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 check_purpose_timestamp_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         {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0, check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign", NULL},
  92 };
  93
  94 #define X509_PURPOSE_COUNT (sizeof(xstandard)/sizeof(X509_PURPOSE))
  95
  96 IMPLEMENT_STACK_OF(X509_PURPOSE)
  97
  98 static STACK_OF(X509_PURPOSE) *xptable = NULL;
  99
 100 static int xp_cmp(const X509_PURPOSE * const *a,
 101                 const X509_PURPOSE * const *b)
 102 {
 103         return (*a)->purpose - (*b)->purpose;
 104 }
 105
 106 /* As much as I'd like to make X509_check_purpose use a "const" X509*
 107  * I really can't because it does recalculate hashes and do other non-const
 108  * things. */
 109 int X509_check_purpose(X509 *x, int id, int ca)
 110 {
 111         int idx;
 112         const X509_PURPOSE *pt;
 113         if(!(x->ex_flags & EXFLAG_SET)) {
 114                 CRYPTO_w_lock(CRYPTO_LOCK_X509);
 115                 x509v3_cache_extensions(x);
 116                 CRYPTO_w_unlock(CRYPTO_LOCK_X509);
 117         }
 118         if(id == -1) return 1;
 119         idx = X509_PURPOSE_get_by_id(id);
 120         if(idx == -1) return -1;
 121         pt = X509_PURPOSE_get0(idx);
 122         return pt->check_purpose(pt, x, ca);
 123 }
 124
 125 int X509_PURPOSE_set(int *p, int purpose)
 126 {
 127         if(X509_PURPOSE_get_by_id(purpose) == -1) {
 128                 X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
 129                 return 0;
 130         }
 131         *p = purpose;
 132         return 1;
 133 }
 134
 135 int X509_PURPOSE_get_count(void)
 136 {
 137         if(!xptable) return X509_PURPOSE_COUNT;
 138         return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
 139 }
 140
 141 X509_PURPOSE * X509_PURPOSE_get0(int idx)
 142 {
 143         if(idx < 0) return NULL;
 144         if(idx < (int)X509_PURPOSE_COUNT) return xstandard + idx;
 145         return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
 146 }
 147
 148 int X509_PURPOSE_get_by_sname(char *sname)
 149 {
 150         int i;
 151         X509_PURPOSE *xptmp;
 152         for(i = 0; i < X509_PURPOSE_get_count(); i++) {
 153                 xptmp = X509_PURPOSE_get0(i);
 154                 if(!strcmp(xptmp->sname, sname)) return i;
 155         }
 156         return -1;
 157 }
 158
 159 int X509_PURPOSE_get_by_id(int purpose)
 160 {
 161         X509_PURPOSE tmp;
 162         int idx;
 163         if((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
 164                 return purpose - X509_PURPOSE_MIN;
 165         tmp.purpose = purpose;
 166         if(!xptable) return -1;
 167         idx = sk_X509_PURPOSE_find(xptable, &tmp);
 168         if(idx == -1) return -1;
 169         return idx + X509_PURPOSE_COUNT;
 170 }
 171
 172 int X509_PURPOSE_add(int id, int trust, int flags,
 173                         int (*ck)(const X509_PURPOSE *, const X509 *, int),
 174                                         char *name, char *sname, void *arg)
 175 {
 176         int idx;
 177         X509_PURPOSE *ptmp;
 178         /* This is set according to what we change: application can't set it */
 179         flags &= ~X509_PURPOSE_DYNAMIC;
 180         /* This will always be set for application modified trust entries */
 181         flags |= X509_PURPOSE_DYNAMIC_NAME;
 182         /* Get existing entry if any */
 183         idx = X509_PURPOSE_get_by_id(id);
 184         /* Need a new entry */
 185         if(idx == -1) {
 186                 if(!(ptmp = OPENSSL_malloc(sizeof(X509_PURPOSE)))) {
 187                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 188                         return 0;
 189                 }
 190                 ptmp->flags = X509_PURPOSE_DYNAMIC;
 191         } else ptmp = X509_PURPOSE_get0(idx);
 192
 193         /* OPENSSL_free existing name if dynamic */
 194         if(ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
 195                 OPENSSL_free(ptmp->name);
 196                 OPENSSL_free(ptmp->sname);
 197         }
 198         /* dup supplied name */
 199         ptmp->name = BUF_strdup(name);
 200         ptmp->sname = BUF_strdup(sname);
 201         if(!ptmp->name || !ptmp->sname) {
 202                 X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 203                 return 0;
 204         }
 205         /* Keep the dynamic flag of existing entry */
 206         ptmp->flags &= X509_PURPOSE_DYNAMIC;
 207         /* Set all other flags */
 208         ptmp->flags |= flags;
 209
 210         ptmp->purpose = id;
 211         ptmp->trust = trust;
 212         ptmp->check_purpose = ck;
 213         ptmp->usr_data = arg;
 214
 215         /* If its a new entry manage the dynamic table */
 216         if(idx == -1) {
 217                 if(!xptable && !(xptable = sk_X509_PURPOSE_new(xp_cmp))) {
 218                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 219                         return 0;
 220                 }
 221                 if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
 222                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
 223                         return 0;
 224                 }
 225         }
 226         return 1;
 227 }
 228
 229 static void xptable_free(X509_PURPOSE *p)
 230         {
 231         if(!p) return;
 232         if (p->flags & X509_PURPOSE_DYNAMIC)
 233                 {
 234                 if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
 235                         OPENSSL_free(p->name);
 236                         OPENSSL_free(p->sname);
 237                 }
 238                 OPENSSL_free(p);
 239                 }
 240         }
 241
 242 void X509_PURPOSE_cleanup(void)
 243 {
 244         unsigned int i;
 245         sk_X509_PURPOSE_pop_free(xptable, xptable_free);
 246         for(i = 0; i < X509_PURPOSE_COUNT; i++) xptable_free(xstandard + i);
 247         xptable = NULL;
 248 }
 249
 250 int X509_PURPOSE_get_id(X509_PURPOSE *xp)
 251 {
 252         return xp->purpose;
 253 }
 254
 255 char *X509_PURPOSE_get0_name(X509_PURPOSE *xp)
 256 {
 257         return xp->name;
 258 }
 259
 260 char *X509_PURPOSE_get0_sname(X509_PURPOSE *xp)
 261 {
 262         return xp->sname;
 263 }
 264
 265 int X509_PURPOSE_get_trust(X509_PURPOSE *xp)
 266 {
 267         return xp->trust;
 268 }
 269
 270 static int nid_cmp(int *a, int *b)
 271         {
 272         return *a - *b;
 273         }
 274
 275 int X509_supported_extension(X509_EXTENSION *ex)
 276         {
 277         /* This table is a list of the NIDs of supported extensions:
 278          * that is those which are used by the verify process. If
 279          * an extension is critical and doesn't appear in this list
 280          * then the verify process will normally reject the certificate.
 281          * The list must be kept in numerical order because it will be
 282          * searched using bsearch.
 283          */
 284
 285         static int supported_nids[] = {
 286                 NID_netscape_cert_type, /* 71 */
 287                 NID_key_usage,          /* 83 */
 288                 NID_subject_alt_name,   /* 85 */
 289                 NID_basic_constraints,  /* 87 */
 290                 NID_certificate_policies, /* 89 */
 291                 NID_ext_key_usage,      /* 126 */
 292 #ifndef OPENSSL_NO_RFC3779
 293                 NID_sbgp_ipAddrBlock,   /* 290 */
 294                 NID_sbgp_autonomousSysNum, /* 291 */
 295 #endif
 296                 NID_policy_constraints, /* 401 */
 297                 NID_proxyCertInfo       /* 663 */
 298         };
 299
 300         int ex_nid;
 301
 302         ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 303
 304         if (ex_nid == NID_undef)
 305                 return 0;
 306
 307         if (OBJ_bsearch((char *)&ex_nid, (char *)supported_nids,
 308                 sizeof(supported_nids)/sizeof(int), sizeof(int),
 309                 (int (*)(const void *, const void *))nid_cmp))
 310                 return 1;
 311         return 0;
 312         }
 313
 314
 315 static void x509v3_cache_extensions(X509 *x)
 316 {
 317         BASIC_CONSTRAINTS *bs;
 318         PROXY_CERT_INFO_EXTENSION *pci;
 319         ASN1_BIT_STRING *usage;
 320         ASN1_BIT_STRING *ns;
 321         EXTENDED_KEY_USAGE *extusage;
 322         X509_EXTENSION *ex;
 323
 324         int i;
 325         if(x->ex_flags & EXFLAG_SET) return;
 326 #ifndef OPENSSL_NO_SHA
 327         X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 328 #endif
 329         /* Does subject name match issuer ? */
 330         if(!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
 331                          x->ex_flags |= EXFLAG_SI;
 332         /* V1 should mean no extensions ... */
 333         if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
 334         /* Handle basic constraints */
 335         if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 336                 if(bs->ca) x->ex_flags |= EXFLAG_CA;
 337                 if(bs->pathlen) {
 338                         if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 339                                                 || !bs->ca) {
 340                                 x->ex_flags |= EXFLAG_INVALID;
 341                                 x->ex_pathlen = 0;
 342                         } else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 343                 } else x->ex_pathlen = -1;
 344                 BASIC_CONSTRAINTS_free(bs);
 345                 x->ex_flags |= EXFLAG_BCONS;
 346         }
 347         /* Handle proxy certificates */
 348         if((pci=X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
 349                 if (x->ex_flags & EXFLAG_CA
 350                     || X509_get_ext_by_NID(x, NID_subject_alt_name, 0) >= 0
 351                     || X509_get_ext_by_NID(x, NID_issuer_alt_name, 0) >= 0) {
 352                         x->ex_flags |= EXFLAG_INVALID;
 353                 }
 354                 if (pci->pcPathLengthConstraint) {
 355                         x->ex_pcpathlen =
 356                                 ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 357                 } else x->ex_pcpathlen = -1;
 358                 PROXY_CERT_INFO_EXTENSION_free(pci);
 359                 x->ex_flags |= EXFLAG_PROXY;
 360         }
 361         /* Handle key usage */
 362         if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 363                 if(usage->length > 0) {
 364                         x->ex_kusage = usage->data[0];
 365                         if(usage->length > 1)
 366                                 x->ex_kusage |= usage->data[1] << 8;
 367                 } else x->ex_kusage = 0;
 368                 x->ex_flags |= EXFLAG_KUSAGE;
 369                 ASN1_BIT_STRING_free(usage);
 370         }
 371         x->ex_xkusage = 0;
 372         if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 373                 x->ex_flags |= EXFLAG_XKUSAGE;
 374                 for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 375                         switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
 376                                 case NID_server_auth:
 377                                 x->ex_xkusage |= XKU_SSL_SERVER;
 378                                 break;
 379
 380                                 case NID_client_auth:
 381                                 x->ex_xkusage |= XKU_SSL_CLIENT;
 382                                 break;
 383
 384                                 case NID_email_protect:
 385                                 x->ex_xkusage |= XKU_SMIME;
 386                                 break;
 387
 388                                 case NID_code_sign:
 389                                 x->ex_xkusage |= XKU_CODE_SIGN;
 390                                 break;
 391
 392                                 case NID_ms_sgc:
 393                                 case NID_ns_sgc:
 394                                 x->ex_xkusage |= XKU_SGC;
 395                                 break;
 396
 397                                 case NID_OCSP_sign:
 398                                 x->ex_xkusage |= XKU_OCSP_SIGN;
 399                                 break;
 400
 401                                 case NID_time_stamp:
 402                                 x->ex_xkusage |= XKU_TIMESTAMP;
 403                                 break;
 404
 405                                 case NID_dvcs:
 406                                 x->ex_xkusage |= XKU_DVCS;
 407                                 break;
 408                         }
 409                 }
 410                 sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 411         }
 412
 413         if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 414                 if(ns->length > 0) x->ex_nscert = ns->data[0];
 415                 else x->ex_nscert = 0;
 416                 x->ex_flags |= EXFLAG_NSCERT;
 417                 ASN1_BIT_STRING_free(ns);
 418         }
 419         x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 420         x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 421         x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL);
 422 #ifndef OPENSSL_NO_RFC3779
 423         x->rfc3779_addr =X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
 424         x->rfc3779_asid =X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
 425                                           NULL, NULL);
 426 #endif
 427         for (i = 0; i < X509_get_ext_count(x); i++)
 428                 {
 429                 ex = X509_get_ext(x, i);
 430                 if (!X509_EXTENSION_get_critical(ex))
 431                         continue;
 432                 if (!X509_supported_extension(ex))
 433                         {
 434                         x->ex_flags |= EXFLAG_CRITICAL;
 435                         break;
 436                         }
 437                 }
 438         x->ex_flags |= EXFLAG_SET;
 439 }
 440
 441 /* CA checks common to all purposes
 442  * return codes:
 443  * 0 not a CA
 444  * 1 is a CA
 445  * 2 basicConstraints absent so "maybe" a CA
 446  * 3 basicConstraints absent but self signed V1.
 447  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 448  */
 449
 450 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 451 #define ku_reject(x, usage) \
 452         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 453 #define xku_reject(x, usage) \
 454         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 455 #define ns_reject(x, usage) \
 456         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 457
 458 static int check_ca(const X509 *x)
 459 {
 460         /* keyUsage if present should allow cert signing */
 461         if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
 462         if(x->ex_flags & EXFLAG_BCONS) {
 463                 if(x->ex_flags & EXFLAG_CA) return 1;
 464                 /* If basicConstraints says not a CA then say so */
 465                 else return 0;
 466         } else {
 467                 /* we support V1 roots for...  uh, I don't really know why. */
 468                 if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
 469                 /* If key usage present it must have certSign so tolerate it */
 470                 else if (x->ex_flags & EXFLAG_KUSAGE) return 4;
 471                 /* Older certificates could have Netscape-specific CA types */
 472                 else if (x->ex_flags & EXFLAG_NSCERT
 473                          && x->ex_nscert & NS_ANY_CA) return 5;
 474                 /* can this still be regarded a CA certificate?  I doubt it */
 475                 return 0;
 476         }
 477 }
 478
 479 int X509_check_ca(X509 *x)
 480 {
 481         if(!(x->ex_flags & EXFLAG_SET)) {
 482                 CRYPTO_w_lock(CRYPTO_LOCK_X509);
 483                 x509v3_cache_extensions(x);
 484                 CRYPTO_w_unlock(CRYPTO_LOCK_X509);
 485         }
 486
 487         return check_ca(x);
 488 }
 489
 490 /* Check SSL CA: common checks for SSL client and server */
 491 static int check_ssl_ca(const X509 *x)
 492 {
 493         int ca_ret;
 494         ca_ret = check_ca(x);
 495         if(!ca_ret) return 0;
 496         /* check nsCertType if present */
 497         if(ca_ret != 5 || x->ex_nscert & NS_SSL_CA) return ca_ret;
 498         else return 0;
 499 }
 500
 501
 502 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
 503 {
 504         if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
 505         if(ca) return check_ssl_ca(x);
 506         /* We need to do digital signatures with it */
 507         if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
 508         /* nsCertType if present should allow SSL client use */
 509         if(ns_reject(x, NS_SSL_CLIENT)) return 0;
 510         return 1;
 511 }
 512
 513 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 514 {
 515         if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
 516         if(ca) return check_ssl_ca(x);
 517
 518         if(ns_reject(x, NS_SSL_SERVER)) return 0;
 519         /* Now as for keyUsage: we'll at least need to sign OR encipher */
 520         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
 521
 522         return 1;
 523
 524 }
 525
 526 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 527 {
 528         int ret;
 529         ret = check_purpose_ssl_server(xp, x, ca);
 530         if(!ret || ca) return ret;
 531         /* We need to encipher or Netscape complains */
 532         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 533         return ret;
 534 }
 535
 536 /* common S/MIME checks */
 537 static int purpose_smime(const X509 *x, int ca)
 538 {
 539         if(xku_reject(x,XKU_SMIME)) return 0;
 540         if(ca) {
 541                 int ca_ret;
 542                 ca_ret = check_ca(x);
 543                 if(!ca_ret) return 0;
 544                 /* check nsCertType if present */
 545                 if(ca_ret != 5 || x->ex_nscert & NS_SMIME_CA) return ca_ret;
 546                 else return 0;
 547         }
 548         if(x->ex_flags & EXFLAG_NSCERT) {
 549                 if(x->ex_nscert & NS_SMIME) return 1;
 550                 /* Workaround for some buggy certificates */
 551                 if(x->ex_nscert & NS_SSL_CLIENT) return 2;
 552                 return 0;
 553         }
 554         return 1;
 555 }
 556
 557 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 558 {
 559         int ret;
 560         ret = purpose_smime(x, ca);
 561         if(!ret || ca) return ret;
 562         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
 563         return ret;
 564 }
 565
 566 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
 567 {
 568         int ret;
 569         ret = purpose_smime(x, ca);
 570         if(!ret || ca) return ret;
 571         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 572         return ret;
 573 }
 574
 575 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 576 {
 577         if(ca) {
 578                 int ca_ret;
 579                 if((ca_ret = check_ca(x)) != 2) return ca_ret;
 580                 else return 0;
 581         }
 582         if(ku_reject(x, KU_CRL_SIGN)) return 0;
 583         return 1;
 584 }
 585
 586 /* OCSP helper: this is *not* a full OCSP check. It just checks that
 587  * each CA is valid. Additional checks must be made on the chain.
 588  */
 589
 590 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 591 {
 592         /* Must be a valid CA.  Should we really support the "I don't know"
 593            value (2)? */
 594         if(ca) return check_ca(x);
 595         /* leaf certificate is checked in OCSP_verify() */
 596         return 1;
 597 }
 598
 599 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
 600                                         int ca)
 601 {
 602         int i_ext;
 603
 604         /* If ca is true we must return if this is a valid CA certificate. */
 605         if (ca) return check_ca(x);
 606
 607         /*
 608          * Check the optional key usage field:
 609          * if Key Usage is present, it must be one of digitalSignature
 610          * and/or nonRepudiation (other values are not consistent and shall
 611          * be rejected).
 612          */
 613         if ((x->ex_flags & EXFLAG_KUSAGE)
 614             && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
 615                 !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
 616                 return 0;
 617
 618         /* Only time stamp key usage is permitted and it's required. */
 619         if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
 620                 return 0;
 621
 622         /* Extended Key Usage MUST be critical */
 623         i_ext = X509_get_ext_by_NID((X509 *) x, NID_ext_key_usage, 0);
 624         if (i_ext >= 0)
 625                 {
 626                 X509_EXTENSION *ext = X509_get_ext((X509 *) x, i_ext);
 627                 if (!X509_EXTENSION_get_critical(ext))
 628                         return 0;
 629                 }
 630
 631         return 1;
 632 }
 633
 634 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 635 {
 636         return 1;
 637 }
 638
 639 /* Various checks to see if one certificate issued the second.
 640  * This can be used to prune a set of possible issuer certificates
 641  * which have been looked up using some simple method such as by
 642  * subject name.
 643  * These are:
 644  * 1. Check issuer_name(subject) == subject_name(issuer)
 645  * 2. If akid(subject) exists check it matches issuer
 646  * 3. If key_usage(issuer) exists check it supports certificate signing
 647  * returns 0 for OK, positive for reason for mismatch, reasons match
 648  * codes for X509_verify_cert()
 649  */
 650
 651 int X509_check_issued(X509 *issuer, X509 *subject)
 652 {
 653         if(X509_NAME_cmp(X509_get_subject_name(issuer),
 654                         X509_get_issuer_name(subject)))
 655                                 return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 656         x509v3_cache_extensions(issuer);
 657         x509v3_cache_extensions(subject);
 658
 659         if(subject->akid)
 660                 {
 661                 int ret = X509_check_akid(issuer, subject->akid);
 662                 if (ret != X509_V_OK)
 663                         return ret;
 664                 }
 665
 666         if(subject->ex_flags & EXFLAG_PROXY)
 667                 {
 668                 if(ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 669                         return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 670                 }
 671         else if(ku_reject(issuer, KU_KEY_CERT_SIGN))
 672                 return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 673         return X509_V_OK;
 674 }
 675
 676 int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
 677         {
 678
 679         if(!akid)
 680                 return X509_V_OK;
 681
 682         /* Check key ids (if present) */
 683         if(akid->keyid && issuer->skid &&
 684                  ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid) )
 685                                 return X509_V_ERR_AKID_SKID_MISMATCH;
 686         /* Check serial number */
 687         if(akid->serial &&
 688                 ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
 689                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 690         /* Check issuer name */
 691         if(akid->issuer)
 692                 {
 693                 /* Ugh, for some peculiar reason AKID includes
 694                  * SEQUENCE OF GeneralName. So look for a DirName.
 695                  * There may be more than one but we only take any
 696                  * notice of the first.
 697                  */
 698                 GENERAL_NAMES *gens;
 699                 GENERAL_NAME *gen;
 700                 X509_NAME *nm = NULL;
 701                 int i;
 702                 gens = akid->issuer;
 703                 for(i = 0; i < sk_GENERAL_NAME_num(gens); i++)
 704                         {
 705                         gen = sk_GENERAL_NAME_value(gens, i);
 706                         if(gen->type == GEN_DIRNAME)
 707                                 {
 708                                 nm = gen->d.dirn;
 709                                 break;
 710                                 }
 711                         }
 712                 if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 713                         return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 714                 }
 715         return X509_V_OK;
 716         }
 717