crypto/x509v3/v3_purp.c

   1 /*
   2  * Copyright 1999-2020 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 "crypto/x509.h"
  16 #include "internal/tsan_assist.h"
  17
  18 static void x509v3_cache_extensions(X509 *x);
  19
  20 static int check_ssl_ca(const X509 *x);
  21 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
  22                                     int ca);
  23 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
  24                                     int ca);
  25 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
  26                                        int ca);
  27 static int purpose_smime(const X509 *x, int ca);
  28 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
  29                                     int ca);
  30 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
  31                                        int ca);
  32 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
  33                                   int ca);
  34 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
  35                                         int ca);
  36 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
  37 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
  38
  39 static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b);
  40 static void xptable_free(X509_PURPOSE *p);
  41
  42 static X509_PURPOSE xstandard[] = {
  43     {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0,
  44      check_purpose_ssl_client, "SSL client", "sslclient", NULL},
  45     {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
  46      check_purpose_ssl_server, "SSL server", "sslserver", NULL},
  47     {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
  48      check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
  49     {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign,
  50      "S/MIME signing", "smimesign", NULL},
  51     {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0,
  52      check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
  53     {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign,
  54      "CRL signing", "crlsign", NULL},
  55     {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any",
  56      NULL},
  57     {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper,
  58      "OCSP helper", "ocsphelper", NULL},
  59     {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0,
  60      check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign",
  61      NULL},
  62 };
  63
  64 #define X509_PURPOSE_COUNT OSSL_NELEM(xstandard)
  65
  66 static STACK_OF(X509_PURPOSE) *xptable = NULL;
  67
  68 static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b)
  69 {
  70     return (*a)->purpose - (*b)->purpose;
  71 }
  72
  73 /*
  74  * As much as I'd like to make X509_check_purpose use a "const" X509* I
  75  * really can't because it does recalculate hashes and do other non-const
  76  * things.
  77  */
  78 int X509_check_purpose(X509 *x, int id, int ca)
  79 {
  80     int idx;
  81     const X509_PURPOSE *pt;
  82
  83     x509v3_cache_extensions(x);
  84     if (x->ex_flags & EXFLAG_INVALID)
  85         return -1;
  86
  87     /* Return if side-effect only call */
  88     if (id == -1)
  89         return 1;
  90     idx = X509_PURPOSE_get_by_id(id);
  91     if (idx == -1)
  92         return -1;
  93     pt = X509_PURPOSE_get0(idx);
  94     return pt->check_purpose(pt, x, ca);
  95 }
  96
  97 int X509_PURPOSE_set(int *p, int purpose)
  98 {
  99     if (X509_PURPOSE_get_by_id(purpose) == -1) {
 100         X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
 101         return 0;
 102     }
 103     *p = purpose;
 104     return 1;
 105 }
 106
 107 int X509_PURPOSE_get_count(void)
 108 {
 109     if (!xptable)
 110         return X509_PURPOSE_COUNT;
 111     return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
 112 }
 113
 114 X509_PURPOSE *X509_PURPOSE_get0(int idx)
 115 {
 116     if (idx < 0)
 117         return NULL;
 118     if (idx < (int)X509_PURPOSE_COUNT)
 119         return xstandard + idx;
 120     return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
 121 }
 122
 123 int X509_PURPOSE_get_by_sname(const char *sname)
 124 {
 125     int i;
 126     X509_PURPOSE *xptmp;
 127     for (i = 0; i < X509_PURPOSE_get_count(); i++) {
 128         xptmp = X509_PURPOSE_get0(i);
 129         if (strcmp(xptmp->sname, sname) == 0)
 130             return i;
 131     }
 132     return -1;
 133 }
 134
 135 int X509_PURPOSE_get_by_id(int purpose)
 136 {
 137     X509_PURPOSE tmp;
 138     int idx;
 139
 140     if ((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
 141         return purpose - X509_PURPOSE_MIN;
 142     if (xptable == NULL)
 143         return -1;
 144     tmp.purpose = purpose;
 145     idx = sk_X509_PURPOSE_find(xptable, &tmp);
 146     if (idx < 0)
 147         return -1;
 148     return idx + X509_PURPOSE_COUNT;
 149 }
 150
 151 int X509_PURPOSE_add(int id, int trust, int flags,
 152                      int (*ck) (const X509_PURPOSE *, const X509 *, int),
 153                      const char *name, const char *sname, void *arg)
 154 {
 155     int idx;
 156     X509_PURPOSE *ptmp;
 157     /*
 158      * This is set according to what we change: application can't set it
 159      */
 160     flags &= ~X509_PURPOSE_DYNAMIC;
 161     /* This will always be set for application modified trust entries */
 162     flags |= X509_PURPOSE_DYNAMIC_NAME;
 163     /* Get existing entry if any */
 164     idx = X509_PURPOSE_get_by_id(id);
 165     /* Need a new entry */
 166     if (idx == -1) {
 167         if ((ptmp = OPENSSL_malloc(sizeof(*ptmp))) == NULL) {
 168             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 169             return 0;
 170         }
 171         ptmp->flags = X509_PURPOSE_DYNAMIC;
 172     } else
 173         ptmp = X509_PURPOSE_get0(idx);
 174
 175     /* OPENSSL_free existing name if dynamic */
 176     if (ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
 177         OPENSSL_free(ptmp->name);
 178         OPENSSL_free(ptmp->sname);
 179     }
 180     /* dup supplied name */
 181     ptmp->name = OPENSSL_strdup(name);
 182     ptmp->sname = OPENSSL_strdup(sname);
 183     if (!ptmp->name || !ptmp->sname) {
 184         X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 185         goto err;
 186     }
 187     /* Keep the dynamic flag of existing entry */
 188     ptmp->flags &= X509_PURPOSE_DYNAMIC;
 189     /* Set all other flags */
 190     ptmp->flags |= flags;
 191
 192     ptmp->purpose = id;
 193     ptmp->trust = trust;
 194     ptmp->check_purpose = ck;
 195     ptmp->usr_data = arg;
 196
 197     /* If its a new entry manage the dynamic table */
 198     if (idx == -1) {
 199         if (xptable == NULL
 200             && (xptable = sk_X509_PURPOSE_new(xp_cmp)) == NULL) {
 201             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 202             goto err;
 203         }
 204         if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
 205             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 206             goto err;
 207         }
 208     }
 209     return 1;
 210  err:
 211     if (idx == -1) {
 212         OPENSSL_free(ptmp->name);
 213         OPENSSL_free(ptmp->sname);
 214         OPENSSL_free(ptmp);
 215     }
 216     return 0;
 217 }
 218
 219 static void xptable_free(X509_PURPOSE *p)
 220 {
 221     if (!p)
 222         return;
 223     if (p->flags & X509_PURPOSE_DYNAMIC) {
 224         if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
 225             OPENSSL_free(p->name);
 226             OPENSSL_free(p->sname);
 227         }
 228         OPENSSL_free(p);
 229     }
 230 }
 231
 232 void X509_PURPOSE_cleanup(void)
 233 {
 234     sk_X509_PURPOSE_pop_free(xptable, xptable_free);
 235     xptable = NULL;
 236 }
 237
 238 int X509_PURPOSE_get_id(const X509_PURPOSE *xp)
 239 {
 240     return xp->purpose;
 241 }
 242
 243 char *X509_PURPOSE_get0_name(const X509_PURPOSE *xp)
 244 {
 245     return xp->name;
 246 }
 247
 248 char *X509_PURPOSE_get0_sname(const X509_PURPOSE *xp)
 249 {
 250     return xp->sname;
 251 }
 252
 253 int X509_PURPOSE_get_trust(const X509_PURPOSE *xp)
 254 {
 255     return xp->trust;
 256 }
 257
 258 static int nid_cmp(const int *a, const int *b)
 259 {
 260     return *a - *b;
 261 }
 262
 263 DECLARE_OBJ_BSEARCH_CMP_FN(int, int, nid);
 264 IMPLEMENT_OBJ_BSEARCH_CMP_FN(int, int, nid);
 265
 266 int X509_supported_extension(X509_EXTENSION *ex)
 267 {
 268     /*
 269      * This table is a list of the NIDs of supported extensions: that is
 270      * those which are used by the verify process. If an extension is
 271      * critical and doesn't appear in this list then the verify process will
 272      * normally reject the certificate. The list must be kept in numerical
 273      * order because it will be searched using bsearch.
 274      */
 275
 276     static const int supported_nids[] = {
 277         NID_netscape_cert_type, /* 71 */
 278         NID_key_usage,          /* 83 */
 279         NID_subject_alt_name,   /* 85 */
 280         NID_basic_constraints,  /* 87 */
 281         NID_certificate_policies, /* 89 */
 282         NID_crl_distribution_points, /* 103 */
 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 int setup_dp(X509 *x, DIST_POINT *dp)
 306 {
 307     X509_NAME *iname = NULL;
 308     int i;
 309
 310     if (dp->reasons) {
 311         if (dp->reasons->length > 0)
 312             dp->dp_reasons = dp->reasons->data[0];
 313         if (dp->reasons->length > 1)
 314             dp->dp_reasons |= (dp->reasons->data[1] << 8);
 315         dp->dp_reasons &= CRLDP_ALL_REASONS;
 316     } else
 317         dp->dp_reasons = CRLDP_ALL_REASONS;
 318     if (!dp->distpoint || (dp->distpoint->type != 1))
 319         return 1;
 320     for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
 321         GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
 322         if (gen->type == GEN_DIRNAME) {
 323             iname = gen->d.directoryName;
 324             break;
 325         }
 326     }
 327     if (!iname)
 328         iname = X509_get_issuer_name(x);
 329
 330     return DIST_POINT_set_dpname(dp->distpoint, iname);
 331 }
 332
 333 static int setup_crldp(X509 *x)
 334 {
 335     int i;
 336
 337     x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &i, NULL);
 338     if (x->crldp == NULL && i != -1)
 339         return 0;
 340     for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) {
 341         if (!setup_dp(x, sk_DIST_POINT_value(x->crldp, i)))
 342             return 0;
 343     }
 344     return 1;
 345 }
 346
 347 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 348 #define ku_reject(x, usage) \
 349         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 350 #define xku_reject(x, usage) \
 351         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 352 #define ns_reject(x, usage) \
 353         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 354
 355 static void x509v3_cache_extensions(X509 *x)
 356 {
 357     BASIC_CONSTRAINTS *bs;
 358     PROXY_CERT_INFO_EXTENSION *pci;
 359     ASN1_BIT_STRING *usage;
 360     ASN1_BIT_STRING *ns;
 361     EXTENDED_KEY_USAGE *extusage;
 362     X509_EXTENSION *ex;
 363     int i;
 364
 365 #ifdef tsan_ld_acq
 366     /* fast lock-free check, see end of the function for details. */
 367     if (tsan_ld_acq((TSAN_QUALIFIER int *)&x->ex_cached))
 368         return;
 369 #endif
 370
 371     CRYPTO_THREAD_write_lock(x->lock);
 372     if (x->ex_flags & EXFLAG_SET) {
 373         CRYPTO_THREAD_unlock(x->lock);
 374         return;
 375     }
 376
 377     if (!X509_digest(x, EVP_sha1(), x->sha1_hash, NULL))
 378         x->ex_flags |= EXFLAG_INVALID;
 379     /* V1 should mean no extensions ... */
 380     if (!X509_get_version(x))
 381         x->ex_flags |= EXFLAG_V1;
 382     /* Handle basic constraints */
 383     if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, &i, NULL))) {
 384         if (bs->ca)
 385             x->ex_flags |= EXFLAG_CA;
 386         if (bs->pathlen) {
 387             if ((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 388                 || !bs->ca) {
 389                 x->ex_flags |= EXFLAG_INVALID;
 390                 x->ex_pathlen = 0;
 391             } else
 392                 x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 393         } else
 394             x->ex_pathlen = -1;
 395         BASIC_CONSTRAINTS_free(bs);
 396         x->ex_flags |= EXFLAG_BCONS;
 397     } else if (i != -1) {
 398         x->ex_flags |= EXFLAG_INVALID;
 399     }
 400     /* Handle proxy certificates */
 401     if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, &i, NULL))) {
 402         if (x->ex_flags & EXFLAG_CA
 403             || X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
 404             || X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
 405             x->ex_flags |= EXFLAG_INVALID;
 406         }
 407         if (pci->pcPathLengthConstraint) {
 408             x->ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 409         } else
 410             x->ex_pcpathlen = -1;
 411         PROXY_CERT_INFO_EXTENSION_free(pci);
 412         x->ex_flags |= EXFLAG_PROXY;
 413     } else if (i != -1) {
 414         x->ex_flags |= EXFLAG_INVALID;
 415     }
 416     /* Handle key usage */
 417     if ((usage = X509_get_ext_d2i(x, NID_key_usage, &i, NULL))) {
 418         if (usage->length > 0) {
 419             x->ex_kusage = usage->data[0];
 420             if (usage->length > 1)
 421                 x->ex_kusage |= usage->data[1] << 8;
 422         } else
 423             x->ex_kusage = 0;
 424         x->ex_flags |= EXFLAG_KUSAGE;
 425         ASN1_BIT_STRING_free(usage);
 426     } else if (i != -1) {
 427         x->ex_flags |= EXFLAG_INVALID;
 428     }
 429     x->ex_xkusage = 0;
 430     if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, &i, NULL))) {
 431         x->ex_flags |= EXFLAG_XKUSAGE;
 432         for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 433             switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
 434             case NID_server_auth:
 435                 x->ex_xkusage |= XKU_SSL_SERVER;
 436                 break;
 437
 438             case NID_client_auth:
 439                 x->ex_xkusage |= XKU_SSL_CLIENT;
 440                 break;
 441
 442             case NID_email_protect:
 443                 x->ex_xkusage |= XKU_SMIME;
 444                 break;
 445
 446             case NID_code_sign:
 447                 x->ex_xkusage |= XKU_CODE_SIGN;
 448                 break;
 449
 450             case NID_ms_sgc:
 451             case NID_ns_sgc:
 452                 x->ex_xkusage |= XKU_SGC;
 453                 break;
 454
 455             case NID_OCSP_sign:
 456                 x->ex_xkusage |= XKU_OCSP_SIGN;
 457                 break;
 458
 459             case NID_time_stamp:
 460                 x->ex_xkusage |= XKU_TIMESTAMP;
 461                 break;
 462
 463             case NID_dvcs:
 464                 x->ex_xkusage |= XKU_DVCS;
 465                 break;
 466
 467             case NID_anyExtendedKeyUsage:
 468                 x->ex_xkusage |= XKU_ANYEKU;
 469                 break;
 470             }
 471         }
 472         sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 473     } else if (i != -1) {
 474         x->ex_flags |= EXFLAG_INVALID;
 475     }
 476
 477     if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, &i, NULL))) {
 478         if (ns->length > 0)
 479             x->ex_nscert = ns->data[0];
 480         else
 481             x->ex_nscert = 0;
 482         x->ex_flags |= EXFLAG_NSCERT;
 483         ASN1_BIT_STRING_free(ns);
 484     } else if (i != -1) {
 485         x->ex_flags |= EXFLAG_INVALID;
 486     }
 487     x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, &i, NULL);
 488     if (x->skid == NULL && i != -1)
 489         x->ex_flags |= EXFLAG_INVALID;
 490     x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, &i, NULL);
 491     if (x->akid == NULL && i != -1)
 492         x->ex_flags |= EXFLAG_INVALID;
 493     /* Does subject name match issuer ? */
 494     if (!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x))) {
 495         x->ex_flags |= EXFLAG_SI;
 496         /* If SKID matches AKID also indicate self signed */
 497         if (X509_check_akid(x, x->akid) == X509_V_OK &&
 498             !ku_reject(x, KU_KEY_CERT_SIGN))
 499             x->ex_flags |= EXFLAG_SS;
 500     }
 501     x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, &i, NULL);
 502     if (x->altname == NULL && i != -1)
 503         x->ex_flags |= EXFLAG_INVALID;
 504     x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
 505     if (x->nc == NULL && i != -1)
 506         x->ex_flags |= EXFLAG_INVALID;
 507     if (!setup_crldp(x))
 508         x->ex_flags |= EXFLAG_INVALID;
 509
 510 #ifndef OPENSSL_NO_RFC3779
 511     x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, &i, NULL);
 512     if (x->rfc3779_addr == NULL && i != -1)
 513         x->ex_flags |= EXFLAG_INVALID;
 514     x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum, &i, NULL);
 515     if (x->rfc3779_asid == NULL && i != -1)
 516         x->ex_flags |= EXFLAG_INVALID;
 517 #endif
 518     for (i = 0; i < X509_get_ext_count(x); i++) {
 519         ex = X509_get_ext(x, i);
 520         if (OBJ_obj2nid(X509_EXTENSION_get_object(ex))
 521             == NID_freshest_crl)
 522             x->ex_flags |= EXFLAG_FRESHEST;
 523         if (!X509_EXTENSION_get_critical(ex))
 524             continue;
 525         if (!X509_supported_extension(ex)) {
 526             x->ex_flags |= EXFLAG_CRITICAL;
 527             break;
 528         }
 529     }
 530     x509_init_sig_info(x);
 531     x->ex_flags |= EXFLAG_SET;
 532 #ifdef tsan_st_rel
 533     tsan_st_rel((TSAN_QUALIFIER int *)&x->ex_cached, 1);
 534     /*
 535      * Above store triggers fast lock-free check in the beginning of the
 536      * function. But one has to ensure that the structure is "stable", i.e.
 537      * all stores are visible on all processors. Hence the release fence.
 538      */
 539 #endif
 540     CRYPTO_THREAD_unlock(x->lock);
 541 }
 542
 543 /*-
 544  * CA checks common to all purposes
 545  * return codes:
 546  * 0 not a CA
 547  * 1 is a CA
 548  * 2 basicConstraints absent so "maybe" a CA
 549  * 3 basicConstraints absent but self signed V1.
 550  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 551  */
 552
 553 static int check_ca(const X509 *x)
 554 {
 555     /* keyUsage if present should allow cert signing */
 556     if (ku_reject(x, KU_KEY_CERT_SIGN))
 557         return 0;
 558     if (x->ex_flags & EXFLAG_BCONS) {
 559         if (x->ex_flags & EXFLAG_CA)
 560             return 1;
 561         /* If basicConstraints says not a CA then say so */
 562         else
 563             return 0;
 564     } else {
 565         /* we support V1 roots for...  uh, I don't really know why. */
 566         if ((x->ex_flags & V1_ROOT) == V1_ROOT)
 567             return 3;
 568         /*
 569          * If key usage present it must have certSign so tolerate it
 570          */
 571         else if (x->ex_flags & EXFLAG_KUSAGE)
 572             return 4;
 573         /* Older certificates could have Netscape-specific CA types */
 574         else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
 575             return 5;
 576         /* can this still be regarded a CA certificate?  I doubt it */
 577         return 0;
 578     }
 579 }
 580
 581 void X509_set_proxy_flag(X509 *x)
 582 {
 583     x->ex_flags |= EXFLAG_PROXY;
 584 }
 585
 586 void X509_set_proxy_pathlen(X509 *x, long l)
 587 {
 588     x->ex_pcpathlen = l;
 589 }
 590
 591 int X509_check_ca(X509 *x)
 592 {
 593     x509v3_cache_extensions(x);
 594
 595     return check_ca(x);
 596 }
 597
 598 /* Check SSL CA: common checks for SSL client and server */
 599 static int check_ssl_ca(const X509 *x)
 600 {
 601     int ca_ret;
 602     ca_ret = check_ca(x);
 603     if (!ca_ret)
 604         return 0;
 605     /* check nsCertType if present */
 606     if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
 607         return ca_ret;
 608     else
 609         return 0;
 610 }
 611
 612 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
 613                                     int ca)
 614 {
 615     if (xku_reject(x, XKU_SSL_CLIENT))
 616         return 0;
 617     if (ca)
 618         return check_ssl_ca(x);
 619     /* We need to do digital signatures or key agreement */
 620     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
 621         return 0;
 622     /* nsCertType if present should allow SSL client use */
 623     if (ns_reject(x, NS_SSL_CLIENT))
 624         return 0;
 625     return 1;
 626 }
 627
 628 /*
 629  * Key usage needed for TLS/SSL server: digital signature, encipherment or
 630  * key agreement. The ssl code can check this more thoroughly for individual
 631  * key types.
 632  */
 633 #define KU_TLS \
 634         KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT
 635
 636 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 637                                     int ca)
 638 {
 639     if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
 640         return 0;
 641     if (ca)
 642         return check_ssl_ca(x);
 643
 644     if (ns_reject(x, NS_SSL_SERVER))
 645         return 0;
 646     if (ku_reject(x, KU_TLS))
 647         return 0;
 648
 649     return 1;
 650
 651 }
 652
 653 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 654                                        int ca)
 655 {
 656     int ret;
 657     ret = check_purpose_ssl_server(xp, x, ca);
 658     if (!ret || ca)
 659         return ret;
 660     /* We need to encipher or Netscape complains */
 661     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 662         return 0;
 663     return ret;
 664 }
 665
 666 /* common S/MIME checks */
 667 static int purpose_smime(const X509 *x, int ca)
 668 {
 669     if (xku_reject(x, XKU_SMIME))
 670         return 0;
 671     if (ca) {
 672         int ca_ret;
 673         ca_ret = check_ca(x);
 674         if (!ca_ret)
 675             return 0;
 676         /* check nsCertType if present */
 677         if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
 678             return ca_ret;
 679         else
 680             return 0;
 681     }
 682     if (x->ex_flags & EXFLAG_NSCERT) {
 683         if (x->ex_nscert & NS_SMIME)
 684             return 1;
 685         /* Workaround for some buggy certificates */
 686         if (x->ex_nscert & NS_SSL_CLIENT)
 687             return 2;
 688         return 0;
 689     }
 690     return 1;
 691 }
 692
 693 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
 694                                     int ca)
 695 {
 696     int ret;
 697     ret = purpose_smime(x, ca);
 698     if (!ret || ca)
 699         return ret;
 700     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION))
 701         return 0;
 702     return ret;
 703 }
 704
 705 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
 706                                        int ca)
 707 {
 708     int ret;
 709     ret = purpose_smime(x, ca);
 710     if (!ret || ca)
 711         return ret;
 712     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 713         return 0;
 714     return ret;
 715 }
 716
 717 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
 718                                   int ca)
 719 {
 720     if (ca) {
 721         int ca_ret;
 722         if ((ca_ret = check_ca(x)) != 2)
 723             return ca_ret;
 724         else
 725             return 0;
 726     }
 727     if (ku_reject(x, KU_CRL_SIGN))
 728         return 0;
 729     return 1;
 730 }
 731
 732 /*
 733  * OCSP helper: this is *not* a full OCSP check. It just checks that each CA
 734  * is valid. Additional checks must be made on the chain.
 735  */
 736
 737 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 738 {
 739     /*
 740      * Must be a valid CA.  Should we really support the "I don't know" value
 741      * (2)?
 742      */
 743     if (ca)
 744         return check_ca(x);
 745     /* leaf certificate is checked in OCSP_verify() */
 746     return 1;
 747 }
 748
 749 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
 750                                         int ca)
 751 {
 752     int i_ext;
 753
 754     /* If ca is true we must return if this is a valid CA certificate. */
 755     if (ca)
 756         return check_ca(x);
 757
 758     /*
 759      * Check the optional key usage field:
 760      * if Key Usage is present, it must be one of digitalSignature
 761      * and/or nonRepudiation (other values are not consistent and shall
 762      * be rejected).
 763      */
 764     if ((x->ex_flags & EXFLAG_KUSAGE)
 765         && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
 766             !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
 767         return 0;
 768
 769     /* Only time stamp key usage is permitted and it's required. */
 770     if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
 771         return 0;
 772
 773     /* Extended Key Usage MUST be critical */
 774     i_ext = X509_get_ext_by_NID(x, NID_ext_key_usage, -1);
 775     if (i_ext >= 0) {
 776         X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
 777         if (!X509_EXTENSION_get_critical(ext))
 778             return 0;
 779     }
 780
 781     return 1;
 782 }
 783
 784 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 785 {
 786     return 1;
 787 }
 788
 789 /*-
 790  * Various checks to see if one certificate issued the second.
 791  * This can be used to prune a set of possible issuer certificates
 792  * which have been looked up using some simple method such as by
 793  * subject name.
 794  * These are:
 795  * 1. Check issuer_name(subject) == subject_name(issuer)
 796  * 2. If akid(subject) exists check it matches issuer
 797  * 3. If key_usage(issuer) exists check it supports certificate signing
 798  * returns 0 for OK, positive for reason for mismatch, reasons match
 799  * codes for X509_verify_cert()
 800  */
 801
 802 int X509_check_issued(X509 *issuer, X509 *subject)
 803 {
 804     if (X509_NAME_cmp(X509_get_subject_name(issuer),
 805                       X509_get_issuer_name(subject)))
 806         return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 807
 808     x509v3_cache_extensions(issuer);
 809     if (issuer->ex_flags & EXFLAG_INVALID)
 810         return X509_V_ERR_UNSPECIFIED;
 811     x509v3_cache_extensions(subject);
 812     if (subject->ex_flags & EXFLAG_INVALID)
 813         return X509_V_ERR_UNSPECIFIED;
 814
 815     if (subject->akid) {
 816         int ret = X509_check_akid(issuer, subject->akid);
 817         if (ret != X509_V_OK)
 818             return ret;
 819     }
 820
 821     if (subject->ex_flags & EXFLAG_PROXY) {
 822         if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 823             return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 824     } else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
 825         return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 826     return X509_V_OK;
 827 }
 828
 829 int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
 830 {
 831
 832     if (!akid)
 833         return X509_V_OK;
 834
 835     /* Check key ids (if present) */
 836     if (akid->keyid && issuer->skid &&
 837         ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid))
 838         return X509_V_ERR_AKID_SKID_MISMATCH;
 839     /* Check serial number */
 840     if (akid->serial &&
 841         ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
 842         return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 843     /* Check issuer name */
 844     if (akid->issuer) {
 845         /*
 846          * Ugh, for some peculiar reason AKID includes SEQUENCE OF
 847          * GeneralName. So look for a DirName. There may be more than one but
 848          * we only take any notice of the first.
 849          */
 850         GENERAL_NAMES *gens;
 851         GENERAL_NAME *gen;
 852         X509_NAME *nm = NULL;
 853         int i;
 854         gens = akid->issuer;
 855         for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 856             gen = sk_GENERAL_NAME_value(gens, i);
 857             if (gen->type == GEN_DIRNAME) {
 858                 nm = gen->d.dirn;
 859                 break;
 860             }
 861         }
 862         if (nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 863             return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 864     }
 865     return X509_V_OK;
 866 }
 867
 868 uint32_t X509_get_extension_flags(X509 *x)
 869 {
 870     /* Call for side-effect of computing hash and caching extensions */
 871     X509_check_purpose(x, -1, -1);
 872     return x->ex_flags;
 873 }
 874
 875 uint32_t X509_get_key_usage(X509 *x)
 876 {
 877     /* Call for side-effect of computing hash and caching extensions */
 878     if (X509_check_purpose(x, -1, -1) != 1)
 879         return 0;
 880     if (x->ex_flags & EXFLAG_KUSAGE)
 881         return x->ex_kusage;
 882     return UINT32_MAX;
 883 }
 884
 885 uint32_t X509_get_extended_key_usage(X509 *x)
 886 {
 887     /* Call for side-effect of computing hash and caching extensions */
 888     if (X509_check_purpose(x, -1, -1) != 1)
 889         return 0;
 890     if (x->ex_flags & EXFLAG_XKUSAGE)
 891         return x->ex_xkusage;
 892     return UINT32_MAX;
 893 }
 894
 895 const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x)
 896 {
 897     /* Call for side-effect of computing hash and caching extensions */
 898     if (X509_check_purpose(x, -1, -1) != 1)
 899         return NULL;
 900     return x->skid;
 901 }
 902
 903 const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x)
 904 {
 905     /* Call for side-effect of computing hash and caching extensions */
 906     if (X509_check_purpose(x, -1, -1) != 1)
 907         return NULL;
 908     return (x->akid != NULL ? x->akid->keyid : NULL);
 909 }
 910
 911 const GENERAL_NAMES *X509_get0_authority_issuer(X509 *x)
 912 {
 913     /* Call for side-effect of computing hash and caching extensions */
 914     if (X509_check_purpose(x, -1, -1) != 1)
 915         return NULL;
 916     return (x->akid != NULL ? x->akid->issuer : NULL);
 917 }
 918
 919 const ASN1_INTEGER *X509_get0_authority_serial(X509 *x)
 920 {
 921     /* Call for side-effect of computing hash and caching extensions */
 922     if (X509_check_purpose(x, -1, -1) != 1)
 923         return NULL;
 924     return (x->akid != NULL ? x->akid->serial : NULL);
 925 }
 926
 927 long X509_get_pathlen(X509 *x)
 928 {
 929     /* Called for side effect of caching extensions */
 930     if (X509_check_purpose(x, -1, -1) != 1
 931             || (x->ex_flags & EXFLAG_BCONS) == 0)
 932         return -1;
 933     return x->ex_pathlen;
 934 }
 935
 936 long X509_get_proxy_pathlen(X509 *x)
 937 {
 938     /* Called for side effect of caching extensions */
 939     if (X509_check_purpose(x, -1, -1) != 1
 940             || (x->ex_flags & EXFLAG_PROXY) == 0)
 941         return -1;
 942     return x->ex_pcpathlen;
 943 }