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_policy_constraints, /* 401 */
 295                 NID_proxyCertInfo       /* 661 */
 296         };
 297
 298         int ex_nid;
 299
 300         ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 301
 302         if (ex_nid == NID_undef)
 303                 return 0;
 304
 305         if (OBJ_bsearch((char *)&ex_nid, (char *)supported_nids,
 306                 sizeof(supported_nids)/sizeof(int), sizeof(int),
 307                 (int (*)(const void *, const void *))nid_cmp))
 308                 return 1;
 309         return 0;
 310         }
 311
 312
 313 static void x509v3_cache_extensions(X509 *x)
 314 {
 315         BASIC_CONSTRAINTS *bs;
 316         PROXY_CERT_INFO_EXTENSION *pci;
 317         ASN1_BIT_STRING *usage;
 318         ASN1_BIT_STRING *ns;
 319         EXTENDED_KEY_USAGE *extusage;
 320         X509_EXTENSION *ex;
 321
 322         int i;
 323         if(x->ex_flags & EXFLAG_SET) return;
 324 #ifndef OPENSSL_NO_SHA
 325         X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 326 #endif
 327         /* Does subject name match issuer ? */
 328         if(!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
 329                          x->ex_flags |= EXFLAG_SI;
 330         /* V1 should mean no extensions ... */
 331         if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
 332         /* Handle basic constraints */
 333         if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 334                 if(bs->ca) x->ex_flags |= EXFLAG_CA;
 335                 if(bs->pathlen) {
 336                         if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 337                                                 || !bs->ca) {
 338                                 x->ex_flags |= EXFLAG_INVALID;
 339                                 x->ex_pathlen = 0;
 340                         } else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 341                 } else x->ex_pathlen = -1;
 342                 BASIC_CONSTRAINTS_free(bs);
 343                 x->ex_flags |= EXFLAG_BCONS;
 344         }
 345         /* Handle proxy certificates */
 346         if((pci=X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
 347                 if (x->ex_flags & EXFLAG_CA
 348                     || X509_get_ext_by_NID(x, NID_subject_alt_name, 0) >= 0
 349                     || X509_get_ext_by_NID(x, NID_issuer_alt_name, 0) >= 0) {
 350                         x->ex_flags |= EXFLAG_INVALID;
 351                 }
 352                 if (pci->pcPathLengthConstraint) {
 353                         x->ex_pcpathlen =
 354                                 ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 355                 } else x->ex_pcpathlen = -1;
 356                 PROXY_CERT_INFO_EXTENSION_free(pci);
 357                 x->ex_flags |= EXFLAG_PROXY;
 358         }
 359         /* Handle key usage */
 360         if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 361                 if(usage->length > 0) {
 362                         x->ex_kusage = usage->data[0];
 363                         if(usage->length > 1)
 364                                 x->ex_kusage |= usage->data[1] << 8;
 365                 } else x->ex_kusage = 0;
 366                 x->ex_flags |= EXFLAG_KUSAGE;
 367                 ASN1_BIT_STRING_free(usage);
 368         }
 369         x->ex_xkusage = 0;
 370         if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 371                 x->ex_flags |= EXFLAG_XKUSAGE;
 372                 for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 373                         switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
 374                                 case NID_server_auth:
 375                                 x->ex_xkusage |= XKU_SSL_SERVER;
 376                                 break;
 377
 378                                 case NID_client_auth:
 379                                 x->ex_xkusage |= XKU_SSL_CLIENT;
 380                                 break;
 381
 382                                 case NID_email_protect:
 383                                 x->ex_xkusage |= XKU_SMIME;
 384                                 break;
 385
 386                                 case NID_code_sign:
 387                                 x->ex_xkusage |= XKU_CODE_SIGN;
 388                                 break;
 389
 390                                 case NID_ms_sgc:
 391                                 case NID_ns_sgc:
 392                                 x->ex_xkusage |= XKU_SGC;
 393                                 break;
 394
 395                                 case NID_OCSP_sign:
 396                                 x->ex_xkusage |= XKU_OCSP_SIGN;
 397                                 break;
 398
 399                                 case NID_time_stamp:
 400                                 x->ex_xkusage |= XKU_TIMESTAMP;
 401                                 break;
 402
 403                                 case NID_dvcs:
 404                                 x->ex_xkusage |= XKU_DVCS;
 405                                 break;
 406                         }
 407                 }
 408                 sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 409         }
 410
 411         if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 412                 if(ns->length > 0) x->ex_nscert = ns->data[0];
 413                 else x->ex_nscert = 0;
 414                 x->ex_flags |= EXFLAG_NSCERT;
 415                 ASN1_BIT_STRING_free(ns);
 416         }
 417         x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 418         x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 419 #ifndef OPENSSL_NO_RFC3779
 420         x->rfc3779_addr =X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
 421         x->rfc3779_asid =X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
 422                                           NULL, NULL);
 423 #endif
 424         for (i = 0; i < X509_get_ext_count(x); i++)
 425                 {
 426                 ex = X509_get_ext(x, i);
 427                 if (!X509_EXTENSION_get_critical(ex))
 428                         continue;
 429                 if (!X509_supported_extension(ex))
 430                         {
 431                         x->ex_flags |= EXFLAG_CRITICAL;
 432                         break;
 433                         }
 434                 }
 435         x->ex_flags |= EXFLAG_SET;
 436 }
 437
 438 /* CA checks common to all purposes
 439  * return codes:
 440  * 0 not a CA
 441  * 1 is a CA
 442  * 2 basicConstraints absent so "maybe" a CA
 443  * 3 basicConstraints absent but self signed V1.
 444  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 445  */
 446
 447 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 448 #define ku_reject(x, usage) \
 449         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 450 #define xku_reject(x, usage) \
 451         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 452 #define ns_reject(x, usage) \
 453         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 454
 455 static int check_ca(const X509 *x)
 456 {
 457         /* keyUsage if present should allow cert signing */
 458         if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
 459         if(x->ex_flags & EXFLAG_BCONS) {
 460                 if(x->ex_flags & EXFLAG_CA) return 1;
 461                 /* If basicConstraints says not a CA then say so */
 462                 else return 0;
 463         } else {
 464                 /* we support V1 roots for...  uh, I don't really know why. */
 465                 if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
 466                 /* If key usage present it must have certSign so tolerate it */
 467                 else if (x->ex_flags & EXFLAG_KUSAGE) return 4;
 468                 /* Older certificates could have Netscape-specific CA types */
 469                 else if (x->ex_flags & EXFLAG_NSCERT
 470                          && x->ex_nscert & NS_ANY_CA) return 5;
 471                 /* can this still be regarded a CA certificate?  I doubt it */
 472                 return 0;
 473         }
 474 }
 475
 476 int X509_check_ca(X509 *x)
 477 {
 478         if(!(x->ex_flags & EXFLAG_SET)) {
 479                 CRYPTO_w_lock(CRYPTO_LOCK_X509);
 480                 x509v3_cache_extensions(x);
 481                 CRYPTO_w_unlock(CRYPTO_LOCK_X509);
 482         }
 483
 484         return check_ca(x);
 485 }
 486
 487 /* Check SSL CA: common checks for SSL client and server */
 488 static int check_ssl_ca(const X509 *x)
 489 {
 490         int ca_ret;
 491         ca_ret = check_ca(x);
 492         if(!ca_ret) return 0;
 493         /* check nsCertType if present */
 494         if(ca_ret != 5 || x->ex_nscert & NS_SSL_CA) return ca_ret;
 495         else return 0;
 496 }
 497
 498
 499 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
 500 {
 501         if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
 502         if(ca) return check_ssl_ca(x);
 503         /* We need to do digital signatures with it */
 504         if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
 505         /* nsCertType if present should allow SSL client use */
 506         if(ns_reject(x, NS_SSL_CLIENT)) return 0;
 507         return 1;
 508 }
 509
 510 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 511 {
 512         if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
 513         if(ca) return check_ssl_ca(x);
 514
 515         if(ns_reject(x, NS_SSL_SERVER)) return 0;
 516         /* Now as for keyUsage: we'll at least need to sign OR encipher */
 517         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
 518
 519         return 1;
 520
 521 }
 522
 523 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 524 {
 525         int ret;
 526         ret = check_purpose_ssl_server(xp, x, ca);
 527         if(!ret || ca) return ret;
 528         /* We need to encipher or Netscape complains */
 529         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 530         return ret;
 531 }
 532
 533 /* common S/MIME checks */
 534 static int purpose_smime(const X509 *x, int ca)
 535 {
 536         if(xku_reject(x,XKU_SMIME)) return 0;
 537         if(ca) {
 538                 int ca_ret;
 539                 ca_ret = check_ca(x);
 540                 if(!ca_ret) return 0;
 541                 /* check nsCertType if present */
 542                 if(ca_ret != 5 || x->ex_nscert & NS_SMIME_CA) return ca_ret;
 543                 else return 0;
 544         }
 545         if(x->ex_flags & EXFLAG_NSCERT) {
 546                 if(x->ex_nscert & NS_SMIME) return 1;
 547                 /* Workaround for some buggy certificates */
 548                 if(x->ex_nscert & NS_SSL_CLIENT) return 2;
 549                 return 0;
 550         }
 551         return 1;
 552 }
 553
 554 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 555 {
 556         int ret;
 557         ret = purpose_smime(x, ca);
 558         if(!ret || ca) return ret;
 559         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
 560         return ret;
 561 }
 562
 563 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
 564 {
 565         int ret;
 566         ret = purpose_smime(x, ca);
 567         if(!ret || ca) return ret;
 568         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 569         return ret;
 570 }
 571
 572 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 573 {
 574         if(ca) {
 575                 int ca_ret;
 576                 if((ca_ret = check_ca(x)) != 2) return ca_ret;
 577                 else return 0;
 578         }
 579         if(ku_reject(x, KU_CRL_SIGN)) return 0;
 580         return 1;
 581 }
 582
 583 /* OCSP helper: this is *not* a full OCSP check. It just checks that
 584  * each CA is valid. Additional checks must be made on the chain.
 585  */
 586
 587 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 588 {
 589         /* Must be a valid CA.  Should we really support the "I don't know"
 590            value (2)? */
 591         if(ca) return check_ca(x);
 592         /* leaf certificate is checked in OCSP_verify() */
 593         return 1;
 594 }
 595
 596 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 597 {
 598         return 1;
 599 }
 600
 601 /* Various checks to see if one certificate issued the second.
 602  * This can be used to prune a set of possible issuer certificates
 603  * which have been looked up using some simple method such as by
 604  * subject name.
 605  * These are:
 606  * 1. Check issuer_name(subject) == subject_name(issuer)
 607  * 2. If akid(subject) exists check it matches issuer
 608  * 3. If key_usage(issuer) exists check it supports certificate signing
 609  * returns 0 for OK, positive for reason for mismatch, reasons match
 610  * codes for X509_verify_cert()
 611  */
 612
 613 int X509_check_issued(X509 *issuer, X509 *subject)
 614 {
 615         if(X509_NAME_cmp(X509_get_subject_name(issuer),
 616                         X509_get_issuer_name(subject)))
 617                                 return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 618         x509v3_cache_extensions(issuer);
 619         x509v3_cache_extensions(subject);
 620         if(subject->akid) {
 621                 /* Check key ids (if present) */
 622                 if(subject->akid->keyid && issuer->skid &&
 623                  ASN1_OCTET_STRING_cmp(subject->akid->keyid, issuer->skid) )
 624                                 return X509_V_ERR_AKID_SKID_MISMATCH;
 625                 /* Check serial number */
 626                 if(subject->akid->serial &&
 627                         ASN1_INTEGER_cmp(X509_get_serialNumber(issuer),
 628                                                 subject->akid->serial))
 629                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 630                 /* Check issuer name */
 631                 if(subject->akid->issuer) {
 632                         /* Ugh, for some peculiar reason AKID includes
 633                          * SEQUENCE OF GeneralName. So look for a DirName.
 634                          * There may be more than one but we only take any
 635                          * notice of the first.
 636                          */
 637                         GENERAL_NAMES *gens;
 638                         GENERAL_NAME *gen;
 639                         X509_NAME *nm = NULL;
 640                         int i;
 641                         gens = subject->akid->issuer;
 642                         for(i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 643                                 gen = sk_GENERAL_NAME_value(gens, i);
 644                                 if(gen->type == GEN_DIRNAME) {
 645                                         nm = gen->d.dirn;
 646                                         break;
 647                                 }
 648                         }
 649                         if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 650                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 651                 }
 652         }
 653         if(subject->ex_flags & EXFLAG_PROXY)
 654                 {
 655                 if(ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 656                         return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 657                 }
 658         else if(ku_reject(issuer, KU_KEY_CERT_SIGN))
 659                 return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 660         return X509_V_OK;
 661 }
 662