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                 NID_name_constraints,   /* 666 */
 299                 NID_policy_mappings,    /* 747 */
 300                 NID_inhibit_any_policy  /* 748 */
 301         };
 302
 303         int ex_nid;
 304
 305         ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 306
 307         if (ex_nid == NID_undef)
 308                 return 0;
 309
 310         if (OBJ_bsearch((char *)&ex_nid, (char *)supported_nids,
 311                 sizeof(supported_nids)/sizeof(int), sizeof(int),
 312                 (int (*)(const void *, const void *))nid_cmp))
 313                 return 1;
 314         return 0;
 315         }
 316
 317 static void setup_dp(X509 *x, DIST_POINT *dp)
 318         {
 319         X509_NAME *iname = NULL;
 320         int i;
 321         if (dp->reasons)
 322                 {
 323                 if (dp->reasons->length > 0)
 324                         dp->dp_reasons = dp->reasons->data[0];
 325                 if (dp->reasons->length > 1)
 326                         dp->dp_reasons |= (dp->reasons->data[1] << 8);
 327                 dp->dp_reasons &= CRLDP_ALL_REASONS;
 328                 }
 329         else
 330                 dp->dp_reasons = CRLDP_ALL_REASONS;
 331         if (!dp->distpoint || (dp->distpoint->type != 1))
 332                 return;
 333         for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++)
 334                 {
 335                 GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
 336                 if (gen->type == GEN_DIRNAME)
 337                         {
 338                         iname = gen->d.directoryName;
 339                         break;
 340                         }
 341                 }
 342         if (!iname)
 343                 iname = X509_get_issuer_name(x);
 344
 345         DIST_POINT_set_dpname(dp->distpoint, iname);
 346
 347         }
 348
 349 static void setup_crldp(X509 *x)
 350         {
 351         int i;
 352         x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL);
 353         for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++)
 354                 setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
 355         }
 356
 357 static void x509v3_cache_extensions(X509 *x)
 358 {
 359         BASIC_CONSTRAINTS *bs;
 360         PROXY_CERT_INFO_EXTENSION *pci;
 361         ASN1_BIT_STRING *usage;
 362         ASN1_BIT_STRING *ns;
 363         EXTENDED_KEY_USAGE *extusage;
 364         X509_EXTENSION *ex;
 365
 366         int i;
 367         if(x->ex_flags & EXFLAG_SET) return;
 368 #ifndef OPENSSL_NO_SHA
 369         X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 370 #endif
 371         /* Does subject name match issuer ? */
 372         if(!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
 373                          x->ex_flags |= EXFLAG_SI;
 374         /* V1 should mean no extensions ... */
 375         if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
 376         /* Handle basic constraints */
 377         if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 378                 if(bs->ca) x->ex_flags |= EXFLAG_CA;
 379                 if(bs->pathlen) {
 380                         if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 381                                                 || !bs->ca) {
 382                                 x->ex_flags |= EXFLAG_INVALID;
 383                                 x->ex_pathlen = 0;
 384                         } else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 385                 } else x->ex_pathlen = -1;
 386                 BASIC_CONSTRAINTS_free(bs);
 387                 x->ex_flags |= EXFLAG_BCONS;
 388         }
 389         /* Handle proxy certificates */
 390         if((pci=X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
 391                 if (x->ex_flags & EXFLAG_CA
 392                     || X509_get_ext_by_NID(x, NID_subject_alt_name, 0) >= 0
 393                     || X509_get_ext_by_NID(x, NID_issuer_alt_name, 0) >= 0) {
 394                         x->ex_flags |= EXFLAG_INVALID;
 395                 }
 396                 if (pci->pcPathLengthConstraint) {
 397                         x->ex_pcpathlen =
 398                                 ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 399                 } else x->ex_pcpathlen = -1;
 400                 PROXY_CERT_INFO_EXTENSION_free(pci);
 401                 x->ex_flags |= EXFLAG_PROXY;
 402         }
 403         /* Handle key usage */
 404         if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 405                 if(usage->length > 0) {
 406                         x->ex_kusage = usage->data[0];
 407                         if(usage->length > 1)
 408                                 x->ex_kusage |= usage->data[1] << 8;
 409                 } else x->ex_kusage = 0;
 410                 x->ex_flags |= EXFLAG_KUSAGE;
 411                 ASN1_BIT_STRING_free(usage);
 412         }
 413         x->ex_xkusage = 0;
 414         if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 415                 x->ex_flags |= EXFLAG_XKUSAGE;
 416                 for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 417                         switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
 418                                 case NID_server_auth:
 419                                 x->ex_xkusage |= XKU_SSL_SERVER;
 420                                 break;
 421
 422                                 case NID_client_auth:
 423                                 x->ex_xkusage |= XKU_SSL_CLIENT;
 424                                 break;
 425
 426                                 case NID_email_protect:
 427                                 x->ex_xkusage |= XKU_SMIME;
 428                                 break;
 429
 430                                 case NID_code_sign:
 431                                 x->ex_xkusage |= XKU_CODE_SIGN;
 432                                 break;
 433
 434                                 case NID_ms_sgc:
 435                                 case NID_ns_sgc:
 436                                 x->ex_xkusage |= XKU_SGC;
 437                                 break;
 438
 439                                 case NID_OCSP_sign:
 440                                 x->ex_xkusage |= XKU_OCSP_SIGN;
 441                                 break;
 442
 443                                 case NID_time_stamp:
 444                                 x->ex_xkusage |= XKU_TIMESTAMP;
 445                                 break;
 446
 447                                 case NID_dvcs:
 448                                 x->ex_xkusage |= XKU_DVCS;
 449                                 break;
 450                         }
 451                 }
 452                 sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 453         }
 454
 455         if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 456                 if(ns->length > 0) x->ex_nscert = ns->data[0];
 457                 else x->ex_nscert = 0;
 458                 x->ex_flags |= EXFLAG_NSCERT;
 459                 ASN1_BIT_STRING_free(ns);
 460         }
 461         x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 462         x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 463         x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
 464         x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
 465         if (!x->nc && (i != -1))
 466                 x->ex_flags |= EXFLAG_INVALID;
 467         setup_crldp(x);
 468
 469
 470 #ifndef OPENSSL_NO_RFC3779
 471         x->rfc3779_addr =X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
 472         x->rfc3779_asid =X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
 473                                           NULL, NULL);
 474 #endif
 475         for (i = 0; i < X509_get_ext_count(x); i++)
 476                 {
 477                 ex = X509_get_ext(x, i);
 478                 if (!X509_EXTENSION_get_critical(ex))
 479                         continue;
 480                 if (!X509_supported_extension(ex))
 481                         {
 482                         x->ex_flags |= EXFLAG_CRITICAL;
 483                         break;
 484                         }
 485                 }
 486         x->ex_flags |= EXFLAG_SET;
 487 }
 488
 489 /* CA checks common to all purposes
 490  * return codes:
 491  * 0 not a CA
 492  * 1 is a CA
 493  * 2 basicConstraints absent so "maybe" a CA
 494  * 3 basicConstraints absent but self signed V1.
 495  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 496  */
 497
 498 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 499 #define ku_reject(x, usage) \
 500         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 501 #define xku_reject(x, usage) \
 502         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 503 #define ns_reject(x, usage) \
 504         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 505
 506 static int check_ca(const X509 *x)
 507 {
 508         /* keyUsage if present should allow cert signing */
 509         if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
 510         if(x->ex_flags & EXFLAG_BCONS) {
 511                 if(x->ex_flags & EXFLAG_CA) return 1;
 512                 /* If basicConstraints says not a CA then say so */
 513                 else return 0;
 514         } else {
 515                 /* we support V1 roots for...  uh, I don't really know why. */
 516                 if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
 517                 /* If key usage present it must have certSign so tolerate it */
 518                 else if (x->ex_flags & EXFLAG_KUSAGE) return 4;
 519                 /* Older certificates could have Netscape-specific CA types */
 520                 else if (x->ex_flags & EXFLAG_NSCERT
 521                          && x->ex_nscert & NS_ANY_CA) return 5;
 522                 /* can this still be regarded a CA certificate?  I doubt it */
 523                 return 0;
 524         }
 525 }
 526
 527 int X509_check_ca(X509 *x)
 528 {
 529         if(!(x->ex_flags & EXFLAG_SET)) {
 530                 CRYPTO_w_lock(CRYPTO_LOCK_X509);
 531                 x509v3_cache_extensions(x);
 532                 CRYPTO_w_unlock(CRYPTO_LOCK_X509);
 533         }
 534
 535         return check_ca(x);
 536 }
 537
 538 /* Check SSL CA: common checks for SSL client and server */
 539 static int check_ssl_ca(const X509 *x)
 540 {
 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_SSL_CA) return ca_ret;
 546         else return 0;
 547 }
 548
 549
 550 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
 551 {
 552         if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
 553         if(ca) return check_ssl_ca(x);
 554         /* We need to do digital signatures with it */
 555         if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
 556         /* nsCertType if present should allow SSL client use */
 557         if(ns_reject(x, NS_SSL_CLIENT)) return 0;
 558         return 1;
 559 }
 560
 561 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 562 {
 563         if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
 564         if(ca) return check_ssl_ca(x);
 565
 566         if(ns_reject(x, NS_SSL_SERVER)) return 0;
 567         /* Now as for keyUsage: we'll at least need to sign OR encipher */
 568         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
 569
 570         return 1;
 571
 572 }
 573
 574 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 575 {
 576         int ret;
 577         ret = check_purpose_ssl_server(xp, x, ca);
 578         if(!ret || ca) return ret;
 579         /* We need to encipher or Netscape complains */
 580         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 581         return ret;
 582 }
 583
 584 /* common S/MIME checks */
 585 static int purpose_smime(const X509 *x, int ca)
 586 {
 587         if(xku_reject(x,XKU_SMIME)) return 0;
 588         if(ca) {
 589                 int ca_ret;
 590                 ca_ret = check_ca(x);
 591                 if(!ca_ret) return 0;
 592                 /* check nsCertType if present */
 593                 if(ca_ret != 5 || x->ex_nscert & NS_SMIME_CA) return ca_ret;
 594                 else return 0;
 595         }
 596         if(x->ex_flags & EXFLAG_NSCERT) {
 597                 if(x->ex_nscert & NS_SMIME) return 1;
 598                 /* Workaround for some buggy certificates */
 599                 if(x->ex_nscert & NS_SSL_CLIENT) return 2;
 600                 return 0;
 601         }
 602         return 1;
 603 }
 604
 605 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 606 {
 607         int ret;
 608         ret = purpose_smime(x, ca);
 609         if(!ret || ca) return ret;
 610         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
 611         return ret;
 612 }
 613
 614 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
 615 {
 616         int ret;
 617         ret = purpose_smime(x, ca);
 618         if(!ret || ca) return ret;
 619         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 620         return ret;
 621 }
 622
 623 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 624 {
 625         if(ca) {
 626                 int ca_ret;
 627                 if((ca_ret = check_ca(x)) != 2) return ca_ret;
 628                 else return 0;
 629         }
 630         if(ku_reject(x, KU_CRL_SIGN)) return 0;
 631         return 1;
 632 }
 633
 634 /* OCSP helper: this is *not* a full OCSP check. It just checks that
 635  * each CA is valid. Additional checks must be made on the chain.
 636  */
 637
 638 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 639 {
 640         /* Must be a valid CA.  Should we really support the "I don't know"
 641            value (2)? */
 642         if(ca) return check_ca(x);
 643         /* leaf certificate is checked in OCSP_verify() */
 644         return 1;
 645 }
 646
 647 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
 648                                         int ca)
 649 {
 650         int i_ext;
 651
 652         /* If ca is true we must return if this is a valid CA certificate. */
 653         if (ca) return check_ca(x);
 654
 655         /*
 656          * Check the optional key usage field:
 657          * if Key Usage is present, it must be one of digitalSignature
 658          * and/or nonRepudiation (other values are not consistent and shall
 659          * be rejected).
 660          */
 661         if ((x->ex_flags & EXFLAG_KUSAGE)
 662             && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
 663                 !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
 664                 return 0;
 665
 666         /* Only time stamp key usage is permitted and it's required. */
 667         if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
 668                 return 0;
 669
 670         /* Extended Key Usage MUST be critical */
 671         i_ext = X509_get_ext_by_NID((X509 *) x, NID_ext_key_usage, 0);
 672         if (i_ext >= 0)
 673                 {
 674                 X509_EXTENSION *ext = X509_get_ext((X509 *) x, i_ext);
 675                 if (!X509_EXTENSION_get_critical(ext))
 676                         return 0;
 677                 }
 678
 679         return 1;
 680 }
 681
 682 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 683 {
 684         return 1;
 685 }
 686
 687 /* Various checks to see if one certificate issued the second.
 688  * This can be used to prune a set of possible issuer certificates
 689  * which have been looked up using some simple method such as by
 690  * subject name.
 691  * These are:
 692  * 1. Check issuer_name(subject) == subject_name(issuer)
 693  * 2. If akid(subject) exists check it matches issuer
 694  * 3. If key_usage(issuer) exists check it supports certificate signing
 695  * returns 0 for OK, positive for reason for mismatch, reasons match
 696  * codes for X509_verify_cert()
 697  */
 698
 699 int X509_check_issued(X509 *issuer, X509 *subject)
 700 {
 701         if(X509_NAME_cmp(X509_get_subject_name(issuer),
 702                         X509_get_issuer_name(subject)))
 703                                 return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 704         x509v3_cache_extensions(issuer);
 705         x509v3_cache_extensions(subject);
 706
 707         if(subject->akid)
 708                 {
 709                 int ret = X509_check_akid(issuer, subject->akid);
 710                 if (ret != X509_V_OK)
 711                         return ret;
 712                 }
 713
 714         if(subject->ex_flags & EXFLAG_PROXY)
 715                 {
 716                 if(ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 717                         return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 718                 }
 719         else if(ku_reject(issuer, KU_KEY_CERT_SIGN))
 720                 return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 721         return X509_V_OK;
 722 }
 723
 724 int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
 725         {
 726
 727         if(!akid)
 728                 return X509_V_OK;
 729
 730         /* Check key ids (if present) */
 731         if(akid->keyid && issuer->skid &&
 732                  ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid) )
 733                                 return X509_V_ERR_AKID_SKID_MISMATCH;
 734         /* Check serial number */
 735         if(akid->serial &&
 736                 ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
 737                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 738         /* Check issuer name */
 739         if(akid->issuer)
 740                 {
 741                 /* Ugh, for some peculiar reason AKID includes
 742                  * SEQUENCE OF GeneralName. So look for a DirName.
 743                  * There may be more than one but we only take any
 744                  * notice of the first.
 745                  */
 746                 GENERAL_NAMES *gens;
 747                 GENERAL_NAME *gen;
 748                 X509_NAME *nm = NULL;
 749                 int i;
 750                 gens = akid->issuer;
 751                 for(i = 0; i < sk_GENERAL_NAME_num(gens); i++)
 752                         {
 753                         gen = sk_GENERAL_NAME_value(gens, i);
 754                         if(gen->type == GEN_DIRNAME)
 755                                 {
 756                                 nm = gen->d.dirn;
 757                                 break;
 758                                 }
 759                         }
 760                 if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 761                         return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 762                 }
 763         return X509_V_OK;
 764         }
 765