1 /* $OpenBSD: x509_constraints.c,v 1.16 2021/04/27 03:35:29 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 (wi > DOMAIN_PART_MAX_LEN) 343 goto bad; 344 if (accept) { 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 working[wi++] = c; 387 continue; /* all's good inside our quoted string */ 388 } 389 if (c == '@') { 390 if (wi == 0) 391 goto bad;; 392 if (candidate_local != NULL) 393 goto bad; 394 candidate_local = strdup(working); 395 if (candidate_local == NULL) 396 goto bad; 397 memset(working, 0, sizeof(working)); 398 wi = 0; 399 continue; 400 } 401 if (c == '\\') { 402 /* 403 * RFC 3936 hints these can happen outside of 404 * quotend string. don't include the \ but 405 * next character must be ok. 406 */ 407 if (i + 1 == len) 408 goto bad; 409 if (!local_part_ok(candidate[i + 1])) 410 goto bad; 411 accept = 1; 412 } 413 if (!local_part_ok(c)) 414 goto bad; 415 working[wi++] = c; 416 } 417 if (candidate_local == NULL || candidate_domain == NULL) 418 goto bad; 419 if (!x509_constraints_valid_host(candidate_domain, 420 strlen(candidate_domain))) 421 goto bad; 422 423 name->local = candidate_local; 424 name->name = candidate_domain; 425 name->type = GEN_EMAIL; 426 return 1; 427 bad: 428 free(candidate_local); 429 free(candidate_domain); 430 return 0; 431 } 432 433 int 434 x509_constraints_valid_domain_constraint(uint8_t *constraint, size_t len) 435 { 436 if (len == 0) 437 return 1; /* empty constraints match */ 438 439 /* 440 * A domain may not be less than two characters, so you 441 * can't match a single domain of less than that 442 */ 443 if (len < 3 && constraint[0] == '.') 444 return 0; 445 return x509_constraints_valid_domain_internal(constraint, len, 0); 446 } 447 448 /* 449 * Extract the host part of a URI, returns the host part as a c string 450 * the caller must free, or or NULL if it could not be found or is 451 * invalid. 452 * 453 * RFC 3986: 454 * the authority part of a uri starts with // and is terminated with 455 * the next '/', '?', '#' or end of the URI. 456 * 457 * The authority itself contains [userinfo '@'] host [: port] 458 * 459 * so the host starts at the start or after the '@', and ends 460 * with end of URI, '/', '?', "#', or ':'. 461 */ 462 int 463 x509_constraints_uri_host(uint8_t *uri, size_t len, char **hostpart) 464 { 465 size_t i, hostlen = 0; 466 uint8_t *authority = NULL; 467 char *host = NULL; 468 469 /* 470 * Find first '//'. there must be at least a '//' and 471 * something else. 472 */ 473 if (len < 3) 474 return 0; 475 for (i = 0; i < len - 1; i++) { 476 if (!isascii(uri[i])) 477 return 0; 478 if (uri[i] == '/' && uri[i + 1] == '/') { 479 authority = uri + i + 2; 480 break; 481 } 482 } 483 if (authority == NULL) 484 return 0; 485 for (i = authority - uri; i < len; i++) { 486 if (!isascii(uri[i])) 487 return 0; 488 /* it has a userinfo part */ 489 if (uri[i] == '@') { 490 hostlen = 0; 491 /* it can only have one */ 492 if (host != NULL) 493 break; 494 /* start after the userinfo part */ 495 host = uri + i + 1; 496 continue; 497 } 498 /* did we find the end? */ 499 if (uri[i] == ':' || uri[i] == '/' || uri[i] == '?' || 500 uri[i] == '#') 501 break; 502 hostlen++; 503 } 504 if (hostlen == 0) 505 return 0; 506 if (host == NULL) 507 host = authority; 508 if (!x509_constraints_valid_host(host, hostlen)) 509 return 0; 510 *hostpart = strndup(host, hostlen); 511 return 1; 512 } 513 514 int 515 x509_constraints_sandns(char *sandns, size_t dlen, char *constraint, size_t len) 516 { 517 char *suffix; 518 519 if (len == 0) 520 return 1; /* an empty constraint matches everything */ 521 522 /* match the end of the domain */ 523 if (dlen < len) 524 return 0; 525 suffix = sandns + (dlen - len); 526 return (strncasecmp(suffix, constraint, len) == 0); 527 } 528 529 /* 530 * Validate a pre-validated domain of length dlen against a pre-validated 531 * constraint of length len. 532 * 533 * returns 1 if the domain and constraint match. 534 * returns 0 otherwise. 535 * 536 * an empty constraint matches everyting. 537 * constraint will be matched against the domain as a suffix if it 538 * starts with a '.'. 539 * domain will be matched against the constraint as a suffix if it 540 * starts with a '.'. 541 */ 542 int 543 x509_constraints_domain(char *domain, size_t dlen, char *constraint, size_t len) 544 { 545 if (len == 0) 546 return 1; /* an empty constraint matches everything */ 547 548 if (constraint[0] == '.') { 549 /* match the end of the domain */ 550 char *suffix; 551 if (dlen < len) 552 return 0; 553 suffix = domain + (dlen - len); 554 return (strncasecmp(suffix, constraint, len) == 0); 555 } 556 if (domain[0] == '.') { 557 /* match the end of the constraint */ 558 char *suffix; 559 if (len < dlen) 560 return 0; 561 suffix = constraint + (len - dlen); 562 return (strncasecmp(suffix, domain, dlen) == 0); 563 } 564 /* otherwise we must exactly match the constraint */ 565 if (dlen != len) 566 return 0; 567 return (strncasecmp(domain, constraint, len) == 0); 568 } 569 570 int 571 x509_constraints_uri(uint8_t *uri, size_t ulen, uint8_t *constraint, size_t len, 572 int *error) 573 { 574 int ret = 0; 575 char *hostpart = NULL; 576 577 if (!x509_constraints_uri_host(uri, ulen, &hostpart)) { 578 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 579 goto err; 580 } 581 if (hostpart == NULL) { 582 *error = X509_V_ERR_OUT_OF_MEM; 583 goto err; 584 } 585 if (!x509_constraints_valid_domain_constraint(constraint, len)) { 586 *error = X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX; 587 goto err; 588 } 589 ret = x509_constraints_domain(hostpart, strlen(hostpart), constraint, 590 len); 591 err: 592 free(hostpart); 593 return ret; 594 } 595 596 /* 597 * Verify a validated address of size alen with a validated contraint 598 * of size constraint_len. returns 1 if matching, 0 if not. 599 * Addresses are assumed to be pre-validated for a length of 4 and 8 600 * respectively for ipv4 addreses and constraints, and a length of 601 * 16 and 32 respectively for ipv6 address constraints by the caller. 602 */ 603 int 604 x509_constraints_ipaddr(uint8_t *address, size_t alen, uint8_t *constraint, 605 size_t len) 606 { 607 uint8_t *mask; 608 size_t i; 609 610 if (alen * 2 != len) 611 return 0; 612 613 mask = constraint + alen; 614 for (i = 0; i < alen; i++) { 615 if ((address[i] & mask[i]) != (constraint[i] & mask[i])) 616 return 0; 617 } 618 return 1; 619 } 620 621 /* 622 * Verify a canonicalized der encoded constraint dirname 623 * a canonicalized der encoded constraint. 624 */ 625 int 626 x509_constraints_dirname(uint8_t *dirname, size_t dlen, 627 uint8_t *constraint, size_t len) 628 { 629 if (len != dlen) 630 return 0; 631 return (memcmp(constraint, dirname, len) == 0); 632 } 633 634 /* 635 * De-obfuscate a GENERAL_NAME into useful bytes for a name or constraint. 636 */ 637 int 638 x509_constraints_general_to_bytes(GENERAL_NAME *name, uint8_t **bytes, 639 size_t *len) 640 { 641 *bytes = NULL; 642 *len = 0; 643 644 if (name->type == GEN_DNS) { 645 ASN1_IA5STRING *aname = name->d.dNSName; 646 *bytes = aname->data; 647 *len = strlen(aname->data); 648 return name->type; 649 } 650 if (name->type == GEN_EMAIL) { 651 ASN1_IA5STRING *aname = name->d.rfc822Name; 652 *bytes = aname->data; 653 *len = strlen(aname->data); 654 return name->type; 655 } 656 if (name->type == GEN_URI) { 657 ASN1_IA5STRING *aname = name->d.uniformResourceIdentifier; 658 *bytes = aname->data; 659 *len = strlen(aname->data); 660 return name->type; 661 } 662 if (name->type == GEN_DIRNAME) { 663 X509_NAME *dname = name->d.directoryName; 664 if (!dname->modified || i2d_X509_NAME(dname, NULL) >= 0) { 665 *bytes = dname->canon_enc; 666 *len = dname->canon_enclen; 667 return name->type; 668 } 669 } 670 if (name->type == GEN_IPADD) { 671 *bytes = name->d.ip->data; 672 *len = name->d.ip->length; 673 return name->type; 674 } 675 return 0; 676 } 677 678 679 /* 680 * Extract the relevant names for constraint checking from "cert", 681 * validate them, and add them to the list of cert names for "chain". 682 * returns 1 on success sets error and returns 0 on failure. 683 */ 684 int 685 x509_constraints_extract_names(struct x509_constraints_names *names, 686 X509 *cert, int is_leaf, int *error) 687 { 688 struct x509_constraints_name *vname = NULL; 689 X509_NAME *subject_name; 690 GENERAL_NAME *name; 691 ssize_t i = 0; 692 int name_type, include_cn = is_leaf, include_email = is_leaf; 693 694 /* first grab the altnames */ 695 while ((name = sk_GENERAL_NAME_value(cert->altname, i++)) != NULL) { 696 uint8_t *bytes = NULL; 697 size_t len = 0; 698 699 if ((vname = x509_constraints_name_new()) == NULL) { 700 *error = X509_V_ERR_OUT_OF_MEM; 701 goto err; 702 } 703 704 name_type = x509_constraints_general_to_bytes(name, &bytes, 705 &len); 706 switch(name_type) { 707 case GEN_DNS: 708 if (!x509_constraints_valid_sandns(bytes, len)) { 709 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 710 goto err; 711 } 712 if ((vname->name = strdup(bytes)) == NULL) { 713 *error = X509_V_ERR_OUT_OF_MEM; 714 goto err; 715 } 716 vname->type = GEN_DNS; 717 include_cn = 0; /* don't use cn from subject */ 718 break; 719 case GEN_EMAIL: 720 if (!x509_constraints_parse_mailbox(bytes, len, 721 vname)) { 722 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 723 goto err; 724 } 725 vname->type = GEN_EMAIL; 726 include_email = 0; /* don't use email from subject */ 727 break; 728 case GEN_URI: 729 if (!x509_constraints_uri_host(bytes, len, &vname->name)) { 730 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 731 goto err; 732 } 733 if (vname->name == NULL) { 734 *error = X509_V_ERR_OUT_OF_MEM; 735 goto err; 736 } 737 vname->type = GEN_URI; 738 break; 739 case GEN_DIRNAME: 740 if (bytes == NULL || ((vname->der = malloc(len)) == 741 NULL)) { 742 *error = X509_V_ERR_OUT_OF_MEM; 743 goto err; 744 } 745 if (len == 0) { 746 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 747 goto err; 748 } 749 memcpy(vname->der, bytes, len); 750 vname->der_len = len; 751 vname->type = GEN_DIRNAME; 752 break; 753 case GEN_IPADD: 754 if (len == 4) 755 vname->af = AF_INET; 756 if (len == 16) 757 vname->af = AF_INET6; 758 if (vname->af != AF_INET && vname->af != 759 AF_INET6) { 760 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 761 goto err; 762 } 763 memcpy(vname->address, bytes, len); 764 vname->type = GEN_IPADD; 765 break; 766 default: 767 /* Ignore this name */ 768 x509_constraints_name_free(vname); 769 vname = NULL; 770 continue; 771 } 772 if (!x509_constraints_names_add(names, vname)) { 773 *error = X509_V_ERR_OUT_OF_MEM; 774 goto err; 775 } 776 vname = NULL; 777 } 778 779 x509_constraints_name_free(vname); 780 vname = NULL; 781 782 subject_name = X509_get_subject_name(cert); 783 if (X509_NAME_entry_count(subject_name) > 0) { 784 X509_NAME_ENTRY *email; 785 X509_NAME_ENTRY *cn; 786 /* 787 * This cert has a non-empty subject, so we must add 788 * the subject as a dirname to be compared against 789 * any dirname constraints 790 */ 791 if ((subject_name->modified && 792 i2d_X509_NAME(subject_name, NULL) < 0) || 793 (vname = x509_constraints_name_new()) == NULL || 794 (vname->der = malloc(subject_name->canon_enclen)) == NULL) { 795 *error = X509_V_ERR_OUT_OF_MEM; 796 goto err; 797 } 798 799 memcpy(vname->der, subject_name->canon_enc, 800 subject_name->canon_enclen); 801 vname->der_len = subject_name->canon_enclen; 802 vname->type = GEN_DIRNAME; 803 if (!x509_constraints_names_add(names, vname)) { 804 *error = X509_V_ERR_OUT_OF_MEM; 805 goto err; 806 } 807 vname = NULL; 808 /* 809 * Get any email addresses from the subject line, and 810 * add them as mbox names to be compared against any 811 * email constraints 812 */ 813 while (include_email && 814 (i = X509_NAME_get_index_by_NID(subject_name, 815 NID_pkcs9_emailAddress, i)) >= 0) { 816 ASN1_STRING *aname; 817 if ((email = X509_NAME_get_entry(subject_name, i)) == NULL || 818 (aname = X509_NAME_ENTRY_get_data(email)) == NULL) { 819 *error = X509_V_ERR_OUT_OF_MEM; 820 goto err; 821 } 822 if ((vname = x509_constraints_name_new()) == NULL) { 823 *error = X509_V_ERR_OUT_OF_MEM; 824 goto err; 825 } 826 if (!x509_constraints_parse_mailbox(aname->data, 827 aname->length, vname)) { 828 *error = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; 829 goto err; 830 } 831 vname->type = GEN_EMAIL; 832 if (!x509_constraints_names_add(names, vname)) { 833 *error = X509_V_ERR_OUT_OF_MEM; 834 goto err; 835 } 836 vname = NULL; 837 } 838 /* 839 * Include the CN as a hostname to be checked againt 840 * name constraints if it looks like a hostname. 841 */ 842 while (include_cn && 843 (i = X509_NAME_get_index_by_NID(subject_name, 844 NID_commonName, i)) >= 0) { 845 ASN1_STRING *aname; 846 if ((cn = X509_NAME_get_entry(subject_name, i)) == NULL || 847 (aname = X509_NAME_ENTRY_get_data(cn)) == NULL) { 848 *error = X509_V_ERR_OUT_OF_MEM; 849 goto err; 850 } 851 if (!x509_constraints_valid_host(aname->data, 852 aname->length)) 853 continue; /* ignore it if not a hostname */ 854 if ((vname = x509_constraints_name_new()) == NULL) { 855 *error = X509_V_ERR_OUT_OF_MEM; 856 goto err; 857 } 858 if ((vname->name = strndup(aname->data, 859 aname->length)) == NULL) { 860 *error = X509_V_ERR_OUT_OF_MEM; 861 goto err; 862 } 863 vname->type = GEN_DNS; 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 return 1; 872 err: 873 x509_constraints_name_free(vname); 874 return 0; 875 } 876 877 /* 878 * Validate a constraint in a general name, putting the relevant data 879 * into "name" if valid. returns 0, and sets error if the constraint is 880 * not valid. returns 1 if the constraint validated. name->type will be 881 * set to a valid type if there is constraint data in name, or unmodified 882 * if the GENERAL_NAME had a valid type but was ignored. 883 */ 884 int 885 x509_constraints_validate(GENERAL_NAME *constraint, 886 struct x509_constraints_name *name, int *error) 887 { 888 uint8_t *bytes = NULL; 889 size_t len = 0; 890 int name_type; 891 892 name_type = x509_constraints_general_to_bytes(constraint, &bytes, &len); 893 switch (name_type) { 894 case GEN_DIRNAME: 895 if (bytes == NULL || (name->der = malloc(len)) == NULL) { 896 *error = X509_V_ERR_OUT_OF_MEM; 897 return 0; 898 } 899 if (len == 0) 900 goto err; /* XXX The RFCs are delightfully vague */ 901 memcpy(name->der, bytes, len); 902 name->der_len = len; 903 name->type = GEN_DIRNAME; 904 break; 905 case GEN_DNS: 906 if (!x509_constraints_valid_domain_constraint(bytes, len)) 907 goto err; 908 if ((name->name = strdup(bytes)) == NULL) { 909 *error = X509_V_ERR_OUT_OF_MEM; 910 return 0; 911 } 912 name->type = GEN_DNS; 913 break; 914 case GEN_EMAIL: 915 if (memchr(bytes, '@', len) != NULL) { 916 if (!x509_constraints_parse_mailbox(bytes, len, name)) 917 goto err; 918 } else { 919 if (!x509_constraints_valid_domain_constraint(bytes, 920 len)) 921 goto err; 922 if ((name->name = strdup(bytes)) == NULL) { 923 *error = X509_V_ERR_OUT_OF_MEM; 924 return 0; 925 } 926 } 927 name->type = GEN_EMAIL; 928 break; 929 case GEN_IPADD: 930 /* Constraints are ip then mask */ 931 if (len == 8) 932 name->af = AF_INET; 933 else if (len == 32) 934 name->af = AF_INET6; 935 else 936 goto err; 937 memcpy(&name->address[0], bytes, len); 938 name->type = GEN_IPADD; 939 break; 940 case GEN_URI: 941 if (!x509_constraints_valid_domain_constraint(bytes, len)) 942 goto err; 943 name->name = strdup(bytes); 944 name->type = GEN_URI; 945 break; 946 default: 947 break; 948 } 949 return 1; 950 err: 951 *error = X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX; 952 return 0; 953 } 954 955 int 956 x509_constraints_extract_constraints(X509 *cert, 957 struct x509_constraints_names *permitted, 958 struct x509_constraints_names *excluded, 959 int *error) 960 { 961 struct x509_constraints_name *vname; 962 NAME_CONSTRAINTS *nc = cert->nc; 963 GENERAL_SUBTREE *subtree; 964 int i; 965 966 if (nc == NULL) 967 return 1; 968 969 for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) { 970 971 subtree = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i); 972 if (subtree->minimum || subtree->maximum) { 973 *error = X509_V_ERR_SUBTREE_MINMAX; 974 return 0; 975 } 976 if ((vname = x509_constraints_name_new()) == NULL) { 977 *error = X509_V_ERR_OUT_OF_MEM; 978 return 0; 979 } 980 if (x509_constraints_validate(subtree->base, vname, error) == 981 0) { 982 x509_constraints_name_free(vname); 983 return 0; 984 } 985 if (vname->type == 0) { 986 x509_constraints_name_free(vname); 987 continue; 988 } 989 if (!x509_constraints_names_add(permitted, vname)) { 990 x509_constraints_name_free(vname); 991 *error = X509_V_ERR_OUT_OF_MEM; 992 return 0; 993 } 994 } 995 996 for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) { 997 subtree = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i); 998 if (subtree->minimum || subtree->maximum) { 999 *error = X509_V_ERR_SUBTREE_MINMAX; 1000 return 0; 1001 } 1002 if ((vname = x509_constraints_name_new()) == NULL) { 1003 *error = X509_V_ERR_OUT_OF_MEM; 1004 return 0; 1005 } 1006 if (x509_constraints_validate(subtree->base, vname, error) == 1007 0) { 1008 x509_constraints_name_free(vname); 1009 return 0; 1010 } 1011 if (vname->type == 0) { 1012 x509_constraints_name_free(vname); 1013 continue; 1014 } 1015 if (!x509_constraints_names_add(excluded, vname)) { 1016 x509_constraints_name_free(vname); 1017 *error = X509_V_ERR_OUT_OF_MEM; 1018 return 0; 1019 } 1020 } 1021 1022 return 1; 1023 } 1024 1025 /* 1026 * Match a validated name in "name" against a validated constraint in 1027 * "constraint" return 1 if then name matches, 0 otherwise. 1028 */ 1029 int 1030 x509_constraints_match(struct x509_constraints_name *name, 1031 struct x509_constraints_name *constraint) 1032 { 1033 if (name->type != constraint->type) 1034 return 0; 1035 if (name->type == GEN_DNS) 1036 return x509_constraints_sandns(name->name, strlen(name->name), 1037 constraint->name, strlen(constraint->name)); 1038 if (name->type == GEN_URI) 1039 return x509_constraints_domain(name->name, strlen(name->name), 1040 constraint->name, strlen(constraint->name)); 1041 if (name->type == GEN_IPADD) { 1042 size_t nlen = name->af == AF_INET ? 4 : 16; 1043 size_t clen = name->af == AF_INET ? 8 : 32; 1044 if (name->af != AF_INET && name->af != AF_INET6) 1045 return 0; 1046 if (constraint->af != AF_INET && constraint->af != AF_INET6) 1047 return 0; 1048 if (name->af != constraint->af) 1049 return 0; 1050 return x509_constraints_ipaddr(name->address, nlen, 1051 constraint->address, clen); 1052 } 1053 if (name->type == GEN_EMAIL) { 1054 if (constraint->local) { 1055 /* mailbox local and domain parts must exactly match */ 1056 return (strcmp(name->local, constraint->local) == 0 && 1057 strcmp(name->name, constraint->name) == 0); 1058 } 1059 /* otherwise match the constraint to the domain part */ 1060 return x509_constraints_domain(name->name, strlen(name->name), 1061 constraint->name, strlen(constraint->name)); 1062 } 1063 if (name->type == GEN_DIRNAME) 1064 return x509_constraints_dirname(name->der, name->der_len, 1065 constraint->der, constraint->der_len); 1066 return 0; 1067 } 1068 1069 /* 1070 * Make sure every name in names does not match any excluded 1071 * constraints, and does match at least one permitted constraint if 1072 * any are present. Returns 1 if ok, 0, and sets error if not. 1073 */ 1074 int 1075 x509_constraints_check(struct x509_constraints_names *names, 1076 struct x509_constraints_names *permitted, 1077 struct x509_constraints_names *excluded, int *error) 1078 { 1079 size_t i, j; 1080 1081 for (i = 0; i < names->names_count; i++) { 1082 int permitted_seen = 0; 1083 int permitted_matched = 0; 1084 1085 for (j = 0; j < excluded->names_count; j++) { 1086 if (x509_constraints_match(names->names[i], 1087 excluded->names[j])) { 1088 *error = X509_V_ERR_EXCLUDED_VIOLATION; 1089 return 0; 1090 } 1091 } 1092 for (j = 0; j < permitted->names_count; j++) { 1093 if (permitted->names[j]->type == names->names[i]->type) 1094 permitted_seen++; 1095 if (x509_constraints_match(names->names[i], 1096 permitted->names[j])) { 1097 permitted_matched++; 1098 break; 1099 } 1100 } 1101 if (permitted_seen && !permitted_matched) { 1102 *error = X509_V_ERR_PERMITTED_VIOLATION; 1103 return 0; 1104 } 1105 } 1106 return 1; 1107 } 1108 1109 /* 1110 * Walk a validated chain of X509 certs, starting at the leaf, and 1111 * validate the name constraints in the chain. Intended for use with 1112 * the legacy X509 validtion code in x509_vfy.c 1113 * 1114 * returns 1 if the constraints are ok, 0 otherwise, setting error and 1115 * depth 1116 */ 1117 int 1118 x509_constraints_chain(STACK_OF(X509) *chain, int *error, int *depth) 1119 { 1120 int chain_length, verify_err = X509_V_ERR_UNSPECIFIED, i = 0; 1121 struct x509_constraints_names *names = NULL; 1122 struct x509_constraints_names *excluded = NULL; 1123 struct x509_constraints_names *permitted = NULL; 1124 size_t constraints_count = 0; 1125 X509 *cert; 1126 1127 if (chain == NULL || (chain_length = sk_X509_num(chain)) == 0) 1128 goto err; 1129 if (chain_length == 1) 1130 return 1; 1131 if ((names = x509_constraints_names_new( 1132 X509_VERIFY_MAX_CHAIN_NAMES)) == NULL) { 1133 verify_err = X509_V_ERR_OUT_OF_MEM; 1134 goto err; 1135 } 1136 1137 if ((cert = sk_X509_value(chain, 0)) == NULL) 1138 goto err; 1139 if (!x509_constraints_extract_names(names, cert, 1, &verify_err)) 1140 goto err; 1141 for (i = 1; i < chain_length; i++) { 1142 if ((cert = sk_X509_value(chain, i)) == NULL) 1143 goto err; 1144 if (cert->nc != NULL) { 1145 if ((permitted = x509_constraints_names_new( 1146 X509_VERIFY_MAX_CHAIN_CONSTRAINTS)) == NULL) { 1147 verify_err = X509_V_ERR_OUT_OF_MEM; 1148 goto err; 1149 } 1150 if ((excluded = x509_constraints_names_new( 1151 X509_VERIFY_MAX_CHAIN_CONSTRAINTS)) == NULL) { 1152 verify_err = X509_V_ERR_OUT_OF_MEM; 1153 goto err; 1154 } 1155 if (!x509_constraints_extract_constraints(cert, 1156 permitted, excluded, &verify_err)) 1157 goto err; 1158 constraints_count += permitted->names_count; 1159 constraints_count += excluded->names_count; 1160 if (constraints_count > 1161 X509_VERIFY_MAX_CHAIN_CONSTRAINTS) { 1162 verify_err = X509_V_ERR_OUT_OF_MEM; 1163 goto err; 1164 } 1165 if (!x509_constraints_check(names, permitted, excluded, 1166 &verify_err)) 1167 goto err; 1168 x509_constraints_names_free(excluded); 1169 excluded = NULL; 1170 x509_constraints_names_free(permitted); 1171 permitted = NULL; 1172 } 1173 if (!x509_constraints_extract_names(names, cert, 0, 1174 &verify_err)) 1175 goto err; 1176 } 1177 1178 x509_constraints_names_free(names); 1179 return 1; 1180 1181 err: 1182 *error = verify_err; 1183 *depth = i; 1184 x509_constraints_names_free(excluded); 1185 x509_constraints_names_free(permitted); 1186 x509_constraints_names_free(names); 1187 return 0; 1188 } 1189