crypto/x509/v3_purp.c

   1 /*
   2  * Copyright 1999-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (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 #include "x509_local.h"
  18
  19 DEFINE_STACK_OF(ASN1_OBJECT)
  20
  21 static int check_ssl_ca(const X509 *x);
  22 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
  23                                     int ca);
  24 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
  25                                     int ca);
  26 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
  27                                        int ca);
  28 static int purpose_smime(const X509 *x, int ca);
  29 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
  30                                     int ca);
  31 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
  32                                        int ca);
  33 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
  34                                   int ca);
  35 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
  36                                         int ca);
  37 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
  38 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
  39
  40 static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b);
  41 static void xptable_free(X509_PURPOSE *p);
  42
  43 static X509_PURPOSE xstandard[] = {
  44     {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0,
  45      check_purpose_ssl_client, "SSL client", "sslclient", NULL},
  46     {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
  47      check_purpose_ssl_server, "SSL server", "sslserver", NULL},
  48     {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
  49      check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
  50     {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign,
  51      "S/MIME signing", "smimesign", NULL},
  52     {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0,
  53      check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
  54     {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign,
  55      "CRL signing", "crlsign", NULL},
  56     {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any",
  57      NULL},
  58     {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper,
  59      "OCSP helper", "ocsphelper", NULL},
  60     {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0,
  61      check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign",
  62      NULL},
  63 };
  64
  65 #define X509_PURPOSE_COUNT OSSL_NELEM(xstandard)
  66
  67 static STACK_OF(X509_PURPOSE) *xptable = NULL;
  68
  69 static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b)
  70 {
  71     return (*a)->purpose - (*b)->purpose;
  72 }
  73
  74 /*
  75  * As much as I'd like to make X509_check_purpose use a "const" X509* I
  76  * really can't because it does recalculate hashes and do other non-const
  77  * things.
  78  */
  79 int X509_check_purpose(X509 *x, int id, int ca)
  80 {
  81     int idx;
  82     const X509_PURPOSE *pt;
  83
  84     if (!x509v3_cache_extensions(x))
  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 == NULL|| ptmp->sname == NULL) {
 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 == NULL)
 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 /* return 1 on success, 0 if x is invalid, -1 on (internal) error */
 306 static int setup_dp(const X509 *x, DIST_POINT *dp)
 307 {
 308     const X509_NAME *iname = NULL;
 309     int i;
 310
 311     if (dp->distpoint == NULL && sk_GENERAL_NAME_num(dp->CRLissuer) <= 0) {
 312         X509err(0, X509_R_INVALID_DISTPOINT);
 313         return 0;
 314     }
 315     if (dp->reasons != NULL) {
 316         if (dp->reasons->length > 0)
 317             dp->dp_reasons = dp->reasons->data[0];
 318         if (dp->reasons->length > 1)
 319             dp->dp_reasons |= (dp->reasons->data[1] << 8);
 320         dp->dp_reasons &= CRLDP_ALL_REASONS;
 321     } else {
 322         dp->dp_reasons = CRLDP_ALL_REASONS;
 323     }
 324     if (dp->distpoint == NULL || dp->distpoint->type != 1)
 325         return 1;
 326
 327     /* handle name fragment given by nameRelativeToCRLIssuer */
 328     /*
 329      * Note that the below way of determining iname is not really compliant
 330      * with https://tools.ietf.org/html/rfc5280#section-4.2.1.13
 331      * According to it, sk_GENERAL_NAME_num(dp->CRLissuer) MUST be <= 1
 332      * and any CRLissuer could be of type different to GEN_DIRNAME.
 333      */
 334     for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
 335         GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
 336
 337         if (gen->type == GEN_DIRNAME) {
 338             iname = gen->d.directoryName;
 339             break;
 340         }
 341     }
 342     if (iname == NULL)
 343         iname = X509_get_issuer_name(x);
 344     return DIST_POINT_set_dpname(dp->distpoint, iname) ? 1 : -1;
 345 }
 346
 347 /* return 1 on success, 0 if x is invalid, -1 on (internal) error */
 348 static int setup_crldp(X509 *x)
 349 {
 350     int i;
 351
 352     x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &i, NULL);
 353     if (x->crldp == NULL && i != -1)
 354         return 0;
 355
 356     for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) {
 357         int res = setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
 358
 359         if (res < 1)
 360             return res;
 361     }
 362     return 1;
 363 }
 364
 365 /* Check that issuer public key algorithm matches subject signature algorithm */
 366 static int check_sig_alg_match(const EVP_PKEY *pkey, const X509 *subject)
 367 {
 368     int pkey_nid;
 369
 370     if (pkey == NULL)
 371         return X509_V_ERR_NO_ISSUER_PUBLIC_KEY;
 372     if (OBJ_find_sigid_algs(OBJ_obj2nid(subject->cert_info.signature.algorithm),
 373                             NULL, &pkey_nid) == 0)
 374         return X509_V_ERR_UNSUPPORTED_SIGNATURE_ALGORITHM;
 375     if (EVP_PKEY_type(pkey_nid) != EVP_PKEY_base_id(pkey))
 376         return X509_V_ERR_SIGNATURE_ALGORITHM_MISMATCH;
 377     return X509_V_OK;
 378 }
 379
 380 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 381 #define ku_reject(x, usage) \
 382         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 383 #define xku_reject(x, usage) \
 384         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 385 #define ns_reject(x, usage) \
 386         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 387
 388 /*
 389  * Cache info on various X.509v3 extensions and further derived information,
 390  * e.g., if cert 'x' is self-issued, in x->ex_flags and other internal fields.
 391  * X509_SIG_INFO_VALID is set in x->flags if x->siginf was filled successfully.
 392  * Set EXFLAG_INVALID and return 0 in case the certificate is invalid.
 393  */
 394 int x509v3_cache_extensions(X509 *x)
 395 {
 396     BASIC_CONSTRAINTS *bs;
 397     PROXY_CERT_INFO_EXTENSION *pci;
 398     ASN1_BIT_STRING *usage;
 399     ASN1_BIT_STRING *ns;
 400     EXTENDED_KEY_USAGE *extusage;
 401     int i;
 402     int res;
 403
 404 #ifdef tsan_ld_acq
 405     /* fast lock-free check, see end of the function for details. */
 406     if (tsan_ld_acq((TSAN_QUALIFIER int *)&x->ex_cached))
 407         return (x->ex_flags & EXFLAG_INVALID) == 0;
 408 #endif
 409
 410     CRYPTO_THREAD_write_lock(x->lock);
 411     if (x->ex_flags & EXFLAG_SET) { /* cert has already been processed */
 412         CRYPTO_THREAD_unlock(x->lock);
 413         return (x->ex_flags & EXFLAG_INVALID) == 0;
 414     }
 415     ERR_set_mark();
 416
 417     /* Cache the SHA1 digest of the cert */
 418     if (!X509_digest(x, EVP_sha1(), x->sha1_hash, NULL))
 419         /*
 420          * Note that the cert is marked invalid also on internal malloc failure
 421          * or on failure of EVP_MD_fetch(), potentially called by X509_digest().
 422          */
 423         x->ex_flags |= EXFLAG_INVALID;
 424
 425     /* V1 should mean no extensions ... */
 426     if (X509_get_version(x) == 0)
 427         x->ex_flags |= EXFLAG_V1;
 428
 429     /* Handle basic constraints */
 430     x->ex_pathlen = -1;
 431     if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, &i, NULL)) != NULL) {
 432         if (bs->ca)
 433             x->ex_flags |= EXFLAG_CA;
 434         if (bs->pathlen != NULL) {
 435             /*
 436              * the error case !bs->ca is checked by check_chain_extensions()
 437              * in case ctx->param->flags & X509_V_FLAG_X509_STRICT
 438              */
 439             if (bs->pathlen->type == V_ASN1_NEG_INTEGER) {
 440                 X509err(0, X509V3_R_NEGATIVE_PATHLEN);
 441                 x->ex_flags |= EXFLAG_INVALID;
 442             } else {
 443                 x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 444             }
 445         }
 446         BASIC_CONSTRAINTS_free(bs);
 447         x->ex_flags |= EXFLAG_BCONS;
 448     } else if (i != -1) {
 449         x->ex_flags |= EXFLAG_INVALID;
 450     }
 451
 452     /* Handle proxy certificates */
 453     if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, &i, NULL)) != NULL) {
 454         if (x->ex_flags & EXFLAG_CA
 455             || X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
 456             || X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
 457             x->ex_flags |= EXFLAG_INVALID;
 458         }
 459         if (pci->pcPathLengthConstraint != NULL)
 460             x->ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 461         else
 462             x->ex_pcpathlen = -1;
 463         PROXY_CERT_INFO_EXTENSION_free(pci);
 464         x->ex_flags |= EXFLAG_PROXY;
 465     } else if (i != -1) {
 466         x->ex_flags |= EXFLAG_INVALID;
 467     }
 468
 469     /* Handle (basic) key usage */
 470     if ((usage = X509_get_ext_d2i(x, NID_key_usage, &i, NULL)) != NULL) {
 471         x->ex_kusage = 0;
 472         if (usage->length > 0) {
 473             x->ex_kusage = usage->data[0];
 474             if (usage->length > 1)
 475                 x->ex_kusage |= usage->data[1] << 8;
 476         }
 477         x->ex_flags |= EXFLAG_KUSAGE;
 478         ASN1_BIT_STRING_free(usage);
 479         /* Check for empty key usage according to RFC 5280 section 4.2.1.3 */
 480         if (x->ex_kusage == 0) {
 481             X509err(0, X509V3_R_EMPTY_KEY_USAGE);
 482             x->ex_flags |= EXFLAG_INVALID;
 483         }
 484     } else if (i != -1) {
 485         x->ex_flags |= EXFLAG_INVALID;
 486     }
 487
 488     /* Handle extended key usage */
 489     x->ex_xkusage = 0;
 490     if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, &i, NULL)) != NULL) {
 491         x->ex_flags |= EXFLAG_XKUSAGE;
 492         for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 493             switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
 494             case NID_server_auth:
 495                 x->ex_xkusage |= XKU_SSL_SERVER;
 496                 break;
 497             case NID_client_auth:
 498                 x->ex_xkusage |= XKU_SSL_CLIENT;
 499                 break;
 500             case NID_email_protect:
 501                 x->ex_xkusage |= XKU_SMIME;
 502                 break;
 503             case NID_code_sign:
 504                 x->ex_xkusage |= XKU_CODE_SIGN;
 505                 break;
 506             case NID_ms_sgc:
 507             case NID_ns_sgc:
 508                 x->ex_xkusage |= XKU_SGC;
 509                 break;
 510             case NID_OCSP_sign:
 511                 x->ex_xkusage |= XKU_OCSP_SIGN;
 512                 break;
 513             case NID_time_stamp:
 514                 x->ex_xkusage |= XKU_TIMESTAMP;
 515                 break;
 516             case NID_dvcs:
 517                 x->ex_xkusage |= XKU_DVCS;
 518                 break;
 519             case NID_anyExtendedKeyUsage:
 520                 x->ex_xkusage |= XKU_ANYEKU;
 521                 break;
 522             default:
 523                 /* ignore unknown extended key usage */
 524                 break;
 525             }
 526         }
 527         sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 528     } else if (i != -1) {
 529         x->ex_flags |= EXFLAG_INVALID;
 530     }
 531
 532     /* Handle legacy Netscape extension */
 533     if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, &i, NULL)) != NULL) {
 534         if (ns->length > 0)
 535             x->ex_nscert = ns->data[0];
 536         else
 537             x->ex_nscert = 0;
 538         x->ex_flags |= EXFLAG_NSCERT;
 539         ASN1_BIT_STRING_free(ns);
 540     } else if (i != -1) {
 541         x->ex_flags |= EXFLAG_INVALID;
 542     }
 543
 544     /* Handle subject key identifier and issuer/authority key identifier */
 545     x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, &i, NULL);
 546     if (x->skid == NULL && i != -1)
 547         x->ex_flags |= EXFLAG_INVALID;
 548
 549     x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, &i, NULL);
 550     if (x->akid == NULL && i != -1)
 551         x->ex_flags |= EXFLAG_INVALID;
 552
 553     /* Check if subject name matches issuer */
 554     if (X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)) == 0) {
 555         x->ex_flags |= EXFLAG_SI; /* cert is self-issued */
 556         if (X509_check_akid(x, x->akid) == X509_V_OK /* SKID matches AKID */
 557                 /* .. and the signature alg matches the PUBKEY alg: */
 558                 && check_sig_alg_match(X509_get0_pubkey(x), x) == X509_V_OK)
 559             x->ex_flags |= EXFLAG_SS; /* indicate self-signed */
 560         /* This is very related to x509_likely_issued(x, x) == X509_V_OK */
 561     }
 562
 563     /* Handle subject alternative names and various other extensions */
 564     x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, &i, NULL);
 565     if (x->altname == NULL && i != -1)
 566         x->ex_flags |= EXFLAG_INVALID;
 567     x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
 568     if (x->nc == NULL && i != -1)
 569         x->ex_flags |= EXFLAG_INVALID;
 570
 571     /* Handle CRL distribution point entries */
 572     res = setup_crldp(x);
 573     if (res == 0)
 574         x->ex_flags |= EXFLAG_INVALID;
 575     else if (res < 0)
 576         goto err;
 577
 578 #ifndef OPENSSL_NO_RFC3779
 579     x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, &i, NULL);
 580     if (x->rfc3779_addr == NULL && i != -1)
 581         x->ex_flags |= EXFLAG_INVALID;
 582     x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum, &i, NULL);
 583     if (x->rfc3779_asid == NULL && i != -1)
 584         x->ex_flags |= EXFLAG_INVALID;
 585 #endif
 586     for (i = 0; i < X509_get_ext_count(x); i++) {
 587         X509_EXTENSION *ex = X509_get_ext(x, i);
 588         int nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 589
 590         if (nid == NID_freshest_crl)
 591             x->ex_flags |= EXFLAG_FRESHEST;
 592         if (!X509_EXTENSION_get_critical(ex))
 593             continue;
 594         if (!X509_supported_extension(ex)) {
 595             x->ex_flags |= EXFLAG_CRITICAL;
 596             break;
 597         }
 598         switch (nid) {
 599         case NID_basic_constraints:
 600             x->ex_flags |= EXFLAG_BCONS_CRITICAL;
 601             break;
 602         case NID_authority_key_identifier:
 603             x->ex_flags |= EXFLAG_AKID_CRITICAL;
 604             break;
 605         case NID_subject_key_identifier:
 606             x->ex_flags |= EXFLAG_SKID_CRITICAL;
 607             break;
 608         case NID_subject_alt_name:
 609             x->ex_flags |= EXFLAG_SAN_CRITICAL;
 610             break;
 611         default:
 612             break;
 613         }
 614     }
 615
 616     /* Set x->siginf, ignoring errors due to unsupported algos */
 617     (void)x509_init_sig_info(x);
 618
 619     x->ex_flags |= EXFLAG_SET; /* indicate that cert has been processed */
 620 #ifdef tsan_st_rel
 621     tsan_st_rel((TSAN_QUALIFIER int *)&x->ex_cached, 1);
 622     /*
 623      * Above store triggers fast lock-free check in the beginning of the
 624      * function. But one has to ensure that the structure is "stable", i.e.
 625      * all stores are visible on all processors. Hence the release fence.
 626      */
 627 #endif
 628     ERR_pop_to_mark();
 629     if ((x->ex_flags & EXFLAG_INVALID) == 0) {
 630         CRYPTO_THREAD_unlock(x->lock);
 631         return 1;
 632     }
 633     X509err(0, X509V3_R_INVALID_CERTIFICATE);
 634
 635  err:
 636     x->ex_flags |= EXFLAG_SET; /* indicate that cert has been processed */
 637     CRYPTO_THREAD_unlock(x->lock);
 638     return 0;
 639 }
 640
 641 /*-
 642  * CA checks common to all purposes
 643  * return codes:
 644  * 0 not a CA
 645  * 1 is a CA
 646  * 2 Only possible in older versions of openSSL when basicConstraints are absent
 647  *   new versions will not return this value. May be a CA
 648  * 3 basicConstraints absent but self-signed V1.
 649  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 650  * 5 Netscape specific CA Flags present
 651  */
 652
 653 static int check_ca(const X509 *x)
 654 {
 655     /* keyUsage if present should allow cert signing */
 656     if (ku_reject(x, KU_KEY_CERT_SIGN))
 657         return 0;
 658     if (x->ex_flags & EXFLAG_BCONS) {
 659         if (x->ex_flags & EXFLAG_CA)
 660             return 1;
 661         /* If basicConstraints says not a CA then say so */
 662         else
 663             return 0;
 664     } else {
 665         /* we support V1 roots for...  uh, I don't really know why. */
 666         if ((x->ex_flags & V1_ROOT) == V1_ROOT)
 667             return 3;
 668         /*
 669          * If key usage present it must have certSign so tolerate it
 670          */
 671         else if (x->ex_flags & EXFLAG_KUSAGE)
 672             return 4;
 673         /* Older certificates could have Netscape-specific CA types */
 674         else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
 675             return 5;
 676         /* can this still be regarded a CA certificate?  I doubt it */
 677         return 0;
 678     }
 679 }
 680
 681 void X509_set_proxy_flag(X509 *x)
 682 {
 683     x->ex_flags |= EXFLAG_PROXY;
 684 }
 685
 686 void X509_set_proxy_pathlen(X509 *x, long l)
 687 {
 688     x->ex_pcpathlen = l;
 689 }
 690
 691 int X509_check_ca(X509 *x)
 692 {
 693     /* Note 0 normally means "not a CA" - but in this case means error. */
 694     if (!x509v3_cache_extensions(x))
 695         return 0;
 696
 697     return check_ca(x);
 698 }
 699
 700 /* Check SSL CA: common checks for SSL client and server */
 701 static int check_ssl_ca(const X509 *x)
 702 {
 703     int ca_ret;
 704     ca_ret = check_ca(x);
 705     if (!ca_ret)
 706         return 0;
 707     /* check nsCertType if present */
 708     if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
 709         return ca_ret;
 710     else
 711         return 0;
 712 }
 713
 714 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
 715                                     int ca)
 716 {
 717     if (xku_reject(x, XKU_SSL_CLIENT))
 718         return 0;
 719     if (ca)
 720         return check_ssl_ca(x);
 721     /* We need to do digital signatures or key agreement */
 722     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
 723         return 0;
 724     /* nsCertType if present should allow SSL client use */
 725     if (ns_reject(x, NS_SSL_CLIENT))
 726         return 0;
 727     return 1;
 728 }
 729
 730 /*
 731  * Key usage needed for TLS/SSL server: digital signature, encipherment or
 732  * key agreement. The ssl code can check this more thoroughly for individual
 733  * key types.
 734  */
 735 #define KU_TLS \
 736         KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT
 737
 738 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 739                                     int ca)
 740 {
 741     if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
 742         return 0;
 743     if (ca)
 744         return check_ssl_ca(x);
 745
 746     if (ns_reject(x, NS_SSL_SERVER))
 747         return 0;
 748     if (ku_reject(x, KU_TLS))
 749         return 0;
 750
 751     return 1;
 752
 753 }
 754
 755 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 756                                        int ca)
 757 {
 758     int ret;
 759     ret = check_purpose_ssl_server(xp, x, ca);
 760     if (!ret || ca)
 761         return ret;
 762     /* We need to encipher or Netscape complains */
 763     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 764         return 0;
 765     return ret;
 766 }
 767
 768 /* common S/MIME checks */
 769 static int purpose_smime(const X509 *x, int ca)
 770 {
 771     if (xku_reject(x, XKU_SMIME))
 772         return 0;
 773     if (ca) {
 774         int ca_ret;
 775         ca_ret = check_ca(x);
 776         if (!ca_ret)
 777             return 0;
 778         /* check nsCertType if present */
 779         if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
 780             return ca_ret;
 781         else
 782             return 0;
 783     }
 784     if (x->ex_flags & EXFLAG_NSCERT) {
 785         if (x->ex_nscert & NS_SMIME)
 786             return 1;
 787         /* Workaround for some buggy certificates */
 788         if (x->ex_nscert & NS_SSL_CLIENT)
 789             return 2;
 790         return 0;
 791     }
 792     return 1;
 793 }
 794
 795 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
 796                                     int ca)
 797 {
 798     int ret;
 799     ret = purpose_smime(x, ca);
 800     if (!ret || ca)
 801         return ret;
 802     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION))
 803         return 0;
 804     return ret;
 805 }
 806
 807 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
 808                                        int ca)
 809 {
 810     int ret;
 811     ret = purpose_smime(x, ca);
 812     if (!ret || ca)
 813         return ret;
 814     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 815         return 0;
 816     return ret;
 817 }
 818
 819 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
 820                                   int ca)
 821 {
 822     if (ca) {
 823         int ca_ret;
 824         if ((ca_ret = check_ca(x)) != 2)
 825             return ca_ret;
 826         else
 827             return 0;
 828     }
 829     if (ku_reject(x, KU_CRL_SIGN))
 830         return 0;
 831     return 1;
 832 }
 833
 834 /*
 835  * OCSP helper: this is *not* a full OCSP check. It just checks that each CA
 836  * is valid. Additional checks must be made on the chain.
 837  */
 838
 839 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 840 {
 841     /*
 842      * Must be a valid CA.  Should we really support the "I don't know" value
 843      * (2)?
 844      */
 845     if (ca)
 846         return check_ca(x);
 847     /* leaf certificate is checked in OCSP_verify() */
 848     return 1;
 849 }
 850
 851 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
 852                                         int ca)
 853 {
 854     int i_ext;
 855
 856     /* If ca is true we must return if this is a valid CA certificate. */
 857     if (ca)
 858         return check_ca(x);
 859
 860     /*
 861      * Check the optional key usage field:
 862      * if Key Usage is present, it must be one of digitalSignature
 863      * and/or nonRepudiation (other values are not consistent and shall
 864      * be rejected).
 865      */
 866     if ((x->ex_flags & EXFLAG_KUSAGE)
 867         && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
 868             !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
 869         return 0;
 870
 871     /* Only time stamp key usage is permitted and it's required. */
 872     if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
 873         return 0;
 874
 875     /* Extended Key Usage MUST be critical */
 876     i_ext = X509_get_ext_by_NID(x, NID_ext_key_usage, -1);
 877     if (i_ext >= 0) {
 878         X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
 879         if (!X509_EXTENSION_get_critical(ext))
 880             return 0;
 881     }
 882
 883     return 1;
 884 }
 885
 886 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 887 {
 888     return 1;
 889 }
 890
 891 /*-
 892  * Various checks to see if one certificate potentially issued the second.
 893  * This can be used to prune a set of possible issuer certificates which
 894  * have been looked up using some simple method such as by subject name.
 895  * These are:
 896  * 1. Check issuer_name(subject) == subject_name(issuer)
 897  * 2. If akid(subject) exists, check that it matches issuer
 898  * 3. Check that issuer public key algorithm matches subject signature algorithm
 899  * 4. Check that any key_usage(issuer) allows certificate signing
 900  * Note that this does not include actually checking the signature.
 901  * Returns 0 for OK, or positive for reason for mismatch
 902  * where reason codes match those for X509_verify_cert().
 903  */
 904 int X509_check_issued(X509 *issuer, X509 *subject)
 905 {
 906     int ret;
 907
 908     if ((ret = x509_likely_issued(issuer, subject)) != X509_V_OK)
 909         return ret;
 910     return x509_signing_allowed(issuer, subject);
 911 }
 912
 913 /* do the checks 1., 2., and 3. as described above for X509_check_issued() */
 914 int x509_likely_issued(X509 *issuer, X509 *subject)
 915 {
 916     int ret;
 917
 918     if (X509_NAME_cmp(X509_get_subject_name(issuer),
 919                       X509_get_issuer_name(subject)) != 0)
 920         return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 921
 922     /* set issuer->skid and subject->akid */
 923     if (!x509v3_cache_extensions(issuer)
 924             || !x509v3_cache_extensions(subject))
 925         return X509_V_ERR_UNSPECIFIED;
 926
 927     ret = X509_check_akid(issuer, subject->akid);
 928     if (ret != X509_V_OK)
 929         return ret;
 930
 931     /* check if the subject signature alg matches the issuer's PUBKEY alg */
 932     return check_sig_alg_match(X509_get0_pubkey(issuer), subject);
 933 }
 934
 935 /*-
 936  * Check if certificate I<issuer> is allowed to issue certificate I<subject>
 937  * according to the B<keyUsage> field of I<issuer> if present
 938  * depending on any proxyCertInfo extension of I<subject>.
 939  * Returns 0 for OK, or positive for reason for rejection
 940  * where reason codes match those for X509_verify_cert().
 941  */
 942 int x509_signing_allowed(const X509 *issuer, const X509 *subject)
 943 {
 944     if (subject->ex_flags & EXFLAG_PROXY) {
 945         if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 946             return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 947     } else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
 948         return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 949     return X509_V_OK;
 950 }
 951
 952 int X509_check_akid(const X509 *issuer, const AUTHORITY_KEYID *akid)
 953 {
 954     if (akid == NULL)
 955         return X509_V_OK;
 956
 957     /* Check key ids (if present) */
 958     if (akid->keyid && issuer->skid &&
 959         ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid))
 960         return X509_V_ERR_AKID_SKID_MISMATCH;
 961     /* Check serial number */
 962     if (akid->serial &&
 963         ASN1_INTEGER_cmp(X509_get0_serialNumber(issuer), akid->serial))
 964         return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 965     /* Check issuer name */
 966     if (akid->issuer) {
 967         /*
 968          * Ugh, for some peculiar reason AKID includes SEQUENCE OF
 969          * GeneralName. So look for a DirName. There may be more than one but
 970          * we only take any notice of the first.
 971          */
 972         GENERAL_NAMES *gens;
 973         GENERAL_NAME *gen;
 974         X509_NAME *nm = NULL;
 975         int i;
 976         gens = akid->issuer;
 977         for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 978             gen = sk_GENERAL_NAME_value(gens, i);
 979             if (gen->type == GEN_DIRNAME) {
 980                 nm = gen->d.dirn;
 981                 break;
 982             }
 983         }
 984         if (nm != NULL && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)) != 0)
 985             return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 986     }
 987     return X509_V_OK;
 988 }
 989
 990 uint32_t X509_get_extension_flags(X509 *x)
 991 {
 992     /* Call for side-effect of computing hash and caching extensions */
 993     X509_check_purpose(x, -1, -1);
 994     return x->ex_flags;
 995 }
 996
 997 uint32_t X509_get_key_usage(X509 *x)
 998 {
 999     /* Call for side-effect of computing hash and caching extensions */
1000     if (X509_check_purpose(x, -1, -1) != 1)
1001         return 0;
1002     if (x->ex_flags & EXFLAG_KUSAGE)
1003         return x->ex_kusage;
1004     return UINT32_MAX;
1005 }
1006
1007 uint32_t X509_get_extended_key_usage(X509 *x)
1008 {
1009     /* Call for side-effect of computing hash and caching extensions */
1010     if (X509_check_purpose(x, -1, -1) != 1)
1011         return 0;
1012     if (x->ex_flags & EXFLAG_XKUSAGE)
1013         return x->ex_xkusage;
1014     return UINT32_MAX;
1015 }
1016
1017 const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x)
1018 {
1019     /* Call for side-effect of computing hash and caching extensions */
1020     if (X509_check_purpose(x, -1, -1) != 1)
1021         return NULL;
1022     return x->skid;
1023 }
1024
1025 const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x)
1026 {
1027     /* Call for side-effect of computing hash and caching extensions */
1028     if (X509_check_purpose(x, -1, -1) != 1)
1029         return NULL;
1030     return (x->akid != NULL ? x->akid->keyid : NULL);
1031 }
1032
1033 const GENERAL_NAMES *X509_get0_authority_issuer(X509 *x)
1034 {
1035     /* Call for side-effect of computing hash and caching extensions */
1036     if (X509_check_purpose(x, -1, -1) != 1)
1037         return NULL;
1038     return (x->akid != NULL ? x->akid->issuer : NULL);
1039 }
1040
1041 const ASN1_INTEGER *X509_get0_authority_serial(X509 *x)
1042 {
1043     /* Call for side-effect of computing hash and caching extensions */
1044     if (X509_check_purpose(x, -1, -1) != 1)
1045         return NULL;
1046     return (x->akid != NULL ? x->akid->serial : NULL);
1047 }
1048
1049 long X509_get_pathlen(X509 *x)
1050 {
1051     /* Called for side effect of caching extensions */
1052     if (X509_check_purpose(x, -1, -1) != 1
1053             || (x->ex_flags & EXFLAG_BCONS) == 0)
1054         return -1;
1055     return x->ex_pathlen;
1056 }
1057
1058 long X509_get_proxy_pathlen(X509 *x)
1059 {
1060     /* Called for side effect of caching extensions */
1061     if (X509_check_purpose(x, -1, -1) != 1
1062             || (x->ex_flags & EXFLAG_PROXY) == 0)
1063         return -1;
1064     return x->ex_pcpathlen;
1065 }