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         return 0;
 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             return 0;
 201         }
 202         if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
 203             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 204             return 0;
 205         }
 206     }
 207     return 1;
 208 }
 209
 210 static void xptable_free(X509_PURPOSE *p)
 211 {
 212     if (!p)
 213         return;
 214     if (p->flags & X509_PURPOSE_DYNAMIC) {
 215         if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
 216             OPENSSL_free(p->name);
 217             OPENSSL_free(p->sname);
 218         }
 219         OPENSSL_free(p);
 220     }
 221 }
 222
 223 void X509_PURPOSE_cleanup(void)
 224 {
 225     unsigned int i;
 226     sk_X509_PURPOSE_pop_free(xptable, xptable_free);
 227     for (i = 0; i < X509_PURPOSE_COUNT; i++)
 228         xptable_free(xstandard + i);
 229     xptable = NULL;
 230 }
 231
 232 int X509_PURPOSE_get_id(X509_PURPOSE *xp)
 233 {
 234     return xp->purpose;
 235 }
 236
 237 char *X509_PURPOSE_get0_name(X509_PURPOSE *xp)
 238 {
 239     return xp->name;
 240 }
 241
 242 char *X509_PURPOSE_get0_sname(X509_PURPOSE *xp)
 243 {
 244     return xp->sname;
 245 }
 246
 247 int X509_PURPOSE_get_trust(X509_PURPOSE *xp)
 248 {
 249     return xp->trust;
 250 }
 251
 252 static int nid_cmp(const int *a, const int *b)
 253 {
 254     return *a - *b;
 255 }
 256
 257 DECLARE_OBJ_BSEARCH_CMP_FN(int, int, nid);
 258 IMPLEMENT_OBJ_BSEARCH_CMP_FN(int, int, nid);
 259
 260 int X509_supported_extension(X509_EXTENSION *ex)
 261 {
 262     /*
 263      * This table is a list of the NIDs of supported extensions: that is
 264      * those which are used by the verify process. If an extension is
 265      * critical and doesn't appear in this list then the verify process will
 266      * normally reject the certificate. The list must be kept in numerical
 267      * order because it will be searched using bsearch.
 268      */
 269
 270     static const int supported_nids[] = {
 271         NID_netscape_cert_type, /* 71 */
 272         NID_key_usage,          /* 83 */
 273         NID_subject_alt_name,   /* 85 */
 274         NID_basic_constraints,  /* 87 */
 275         NID_certificate_policies, /* 89 */
 276         NID_ext_key_usage,      /* 126 */
 277 #ifndef OPENSSL_NO_RFC3779
 278         NID_sbgp_ipAddrBlock,   /* 290 */
 279         NID_sbgp_autonomousSysNum, /* 291 */
 280 #endif
 281         NID_policy_constraints, /* 401 */
 282         NID_proxyCertInfo,      /* 663 */
 283         NID_name_constraints,   /* 666 */
 284         NID_policy_mappings,    /* 747 */
 285         NID_inhibit_any_policy  /* 748 */
 286     };
 287
 288     int ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 289
 290     if (ex_nid == NID_undef)
 291         return 0;
 292
 293     if (OBJ_bsearch_nid(&ex_nid, supported_nids, OSSL_NELEM(supported_nids)))
 294         return 1;
 295     return 0;
 296 }
 297
 298 static void setup_dp(X509 *x, DIST_POINT *dp)
 299 {
 300     X509_NAME *iname = NULL;
 301     int i;
 302     if (dp->reasons) {
 303         if (dp->reasons->length > 0)
 304             dp->dp_reasons = dp->reasons->data[0];
 305         if (dp->reasons->length > 1)
 306             dp->dp_reasons |= (dp->reasons->data[1] << 8);
 307         dp->dp_reasons &= CRLDP_ALL_REASONS;
 308     } else
 309         dp->dp_reasons = CRLDP_ALL_REASONS;
 310     if (!dp->distpoint || (dp->distpoint->type != 1))
 311         return;
 312     for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
 313         GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
 314         if (gen->type == GEN_DIRNAME) {
 315             iname = gen->d.directoryName;
 316             break;
 317         }
 318     }
 319     if (!iname)
 320         iname = X509_get_issuer_name(x);
 321
 322     DIST_POINT_set_dpname(dp->distpoint, iname);
 323
 324 }
 325
 326 static void setup_crldp(X509 *x)
 327 {
 328     int i;
 329     x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL);
 330     for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++)
 331         setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
 332 }
 333
 334 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 335 #define ku_reject(x, usage) \
 336         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 337 #define xku_reject(x, usage) \
 338         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 339 #define ns_reject(x, usage) \
 340         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 341
 342 static void x509v3_cache_extensions(X509 *x)
 343 {
 344     BASIC_CONSTRAINTS *bs;
 345     PROXY_CERT_INFO_EXTENSION *pci;
 346     ASN1_BIT_STRING *usage;
 347     ASN1_BIT_STRING *ns;
 348     EXTENDED_KEY_USAGE *extusage;
 349     X509_EXTENSION *ex;
 350
 351     int i;
 352     if (x->ex_flags & EXFLAG_SET)
 353         return;
 354     X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 355     /* V1 should mean no extensions ... */
 356     if (!X509_get_version(x))
 357         x->ex_flags |= EXFLAG_V1;
 358     /* Handle basic constraints */
 359     if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 360         if (bs->ca)
 361             x->ex_flags |= EXFLAG_CA;
 362         if (bs->pathlen) {
 363             if ((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 364                 || !bs->ca) {
 365                 x->ex_flags |= EXFLAG_INVALID;
 366                 x->ex_pathlen = 0;
 367             } else
 368                 x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 369         } else
 370             x->ex_pathlen = -1;
 371         BASIC_CONSTRAINTS_free(bs);
 372         x->ex_flags |= EXFLAG_BCONS;
 373     }
 374     /* Handle proxy certificates */
 375     if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
 376         if (x->ex_flags & EXFLAG_CA
 377             || X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
 378             || X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
 379             x->ex_flags |= EXFLAG_INVALID;
 380         }
 381         if (pci->pcPathLengthConstraint) {
 382             x->ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 383         } else
 384             x->ex_pcpathlen = -1;
 385         PROXY_CERT_INFO_EXTENSION_free(pci);
 386         x->ex_flags |= EXFLAG_PROXY;
 387     }
 388     /* Handle key usage */
 389     if ((usage = X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 390         if (usage->length > 0) {
 391             x->ex_kusage = usage->data[0];
 392             if (usage->length > 1)
 393                 x->ex_kusage |= usage->data[1] << 8;
 394         } else
 395             x->ex_kusage = 0;
 396         x->ex_flags |= EXFLAG_KUSAGE;
 397         ASN1_BIT_STRING_free(usage);
 398     }
 399     x->ex_xkusage = 0;
 400     if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 401         x->ex_flags |= EXFLAG_XKUSAGE;
 402         for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 403             switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
 404             case NID_server_auth:
 405                 x->ex_xkusage |= XKU_SSL_SERVER;
 406                 break;
 407
 408             case NID_client_auth:
 409                 x->ex_xkusage |= XKU_SSL_CLIENT;
 410                 break;
 411
 412             case NID_email_protect:
 413                 x->ex_xkusage |= XKU_SMIME;
 414                 break;
 415
 416             case NID_code_sign:
 417                 x->ex_xkusage |= XKU_CODE_SIGN;
 418                 break;
 419
 420             case NID_ms_sgc:
 421             case NID_ns_sgc:
 422                 x->ex_xkusage |= XKU_SGC;
 423                 break;
 424
 425             case NID_OCSP_sign:
 426                 x->ex_xkusage |= XKU_OCSP_SIGN;
 427                 break;
 428
 429             case NID_time_stamp:
 430                 x->ex_xkusage |= XKU_TIMESTAMP;
 431                 break;
 432
 433             case NID_dvcs:
 434                 x->ex_xkusage |= XKU_DVCS;
 435                 break;
 436
 437             case NID_anyExtendedKeyUsage:
 438                 x->ex_xkusage |= XKU_ANYEKU;
 439                 break;
 440             }
 441         }
 442         sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 443     }
 444
 445     if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 446         if (ns->length > 0)
 447             x->ex_nscert = ns->data[0];
 448         else
 449             x->ex_nscert = 0;
 450         x->ex_flags |= EXFLAG_NSCERT;
 451         ASN1_BIT_STRING_free(ns);
 452     }
 453     x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 454     x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 455     /* Does subject name match issuer ? */
 456     if (!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x))) {
 457         x->ex_flags |= EXFLAG_SI;
 458         /* If SKID matches AKID also indicate self signed */
 459         if (X509_check_akid(x, x->akid) == X509_V_OK &&
 460             !ku_reject(x, KU_KEY_CERT_SIGN))
 461             x->ex_flags |= EXFLAG_SS;
 462     }
 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 #ifndef OPENSSL_NO_RFC3779
 470     x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
 471     x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
 472                                        NULL, NULL);
 473 #endif
 474     for (i = 0; i < X509_get_ext_count(x); i++) {
 475         ex = X509_get_ext(x, i);
 476         if (OBJ_obj2nid(X509_EXTENSION_get_object(ex))
 477             == NID_freshest_crl)
 478             x->ex_flags |= EXFLAG_FRESHEST;
 479         if (!X509_EXTENSION_get_critical(ex))
 480             continue;
 481         if (!X509_supported_extension(ex)) {
 482             x->ex_flags |= EXFLAG_CRITICAL;
 483             break;
 484         }
 485     }
 486     x->ex_flags |= EXFLAG_SET;
 487 }
 488
 489 /*-
 490  * CA checks common to all purposes
 491  * return codes:
 492  * 0 not a CA
 493  * 1 is a CA
 494  * 2 basicConstraints absent so "maybe" a CA
 495  * 3 basicConstraints absent but self signed V1.
 496  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 497  */
 498
 499 static int check_ca(const X509 *x)
 500 {
 501     /* keyUsage if present should allow cert signing */
 502     if (ku_reject(x, KU_KEY_CERT_SIGN))
 503         return 0;
 504     if (x->ex_flags & EXFLAG_BCONS) {
 505         if (x->ex_flags & EXFLAG_CA)
 506             return 1;
 507         /* If basicConstraints says not a CA then say so */
 508         else
 509             return 0;
 510     } else {
 511         /* we support V1 roots for...  uh, I don't really know why. */
 512         if ((x->ex_flags & V1_ROOT) == V1_ROOT)
 513             return 3;
 514         /*
 515          * If key usage present it must have certSign so tolerate it
 516          */
 517         else if (x->ex_flags & EXFLAG_KUSAGE)
 518             return 4;
 519         /* Older certificates could have Netscape-specific CA types */
 520         else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
 521             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_THREAD_write_lock(x->lock);
 531         x509v3_cache_extensions(x);
 532         CRYPTO_THREAD_unlock(x->lock);
 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)
 544         return 0;
 545     /* check nsCertType if present */
 546     if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
 547         return ca_ret;
 548     else
 549         return 0;
 550 }
 551
 552 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
 553                                     int ca)
 554 {
 555     if (xku_reject(x, XKU_SSL_CLIENT))
 556         return 0;
 557     if (ca)
 558         return check_ssl_ca(x);
 559     /* We need to do digital signatures or key agreement */
 560     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
 561         return 0;
 562     /* nsCertType if present should allow SSL client use */
 563     if (ns_reject(x, NS_SSL_CLIENT))
 564         return 0;
 565     return 1;
 566 }
 567
 568 /*
 569  * Key usage needed for TLS/SSL server: digital signature, encipherment or
 570  * key agreement. The ssl code can check this more thoroughly for individual
 571  * key types.
 572  */
 573 #define KU_TLS \
 574         KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT
 575
 576 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 577                                     int ca)
 578 {
 579     if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
 580         return 0;
 581     if (ca)
 582         return check_ssl_ca(x);
 583
 584     if (ns_reject(x, NS_SSL_SERVER))
 585         return 0;
 586     if (ku_reject(x, KU_TLS))
 587         return 0;
 588
 589     return 1;
 590
 591 }
 592
 593 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 594                                        int ca)
 595 {
 596     int ret;
 597     ret = check_purpose_ssl_server(xp, x, ca);
 598     if (!ret || ca)
 599         return ret;
 600     /* We need to encipher or Netscape complains */
 601     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 602         return 0;
 603     return ret;
 604 }
 605
 606 /* common S/MIME checks */
 607 static int purpose_smime(const X509 *x, int ca)
 608 {
 609     if (xku_reject(x, XKU_SMIME))
 610         return 0;
 611     if (ca) {
 612         int ca_ret;
 613         ca_ret = check_ca(x);
 614         if (!ca_ret)
 615             return 0;
 616         /* check nsCertType if present */
 617         if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
 618             return ca_ret;
 619         else
 620             return 0;
 621     }
 622     if (x->ex_flags & EXFLAG_NSCERT) {
 623         if (x->ex_nscert & NS_SMIME)
 624             return 1;
 625         /* Workaround for some buggy certificates */
 626         if (x->ex_nscert & NS_SSL_CLIENT)
 627             return 2;
 628         return 0;
 629     }
 630     return 1;
 631 }
 632
 633 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
 634                                     int ca)
 635 {
 636     int ret;
 637     ret = purpose_smime(x, ca);
 638     if (!ret || ca)
 639         return ret;
 640     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION))
 641         return 0;
 642     return ret;
 643 }
 644
 645 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
 646                                        int ca)
 647 {
 648     int ret;
 649     ret = purpose_smime(x, ca);
 650     if (!ret || ca)
 651         return ret;
 652     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 653         return 0;
 654     return ret;
 655 }
 656
 657 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
 658                                   int ca)
 659 {
 660     if (ca) {
 661         int ca_ret;
 662         if ((ca_ret = check_ca(x)) != 2)
 663             return ca_ret;
 664         else
 665             return 0;
 666     }
 667     if (ku_reject(x, KU_CRL_SIGN))
 668         return 0;
 669     return 1;
 670 }
 671
 672 /*
 673  * OCSP helper: this is *not* a full OCSP check. It just checks that each CA
 674  * is valid. Additional checks must be made on the chain.
 675  */
 676
 677 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 678 {
 679     /*
 680      * Must be a valid CA.  Should we really support the "I don't know" value
 681      * (2)?
 682      */
 683     if (ca)
 684         return check_ca(x);
 685     /* leaf certificate is checked in OCSP_verify() */
 686     return 1;
 687 }
 688
 689 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
 690                                         int ca)
 691 {
 692     int i_ext;
 693
 694     /* If ca is true we must return if this is a valid CA certificate. */
 695     if (ca)
 696         return check_ca(x);
 697
 698     /*
 699      * Check the optional key usage field:
 700      * if Key Usage is present, it must be one of digitalSignature
 701      * and/or nonRepudiation (other values are not consistent and shall
 702      * be rejected).
 703      */
 704     if ((x->ex_flags & EXFLAG_KUSAGE)
 705         && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
 706             !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
 707         return 0;
 708
 709     /* Only time stamp key usage is permitted and it's required. */
 710     if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
 711         return 0;
 712
 713     /* Extended Key Usage MUST be critical */
 714     i_ext = X509_get_ext_by_NID((X509 *)x, NID_ext_key_usage, -1);
 715     if (i_ext >= 0) {
 716         X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
 717         if (!X509_EXTENSION_get_critical(ext))
 718             return 0;
 719     }
 720
 721     return 1;
 722 }
 723
 724 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 725 {
 726     return 1;
 727 }
 728
 729 /*-
 730  * Various checks to see if one certificate issued the second.
 731  * This can be used to prune a set of possible issuer certificates
 732  * which have been looked up using some simple method such as by
 733  * subject name.
 734  * These are:
 735  * 1. Check issuer_name(subject) == subject_name(issuer)
 736  * 2. If akid(subject) exists check it matches issuer
 737  * 3. If key_usage(issuer) exists check it supports certificate signing
 738  * returns 0 for OK, positive for reason for mismatch, reasons match
 739  * codes for X509_verify_cert()
 740  */
 741
 742 int X509_check_issued(X509 *issuer, X509 *subject)
 743 {
 744     if (X509_NAME_cmp(X509_get_subject_name(issuer),
 745                       X509_get_issuer_name(subject)))
 746         return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 747     x509v3_cache_extensions(issuer);
 748     x509v3_cache_extensions(subject);
 749
 750     if (subject->akid) {
 751         int ret = X509_check_akid(issuer, subject->akid);
 752         if (ret != X509_V_OK)
 753             return ret;
 754     }
 755
 756     if (subject->ex_flags & EXFLAG_PROXY) {
 757         if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 758             return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 759     } else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
 760         return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 761     return X509_V_OK;
 762 }
 763
 764 int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
 765 {
 766
 767     if (!akid)
 768         return X509_V_OK;
 769
 770     /* Check key ids (if present) */
 771     if (akid->keyid && issuer->skid &&
 772         ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid))
 773         return X509_V_ERR_AKID_SKID_MISMATCH;
 774     /* Check serial number */
 775     if (akid->serial &&
 776         ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
 777         return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 778     /* Check issuer name */
 779     if (akid->issuer) {
 780         /*
 781          * Ugh, for some peculiar reason AKID includes SEQUENCE OF
 782          * GeneralName. So look for a DirName. There may be more than one but
 783          * we only take any notice of the first.
 784          */
 785         GENERAL_NAMES *gens;
 786         GENERAL_NAME *gen;
 787         X509_NAME *nm = NULL;
 788         int i;
 789         gens = akid->issuer;
 790         for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 791             gen = sk_GENERAL_NAME_value(gens, i);
 792             if (gen->type == GEN_DIRNAME) {
 793                 nm = gen->d.dirn;
 794                 break;
 795             }
 796         }
 797         if (nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 798             return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 799     }
 800     return X509_V_OK;
 801 }
 802
 803 uint32_t X509_get_extension_flags(X509 *x)
 804 {
 805     /* Call for side-effect of computing hash and caching extensions */
 806     X509_check_purpose(x, -1, -1);
 807     return x->ex_flags;
 808 }
 809
 810 uint32_t X509_get_key_usage(X509 *x)
 811 {
 812     /* Call for side-effect of computing hash and caching extensions */
 813     X509_check_purpose(x, -1, -1);
 814     if (x->ex_flags & EXFLAG_KUSAGE)
 815         return x->ex_kusage;
 816     return UINT32_MAX;
 817 }
 818
 819 uint32_t X509_get_extended_key_usage(X509 *x)
 820 {
 821     /* Call for side-effect of computing hash and caching extensions */
 822     X509_check_purpose(x, -1, -1);
 823     if (x->ex_flags & EXFLAG_XKUSAGE)
 824         return x->ex_xkusage;
 825     return UINT32_MAX;
 826 }
 827
 828 const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x)
 829 {
 830     /* Call for side-effect of computing hash and caching extensions */
 831     X509_check_purpose(x, -1, -1);
 832     return x->skid;
 833 }