crypto/openssl-0.9/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) 1999-2004 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 "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 check_ssl_ca(const X509 *x);
  67 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca);
  68 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
  69 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
  70 static int purpose_smime(const X509 *x, int ca);
  71 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
  72 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca);
  73 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
  74 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
  75 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
  76
  77 static int xp_cmp(const X509_PURPOSE * const *a,
  78                 const X509_PURPOSE * const *b);
  79 static void xptable_free(X509_PURPOSE *p);
  80
  81 static X509_PURPOSE xstandard[] = {
  82         {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0, check_purpose_ssl_client, "SSL client", "sslclient", NULL},
  83         {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ssl_server, "SSL server", "sslserver", NULL},
  84         {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
  85         {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign, "S/MIME signing", "smimesign", NULL},
  86         {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0, check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
  87         {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign, "CRL signing", "crlsign", NULL},
  88         {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any", NULL},
  89         {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper, "OCSP helper", "ocsphelper", NULL},
  90 };
  91
  92 #define X509_PURPOSE_COUNT (sizeof(xstandard)/sizeof(X509_PURPOSE))
  93
  94 IMPLEMENT_STACK_OF(X509_PURPOSE)
  95
  96 static STACK_OF(X509_PURPOSE) *xptable = NULL;
  97
  98 static int xp_cmp(const X509_PURPOSE * const *a,
  99                 const X509_PURPOSE * const *b)
 100 {
 101         return (*a)->purpose - (*b)->purpose;
 102 }
 103
 104 /* As much as I'd like to make X509_check_purpose use a "const" X509*
 105  * I really can't because it does recalculate hashes and do other non-const
 106  * things. */
 107 int X509_check_purpose(X509 *x, int id, int ca)
 108 {
 109         int idx;
 110         const X509_PURPOSE *pt;
 111         if(!(x->ex_flags & EXFLAG_SET)) {
 112                 CRYPTO_w_lock(CRYPTO_LOCK_X509);
 113                 x509v3_cache_extensions(x);
 114                 CRYPTO_w_unlock(CRYPTO_LOCK_X509);
 115         }
 116         if(id == -1) return 1;
 117         idx = X509_PURPOSE_get_by_id(id);
 118         if(idx == -1) return -1;
 119         pt = X509_PURPOSE_get0(idx);
 120         return pt->check_purpose(pt, x, ca);
 121 }
 122
 123 int X509_PURPOSE_set(int *p, int purpose)
 124 {
 125         if(X509_PURPOSE_get_by_id(purpose) == -1) {
 126                 X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
 127                 return 0;
 128         }
 129         *p = purpose;
 130         return 1;
 131 }
 132
 133 int X509_PURPOSE_get_count(void)
 134 {
 135         if(!xptable) return X509_PURPOSE_COUNT;
 136         return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
 137 }
 138
 139 X509_PURPOSE * X509_PURPOSE_get0(int idx)
 140 {
 141         if(idx < 0) return NULL;
 142         if(idx < (int)X509_PURPOSE_COUNT) return xstandard + idx;
 143         return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
 144 }
 145
 146 int X509_PURPOSE_get_by_sname(char *sname)
 147 {
 148         int i;
 149         X509_PURPOSE *xptmp;
 150         for(i = 0; i < X509_PURPOSE_get_count(); i++) {
 151                 xptmp = X509_PURPOSE_get0(i);
 152                 if(!strcmp(xptmp->sname, sname)) return i;
 153         }
 154         return -1;
 155 }
 156
 157 int X509_PURPOSE_get_by_id(int purpose)
 158 {
 159         X509_PURPOSE tmp;
 160         int idx;
 161         if((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
 162                 return purpose - X509_PURPOSE_MIN;
 163         tmp.purpose = purpose;
 164         if(!xptable) return -1;
 165         idx = sk_X509_PURPOSE_find(xptable, &tmp);
 166         if(idx == -1) return -1;
 167         return idx + X509_PURPOSE_COUNT;
 168 }
 169
 170 int X509_PURPOSE_add(int id, int trust, int flags,
 171                         int (*ck)(const X509_PURPOSE *, const X509 *, int),
 172                                         char *name, char *sname, void *arg)
 173 {
 174         int idx;
 175         X509_PURPOSE *ptmp;
 176         /* This is set according to what we change: application can't set it */
 177         flags &= ~X509_PURPOSE_DYNAMIC;
 178         /* This will always be set for application modified trust entries */
 179         flags |= X509_PURPOSE_DYNAMIC_NAME;
 180         /* Get existing entry if any */
 181         idx = X509_PURPOSE_get_by_id(id);
 182         /* Need a new entry */
 183         if(idx == -1) {
 184                 if(!(ptmp = OPENSSL_malloc(sizeof(X509_PURPOSE)))) {
 185                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 186                         return 0;
 187                 }
 188                 ptmp->flags = X509_PURPOSE_DYNAMIC;
 189         } else ptmp = X509_PURPOSE_get0(idx);
 190
 191         /* OPENSSL_free existing name if dynamic */
 192         if(ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
 193                 OPENSSL_free(ptmp->name);
 194                 OPENSSL_free(ptmp->sname);
 195         }
 196         /* dup supplied name */
 197         ptmp->name = BUF_strdup(name);
 198         ptmp->sname = BUF_strdup(sname);
 199         if(!ptmp->name || !ptmp->sname) {
 200                 X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 201                 return 0;
 202         }
 203         /* Keep the dynamic flag of existing entry */
 204         ptmp->flags &= X509_PURPOSE_DYNAMIC;
 205         /* Set all other flags */
 206         ptmp->flags |= flags;
 207
 208         ptmp->purpose = id;
 209         ptmp->trust = trust;
 210         ptmp->check_purpose = ck;
 211         ptmp->usr_data = arg;
 212
 213         /* If its a new entry manage the dynamic table */
 214         if(idx == -1) {
 215                 if(!xptable && !(xptable = sk_X509_PURPOSE_new(xp_cmp))) {
 216                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 217                         return 0;
 218                 }
 219                 if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
 220                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 221                         return 0;
 222                 }
 223         }
 224         return 1;
 225 }
 226
 227 static void xptable_free(X509_PURPOSE *p)
 228         {
 229         if(!p) return;
 230         if (p->flags & X509_PURPOSE_DYNAMIC)
 231                 {
 232                 if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
 233                         OPENSSL_free(p->name);
 234                         OPENSSL_free(p->sname);
 235                 }
 236                 OPENSSL_free(p);
 237                 }
 238         }
 239
 240 void X509_PURPOSE_cleanup(void)
 241 {
 242         unsigned int i;
 243         sk_X509_PURPOSE_pop_free(xptable, xptable_free);
 244         for(i = 0; i < X509_PURPOSE_COUNT; i++) xptable_free(xstandard + i);
 245         xptable = NULL;
 246 }
 247
 248 int X509_PURPOSE_get_id(X509_PURPOSE *xp)
 249 {
 250         return xp->purpose;
 251 }
 252
 253 char *X509_PURPOSE_get0_name(X509_PURPOSE *xp)
 254 {
 255         return xp->name;
 256 }
 257
 258 char *X509_PURPOSE_get0_sname(X509_PURPOSE *xp)
 259 {
 260         return xp->sname;
 261 }
 262
 263 int X509_PURPOSE_get_trust(X509_PURPOSE *xp)
 264 {
 265         return xp->trust;
 266 }
 267
 268 static int nid_cmp(int *a, int *b)
 269         {
 270         return *a - *b;
 271         }
 272
 273 int X509_supported_extension(X509_EXTENSION *ex)
 274         {
 275         /* This table is a list of the NIDs of supported extensions:
 276          * that is those which are used by the verify process. If
 277          * an extension is critical and doesn't appear in this list
 278          * then the verify process will normally reject the certificate.
 279          * The list must be kept in numerical order because it will be
 280          * searched using bsearch.
 281          */
 282
 283         static int supported_nids[] = {
 284                 NID_netscape_cert_type, /* 71 */
 285                 NID_key_usage,          /* 83 */
 286                 NID_subject_alt_name,   /* 85 */
 287                 NID_basic_constraints,  /* 87 */
 288                 NID_certificate_policies, /* 89 */
 289                 NID_ext_key_usage,      /* 126 */
 290 #ifndef OPENSSL_NO_RFC3779
 291                 NID_sbgp_ipAddrBlock,   /* 290 */
 292                 NID_sbgp_autonomousSysNum, /* 291 */
 293 #endif
 294                 NID_proxyCertInfo       /* 661 */
 295         };
 296
 297         int ex_nid;
 298
 299         ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 300
 301         if (ex_nid == NID_undef)
 302                 return 0;
 303
 304         if (OBJ_bsearch((char *)&ex_nid, (char *)supported_nids,
 305                 sizeof(supported_nids)/sizeof(int), sizeof(int),
 306                 (int (*)(const void *, const void *))nid_cmp))
 307                 return 1;
 308         return 0;
 309         }
 310
 311
 312 static void x509v3_cache_extensions(X509 *x)
 313 {
 314         BASIC_CONSTRAINTS *bs;
 315         PROXY_CERT_INFO_EXTENSION *pci;
 316         ASN1_BIT_STRING *usage;
 317         ASN1_BIT_STRING *ns;
 318         EXTENDED_KEY_USAGE *extusage;
 319         X509_EXTENSION *ex;
 320
 321         int i;
 322         if(x->ex_flags & EXFLAG_SET) return;
 323 #ifndef OPENSSL_NO_SHA
 324         X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 325 #endif
 326         /* Does subject name match issuer ? */
 327         if(!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
 328                          x->ex_flags |= EXFLAG_SS;
 329         /* V1 should mean no extensions ... */
 330         if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
 331         /* Handle basic constraints */
 332         if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 333                 if(bs->ca) x->ex_flags |= EXFLAG_CA;
 334                 if(bs->pathlen) {
 335                         if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 336                                                 || !bs->ca) {
 337                                 x->ex_flags |= EXFLAG_INVALID;
 338                                 x->ex_pathlen = 0;
 339                         } else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 340                 } else x->ex_pathlen = -1;
 341                 BASIC_CONSTRAINTS_free(bs);
 342                 x->ex_flags |= EXFLAG_BCONS;
 343         }
 344         /* Handle proxy certificates */
 345         if((pci=X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
 346                 if (x->ex_flags & EXFLAG_CA
 347                     || X509_get_ext_by_NID(x, NID_subject_alt_name, 0) >= 0
 348                     || X509_get_ext_by_NID(x, NID_issuer_alt_name, 0) >= 0) {
 349                         x->ex_flags |= EXFLAG_INVALID;
 350                 }
 351                 if (pci->pcPathLengthConstraint) {
 352                         x->ex_pcpathlen =
 353                                 ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 354                 } else x->ex_pcpathlen = -1;
 355                 PROXY_CERT_INFO_EXTENSION_free(pci);
 356                 x->ex_flags |= EXFLAG_PROXY;
 357         }
 358         /* Handle key usage */
 359         if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 360                 if(usage->length > 0) {
 361                         x->ex_kusage = usage->data[0];
 362                         if(usage->length > 1)
 363                                 x->ex_kusage |= usage->data[1] << 8;
 364                 } else x->ex_kusage = 0;
 365                 x->ex_flags |= EXFLAG_KUSAGE;
 366                 ASN1_BIT_STRING_free(usage);
 367         }
 368         x->ex_xkusage = 0;
 369         if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 370                 x->ex_flags |= EXFLAG_XKUSAGE;
 371                 for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 372                         switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
 373                                 case NID_server_auth:
 374                                 x->ex_xkusage |= XKU_SSL_SERVER;
 375                                 break;
 376
 377                                 case NID_client_auth:
 378                                 x->ex_xkusage |= XKU_SSL_CLIENT;
 379                                 break;
 380
 381                                 case NID_email_protect:
 382                                 x->ex_xkusage |= XKU_SMIME;
 383                                 break;
 384
 385                                 case NID_code_sign:
 386                                 x->ex_xkusage |= XKU_CODE_SIGN;
 387                                 break;
 388
 389                                 case NID_ms_sgc:
 390                                 case NID_ns_sgc:
 391                                 x->ex_xkusage |= XKU_SGC;
 392                                 break;
 393
 394                                 case NID_OCSP_sign:
 395                                 x->ex_xkusage |= XKU_OCSP_SIGN;
 396                                 break;
 397
 398                                 case NID_time_stamp:
 399                                 x->ex_xkusage |= XKU_TIMESTAMP;
 400                                 break;
 401
 402                                 case NID_dvcs:
 403                                 x->ex_xkusage |= XKU_DVCS;
 404                                 break;
 405                         }
 406                 }
 407                 sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 408         }
 409
 410         if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 411                 if(ns->length > 0) x->ex_nscert = ns->data[0];
 412                 else x->ex_nscert = 0;
 413                 x->ex_flags |= EXFLAG_NSCERT;
 414                 ASN1_BIT_STRING_free(ns);
 415         }
 416         x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 417         x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 418 #ifndef OPENSSL_NO_RFC3779
 419         x->rfc3779_addr =X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
 420         x->rfc3779_asid =X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
 421                                           NULL, NULL);
 422 #endif
 423         for (i = 0; i < X509_get_ext_count(x); i++)
 424                 {
 425                 ex = X509_get_ext(x, i);
 426                 if (!X509_EXTENSION_get_critical(ex))
 427                         continue;
 428                 if (!X509_supported_extension(ex))
 429                         {
 430                         x->ex_flags |= EXFLAG_CRITICAL;
 431                         break;
 432                         }
 433                 }
 434         x->ex_flags |= EXFLAG_SET;
 435 }
 436
 437 /* CA checks common to all purposes
 438  * return codes:
 439  * 0 not a CA
 440  * 1 is a CA
 441  * 2 basicConstraints absent so "maybe" a CA
 442  * 3 basicConstraints absent but self signed V1.
 443  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 444  */
 445
 446 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 447 #define ku_reject(x, usage) \
 448         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 449 #define xku_reject(x, usage) \
 450         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 451 #define ns_reject(x, usage) \
 452         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 453
 454 static int check_ca(const X509 *x)
 455 {
 456         /* keyUsage if present should allow cert signing */
 457         if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
 458         if(x->ex_flags & EXFLAG_BCONS) {
 459                 if(x->ex_flags & EXFLAG_CA) return 1;
 460                 /* If basicConstraints says not a CA then say so */
 461                 else return 0;
 462         } else {
 463                 /* we support V1 roots for...  uh, I don't really know why. */
 464                 if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
 465                 /* If key usage present it must have certSign so tolerate it */
 466                 else if (x->ex_flags & EXFLAG_KUSAGE) return 4;
 467                 /* Older certificates could have Netscape-specific CA types */
 468                 else if (x->ex_flags & EXFLAG_NSCERT
 469                          && x->ex_nscert & NS_ANY_CA) return 5;
 470                 /* can this still be regarded a CA certificate?  I doubt it */
 471                 return 0;
 472         }
 473 }
 474
 475 int X509_check_ca(X509 *x)
 476 {
 477         if(!(x->ex_flags & EXFLAG_SET)) {
 478                 CRYPTO_w_lock(CRYPTO_LOCK_X509);
 479                 x509v3_cache_extensions(x);
 480                 CRYPTO_w_unlock(CRYPTO_LOCK_X509);
 481         }
 482
 483         return check_ca(x);
 484 }
 485
 486 /* Check SSL CA: common checks for SSL client and server */
 487 static int check_ssl_ca(const X509 *x)
 488 {
 489         int ca_ret;
 490         ca_ret = check_ca(x);
 491         if(!ca_ret) return 0;
 492         /* check nsCertType if present */
 493         if(ca_ret != 5 || x->ex_nscert & NS_SSL_CA) return ca_ret;
 494         else return 0;
 495 }
 496
 497
 498 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
 499 {
 500         if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
 501         if(ca) return check_ssl_ca(x);
 502         /* We need to do digital signatures with it */
 503         if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
 504         /* nsCertType if present should allow SSL client use */
 505         if(ns_reject(x, NS_SSL_CLIENT)) return 0;
 506         return 1;
 507 }
 508
 509 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 510 {
 511         if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
 512         if(ca) return check_ssl_ca(x);
 513
 514         if(ns_reject(x, NS_SSL_SERVER)) return 0;
 515         /* Now as for keyUsage: we'll at least need to sign OR encipher */
 516         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
 517
 518         return 1;
 519
 520 }
 521
 522 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 523 {
 524         int ret;
 525         ret = check_purpose_ssl_server(xp, x, ca);
 526         if(!ret || ca) return ret;
 527         /* We need to encipher or Netscape complains */
 528         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 529         return ret;
 530 }
 531
 532 /* common S/MIME checks */
 533 static int purpose_smime(const X509 *x, int ca)
 534 {
 535         if(xku_reject(x,XKU_SMIME)) return 0;
 536         if(ca) {
 537                 int ca_ret;
 538                 ca_ret = check_ca(x);
 539                 if(!ca_ret) return 0;
 540                 /* check nsCertType if present */
 541                 if(ca_ret != 5 || x->ex_nscert & NS_SMIME_CA) return ca_ret;
 542                 else return 0;
 543         }
 544         if(x->ex_flags & EXFLAG_NSCERT) {
 545                 if(x->ex_nscert & NS_SMIME) return 1;
 546                 /* Workaround for some buggy certificates */
 547                 if(x->ex_nscert & NS_SSL_CLIENT) return 2;
 548                 return 0;
 549         }
 550         return 1;
 551 }
 552
 553 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 554 {
 555         int ret;
 556         ret = purpose_smime(x, ca);
 557         if(!ret || ca) return ret;
 558         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
 559         return ret;
 560 }
 561
 562 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
 563 {
 564         int ret;
 565         ret = purpose_smime(x, ca);
 566         if(!ret || ca) return ret;
 567         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 568         return ret;
 569 }
 570
 571 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 572 {
 573         if(ca) {
 574                 int ca_ret;
 575                 if((ca_ret = check_ca(x)) != 2) return ca_ret;
 576                 else return 0;
 577         }
 578         if(ku_reject(x, KU_CRL_SIGN)) return 0;
 579         return 1;
 580 }
 581
 582 /* OCSP helper: this is *not* a full OCSP check. It just checks that
 583  * each CA is valid. Additional checks must be made on the chain.
 584  */
 585
 586 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 587 {
 588         /* Must be a valid CA.  Should we really support the "I don't know"
 589            value (2)? */
 590         if(ca) return check_ca(x);
 591         /* leaf certificate is checked in OCSP_verify() */
 592         return 1;
 593 }
 594
 595 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 596 {
 597         return 1;
 598 }
 599
 600 /* Various checks to see if one certificate issued the second.
 601  * This can be used to prune a set of possible issuer certificates
 602  * which have been looked up using some simple method such as by
 603  * subject name.
 604  * These are:
 605  * 1. Check issuer_name(subject) == subject_name(issuer)
 606  * 2. If akid(subject) exists check it matches issuer
 607  * 3. If key_usage(issuer) exists check it supports certificate signing
 608  * returns 0 for OK, positive for reason for mismatch, reasons match
 609  * codes for X509_verify_cert()
 610  */
 611
 612 int X509_check_issued(X509 *issuer, X509 *subject)
 613 {
 614         if(X509_NAME_cmp(X509_get_subject_name(issuer),
 615                         X509_get_issuer_name(subject)))
 616                                 return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 617         x509v3_cache_extensions(issuer);
 618         x509v3_cache_extensions(subject);
 619         if(subject->akid) {
 620                 /* Check key ids (if present) */
 621                 if(subject->akid->keyid && issuer->skid &&
 622                  ASN1_OCTET_STRING_cmp(subject->akid->keyid, issuer->skid) )
 623                                 return X509_V_ERR_AKID_SKID_MISMATCH;
 624                 /* Check serial number */
 625                 if(subject->akid->serial &&
 626                         ASN1_INTEGER_cmp(X509_get_serialNumber(issuer),
 627                                                 subject->akid->serial))
 628                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 629                 /* Check issuer name */
 630                 if(subject->akid->issuer) {
 631                         /* Ugh, for some peculiar reason AKID includes
 632                          * SEQUENCE OF GeneralName. So look for a DirName.
 633                          * There may be more than one but we only take any
 634                          * notice of the first.
 635                          */
 636                         GENERAL_NAMES *gens;
 637                         GENERAL_NAME *gen;
 638                         X509_NAME *nm = NULL;
 639                         int i;
 640                         gens = subject->akid->issuer;
 641                         for(i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 642                                 gen = sk_GENERAL_NAME_value(gens, i);
 643                                 if(gen->type == GEN_DIRNAME) {
 644                                         nm = gen->d.dirn;
 645                                         break;
 646                                 }
 647                         }
 648                         if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 649                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 650                 }
 651         }
 652         if(subject->ex_flags & EXFLAG_PROXY)
 653                 {
 654                 if(ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 655                         return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 656                 }
 657         else if(ku_reject(issuer, KU_KEY_CERT_SIGN))
 658                 return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 659         return X509_V_OK;
 660 }
 661