crypto/x509v3/v3_purp.c

   1 /* v3_purp.c */
   2 /* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL
   3  * project 2001.
   4  */
   5 /* ====================================================================
   6  * Copyright (c) 1999-2001 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 int nid_cmp(int *a, int *b)
 270         {
 271         return *a - *b;
 272         }
 273
 274 int X509_supported_extension(X509_EXTENSION *ex)
 275         {
 276         /* This table is a list of the NIDs of supported extensions:
 277          * that is those which are used by the verify process. If
 278          * an extension is critical and doesn't appear in this list
 279          * then the verify process will normally reject the certificate.
 280          * The list must be kept in numerical order because it will be
 281          * searched using bsearch.
 282          */
 283
 284         static int supported_nids[] = {
 285                 NID_netscape_cert_type, /* 71 */
 286                 NID_key_usage,          /* 83 */
 287                 NID_subject_alt_name,   /* 85 */
 288                 NID_basic_constraints,  /* 87 */
 289                 NID_ext_key_usage       /* 126 */
 290         };
 291
 292         int ex_nid;
 293
 294         ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 295
 296         if (ex_nid == NID_undef)
 297                 return 0;
 298
 299         if (OBJ_bsearch((char *)&ex_nid, (char *)supported_nids,
 300                 sizeof(supported_nids)/sizeof(int), sizeof(int),
 301                 (int (*)(const void *, const void *))nid_cmp))
 302                 return 1;
 303         return 0;
 304         }
 305
 306
 307 static void x509v3_cache_extensions(X509 *x)
 308 {
 309         BASIC_CONSTRAINTS *bs;
 310         ASN1_BIT_STRING *usage;
 311         ASN1_BIT_STRING *ns;
 312         EXTENDED_KEY_USAGE *extusage;
 313         X509_EXTENSION *ex;
 314
 315         int i;
 316         if(x->ex_flags & EXFLAG_SET) return;
 317 #ifndef OPENSSL_NO_SHA
 318         X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 319 #endif
 320         /* Does subject name match issuer ? */
 321         if(!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
 322                          x->ex_flags |= EXFLAG_SS;
 323         /* V1 should mean no extensions ... */
 324         if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
 325         /* Handle basic constraints */
 326         if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 327                 if(bs->ca) x->ex_flags |= EXFLAG_CA;
 328                 if(bs->pathlen) {
 329                         if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 330                                                 || !bs->ca) {
 331                                 x->ex_flags |= EXFLAG_INVALID;
 332                                 x->ex_pathlen = 0;
 333                         } else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 334                 } else x->ex_pathlen = -1;
 335                 BASIC_CONSTRAINTS_free(bs);
 336                 x->ex_flags |= EXFLAG_BCONS;
 337         }
 338         /* Handle key usage */
 339         if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 340                 if(usage->length > 0) {
 341                         x->ex_kusage = usage->data[0];
 342                         if(usage->length > 1)
 343                                 x->ex_kusage |= usage->data[1] << 8;
 344                 } else x->ex_kusage = 0;
 345                 x->ex_flags |= EXFLAG_KUSAGE;
 346                 ASN1_BIT_STRING_free(usage);
 347         }
 348         x->ex_xkusage = 0;
 349         if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 350                 x->ex_flags |= EXFLAG_XKUSAGE;
 351                 for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 352                         switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
 353                                 case NID_server_auth:
 354                                 x->ex_xkusage |= XKU_SSL_SERVER;
 355                                 break;
 356
 357                                 case NID_client_auth:
 358                                 x->ex_xkusage |= XKU_SSL_CLIENT;
 359                                 break;
 360
 361                                 case NID_email_protect:
 362                                 x->ex_xkusage |= XKU_SMIME;
 363                                 break;
 364
 365                                 case NID_code_sign:
 366                                 x->ex_xkusage |= XKU_CODE_SIGN;
 367                                 break;
 368
 369                                 case NID_ms_sgc:
 370                                 case NID_ns_sgc:
 371                                 x->ex_xkusage |= XKU_SGC;
 372                                 break;
 373
 374                                 case NID_OCSP_sign:
 375                                 x->ex_xkusage |= XKU_OCSP_SIGN;
 376                                 break;
 377
 378                                 case NID_time_stamp:
 379                                 x->ex_xkusage |= XKU_TIMESTAMP;
 380                                 break;
 381
 382                                 case NID_dvcs:
 383                                 x->ex_xkusage |= XKU_DVCS;
 384                                 break;
 385                         }
 386                 }
 387                 sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 388         }
 389
 390         if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 391                 if(ns->length > 0) x->ex_nscert = ns->data[0];
 392                 else x->ex_nscert = 0;
 393                 x->ex_flags |= EXFLAG_NSCERT;
 394                 ASN1_BIT_STRING_free(ns);
 395         }
 396         x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 397         x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 398         for (i = 0; i < X509_get_ext_count(x); i++)
 399                 {
 400                 ex = X509_get_ext(x, i);
 401                 if (!X509_EXTENSION_get_critical(ex))
 402                         continue;
 403                 if (!X509_supported_extension(ex))
 404                         {
 405                         x->ex_flags |= EXFLAG_CRITICAL;
 406                         break;
 407                         }
 408                 }
 409         x->ex_flags |= EXFLAG_SET;
 410 }
 411
 412 /* CA checks common to all purposes
 413  * return codes:
 414  * 0 not a CA
 415  * 1 is a CA
 416  * 2 basicConstraints absent so "maybe" a CA
 417  * 3 basicConstraints absent but self signed V1.
 418  */
 419
 420 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 421 #define ku_reject(x, usage) \
 422         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 423 #define xku_reject(x, usage) \
 424         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 425 #define ns_reject(x, usage) \
 426         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 427
 428 static int ca_check(const X509 *x)
 429 {
 430         /* keyUsage if present should allow cert signing */
 431         if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
 432         if(x->ex_flags & EXFLAG_BCONS) {
 433                 if(x->ex_flags & EXFLAG_CA) return 1;
 434                 /* If basicConstraints says not a CA then say so */
 435                 else return 0;
 436         } else {
 437                 if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
 438                 /* If key usage present it must have certSign so tolerate it */
 439                 else if (x->ex_flags & EXFLAG_KUSAGE) return 3;
 440                 else return 2;
 441         }
 442 }
 443
 444 /* Check SSL CA: common checks for SSL client and server */
 445 static int check_ssl_ca(const X509 *x)
 446 {
 447         int ca_ret;
 448         ca_ret = ca_check(x);
 449         if(!ca_ret) return 0;
 450         /* check nsCertType if present */
 451         if(x->ex_flags & EXFLAG_NSCERT) {
 452                 if(x->ex_nscert & NS_SSL_CA) return ca_ret;
 453                 return 0;
 454         }
 455         if(ca_ret != 2) return ca_ret;
 456         else return 0;
 457 }
 458
 459
 460 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
 461 {
 462         if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
 463         if(ca) return check_ssl_ca(x);
 464         /* We need to do digital signatures with it */
 465         if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
 466         /* nsCertType if present should allow SSL client use */
 467         if(ns_reject(x, NS_SSL_CLIENT)) return 0;
 468         return 1;
 469 }
 470
 471 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 472 {
 473         if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
 474         if(ca) return check_ssl_ca(x);
 475
 476         if(ns_reject(x, NS_SSL_SERVER)) return 0;
 477         /* Now as for keyUsage: we'll at least need to sign OR encipher */
 478         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
 479
 480         return 1;
 481
 482 }
 483
 484 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 485 {
 486         int ret;
 487         ret = check_purpose_ssl_server(xp, x, ca);
 488         if(!ret || ca) return ret;
 489         /* We need to encipher or Netscape complains */
 490         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 491         return ret;
 492 }
 493
 494 /* common S/MIME checks */
 495 static int purpose_smime(const X509 *x, int ca)
 496 {
 497         if(xku_reject(x,XKU_SMIME)) return 0;
 498         if(ca) {
 499                 int ca_ret;
 500                 ca_ret = ca_check(x);
 501                 if(!ca_ret) return 0;
 502                 /* check nsCertType if present */
 503                 if(x->ex_flags & EXFLAG_NSCERT) {
 504                         if(x->ex_nscert & NS_SMIME_CA) return ca_ret;
 505                         return 0;
 506                 }
 507                 if(ca_ret != 2) return ca_ret;
 508                 else return 0;
 509         }
 510         if(x->ex_flags & EXFLAG_NSCERT) {
 511                 if(x->ex_nscert & NS_SMIME) return 1;
 512                 /* Workaround for some buggy certificates */
 513                 if(x->ex_nscert & NS_SSL_CLIENT) return 2;
 514                 return 0;
 515         }
 516         return 1;
 517 }
 518
 519 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 520 {
 521         int ret;
 522         ret = purpose_smime(x, ca);
 523         if(!ret || ca) return ret;
 524         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
 525         return ret;
 526 }
 527
 528 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
 529 {
 530         int ret;
 531         ret = purpose_smime(x, ca);
 532         if(!ret || ca) return ret;
 533         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 534         return ret;
 535 }
 536
 537 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 538 {
 539         if(ca) {
 540                 int ca_ret;
 541                 if((ca_ret = ca_check(x)) != 2) return ca_ret;
 542                 else return 0;
 543         }
 544         if(ku_reject(x, KU_CRL_SIGN)) return 0;
 545         return 1;
 546 }
 547
 548 /* OCSP helper: this is *not* a full OCSP check. It just checks that
 549  * each CA is valid. Additional checks must be made on the chain.
 550  */
 551
 552 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 553 {
 554         /* Must be a valid CA */
 555         if(ca) {
 556                 int ca_ret;
 557                 ca_ret = ca_check(x);
 558                 if(ca_ret != 2) return ca_ret;
 559                 if(x->ex_flags & EXFLAG_NSCERT) {
 560                         if(x->ex_nscert & NS_ANY_CA) return ca_ret;
 561                         return 0;
 562                 }
 563                 return 0;
 564         }
 565         /* leaf certificate is checked in OCSP_verify() */
 566         return 1;
 567 }
 568
 569 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 570 {
 571         return 1;
 572 }
 573
 574 /* Various checks to see if one certificate issued the second.
 575  * This can be used to prune a set of possible issuer certificates
 576  * which have been looked up using some simple method such as by
 577  * subject name.
 578  * These are:
 579  * 1. Check issuer_name(subject) == subject_name(issuer)
 580  * 2. If akid(subject) exists check it matches issuer
 581  * 3. If key_usage(issuer) exists check it supports certificate signing
 582  * returns 0 for OK, positive for reason for mismatch, reasons match
 583  * codes for X509_verify_cert()
 584  */
 585
 586 int X509_check_issued(X509 *issuer, X509 *subject)
 587 {
 588         if(X509_NAME_cmp(X509_get_subject_name(issuer),
 589                         X509_get_issuer_name(subject)))
 590                                 return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 591         x509v3_cache_extensions(issuer);
 592         x509v3_cache_extensions(subject);
 593         if(subject->akid) {
 594                 /* Check key ids (if present) */
 595                 if(subject->akid->keyid && issuer->skid &&
 596                  ASN1_OCTET_STRING_cmp(subject->akid->keyid, issuer->skid) )
 597                                 return X509_V_ERR_AKID_SKID_MISMATCH;
 598                 /* Check serial number */
 599                 if(subject->akid->serial &&
 600                         ASN1_INTEGER_cmp(X509_get_serialNumber(issuer),
 601                                                 subject->akid->serial))
 602                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 603                 /* Check issuer name */
 604                 if(subject->akid->issuer) {
 605                         /* Ugh, for some peculiar reason AKID includes
 606                          * SEQUENCE OF GeneralName. So look for a DirName.
 607                          * There may be more than one but we only take any
 608                          * notice of the first.
 609                          */
 610                         GENERAL_NAMES *gens;
 611                         GENERAL_NAME *gen;
 612                         X509_NAME *nm = NULL;
 613                         int i;
 614                         gens = subject->akid->issuer;
 615                         for(i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 616                                 gen = sk_GENERAL_NAME_value(gens, i);
 617                                 if(gen->type == GEN_DIRNAME) {
 618                                         nm = gen->d.dirn;
 619                                         break;
 620                                 }
 621                         }
 622                         if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 623                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 624                 }
 625         }
 626         if(ku_reject(issuer, KU_KEY_CERT_SIGN)) return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 627         return X509_V_OK;
 628 }
 629