crypto/x509v3/v3_purp.c

   1 /* v3_purp.c */
   2 /* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL
   3  * project 1999.
   4  */
   5 /* ====================================================================
   6  * Copyright (c) 1999 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 "cryptlib.h"
  61 #include <openssl/x509v3.h>
  62 #include <openssl/x509_vfy.h>
  63
  64 static void x509v3_cache_extensions(X509 *x);
  65
  66 static int ca_check(const X509 *x);
  67 static int check_ssl_ca(const X509 *x);
  68 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca);
  69 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
  70 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
  71 static int purpose_smime(const X509 *x, int ca);
  72 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
  73 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca);
  74 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
  75 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
  76 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
  77
  78 static int xp_cmp(const X509_PURPOSE * const *a,
  79                 const X509_PURPOSE * const *b);
  80 static void xptable_free(X509_PURPOSE *p);
  81
  82 static X509_PURPOSE xstandard[] = {
  83         {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0, check_purpose_ssl_client, "SSL client", "sslclient", NULL},
  84         {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ssl_server, "SSL server", "sslserver", NULL},
  85         {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
  86         {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign, "S/MIME signing", "smimesign", NULL},
  87         {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0, check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
  88         {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign, "CRL signing", "crlsign", NULL},
  89         {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any", NULL},
  90         {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper, "OCSP helper", "ocsphelper", NULL},
  91 };
  92
  93 #define X509_PURPOSE_COUNT (sizeof(xstandard)/sizeof(X509_PURPOSE))
  94
  95 IMPLEMENT_STACK_OF(X509_PURPOSE)
  96
  97 static STACK_OF(X509_PURPOSE) *xptable = NULL;
  98
  99 static int xp_cmp(const X509_PURPOSE * const *a,
 100                 const X509_PURPOSE * const *b)
 101 {
 102         return (*a)->purpose - (*b)->purpose;
 103 }
 104
 105 /* As much as I'd like to make X509_check_purpose use a "const" X509*
 106  * I really can't because it does recalculate hashes and do other non-const
 107  * things. */
 108 int X509_check_purpose(X509 *x, int id, int ca)
 109 {
 110         int idx;
 111         const X509_PURPOSE *pt;
 112         if(!(x->ex_flags & EXFLAG_SET)) {
 113                 CRYPTO_w_lock(CRYPTO_LOCK_X509);
 114                 x509v3_cache_extensions(x);
 115                 CRYPTO_w_unlock(CRYPTO_LOCK_X509);
 116         }
 117         if(id == -1) return 1;
 118         idx = X509_PURPOSE_get_by_id(id);
 119         if(idx == -1) return -1;
 120         pt = X509_PURPOSE_get0(idx);
 121         return pt->check_purpose(pt, x, ca);
 122 }
 123
 124 int X509_PURPOSE_set(int *p, int purpose)
 125 {
 126         if(X509_PURPOSE_get_by_id(purpose) == -1) {
 127                 X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
 128                 return 0;
 129         }
 130         *p = purpose;
 131         return 1;
 132 }
 133
 134 int X509_PURPOSE_get_count(void)
 135 {
 136         if(!xptable) return X509_PURPOSE_COUNT;
 137         return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
 138 }
 139
 140 X509_PURPOSE * X509_PURPOSE_get0(int idx)
 141 {
 142         if(idx < 0) return NULL;
 143         if(idx < X509_PURPOSE_COUNT) return xstandard + idx;
 144         return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
 145 }
 146
 147 int X509_PURPOSE_get_by_sname(char *sname)
 148 {
 149         int i;
 150         X509_PURPOSE *xptmp;
 151         for(i = 0; i < X509_PURPOSE_get_count(); i++) {
 152                 xptmp = X509_PURPOSE_get0(i);
 153                 if(!strcmp(xptmp->sname, sname)) return i;
 154         }
 155         return -1;
 156 }
 157
 158 int X509_PURPOSE_get_by_id(int purpose)
 159 {
 160         X509_PURPOSE tmp;
 161         int idx;
 162         if((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
 163                 return purpose - X509_PURPOSE_MIN;
 164         tmp.purpose = purpose;
 165         if(!xptable) return -1;
 166         idx = sk_X509_PURPOSE_find(xptable, &tmp);
 167         if(idx == -1) return -1;
 168         return idx + X509_PURPOSE_COUNT;
 169 }
 170
 171 int X509_PURPOSE_add(int id, int trust, int flags,
 172                         int (*ck)(const X509_PURPOSE *, const X509 *, int),
 173                                         char *name, char *sname, void *arg)
 174 {
 175         int idx;
 176         X509_PURPOSE *ptmp;
 177         /* This is set according to what we change: application can't set it */
 178         flags &= ~X509_PURPOSE_DYNAMIC;
 179         /* This will always be set for application modified trust entries */
 180         flags |= X509_PURPOSE_DYNAMIC_NAME;
 181         /* Get existing entry if any */
 182         idx = X509_PURPOSE_get_by_id(id);
 183         /* Need a new entry */
 184         if(idx == -1) {
 185                 if(!(ptmp = OPENSSL_malloc(sizeof(X509_PURPOSE)))) {
 186                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 187                         return 0;
 188                 }
 189                 ptmp->flags = X509_PURPOSE_DYNAMIC;
 190         } else ptmp = X509_PURPOSE_get0(idx);
 191
 192         /* OPENSSL_free existing name if dynamic */
 193         if(ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
 194                 OPENSSL_free(ptmp->name);
 195                 OPENSSL_free(ptmp->sname);
 196         }
 197         /* dup supplied name */
 198         ptmp->name = BUF_strdup(name);
 199         ptmp->sname = BUF_strdup(sname);
 200         if(!ptmp->name || !ptmp->sname) {
 201                 X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 202                 return 0;
 203         }
 204         /* Keep the dynamic flag of existing entry */
 205         ptmp->flags &= X509_PURPOSE_DYNAMIC;
 206         /* Set all other flags */
 207         ptmp->flags |= flags;
 208
 209         ptmp->purpose = id;
 210         ptmp->trust = trust;
 211         ptmp->check_purpose = ck;
 212         ptmp->usr_data = arg;
 213
 214         /* If its a new entry manage the dynamic table */
 215         if(idx == -1) {
 216                 if(!xptable && !(xptable = sk_X509_PURPOSE_new(xp_cmp))) {
 217                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 218                         return 0;
 219                 }
 220                 if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
 221                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 222                         return 0;
 223                 }
 224         }
 225         return 1;
 226 }
 227
 228 static void xptable_free(X509_PURPOSE *p)
 229         {
 230         if(!p) return;
 231         if (p->flags & X509_PURPOSE_DYNAMIC)
 232                 {
 233                 if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
 234                         OPENSSL_free(p->name);
 235                         OPENSSL_free(p->sname);
 236                 }
 237                 OPENSSL_free(p);
 238                 }
 239         }
 240
 241 void X509_PURPOSE_cleanup(void)
 242 {
 243         int i;
 244         sk_X509_PURPOSE_pop_free(xptable, xptable_free);
 245         for(i = 0; i < X509_PURPOSE_COUNT; i++) xptable_free(xstandard + i);
 246         xptable = NULL;
 247 }
 248
 249 int X509_PURPOSE_get_id(X509_PURPOSE *xp)
 250 {
 251         return xp->purpose;
 252 }
 253
 254 char *X509_PURPOSE_get0_name(X509_PURPOSE *xp)
 255 {
 256         return xp->name;
 257 }
 258
 259 char *X509_PURPOSE_get0_sname(X509_PURPOSE *xp)
 260 {
 261         return xp->sname;
 262 }
 263
 264 int X509_PURPOSE_get_trust(X509_PURPOSE *xp)
 265 {
 266         return xp->trust;
 267 }
 268
 269 static void x509v3_cache_extensions(X509 *x)
 270 {
 271         BASIC_CONSTRAINTS *bs;
 272         ASN1_BIT_STRING *usage;
 273         ASN1_BIT_STRING *ns;
 274         EXTENDED_KEY_USAGE *extusage;
 275
 276         int i;
 277         if(x->ex_flags & EXFLAG_SET) return;
 278 #ifndef OPENSSL_NO_SHA
 279         X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 280 #endif
 281         /* Does subject name match issuer ? */
 282         if(!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
 283                          x->ex_flags |= EXFLAG_SS;
 284         /* V1 should mean no extensions ... */
 285         if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
 286         /* Handle basic constraints */
 287         if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 288                 if(bs->ca) x->ex_flags |= EXFLAG_CA;
 289                 if(bs->pathlen) {
 290                         if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 291                                                 || !bs->ca) {
 292                                 x->ex_flags |= EXFLAG_INVALID;
 293                                 x->ex_pathlen = 0;
 294                         } else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 295                 } else x->ex_pathlen = -1;
 296                 BASIC_CONSTRAINTS_free(bs);
 297                 x->ex_flags |= EXFLAG_BCONS;
 298         }
 299         /* Handle key usage */
 300         if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 301                 if(usage->length > 0) {
 302                         x->ex_kusage = usage->data[0];
 303                         if(usage->length > 1)
 304                                 x->ex_kusage |= usage->data[1] << 8;
 305                 } else x->ex_kusage = 0;
 306                 x->ex_flags |= EXFLAG_KUSAGE;
 307                 ASN1_BIT_STRING_free(usage);
 308         }
 309         x->ex_xkusage = 0;
 310         if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 311                 x->ex_flags |= EXFLAG_XKUSAGE;
 312                 for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 313                         switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
 314                                 case NID_server_auth:
 315                                 x->ex_xkusage |= XKU_SSL_SERVER;
 316                                 break;
 317
 318                                 case NID_client_auth:
 319                                 x->ex_xkusage |= XKU_SSL_CLIENT;
 320                                 break;
 321
 322                                 case NID_email_protect:
 323                                 x->ex_xkusage |= XKU_SMIME;
 324                                 break;
 325
 326                                 case NID_code_sign:
 327                                 x->ex_xkusage |= XKU_CODE_SIGN;
 328                                 break;
 329
 330                                 case NID_ms_sgc:
 331                                 case NID_ns_sgc:
 332                                 x->ex_xkusage |= XKU_SGC;
 333                                 break;
 334
 335                                 case NID_OCSP_sign:
 336                                 x->ex_xkusage |= XKU_OCSP_SIGN;
 337                                 break;
 338
 339                                 case NID_time_stamp:
 340                                 x->ex_xkusage |= XKU_TIMESTAMP;
 341                                 break;
 342                         }
 343                 }
 344                 sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 345         }
 346
 347         if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 348                 if(ns->length > 0) x->ex_nscert = ns->data[0];
 349                 else x->ex_nscert = 0;
 350                 x->ex_flags |= EXFLAG_NSCERT;
 351                 ASN1_BIT_STRING_free(ns);
 352         }
 353         x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 354         x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 355         x->ex_flags |= EXFLAG_SET;
 356 }
 357
 358 /* CA checks common to all purposes
 359  * return codes:
 360  * 0 not a CA
 361  * 1 is a CA
 362  * 2 basicConstraints absent so "maybe" a CA
 363  * 3 basicConstraints absent but self signed V1.
 364  */
 365
 366 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 367 #define ku_reject(x, usage) \
 368         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 369 #define xku_reject(x, usage) \
 370         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 371 #define ns_reject(x, usage) \
 372         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 373
 374 static int ca_check(const X509 *x)
 375 {
 376         /* keyUsage if present should allow cert signing */
 377         if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
 378         if(x->ex_flags & EXFLAG_BCONS) {
 379                 if(x->ex_flags & EXFLAG_CA) return 1;
 380                 /* If basicConstraints says not a CA then say so */
 381                 else return 0;
 382         } else {
 383                 if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
 384                 /* If key usage present it must have certSign so tolerate it */
 385                 else if (x->ex_flags & EXFLAG_KUSAGE) return 3;
 386                 else return 2;
 387         }
 388 }
 389
 390 /* Check SSL CA: common checks for SSL client and server */
 391 static int check_ssl_ca(const X509 *x)
 392 {
 393         int ca_ret;
 394         ca_ret = ca_check(x);
 395         if(!ca_ret) return 0;
 396         /* check nsCertType if present */
 397         if(x->ex_flags & EXFLAG_NSCERT) {
 398                 if(x->ex_nscert & NS_SSL_CA) return ca_ret;
 399                 return 0;
 400         }
 401         if(ca_ret != 2) return ca_ret;
 402         else return 0;
 403 }
 404
 405
 406 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
 407 {
 408         if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
 409         if(ca) return check_ssl_ca(x);
 410         /* We need to do digital signatures with it */
 411         if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
 412         /* nsCertType if present should allow SSL client use */
 413         if(ns_reject(x, NS_SSL_CLIENT)) return 0;
 414         return 1;
 415 }
 416
 417 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 418 {
 419         if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
 420         if(ca) return check_ssl_ca(x);
 421
 422         if(ns_reject(x, NS_SSL_SERVER)) return 0;
 423         /* Now as for keyUsage: we'll at least need to sign OR encipher */
 424         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
 425
 426         return 1;
 427
 428 }
 429
 430 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 431 {
 432         int ret;
 433         ret = check_purpose_ssl_server(xp, x, ca);
 434         if(!ret || ca) return ret;
 435         /* We need to encipher or Netscape complains */
 436         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 437         return ret;
 438 }
 439
 440 /* common S/MIME checks */
 441 static int purpose_smime(const X509 *x, int ca)
 442 {
 443         if(xku_reject(x,XKU_SMIME)) return 0;
 444         if(ca) {
 445                 int ca_ret;
 446                 ca_ret = ca_check(x);
 447                 if(!ca_ret) return 0;
 448                 /* check nsCertType if present */
 449                 if(x->ex_flags & EXFLAG_NSCERT) {
 450                         if(x->ex_nscert & NS_SMIME_CA) return ca_ret;
 451                         return 0;
 452                 }
 453                 if(ca_ret != 2) return ca_ret;
 454                 else return 0;
 455         }
 456         if(x->ex_flags & EXFLAG_NSCERT) {
 457                 if(x->ex_nscert & NS_SMIME) return 1;
 458                 /* Workaround for some buggy certificates */
 459                 if(x->ex_nscert & NS_SSL_CLIENT) return 2;
 460                 return 0;
 461         }
 462         return 1;
 463 }
 464
 465 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 466 {
 467         int ret;
 468         ret = purpose_smime(x, ca);
 469         if(!ret || ca) return ret;
 470         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
 471         return ret;
 472 }
 473
 474 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
 475 {
 476         int ret;
 477         ret = purpose_smime(x, ca);
 478         if(!ret || ca) return ret;
 479         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 480         return ret;
 481 }
 482
 483 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 484 {
 485         if(ca) {
 486                 int ca_ret;
 487                 if((ca_ret = ca_check(x)) != 2) return ca_ret;
 488                 else return 0;
 489         }
 490         if(ku_reject(x, KU_CRL_SIGN)) return 0;
 491         return 1;
 492 }
 493
 494 /* OCSP helper: this is *not* a full OCSP check. It just checks that
 495  * each CA is valid. Additional checks must be made on the chain.
 496  */
 497
 498 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 499 {
 500         /* Must be a valid CA */
 501         if(ca) {
 502                 int ca_ret;
 503                 ca_ret = ca_check(x);
 504                 if(ca_ret != 2) return ca_ret;
 505                 if(x->ex_flags & EXFLAG_NSCERT) {
 506                         if(x->ex_nscert & NS_ANY_CA) return ca_ret;
 507                         return 0;
 508                 }
 509                 return 0;
 510         }
 511         /* leaf certificate is checked in OCSP_verify() */
 512         return 1;
 513 }
 514
 515 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 516 {
 517         return 1;
 518 }
 519
 520 /* Various checks to see if one certificate issued the second.
 521  * This can be used to prune a set of possible issuer certificates
 522  * which have been looked up using some simple method such as by
 523  * subject name.
 524  * These are:
 525  * 1. Check issuer_name(subject) == subject_name(issuer)
 526  * 2. If akid(subject) exists check it matches issuer
 527  * 3. If key_usage(issuer) exists check it supports certificate signing
 528  * returns 0 for OK, positive for reason for mismatch, reasons match
 529  * codes for X509_verify_cert()
 530  */
 531
 532 int X509_check_issued(X509 *issuer, X509 *subject)
 533 {
 534         if(X509_NAME_cmp(X509_get_subject_name(issuer),
 535                         X509_get_issuer_name(subject)))
 536                                 return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 537         x509v3_cache_extensions(issuer);
 538         x509v3_cache_extensions(subject);
 539         if(subject->akid) {
 540                 /* Check key ids (if present) */
 541                 if(subject->akid->keyid && issuer->skid &&
 542                  ASN1_OCTET_STRING_cmp(subject->akid->keyid, issuer->skid) )
 543                                 return X509_V_ERR_AKID_SKID_MISMATCH;
 544                 /* Check serial number */
 545                 if(subject->akid->serial &&
 546                         ASN1_INTEGER_cmp(X509_get_serialNumber(issuer),
 547                                                 subject->akid->serial))
 548                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 549                 /* Check issuer name */
 550                 if(subject->akid->issuer) {
 551                         /* Ugh, for some peculiar reason AKID includes
 552                          * SEQUENCE OF GeneralName. So look for a DirName.
 553                          * There may be more than one but we only take any
 554                          * notice of the first.
 555                          */
 556                         GENERAL_NAMES *gens;
 557                         GENERAL_NAME *gen;
 558                         X509_NAME *nm = NULL;
 559                         int i;
 560                         gens = subject->akid->issuer;
 561                         for(i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 562                                 gen = sk_GENERAL_NAME_value(gens, i);
 563                                 if(gen->type == GEN_DIRNAME) {
 564                                         nm = gen->d.dirn;
 565                                         break;
 566                                 }
 567                         }
 568                         if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 569                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 570                 }
 571         }
 572         if(ku_reject(issuer, KU_KEY_CERT_SIGN)) return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 573         return X509_V_OK;
 574 }
 575