1 /* $OpenBSD: x509_constraints.c,v 1.26 2022/03/26 16:34:21 tb Exp $ */ 2 /* 3 * Copyright (c) 2020 Bob Beck <beck@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include <ctype.h> 19 #include <errno.h> 20 #include <stdio.h> 21 #include <string.h> 22 #include <time.h> 23 #include <unistd.h> 24 25 #include <sys/socket.h> 26 #include <arpa/inet.h> 27 28 #include <openssl/safestack.h> 29 #include <openssl/x509.h> 30 #include <openssl/x509v3.h> 31 32 #include "x509_internal.h" 33 34 /* RFC 2821 section 4.5.3.1 */ 35 #define LOCAL_PART_MAX_LEN 64 36 #define DOMAIN_PART_MAX_LEN 255 37 38 struct x509_constraints_name * 39 x509_constraints_name_new(void) 40 { 41 return (calloc(1, sizeof(struct x509_constraints_name))); 42 } 43 44 void 45 x509_constraints_name_clear(struct x509_constraints_name *name) 46 { 47 free(name->name); 48 free(name->local); 49 free(name->der); 50 memset(name, 0, sizeof(*name)); 51 } 52 53 void 54 x509_constraints_name_free(struct x509_constraints_name *name) 55 { 56 if (name == NULL) 57 return; 58 x509_constraints_name_clear(name); 59 free(name); 60 } 61 62 struct x509_constraints_name * 63 x509_constraints_name_dup(struct x509_constraints_name *name) 64 { 65 struct x509_constraints_name *new; 66 67 if ((new = x509_constraints_name_new()) == NULL) 68 goto err; 69 new->type = name->type; 70 new->af = name->af; 71 new->der_len = name->der_len; 72 if (name->der_len > 0) { 73 if ((new->der = malloc(name->der_len)) == NULL) 74 goto err; 75 memcpy(new->der, name->der, name->der_len); 76 } 77 if (name->name != NULL && (new->name = strdup(name->name)) == NULL) 78 goto err; 79 if (name->local != NULL && (new->local = strdup(name->local)) == NULL) 80 goto err; 81 memcpy(new->address, name->address, sizeof(name->address)); 82 return new; 83 err: 84 x509_constraints_name_free(new); 85 return NULL; 86 } 87 88 struct x509_constraints_names * 89 x509_constraints_names_new(size_t names_max) 90 { 91 struct x509_constraints_names *new; 92 93 if ((new = calloc(1, sizeof(struct x509_constraints_names))) == NULL) 94 return NULL; 95 96 new->names_max = names_max; 97 98 return new; 99 } 100 101 void 102 x509_constraints_names_clear(struct x509_constraints_names *names) 103 { 104 size_t i; 105 106 for (i = 0; i < names->names_count; i++) 107 x509_constraints_name_free(names->names[i]); 108 free(names->names); 109 memset(names, 0, sizeof(*names)); 110 } 111 112 void 113 x509_constraints_names_free(struct x509_constraints_names *names) 114 { 115 if (names == NULL) 116 return; 117 118 x509_constraints_names_clear(names); 119 free(names); 120 } 121 122 int 123 x509_constraints_names_add(struct x509_constraints_names *names, 124 struct x509_constraints_name *name) 125 { 126 if (names->names_count >= names->names_max) 127 return 0; 128 if (names->names_count == names->names_len) { 129 struct x509_constraints_name **tmp; 130 if ((tmp = recallocarray(names->names, names->names_len, 131 names->names_len + 32, sizeof(*tmp))) == NULL) 132 return 0; 133 names->names_len += 32; 134 names->names = tmp; 135 } 136 names->names[names->names_count] = name; 137 names->names_count++; 138 return 1; 139 } 140 141 struct x509_constraints_names * 142 x509_constraints_names_dup(struct x509_constraints_names *names) 143 { 144 struct x509_constraints_names *new = NULL; 145 struct x509_constraints_name *name = NULL; 146 size_t i; 147 148 if (names == NULL) 149 return NULL; 150 151 if ((new = x509_constraints_names_new(names->names_max)) == NULL) 152 goto err; 153 154 for (i = 0; i < names->names_count; i++) { 155 if ((name = x509_constraints_name_dup(names->names[i])) == NULL) 156 goto err; 157 if (!x509_constraints_names_add(new, name)) 158 goto err; 159 } 160 161 return new; 162 err: 163 x509_constraints_names_free(new); 164 x509_constraints_name_free(name); 165 return NULL; 166 } 167 168 169 /* 170 * Validate that the name contains only a hostname consisting of RFC 171 * 5890 compliant A-labels (see RFC 6066 section 3). This is more 172 * permissive to allow for a leading '.' for a subdomain based 173 * constraint, as well as allowing for '_' which is commonly accepted 174 * by nonconformant DNS implementaitons. 175 * 176 * if "wildcards" is set it allows '*' to occur in the string at the end of a 177 * component. 178 */ 179 static int 180 x509_constraints_valid_domain_internal(uint8_t *name, size_t len, int wildcards) 181 { 182 uint8_t prev, c = 0; 183 int component = 0; 184 int first; 185 size_t i; 186 187 if (len > DOMAIN_PART_MAX_LEN) 188 return 0; 189 190 for (i = 0; i < len; i++) { 191 prev = c; 192 c = name[i]; 193 194 first = (i == 0); 195 196 /* Everything has to be ASCII, with no NUL byte */ 197 if (!isascii(c) || c == '\0') 198 return 0; 199 /* It must be alphanumeric, a '-', '.', '_' or '*' */ 200 if (!isalnum(c) && c != '-' && c != '.' && c != '_' && c != '*') 201 return 0; 202 203 /* if it is a '*', fail if not wildcards */ 204 if (!wildcards && c == '*') 205 return 0; 206 207 /* '-' must not start a component or be at the end. */ 208 if (c == '-' && (component == 0 || i == len - 1)) 209 return 0; 210 211 /* 212 * '.' must not be at the end. It may be first overall 213 * but must not otherwise start a component. 214 */ 215 if (c == '.' && ((component == 0 && !first) || i == len - 1)) 216 return 0; 217 218 if (c == '.') { 219 /* Components can not end with a dash. */ 220 if (prev == '-') 221 return 0; 222 /* Start new component */ 223 component = 0; 224 continue; 225 } 226 /* 227 * Wildcards can only occur at the end of a component. 228 * c*.com is valid, c*c.com is not. 229 */ 230 if (prev == '*') 231 return 0; 232 233 /* Components must be 63 chars or less. */ 234 if (++component > 63) 235 return 0; 236 } 237 return 1; 238 } 239 240 int 241 x509_constraints_valid_domain(uint8_t *name, size_t len) 242 { 243 if (len == 0) 244 return 0; 245 /* 246 * A domain may not be less than two characters, so you can't 247 * have a require subdomain name with less than that. 248 */ 249 if (len < 3 && name[0] == '.') 250 return 0; 251 return x509_constraints_valid_domain_internal(name, len, 0); 252 } 253 254 int 255 x509_constraints_valid_host(uint8_t *name, size_t len) 256 { 257 struct sockaddr_in sin4; 258 struct sockaddr_in6 sin6; 259 260 if (len == 0) 261 return 0; 262 if (name[0] == '.') /* leading . not allowed in a host name*/ 263 return 0; 264 if (inet_pton(AF_INET, name, &sin4) == 1) 265 return 0; 266 if (inet_pton(AF_INET6, name, &sin6) == 1) 267 return 0; 268 return x509_constraints_valid_domain_internal(name, len, 0); 269 } 270 271 int 272 x509_constraints_valid_sandns(uint8_t *name, size_t len) 273 { 274 if (len == 0) 275 return 0; 276 277 if (name[0] == '.') /* leading . not allowed in a SAN DNS name */ 278 return 0; 279 /* 280 * A domain may not be less than two characters, so you 281 * can't wildcard a single domain of less than that 282 */ 283 if (len < 4 && name[0] == '*') 284 return 0; 285 /* 286 * A wildcard may only be followed by a '.' 287 */ 288 if (len >= 4 && name[0] == '*' && name[1] != '.') 289 return 0; 290 291 return x509_constraints_valid_domain_internal(name, len, 1); 292 } 293 294 static inline int 295 local_part_ok(char c) 296 { 297 return (('0' <= c && c <= '9') || ('a' <= c && c <= 'z') || 298 ('A' <= c && c <= 'Z') || c == '!' || c == '#' || c == '$' || 299 c == '%' || c == '&' || c == '\'' || c == '*' || c == '+' || 300 c == '-' || c == '/' || c == '=' || c == '?' || c == '^' || 301 c == '_' || c == '`' || c == '{' || c == '|' || c == '}' || 302 c == '~' || c == '.'); 303 } 304 305 /* 306 * Parse "candidate" as an RFC 2821 mailbox. 307 * Returns 0 if candidate is not a valid mailbox or if an error occurs. 308 * Returns 1 if candidate is a mailbox and adds newly allocated 309 * local and domain parts of the mailbox to "name->local" and name->name" 310 */ 311 int 312 x509_constraints_parse_mailbox(uint8_t *candidate, size_t len, 313 struct x509_constraints_name *name) 314 { 315 char working[DOMAIN_PART_MAX_LEN + 1] = { 0 }; 316 char *candidate_local = NULL; 317 char *candidate_domain = NULL; 318 size_t i, wi = 0; 319 int accept = 0; 320 int quoted = 0; 321 322 if (candidate == NULL) 323 return 0; 324 325 /* It can't be bigger than the local part, domain part and the '@' */ 326 if (len > LOCAL_PART_MAX_LEN + DOMAIN_PART_MAX_LEN + 1) 327 return 0; 328 329 for (i = 0; i < len; i++) { 330 char c = candidate[i]; 331 /* non ascii, cr, lf, or nul is never allowed */ 332 if (!isascii(c) || c == '\r' || c == '\n' || c == '\0') 333 goto bad; 334 if (i == 0) { 335 /* local part is quoted part */ 336 if (c == '"') 337 quoted = 1; 338 /* can not start with a . */ 339 if (c == '.') 340 goto bad; 341 } 342 if (accept) { 343 if (wi >= DOMAIN_PART_MAX_LEN) 344 goto bad; 345 working[wi++] = c; 346 accept = 0; 347 continue; 348 } 349 if (candidate_local != NULL) { 350 /* We are looking for the domain part */ 351 if (wi >= DOMAIN_PART_MAX_LEN) 352 goto bad; 353 working[wi++] = c; 354 if (i == len - 1) { 355 if (wi == 0) 356 goto bad; 357 if (candidate_domain != NULL) 358 goto bad; 359 candidate_domain = strdup(working); 360 if (candidate_domain == NULL) 361 goto bad; 362 } 363 continue; 364 } 365 /* We are looking for the local part */ 366 if (wi >= LOCAL_PART_MAX_LEN) 367 break; 368 369 if (quoted) { 370 if (c == '\\') { 371 accept = 1; 372 continue; 373 } 374 if (c == '"' && i != 0) { 375 /* end the quoted part. @ must be next */ 376 if (i + 1 == len || candidate[i + 1] != '@') 377 goto bad; 378 quoted = 0; 379 } 380 /* 381 * XXX Go strangely permits sp but forbids ht 382 * mimic that for now 383 */ 384 if (c == 9) 385 goto bad; 386 if (wi >= LOCAL_PART_MAX_LEN) 387 goto bad; 388 working[wi++] = c; 389 continue; /* all's good inside our quoted string */ 390 } 391 if (c == '@') { 392 if (wi == 0) 393 goto bad; 394 if (candidate_local != NULL) 395 goto bad; 396 candidate_local = strdup(working); 397 if (candidate_local == NULL) 398 goto bad; 399 memset(working, 0, sizeof(working)); 400 wi = 0; 401 continue; 402 } 403 if (c == '\\') { 404 /* 405 * RFC 3936 hints these can happen outside of 406 * quotend string. don't include the \ but 407 * next character must be ok. 408 */ 409 if (i + 1 == len) 410 goto bad; 411 if (!local_part_ok(candidate[i + 1])) 412 goto bad; 413 accept = 1; 414 } 415 if (!local_part_ok(c)) 416 goto bad; 417 if (wi >= LOCAL_PART_MAX_LEN) 418 goto bad; 419 working[wi++] = c; 420 } 421 if (candidate_local == NULL || candidate_domain == NULL) 422 goto bad; 423 if (!x509_constraints_valid_host(candidate_domain, 424 strlen(candidate_domain))) 425 goto bad; 426 427 if (name != NULL) { 428 name->local = candidate_local; 429 name->name = candidate_domain; 430 name->type = GEN_EMAIL; 431 } else { 432 free(candidate_local); 433 free(candidate_domain); 434 } 435 return 1; 436 bad: 437 free(candidate_local); 438 free(candidate_domain); 439 return 0; 440 } 441 442 int 443 x509_constraints_valid_domain_constraint(uint8_t *constraint, size_t len) 444 { 445 if (len == 0) 446 return 1; /* empty constraints match */ 447 448 /* 449 * A domain may not be less than two characters, so you 450 * can't match a single domain of less than that 451 */ 452 if (len < 3 && constraint[0] == '.') 453 return 0; 454 return x509_constraints_valid_domain_internal(constraint, len, 0); 455 } 456 457 /* 458 * Extract the host part of a URI, returns the host part as a c string 459 * the caller must free, or or NULL if it could not be found or is 460 * invalid. 461 * 462 * RFC 3986: 463 * the authority part of a uri starts with // and is terminated with 464 * the next '/', '?', '#' or end of the URI. 465 * 466 * The authority itself contains [userinfo '@'] host [: port] 467 * 468 * so the host starts at the start or after the '@', and ends 469 * with end of URI, '/', '?', "#', or ':'. 470 */ 471 int 472 x509_constraints_uri_host(uint8_t *uri, size_t len, char **hostpart) 473 { 474 size_t i, hostlen = 0; 475 uint8_t *authority = NULL; 476 char *host = NULL; 477 478 /* 479 * Find first '//'. there must be at least a '//' and 480 * something else. 481 */ 482 if (len < 3) 483 return 0; 484 for (i = 0; i < len - 1; i++) { 485 if (!isascii(uri[i])) 486 return 0; 487 if (uri[i] == '/' && uri[i + 1] == '/') { 488 authority = uri + i + 2; 489 break; 490 } 491 } 492 if (authority == NULL) 493 return 0; 494 for (i = authority - uri; i < len; i++) { 495 if (!isascii(uri[i])) 496 return 0; 497 /* it has a userinfo part */ 498 if (uri[i] == '@') { 499 hostlen = 0; 500 /* it can only have one */ 501 if (host != NULL) 502 break; 503 /* start after the userinfo part */ 504 host = uri + i + 1; 505 continue; 506 } 507 /* did we find the end? */ 508 if (uri[i] == ':' || uri[i] == '/' || uri[i] == '?' || 509 uri[i] == '#') 510 break; 511 hostlen++; 512 } 513 if (hostlen == 0) 514 return 0; 515 if (host == NULL) 516 host = authority; 517 if (!x509_constraints_valid_host(host, hostlen)) 518 return 0; 519 if (hostpart != NULL) 520 *hostpart = strndup(host, hostlen); 521 return 1; 522 } 523 524 int 525 x509_constraints_sandns(char *sandns, size_t dlen, char *constraint, size_t len) 526 { 527 char *suffix; 528 529 if (len == 0) 530 return 1; /* an empty constraint matches everything */ 531 532 /* match the end of the domain */ 533 if (dlen < len) 534 return 0; 535 suffix = sandns + (dlen - len); 536 return (strncasecmp(suffix, constraint, len) == 0); 537 } 538 539 /* 540 * Validate a pre-validated domain of length dlen against a pre-validated 541 * constraint of length len. 542 * 543 * returns 1 if the domain and constraint match. 544 * returns 0 otherwise. 545 * 546 * an empty constraint matches everyting. 547 * constraint will be matched against the domain as a suffix if it 548 * starts with a '.'. 549 * domain will be matched against the constraint as a suffix if it 550 * starts with a '.'. 551 */ 552 int 553 x509_constraints_domain(char *domain, size_t dlen, char *constraint, size_t len) 554 { 555 if (len == 0) 556 return 1; /* an empty constraint matches everything */ 557 558 if (constraint[0] == '.') { 559 /* match the end of the domain */ 560 char *suffix; 561 if (dlen < len) 562 return 0; 563 suffix = domain + (dlen - len); 564 return (strncasecmp(suffix, constraint, len) == 0); 565 } 566 if (domain[0] == '.') { 567 /* match the end of the constraint */ 568 char *suffix; 569 if (len < dlen) 570 return 0; 571 suffix = constraint + (len - dlen); 572 return (strncasecmp(suffix, domain, dlen) == 0); 573 } 574 /* otherwise we must exactly match the constraint */ 575 if (dlen != len) 576 return 0; 577 return (strncasecmp(domain, constraint, len) == 0); 578 } 579 580 int 581 x509_constraints_uri(uint8_t *uri, size_t ulen, uint8_t *constraint, size_t len, 582 int *error) 583 { 584 int ret = 0; 585 char *hostpart = NULL; 586 587 if (!x509_constraints_uri_host(uri, ulen, &hostpart)) { 588 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 589 goto err; 590 } 591 if (hostpart == NULL) { 592 *error = X509_V_ERR_OUT_OF_MEM; 593 goto err; 594 } 595 if (!x509_constraints_valid_domain_constraint(constraint, len)) { 596 *error = X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX; 597 goto err; 598 } 599 ret = x509_constraints_domain(hostpart, strlen(hostpart), constraint, 600 len); 601 err: 602 free(hostpart); 603 return ret; 604 } 605 606 /* 607 * Verify a validated address of size alen with a validated contraint 608 * of size constraint_len. returns 1 if matching, 0 if not. 609 * Addresses are assumed to be pre-validated for a length of 4 and 8 610 * respectively for ipv4 addreses and constraints, and a length of 611 * 16 and 32 respectively for ipv6 address constraints by the caller. 612 */ 613 int 614 x509_constraints_ipaddr(uint8_t *address, size_t alen, uint8_t *constraint, 615 size_t len) 616 { 617 uint8_t *mask; 618 size_t i; 619 620 if (alen * 2 != len) 621 return 0; 622 623 mask = constraint + alen; 624 for (i = 0; i < alen; i++) { 625 if ((address[i] & mask[i]) != (constraint[i] & mask[i])) 626 return 0; 627 } 628 return 1; 629 } 630 631 /* 632 * Verify a canonicalized der encoded constraint dirname 633 * a canonicalized der encoded constraint. 634 */ 635 int 636 x509_constraints_dirname(uint8_t *dirname, size_t dlen, 637 uint8_t *constraint, size_t len) 638 { 639 /* 640 * The constraint must be a prefix in DER format, so it can't be 641 * longer than the name it is checked against. 642 */ 643 if (len > dlen) 644 return 0; 645 return (memcmp(constraint, dirname, len) == 0); 646 } 647 648 /* 649 * De-obfuscate a GENERAL_NAME into useful bytes for a name or constraint. 650 */ 651 int 652 x509_constraints_general_to_bytes(GENERAL_NAME *name, uint8_t **bytes, 653 size_t *len) 654 { 655 *bytes = NULL; 656 *len = 0; 657 658 if (name->type == GEN_DNS) { 659 ASN1_IA5STRING *aname = name->d.dNSName; 660 661 *bytes = aname->data; 662 *len = aname->length; 663 664 return name->type; 665 } 666 if (name->type == GEN_EMAIL) { 667 ASN1_IA5STRING *aname = name->d.rfc822Name; 668 669 *bytes = aname->data; 670 *len = aname->length; 671 672 return name->type; 673 } 674 if (name->type == GEN_URI) { 675 ASN1_IA5STRING *aname = name->d.uniformResourceIdentifier; 676 677 *bytes = aname->data; 678 *len = aname->length; 679 680 return name->type; 681 } 682 if (name->type == GEN_DIRNAME) { 683 X509_NAME *dname = name->d.directoryName; 684 685 if (!dname->modified || i2d_X509_NAME(dname, NULL) >= 0) { 686 *bytes = dname->canon_enc; 687 *len = dname->canon_enclen; 688 689 return name->type; 690 } 691 } 692 if (name->type == GEN_IPADD) { 693 *bytes = name->d.ip->data; 694 *len = name->d.ip->length; 695 696 return name->type; 697 } 698 699 return 0; 700 } 701 702 703 /* 704 * Extract the relevant names for constraint checking from "cert", 705 * validate them, and add them to the list of cert names for "chain". 706 * returns 1 on success sets error and returns 0 on failure. 707 */ 708 int 709 x509_constraints_extract_names(struct x509_constraints_names *names, 710 X509 *cert, int is_leaf, int *error) 711 { 712 struct x509_constraints_name *vname = NULL; 713 X509_NAME *subject_name; 714 GENERAL_NAME *name; 715 ssize_t i = 0; 716 int name_type, include_cn = is_leaf, include_email = is_leaf; 717 718 /* first grab the altnames */ 719 while ((name = sk_GENERAL_NAME_value(cert->altname, i++)) != NULL) { 720 uint8_t *bytes = NULL; 721 size_t len = 0; 722 723 if ((vname = x509_constraints_name_new()) == NULL) { 724 *error = X509_V_ERR_OUT_OF_MEM; 725 goto err; 726 } 727 728 name_type = x509_constraints_general_to_bytes(name, &bytes, 729 &len); 730 switch(name_type) { 731 case GEN_DNS: 732 if (!x509_constraints_valid_sandns(bytes, len)) { 733 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 734 goto err; 735 } 736 if ((vname->name = strndup(bytes, len)) == NULL) { 737 *error = X509_V_ERR_OUT_OF_MEM; 738 goto err; 739 } 740 vname->type = GEN_DNS; 741 include_cn = 0; /* don't use cn from subject */ 742 break; 743 case GEN_EMAIL: 744 if (!x509_constraints_parse_mailbox(bytes, len, 745 vname)) { 746 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 747 goto err; 748 } 749 vname->type = GEN_EMAIL; 750 include_email = 0; /* don't use email from subject */ 751 break; 752 case GEN_URI: 753 if (!x509_constraints_uri_host(bytes, len, &vname->name)) { 754 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 755 goto err; 756 } 757 if (vname->name == NULL) { 758 *error = X509_V_ERR_OUT_OF_MEM; 759 goto err; 760 } 761 vname->type = GEN_URI; 762 break; 763 case GEN_DIRNAME: 764 if (len == 0) { 765 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 766 goto err; 767 } 768 if (bytes == NULL || ((vname->der = malloc(len)) == 769 NULL)) { 770 *error = X509_V_ERR_OUT_OF_MEM; 771 goto err; 772 } 773 memcpy(vname->der, bytes, len); 774 vname->der_len = len; 775 vname->type = GEN_DIRNAME; 776 break; 777 case GEN_IPADD: 778 if (len == 4) 779 vname->af = AF_INET; 780 if (len == 16) 781 vname->af = AF_INET6; 782 if (vname->af != AF_INET && vname->af != AF_INET6) { 783 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 784 goto err; 785 } 786 memcpy(vname->address, bytes, len); 787 vname->type = GEN_IPADD; 788 break; 789 default: 790 /* Ignore this name */ 791 x509_constraints_name_free(vname); 792 vname = NULL; 793 continue; 794 } 795 if (!x509_constraints_names_add(names, vname)) { 796 *error = X509_V_ERR_OUT_OF_MEM; 797 goto err; 798 } 799 vname = NULL; 800 } 801 802 x509_constraints_name_free(vname); 803 vname = NULL; 804 805 subject_name = X509_get_subject_name(cert); 806 if (X509_NAME_entry_count(subject_name) > 0) { 807 X509_NAME_ENTRY *email; 808 X509_NAME_ENTRY *cn; 809 /* 810 * This cert has a non-empty subject, so we must add 811 * the subject as a dirname to be compared against 812 * any dirname constraints 813 */ 814 if ((subject_name->modified && 815 i2d_X509_NAME(subject_name, NULL) < 0) || 816 (vname = x509_constraints_name_new()) == NULL || 817 (vname->der = malloc(subject_name->canon_enclen)) == NULL) { 818 *error = X509_V_ERR_OUT_OF_MEM; 819 goto err; 820 } 821 822 memcpy(vname->der, subject_name->canon_enc, 823 subject_name->canon_enclen); 824 vname->der_len = subject_name->canon_enclen; 825 vname->type = GEN_DIRNAME; 826 if (!x509_constraints_names_add(names, vname)) { 827 *error = X509_V_ERR_OUT_OF_MEM; 828 goto err; 829 } 830 vname = NULL; 831 /* 832 * Get any email addresses from the subject line, and 833 * add them as mbox names to be compared against any 834 * email constraints 835 */ 836 while (include_email && 837 (i = X509_NAME_get_index_by_NID(subject_name, 838 NID_pkcs9_emailAddress, i)) >= 0) { 839 ASN1_STRING *aname; 840 if ((email = X509_NAME_get_entry(subject_name, i)) == NULL || 841 (aname = X509_NAME_ENTRY_get_data(email)) == NULL) { 842 *error = X509_V_ERR_OUT_OF_MEM; 843 goto err; 844 } 845 if ((vname = x509_constraints_name_new()) == NULL) { 846 *error = X509_V_ERR_OUT_OF_MEM; 847 goto err; 848 } 849 if (!x509_constraints_parse_mailbox(aname->data, 850 aname->length, vname)) { 851 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 852 goto err; 853 } 854 vname->type = GEN_EMAIL; 855 if (!x509_constraints_names_add(names, vname)) { 856 *error = X509_V_ERR_OUT_OF_MEM; 857 goto err; 858 } 859 vname = NULL; 860 } 861 /* 862 * Include the CN as a hostname to be checked againt 863 * name constraints if it looks like a hostname. 864 */ 865 while (include_cn && 866 (i = X509_NAME_get_index_by_NID(subject_name, 867 NID_commonName, i)) >= 0) { 868 ASN1_STRING *aname; 869 if ((cn = X509_NAME_get_entry(subject_name, i)) == NULL || 870 (aname = X509_NAME_ENTRY_get_data(cn)) == NULL) { 871 *error = X509_V_ERR_OUT_OF_MEM; 872 goto err; 873 } 874 if (!x509_constraints_valid_host(aname->data, 875 aname->length)) 876 continue; /* ignore it if not a hostname */ 877 if ((vname = x509_constraints_name_new()) == NULL) { 878 *error = X509_V_ERR_OUT_OF_MEM; 879 goto err; 880 } 881 if ((vname->name = strndup(aname->data, 882 aname->length)) == NULL) { 883 *error = X509_V_ERR_OUT_OF_MEM; 884 goto err; 885 } 886 vname->type = GEN_DNS; 887 if (!x509_constraints_names_add(names, vname)) { 888 *error = X509_V_ERR_OUT_OF_MEM; 889 goto err; 890 } 891 vname = NULL; 892 } 893 } 894 return 1; 895 err: 896 x509_constraints_name_free(vname); 897 return 0; 898 } 899 900 /* 901 * Validate a constraint in a general name, putting the relevant data 902 * into "name" if valid. returns 0, and sets error if the constraint is 903 * not valid. returns 1 if the constraint validated. name->type will be 904 * set to a valid type if there is constraint data in name, or unmodified 905 * if the GENERAL_NAME had a valid type but was ignored. 906 */ 907 int 908 x509_constraints_validate(GENERAL_NAME *constraint, 909 struct x509_constraints_name **out_name, int *out_error) 910 { 911 uint8_t *bytes = NULL; 912 size_t len = 0; 913 struct x509_constraints_name *name; 914 int error = X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX; 915 int name_type; 916 917 if (out_name == NULL || *out_name != NULL) 918 return 0; 919 920 if (out_error != NULL) 921 *out_error = 0; 922 923 if ((name = x509_constraints_name_new()) == NULL) { 924 error = X509_V_ERR_OUT_OF_MEM; 925 goto err; 926 } 927 928 name_type = x509_constraints_general_to_bytes(constraint, &bytes, &len); 929 switch (name_type) { 930 case GEN_DIRNAME: 931 if (len == 0) 932 goto err; /* XXX The RFCs are delightfully vague */ 933 if (bytes == NULL || (name->der = malloc(len)) == NULL) { 934 error = X509_V_ERR_OUT_OF_MEM; 935 goto err; 936 } 937 memcpy(name->der, bytes, len); 938 name->der_len = len; 939 name->type = GEN_DIRNAME; 940 break; 941 case GEN_DNS: 942 if (!x509_constraints_valid_domain_constraint(bytes, len)) 943 goto err; 944 if ((name->name = strndup(bytes, len)) == NULL) { 945 error = X509_V_ERR_OUT_OF_MEM; 946 goto err; 947 } 948 name->type = GEN_DNS; 949 break; 950 case GEN_EMAIL: 951 if (len > 0 && memchr(bytes + 1, '@', len - 1) != NULL) { 952 if (!x509_constraints_parse_mailbox(bytes, len, name)) 953 goto err; 954 break; 955 } 956 /* 957 * Mail constraints of the form @domain.com are accepted by 958 * OpenSSL and Microsoft. 959 */ 960 if (len > 0 && bytes[0] == '@') { 961 bytes++; 962 len--; 963 } 964 if (!x509_constraints_valid_domain_constraint(bytes, len)) 965 goto err; 966 if ((name->name = strndup(bytes, len)) == NULL) { 967 error = X509_V_ERR_OUT_OF_MEM; 968 goto err; 969 } 970 name->type = GEN_EMAIL; 971 break; 972 case GEN_IPADD: 973 /* Constraints are ip then mask */ 974 if (len == 8) 975 name->af = AF_INET; 976 else if (len == 32) 977 name->af = AF_INET6; 978 else 979 goto err; 980 memcpy(&name->address[0], bytes, len); 981 name->type = GEN_IPADD; 982 break; 983 case GEN_URI: 984 if (!x509_constraints_valid_domain_constraint(bytes, len)) 985 goto err; 986 if ((name->name = strndup(bytes, len)) == NULL) { 987 error = X509_V_ERR_OUT_OF_MEM; 988 goto err; 989 } 990 name->type = GEN_URI; 991 break; 992 default: 993 break; 994 } 995 996 *out_name = name; 997 998 return 1; 999 1000 err: 1001 x509_constraints_name_free(name); 1002 if (out_error != NULL) 1003 *out_error = error; 1004 1005 return 0; 1006 } 1007 1008 int 1009 x509_constraints_extract_constraints(X509 *cert, 1010 struct x509_constraints_names *permitted, 1011 struct x509_constraints_names *excluded, 1012 int *error) 1013 { 1014 struct x509_constraints_name *vname = NULL; 1015 NAME_CONSTRAINTS *nc = cert->nc; 1016 GENERAL_SUBTREE *subtree; 1017 int i; 1018 1019 if (nc == NULL) 1020 return 1; 1021 1022 for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) { 1023 1024 subtree = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i); 1025 if (subtree->minimum || subtree->maximum) { 1026 *error = X509_V_ERR_SUBTREE_MINMAX; 1027 return 0; 1028 } 1029 if (!x509_constraints_validate(subtree->base, &vname, error)) 1030 return 0; 1031 if (vname->type == 0) { 1032 x509_constraints_name_free(vname); 1033 vname = NULL; 1034 continue; 1035 } 1036 if (!x509_constraints_names_add(permitted, vname)) { 1037 x509_constraints_name_free(vname); 1038 vname = NULL; 1039 *error = X509_V_ERR_OUT_OF_MEM; 1040 return 0; 1041 } 1042 vname = NULL; 1043 } 1044 1045 for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) { 1046 subtree = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i); 1047 if (subtree->minimum || subtree->maximum) { 1048 *error = X509_V_ERR_SUBTREE_MINMAX; 1049 return 0; 1050 } 1051 if (!x509_constraints_validate(subtree->base, &vname, error)) 1052 return 0; 1053 if (vname->type == 0) { 1054 x509_constraints_name_free(vname); 1055 vname = NULL; 1056 continue; 1057 } 1058 if (!x509_constraints_names_add(excluded, vname)) { 1059 x509_constraints_name_free(vname); 1060 vname = NULL; 1061 *error = X509_V_ERR_OUT_OF_MEM; 1062 return 0; 1063 } 1064 vname = NULL; 1065 } 1066 1067 return 1; 1068 } 1069 1070 /* 1071 * Match a validated name in "name" against a validated constraint in 1072 * "constraint" return 1 if then name matches, 0 otherwise. 1073 */ 1074 int 1075 x509_constraints_match(struct x509_constraints_name *name, 1076 struct x509_constraints_name *constraint) 1077 { 1078 if (name->type != constraint->type) 1079 return 0; 1080 if (name->type == GEN_DNS) 1081 return x509_constraints_sandns(name->name, strlen(name->name), 1082 constraint->name, strlen(constraint->name)); 1083 if (name->type == GEN_URI) 1084 return x509_constraints_domain(name->name, strlen(name->name), 1085 constraint->name, strlen(constraint->name)); 1086 if (name->type == GEN_IPADD) { 1087 size_t nlen = name->af == AF_INET ? 4 : 16; 1088 size_t clen = name->af == AF_INET ? 8 : 32; 1089 if (name->af != AF_INET && name->af != AF_INET6) 1090 return 0; 1091 if (constraint->af != AF_INET && constraint->af != AF_INET6) 1092 return 0; 1093 if (name->af != constraint->af) 1094 return 0; 1095 return x509_constraints_ipaddr(name->address, nlen, 1096 constraint->address, clen); 1097 } 1098 if (name->type == GEN_EMAIL) { 1099 if (constraint->local) { 1100 /* mailbox local and domain parts must exactly match */ 1101 return (strcmp(name->local, constraint->local) == 0 && 1102 strcmp(name->name, constraint->name) == 0); 1103 } 1104 /* otherwise match the constraint to the domain part */ 1105 return x509_constraints_domain(name->name, strlen(name->name), 1106 constraint->name, strlen(constraint->name)); 1107 } 1108 if (name->type == GEN_DIRNAME) 1109 return x509_constraints_dirname(name->der, name->der_len, 1110 constraint->der, constraint->der_len); 1111 return 0; 1112 } 1113 1114 /* 1115 * Make sure every name in names does not match any excluded 1116 * constraints, and does match at least one permitted constraint if 1117 * any are present. Returns 1 if ok, 0, and sets error if not. 1118 */ 1119 int 1120 x509_constraints_check(struct x509_constraints_names *names, 1121 struct x509_constraints_names *permitted, 1122 struct x509_constraints_names *excluded, int *error) 1123 { 1124 size_t i, j; 1125 1126 for (i = 0; i < names->names_count; i++) { 1127 int permitted_seen = 0; 1128 int permitted_matched = 0; 1129 1130 for (j = 0; j < excluded->names_count; j++) { 1131 if (x509_constraints_match(names->names[i], 1132 excluded->names[j])) { 1133 *error = X509_V_ERR_EXCLUDED_VIOLATION; 1134 return 0; 1135 } 1136 } 1137 for (j = 0; j < permitted->names_count; j++) { 1138 if (permitted->names[j]->type == names->names[i]->type) 1139 permitted_seen++; 1140 if (x509_constraints_match(names->names[i], 1141 permitted->names[j])) { 1142 permitted_matched++; 1143 break; 1144 } 1145 } 1146 if (permitted_seen && !permitted_matched) { 1147 *error = X509_V_ERR_PERMITTED_VIOLATION; 1148 return 0; 1149 } 1150 } 1151 return 1; 1152 } 1153 1154 /* 1155 * Walk a validated chain of X509 certs, starting at the leaf, and 1156 * validate the name constraints in the chain. Intended for use with 1157 * the legacy X509 validtion code in x509_vfy.c 1158 * 1159 * returns 1 if the constraints are ok, 0 otherwise, setting error and 1160 * depth 1161 */ 1162 int 1163 x509_constraints_chain(STACK_OF(X509) *chain, int *error, int *depth) 1164 { 1165 int chain_length, verify_err = X509_V_ERR_UNSPECIFIED, i = 0; 1166 struct x509_constraints_names *names = NULL; 1167 struct x509_constraints_names *excluded = NULL; 1168 struct x509_constraints_names *permitted = NULL; 1169 size_t constraints_count = 0; 1170 X509 *cert; 1171 1172 if (chain == NULL || (chain_length = sk_X509_num(chain)) == 0) 1173 goto err; 1174 if (chain_length == 1) 1175 return 1; 1176 if ((names = x509_constraints_names_new( 1177 X509_VERIFY_MAX_CHAIN_NAMES)) == NULL) { 1178 verify_err = X509_V_ERR_OUT_OF_MEM; 1179 goto err; 1180 } 1181 1182 if ((cert = sk_X509_value(chain, 0)) == NULL) 1183 goto err; 1184 if (!x509_constraints_extract_names(names, cert, 1, &verify_err)) 1185 goto err; 1186 for (i = 1; i < chain_length; i++) { 1187 if ((cert = sk_X509_value(chain, i)) == NULL) 1188 goto err; 1189 if (cert->nc != NULL) { 1190 if ((permitted = x509_constraints_names_new( 1191 X509_VERIFY_MAX_CHAIN_CONSTRAINTS)) == NULL) { 1192 verify_err = X509_V_ERR_OUT_OF_MEM; 1193 goto err; 1194 } 1195 if ((excluded = x509_constraints_names_new( 1196 X509_VERIFY_MAX_CHAIN_CONSTRAINTS)) == NULL) { 1197 verify_err = X509_V_ERR_OUT_OF_MEM; 1198 goto err; 1199 } 1200 if (!x509_constraints_extract_constraints(cert, 1201 permitted, excluded, &verify_err)) 1202 goto err; 1203 constraints_count += permitted->names_count; 1204 constraints_count += excluded->names_count; 1205 if (constraints_count > 1206 X509_VERIFY_MAX_CHAIN_CONSTRAINTS) { 1207 verify_err = X509_V_ERR_OUT_OF_MEM; 1208 goto err; 1209 } 1210 if (!x509_constraints_check(names, permitted, excluded, 1211 &verify_err)) 1212 goto err; 1213 x509_constraints_names_free(excluded); 1214 excluded = NULL; 1215 x509_constraints_names_free(permitted); 1216 permitted = NULL; 1217 } 1218 if (!x509_constraints_extract_names(names, cert, 0, 1219 &verify_err)) 1220 goto err; 1221 } 1222 1223 x509_constraints_names_free(names); 1224 return 1; 1225 1226 err: 1227 *error = verify_err; 1228 *depth = i; 1229 x509_constraints_names_free(excluded); 1230 x509_constraints_names_free(permitted); 1231 x509_constraints_names_free(names); 1232 return 0; 1233 } 1234