1 /* $OpenBSD: x509_purp.c,v 1.2 2020/09/13 15:06:17 beck Exp $ */ 2 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL 3 * project 2001. 4 */ 5 /* ==================================================================== 6 * Copyright (c) 1999-2004 The OpenSSL Project. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 20 * 3. All advertising materials mentioning features or use of this 21 * software must display the following acknowledgment: 22 * "This product includes software developed by the OpenSSL Project 23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" 24 * 25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 26 * endorse or promote products derived from this software without 27 * prior written permission. For written permission, please contact 28 * licensing@OpenSSL.org. 29 * 30 * 5. Products derived from this software may not be called "OpenSSL" 31 * nor may "OpenSSL" appear in their names without prior written 32 * permission of the OpenSSL Project. 33 * 34 * 6. Redistributions of any form whatsoever must retain the following 35 * acknowledgment: 36 * "This product includes software developed by the OpenSSL Project 37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" 38 * 39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 50 * OF THE POSSIBILITY OF SUCH DAMAGE. 51 * ==================================================================== 52 * 53 * This product includes cryptographic software written by Eric Young 54 * (eay@cryptsoft.com). This product includes software written by Tim 55 * Hudson (tjh@cryptsoft.com). 56 * 57 */ 58 59 #include <stdio.h> 60 #include <string.h> 61 62 #include <openssl/opensslconf.h> 63 64 #include <openssl/err.h> 65 #include <openssl/x509v3.h> 66 #include <openssl/x509_vfy.h> 67 68 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS) 69 #define ku_reject(x, usage) \ 70 (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage))) 71 #define xku_reject(x, usage) \ 72 (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage))) 73 #define ns_reject(x, usage) \ 74 (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage))) 75 76 void x509v3_cache_extensions(X509 *x); 77 78 static int check_ssl_ca(const X509 *x); 79 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, 80 int ca); 81 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, 82 int ca); 83 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, 84 int ca); 85 static int purpose_smime(const X509 *x, int ca); 86 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, 87 int ca); 88 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, 89 int ca); 90 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, 91 int ca); 92 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x, 93 int ca); 94 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca); 95 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca); 96 97 static int xp_cmp(const X509_PURPOSE * const *a, const X509_PURPOSE * const *b); 98 static void xptable_free(X509_PURPOSE *p); 99 100 static X509_PURPOSE xstandard[] = { 101 {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0, check_purpose_ssl_client, "SSL client", "sslclient", NULL}, 102 {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ssl_server, "SSL server", "sslserver", NULL}, 103 {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL}, 104 {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign, "S/MIME signing", "smimesign", NULL}, 105 {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0, check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL}, 106 {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign, "CRL signing", "crlsign", NULL}, 107 {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any", NULL}, 108 {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper, "OCSP helper", "ocsphelper", NULL}, 109 {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0, check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign", NULL}, 110 }; 111 112 #define X509_PURPOSE_COUNT (sizeof(xstandard)/sizeof(X509_PURPOSE)) 113 114 static STACK_OF(X509_PURPOSE) *xptable = NULL; 115 116 static int 117 xp_cmp(const X509_PURPOSE * const *a, const X509_PURPOSE * const *b) 118 { 119 return (*a)->purpose - (*b)->purpose; 120 } 121 122 /* As much as I'd like to make X509_check_purpose use a "const" X509* 123 * I really can't because it does recalculate hashes and do other non-const 124 * things. */ 125 int 126 X509_check_purpose(X509 *x, int id, int ca) 127 { 128 int idx; 129 const X509_PURPOSE *pt; 130 131 if (!(x->ex_flags & EXFLAG_SET)) { 132 CRYPTO_w_lock(CRYPTO_LOCK_X509); 133 x509v3_cache_extensions(x); 134 CRYPTO_w_unlock(CRYPTO_LOCK_X509); 135 } 136 if (id == -1) 137 return 1; 138 idx = X509_PURPOSE_get_by_id(id); 139 if (idx == -1) 140 return -1; 141 pt = X509_PURPOSE_get0(idx); 142 return pt->check_purpose(pt, x, ca); 143 } 144 145 int 146 X509_PURPOSE_set(int *p, int purpose) 147 { 148 if (X509_PURPOSE_get_by_id(purpose) == -1) { 149 X509V3error(X509V3_R_INVALID_PURPOSE); 150 return 0; 151 } 152 *p = purpose; 153 return 1; 154 } 155 156 int 157 X509_PURPOSE_get_count(void) 158 { 159 if (!xptable) 160 return X509_PURPOSE_COUNT; 161 return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT; 162 } 163 164 X509_PURPOSE * 165 X509_PURPOSE_get0(int idx) 166 { 167 if (idx < 0) 168 return NULL; 169 if (idx < (int)X509_PURPOSE_COUNT) 170 return xstandard + idx; 171 return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT); 172 } 173 174 int 175 X509_PURPOSE_get_by_sname(const char *sname) 176 { 177 int i; 178 X509_PURPOSE *xptmp; 179 180 for (i = 0; i < X509_PURPOSE_get_count(); i++) { 181 xptmp = X509_PURPOSE_get0(i); 182 if (!strcmp(xptmp->sname, sname)) 183 return i; 184 } 185 return -1; 186 } 187 188 int 189 X509_PURPOSE_get_by_id(int purpose) 190 { 191 X509_PURPOSE tmp; 192 int idx; 193 194 if ((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX)) 195 return purpose - X509_PURPOSE_MIN; 196 tmp.purpose = purpose; 197 if (!xptable) 198 return -1; 199 idx = sk_X509_PURPOSE_find(xptable, &tmp); 200 if (idx == -1) 201 return -1; 202 return idx + X509_PURPOSE_COUNT; 203 } 204 205 int 206 X509_PURPOSE_add(int id, int trust, int flags, 207 int (*ck)(const X509_PURPOSE *, const X509 *, int), const char *name, 208 const char *sname, void *arg) 209 { 210 int idx; 211 X509_PURPOSE *ptmp; 212 char *name_dup, *sname_dup; 213 214 name_dup = sname_dup = NULL; 215 216 if (name == NULL || sname == NULL) { 217 X509V3error(X509V3_R_INVALID_NULL_ARGUMENT); 218 return 0; 219 } 220 221 /* This is set according to what we change: application can't set it */ 222 flags &= ~X509_PURPOSE_DYNAMIC; 223 /* This will always be set for application modified trust entries */ 224 flags |= X509_PURPOSE_DYNAMIC_NAME; 225 /* Get existing entry if any */ 226 idx = X509_PURPOSE_get_by_id(id); 227 /* Need a new entry */ 228 if (idx == -1) { 229 if ((ptmp = malloc(sizeof(X509_PURPOSE))) == NULL) { 230 X509V3error(ERR_R_MALLOC_FAILURE); 231 return 0; 232 } 233 ptmp->flags = X509_PURPOSE_DYNAMIC; 234 } else 235 ptmp = X509_PURPOSE_get0(idx); 236 237 if ((name_dup = strdup(name)) == NULL) 238 goto err; 239 if ((sname_dup = strdup(sname)) == NULL) 240 goto err; 241 242 /* free existing name if dynamic */ 243 if (ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) { 244 free(ptmp->name); 245 free(ptmp->sname); 246 } 247 /* dup supplied name */ 248 ptmp->name = name_dup; 249 ptmp->sname = sname_dup; 250 /* Keep the dynamic flag of existing entry */ 251 ptmp->flags &= X509_PURPOSE_DYNAMIC; 252 /* Set all other flags */ 253 ptmp->flags |= flags; 254 255 ptmp->purpose = id; 256 ptmp->trust = trust; 257 ptmp->check_purpose = ck; 258 ptmp->usr_data = arg; 259 260 /* If its a new entry manage the dynamic table */ 261 if (idx == -1) { 262 if (xptable == NULL && 263 (xptable = sk_X509_PURPOSE_new(xp_cmp)) == NULL) 264 goto err; 265 if (sk_X509_PURPOSE_push(xptable, ptmp) == 0) 266 goto err; 267 } 268 return 1; 269 270 err: 271 free(name_dup); 272 free(sname_dup); 273 if (idx == -1) 274 free(ptmp); 275 X509V3error(ERR_R_MALLOC_FAILURE); 276 return 0; 277 } 278 279 static void 280 xptable_free(X509_PURPOSE *p) 281 { 282 if (!p) 283 return; 284 if (p->flags & X509_PURPOSE_DYNAMIC) { 285 if (p->flags & X509_PURPOSE_DYNAMIC_NAME) { 286 free(p->name); 287 free(p->sname); 288 } 289 free(p); 290 } 291 } 292 293 void 294 X509_PURPOSE_cleanup(void) 295 { 296 unsigned int i; 297 298 sk_X509_PURPOSE_pop_free(xptable, xptable_free); 299 for(i = 0; i < X509_PURPOSE_COUNT; i++) 300 xptable_free(xstandard + i); 301 xptable = NULL; 302 } 303 304 int 305 X509_PURPOSE_get_id(const X509_PURPOSE *xp) 306 { 307 return xp->purpose; 308 } 309 310 char * 311 X509_PURPOSE_get0_name(const X509_PURPOSE *xp) 312 { 313 return xp->name; 314 } 315 316 char * 317 X509_PURPOSE_get0_sname(const X509_PURPOSE *xp) 318 { 319 return xp->sname; 320 } 321 322 int 323 X509_PURPOSE_get_trust(const X509_PURPOSE *xp) 324 { 325 return xp->trust; 326 } 327 328 static int 329 nid_cmp(const int *a, const int *b) 330 { 331 return *a - *b; 332 } 333 334 static int nid_cmp_BSEARCH_CMP_FN(const void *, const void *); 335 static int nid_cmp(int const *, int const *); 336 static int *OBJ_bsearch_nid(int *key, int const *base, int num); 337 338 static int 339 nid_cmp_BSEARCH_CMP_FN(const void *a_, const void *b_) 340 { 341 int const *a = a_; 342 int const *b = b_; 343 return nid_cmp(a, b); 344 } 345 346 static int * 347 OBJ_bsearch_nid(int *key, int const *base, int num) 348 { 349 return (int *)OBJ_bsearch_(key, base, num, sizeof(int), 350 nid_cmp_BSEARCH_CMP_FN); 351 } 352 353 int 354 X509_supported_extension(X509_EXTENSION *ex) 355 { 356 /* This table is a list of the NIDs of supported extensions: 357 * that is those which are used by the verify process. If 358 * an extension is critical and doesn't appear in this list 359 * then the verify process will normally reject the certificate. 360 * The list must be kept in numerical order because it will be 361 * searched using bsearch. 362 */ 363 364 static const int supported_nids[] = { 365 NID_netscape_cert_type, /* 71 */ 366 NID_key_usage, /* 83 */ 367 NID_subject_alt_name, /* 85 */ 368 NID_basic_constraints, /* 87 */ 369 NID_certificate_policies, /* 89 */ 370 NID_ext_key_usage, /* 126 */ 371 NID_policy_constraints, /* 401 */ 372 NID_proxyCertInfo, /* 663 */ 373 NID_name_constraints, /* 666 */ 374 NID_policy_mappings, /* 747 */ 375 NID_inhibit_any_policy /* 748 */ 376 }; 377 378 int ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex)); 379 380 if (ex_nid == NID_undef) 381 return 0; 382 383 if (OBJ_bsearch_nid(&ex_nid, supported_nids, 384 sizeof(supported_nids) / sizeof(int))) 385 return 1; 386 return 0; 387 } 388 389 static void 390 setup_dp(X509 *x, DIST_POINT *dp) 391 { 392 X509_NAME *iname = NULL; 393 int i; 394 395 if (dp->reasons) { 396 if (dp->reasons->length > 0) 397 dp->dp_reasons = dp->reasons->data[0]; 398 if (dp->reasons->length > 1) 399 dp->dp_reasons |= (dp->reasons->data[1] << 8); 400 dp->dp_reasons &= CRLDP_ALL_REASONS; 401 } else 402 dp->dp_reasons = CRLDP_ALL_REASONS; 403 if (!dp->distpoint || (dp->distpoint->type != 1)) 404 return; 405 for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) { 406 GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i); 407 if (gen->type == GEN_DIRNAME) { 408 iname = gen->d.directoryName; 409 break; 410 } 411 } 412 if (!iname) 413 iname = X509_get_issuer_name(x); 414 415 DIST_POINT_set_dpname(dp->distpoint, iname); 416 417 } 418 419 static void 420 setup_crldp(X509 *x) 421 { 422 int i; 423 424 x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL); 425 for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) 426 setup_dp(x, sk_DIST_POINT_value(x->crldp, i)); 427 } 428 429 void 430 x509v3_cache_extensions(X509 *x) 431 { 432 BASIC_CONSTRAINTS *bs; 433 PROXY_CERT_INFO_EXTENSION *pci; 434 ASN1_BIT_STRING *usage; 435 ASN1_BIT_STRING *ns; 436 EXTENDED_KEY_USAGE *extusage; 437 X509_EXTENSION *ex; 438 int i; 439 440 if (x->ex_flags & EXFLAG_SET) 441 return; 442 443 #ifndef OPENSSL_NO_SHA 444 X509_digest(x, EVP_sha1(), x->sha1_hash, NULL); 445 #endif 446 447 /* V1 should mean no extensions ... */ 448 if (!X509_get_version(x)) 449 x->ex_flags |= EXFLAG_V1; 450 451 /* Handle basic constraints */ 452 if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) { 453 if (bs->ca) 454 x->ex_flags |= EXFLAG_CA; 455 if (bs->pathlen) { 456 if ((bs->pathlen->type == V_ASN1_NEG_INTEGER) || 457 !bs->ca) { 458 x->ex_flags |= EXFLAG_INVALID; 459 x->ex_pathlen = 0; 460 } else 461 x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen); 462 } else 463 x->ex_pathlen = -1; 464 BASIC_CONSTRAINTS_free(bs); 465 x->ex_flags |= EXFLAG_BCONS; 466 } 467 468 /* Handle proxy certificates */ 469 if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) { 470 if (x->ex_flags & EXFLAG_CA || 471 X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0 || 472 X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) { 473 x->ex_flags |= EXFLAG_INVALID; 474 } 475 if (pci->pcPathLengthConstraint) { 476 if (pci->pcPathLengthConstraint->type == 477 V_ASN1_NEG_INTEGER) { 478 x->ex_flags |= EXFLAG_INVALID; 479 x->ex_pcpathlen = 0; 480 } else 481 x->ex_pcpathlen = 482 ASN1_INTEGER_get(pci-> 483 pcPathLengthConstraint); 484 } else 485 x->ex_pcpathlen = -1; 486 PROXY_CERT_INFO_EXTENSION_free(pci); 487 x->ex_flags |= EXFLAG_PROXY; 488 } 489 490 /* Handle key usage */ 491 if ((usage = X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) { 492 if (usage->length > 0) { 493 x->ex_kusage = usage->data[0]; 494 if (usage->length > 1) 495 x->ex_kusage |= usage->data[1] << 8; 496 } else 497 x->ex_kusage = 0; 498 x->ex_flags |= EXFLAG_KUSAGE; 499 ASN1_BIT_STRING_free(usage); 500 } 501 x->ex_xkusage = 0; 502 if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) { 503 x->ex_flags |= EXFLAG_XKUSAGE; 504 for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) { 505 switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) { 506 case NID_server_auth: 507 x->ex_xkusage |= XKU_SSL_SERVER; 508 break; 509 510 case NID_client_auth: 511 x->ex_xkusage |= XKU_SSL_CLIENT; 512 break; 513 514 case NID_email_protect: 515 x->ex_xkusage |= XKU_SMIME; 516 break; 517 518 case NID_code_sign: 519 x->ex_xkusage |= XKU_CODE_SIGN; 520 break; 521 522 case NID_ms_sgc: 523 case NID_ns_sgc: 524 x->ex_xkusage |= XKU_SGC; 525 break; 526 527 case NID_OCSP_sign: 528 x->ex_xkusage |= XKU_OCSP_SIGN; 529 break; 530 531 case NID_time_stamp: 532 x->ex_xkusage |= XKU_TIMESTAMP; 533 break; 534 535 case NID_dvcs: 536 x->ex_xkusage |= XKU_DVCS; 537 break; 538 } 539 } 540 sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free); 541 } 542 543 if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) { 544 if (ns->length > 0) 545 x->ex_nscert = ns->data[0]; 546 else 547 x->ex_nscert = 0; 548 x->ex_flags |= EXFLAG_NSCERT; 549 ASN1_BIT_STRING_free(ns); 550 } 551 552 x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL); 553 x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL); 554 555 /* Does subject name match issuer? */ 556 if (!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x))) { 557 x->ex_flags |= EXFLAG_SI; 558 /* If SKID matches AKID also indicate self signed. */ 559 if (X509_check_akid(x, x->akid) == X509_V_OK && 560 !ku_reject(x, KU_KEY_CERT_SIGN)) 561 x->ex_flags |= EXFLAG_SS; 562 } 563 564 x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL); 565 x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL); 566 if (!x->nc && (i != -1)) 567 x->ex_flags |= EXFLAG_INVALID; 568 setup_crldp(x); 569 570 for (i = 0; i < X509_get_ext_count(x); i++) { 571 ex = X509_get_ext(x, i); 572 if (OBJ_obj2nid(X509_EXTENSION_get_object(ex)) == 573 NID_freshest_crl) 574 x->ex_flags |= EXFLAG_FRESHEST; 575 if (!X509_EXTENSION_get_critical(ex)) 576 continue; 577 if (!X509_supported_extension(ex)) { 578 x->ex_flags |= EXFLAG_CRITICAL; 579 break; 580 } 581 } 582 x->ex_flags |= EXFLAG_SET; 583 } 584 585 /* CA checks common to all purposes 586 * return codes: 587 * 0 not a CA 588 * 1 is a CA 589 * 2 basicConstraints absent so "maybe" a CA 590 * 3 basicConstraints absent but self signed V1. 591 * 4 basicConstraints absent but keyUsage present and keyCertSign asserted. 592 */ 593 594 static int 595 check_ca(const X509 *x) 596 { 597 /* keyUsage if present should allow cert signing */ 598 if (ku_reject(x, KU_KEY_CERT_SIGN)) 599 return 0; 600 if (x->ex_flags & EXFLAG_BCONS) { 601 if (x->ex_flags & EXFLAG_CA) 602 return 1; 603 /* If basicConstraints says not a CA then say so */ 604 else 605 return 0; 606 } else { 607 /* we support V1 roots for... uh, I don't really know why. */ 608 if ((x->ex_flags & V1_ROOT) == V1_ROOT) 609 return 3; 610 /* If key usage present it must have certSign so tolerate it */ 611 else if (x->ex_flags & EXFLAG_KUSAGE) 612 return 4; 613 /* Older certificates could have Netscape-specific CA types */ 614 else if (x->ex_flags & EXFLAG_NSCERT && 615 x->ex_nscert & NS_ANY_CA) 616 return 5; 617 /* can this still be regarded a CA certificate? I doubt it */ 618 return 0; 619 } 620 } 621 622 int 623 X509_check_ca(X509 *x) 624 { 625 if (!(x->ex_flags & EXFLAG_SET)) { 626 CRYPTO_w_lock(CRYPTO_LOCK_X509); 627 x509v3_cache_extensions(x); 628 CRYPTO_w_unlock(CRYPTO_LOCK_X509); 629 } 630 631 return check_ca(x); 632 } 633 634 /* Check SSL CA: common checks for SSL client and server */ 635 static int 636 check_ssl_ca(const X509 *x) 637 { 638 int ca_ret; 639 640 ca_ret = check_ca(x); 641 if (!ca_ret) 642 return 0; 643 /* check nsCertType if present */ 644 if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA) 645 return ca_ret; 646 else 647 return 0; 648 } 649 650 static int 651 check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca) 652 { 653 if (xku_reject(x, XKU_SSL_CLIENT)) 654 return 0; 655 if (ca) 656 return check_ssl_ca(x); 657 /* We need to do digital signatures with it */ 658 if (ku_reject(x, KU_DIGITAL_SIGNATURE)) 659 return 0; 660 /* nsCertType if present should allow SSL client use */ 661 if (ns_reject(x, NS_SSL_CLIENT)) 662 return 0; 663 return 1; 664 } 665 666 static int 667 check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca) 668 { 669 if (xku_reject(x, XKU_SSL_SERVER|XKU_SGC)) 670 return 0; 671 if (ca) 672 return check_ssl_ca(x); 673 674 if (ns_reject(x, NS_SSL_SERVER)) 675 return 0; 676 /* Now as for keyUsage: we'll at least need to sign OR encipher */ 677 if (ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) 678 return 0; 679 680 return 1; 681 } 682 683 static int 684 check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca) 685 { 686 int ret; 687 688 ret = check_purpose_ssl_server(xp, x, ca); 689 if (!ret || ca) 690 return ret; 691 /* We need to encipher or Netscape complains */ 692 if (ku_reject(x, KU_KEY_ENCIPHERMENT)) 693 return 0; 694 return ret; 695 } 696 697 /* common S/MIME checks */ 698 static int 699 purpose_smime(const X509 *x, int ca) 700 { 701 if (xku_reject(x, XKU_SMIME)) 702 return 0; 703 if (ca) { 704 int ca_ret; 705 ca_ret = check_ca(x); 706 if (!ca_ret) 707 return 0; 708 /* check nsCertType if present */ 709 if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA) 710 return ca_ret; 711 else 712 return 0; 713 } 714 if (x->ex_flags & EXFLAG_NSCERT) { 715 if (x->ex_nscert & NS_SMIME) 716 return 1; 717 /* Workaround for some buggy certificates */ 718 if (x->ex_nscert & NS_SSL_CLIENT) 719 return 2; 720 return 0; 721 } 722 return 1; 723 } 724 725 static int 726 check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca) 727 { 728 int ret; 729 730 ret = purpose_smime(x, ca); 731 if (!ret || ca) 732 return ret; 733 if (ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) 734 return 0; 735 return ret; 736 } 737 738 static int 739 check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca) 740 { 741 int ret; 742 743 ret = purpose_smime(x, ca); 744 if (!ret || ca) 745 return ret; 746 if (ku_reject(x, KU_KEY_ENCIPHERMENT)) 747 return 0; 748 return ret; 749 } 750 751 static int 752 check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca) 753 { 754 if (ca) { 755 int ca_ret; 756 if ((ca_ret = check_ca(x)) != 2) 757 return ca_ret; 758 else 759 return 0; 760 } 761 if (ku_reject(x, KU_CRL_SIGN)) 762 return 0; 763 return 1; 764 } 765 766 /* OCSP helper: this is *not* a full OCSP check. It just checks that 767 * each CA is valid. Additional checks must be made on the chain. 768 */ 769 static int 770 ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca) 771 { 772 /* Must be a valid CA. Should we really support the "I don't know" 773 value (2)? */ 774 if (ca) 775 return check_ca(x); 776 /* leaf certificate is checked in OCSP_verify() */ 777 return 1; 778 } 779 780 static int 781 check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x, int ca) 782 { 783 int i_ext; 784 785 /* If ca is true we must return if this is a valid CA certificate. */ 786 if (ca) 787 return check_ca(x); 788 789 /* 790 * Check the optional key usage field: 791 * if Key Usage is present, it must be one of digitalSignature 792 * and/or nonRepudiation (other values are not consistent and shall 793 * be rejected). 794 */ 795 if ((x->ex_flags & EXFLAG_KUSAGE) && 796 ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) || 797 !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)))) 798 return 0; 799 800 /* Only time stamp key usage is permitted and it's required. */ 801 if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP) 802 return 0; 803 804 /* Extended Key Usage MUST be critical */ 805 i_ext = X509_get_ext_by_NID((X509 *) x, NID_ext_key_usage, -1); 806 if (i_ext >= 0) { 807 X509_EXTENSION *ext = X509_get_ext((X509 *) x, i_ext); 808 if (!X509_EXTENSION_get_critical(ext)) 809 return 0; 810 } 811 812 return 1; 813 } 814 815 static int 816 no_check(const X509_PURPOSE *xp, const X509 *x, int ca) 817 { 818 return 1; 819 } 820 821 /* Various checks to see if one certificate issued the second. 822 * This can be used to prune a set of possible issuer certificates 823 * which have been looked up using some simple method such as by 824 * subject name. 825 * These are: 826 * 1. Check issuer_name(subject) == subject_name(issuer) 827 * 2. If akid(subject) exists check it matches issuer 828 * 3. If key_usage(issuer) exists check it supports certificate signing 829 * returns 0 for OK, positive for reason for mismatch, reasons match 830 * codes for X509_verify_cert() 831 */ 832 833 int 834 X509_check_issued(X509 *issuer, X509 *subject) 835 { 836 if (X509_NAME_cmp(X509_get_subject_name(issuer), 837 X509_get_issuer_name(subject))) 838 return X509_V_ERR_SUBJECT_ISSUER_MISMATCH; 839 x509v3_cache_extensions(issuer); 840 x509v3_cache_extensions(subject); 841 842 if (subject->akid) { 843 int ret = X509_check_akid(issuer, subject->akid); 844 if (ret != X509_V_OK) 845 return ret; 846 } 847 848 if (subject->ex_flags & EXFLAG_PROXY) { 849 if (ku_reject(issuer, KU_DIGITAL_SIGNATURE)) 850 return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE; 851 } else if (ku_reject(issuer, KU_KEY_CERT_SIGN)) 852 return X509_V_ERR_KEYUSAGE_NO_CERTSIGN; 853 return X509_V_OK; 854 } 855 856 int 857 X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid) 858 { 859 if (!akid) 860 return X509_V_OK; 861 862 /* Check key ids (if present) */ 863 if (akid->keyid && issuer->skid && 864 ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid) ) 865 return X509_V_ERR_AKID_SKID_MISMATCH; 866 /* Check serial number */ 867 if (akid->serial && 868 ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial)) 869 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH; 870 /* Check issuer name */ 871 if (akid->issuer) { 872 /* Ugh, for some peculiar reason AKID includes 873 * SEQUENCE OF GeneralName. So look for a DirName. 874 * There may be more than one but we only take any 875 * notice of the first. 876 */ 877 GENERAL_NAMES *gens; 878 GENERAL_NAME *gen; 879 X509_NAME *nm = NULL; 880 int i; 881 gens = akid->issuer; 882 for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) { 883 gen = sk_GENERAL_NAME_value(gens, i); 884 if (gen->type == GEN_DIRNAME) { 885 nm = gen->d.dirn; 886 break; 887 } 888 } 889 if (nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer))) 890 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH; 891 } 892 return X509_V_OK; 893 } 894