/src/libressl/crypto/x509/x509_purp.c

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/* $OpenBSD: x509_purp.c,v 1.16 2022/05/10 19:42:52 tb Exp $ */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project 2001.
 */
/* ====================================================================
 * Copyright (c) 1999-2004 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>
#include <string.h>

#include <openssl/opensslconf.h>

#include <openssl/err.h>
#include <openssl/x509v3.h>
#include <openssl/x509_vfy.h>

#include "x509_internal.h"
#include "x509_lcl.h"

#define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
#define ku_reject(x, usage) \
  (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
#define xku_reject(x, usage) \
  (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
#define ns_reject(x, usage) \
  (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))

void x509v3_cache_extensions(X509 *x);

static int check_ssl_ca(const X509 *x);
static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
    int ca);
static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
    int ca);
static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
    int ca);
static int purpose_smime(const X509 *x, int ca);
static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
    int ca);
static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
    int ca);
static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
    int ca);
static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
    int ca);
static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);

static int xp_cmp(const X509_PURPOSE * const *a, const X509_PURPOSE * const *b);
static void xptable_free(X509_PURPOSE *p);

static X509_PURPOSE xstandard[] = {
  {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0, check_purpose_ssl_client, "SSL client", "sslclient", NULL},
  {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ssl_server, "SSL server", "sslserver", NULL},
  {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
  {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign, "S/MIME signing", "smimesign", NULL},
  {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0, check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
  {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign, "CRL signing", "crlsign", NULL},
  {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any", NULL},
  {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper, "OCSP helper", "ocsphelper", NULL},
  {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0, check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign", NULL},
};

#define X509_PURPOSE_COUNT (sizeof(xstandard)/sizeof(X509_PURPOSE))

static STACK_OF(X509_PURPOSE) *xptable = NULL;

static int
xp_cmp(const X509_PURPOSE * const *a, const X509_PURPOSE * const *b)
{
  return (*a)->purpose - (*b)->purpose;
}

/* As much as I'd like to make X509_check_purpose use a "const" X509*
 * I really can't because it does recalculate hashes and do other non-const
 * things. */
int
X509_check_purpose(X509 *x, int id, int ca)
{
  int idx;
  const X509_PURPOSE *pt;

  if (!(x->ex_flags & EXFLAG_SET)) {
    CRYPTO_w_lock(CRYPTO_LOCK_X509);
    x509v3_cache_extensions(x);
    CRYPTO_w_unlock(CRYPTO_LOCK_X509);
    if (x->ex_flags & EXFLAG_INVALID)
      return -1;
  }
  if (id == -1)
    return 1;
  idx = X509_PURPOSE_get_by_id(id);
  if (idx == -1)
    return -1;
  pt = X509_PURPOSE_get0(idx);
  return pt->check_purpose(pt, x, ca);
}

int
X509_PURPOSE_set(int *p, int purpose)
{
  if (X509_PURPOSE_get_by_id(purpose) == -1) {
    X509V3error(X509V3_R_INVALID_PURPOSE);
    return 0;
  }
  *p = purpose;
  return 1;
}

int
X509_PURPOSE_get_count(void)
{
  if (!xptable)
    return X509_PURPOSE_COUNT;
  return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
}

X509_PURPOSE *
X509_PURPOSE_get0(int idx)
{
  if (idx < 0)
    return NULL;
  if (idx < (int)X509_PURPOSE_COUNT)
    return xstandard + idx;
  return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
}

int
X509_PURPOSE_get_by_sname(const char *sname)
{
  int i;
  X509_PURPOSE *xptmp;

  for (i = 0; i < X509_PURPOSE_get_count(); i++) {
    xptmp = X509_PURPOSE_get0(i);
    if (!strcmp(xptmp->sname, sname))
      return i;
  }
  return -1;
}

int
X509_PURPOSE_get_by_id(int purpose)
{
  X509_PURPOSE tmp;
  int idx;

  if ((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
    return purpose - X509_PURPOSE_MIN;
  tmp.purpose = purpose;
  if (!xptable)
    return -1;
  idx = sk_X509_PURPOSE_find(xptable, &tmp);
  if (idx == -1)
    return -1;
  return idx + X509_PURPOSE_COUNT;
}

int
X509_PURPOSE_add(int id, int trust, int flags,
    int (*ck)(const X509_PURPOSE *, const X509 *, int), const char *name,
    const char *sname, void *arg)
{
  int idx;
  X509_PURPOSE *ptmp;
  char *name_dup, *sname_dup;

  name_dup = sname_dup = NULL;

  if (name == NULL || sname == NULL) {
    X509V3error(X509V3_R_INVALID_NULL_ARGUMENT);
    return 0;
  }

  /* This is set according to what we change: application can't set it */
  flags &= ~X509_PURPOSE_DYNAMIC;
  /* This will always be set for application modified trust entries */
  flags |= X509_PURPOSE_DYNAMIC_NAME;
  /* Get existing entry if any */
  idx = X509_PURPOSE_get_by_id(id);
  /* Need a new entry */
  if (idx == -1) {
    if ((ptmp = malloc(sizeof(X509_PURPOSE))) == NULL) {
      X509V3error(ERR_R_MALLOC_FAILURE);
      return 0;
    }
    ptmp->flags = X509_PURPOSE_DYNAMIC;
  } else
    ptmp = X509_PURPOSE_get0(idx);

  if ((name_dup = strdup(name)) == NULL)
    goto err;
  if ((sname_dup = strdup(sname)) == NULL)
    goto err;

  /* free existing name if dynamic */
  if (ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
    free(ptmp->name);
    free(ptmp->sname);
  }
  /* dup supplied name */
  ptmp->name = name_dup;
  ptmp->sname = sname_dup;
  /* Keep the dynamic flag of existing entry */
  ptmp->flags &= X509_PURPOSE_DYNAMIC;
  /* Set all other flags */
  ptmp->flags |= flags;

  ptmp->purpose = id;
  ptmp->trust = trust;
  ptmp->check_purpose = ck;
  ptmp->usr_data = arg;

  /* If its a new entry manage the dynamic table */
  if (idx == -1) {
    if (xptable == NULL &&
        (xptable = sk_X509_PURPOSE_new(xp_cmp)) == NULL)
      goto err;
    if (sk_X509_PURPOSE_push(xptable, ptmp) == 0)
      goto err;
  }
  return 1;

err:
  free(name_dup);
  free(sname_dup);
  if (idx == -1)
    free(ptmp);
  X509V3error(ERR_R_MALLOC_FAILURE);
  return 0;
}

static void
xptable_free(X509_PURPOSE *p)
{
  if (!p)
    return;
  if (p->flags & X509_PURPOSE_DYNAMIC) {
    if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
      free(p->name);
      free(p->sname);
    }
    free(p);
  }
}

void
X509_PURPOSE_cleanup(void)
{
  sk_X509_PURPOSE_pop_free(xptable, xptable_free);
  xptable = NULL;
}

int
X509_PURPOSE_get_id(const X509_PURPOSE *xp)
{
  return xp->purpose;
}

char *
X509_PURPOSE_get0_name(const X509_PURPOSE *xp)
{
  return xp->name;
}

char *
X509_PURPOSE_get0_sname(const X509_PURPOSE *xp)
{
  return xp->sname;
}

int
X509_PURPOSE_get_trust(const X509_PURPOSE *xp)
{
  return xp->trust;
}

static int
nid_cmp(const int *a, const int *b)
{
  return *a - *b;
}

static int nid_cmp_BSEARCH_CMP_FN(const void *, const void *);
static int nid_cmp(int const *, int const *);
static int *OBJ_bsearch_nid(int *key, int const *base, int num);

static int
nid_cmp_BSEARCH_CMP_FN(const void *a_, const void *b_)
{
  int const *a = a_;
  int const *b = b_;
  return nid_cmp(a, b);
}

static int *
OBJ_bsearch_nid(int *key, int const *base, int num)
{
  return (int *)OBJ_bsearch_(key, base, num, sizeof(int),
      nid_cmp_BSEARCH_CMP_FN);
}

int
X509_supported_extension(X509_EXTENSION *ex)
{
  /* This table is a list of the NIDs of supported extensions:
   * that is those which are used by the verify process. If
   * an extension is critical and doesn't appear in this list
   * then the verify process will normally reject the certificate.
   * The list must be kept in numerical order because it will be
   * searched using bsearch.
   */

  static const int supported_nids[] = {
    NID_netscape_cert_type, /* 71 */
    NID_key_usage,   /* 83 */
    NID_subject_alt_name, /* 85 */
    NID_basic_constraints, /* 87 */
    NID_certificate_policies, /* 89 */
    NID_ext_key_usage, /* 126 */
#ifndef OPENSSL_NO_RFC3779
    NID_sbgp_ipAddrBlock,   /* 290 */
    NID_sbgp_autonomousSysNum, /* 291 */
#endif
    NID_policy_constraints, /* 401 */
    NID_proxyCertInfo, /* 663 */
    NID_name_constraints, /* 666 */
    NID_policy_mappings, /* 747 */
    NID_inhibit_any_policy  /* 748 */
  };

  int ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));

  if (ex_nid == NID_undef)
    return 0;

  if (OBJ_bsearch_nid(&ex_nid, supported_nids,
      sizeof(supported_nids) / sizeof(int)))
    return 1;
  return 0;
}

static void
setup_dp(X509 *x, DIST_POINT *dp)
{
  X509_NAME *iname = NULL;
  int i;

  if (dp->reasons) {
    if (dp->reasons->length > 0)
      dp->dp_reasons = dp->reasons->data[0];
    if (dp->reasons->length > 1)
      dp->dp_reasons |= (dp->reasons->data[1] << 8);
    dp->dp_reasons &= CRLDP_ALL_REASONS;
  } else
    dp->dp_reasons = CRLDP_ALL_REASONS;
  if (!dp->distpoint || (dp->distpoint->type != 1))
    return;
  for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
    GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
    if (gen->type == GEN_DIRNAME) {
      iname = gen->d.directoryName;
      break;
    }
  }
  if (!iname)
    iname = X509_get_issuer_name(x);

  DIST_POINT_set_dpname(dp->distpoint, iname);

}

static void
setup_crldp(X509 *x)
{
  int i;

  x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &i, NULL);
  if (x->crldp == NULL && i != -1) {
    x->ex_flags |= EXFLAG_INVALID;
    return;
  }

  for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++)
    setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
}

void
x509v3_cache_extensions(X509 *x)
{
  BASIC_CONSTRAINTS *bs;
  PROXY_CERT_INFO_EXTENSION *pci;
  ASN1_BIT_STRING *usage;
  ASN1_BIT_STRING *ns;
  EXTENDED_KEY_USAGE *extusage;
  X509_EXTENSION *ex;
  int i;

  if (x->ex_flags & EXFLAG_SET)
    return;

  X509_digest(x, X509_CERT_HASH_EVP, x->hash, NULL);

  /* V1 should mean no extensions ... */
  if (!X509_get_version(x))
    x->ex_flags |= EXFLAG_V1;

  /* Handle basic constraints */
  if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, &i, NULL))) {
    if (bs->ca)
      x->ex_flags |= EXFLAG_CA;
    if (bs->pathlen) {
      if ((bs->pathlen->type == V_ASN1_NEG_INTEGER) ||
          !bs->ca) {
        x->ex_flags |= EXFLAG_INVALID;
        x->ex_pathlen = 0;
      } else
        x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
    } else
      x->ex_pathlen = -1;
    BASIC_CONSTRAINTS_free(bs);
    x->ex_flags |= EXFLAG_BCONS;
  } else if (i != -1) {
    x->ex_flags |= EXFLAG_INVALID;
  }

  /* Handle proxy certificates */
  if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, &i, NULL))) {
    if (x->ex_flags & EXFLAG_CA ||
        X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0 ||
        X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
      x->ex_flags |= EXFLAG_INVALID;
    }
    if (pci->pcPathLengthConstraint) {
      if (pci->pcPathLengthConstraint->type ==
          V_ASN1_NEG_INTEGER) {
        x->ex_flags |= EXFLAG_INVALID;
        x->ex_pcpathlen = 0;
      } else
        x->ex_pcpathlen =
            ASN1_INTEGER_get(pci->
              pcPathLengthConstraint);
    } else
      x->ex_pcpathlen = -1;
    PROXY_CERT_INFO_EXTENSION_free(pci);
    x->ex_flags |= EXFLAG_PROXY;
  } else if (i != -1) {
    x->ex_flags |= EXFLAG_INVALID;
  }

  /* Handle key usage */
  if ((usage = X509_get_ext_d2i(x, NID_key_usage, &i, NULL))) {
    if (usage->length > 0) {
      x->ex_kusage = usage->data[0];
      if (usage->length > 1)
        x->ex_kusage |= usage->data[1] << 8;
    } else
      x->ex_kusage = 0;
    x->ex_flags |= EXFLAG_KUSAGE;
    ASN1_BIT_STRING_free(usage);
  } else if (i != -1) {
    x->ex_flags |= EXFLAG_INVALID;
  }

  x->ex_xkusage = 0;
  if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, &i, NULL))) {
    x->ex_flags |= EXFLAG_XKUSAGE;
    for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
      switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
      case NID_server_auth:
        x->ex_xkusage |= XKU_SSL_SERVER;
        break;

      case NID_client_auth:
        x->ex_xkusage |= XKU_SSL_CLIENT;
        break;

      case NID_email_protect:
        x->ex_xkusage |= XKU_SMIME;
        break;

      case NID_code_sign:
        x->ex_xkusage |= XKU_CODE_SIGN;
        break;

      case NID_ms_sgc:
      case NID_ns_sgc:
        x->ex_xkusage |= XKU_SGC;
        break;

      case NID_OCSP_sign:
        x->ex_xkusage |= XKU_OCSP_SIGN;
        break;

      case NID_time_stamp:
        x->ex_xkusage |= XKU_TIMESTAMP;
        break;

      case NID_dvcs:
        x->ex_xkusage |= XKU_DVCS;
        break;

      case NID_anyExtendedKeyUsage:
        x->ex_xkusage |= XKU_ANYEKU;
        break;
      }
    }
    sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
  } else if (i != -1) {
    x->ex_flags |= EXFLAG_INVALID;
  }

  if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, &i, NULL))) {
    if (ns->length > 0)
      x->ex_nscert = ns->data[0];
    else
      x->ex_nscert = 0;
    x->ex_flags |= EXFLAG_NSCERT;
    ASN1_BIT_STRING_free(ns);
  } else if (i != -1) {
    x->ex_flags |= EXFLAG_INVALID;
  }

  x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, &i, NULL);
  if (x->skid == NULL && i != -1)
    x->ex_flags |= EXFLAG_INVALID;
  x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, &i, NULL);
  if (x->akid == NULL && i != -1)
    x->ex_flags |= EXFLAG_INVALID;

  /* Does subject name match issuer? */
  if (!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x))) {
    x->ex_flags |= EXFLAG_SI;
    /* If SKID matches AKID also indicate self signed. */
    if (X509_check_akid(x, x->akid) == X509_V_OK &&
        !ku_reject(x, KU_KEY_CERT_SIGN))
      x->ex_flags |= EXFLAG_SS;
  }

  x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, &i, NULL);
  if (x->altname == NULL && i != -1)
    x->ex_flags |= EXFLAG_INVALID;
  x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
  if (!x->nc && (i != -1))
    x->ex_flags |= EXFLAG_INVALID;
  setup_crldp(x);

#ifndef OPENSSL_NO_RFC3779
  x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, &i, NULL);
  if (x->rfc3779_addr == NULL && i != -1)
    x->ex_flags |= EXFLAG_INVALID;
  if (!X509v3_addr_is_canonical(x->rfc3779_addr))
    x->ex_flags |= EXFLAG_INVALID;
  x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum, &i, NULL);
  if (x->rfc3779_asid == NULL && i != -1)
    x->ex_flags |= EXFLAG_INVALID;
  if (!X509v3_asid_is_canonical(x->rfc3779_asid))
    x->ex_flags |= EXFLAG_INVALID;
#endif

  for (i = 0; i < X509_get_ext_count(x); i++) {
    ex = X509_get_ext(x, i);
    if (OBJ_obj2nid(X509_EXTENSION_get_object(ex)) ==
        NID_freshest_crl)
      x->ex_flags |= EXFLAG_FRESHEST;
    if (!X509_EXTENSION_get_critical(ex))
      continue;
    if (!X509_supported_extension(ex)) {
      x->ex_flags |= EXFLAG_CRITICAL;
      break;
    }
  }

  x509_verify_cert_info_populate(x);

  x->ex_flags |= EXFLAG_SET;
}

/* CA checks common to all purposes
 * return codes:
 * 0 not a CA
 * 1 is a CA
 * 2 basicConstraints absent so "maybe" a CA
 * 3 basicConstraints absent but self signed V1.
 * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 */

static int
check_ca(const X509 *x)
{
  /* keyUsage if present should allow cert signing */
  if (ku_reject(x, KU_KEY_CERT_SIGN))
    return 0;
  if (x->ex_flags & EXFLAG_BCONS) {
    if (x->ex_flags & EXFLAG_CA)
      return 1;
    /* If basicConstraints says not a CA then say so */
    else
      return 0;
  } else {
    /* we support V1 roots for...  uh, I don't really know why. */
    if ((x->ex_flags & V1_ROOT) == V1_ROOT)
      return 3;
    /* If key usage present it must have certSign so tolerate it */
    else if (x->ex_flags & EXFLAG_KUSAGE)
      return 4;
    /* Older certificates could have Netscape-specific CA types */
    else if (x->ex_flags & EXFLAG_NSCERT &&
        x->ex_nscert & NS_ANY_CA)
      return 5;
    /* can this still be regarded a CA certificate?  I doubt it */
    return 0;
  }
}

int
X509_check_ca(X509 *x)
{
  if (!(x->ex_flags & EXFLAG_SET)) {
    CRYPTO_w_lock(CRYPTO_LOCK_X509);
    x509v3_cache_extensions(x);
    CRYPTO_w_unlock(CRYPTO_LOCK_X509);
  }

  return check_ca(x);
}

/* Check SSL CA: common checks for SSL client and server */
static int
check_ssl_ca(const X509 *x)
{
  int ca_ret;

  ca_ret = check_ca(x);
  if (!ca_ret)
    return 0;
  /* check nsCertType if present */
  if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
    return ca_ret;
  else
    return 0;
}

static int
check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
{
  if (xku_reject(x, XKU_SSL_CLIENT))
    return 0;
  if (ca)
    return check_ssl_ca(x);
  /* We need to do digital signatures with it */
  if (ku_reject(x, KU_DIGITAL_SIGNATURE))
    return 0;
  /* nsCertType if present should allow SSL client use */
  if (ns_reject(x, NS_SSL_CLIENT))
    return 0;
  return 1;
}

static int
check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
{
  if (xku_reject(x, XKU_SSL_SERVER|XKU_SGC))
    return 0;
  if (ca)
    return check_ssl_ca(x);

  if (ns_reject(x, NS_SSL_SERVER))
    return 0;
  /* Now as for keyUsage: we'll at least need to sign OR encipher */
  if (ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT))
    return 0;

  return 1;
}

static int
check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
{
  int ret;

  ret = check_purpose_ssl_server(xp, x, ca);
  if (!ret || ca)
    return ret;
  /* We need to encipher or Netscape complains */
  if (ku_reject(x, KU_KEY_ENCIPHERMENT))
    return 0;
  return ret;
}

/* common S/MIME checks */
static int
purpose_smime(const X509 *x, int ca)
{
  if (xku_reject(x, XKU_SMIME))
    return 0;
  if (ca) {
    int ca_ret;
    ca_ret = check_ca(x);
    if (!ca_ret)
      return 0;
    /* check nsCertType if present */
    if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
      return ca_ret;
    else
      return 0;
  }
  if (x->ex_flags & EXFLAG_NSCERT) {
    if (x->ex_nscert & NS_SMIME)
      return 1;
    /* Workaround for some buggy certificates */
    if (x->ex_nscert & NS_SSL_CLIENT)
      return 2;
    return 0;
  }
  return 1;
}

static int
check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
{
  int ret;

  ret = purpose_smime(x, ca);
  if (!ret || ca)
    return ret;
  if (ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION))
    return 0;
  return ret;
}

static int
check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
{
  int ret;

  ret = purpose_smime(x, ca);
  if (!ret || ca)
    return ret;
  if (ku_reject(x, KU_KEY_ENCIPHERMENT))
    return 0;
  return ret;
}

static int
check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
{
  if (ca) {
    int ca_ret;
    if ((ca_ret = check_ca(x)) != 2)
      return ca_ret;
    else
      return 0;
  }
  if (ku_reject(x, KU_CRL_SIGN))
    return 0;
  return 1;
}

/* OCSP helper: this is *not* a full OCSP check. It just checks that
 * each CA is valid. Additional checks must be made on the chain.
 */
static int
ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
{
  /* Must be a valid CA.  Should we really support the "I don't know"
     value (2)? */
  if (ca)
    return check_ca(x);
  /* leaf certificate is checked in OCSP_verify() */
  return 1;
}

static int
check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
{
  int i_ext;

  /* If ca is true we must return if this is a valid CA certificate. */
  if (ca)
    return check_ca(x);

  /*
   * Check the optional key usage field:
   * if Key Usage is present, it must be one of digitalSignature
   * and/or nonRepudiation (other values are not consistent and shall
   * be rejected).
   */
  if ((x->ex_flags & EXFLAG_KUSAGE) &&
      ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
      !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
    return 0;

  /* Only time stamp key usage is permitted and it's required. */
  if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
    return 0;

  /* Extended Key Usage MUST be critical */
  i_ext = X509_get_ext_by_NID((X509 *) x, NID_ext_key_usage, -1);
  if (i_ext >= 0) {
    X509_EXTENSION *ext = X509_get_ext((X509 *) x, i_ext);
    if (!X509_EXTENSION_get_critical(ext))
      return 0;
  }

  return 1;
}

static int
no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
{
  return 1;
}

/* Various checks to see if one certificate issued the second.
 * This can be used to prune a set of possible issuer certificates
 * which have been looked up using some simple method such as by
 * subject name.
 * These are:
 * 1. Check issuer_name(subject) == subject_name(issuer)
 * 2. If akid(subject) exists check it matches issuer
 * 3. If key_usage(issuer) exists check it supports certificate signing
 * returns 0 for OK, positive for reason for mismatch, reasons match
 * codes for X509_verify_cert()
 */

int
X509_check_issued(X509 *issuer, X509 *subject)
{
  if (X509_NAME_cmp(X509_get_subject_name(issuer),
      X509_get_issuer_name(subject)))
    return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
  if (!(issuer->ex_flags & EXFLAG_SET)) {
    CRYPTO_w_lock(CRYPTO_LOCK_X509);
    x509v3_cache_extensions(issuer);
    CRYPTO_w_unlock(CRYPTO_LOCK_X509);
  }
  if (issuer->ex_flags & EXFLAG_INVALID)
    return X509_V_ERR_UNSPECIFIED;
  if (!(subject->ex_flags & EXFLAG_SET)) {
    CRYPTO_w_lock(CRYPTO_LOCK_X509);
    x509v3_cache_extensions(subject);
    CRYPTO_w_unlock(CRYPTO_LOCK_X509);
  }
  if (subject->ex_flags & EXFLAG_INVALID)
    return X509_V_ERR_UNSPECIFIED;

  if (subject->akid) {
    int ret = X509_check_akid(issuer, subject->akid);
    if (ret != X509_V_OK)
      return ret;
  }

  if (subject->ex_flags & EXFLAG_PROXY) {
    if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
      return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
  } else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
    return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
  return X509_V_OK;
}

int
X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
{
  if (!akid)
    return X509_V_OK;

  /* Check key ids (if present) */
  if (akid->keyid && issuer->skid &&
      ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid) )
    return X509_V_ERR_AKID_SKID_MISMATCH;
  /* Check serial number */
  if (akid->serial &&
      ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
    return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
  /* Check issuer name */
  if (akid->issuer) {
    /* Ugh, for some peculiar reason AKID includes
     * SEQUENCE OF GeneralName. So look for a DirName.
     * There may be more than one but we only take any
     * notice of the first.
     */
    GENERAL_NAMES *gens;
    GENERAL_NAME *gen;
    X509_NAME *nm = NULL;
    int i;
    gens = akid->issuer;
    for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
      gen = sk_GENERAL_NAME_value(gens, i);
      if (gen->type == GEN_DIRNAME) {
        nm = gen->d.dirn;
        break;
      }
    }
    if (nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
      return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
  }
  return X509_V_OK;
}

uint32_t
X509_get_extension_flags(X509 *x)
{
  /* Call for side-effect of computing hash and caching extensions */
  if (X509_check_purpose(x, -1, -1) != 1)
    return EXFLAG_INVALID;

  return x->ex_flags;
}

uint32_t
X509_get_key_usage(X509 *x)
{
  /* Call for side-effect of computing hash and caching extensions */
  if (X509_check_purpose(x, -1, -1) != 1)
    return 0;

  if (x->ex_flags & EXFLAG_KUSAGE)
    return x->ex_kusage;

  return UINT32_MAX;
}

uint32_t
X509_get_extended_key_usage(X509 *x)
{
  /* Call for side-effect of computing hash and caching extensions */
  if (X509_check_purpose(x, -1, -1) != 1)
    return 0;

  if (x->ex_flags & EXFLAG_XKUSAGE)
    return x->ex_xkusage;

  return UINT32_MAX;
}

Coverage Report

Created: 2022-08-24 06:31