1 /* $OpenBSD: x509_constraints.c,v 1.27 2022/06/26 11:29:27 beck 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 /* 494 * There is no authority, so no host part in this 495 * URI. This might be ok or might not, but it must 496 * fail if we run into a name constraint later, so 497 * we indicate that we have a URI with an empty 498 * host part, and succeed. 499 */ 500 *hostpart = strdup(""); 501 return 1; 502 } 503 for (i = authority - uri; i < len; i++) { 504 if (!isascii(uri[i])) 505 return 0; 506 /* it has a userinfo part */ 507 if (uri[i] == '@') { 508 hostlen = 0; 509 /* it can only have one */ 510 if (host != NULL) 511 break; 512 /* start after the userinfo part */ 513 host = uri + i + 1; 514 continue; 515 } 516 /* did we find the end? */ 517 if (uri[i] == ':' || uri[i] == '/' || uri[i] == '?' || 518 uri[i] == '#') 519 break; 520 hostlen++; 521 } 522 if (hostlen == 0) 523 return 0; 524 if (host == NULL) 525 host = authority; 526 if (!x509_constraints_valid_host(host, hostlen)) 527 return 0; 528 if (hostpart != NULL) 529 *hostpart = strndup(host, hostlen); 530 return 1; 531 } 532 533 int 534 x509_constraints_sandns(char *sandns, size_t dlen, char *constraint, size_t len) 535 { 536 char *suffix; 537 538 if (len == 0) 539 return 1; /* an empty constraint matches everything */ 540 541 /* match the end of the domain */ 542 if (dlen < len) 543 return 0; 544 suffix = sandns + (dlen - len); 545 return (strncasecmp(suffix, constraint, len) == 0); 546 } 547 548 /* 549 * Validate a pre-validated domain of length dlen against a pre-validated 550 * constraint of length len. 551 * 552 * returns 1 if the domain and constraint match. 553 * returns 0 otherwise. 554 * 555 * an empty constraint matches everyting. 556 * constraint will be matched against the domain as a suffix if it 557 * starts with a '.'. 558 * domain will be matched against the constraint as a suffix if it 559 * starts with a '.'. 560 */ 561 int 562 x509_constraints_domain(char *domain, size_t dlen, char *constraint, size_t len) 563 { 564 if (len == 0) 565 return 1; /* an empty constraint matches everything */ 566 567 if (constraint[0] == '.') { 568 /* match the end of the domain */ 569 char *suffix; 570 if (dlen < len) 571 return 0; 572 suffix = domain + (dlen - len); 573 return (strncasecmp(suffix, constraint, len) == 0); 574 } 575 if (domain[0] == '.') { 576 /* match the end of the constraint */ 577 char *suffix; 578 if (len < dlen) 579 return 0; 580 suffix = constraint + (len - dlen); 581 return (strncasecmp(suffix, domain, dlen) == 0); 582 } 583 /* otherwise we must exactly match the constraint */ 584 if (dlen != len) 585 return 0; 586 return (strncasecmp(domain, constraint, len) == 0); 587 } 588 589 int 590 x509_constraints_uri(uint8_t *uri, size_t ulen, uint8_t *constraint, size_t len, 591 int *error) 592 { 593 int ret = 0; 594 char *hostpart = NULL; 595 596 if (!x509_constraints_uri_host(uri, ulen, &hostpart)) { 597 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 598 goto err; 599 } 600 if (hostpart == NULL) { 601 *error = X509_V_ERR_OUT_OF_MEM; 602 goto err; 603 } 604 if (!x509_constraints_valid_domain_constraint(constraint, len)) { 605 *error = X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX; 606 goto err; 607 } 608 ret = x509_constraints_domain(hostpart, strlen(hostpart), constraint, 609 len); 610 err: 611 free(hostpart); 612 return ret; 613 } 614 615 /* 616 * Verify a validated address of size alen with a validated contraint 617 * of size constraint_len. returns 1 if matching, 0 if not. 618 * Addresses are assumed to be pre-validated for a length of 4 and 8 619 * respectively for ipv4 addreses and constraints, and a length of 620 * 16 and 32 respectively for ipv6 address constraints by the caller. 621 */ 622 int 623 x509_constraints_ipaddr(uint8_t *address, size_t alen, uint8_t *constraint, 624 size_t len) 625 { 626 uint8_t *mask; 627 size_t i; 628 629 if (alen * 2 != len) 630 return 0; 631 632 mask = constraint + alen; 633 for (i = 0; i < alen; i++) { 634 if ((address[i] & mask[i]) != (constraint[i] & mask[i])) 635 return 0; 636 } 637 return 1; 638 } 639 640 /* 641 * Verify a canonicalized der encoded constraint dirname 642 * a canonicalized der encoded constraint. 643 */ 644 int 645 x509_constraints_dirname(uint8_t *dirname, size_t dlen, 646 uint8_t *constraint, size_t len) 647 { 648 /* 649 * The constraint must be a prefix in DER format, so it can't be 650 * longer than the name it is checked against. 651 */ 652 if (len > dlen) 653 return 0; 654 return (memcmp(constraint, dirname, len) == 0); 655 } 656 657 /* 658 * De-obfuscate a GENERAL_NAME into useful bytes for a name or constraint. 659 */ 660 int 661 x509_constraints_general_to_bytes(GENERAL_NAME *name, uint8_t **bytes, 662 size_t *len) 663 { 664 *bytes = NULL; 665 *len = 0; 666 667 if (name->type == GEN_DNS) { 668 ASN1_IA5STRING *aname = name->d.dNSName; 669 670 *bytes = aname->data; 671 *len = aname->length; 672 673 return name->type; 674 } 675 if (name->type == GEN_EMAIL) { 676 ASN1_IA5STRING *aname = name->d.rfc822Name; 677 678 *bytes = aname->data; 679 *len = aname->length; 680 681 return name->type; 682 } 683 if (name->type == GEN_URI) { 684 ASN1_IA5STRING *aname = name->d.uniformResourceIdentifier; 685 686 *bytes = aname->data; 687 *len = aname->length; 688 689 return name->type; 690 } 691 if (name->type == GEN_DIRNAME) { 692 X509_NAME *dname = name->d.directoryName; 693 694 if (!dname->modified || i2d_X509_NAME(dname, NULL) >= 0) { 695 *bytes = dname->canon_enc; 696 *len = dname->canon_enclen; 697 698 return name->type; 699 } 700 } 701 if (name->type == GEN_IPADD) { 702 *bytes = name->d.ip->data; 703 *len = name->d.ip->length; 704 705 return name->type; 706 } 707 708 return 0; 709 } 710 711 712 /* 713 * Extract the relevant names for constraint checking from "cert", 714 * validate them, and add them to the list of cert names for "chain". 715 * returns 1 on success sets error and returns 0 on failure. 716 */ 717 int 718 x509_constraints_extract_names(struct x509_constraints_names *names, 719 X509 *cert, int is_leaf, int *error) 720 { 721 struct x509_constraints_name *vname = NULL; 722 X509_NAME *subject_name; 723 GENERAL_NAME *name; 724 ssize_t i = 0; 725 int name_type, include_cn = is_leaf, include_email = is_leaf; 726 727 /* first grab the altnames */ 728 while ((name = sk_GENERAL_NAME_value(cert->altname, i++)) != NULL) { 729 uint8_t *bytes = NULL; 730 size_t len = 0; 731 732 if ((vname = x509_constraints_name_new()) == NULL) { 733 *error = X509_V_ERR_OUT_OF_MEM; 734 goto err; 735 } 736 737 name_type = x509_constraints_general_to_bytes(name, &bytes, 738 &len); 739 switch(name_type) { 740 case GEN_DNS: 741 if (!x509_constraints_valid_sandns(bytes, len)) { 742 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 743 goto err; 744 } 745 if ((vname->name = strndup(bytes, len)) == NULL) { 746 *error = X509_V_ERR_OUT_OF_MEM; 747 goto err; 748 } 749 vname->type = GEN_DNS; 750 include_cn = 0; /* don't use cn from subject */ 751 break; 752 case GEN_EMAIL: 753 if (!x509_constraints_parse_mailbox(bytes, len, 754 vname)) { 755 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 756 goto err; 757 } 758 vname->type = GEN_EMAIL; 759 include_email = 0; /* don't use email from subject */ 760 break; 761 case GEN_URI: 762 if (!x509_constraints_uri_host(bytes, len, &vname->name)) { 763 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 764 goto err; 765 } 766 if (vname->name == NULL) { 767 *error = X509_V_ERR_OUT_OF_MEM; 768 goto err; 769 } 770 vname->type = GEN_URI; 771 break; 772 case GEN_DIRNAME: 773 if (len == 0) { 774 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 775 goto err; 776 } 777 if (bytes == NULL || ((vname->der = malloc(len)) == 778 NULL)) { 779 *error = X509_V_ERR_OUT_OF_MEM; 780 goto err; 781 } 782 memcpy(vname->der, bytes, len); 783 vname->der_len = len; 784 vname->type = GEN_DIRNAME; 785 break; 786 case GEN_IPADD: 787 if (len == 4) 788 vname->af = AF_INET; 789 if (len == 16) 790 vname->af = AF_INET6; 791 if (vname->af != AF_INET && vname->af != AF_INET6) { 792 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 793 goto err; 794 } 795 memcpy(vname->address, bytes, len); 796 vname->type = GEN_IPADD; 797 break; 798 default: 799 /* Ignore this name */ 800 x509_constraints_name_free(vname); 801 vname = NULL; 802 continue; 803 } 804 if (!x509_constraints_names_add(names, vname)) { 805 *error = X509_V_ERR_OUT_OF_MEM; 806 goto err; 807 } 808 vname = NULL; 809 } 810 811 x509_constraints_name_free(vname); 812 vname = NULL; 813 814 subject_name = X509_get_subject_name(cert); 815 if (X509_NAME_entry_count(subject_name) > 0) { 816 X509_NAME_ENTRY *email; 817 X509_NAME_ENTRY *cn; 818 /* 819 * This cert has a non-empty subject, so we must add 820 * the subject as a dirname to be compared against 821 * any dirname constraints 822 */ 823 if ((subject_name->modified && 824 i2d_X509_NAME(subject_name, NULL) < 0) || 825 (vname = x509_constraints_name_new()) == NULL || 826 (vname->der = malloc(subject_name->canon_enclen)) == NULL) { 827 *error = X509_V_ERR_OUT_OF_MEM; 828 goto err; 829 } 830 831 memcpy(vname->der, subject_name->canon_enc, 832 subject_name->canon_enclen); 833 vname->der_len = subject_name->canon_enclen; 834 vname->type = GEN_DIRNAME; 835 if (!x509_constraints_names_add(names, vname)) { 836 *error = X509_V_ERR_OUT_OF_MEM; 837 goto err; 838 } 839 vname = NULL; 840 /* 841 * Get any email addresses from the subject line, and 842 * add them as mbox names to be compared against any 843 * email constraints 844 */ 845 while (include_email && 846 (i = X509_NAME_get_index_by_NID(subject_name, 847 NID_pkcs9_emailAddress, i)) >= 0) { 848 ASN1_STRING *aname; 849 if ((email = X509_NAME_get_entry(subject_name, i)) == NULL || 850 (aname = X509_NAME_ENTRY_get_data(email)) == NULL) { 851 *error = X509_V_ERR_OUT_OF_MEM; 852 goto err; 853 } 854 if ((vname = x509_constraints_name_new()) == NULL) { 855 *error = X509_V_ERR_OUT_OF_MEM; 856 goto err; 857 } 858 if (!x509_constraints_parse_mailbox(aname->data, 859 aname->length, vname)) { 860 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 861 goto err; 862 } 863 vname->type = GEN_EMAIL; 864 if (!x509_constraints_names_add(names, vname)) { 865 *error = X509_V_ERR_OUT_OF_MEM; 866 goto err; 867 } 868 vname = NULL; 869 } 870 /* 871 * Include the CN as a hostname to be checked againt 872 * name constraints if it looks like a hostname. 873 */ 874 while (include_cn && 875 (i = X509_NAME_get_index_by_NID(subject_name, 876 NID_commonName, i)) >= 0) { 877 ASN1_STRING *aname; 878 if ((cn = X509_NAME_get_entry(subject_name, i)) == NULL || 879 (aname = X509_NAME_ENTRY_get_data(cn)) == NULL) { 880 *error = X509_V_ERR_OUT_OF_MEM; 881 goto err; 882 } 883 if (!x509_constraints_valid_host(aname->data, 884 aname->length)) 885 continue; /* ignore it if not a hostname */ 886 if ((vname = x509_constraints_name_new()) == NULL) { 887 *error = X509_V_ERR_OUT_OF_MEM; 888 goto err; 889 } 890 if ((vname->name = strndup(aname->data, 891 aname->length)) == NULL) { 892 *error = X509_V_ERR_OUT_OF_MEM; 893 goto err; 894 } 895 vname->type = GEN_DNS; 896 if (!x509_constraints_names_add(names, vname)) { 897 *error = X509_V_ERR_OUT_OF_MEM; 898 goto err; 899 } 900 vname = NULL; 901 } 902 } 903 return 1; 904 err: 905 x509_constraints_name_free(vname); 906 return 0; 907 } 908 909 /* 910 * Validate a constraint in a general name, putting the relevant data 911 * into "name" if valid. returns 0, and sets error if the constraint is 912 * not valid. returns 1 if the constraint validated. name->type will be 913 * set to a valid type if there is constraint data in name, or unmodified 914 * if the GENERAL_NAME had a valid type but was ignored. 915 */ 916 int 917 x509_constraints_validate(GENERAL_NAME *constraint, 918 struct x509_constraints_name **out_name, int *out_error) 919 { 920 uint8_t *bytes = NULL; 921 size_t len = 0; 922 struct x509_constraints_name *name; 923 int error = X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX; 924 int name_type; 925 926 if (out_name == NULL || *out_name != NULL) 927 return 0; 928 929 if (out_error != NULL) 930 *out_error = 0; 931 932 if ((name = x509_constraints_name_new()) == NULL) { 933 error = X509_V_ERR_OUT_OF_MEM; 934 goto err; 935 } 936 937 name_type = x509_constraints_general_to_bytes(constraint, &bytes, &len); 938 switch (name_type) { 939 case GEN_DIRNAME: 940 if (len == 0) 941 goto err; /* XXX The RFCs are delightfully vague */ 942 if (bytes == NULL || (name->der = malloc(len)) == NULL) { 943 error = X509_V_ERR_OUT_OF_MEM; 944 goto err; 945 } 946 memcpy(name->der, bytes, len); 947 name->der_len = len; 948 name->type = GEN_DIRNAME; 949 break; 950 case GEN_DNS: 951 if (!x509_constraints_valid_domain_constraint(bytes, len)) 952 goto err; 953 if ((name->name = strndup(bytes, len)) == NULL) { 954 error = X509_V_ERR_OUT_OF_MEM; 955 goto err; 956 } 957 name->type = GEN_DNS; 958 break; 959 case GEN_EMAIL: 960 if (len > 0 && memchr(bytes + 1, '@', len - 1) != NULL) { 961 if (!x509_constraints_parse_mailbox(bytes, len, name)) 962 goto err; 963 break; 964 } 965 /* 966 * Mail constraints of the form @domain.com are accepted by 967 * OpenSSL and Microsoft. 968 */ 969 if (len > 0 && bytes[0] == '@') { 970 bytes++; 971 len--; 972 } 973 if (!x509_constraints_valid_domain_constraint(bytes, len)) 974 goto err; 975 if ((name->name = strndup(bytes, len)) == NULL) { 976 error = X509_V_ERR_OUT_OF_MEM; 977 goto err; 978 } 979 name->type = GEN_EMAIL; 980 break; 981 case GEN_IPADD: 982 /* Constraints are ip then mask */ 983 if (len == 8) 984 name->af = AF_INET; 985 else if (len == 32) 986 name->af = AF_INET6; 987 else 988 goto err; 989 memcpy(&name->address[0], bytes, len); 990 name->type = GEN_IPADD; 991 break; 992 case GEN_URI: 993 if (!x509_constraints_valid_domain_constraint(bytes, len)) 994 goto err; 995 if ((name->name = strndup(bytes, len)) == NULL) { 996 error = X509_V_ERR_OUT_OF_MEM; 997 goto err; 998 } 999 name->type = GEN_URI; 1000 break; 1001 default: 1002 break; 1003 } 1004 1005 *out_name = name; 1006 1007 return 1; 1008 1009 err: 1010 x509_constraints_name_free(name); 1011 if (out_error != NULL) 1012 *out_error = error; 1013 1014 return 0; 1015 } 1016 1017 int 1018 x509_constraints_extract_constraints(X509 *cert, 1019 struct x509_constraints_names *permitted, 1020 struct x509_constraints_names *excluded, 1021 int *error) 1022 { 1023 struct x509_constraints_name *vname = NULL; 1024 NAME_CONSTRAINTS *nc = cert->nc; 1025 GENERAL_SUBTREE *subtree; 1026 int i; 1027 1028 if (nc == NULL) 1029 return 1; 1030 1031 for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) { 1032 1033 subtree = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i); 1034 if (subtree->minimum || subtree->maximum) { 1035 *error = X509_V_ERR_SUBTREE_MINMAX; 1036 return 0; 1037 } 1038 if (!x509_constraints_validate(subtree->base, &vname, error)) 1039 return 0; 1040 if (vname->type == 0) { 1041 x509_constraints_name_free(vname); 1042 vname = NULL; 1043 continue; 1044 } 1045 if (!x509_constraints_names_add(permitted, vname)) { 1046 x509_constraints_name_free(vname); 1047 vname = NULL; 1048 *error = X509_V_ERR_OUT_OF_MEM; 1049 return 0; 1050 } 1051 vname = NULL; 1052 } 1053 1054 for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) { 1055 subtree = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i); 1056 if (subtree->minimum || subtree->maximum) { 1057 *error = X509_V_ERR_SUBTREE_MINMAX; 1058 return 0; 1059 } 1060 if (!x509_constraints_validate(subtree->base, &vname, error)) 1061 return 0; 1062 if (vname->type == 0) { 1063 x509_constraints_name_free(vname); 1064 vname = NULL; 1065 continue; 1066 } 1067 if (!x509_constraints_names_add(excluded, vname)) { 1068 x509_constraints_name_free(vname); 1069 vname = NULL; 1070 *error = X509_V_ERR_OUT_OF_MEM; 1071 return 0; 1072 } 1073 vname = NULL; 1074 } 1075 1076 return 1; 1077 } 1078 1079 /* 1080 * Match a validated name in "name" against a validated constraint in 1081 * "constraint" return 1 if then name matches, 0 otherwise. 1082 */ 1083 int 1084 x509_constraints_match(struct x509_constraints_name *name, 1085 struct x509_constraints_name *constraint) 1086 { 1087 if (name->type != constraint->type) 1088 return 0; 1089 if (name->type == GEN_DNS) 1090 return x509_constraints_sandns(name->name, strlen(name->name), 1091 constraint->name, strlen(constraint->name)); 1092 if (name->type == GEN_URI) 1093 return x509_constraints_domain(name->name, strlen(name->name), 1094 constraint->name, strlen(constraint->name)); 1095 if (name->type == GEN_IPADD) { 1096 size_t nlen = name->af == AF_INET ? 4 : 16; 1097 size_t clen = name->af == AF_INET ? 8 : 32; 1098 if (name->af != AF_INET && name->af != AF_INET6) 1099 return 0; 1100 if (constraint->af != AF_INET && constraint->af != AF_INET6) 1101 return 0; 1102 if (name->af != constraint->af) 1103 return 0; 1104 return x509_constraints_ipaddr(name->address, nlen, 1105 constraint->address, clen); 1106 } 1107 if (name->type == GEN_EMAIL) { 1108 if (constraint->local) { 1109 /* mailbox local and domain parts must exactly match */ 1110 return (strcmp(name->local, constraint->local) == 0 && 1111 strcmp(name->name, constraint->name) == 0); 1112 } 1113 /* otherwise match the constraint to the domain part */ 1114 return x509_constraints_domain(name->name, strlen(name->name), 1115 constraint->name, strlen(constraint->name)); 1116 } 1117 if (name->type == GEN_DIRNAME) 1118 return x509_constraints_dirname(name->der, name->der_len, 1119 constraint->der, constraint->der_len); 1120 return 0; 1121 } 1122 1123 /* 1124 * Make sure every name in names does not match any excluded 1125 * constraints, and does match at least one permitted constraint if 1126 * any are present. Returns 1 if ok, 0, and sets error if not. 1127 */ 1128 int 1129 x509_constraints_check(struct x509_constraints_names *names, 1130 struct x509_constraints_names *permitted, 1131 struct x509_constraints_names *excluded, int *error) 1132 { 1133 size_t i, j; 1134 1135 for (i = 0; i < names->names_count; i++) { 1136 int permitted_seen = 0; 1137 int permitted_matched = 0; 1138 1139 for (j = 0; j < excluded->names_count; j++) { 1140 if (x509_constraints_match(names->names[i], 1141 excluded->names[j])) { 1142 *error = X509_V_ERR_EXCLUDED_VIOLATION; 1143 return 0; 1144 } 1145 } 1146 for (j = 0; j < permitted->names_count; j++) { 1147 if (permitted->names[j]->type == names->names[i]->type) 1148 permitted_seen++; 1149 if (x509_constraints_match(names->names[i], 1150 permitted->names[j])) { 1151 permitted_matched++; 1152 break; 1153 } 1154 } 1155 if (permitted_seen && !permitted_matched) { 1156 *error = X509_V_ERR_PERMITTED_VIOLATION; 1157 return 0; 1158 } 1159 } 1160 return 1; 1161 } 1162 1163 /* 1164 * Walk a validated chain of X509 certs, starting at the leaf, and 1165 * validate the name constraints in the chain. Intended for use with 1166 * the legacy X509 validtion code in x509_vfy.c 1167 * 1168 * returns 1 if the constraints are ok, 0 otherwise, setting error and 1169 * depth 1170 */ 1171 int 1172 x509_constraints_chain(STACK_OF(X509) *chain, int *error, int *depth) 1173 { 1174 int chain_length, verify_err = X509_V_ERR_UNSPECIFIED, i = 0; 1175 struct x509_constraints_names *names = NULL; 1176 struct x509_constraints_names *excluded = NULL; 1177 struct x509_constraints_names *permitted = NULL; 1178 size_t constraints_count = 0; 1179 X509 *cert; 1180 1181 if (chain == NULL || (chain_length = sk_X509_num(chain)) == 0) 1182 goto err; 1183 if (chain_length == 1) 1184 return 1; 1185 if ((names = x509_constraints_names_new( 1186 X509_VERIFY_MAX_CHAIN_NAMES)) == NULL) { 1187 verify_err = X509_V_ERR_OUT_OF_MEM; 1188 goto err; 1189 } 1190 1191 if ((cert = sk_X509_value(chain, 0)) == NULL) 1192 goto err; 1193 if (!x509_constraints_extract_names(names, cert, 1, &verify_err)) 1194 goto err; 1195 for (i = 1; i < chain_length; i++) { 1196 if ((cert = sk_X509_value(chain, i)) == NULL) 1197 goto err; 1198 if (cert->nc != NULL) { 1199 if ((permitted = x509_constraints_names_new( 1200 X509_VERIFY_MAX_CHAIN_CONSTRAINTS)) == NULL) { 1201 verify_err = X509_V_ERR_OUT_OF_MEM; 1202 goto err; 1203 } 1204 if ((excluded = x509_constraints_names_new( 1205 X509_VERIFY_MAX_CHAIN_CONSTRAINTS)) == NULL) { 1206 verify_err = X509_V_ERR_OUT_OF_MEM; 1207 goto err; 1208 } 1209 if (!x509_constraints_extract_constraints(cert, 1210 permitted, excluded, &verify_err)) 1211 goto err; 1212 constraints_count += permitted->names_count; 1213 constraints_count += excluded->names_count; 1214 if (constraints_count > 1215 X509_VERIFY_MAX_CHAIN_CONSTRAINTS) { 1216 verify_err = X509_V_ERR_OUT_OF_MEM; 1217 goto err; 1218 } 1219 if (!x509_constraints_check(names, permitted, excluded, 1220 &verify_err)) 1221 goto err; 1222 x509_constraints_names_free(excluded); 1223 excluded = NULL; 1224 x509_constraints_names_free(permitted); 1225 permitted = NULL; 1226 } 1227 if (!x509_constraints_extract_names(names, cert, 0, 1228 &verify_err)) 1229 goto err; 1230 } 1231 1232 x509_constraints_names_free(names); 1233 return 1; 1234 1235 err: 1236 *error = verify_err; 1237 *depth = i; 1238 x509_constraints_names_free(excluded); 1239 x509_constraints_names_free(permitted); 1240 x509_constraints_names_free(names); 1241 return 0; 1242 } 1243