crypto/x509v3/v3_purp.c

   1 /*
   2  * Copyright 1999-2018 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 "internal/x509_int.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
  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 || !ptmp->sname) {
 182         X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 183         goto err;
 184     }
 185     /* Keep the dynamic flag of existing entry */
 186     ptmp->flags &= X509_PURPOSE_DYNAMIC;
 187     /* Set all other flags */
 188     ptmp->flags |= flags;
 189
 190     ptmp->purpose = id;
 191     ptmp->trust = trust;
 192     ptmp->check_purpose = ck;
 193     ptmp->usr_data = arg;
 194
 195     /* If its a new entry manage the dynamic table */
 196     if (idx == -1) {
 197         if (xptable == NULL
 198             && (xptable = sk_X509_PURPOSE_new(xp_cmp)) == NULL) {
 199             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 200             goto err;
 201         }
 202         if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
 203             X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
 204             goto err;
 205         }
 206     }
 207     return 1;
 208  err:
 209     if (idx == -1) {
 210         OPENSSL_free(ptmp->name);
 211         OPENSSL_free(ptmp->sname);
 212         OPENSSL_free(ptmp);
 213     }
 214     return 0;
 215 }
 216
 217 static void xptable_free(X509_PURPOSE *p)
 218 {
 219     if (!p)
 220         return;
 221     if (p->flags & X509_PURPOSE_DYNAMIC) {
 222         if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
 223             OPENSSL_free(p->name);
 224             OPENSSL_free(p->sname);
 225         }
 226         OPENSSL_free(p);
 227     }
 228 }
 229
 230 void X509_PURPOSE_cleanup(void)
 231 {
 232     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 static void setup_dp(X509 *x, DIST_POINT *dp)
 304 {
 305     X509_NAME *iname = NULL;
 306     int i;
 307     if (dp->reasons) {
 308         if (dp->reasons->length > 0)
 309             dp->dp_reasons = dp->reasons->data[0];
 310         if (dp->reasons->length > 1)
 311             dp->dp_reasons |= (dp->reasons->data[1] << 8);
 312         dp->dp_reasons &= CRLDP_ALL_REASONS;
 313     } else
 314         dp->dp_reasons = CRLDP_ALL_REASONS;
 315     if (!dp->distpoint || (dp->distpoint->type != 1))
 316         return;
 317     for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
 318         GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
 319         if (gen->type == GEN_DIRNAME) {
 320             iname = gen->d.directoryName;
 321             break;
 322         }
 323     }
 324     if (!iname)
 325         iname = X509_get_issuer_name(x);
 326
 327     DIST_POINT_set_dpname(dp->distpoint, iname);
 328
 329 }
 330
 331 static void setup_crldp(X509 *x)
 332 {
 333     int i;
 334     x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL);
 335     for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++)
 336         setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
 337 }
 338
 339 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
 340 #define ku_reject(x, usage) \
 341         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
 342 #define xku_reject(x, usage) \
 343         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
 344 #define ns_reject(x, usage) \
 345         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 346
 347 static void x509v3_cache_extensions(X509 *x)
 348 {
 349     BASIC_CONSTRAINTS *bs;
 350     PROXY_CERT_INFO_EXTENSION *pci;
 351     ASN1_BIT_STRING *usage;
 352     ASN1_BIT_STRING *ns;
 353     EXTENDED_KEY_USAGE *extusage;
 354     X509_EXTENSION *ex;
 355     int i;
 356
 357 #ifdef tsan_ld_acq
 358     /* fast lock-free check, see end of the function for details. */
 359     if (tsan_ld_acq((TSAN_QUALIFIER int *)&x->ex_cached))
 360         return;
 361 #endif
 362
 363     CRYPTO_THREAD_write_lock(x->lock);
 364     if (x->ex_flags & EXFLAG_SET) {
 365         CRYPTO_THREAD_unlock(x->lock);
 366         return;
 367     }
 368
 369     X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
 370     /* V1 should mean no extensions ... */
 371     if (!X509_get_version(x))
 372         x->ex_flags |= EXFLAG_V1;
 373     /* Handle basic constraints */
 374     if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
 375         if (bs->ca)
 376             x->ex_flags |= EXFLAG_CA;
 377         if (bs->pathlen) {
 378             if ((bs->pathlen->type == V_ASN1_NEG_INTEGER)
 379                 || !bs->ca) {
 380                 x->ex_flags |= EXFLAG_INVALID;
 381                 x->ex_pathlen = 0;
 382             } else
 383                 x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
 384         } else
 385             x->ex_pathlen = -1;
 386         BASIC_CONSTRAINTS_free(bs);
 387         x->ex_flags |= EXFLAG_BCONS;
 388     }
 389     /* Handle proxy certificates */
 390     if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
 391         if (x->ex_flags & EXFLAG_CA
 392             || X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
 393             || X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
 394             x->ex_flags |= EXFLAG_INVALID;
 395         }
 396         if (pci->pcPathLengthConstraint) {
 397             x->ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
 398         } else
 399             x->ex_pcpathlen = -1;
 400         PROXY_CERT_INFO_EXTENSION_free(pci);
 401         x->ex_flags |= EXFLAG_PROXY;
 402     }
 403     /* Handle key usage */
 404     if ((usage = X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
 405         if (usage->length > 0) {
 406             x->ex_kusage = usage->data[0];
 407             if (usage->length > 1)
 408                 x->ex_kusage |= usage->data[1] << 8;
 409         } else
 410             x->ex_kusage = 0;
 411         x->ex_flags |= EXFLAG_KUSAGE;
 412         ASN1_BIT_STRING_free(usage);
 413     }
 414     x->ex_xkusage = 0;
 415     if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
 416         x->ex_flags |= EXFLAG_XKUSAGE;
 417         for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
 418             switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
 419             case NID_server_auth:
 420                 x->ex_xkusage |= XKU_SSL_SERVER;
 421                 break;
 422
 423             case NID_client_auth:
 424                 x->ex_xkusage |= XKU_SSL_CLIENT;
 425                 break;
 426
 427             case NID_email_protect:
 428                 x->ex_xkusage |= XKU_SMIME;
 429                 break;
 430
 431             case NID_code_sign:
 432                 x->ex_xkusage |= XKU_CODE_SIGN;
 433                 break;
 434
 435             case NID_ms_sgc:
 436             case NID_ns_sgc:
 437                 x->ex_xkusage |= XKU_SGC;
 438                 break;
 439
 440             case NID_OCSP_sign:
 441                 x->ex_xkusage |= XKU_OCSP_SIGN;
 442                 break;
 443
 444             case NID_time_stamp:
 445                 x->ex_xkusage |= XKU_TIMESTAMP;
 446                 break;
 447
 448             case NID_dvcs:
 449                 x->ex_xkusage |= XKU_DVCS;
 450                 break;
 451
 452             case NID_anyExtendedKeyUsage:
 453                 x->ex_xkusage |= XKU_ANYEKU;
 454                 break;
 455             }
 456         }
 457         sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
 458     }
 459
 460     if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
 461         if (ns->length > 0)
 462             x->ex_nscert = ns->data[0];
 463         else
 464             x->ex_nscert = 0;
 465         x->ex_flags |= EXFLAG_NSCERT;
 466         ASN1_BIT_STRING_free(ns);
 467     }
 468     x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
 469     x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
 470     /* Does subject name match issuer ? */
 471     if (!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x))) {
 472         x->ex_flags |= EXFLAG_SI;
 473         /* If SKID matches AKID also indicate self signed */
 474         if (X509_check_akid(x, x->akid) == X509_V_OK &&
 475             !ku_reject(x, KU_KEY_CERT_SIGN))
 476             x->ex_flags |= EXFLAG_SS;
 477     }
 478     x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
 479     x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
 480     if (!x->nc && (i != -1))
 481         x->ex_flags |= EXFLAG_INVALID;
 482     setup_crldp(x);
 483
 484 #ifndef OPENSSL_NO_RFC3779
 485     x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
 486     x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
 487                                        NULL, NULL);
 488 #endif
 489     for (i = 0; i < X509_get_ext_count(x); i++) {
 490         ex = X509_get_ext(x, i);
 491         if (OBJ_obj2nid(X509_EXTENSION_get_object(ex))
 492             == NID_freshest_crl)
 493             x->ex_flags |= EXFLAG_FRESHEST;
 494         if (!X509_EXTENSION_get_critical(ex))
 495             continue;
 496         if (!X509_supported_extension(ex)) {
 497             x->ex_flags |= EXFLAG_CRITICAL;
 498             break;
 499         }
 500     }
 501     x509_init_sig_info(x);
 502     x->ex_flags |= EXFLAG_SET;
 503 #ifdef tsan_st_rel
 504     tsan_st_rel((TSAN_QUALIFIER int *)&x->ex_cached, 1);
 505     /*
 506      * Above store triggers fast lock-free check in the beginning of the
 507      * function. But one has to ensure that the structure is "stable", i.e.
 508      * all stores are visible on all processors. Hence the release fence.
 509      */
 510 #endif
 511     CRYPTO_THREAD_unlock(x->lock);
 512 }
 513
 514 /*-
 515  * CA checks common to all purposes
 516  * return codes:
 517  * 0 not a CA
 518  * 1 is a CA
 519  * 2 basicConstraints absent so "maybe" a CA
 520  * 3 basicConstraints absent but self signed V1.
 521  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 522  */
 523
 524 static int check_ca(const X509 *x)
 525 {
 526     /* keyUsage if present should allow cert signing */
 527     if (ku_reject(x, KU_KEY_CERT_SIGN))
 528         return 0;
 529     if (x->ex_flags & EXFLAG_BCONS) {
 530         if (x->ex_flags & EXFLAG_CA)
 531             return 1;
 532         /* If basicConstraints says not a CA then say so */
 533         else
 534             return 0;
 535     } else {
 536         /* we support V1 roots for...  uh, I don't really know why. */
 537         if ((x->ex_flags & V1_ROOT) == V1_ROOT)
 538             return 3;
 539         /*
 540          * If key usage present it must have certSign so tolerate it
 541          */
 542         else if (x->ex_flags & EXFLAG_KUSAGE)
 543             return 4;
 544         /* Older certificates could have Netscape-specific CA types */
 545         else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
 546             return 5;
 547         /* can this still be regarded a CA certificate?  I doubt it */
 548         return 0;
 549     }
 550 }
 551
 552 void X509_set_proxy_flag(X509 *x)
 553 {
 554     x->ex_flags |= EXFLAG_PROXY;
 555 }
 556
 557 void X509_set_proxy_pathlen(X509 *x, long l)
 558 {
 559     x->ex_pcpathlen = l;
 560 }
 561
 562 int X509_check_ca(X509 *x)
 563 {
 564     x509v3_cache_extensions(x);
 565
 566     return check_ca(x);
 567 }
 568
 569 /* Check SSL CA: common checks for SSL client and server */
 570 static int check_ssl_ca(const X509 *x)
 571 {
 572     int ca_ret;
 573     ca_ret = check_ca(x);
 574     if (!ca_ret)
 575         return 0;
 576     /* check nsCertType if present */
 577     if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
 578         return ca_ret;
 579     else
 580         return 0;
 581 }
 582
 583 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
 584                                     int ca)
 585 {
 586     if (xku_reject(x, XKU_SSL_CLIENT))
 587         return 0;
 588     if (ca)
 589         return check_ssl_ca(x);
 590     /* We need to do digital signatures or key agreement */
 591     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
 592         return 0;
 593     /* nsCertType if present should allow SSL client use */
 594     if (ns_reject(x, NS_SSL_CLIENT))
 595         return 0;
 596     return 1;
 597 }
 598
 599 /*
 600  * Key usage needed for TLS/SSL server: digital signature, encipherment or
 601  * key agreement. The ssl code can check this more thoroughly for individual
 602  * key types.
 603  */
 604 #define KU_TLS \
 605         KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT
 606
 607 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 608                                     int ca)
 609 {
 610     if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
 611         return 0;
 612     if (ca)
 613         return check_ssl_ca(x);
 614
 615     if (ns_reject(x, NS_SSL_SERVER))
 616         return 0;
 617     if (ku_reject(x, KU_TLS))
 618         return 0;
 619
 620     return 1;
 621
 622 }
 623
 624 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
 625                                        int ca)
 626 {
 627     int ret;
 628     ret = check_purpose_ssl_server(xp, x, ca);
 629     if (!ret || ca)
 630         return ret;
 631     /* We need to encipher or Netscape complains */
 632     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 633         return 0;
 634     return ret;
 635 }
 636
 637 /* common S/MIME checks */
 638 static int purpose_smime(const X509 *x, int ca)
 639 {
 640     if (xku_reject(x, XKU_SMIME))
 641         return 0;
 642     if (ca) {
 643         int ca_ret;
 644         ca_ret = check_ca(x);
 645         if (!ca_ret)
 646             return 0;
 647         /* check nsCertType if present */
 648         if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
 649             return ca_ret;
 650         else
 651             return 0;
 652     }
 653     if (x->ex_flags & EXFLAG_NSCERT) {
 654         if (x->ex_nscert & NS_SMIME)
 655             return 1;
 656         /* Workaround for some buggy certificates */
 657         if (x->ex_nscert & NS_SSL_CLIENT)
 658             return 2;
 659         return 0;
 660     }
 661     return 1;
 662 }
 663
 664 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
 665                                     int ca)
 666 {
 667     int ret;
 668     ret = purpose_smime(x, ca);
 669     if (!ret || ca)
 670         return ret;
 671     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION))
 672         return 0;
 673     return ret;
 674 }
 675
 676 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
 677                                        int ca)
 678 {
 679     int ret;
 680     ret = purpose_smime(x, ca);
 681     if (!ret || ca)
 682         return ret;
 683     if (ku_reject(x, KU_KEY_ENCIPHERMENT))
 684         return 0;
 685     return ret;
 686 }
 687
 688 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
 689                                   int ca)
 690 {
 691     if (ca) {
 692         int ca_ret;
 693         if ((ca_ret = check_ca(x)) != 2)
 694             return ca_ret;
 695         else
 696             return 0;
 697     }
 698     if (ku_reject(x, KU_CRL_SIGN))
 699         return 0;
 700     return 1;
 701 }
 702
 703 /*
 704  * OCSP helper: this is *not* a full OCSP check. It just checks that each CA
 705  * is valid. Additional checks must be made on the chain.
 706  */
 707
 708 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 709 {
 710     /*
 711      * Must be a valid CA.  Should we really support the "I don't know" value
 712      * (2)?
 713      */
 714     if (ca)
 715         return check_ca(x);
 716     /* leaf certificate is checked in OCSP_verify() */
 717     return 1;
 718 }
 719
 720 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
 721                                         int ca)
 722 {
 723     int i_ext;
 724
 725     /* If ca is true we must return if this is a valid CA certificate. */
 726     if (ca)
 727         return check_ca(x);
 728
 729     /*
 730      * Check the optional key usage field:
 731      * if Key Usage is present, it must be one of digitalSignature
 732      * and/or nonRepudiation (other values are not consistent and shall
 733      * be rejected).
 734      */
 735     if ((x->ex_flags & EXFLAG_KUSAGE)
 736         && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
 737             !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
 738         return 0;
 739
 740     /* Only time stamp key usage is permitted and it's required. */
 741     if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
 742         return 0;
 743
 744     /* Extended Key Usage MUST be critical */
 745     i_ext = X509_get_ext_by_NID(x, NID_ext_key_usage, -1);
 746     if (i_ext >= 0) {
 747         X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
 748         if (!X509_EXTENSION_get_critical(ext))
 749             return 0;
 750     }
 751
 752     return 1;
 753 }
 754
 755 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
 756 {
 757     return 1;
 758 }
 759
 760 /*-
 761  * Various checks to see if one certificate issued the second.
 762  * This can be used to prune a set of possible issuer certificates
 763  * which have been looked up using some simple method such as by
 764  * subject name.
 765  * These are:
 766  * 1. Check issuer_name(subject) == subject_name(issuer)
 767  * 2. If akid(subject) exists, check that it matches issuer
 768  * 3. Check that issuer public key algorithm matches subject signature algorithm
 769  * 4. If key_usage(issuer) exists, check that it supports certificate signing
 770  * returns 0 for OK, positive for reason for mismatch, reasons match
 771  * codes for X509_verify_cert()
 772  */
 773
 774 int X509_check_issued(X509 *issuer, X509 *subject)
 775 {
 776     if (X509_NAME_cmp(X509_get_subject_name(issuer),
 777                       X509_get_issuer_name(subject)))
 778         return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
 779
 780     x509v3_cache_extensions(issuer);
 781     x509v3_cache_extensions(subject);
 782
 783     if (subject->akid) {
 784         int ret = X509_check_akid(issuer, subject->akid);
 785         if (ret != X509_V_OK)
 786             return ret;
 787     }
 788
 789     {
 790         /*
 791          * Check if the subject signature algorithm matches the issuer's PUBKEY
 792          * algorithm
 793          */
 794         EVP_PKEY *i_pkey = X509_get0_pubkey(issuer);
 795         X509_ALGOR *s_algor = &subject->cert_info.signature;
 796         int s_pknid = NID_undef, s_mdnid = NID_undef;
 797
 798         if (i_pkey == NULL)
 799             return X509_V_ERR_NO_ISSUER_PUBLIC_KEY;
 800
 801         if (!OBJ_find_sigid_algs(OBJ_obj2nid(s_algor->algorithm),
 802                                  &s_mdnid, &s_pknid)
 803             || EVP_PKEY_type(s_pknid) != EVP_PKEY_base_id(i_pkey))
 804             return X509_V_ERR_SIGNATURE_ALGORITHM_MISMATCH;
 805     }
 806
 807     if (subject->ex_flags & EXFLAG_PROXY) {
 808         if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
 809             return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
 810     } else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
 811         return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
 812     return X509_V_OK;
 813 }
 814
 815 int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
 816 {
 817
 818     if (!akid)
 819         return X509_V_OK;
 820
 821     /* Check key ids (if present) */
 822     if (akid->keyid && issuer->skid &&
 823         ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid))
 824         return X509_V_ERR_AKID_SKID_MISMATCH;
 825     /* Check serial number */
 826     if (akid->serial &&
 827         ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
 828         return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 829     /* Check issuer name */
 830     if (akid->issuer) {
 831         /*
 832          * Ugh, for some peculiar reason AKID includes SEQUENCE OF
 833          * GeneralName. So look for a DirName. There may be more than one but
 834          * we only take any notice of the first.
 835          */
 836         GENERAL_NAMES *gens;
 837         GENERAL_NAME *gen;
 838         X509_NAME *nm = NULL;
 839         int i;
 840         gens = akid->issuer;
 841         for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
 842             gen = sk_GENERAL_NAME_value(gens, i);
 843             if (gen->type == GEN_DIRNAME) {
 844                 nm = gen->d.dirn;
 845                 break;
 846             }
 847         }
 848         if (nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
 849             return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
 850     }
 851     return X509_V_OK;
 852 }
 853
 854 uint32_t X509_get_extension_flags(X509 *x)
 855 {
 856     /* Call for side-effect of computing hash and caching extensions */
 857     X509_check_purpose(x, -1, -1);
 858     return x->ex_flags;
 859 }
 860
 861 uint32_t X509_get_key_usage(X509 *x)
 862 {
 863     /* Call for side-effect of computing hash and caching extensions */
 864     X509_check_purpose(x, -1, -1);
 865     if (x->ex_flags & EXFLAG_KUSAGE)
 866         return x->ex_kusage;
 867     return UINT32_MAX;
 868 }
 869
 870 uint32_t X509_get_extended_key_usage(X509 *x)
 871 {
 872     /* Call for side-effect of computing hash and caching extensions */
 873     X509_check_purpose(x, -1, -1);
 874     if (x->ex_flags & EXFLAG_XKUSAGE)
 875         return x->ex_xkusage;
 876     return UINT32_MAX;
 877 }
 878
 879 const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x)
 880 {
 881     /* Call for side-effect of computing hash and caching extensions */
 882     X509_check_purpose(x, -1, -1);
 883     return x->skid;
 884 }
 885
 886 const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x)
 887 {
 888     /* Call for side-effect of computing hash and caching extensions */
 889     X509_check_purpose(x, -1, -1);
 890     return (x->akid != NULL ? x->akid->keyid : NULL);
 891 }
 892
 893 long X509_get_pathlen(X509 *x)
 894 {
 895     /* Called for side effect of caching extensions */
 896     if (X509_check_purpose(x, -1, -1) != 1
 897             || (x->ex_flags & EXFLAG_BCONS) == 0)
 898         return -1;
 899     return x->ex_pathlen;
 900 }
 901
 902 long X509_get_proxy_pathlen(X509 *x)
 903 {
 904     /* Called for side effect of caching extensions */
 905     if (X509_check_purpose(x, -1, -1) != 1
 906             || (x->ex_flags & EXFLAG_PROXY) == 0)
 907         return -1;
 908     return x->ex_pcpathlen;
 909 }