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 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
  82     if (!x509v3_cache_extensions(x))
  83         return -1;
  84
  85     /* Return if side-effect only call */
  86     if (id == -1)
  87         return 1;
  88     idx = X509_PURPOSE_get_by_id(id);
  89     if (idx == -1)
  90         return -1;
  91     pt = X509_PURPOSE_get0(idx);
  92     return pt->check_purpose(pt, x, ca);
  93 }
  94
  95 int X509_PURPOSE_set(int *p, int purpose)
  96 {
  97     if (X509_PURPOSE_get_by_id(purpose) == -1) {
  98         X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
  99         return 0;
 100     }
 101     *p = purpose;
 102     return 1;
 103 }
 104
 105 int X509_PURPOSE_get_count(void)
 106 {
 107     if (!xptable)
 108         return X509_PURPOSE_COUNT;
 109     return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
 110 }
 111
 112 X509_PURPOSE *X509_PURPOSE_get0(int idx)
 113 {
 114     if (idx < 0)
 115         return NULL;
 116     if (idx < (int)X509_PURPOSE_COUNT)
 117         return xstandard + idx;
 118     return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
 119 }
 120
 121 int X509_PURPOSE_get_by_sname(const char *sname)
 122 {
 123     int i;
 124     X509_PURPOSE *xptmp;
 125     for (i = 0; i < X509_PURPOSE_get_count(); i++) {
 126         xptmp = X509_PURPOSE_get0(i);
 127         if (strcmp(xptmp->sname, sname) == 0)
 128             return i;
 129     }
 130     return -1;
 131 }
 132
 133 int X509_PURPOSE_get_by_id(int purpose)
 134 {
 135     X509_PURPOSE tmp;
 136     int idx;
 137
 138     if ((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
 139         return purpose - X509_PURPOSE_MIN;
 140     if (xptable == NULL)
 141         return -1;
 142     tmp.purpose = purpose;
 143     idx = sk_X509_PURPOSE_find(xptable, &tmp);
 144     if (idx < 0)
 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                      const char *name, const 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 == NULL|| ptmp->sname == NULL) {
 182         X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 183         goto err;
 184     }
 185     /* Keep the dynamic flag of existing entry */
 186     ptmp->flags &= X509_PURPOSE_DYNAMIC;
 187     /* Set all other flags */
 188     ptmp->flags |= flags;
 189
 190     ptmp->purpose = id;
 191     ptmp->trust = trust;
 192     ptmp->check_purpose = ck;
 193     ptmp->usr_data = arg;
 194
 195     /* If its a new entry manage the dynamic table */
 196     if (idx == -1) {
 197         if (xptable == NULL
 198             && (xptable = sk_X509_PURPOSE_new(xp_cmp)) == NULL) {
 199             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 200             goto err;
 201         }
 202         if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
 203             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 204             goto err;
 205         }
 206     }
 207     return 1;
 208  err:
 209     if (idx == -1) {
 210         OPENSSL_free(ptmp->name);
 211         OPENSSL_free(ptmp->sname);
 212         OPENSSL_free(ptmp);
 213     }
 214     return 0;
 215 }
 216
 217 static void xptable_free(X509_PURPOSE *p)
 218 {
 219     if (p == NULL)
 220         return;
 221     if (p->flags & X509_PURPOSE_DYNAMIC) {
 222         if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
 223             OPENSSL_free(p->name);
 224             OPENSSL_free(p->sname);
 225         }
 226         OPENSSL_free(p);
 227     }
 228 }
 229
 230 void X509_PURPOSE_cleanup(void)
 231 {
 232     sk_X509_PURPOSE_pop_free(xptable, xptable_free);
 233     xptable = NULL;
 234 }
 235
 236 int X509_PURPOSE_get_id(const X509_PURPOSE *xp)
 237 {
 238     return xp->purpose;
 239 }
 240
 241 char *X509_PURPOSE_get0_name(const X509_PURPOSE *xp)
 242 {
 243     return xp->name;
 244 }
 245
 246 char *X509_PURPOSE_get0_sname(const X509_PURPOSE *xp)
 247 {
 248     return xp->sname;
 249 }
 250
 251 int X509_PURPOSE_get_trust(const X509_PURPOSE *xp)
 252 {
 253     return xp->trust;
 254 }
 255
 256 static int nid_cmp(const int *a, const int *b)
 257 {
 258     return *a - *b;
 259 }
 260
 261 DECLARE_OBJ_BSEARCH_CMP_FN(int, int, nid);
 262 IMPLEMENT_OBJ_BSEARCH_CMP_FN(int, int, nid);
 263
 264 int X509_supported_extension(X509_EXTENSION *ex)
 265 {
 266     /*
 267      * This table is a list of the NIDs of supported extensions: that is
 268      * those which are used by the verify process. If an extension is
 269      * critical and doesn't appear in this list then the verify process will
 270      * normally reject the certificate. The list must be kept in numerical
 271      * order because it will be searched using bsearch.
 272      */
 273
 274     static const int supported_nids[] = {
 275         NID_netscape_cert_type, /* 71 */
 276         NID_key_usage,          /* 83 */
 277         NID_subject_alt_name,   /* 85 */
 278         NID_basic_constraints,  /* 87 */
 279         NID_certificate_policies, /* 89 */
 280         NID_crl_distribution_points, /* 103 */
 281         NID_ext_key_usage,      /* 126 */
 282 #ifndef OPENSSL_NO_RFC3779
 283         NID_sbgp_ipAddrBlock,   /* 290 */
 284         NID_sbgp_autonomousSysNum, /* 291 */
 285 #endif
 286         NID_policy_constraints, /* 401 */
 287         NID_proxyCertInfo,      /* 663 */
 288         NID_name_constraints,   /* 666 */
 289         NID_policy_mappings,    /* 747 */
 290         NID_inhibit_any_policy  /* 748 */
 291     };
 292
 293     int ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 294
 295     if (ex_nid == NID_undef)
 296         return 0;
 297
 298     if (OBJ_bsearch_nid(&ex_nid, supported_nids, OSSL_NELEM(supported_nids)))
 299         return 1;
 300     return 0;
 301 }
 302
 303 /* return 1 on success, 0 if x is invalid, -1 on (internal) error */
 304 static int setup_dp(const X509 *x, DIST_POINT *dp)
 305 {
 306     const X509_NAME *iname = NULL;
 307     int i;
 308
 309     if (dp->distpoint == NULL && sk_GENERAL_NAME_num(dp->CRLissuer) <= 0) {
 310         X509err(0, X509_R_INVALID_DISTPOINT);
 311         return 0;
 312     }
 313     if (dp->reasons != NULL) {
 314         if (dp->reasons->length > 0)
 315             dp->dp_reasons = dp->reasons->data[0];
 316         if (dp->reasons->length > 1)
 317             dp->dp_reasons |= (dp->reasons->data[1] << 8);
 318         dp->dp_reasons &= CRLDP_ALL_REASONS;
 319     } else {
 320         dp->dp_reasons = CRLDP_ALL_REASONS;
 321     }
 322     if (dp->distpoint == NULL || dp->distpoint->type != 1)
 323         return 1;
 324
 325     /* handle name fragment given by nameRelativeToCRLIssuer */
 326     /*
 327      * Note that the below way of determining iname is not really compliant
 328      * with https://tools.ietf.org/html/rfc5280#section-4.2.1.13
 329      * According to it, sk_GENERAL_NAME_num(dp->CRLissuer) MUST be <= 1
 330      * and any CRLissuer could be of type different to GEN_DIRNAME.
 331      */
 332     for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
 333         GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
 334
 335         if (gen->type == GEN_DIRNAME) {
 336             iname = gen->d.directoryName;
 337             break;
 338         }
 339     }
 340     if (iname == NULL)
 341         iname = X509_get_issuer_name(x);
 342     return DIST_POINT_set_dpname(dp->distpoint, iname) ? 1 : -1;
 343 }
 344
 345 /* return 1 on success, 0 if x is invalid, -1 on (internal) error */
 346 static int setup_crldp(X509 *x)
 347 {
 348     int i;
 349
 350     x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &i, NULL);
 351     if (x->crldp == NULL && i != -1)
 352         return 0;
 353
 354     for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) {
 355         int res = setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
 356
 357         if (res < 1)
 358             return res;
 359     }
 360     return 1;
 361 }
 362
 363 /* Check that issuer public key algorithm matches subject signature algorithm */
 364 static int check_sig_alg_match(const EVP_PKEY *pkey, const X509 *subject)
 365 {
 366     int pkey_nid;
 367
 368     if (pkey == NULL)
 369         return X509_V_ERR_NO_ISSUER_PUBLIC_KEY;
 370     if (OBJ_find_sigid_algs(OBJ_obj2nid(subject->cert_info.signature.algorithm),
 371                             NULL, &pkey_nid) == 0)
 372         return X509_V_ERR_UNSUPPORTED_SIGNATURE_ALGORITHM;
 373     if (EVP_PKEY_type(pkey_nid) != EVP_PKEY_base_id(pkey))
 374         return X509_V_ERR_SIGNATURE_ALGORITHM_MISMATCH;
 375     return X509_V_OK;
 376 }
 377
 378 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 379 #define ku_reject(x, usage) \
 380         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 381 #define xku_reject(x, usage) \
 382         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 383 #define ns_reject(x, usage) \
 384         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 385
 386 /*
 387  * Cache info on various X.509v3 extensions and further derived information,
 388  * e.g., if cert 'x' is self-issued, in x->ex_flags and other internal fields.
 389  * X509_SIG_INFO_VALID is set in x->flags if x->siginf was filled successfully.
 390  * Set EXFLAG_INVALID and return 0 in case the certificate is invalid.
 391  */
 392 int x509v3_cache_extensions(X509 *x)
 393 {
 394     BASIC_CONSTRAINTS *bs;
 395     PROXY_CERT_INFO_EXTENSION *pci;
 396     ASN1_BIT_STRING *usage;
 397     ASN1_BIT_STRING *ns;
 398     EXTENDED_KEY_USAGE *extusage;
 399     int i;
 400     int res;
 401
 402 #ifdef tsan_ld_acq
 403     /* fast lock-free check, see end of the function for details. */
 404     if (tsan_ld_acq((TSAN_QUALIFIER int *)&x->ex_cached))
 405         return (x->ex_flags & EXFLAG_INVALID) == 0;
 406 #endif
 407
 408     CRYPTO_THREAD_write_lock(x->lock);
 409     if (x->ex_flags & EXFLAG_SET) { /* cert has already been processed */
 410         CRYPTO_THREAD_unlock(x->lock);
 411         return (x->ex_flags & EXFLAG_INVALID) == 0;
 412     }
 413     ERR_set_mark();
 414
 415     /* Cache the SHA1 digest of the cert */
 416     if (!X509_digest(x, EVP_sha1(), x->sha1_hash, NULL))
 417         /*
 418          * Note that the cert is marked invalid also on internal malloc failure
 419          * or on failure of EVP_MD_fetch(), potentially called by X509_digest().
 420          */
 421         x->ex_flags |= EXFLAG_INVALID;
 422
 423     /* V1 should mean no extensions ... */
 424     if (X509_get_version(x) == 0)
 425         x->ex_flags |= EXFLAG_V1;
 426
 427     /* Handle basic constraints */
 428     x->ex_pathlen = -1;
 429     if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, &i, NULL)) != NULL) {
 430         if (bs->ca)
 431             x->ex_flags |= EXFLAG_CA;
 432         if (bs->pathlen != NULL) {
 433             /*
 434              * the error case !bs->ca is checked by check_chain_extensions()
 435              * in case ctx->param->flags & X509_V_FLAG_X509_STRICT
 436              */
 437             if (bs->pathlen->type == V_ASN1_NEG_INTEGER) {
 438                 X509err(0, X509V3_R_NEGATIVE_PATHLEN);
 439                 x->ex_flags |= EXFLAG_INVALID;
 440             } else {
 441                 x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 442             }
 443         }
 444         BASIC_CONSTRAINTS_free(bs);
 445         x->ex_flags |= EXFLAG_BCONS;
 446     } else if (i != -1) {
 447         x->ex_flags |= EXFLAG_INVALID;
 448     }
 449
 450     /* Handle proxy certificates */
 451     if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, &i, NULL)) != NULL) {
 452         if (x->ex_flags & EXFLAG_CA
 453             || X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
 454             || X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
 455             x->ex_flags |= EXFLAG_INVALID;
 456         }
 457         if (pci->pcPathLengthConstraint != NULL)
 458             x->ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 459         else
 460             x->ex_pcpathlen = -1;
 461         PROXY_CERT_INFO_EXTENSION_free(pci);
 462         x->ex_flags |= EXFLAG_PROXY;
 463     } else if (i != -1) {
 464         x->ex_flags |= EXFLAG_INVALID;
 465     }
 466
 467     /* Handle (basic) key usage */
 468     if ((usage = X509_get_ext_d2i(x, NID_key_usage, &i, NULL)) != NULL) {
 469         x->ex_kusage = 0;
 470         if (usage->length > 0) {
 471             x->ex_kusage = usage->data[0];
 472             if (usage->length > 1)
 473                 x->ex_kusage |= usage->data[1] << 8;
 474         }
 475         x->ex_flags |= EXFLAG_KUSAGE;
 476         ASN1_BIT_STRING_free(usage);
 477         /* Check for empty key usage according to RFC 5280 section 4.2.1.3 */
 478         if (x->ex_kusage == 0) {
 479             X509err(0, X509V3_R_EMPTY_KEY_USAGE);
 480             x->ex_flags |= EXFLAG_INVALID;
 481         }
 482     } else if (i != -1) {
 483         x->ex_flags |= EXFLAG_INVALID;
 484     }
 485
 486     /* Handle extended key usage */
 487     x->ex_xkusage = 0;
 488     if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, &i, NULL)) != NULL) {
 489         x->ex_flags |= EXFLAG_XKUSAGE;
 490         for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 491             switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
 492             case NID_server_auth:
 493                 x->ex_xkusage |= XKU_SSL_SERVER;
 494                 break;
 495             case NID_client_auth:
 496                 x->ex_xkusage |= XKU_SSL_CLIENT;
 497                 break;
 498             case NID_email_protect:
 499                 x->ex_xkusage |= XKU_SMIME;
 500                 break;
 501             case NID_code_sign:
 502                 x->ex_xkusage |= XKU_CODE_SIGN;
 503                 break;
 504             case NID_ms_sgc:
 505             case NID_ns_sgc:
 506                 x->ex_xkusage |= XKU_SGC;
 507                 break;
 508             case NID_OCSP_sign:
 509                 x->ex_xkusage |= XKU_OCSP_SIGN;
 510                 break;
 511             case NID_time_stamp:
 512                 x->ex_xkusage |= XKU_TIMESTAMP;
 513                 break;
 514             case NID_dvcs:
 515                 x->ex_xkusage |= XKU_DVCS;
 516                 break;
 517             case NID_anyExtendedKeyUsage:
 518                 x->ex_xkusage |= XKU_ANYEKU;
 519                 break;
 520             default:
 521                 /* ignore unknown extended key usage */
 522                 break;
 523             }
 524         }
 525         sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 526     } else if (i != -1) {
 527         x->ex_flags |= EXFLAG_INVALID;
 528     }
 529
 530     /* Handle legacy Netscape extension */
 531     if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, &i, NULL)) != NULL) {
 532         if (ns->length > 0)
 533             x->ex_nscert = ns->data[0];
 534         else
 535             x->ex_nscert = 0;
 536         x->ex_flags |= EXFLAG_NSCERT;
 537         ASN1_BIT_STRING_free(ns);
 538     } else if (i != -1) {
 539         x->ex_flags |= EXFLAG_INVALID;
 540     }
 541
 542     /* Handle subject key identifier and issuer/authority key identifier */
 543     x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, &i, NULL);
 544     if (x->skid == NULL && i != -1)
 545         x->ex_flags |= EXFLAG_INVALID;
 546
 547     x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, &i, NULL);
 548     if (x->akid == NULL && i != -1)
 549         x->ex_flags |= EXFLAG_INVALID;
 550
 551     /* Check if subject name matches issuer */
 552     if (X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)) == 0) {
 553         x->ex_flags |= EXFLAG_SI; /* cert is self-issued */
 554         if (X509_check_akid(x, x->akid) == X509_V_OK /* SKID matches AKID */
 555                 /* .. and the signature alg matches the PUBKEY alg: */
 556                 && check_sig_alg_match(X509_get0_pubkey(x), x) == X509_V_OK)
 557             x->ex_flags |= EXFLAG_SS; /* indicate self-signed */
 558         /* This is very related to x509_likely_issued(x, x) == X509_V_OK */
 559     }
 560
 561     /* Handle subject alternative names and various other extensions */
 562     x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, &i, NULL);
 563     if (x->altname == NULL && i != -1)
 564         x->ex_flags |= EXFLAG_INVALID;
 565     x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
 566     if (x->nc == NULL && i != -1)
 567         x->ex_flags |= EXFLAG_INVALID;
 568
 569     /* Handle CRL distribution point entries */
 570     res = setup_crldp(x);
 571     if (res == 0)
 572         x->ex_flags |= EXFLAG_INVALID;
 573     else if (res < 0)
 574         goto err;
 575
 576 #ifndef OPENSSL_NO_RFC3779
 577     x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, &i, NULL);
 578     if (x->rfc3779_addr == NULL && i != -1)
 579         x->ex_flags |= EXFLAG_INVALID;
 580     x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum, &i, NULL);
 581     if (x->rfc3779_asid == NULL && i != -1)
 582         x->ex_flags |= EXFLAG_INVALID;
 583 #endif
 584     for (i = 0; i < X509_get_ext_count(x); i++) {
 585         X509_EXTENSION *ex = X509_get_ext(x, i);
 586         int nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
 587
 588         if (nid == NID_freshest_crl)
 589             x->ex_flags |= EXFLAG_FRESHEST;
 590         if (!X509_EXTENSION_get_critical(ex))
 591             continue;
 592         if (!X509_supported_extension(ex)) {
 593             x->ex_flags |= EXFLAG_CRITICAL;
 594             break;
 595         }
 596         switch (nid) {
 597         case NID_basic_constraints:
 598             x->ex_flags |= EXFLAG_BCONS_CRITICAL;
 599             break;
 600         case NID_authority_key_identifier:
 601             x->ex_flags |= EXFLAG_AKID_CRITICAL;
 602             break;
 603         case NID_subject_key_identifier:
 604             x->ex_flags |= EXFLAG_SKID_CRITICAL;
 605             break;
 606         case NID_subject_alt_name:
 607             x->ex_flags |= EXFLAG_SAN_CRITICAL;
 608             break;
 609         default:
 610             break;
 611         }
 612     }
 613
 614     /* Set x->siginf, ignoring errors due to unsupported algos */
 615     (void)x509_init_sig_info(x);
 616
 617     x->ex_flags |= EXFLAG_SET; /* indicate that cert has been processed */
 618 #ifdef tsan_st_rel
 619     tsan_st_rel((TSAN_QUALIFIER int *)&x->ex_cached, 1);
 620     /*
 621      * Above store triggers fast lock-free check in the beginning of the
 622      * function. But one has to ensure that the structure is "stable", i.e.
 623      * all stores are visible on all processors. Hence the release fence.
 624      */
 625 #endif
 626     ERR_pop_to_mark();
 627     if ((x->ex_flags & EXFLAG_INVALID) == 0) {
 628         CRYPTO_THREAD_unlock(x->lock);
 629         return 1;
 630     }
 631     X509err(0, X509V3_R_INVALID_CERTIFICATE);
 632
 633  err:
 634     x->ex_flags |= EXFLAG_SET; /* indicate that cert has been processed */
 635     CRYPTO_THREAD_unlock(x->lock);
 636     return 0;
 637 }
 638
 639 /*-
 640  * CA checks common to all purposes
 641  * return codes:
 642  * 0 not a CA
 643  * 1 is a CA
 644  * 2 Only possible in older versions of openSSL when basicConstraints are absent
 645  *   new versions will not return this value. May be a CA
 646  * 3 basicConstraints absent but self-signed V1.
 647  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 648  * 5 Netscape specific CA Flags present
 649  */
 650
 651 static int check_ca(const X509 *x)
 652 {
 653     /* keyUsage if present should allow cert signing */
 654     if (ku_reject(x, KU_KEY_CERT_SIGN))
 655         return 0;
 656     if (x->ex_flags & EXFLAG_BCONS) {
 657         if (x->ex_flags & EXFLAG_CA)
 658             return 1;
 659         /* If basicConstraints says not a CA then say so */
 660         else
 661             return 0;
 662     } else {
 663         /* we support V1 roots for...  uh, I don't really know why. */
 664         if ((x->ex_flags & V1_ROOT) == V1_ROOT)
 665             return 3;
 666         /*
 667          * If key usage present it must have certSign so tolerate it
 668          */
 669         else if (x->ex_flags & EXFLAG_KUSAGE)
 670             return 4;
 671         /* Older certificates could have Netscape-specific CA types */
 672         else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
 673             return 5;
 674         /* can this still be regarded a CA certificate?  I doubt it */
 675         return 0;
 676     }
 677 }
 678
 679 void X509_set_proxy_flag(X509 *x)
 680 {
 681     x->ex_flags |= EXFLAG_PROXY;
 682 }
 683
 684 void X509_set_proxy_pathlen(X509 *x, long l)
 685 {
 686     x->ex_pcpathlen = l;
 687 }
 688
 689 int X509_check_ca(X509 *x)
 690 {
 691     /* Note 0 normally means "not a CA" - but in this case means error. */
 692     if (!x509v3_cache_extensions(x))
 693         return 0;
 694
 695     return check_ca(x);
 696 }
 697
 698 /* Check SSL CA: common checks for SSL client and server */
 699 static int check_ssl_ca(const X509 *x)
 700 {
 701     int ca_ret;
 702     ca_ret = check_ca(x);
 703     if (!ca_ret)
 704         return 0;
 705     /* check nsCertType if present */
 706     if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
 707         return ca_ret;
 708     else
 709         return 0;
 710 }
 711
 712 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
 713                                     int ca)
 714 {
 715     if (xku_reject(x, XKU_SSL_CLIENT))
 716         return 0;
 717     if (ca)
 718         return check_ssl_ca(x);
 719     /* We need to do digital signatures or key agreement */
 720     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
 721         return 0;
 722     /* nsCertType if present should allow SSL client use */
 723     if (ns_reject(x, NS_SSL_CLIENT))
 724         return 0;
 725     return 1;
 726 }
 727
 728 /*
 729  * Key usage needed for TLS/SSL server: digital signature, encipherment or
 730  * key agreement. The ssl code can check this more thoroughly for individual
 731  * key types.
 732  */
 733 #define KU_TLS \
 734         KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT
 735
 736 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 737                                     int ca)
 738 {
 739     if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
 740         return 0;
 741     if (ca)
 742         return check_ssl_ca(x);
 743
 744     if (ns_reject(x, NS_SSL_SERVER))
 745         return 0;
 746     if (ku_reject(x, KU_TLS))
 747         return 0;
 748
 749     return 1;
 750
 751 }
 752
 753 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 754                                        int ca)
 755 {
 756     int ret;
 757     ret = check_purpose_ssl_server(xp, x, ca);
 758     if (!ret || ca)
 759         return ret;
 760     /* We need to encipher or Netscape complains */
 761     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 762         return 0;
 763     return ret;
 764 }
 765
 766 /* common S/MIME checks */
 767 static int purpose_smime(const X509 *x, int ca)
 768 {
 769     if (xku_reject(x, XKU_SMIME))
 770         return 0;
 771     if (ca) {
 772         int ca_ret;
 773         ca_ret = check_ca(x);
 774         if (!ca_ret)
 775             return 0;
 776         /* check nsCertType if present */
 777         if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
 778             return ca_ret;
 779         else
 780             return 0;
 781     }
 782     if (x->ex_flags & EXFLAG_NSCERT) {
 783         if (x->ex_nscert & NS_SMIME)
 784             return 1;
 785         /* Workaround for some buggy certificates */
 786         if (x->ex_nscert & NS_SSL_CLIENT)
 787             return 2;
 788         return 0;
 789     }
 790     return 1;
 791 }
 792
 793 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
 794                                     int ca)
 795 {
 796     int ret;
 797     ret = purpose_smime(x, ca);
 798     if (!ret || ca)
 799         return ret;
 800     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION))
 801         return 0;
 802     return ret;
 803 }
 804
 805 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
 806                                        int ca)
 807 {
 808     int ret;
 809     ret = purpose_smime(x, ca);
 810     if (!ret || ca)
 811         return ret;
 812     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 813         return 0;
 814     return ret;
 815 }
 816
 817 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
 818                                   int ca)
 819 {
 820     if (ca) {
 821         int ca_ret;
 822         if ((ca_ret = check_ca(x)) != 2)
 823             return ca_ret;
 824         else
 825             return 0;
 826     }
 827     if (ku_reject(x, KU_CRL_SIGN))
 828         return 0;
 829     return 1;
 830 }
 831
 832 /*
 833  * OCSP helper: this is *not* a full OCSP check. It just checks that each CA
 834  * is valid. Additional checks must be made on the chain.
 835  */
 836
 837 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 838 {
 839     /*
 840      * Must be a valid CA.  Should we really support the "I don't know" value
 841      * (2)?
 842      */
 843     if (ca)
 844         return check_ca(x);
 845     /* leaf certificate is checked in OCSP_verify() */
 846     return 1;
 847 }
 848
 849 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
 850                                         int ca)
 851 {
 852     int i_ext;
 853
 854     /* If ca is true we must return if this is a valid CA certificate. */
 855     if (ca)
 856         return check_ca(x);
 857
 858     /*
 859      * Check the optional key usage field:
 860      * if Key Usage is present, it must be one of digitalSignature
 861      * and/or nonRepudiation (other values are not consistent and shall
 862      * be rejected).
 863      */
 864     if ((x->ex_flags & EXFLAG_KUSAGE)
 865         && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
 866             !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
 867         return 0;
 868
 869     /* Only time stamp key usage is permitted and it's required. */
 870     if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
 871         return 0;
 872
 873     /* Extended Key Usage MUST be critical */
 874     i_ext = X509_get_ext_by_NID(x, NID_ext_key_usage, -1);
 875     if (i_ext >= 0) {
 876         X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
 877         if (!X509_EXTENSION_get_critical(ext))
 878             return 0;
 879     }
 880
 881     return 1;
 882 }
 883
 884 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 885 {
 886     return 1;
 887 }
 888
 889 /*-
 890  * Various checks to see if one certificate potentially issued the second.
 891  * This can be used to prune a set of possible issuer certificates which
 892  * have been looked up using some simple method such as by subject name.
 893  * These are:
 894  * 1. Check issuer_name(subject) == subject_name(issuer)
 895  * 2. If akid(subject) exists, check that it matches issuer
 896  * 3. Check that issuer public key algorithm matches subject signature algorithm
 897  * 4. Check that any key_usage(issuer) allows certificate signing
 898  * Note that this does not include actually checking the signature.
 899  * Returns 0 for OK, or positive for reason for mismatch
 900  * where reason codes match those for X509_verify_cert().
 901  */
 902 int X509_check_issued(X509 *issuer, X509 *subject)
 903 {
 904     int ret;
 905
 906     if ((ret = x509_likely_issued(issuer, subject)) != X509_V_OK)
 907         return ret;
 908     return x509_signing_allowed(issuer, subject);
 909 }
 910
 911 /* do the checks 1., 2., and 3. as described above for X509_check_issued() */
 912 int x509_likely_issued(X509 *issuer, X509 *subject)
 913 {
 914     int ret;
 915
 916     if (X509_NAME_cmp(X509_get_subject_name(issuer),
 917                       X509_get_issuer_name(subject)) != 0)
 918         return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 919
 920     /* set issuer->skid and subject->akid */
 921     if (!x509v3_cache_extensions(issuer)
 922             || !x509v3_cache_extensions(subject))
 923         return X509_V_ERR_UNSPECIFIED;
 924
 925     ret = X509_check_akid(issuer, subject->akid);
 926     if (ret != X509_V_OK)
 927         return ret;
 928
 929     /* check if the subject signature alg matches the issuer's PUBKEY alg */
 930     return check_sig_alg_match(X509_get0_pubkey(issuer), subject);
 931 }
 932
 933 /*-
 934  * Check if certificate I<issuer> is allowed to issue certificate I<subject>
 935  * according to the B<keyUsage> field of I<issuer> if present
 936  * depending on any proxyCertInfo extension of I<subject>.
 937  * Returns 0 for OK, or positive for reason for rejection
 938  * where reason codes match those for X509_verify_cert().
 939  */
 940 int x509_signing_allowed(const X509 *issuer, const X509 *subject)
 941 {
 942     if (subject->ex_flags & EXFLAG_PROXY) {
 943         if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 944             return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 945     } else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
 946         return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 947     return X509_V_OK;
 948 }
 949
 950 int X509_check_akid(const X509 *issuer, const AUTHORITY_KEYID *akid)
 951 {
 952     if (akid == NULL)
 953         return X509_V_OK;
 954
 955     /* Check key ids (if present) */
 956     if (akid->keyid && issuer->skid &&
 957         ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid))
 958         return X509_V_ERR_AKID_SKID_MISMATCH;
 959     /* Check serial number */
 960     if (akid->serial &&
 961         ASN1_INTEGER_cmp(X509_get0_serialNumber(issuer), akid->serial))
 962         return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 963     /* Check issuer name */
 964     if (akid->issuer) {
 965         /*
 966          * Ugh, for some peculiar reason AKID includes SEQUENCE OF
 967          * GeneralName. So look for a DirName. There may be more than one but
 968          * we only take any notice of the first.
 969          */
 970         GENERAL_NAMES *gens;
 971         GENERAL_NAME *gen;
 972         X509_NAME *nm = NULL;
 973         int i;
 974         gens = akid->issuer;
 975         for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 976             gen = sk_GENERAL_NAME_value(gens, i);
 977             if (gen->type == GEN_DIRNAME) {
 978                 nm = gen->d.dirn;
 979                 break;
 980             }
 981         }
 982         if (nm != NULL && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)) != 0)
 983             return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 984     }
 985     return X509_V_OK;
 986 }
 987
 988 uint32_t X509_get_extension_flags(X509 *x)
 989 {
 990     /* Call for side-effect of computing hash and caching extensions */
 991     X509_check_purpose(x, -1, -1);
 992     return x->ex_flags;
 993 }
 994
 995 uint32_t X509_get_key_usage(X509 *x)
 996 {
 997     /* Call for side-effect of computing hash and caching extensions */
 998     if (X509_check_purpose(x, -1, -1) != 1)
 999         return 0;
1000     if (x->ex_flags & EXFLAG_KUSAGE)
1001         return x->ex_kusage;
1002     return UINT32_MAX;
1003 }
1004
1005 uint32_t X509_get_extended_key_usage(X509 *x)
1006 {
1007     /* Call for side-effect of computing hash and caching extensions */
1008     if (X509_check_purpose(x, -1, -1) != 1)
1009         return 0;
1010     if (x->ex_flags & EXFLAG_XKUSAGE)
1011         return x->ex_xkusage;
1012     return UINT32_MAX;
1013 }
1014
1015 const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x)
1016 {
1017     /* Call for side-effect of computing hash and caching extensions */
1018     if (X509_check_purpose(x, -1, -1) != 1)
1019         return NULL;
1020     return x->skid;
1021 }
1022
1023 const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x)
1024 {
1025     /* Call for side-effect of computing hash and caching extensions */
1026     if (X509_check_purpose(x, -1, -1) != 1)
1027         return NULL;
1028     return (x->akid != NULL ? x->akid->keyid : NULL);
1029 }
1030
1031 const GENERAL_NAMES *X509_get0_authority_issuer(X509 *x)
1032 {
1033     /* Call for side-effect of computing hash and caching extensions */
1034     if (X509_check_purpose(x, -1, -1) != 1)
1035         return NULL;
1036     return (x->akid != NULL ? x->akid->issuer : NULL);
1037 }
1038
1039 const ASN1_INTEGER *X509_get0_authority_serial(X509 *x)
1040 {
1041     /* Call for side-effect of computing hash and caching extensions */
1042     if (X509_check_purpose(x, -1, -1) != 1)
1043         return NULL;
1044     return (x->akid != NULL ? x->akid->serial : NULL);
1045 }
1046
1047 long X509_get_pathlen(X509 *x)
1048 {
1049     /* Called for side effect of caching extensions */
1050     if (X509_check_purpose(x, -1, -1) != 1
1051             || (x->ex_flags & EXFLAG_BCONS) == 0)
1052         return -1;
1053     return x->ex_pathlen;
1054 }
1055
1056 long X509_get_proxy_pathlen(X509 *x)
1057 {
1058     /* Called for side effect of caching extensions */
1059     if (X509_check_purpose(x, -1, -1) != 1
1060             || (x->ex_flags & EXFLAG_PROXY) == 0)
1061         return -1;
1062     return x->ex_pcpathlen;
1063 }