crypto/x509v3/v3_purp.c

   1 /*
   2  * Copyright 1999-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include "internal/numbers.h"
  13 #include <openssl/x509v3.h>
  14 #include <openssl/x509_vfy.h>
  15 #include "internal/x509_int.h"
  16
  17 static void x509v3_cache_extensions(X509 *x);
  18
  19 static int check_ssl_ca(const X509 *x);
  20 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
  21                                     int ca);
  22 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
  23                                     int ca);
  24 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
  25                                        int ca);
  26 static int purpose_smime(const X509 *x, int ca);
  27 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
  28                                     int ca);
  29 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
  30                                        int ca);
  31 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
  32                                   int ca);
  33 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
  34                                         int ca);
  35 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
  36 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
  37
  38 static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b);
  39 static void xptable_free(X509_PURPOSE *p);
  40
  41 static X509_PURPOSE xstandard[] = {
  42     {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0,
  43      check_purpose_ssl_client, "SSL client", "sslclient", NULL},
  44     {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
  45      check_purpose_ssl_server, "SSL server", "sslserver", NULL},
  46     {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
  47      check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
  48     {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign,
  49      "S/MIME signing", "smimesign", NULL},
  50     {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0,
  51      check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
  52     {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign,
  53      "CRL signing", "crlsign", NULL},
  54     {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any",
  55      NULL},
  56     {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper,
  57      "OCSP helper", "ocsphelper", NULL},
  58     {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0,
  59      check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign",
  60      NULL},
  61 };
  62
  63 #define X509_PURPOSE_COUNT OSSL_NELEM(xstandard)
  64
  65 static STACK_OF(X509_PURPOSE) *xptable = NULL;
  66
  67 static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b)
  68 {
  69     return (*a)->purpose - (*b)->purpose;
  70 }
  71
  72 /*
  73  * As much as I'd like to make X509_check_purpose use a "const" X509* I
  74  * really can't because it does recalculate hashes and do other non-const
  75  * things.
  76  */
  77 int X509_check_purpose(X509 *x, int id, int ca)
  78 {
  79     int idx;
  80     const X509_PURPOSE *pt;
  81     if (!(x->ex_flags & EXFLAG_SET)) {
  82         CRYPTO_THREAD_write_lock(x->lock);
  83         x509v3_cache_extensions(x);
  84         CRYPTO_THREAD_unlock(x->lock);
  85     }
  86     /* Return if side-effect only call */
  87     if (id == -1)
  88         return 1;
  89     idx = X509_PURPOSE_get_by_id(id);
  90     if (idx == -1)
  91         return -1;
  92     pt = X509_PURPOSE_get0(idx);
  93     return pt->check_purpose(pt, x, ca);
  94 }
  95
  96 int X509_PURPOSE_set(int *p, int purpose)
  97 {
  98     if (X509_PURPOSE_get_by_id(purpose) == -1) {
  99         X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
 100         return 0;
 101     }
 102     *p = purpose;
 103     return 1;
 104 }
 105
 106 int X509_PURPOSE_get_count(void)
 107 {
 108     if (!xptable)
 109         return X509_PURPOSE_COUNT;
 110     return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
 111 }
 112
 113 X509_PURPOSE *X509_PURPOSE_get0(int idx)
 114 {
 115     if (idx < 0)
 116         return NULL;
 117     if (idx < (int)X509_PURPOSE_COUNT)
 118         return xstandard + idx;
 119     return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
 120 }
 121
 122 int X509_PURPOSE_get_by_sname(char *sname)
 123 {
 124     int i;
 125     X509_PURPOSE *xptmp;
 126     for (i = 0; i < X509_PURPOSE_get_count(); i++) {
 127         xptmp = X509_PURPOSE_get0(i);
 128         if (strcmp(xptmp->sname, sname) == 0)
 129             return i;
 130     }
 131     return -1;
 132 }
 133
 134 int X509_PURPOSE_get_by_id(int purpose)
 135 {
 136     X509_PURPOSE tmp;
 137     int idx;
 138     if ((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
 139         return purpose - X509_PURPOSE_MIN;
 140     tmp.purpose = purpose;
 141     if (!xptable)
 142         return -1;
 143     idx = sk_X509_PURPOSE_find(xptable, &tmp);
 144     if (idx == -1)
 145         return -1;
 146     return idx + X509_PURPOSE_COUNT;
 147 }
 148
 149 int X509_PURPOSE_add(int id, int trust, int flags,
 150                      int (*ck) (const X509_PURPOSE *, const X509 *, int),
 151                      char *name, char *sname, void *arg)
 152 {
 153     int idx;
 154     X509_PURPOSE *ptmp;
 155     /*
 156      * This is set according to what we change: application can't set it
 157      */
 158     flags &= ~X509_PURPOSE_DYNAMIC;
 159     /* This will always be set for application modified trust entries */
 160     flags |= X509_PURPOSE_DYNAMIC_NAME;
 161     /* Get existing entry if any */
 162     idx = X509_PURPOSE_get_by_id(id);
 163     /* Need a new entry */
 164     if (idx == -1) {
 165         if ((ptmp = OPENSSL_malloc(sizeof(*ptmp))) == NULL) {
 166             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 167             return 0;
 168         }
 169         ptmp->flags = X509_PURPOSE_DYNAMIC;
 170     } else
 171         ptmp = X509_PURPOSE_get0(idx);
 172
 173     /* OPENSSL_free existing name if dynamic */
 174     if (ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
 175         OPENSSL_free(ptmp->name);
 176         OPENSSL_free(ptmp->sname);
 177     }
 178     /* dup supplied name */
 179     ptmp->name = OPENSSL_strdup(name);
 180     ptmp->sname = OPENSSL_strdup(sname);
 181     if (!ptmp->name || !ptmp->sname) {
 182         X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 183         goto err;
 184     }
 185     /* Keep the dynamic flag of existing entry */
 186     ptmp->flags &= X509_PURPOSE_DYNAMIC;
 187     /* Set all other flags */
 188     ptmp->flags |= flags;
 189
 190     ptmp->purpose = id;
 191     ptmp->trust = trust;
 192     ptmp->check_purpose = ck;
 193     ptmp->usr_data = arg;
 194
 195     /* If its a new entry manage the dynamic table */
 196     if (idx == -1) {
 197         if (xptable == NULL
 198             && (xptable = sk_X509_PURPOSE_new(xp_cmp)) == NULL) {
 199             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 200             goto err;
 201         }
 202         if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
 203             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 204             goto err;
 205         }
 206     }
 207     return 1;
 208  err:
 209     if (idx == -1) {
 210         OPENSSL_free(ptmp->name);
 211         OPENSSL_free(ptmp->sname);
 212         OPENSSL_free(ptmp);
 213     }
 214     return 0;
 215 }
 216
 217 static void xptable_free(X509_PURPOSE *p)
 218 {
 219     if (!p)
 220         return;
 221     if (p->flags & X509_PURPOSE_DYNAMIC) {
 222         if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
 223             OPENSSL_free(p->name);
 224             OPENSSL_free(p->sname);
 225         }
 226         OPENSSL_free(p);
 227     }
 228 }
 229
 230 void X509_PURPOSE_cleanup(void)
 231 {
 232     unsigned int i;
 233     sk_X509_PURPOSE_pop_free(xptable, xptable_free);
 234     for (i = 0; i < X509_PURPOSE_COUNT; i++)
 235         xptable_free(xstandard + i);
 236     xptable = NULL;
 237 }
 238
 239 int X509_PURPOSE_get_id(X509_PURPOSE *xp)
 240 {
 241     return xp->purpose;
 242 }
 243
 244 char *X509_PURPOSE_get0_name(X509_PURPOSE *xp)
 245 {
 246     return xp->name;
 247 }
 248
 249 char *X509_PURPOSE_get0_sname(X509_PURPOSE *xp)
 250 {
 251     return xp->sname;
 252 }
 253
 254 int X509_PURPOSE_get_trust(X509_PURPOSE *xp)
 255 {
 256     return xp->trust;
 257 }
 258
 259 static int nid_cmp(const int *a, const int *b)
 260 {
 261     return *a - *b;
 262 }
 263
 264 DECLARE_OBJ_BSEARCH_CMP_FN(int, int, nid);
 265 IMPLEMENT_OBJ_BSEARCH_CMP_FN(int, int, nid);
 266
 267 int X509_supported_extension(X509_EXTENSION *ex)
 268 {
 269     /*
 270      * This table is a list of the NIDs of supported extensions: that is
 271      * those which are used by the verify process. If an extension is
 272      * critical and doesn't appear in this list then the verify process will
 273      * normally reject the certificate. The list must be kept in numerical
 274      * order because it will be searched using bsearch.
 275      */
 276
 277     static const int supported_nids[] = {
 278         NID_netscape_cert_type, /* 71 */
 279         NID_key_usage,          /* 83 */
 280         NID_subject_alt_name,   /* 85 */
 281         NID_basic_constraints,  /* 87 */
 282         NID_certificate_policies, /* 89 */
 283         NID_ext_key_usage,      /* 126 */
 284 #ifndef OPENSSL_NO_RFC3779
 285         NID_sbgp_ipAddrBlock,   /* 290 */
 286         NID_sbgp_autonomousSysNum, /* 291 */
 287 #endif
 288         NID_policy_constraints, /* 401 */
 289         NID_proxyCertInfo,      /* 663 */
 290         NID_name_constraints,   /* 666 */
 291         NID_policy_mappings,    /* 747 */
 292         NID_inhibit_any_policy  /* 748 */
 293     };
 294
 295     int ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 296
 297     if (ex_nid == NID_undef)
 298         return 0;
 299
 300     if (OBJ_bsearch_nid(&ex_nid, supported_nids, OSSL_NELEM(supported_nids)))
 301         return 1;
 302     return 0;
 303 }
 304
 305 static void setup_dp(X509 *x, DIST_POINT *dp)
 306 {
 307     X509_NAME *iname = NULL;
 308     int i;
 309     if (dp->reasons) {
 310         if (dp->reasons->length > 0)
 311             dp->dp_reasons = dp->reasons->data[0];
 312         if (dp->reasons->length > 1)
 313             dp->dp_reasons |= (dp->reasons->data[1] << 8);
 314         dp->dp_reasons &= CRLDP_ALL_REASONS;
 315     } else
 316         dp->dp_reasons = CRLDP_ALL_REASONS;
 317     if (!dp->distpoint || (dp->distpoint->type != 1))
 318         return;
 319     for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
 320         GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
 321         if (gen->type == GEN_DIRNAME) {
 322             iname = gen->d.directoryName;
 323             break;
 324         }
 325     }
 326     if (!iname)
 327         iname = X509_get_issuer_name(x);
 328
 329     DIST_POINT_set_dpname(dp->distpoint, iname);
 330
 331 }
 332
 333 static void setup_crldp(X509 *x)
 334 {
 335     int i;
 336     x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL);
 337     for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++)
 338         setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
 339 }
 340
 341 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 342 #define ku_reject(x, usage) \
 343         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 344 #define xku_reject(x, usage) \
 345         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 346 #define ns_reject(x, usage) \
 347         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 348
 349 static void x509v3_cache_extensions(X509 *x)
 350 {
 351     BASIC_CONSTRAINTS *bs;
 352     PROXY_CERT_INFO_EXTENSION *pci;
 353     ASN1_BIT_STRING *usage;
 354     ASN1_BIT_STRING *ns;
 355     EXTENDED_KEY_USAGE *extusage;
 356     X509_EXTENSION *ex;
 357
 358     int i;
 359     if (x->ex_flags & EXFLAG_SET)
 360         return;
 361     X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 362     /* V1 should mean no extensions ... */
 363     if (!X509_get_version(x))
 364         x->ex_flags |= EXFLAG_V1;
 365     /* Handle basic constraints */
 366     if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 367         if (bs->ca)
 368             x->ex_flags |= EXFLAG_CA;
 369         if (bs->pathlen) {
 370             if ((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 371                 || !bs->ca) {
 372                 x->ex_flags |= EXFLAG_INVALID;
 373                 x->ex_pathlen = 0;
 374             } else
 375                 x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 376         } else
 377             x->ex_pathlen = -1;
 378         BASIC_CONSTRAINTS_free(bs);
 379         x->ex_flags |= EXFLAG_BCONS;
 380     }
 381     /* Handle proxy certificates */
 382     if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
 383         if (x->ex_flags & EXFLAG_CA
 384             || X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
 385             || X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
 386             x->ex_flags |= EXFLAG_INVALID;
 387         }
 388         if (pci->pcPathLengthConstraint) {
 389             x->ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 390         } else
 391             x->ex_pcpathlen = -1;
 392         PROXY_CERT_INFO_EXTENSION_free(pci);
 393         x->ex_flags |= EXFLAG_PROXY;
 394     }
 395     /* Handle key usage */
 396     if ((usage = X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 397         if (usage->length > 0) {
 398             x->ex_kusage = usage->data[0];
 399             if (usage->length > 1)
 400                 x->ex_kusage |= usage->data[1] << 8;
 401         } else
 402             x->ex_kusage = 0;
 403         x->ex_flags |= EXFLAG_KUSAGE;
 404         ASN1_BIT_STRING_free(usage);
 405     }
 406     x->ex_xkusage = 0;
 407     if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 408         x->ex_flags |= EXFLAG_XKUSAGE;
 409         for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 410             switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
 411             case NID_server_auth:
 412                 x->ex_xkusage |= XKU_SSL_SERVER;
 413                 break;
 414
 415             case NID_client_auth:
 416                 x->ex_xkusage |= XKU_SSL_CLIENT;
 417                 break;
 418
 419             case NID_email_protect:
 420                 x->ex_xkusage |= XKU_SMIME;
 421                 break;
 422
 423             case NID_code_sign:
 424                 x->ex_xkusage |= XKU_CODE_SIGN;
 425                 break;
 426
 427             case NID_ms_sgc:
 428             case NID_ns_sgc:
 429                 x->ex_xkusage |= XKU_SGC;
 430                 break;
 431
 432             case NID_OCSP_sign:
 433                 x->ex_xkusage |= XKU_OCSP_SIGN;
 434                 break;
 435
 436             case NID_time_stamp:
 437                 x->ex_xkusage |= XKU_TIMESTAMP;
 438                 break;
 439
 440             case NID_dvcs:
 441                 x->ex_xkusage |= XKU_DVCS;
 442                 break;
 443
 444             case NID_anyExtendedKeyUsage:
 445                 x->ex_xkusage |= XKU_ANYEKU;
 446                 break;
 447             }
 448         }
 449         sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 450     }
 451
 452     if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 453         if (ns->length > 0)
 454             x->ex_nscert = ns->data[0];
 455         else
 456             x->ex_nscert = 0;
 457         x->ex_flags |= EXFLAG_NSCERT;
 458         ASN1_BIT_STRING_free(ns);
 459     }
 460     x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 461     x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 462     /* Does subject name match issuer ? */
 463     if (!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x))) {
 464         x->ex_flags |= EXFLAG_SI;
 465         /* If SKID matches AKID also indicate self signed */
 466         if (X509_check_akid(x, x->akid) == X509_V_OK &&
 467             !ku_reject(x, KU_KEY_CERT_SIGN))
 468             x->ex_flags |= EXFLAG_SS;
 469     }
 470     x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
 471     x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
 472     if (!x->nc && (i != -1))
 473         x->ex_flags |= EXFLAG_INVALID;
 474     setup_crldp(x);
 475
 476 #ifndef OPENSSL_NO_RFC3779
 477     x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
 478     x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
 479                                        NULL, NULL);
 480 #endif
 481     for (i = 0; i < X509_get_ext_count(x); i++) {
 482         ex = X509_get_ext(x, i);
 483         if (OBJ_obj2nid(X509_EXTENSION_get_object(ex))
 484             == NID_freshest_crl)
 485             x->ex_flags |= EXFLAG_FRESHEST;
 486         if (!X509_EXTENSION_get_critical(ex))
 487             continue;
 488         if (!X509_supported_extension(ex)) {
 489             x->ex_flags |= EXFLAG_CRITICAL;
 490             break;
 491         }
 492     }
 493     x->ex_flags |= EXFLAG_SET;
 494 }
 495
 496 /*-
 497  * CA checks common to all purposes
 498  * return codes:
 499  * 0 not a CA
 500  * 1 is a CA
 501  * 2 basicConstraints absent so "maybe" a CA
 502  * 3 basicConstraints absent but self signed V1.
 503  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 504  */
 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))
 510         return 0;
 511     if (x->ex_flags & EXFLAG_BCONS) {
 512         if (x->ex_flags & EXFLAG_CA)
 513             return 1;
 514         /* If basicConstraints says not a CA then say so */
 515         else
 516             return 0;
 517     } else {
 518         /* we support V1 roots for...  uh, I don't really know why. */
 519         if ((x->ex_flags & V1_ROOT) == V1_ROOT)
 520             return 3;
 521         /*
 522          * If key usage present it must have certSign so tolerate it
 523          */
 524         else if (x->ex_flags & EXFLAG_KUSAGE)
 525             return 4;
 526         /* Older certificates could have Netscape-specific CA types */
 527         else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
 528             return 5;
 529         /* can this still be regarded a CA certificate?  I doubt it */
 530         return 0;
 531     }
 532 }
 533
 534 int X509_check_ca(X509 *x)
 535 {
 536     if (!(x->ex_flags & EXFLAG_SET)) {
 537         CRYPTO_THREAD_write_lock(x->lock);
 538         x509v3_cache_extensions(x);
 539         CRYPTO_THREAD_unlock(x->lock);
 540     }
 541
 542     return check_ca(x);
 543 }
 544
 545 /* Check SSL CA: common checks for SSL client and server */
 546 static int check_ssl_ca(const X509 *x)
 547 {
 548     int ca_ret;
 549     ca_ret = check_ca(x);
 550     if (!ca_ret)
 551         return 0;
 552     /* check nsCertType if present */
 553     if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
 554         return ca_ret;
 555     else
 556         return 0;
 557 }
 558
 559 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
 560                                     int ca)
 561 {
 562     if (xku_reject(x, XKU_SSL_CLIENT))
 563         return 0;
 564     if (ca)
 565         return check_ssl_ca(x);
 566     /* We need to do digital signatures or key agreement */
 567     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
 568         return 0;
 569     /* nsCertType if present should allow SSL client use */
 570     if (ns_reject(x, NS_SSL_CLIENT))
 571         return 0;
 572     return 1;
 573 }
 574
 575 /*
 576  * Key usage needed for TLS/SSL server: digital signature, encipherment or
 577  * key agreement. The ssl code can check this more thoroughly for individual
 578  * key types.
 579  */
 580 #define KU_TLS \
 581         KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT
 582
 583 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 584                                     int ca)
 585 {
 586     if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
 587         return 0;
 588     if (ca)
 589         return check_ssl_ca(x);
 590
 591     if (ns_reject(x, NS_SSL_SERVER))
 592         return 0;
 593     if (ku_reject(x, KU_TLS))
 594         return 0;
 595
 596     return 1;
 597
 598 }
 599
 600 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 601                                        int ca)
 602 {
 603     int ret;
 604     ret = check_purpose_ssl_server(xp, x, ca);
 605     if (!ret || ca)
 606         return ret;
 607     /* We need to encipher or Netscape complains */
 608     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 609         return 0;
 610     return ret;
 611 }
 612
 613 /* common S/MIME checks */
 614 static int purpose_smime(const X509 *x, int ca)
 615 {
 616     if (xku_reject(x, XKU_SMIME))
 617         return 0;
 618     if (ca) {
 619         int ca_ret;
 620         ca_ret = check_ca(x);
 621         if (!ca_ret)
 622             return 0;
 623         /* check nsCertType if present */
 624         if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
 625             return ca_ret;
 626         else
 627             return 0;
 628     }
 629     if (x->ex_flags & EXFLAG_NSCERT) {
 630         if (x->ex_nscert & NS_SMIME)
 631             return 1;
 632         /* Workaround for some buggy certificates */
 633         if (x->ex_nscert & NS_SSL_CLIENT)
 634             return 2;
 635         return 0;
 636     }
 637     return 1;
 638 }
 639
 640 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
 641                                     int ca)
 642 {
 643     int ret;
 644     ret = purpose_smime(x, ca);
 645     if (!ret || ca)
 646         return ret;
 647     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION))
 648         return 0;
 649     return ret;
 650 }
 651
 652 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
 653                                        int ca)
 654 {
 655     int ret;
 656     ret = purpose_smime(x, ca);
 657     if (!ret || ca)
 658         return ret;
 659     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 660         return 0;
 661     return ret;
 662 }
 663
 664 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
 665                                   int ca)
 666 {
 667     if (ca) {
 668         int ca_ret;
 669         if ((ca_ret = check_ca(x)) != 2)
 670             return ca_ret;
 671         else
 672             return 0;
 673     }
 674     if (ku_reject(x, KU_CRL_SIGN))
 675         return 0;
 676     return 1;
 677 }
 678
 679 /*
 680  * OCSP helper: this is *not* a full OCSP check. It just checks that each CA
 681  * is valid. Additional checks must be made on the chain.
 682  */
 683
 684 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 685 {
 686     /*
 687      * Must be a valid CA.  Should we really support the "I don't know" value
 688      * (2)?
 689      */
 690     if (ca)
 691         return check_ca(x);
 692     /* leaf certificate is checked in OCSP_verify() */
 693     return 1;
 694 }
 695
 696 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
 697                                         int ca)
 698 {
 699     int i_ext;
 700
 701     /* If ca is true we must return if this is a valid CA certificate. */
 702     if (ca)
 703         return check_ca(x);
 704
 705     /*
 706      * Check the optional key usage field:
 707      * if Key Usage is present, it must be one of digitalSignature
 708      * and/or nonRepudiation (other values are not consistent and shall
 709      * be rejected).
 710      */
 711     if ((x->ex_flags & EXFLAG_KUSAGE)
 712         && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
 713             !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
 714         return 0;
 715
 716     /* Only time stamp key usage is permitted and it's required. */
 717     if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
 718         return 0;
 719
 720     /* Extended Key Usage MUST be critical */
 721     i_ext = X509_get_ext_by_NID((X509 *)x, NID_ext_key_usage, -1);
 722     if (i_ext >= 0) {
 723         X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
 724         if (!X509_EXTENSION_get_critical(ext))
 725             return 0;
 726     }
 727
 728     return 1;
 729 }
 730
 731 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 732 {
 733     return 1;
 734 }
 735
 736 /*-
 737  * Various checks to see if one certificate issued the second.
 738  * This can be used to prune a set of possible issuer certificates
 739  * which have been looked up using some simple method such as by
 740  * subject name.
 741  * These are:
 742  * 1. Check issuer_name(subject) == subject_name(issuer)
 743  * 2. If akid(subject) exists check it matches issuer
 744  * 3. If key_usage(issuer) exists check it supports certificate signing
 745  * returns 0 for OK, positive for reason for mismatch, reasons match
 746  * codes for X509_verify_cert()
 747  */
 748
 749 int X509_check_issued(X509 *issuer, X509 *subject)
 750 {
 751     if (X509_NAME_cmp(X509_get_subject_name(issuer),
 752                       X509_get_issuer_name(subject)))
 753         return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 754     x509v3_cache_extensions(issuer);
 755     x509v3_cache_extensions(subject);
 756
 757     if (subject->akid) {
 758         int ret = X509_check_akid(issuer, subject->akid);
 759         if (ret != X509_V_OK)
 760             return ret;
 761     }
 762
 763     if (subject->ex_flags & EXFLAG_PROXY) {
 764         if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 765             return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 766     } else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
 767         return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 768     return X509_V_OK;
 769 }
 770
 771 int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
 772 {
 773
 774     if (!akid)
 775         return X509_V_OK;
 776
 777     /* Check key ids (if present) */
 778     if (akid->keyid && issuer->skid &&
 779         ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid))
 780         return X509_V_ERR_AKID_SKID_MISMATCH;
 781     /* Check serial number */
 782     if (akid->serial &&
 783         ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
 784         return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 785     /* Check issuer name */
 786     if (akid->issuer) {
 787         /*
 788          * Ugh, for some peculiar reason AKID includes SEQUENCE OF
 789          * GeneralName. So look for a DirName. There may be more than one but
 790          * we only take any notice of the first.
 791          */
 792         GENERAL_NAMES *gens;
 793         GENERAL_NAME *gen;
 794         X509_NAME *nm = NULL;
 795         int i;
 796         gens = akid->issuer;
 797         for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 798             gen = sk_GENERAL_NAME_value(gens, i);
 799             if (gen->type == GEN_DIRNAME) {
 800                 nm = gen->d.dirn;
 801                 break;
 802             }
 803         }
 804         if (nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 805             return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 806     }
 807     return X509_V_OK;
 808 }
 809
 810 uint32_t X509_get_extension_flags(X509 *x)
 811 {
 812     /* Call for side-effect of computing hash and caching extensions */
 813     X509_check_purpose(x, -1, -1);
 814     return x->ex_flags;
 815 }
 816
 817 uint32_t X509_get_key_usage(X509 *x)
 818 {
 819     /* Call for side-effect of computing hash and caching extensions */
 820     X509_check_purpose(x, -1, -1);
 821     if (x->ex_flags & EXFLAG_KUSAGE)
 822         return x->ex_kusage;
 823     return UINT32_MAX;
 824 }
 825
 826 uint32_t X509_get_extended_key_usage(X509 *x)
 827 {
 828     /* Call for side-effect of computing hash and caching extensions */
 829     X509_check_purpose(x, -1, -1);
 830     if (x->ex_flags & EXFLAG_XKUSAGE)
 831         return x->ex_xkusage;
 832     return UINT32_MAX;
 833 }
 834
 835 const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x)
 836 {
 837     /* Call for side-effect of computing hash and caching extensions */
 838     X509_check_purpose(x, -1, -1);
 839     return x->skid;
 840 }
 841
 842 long X509_get_pathlen(X509 *x)
 843 {
 844     /* Called for side effect of caching extensions */
 845     if (X509_check_purpose(x, -1, -1) != 1
 846             || (x->ex_flags & EXFLAG_BCONS) == 0)
 847         return -1;
 848     return x->ex_pathlen;
 849 }