src/third_party/boringssl/src/crypto/x509v3/v3_purp.c

   1 /* v3_purp.c */
   2 /* Written by Dr Stephen N Henson (steve@openssl.org) 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 #include <stdio.h>
  58
  59 #include <openssl/buf.h>
  60 #include <openssl/err.h>
  61 #include <openssl/digest.h>
  62 #include <openssl/mem.h>
  63 #include <openssl/obj.h>
  64 #include <openssl/x509_vfy.h>
  65 #include <openssl/x509v3.h>
  66
  67
  68 static void x509v3_cache_extensions(X509 *x);
  69
  70 static int check_ssl_ca(const X509 *x);
  71 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca);
  72 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
  73 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
  74 static int purpose_smime(const X509 *x, int ca);
  75 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
  76 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca);
  77 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
  78 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
  79 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
  80 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
  81
  82 static int xp_cmp(const X509_PURPOSE **a, const X509_PURPOSE **b);
  83 static void xptable_free(X509_PURPOSE *p);
  84
  85 static X509_PURPOSE xstandard[] = {
  86         {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0, check_purpose_ssl_client, (char *) "SSL client", (char *) "sslclient", NULL},
  87         {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ssl_server, (char *) "SSL server", (char *) "sslserver", NULL},
  88         {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ns_ssl_server, (char *) "Netscape SSL server", (char *) "nssslserver", NULL},
  89         {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign, (char *) "S/MIME signing", (char *) "smimesign", NULL},
  90         {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0, check_purpose_smime_encrypt, (char *) "S/MIME encryption", (char *) "smimeencrypt", NULL},
  91         {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign, (char *) "CRL signing", (char *) "crlsign", NULL},
  92         {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, (char *) "Any Purpose", (char *) "any", NULL},
  93         {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper, (char *) "OCSP helper", (char *) "ocsphelper", NULL},
  94         {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0, check_purpose_timestamp_sign, (char *) "Time Stamp signing", (char *) "timestampsign", NULL},
  95 };
  96
  97 #define X509_PURPOSE_COUNT (sizeof(xstandard)/sizeof(X509_PURPOSE))
  98
  99 static STACK_OF(X509_PURPOSE) *xptable = NULL;
 100
 101 static int xp_cmp(const X509_PURPOSE **a, const X509_PURPOSE **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                 OPENSSL_PUT_ERROR(X509V3, 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         size_t idx;
 163
 164         if((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
 165                 return purpose - X509_PURPOSE_MIN;
 166         tmp.purpose = purpose;
 167         if(!xptable) return -1;
 168
 169         if (!sk_X509_PURPOSE_find(xptable, &idx, &tmp))
 170                 return -1;
 171         return idx + X509_PURPOSE_COUNT;
 172 }
 173
 174 int X509_PURPOSE_add(int id, int trust, int flags,
 175                         int (*ck)(const X509_PURPOSE *, const X509 *, int),
 176                                         char *name, char *sname, void *arg)
 177 {
 178         int idx;
 179         X509_PURPOSE *ptmp;
 180         /* This is set according to what we change: application can't set it */
 181         flags &= ~X509_PURPOSE_DYNAMIC;
 182         /* This will always be set for application modified trust entries */
 183         flags |= X509_PURPOSE_DYNAMIC_NAME;
 184         /* Get existing entry if any */
 185         idx = X509_PURPOSE_get_by_id(id);
 186         /* Need a new entry */
 187         if(idx == -1) {
 188                 if(!(ptmp = OPENSSL_malloc(sizeof(X509_PURPOSE)))) {
 189                         OPENSSL_PUT_ERROR(X509V3, X509_PURPOSE_add, ERR_R_MALLOC_FAILURE);
 190                         return 0;
 191                 }
 192                 ptmp->flags = X509_PURPOSE_DYNAMIC;
 193         } else ptmp = X509_PURPOSE_get0(idx);
 194
 195         /* OPENSSL_free existing name if dynamic */
 196         if(ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
 197                 OPENSSL_free(ptmp->name);
 198                 OPENSSL_free(ptmp->sname);
 199         }
 200         /* dup supplied name */
 201         ptmp->name = BUF_strdup(name);
 202         ptmp->sname = BUF_strdup(sname);
 203         if(!ptmp->name || !ptmp->sname) {
 204                 OPENSSL_PUT_ERROR(X509V3, X509_PURPOSE_add, ERR_R_MALLOC_FAILURE);
 205                 return 0;
 206         }
 207         /* Keep the dynamic flag of existing entry */
 208         ptmp->flags &= X509_PURPOSE_DYNAMIC;
 209         /* Set all other flags */
 210         ptmp->flags |= flags;
 211
 212         ptmp->purpose = id;
 213         ptmp->trust = trust;
 214         ptmp->check_purpose = ck;
 215         ptmp->usr_data = arg;
 216
 217         /* If its a new entry manage the dynamic table */
 218         if(idx == -1) {
 219                 if(!xptable && !(xptable = sk_X509_PURPOSE_new(xp_cmp))) {
 220                         OPENSSL_PUT_ERROR(X509V3, X509_PURPOSE_add, ERR_R_MALLOC_FAILURE);
 221                         return 0;
 222                 }
 223                 if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
 224                         OPENSSL_PUT_ERROR(X509V3, X509_PURPOSE_add, ERR_R_MALLOC_FAILURE);
 225                         return 0;
 226                 }
 227         }
 228         return 1;
 229 }
 230
 231 static void xptable_free(X509_PURPOSE *p)
 232         {
 233         if(!p) return;
 234         if (p->flags & X509_PURPOSE_DYNAMIC)
 235                 {
 236                 if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
 237                         OPENSSL_free(p->name);
 238                         OPENSSL_free(p->sname);
 239                 }
 240                 OPENSSL_free(p);
 241                 }
 242         }
 243
 244 void X509_PURPOSE_cleanup(void)
 245 {
 246         unsigned int i;
 247         sk_X509_PURPOSE_pop_free(xptable, xptable_free);
 248         for(i = 0; i < X509_PURPOSE_COUNT; i++) xptable_free(xstandard + i);
 249         xptable = NULL;
 250 }
 251
 252 int X509_PURPOSE_get_id(X509_PURPOSE *xp)
 253 {
 254         return xp->purpose;
 255 }
 256
 257 char *X509_PURPOSE_get0_name(X509_PURPOSE *xp)
 258 {
 259         return xp->name;
 260 }
 261
 262 char *X509_PURPOSE_get0_sname(X509_PURPOSE *xp)
 263 {
 264         return xp->sname;
 265 }
 266
 267 int X509_PURPOSE_get_trust(X509_PURPOSE *xp)
 268 {
 269         return xp->trust;
 270 }
 271
 272 static int nid_cmp(const void *void_a, const void *void_b)
 273         {
 274         const int *a = void_a, *b = void_b;
 275
 276         return *a - *b;
 277         }
 278
 279 int X509_supported_extension(X509_EXTENSION *ex)
 280         {
 281         /* This table is a list of the NIDs of supported extensions:
 282          * that is those which are used by the verify process. If
 283          * an extension is critical and doesn't appear in this list
 284          * then the verify process will normally reject the certificate.
 285          * The list must be kept in numerical order because it will be
 286          * searched using bsearch.
 287          */
 288
 289         static const int supported_nids[] = {
 290                 NID_netscape_cert_type, /* 71 */
 291                 NID_key_usage,          /* 83 */
 292                 NID_subject_alt_name,   /* 85 */
 293                 NID_basic_constraints,  /* 87 */
 294                 NID_certificate_policies, /* 89 */
 295                 NID_ext_key_usage,      /* 126 */
 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 = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 304
 305         if (ex_nid == NID_undef)
 306                 return 0;
 307
 308         if (bsearch(&ex_nid, supported_nids, sizeof(supported_nids)/sizeof(int), sizeof(int), nid_cmp) != NULL)
 309                 return 1;
 310         return 0;
 311         }
 312
 313 static void setup_dp(X509 *x, DIST_POINT *dp)
 314         {
 315         X509_NAME *iname = NULL;
 316         size_t i;
 317         if (dp->reasons)
 318                 {
 319                 if (dp->reasons->length > 0)
 320                         dp->dp_reasons = dp->reasons->data[0];
 321                 if (dp->reasons->length > 1)
 322                         dp->dp_reasons |= (dp->reasons->data[1] << 8);
 323                 dp->dp_reasons &= CRLDP_ALL_REASONS;
 324                 }
 325         else
 326                 dp->dp_reasons = CRLDP_ALL_REASONS;
 327         if (!dp->distpoint || (dp->distpoint->type != 1))
 328                 return;
 329         for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++)
 330                 {
 331                 GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
 332                 if (gen->type == GEN_DIRNAME)
 333                         {
 334                         iname = gen->d.directoryName;
 335                         break;
 336                         }
 337                 }
 338         if (!iname)
 339                 iname = X509_get_issuer_name(x);
 340
 341         DIST_POINT_set_dpname(dp->distpoint, iname);
 342
 343         }
 344
 345 static void setup_crldp(X509 *x)
 346         {
 347         size_t i;
 348         x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL);
 349         for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++)
 350                 setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
 351         }
 352
 353 static void x509v3_cache_extensions(X509 *x)
 354 {
 355         BASIC_CONSTRAINTS *bs;
 356         PROXY_CERT_INFO_EXTENSION *pci;
 357         ASN1_BIT_STRING *usage;
 358         ASN1_BIT_STRING *ns;
 359         EXTENDED_KEY_USAGE *extusage;
 360         X509_EXTENSION *ex;
 361         size_t i;
 362         int j;
 363         if(x->ex_flags & EXFLAG_SET) return;
 364         X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 365         /* V1 should mean no extensions ... */
 366         if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
 367         /* Handle basic constraints */
 368         if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 369                 if(bs->ca) x->ex_flags |= EXFLAG_CA;
 370                 if(bs->pathlen) {
 371                         if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 372                                                 || !bs->ca) {
 373                                 x->ex_flags |= EXFLAG_INVALID;
 374                                 x->ex_pathlen = 0;
 375                         } else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 376                 } else x->ex_pathlen = -1;
 377                 BASIC_CONSTRAINTS_free(bs);
 378                 x->ex_flags |= EXFLAG_BCONS;
 379         }
 380         /* Handle proxy certificates */
 381         if((pci=X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
 382                 if (x->ex_flags & EXFLAG_CA
 383                     || X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
 384                     || X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
 385                         x->ex_flags |= EXFLAG_INVALID;
 386                 }
 387                 if (pci->pcPathLengthConstraint) {
 388                         x->ex_pcpathlen =
 389                                 ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 390                 } else x->ex_pcpathlen = -1;
 391                 PROXY_CERT_INFO_EXTENSION_free(pci);
 392                 x->ex_flags |= EXFLAG_PROXY;
 393         }
 394         /* Handle key usage */
 395         if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 396                 if(usage->length > 0) {
 397                         x->ex_kusage = usage->data[0];
 398                         if(usage->length > 1)
 399                                 x->ex_kusage |= usage->data[1] << 8;
 400                 } else x->ex_kusage = 0;
 401                 x->ex_flags |= EXFLAG_KUSAGE;
 402                 ASN1_BIT_STRING_free(usage);
 403         }
 404         x->ex_xkusage = 0;
 405         if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 406                 x->ex_flags |= EXFLAG_XKUSAGE;
 407                 for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 408                         switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
 409                                 case NID_server_auth:
 410                                 x->ex_xkusage |= XKU_SSL_SERVER;
 411                                 break;
 412
 413                                 case NID_client_auth:
 414                                 x->ex_xkusage |= XKU_SSL_CLIENT;
 415                                 break;
 416
 417                                 case NID_email_protect:
 418                                 x->ex_xkusage |= XKU_SMIME;
 419                                 break;
 420
 421                                 case NID_code_sign:
 422                                 x->ex_xkusage |= XKU_CODE_SIGN;
 423                                 break;
 424
 425                                 case NID_ms_sgc:
 426                                 case NID_ns_sgc:
 427                                 x->ex_xkusage |= XKU_SGC;
 428                                 break;
 429
 430                                 case NID_OCSP_sign:
 431                                 x->ex_xkusage |= XKU_OCSP_SIGN;
 432                                 break;
 433
 434                                 case NID_time_stamp:
 435                                 x->ex_xkusage |= XKU_TIMESTAMP;
 436                                 break;
 437
 438                                 case NID_dvcs:
 439                                 x->ex_xkusage |= XKU_DVCS;
 440                                 break;
 441
 442                                 case NID_anyExtendedKeyUsage:
 443                                 x->ex_xkusage |= XKU_ANYEKU;
 444                                 break;
 445                         }
 446                 }
 447                 sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 448         }
 449
 450         if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 451                 if(ns->length > 0) x->ex_nscert = ns->data[0];
 452                 else x->ex_nscert = 0;
 453                 x->ex_flags |= EXFLAG_NSCERT;
 454                 ASN1_BIT_STRING_free(ns);
 455         }
 456         x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 457         x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 458         /* Does subject name match issuer ? */
 459         if(!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
 460                         {
 461                         x->ex_flags |= EXFLAG_SI;
 462                         /* If SKID matches AKID also indicate self signed */
 463                         if (X509_check_akid(x, x->akid) == X509_V_OK)
 464                                 x->ex_flags |= EXFLAG_SS;
 465                         }
 466         x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
 467         x->nc = X509_get_ext_d2i(x, NID_name_constraints, &j, NULL);
 468         if (!x->nc && (j != -1))
 469                 x->ex_flags |= EXFLAG_INVALID;
 470         setup_crldp(x);
 471
 472         for (j = 0; j < X509_get_ext_count(x); j++)
 473                 {
 474                 ex = X509_get_ext(x, j);
 475                 if (OBJ_obj2nid(X509_EXTENSION_get_object(ex))
 476                                         == NID_freshest_crl)
 477                         x->ex_flags |= EXFLAG_FRESHEST;
 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 or key agreement */
 555         if(ku_reject(x,KU_DIGITAL_SIGNATURE|KU_KEY_AGREEMENT)) 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 /* Key usage needed for TLS/SSL server: digital signature, encipherment or
 561  * key agreement. The ssl code can check this more thoroughly for individual
 562  * key types.
 563  */
 564 #define KU_TLS \
 565         KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT
 566
 567 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 568 {
 569         if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
 570         if(ca) return check_ssl_ca(x);
 571
 572         if(ns_reject(x, NS_SSL_SERVER)) return 0;
 573         if(ku_reject(x, KU_TLS)) return 0;
 574
 575         return 1;
 576
 577 }
 578
 579 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
 580 {
 581         int ret;
 582         ret = check_purpose_ssl_server(xp, x, ca);
 583         if(!ret || ca) return ret;
 584         /* We need to encipher or Netscape complains */
 585         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 586         return ret;
 587 }
 588
 589 /* common S/MIME checks */
 590 static int purpose_smime(const X509 *x, int ca)
 591 {
 592         if(xku_reject(x,XKU_SMIME)) return 0;
 593         if(ca) {
 594                 int ca_ret;
 595                 ca_ret = check_ca(x);
 596                 if(!ca_ret) return 0;
 597                 /* check nsCertType if present */
 598                 if(ca_ret != 5 || x->ex_nscert & NS_SMIME_CA) return ca_ret;
 599                 else return 0;
 600         }
 601         if(x->ex_flags & EXFLAG_NSCERT) {
 602                 if(x->ex_nscert & NS_SMIME) return 1;
 603                 /* Workaround for some buggy certificates */
 604                 if(x->ex_nscert & NS_SSL_CLIENT) return 2;
 605                 return 0;
 606         }
 607         return 1;
 608 }
 609
 610 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 611 {
 612         int ret;
 613         ret = purpose_smime(x, ca);
 614         if(!ret || ca) return ret;
 615         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
 616         return ret;
 617 }
 618
 619 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
 620 {
 621         int ret;
 622         ret = purpose_smime(x, ca);
 623         if(!ret || ca) return ret;
 624         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
 625         return ret;
 626 }
 627
 628 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 629 {
 630         if(ca) {
 631                 int ca_ret;
 632                 if((ca_ret = check_ca(x)) != 2) return ca_ret;
 633                 else return 0;
 634         }
 635         if(ku_reject(x, KU_CRL_SIGN)) return 0;
 636         return 1;
 637 }
 638
 639 /* OCSP helper: this is *not* a full OCSP check. It just checks that
 640  * each CA is valid. Additional checks must be made on the chain.
 641  */
 642
 643 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 644 {
 645         /* Must be a valid CA.  Should we really support the "I don't know"
 646            value (2)? */
 647         if(ca) return check_ca(x);
 648         /* leaf certificate is checked in OCSP_verify() */
 649         return 1;
 650 }
 651
 652 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
 653                                         int ca)
 654 {
 655         int i_ext;
 656
 657         /* If ca is true we must return if this is a valid CA certificate. */
 658         if (ca) return check_ca(x);
 659
 660         /*
 661          * Check the optional key usage field:
 662          * if Key Usage is present, it must be one of digitalSignature
 663          * and/or nonRepudiation (other values are not consistent and shall
 664          * be rejected).
 665          */
 666         if ((x->ex_flags & EXFLAG_KUSAGE)
 667             && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
 668                 !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
 669                 return 0;
 670
 671         /* Only time stamp key usage is permitted and it's required. */
 672         if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
 673                 return 0;
 674
 675         /* Extended Key Usage MUST be critical */
 676         i_ext = X509_get_ext_by_NID((X509 *) x, NID_ext_key_usage, -1);
 677         if (i_ext >= 0)
 678                 {
 679                 X509_EXTENSION *ext = X509_get_ext((X509 *) x, i_ext);
 680                 if (!X509_EXTENSION_get_critical(ext))
 681                         return 0;
 682                 }
 683
 684         return 1;
 685 }
 686
 687 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 688 {
 689         return 1;
 690 }
 691
 692 /* Various checks to see if one certificate issued the second.
 693  * This can be used to prune a set of possible issuer certificates
 694  * which have been looked up using some simple method such as by
 695  * subject name.
 696  * These are:
 697  * 1. Check issuer_name(subject) == subject_name(issuer)
 698  * 2. If akid(subject) exists check it matches issuer
 699  * 3. If key_usage(issuer) exists check it supports certificate signing
 700  * returns 0 for OK, positive for reason for mismatch, reasons match
 701  * codes for X509_verify_cert()
 702  */
 703
 704 int X509_check_issued(X509 *issuer, X509 *subject)
 705 {
 706         if(X509_NAME_cmp(X509_get_subject_name(issuer),
 707                         X509_get_issuer_name(subject)))
 708                                 return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 709         x509v3_cache_extensions(issuer);
 710         x509v3_cache_extensions(subject);
 711
 712         if(subject->akid)
 713                 {
 714                 int ret = X509_check_akid(issuer, subject->akid);
 715                 if (ret != X509_V_OK)
 716                         return ret;
 717                 }
 718
 719         if(subject->ex_flags & EXFLAG_PROXY)
 720                 {
 721                 if(ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 722                         return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 723                 }
 724         else if(ku_reject(issuer, KU_KEY_CERT_SIGN))
 725                 return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 726         return X509_V_OK;
 727 }
 728
 729 int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
 730         {
 731
 732         if(!akid)
 733                 return X509_V_OK;
 734
 735         /* Check key ids (if present) */
 736         if(akid->keyid && issuer->skid &&
 737                  ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid) )
 738                                 return X509_V_ERR_AKID_SKID_MISMATCH;
 739         /* Check serial number */
 740         if(akid->serial &&
 741                 ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
 742                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 743         /* Check issuer name */
 744         if(akid->issuer)
 745                 {
 746                 /* Ugh, for some peculiar reason AKID includes
 747                  * SEQUENCE OF GeneralName. So look for a DirName.
 748                  * There may be more than one but we only take any
 749                  * notice of the first.
 750                  */
 751                 GENERAL_NAMES *gens;
 752                 GENERAL_NAME *gen;
 753                 X509_NAME *nm = NULL;
 754                 size_t i;
 755                 gens = akid->issuer;
 756                 for(i = 0; i < sk_GENERAL_NAME_num(gens); i++)
 757                         {
 758                         gen = sk_GENERAL_NAME_value(gens, i);
 759                         if(gen->type == GEN_DIRNAME)
 760                                 {
 761                                 nm = gen->d.dirn;
 762                                 break;
 763                                 }
 764                         }
 765                 if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 766                         return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 767                 }
 768         return X509_V_OK;
 769         }
 770