/src/libressl/crypto/x509/x509_vfy.c

Source (jump to first uncovered line)
/* $OpenBSD: x509_vfy.c,v 1.102 2022/06/27 14:10:22 tb Exp $ */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * 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 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 acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS 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 AUTHOR OR 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.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <openssl/opensslconf.h>

#include <openssl/asn1.h>
#include <openssl/buffer.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/lhash.h>
#include <openssl/objects.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include "asn1_locl.h"
#include "vpm_int.h"
#include "x509_internal.h"

/* CRL score values */

/* No unhandled critical extensions */

#define CRL_SCORE_NOCRITICAL  0x100

/* certificate is within CRL scope */

#define CRL_SCORE_SCOPE   0x080

/* CRL times valid */

#define CRL_SCORE_TIME    0x040

/* Issuer name matches certificate */

#define CRL_SCORE_ISSUER_NAME 0x020

/* If this score or above CRL is probably valid */

#define CRL_SCORE_VALID (CRL_SCORE_NOCRITICAL|CRL_SCORE_TIME|CRL_SCORE_SCOPE)

/* CRL issuer is certificate issuer */

#define CRL_SCORE_ISSUER_CERT 0x018

/* CRL issuer is on certificate path */

#define CRL_SCORE_SAME_PATH 0x008

/* CRL issuer matches CRL AKID */

#define CRL_SCORE_AKID    0x004

/* Have a delta CRL with valid times */

#define CRL_SCORE_TIME_DELTA  0x002

static int null_callback(int ok, X509_STORE_CTX *e);
static int check_issued(X509_STORE_CTX *ctx, X509 *x, X509 *issuer);
static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x,
    int allow_expired);
static int check_chain_extensions(X509_STORE_CTX *ctx);
static int check_name_constraints(X509_STORE_CTX *ctx);
static int check_trust(X509_STORE_CTX *ctx);
static int check_revocation(X509_STORE_CTX *ctx);
static int check_cert(X509_STORE_CTX *ctx, STACK_OF(X509) *chain, int depth);
static int check_policy(X509_STORE_CTX *ctx);

static int get_crl_score(X509_STORE_CTX *ctx, X509 **pissuer,
    unsigned int *preasons, X509_CRL *crl, X509 *x);
static int get_crl_delta(X509_STORE_CTX *ctx,
    X509_CRL **pcrl, X509_CRL **pdcrl, X509 *x);
static void get_delta_sk(X509_STORE_CTX *ctx, X509_CRL **dcrl, int *pcrl_score,
    X509_CRL *base, STACK_OF(X509_CRL) *crls);
static void crl_akid_check(X509_STORE_CTX *ctx, X509_CRL *crl, X509 **pissuer,
    int *pcrl_score);
static int crl_crldp_check(X509 *x, X509_CRL *crl, int crl_score,
    unsigned int *preasons);
static int check_crl_path(X509_STORE_CTX *ctx, X509 *x);
static int check_crl_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *cert_path,
    STACK_OF(X509) *crl_path);
static int X509_cmp_time_internal(const ASN1_TIME *ctm, time_t *cmp_time,
    int clamp_notafter);

static int internal_verify(X509_STORE_CTX *ctx);
static int get_issuer_sk(X509 **issuer, X509_STORE_CTX *ctx, X509 *x);
static int check_key_level(X509_STORE_CTX *ctx, X509 *cert);
static int verify_cb_cert(X509_STORE_CTX *ctx, X509 *x, int depth, int err);

int ASN1_time_tm_clamp_notafter(struct tm *tm);

static int
null_callback(int ok, X509_STORE_CTX *e)
{
  return ok;
}

#if 0
static int
x509_subject_cmp(X509 **a, X509 **b)
{
  return X509_subject_name_cmp(*a, *b);
}
#endif

/* Return 1 if a certificate is self signed */
static int
cert_self_signed(X509 *x)
{
  X509_check_purpose(x, -1, 0);
  if (x->ex_flags & EXFLAG_SS)
    return 1;
  else
    return 0;
}

static int
check_id_error(X509_STORE_CTX *ctx, int errcode)
{
  ctx->error = errcode;
  ctx->current_cert = ctx->cert;
  ctx->error_depth = 0;
  return ctx->verify_cb(0, ctx);
}

static int
check_hosts(X509 *x, X509_VERIFY_PARAM_ID *id)
{
  size_t i, n;
  char *name;

  n = sk_OPENSSL_STRING_num(id->hosts);
  free(id->peername);
  id->peername = NULL;

  for (i = 0; i < n; ++i) {
    name = sk_OPENSSL_STRING_value(id->hosts, i);
    if (X509_check_host(x, name, strlen(name), id->hostflags,
        &id->peername) > 0)
      return 1;
  }
  return n == 0;
}

static int
check_id(X509_STORE_CTX *ctx)
{
  X509_VERIFY_PARAM *vpm = ctx->param;
  X509_VERIFY_PARAM_ID *id = vpm->id;
  X509 *x = ctx->cert;

  if (id->hosts && check_hosts(x, id) <= 0) {
    if (!check_id_error(ctx, X509_V_ERR_HOSTNAME_MISMATCH))
      return 0;
  }
  if (id->email != NULL && X509_check_email(x, id->email, id->emaillen, 0)
      <= 0) {
    if (!check_id_error(ctx, X509_V_ERR_EMAIL_MISMATCH))
      return 0;
  }
  if (id->ip != NULL && X509_check_ip(x, id->ip, id->iplen, 0) <= 0) {
    if (!check_id_error(ctx, X509_V_ERR_IP_ADDRESS_MISMATCH))
      return 0;
  }
  return 1;
}

int
x509_vfy_check_id(X509_STORE_CTX *ctx) {
  return check_id(ctx);
}

/*
 * This is the effectively broken legacy OpenSSL chain builder. It
 * might find an unvalidated chain and leave it sitting in
 * ctx->chain. It does not correctly handle many cases where multiple
 * chains could exist.
 *
 * Oh no.. I know a dirty word...
 * Oooooooh..
 */
static int
X509_verify_cert_legacy_build_chain(X509_STORE_CTX *ctx, int *bad, int *out_ok)
{
  X509 *x, *xtmp, *xtmp2, *chain_ss = NULL;
  int bad_chain = 0;
  X509_VERIFY_PARAM *param = ctx->param;
  int ok = 0, ret = 0;
  int depth, i;
  int num, j, retry, trust;
  int (*cb) (int xok, X509_STORE_CTX *xctx);
  STACK_OF(X509) *sktmp = NULL;

  cb = ctx->verify_cb;

  /*
   * First we make sure the chain we are going to build is
   * present and that the first entry is in place.
   */
  ctx->chain = sk_X509_new_null();
  if (ctx->chain == NULL || !sk_X509_push(ctx->chain, ctx->cert)) {
    X509error(ERR_R_MALLOC_FAILURE);
    ctx->error = X509_V_ERR_OUT_OF_MEM;
    goto end;
  }
  X509_up_ref(ctx->cert);
  ctx->num_untrusted = 1;

  /* We use a temporary STACK so we can chop and hack at it */
  if (ctx->untrusted != NULL &&
      (sktmp = sk_X509_dup(ctx->untrusted)) == NULL) {
    X509error(ERR_R_MALLOC_FAILURE);
    ctx->error = X509_V_ERR_OUT_OF_MEM;
    goto end;
  }

  num = sk_X509_num(ctx->chain);
  x = sk_X509_value(ctx->chain, num - 1);
  depth = param->depth;

  for (;;) {
    /* If we have enough, we break */
    /* FIXME: If this happens, we should take
     * note of it and, if appropriate, use the
     * X509_V_ERR_CERT_CHAIN_TOO_LONG error code
     * later.
     */
    if (depth < num)
      break;
    /* If we are self signed, we break */
    if (cert_self_signed(x))
      break;
    /*
     * If asked see if we can find issuer in trusted store first
     */
    if (ctx->param->flags & X509_V_FLAG_TRUSTED_FIRST) {
      ok = ctx->get_issuer(&xtmp, ctx, x);
      if (ok < 0) {
        ctx->error = X509_V_ERR_STORE_LOOKUP;
        goto end;
      }
      /*
       * If successful for now free up cert so it
       * will be picked up again later.
       */
      if (ok > 0) {
        X509_free(xtmp);
        break;
      }
    }
    /* If we were passed a cert chain, use it first */
    if (ctx->untrusted != NULL) {
      /*
       * If we do not find a non-expired untrusted cert, peek
       * ahead and see if we can satisify this from the trusted
       * store. If not, see if we have an expired untrusted cert.
       */
      xtmp = find_issuer(ctx, sktmp, x, 0);
      if (xtmp == NULL &&
          !(ctx->param->flags & X509_V_FLAG_TRUSTED_FIRST)) {
        ok = ctx->get_issuer(&xtmp, ctx, x);
        if (ok < 0) {
          ctx->error = X509_V_ERR_STORE_LOOKUP;
          goto end;
        }
        if (ok > 0) {
          X509_free(xtmp);
          break;
        }
        xtmp = find_issuer(ctx, sktmp, x, 1);
      }
      if (xtmp != NULL) {
        if (!sk_X509_push(ctx->chain, xtmp)) {
          X509error(ERR_R_MALLOC_FAILURE);
          ctx->error = X509_V_ERR_OUT_OF_MEM;
          ok = 0;
          goto end;
        }
        X509_up_ref(xtmp);
        (void)sk_X509_delete_ptr(sktmp, xtmp);
        ctx->num_untrusted++;
        x = xtmp;
        num++;
        /*
         * reparse the full chain for the next one
         */
        continue;
      }
    }
    break;
  }
  /* Remember how many untrusted certs we have */
  j = num;

  /*
   * At this point, chain should contain a list of untrusted
   * certificates.  We now need to add at least one trusted one,
   * if possible, otherwise we complain.
   */

  do {
    /*
     * Examine last certificate in chain and see if it is
     * self signed.
     */
    i = sk_X509_num(ctx->chain);
    x = sk_X509_value(ctx->chain, i - 1);
    if (cert_self_signed(x)) {
      /* we have a self signed certificate */
      if (i == 1) {
        /*
         * We have a single self signed
         * certificate: see if we can find it
         * in the store. We must have an exact
         * match to avoid possible
         * impersonation.
         */
        ok = ctx->get_issuer(&xtmp, ctx, x);
        if ((ok <= 0) || X509_cmp(x, xtmp)) {
          ctx->error = X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT;
          ctx->current_cert = x;
          ctx->error_depth = i - 1;
          if (ok == 1)
            X509_free(xtmp);
          bad_chain = 1;
          ok = cb(0, ctx);
          if (!ok)
            goto end;
        } else {
          /*
           * We have a match: replace
           * certificate with store
           * version so we get any trust
           * settings.
           */
          X509_free(x);
          x = xtmp;
          (void)sk_X509_set(ctx->chain, i - 1, x);
          ctx->num_untrusted = 0;
        }
      } else {
        /*
         * extract and save self signed
         * certificate for later use
         */
        chain_ss = sk_X509_pop(ctx->chain);
        ctx->num_untrusted--;
        num--;
        j--;
        x = sk_X509_value(ctx->chain, num - 1);
      }
    }
    /* We now lookup certs from the certificate store */
    for (;;) {
      /* If we have enough, we break */
      if (depth < num)
        break;
      /* If we are self signed, we break */
      if (cert_self_signed(x))
        break;
      ok = ctx->get_issuer(&xtmp, ctx, x);

      if (ok < 0) {
        ctx->error = X509_V_ERR_STORE_LOOKUP;
        goto end;
      }
      if (ok == 0)
        break;
      x = xtmp;
      if (!sk_X509_push(ctx->chain, x)) {
        X509_free(xtmp);
        X509error(ERR_R_MALLOC_FAILURE);
        ctx->error = X509_V_ERR_OUT_OF_MEM;
        ok = 0;
        goto end;
      }
      num++;
    }

    /* we now have our chain, lets check it... */
    trust = check_trust(ctx);

    /* If explicitly rejected error */
    if (trust == X509_TRUST_REJECTED) {
      ok = 0;
      goto end;
    }
    /*
     * If it's not explicitly trusted then check if there
     * is an alternative chain that could be used. We only
     * do this if we haven't already checked via
     * TRUSTED_FIRST and the user hasn't switched off
     * alternate chain checking
     */
    retry = 0;
    if (trust != X509_TRUST_TRUSTED &&
        !(ctx->param->flags & X509_V_FLAG_TRUSTED_FIRST) &&
        !(ctx->param->flags & X509_V_FLAG_NO_ALT_CHAINS)) {
      while (j-- > 1) {
        xtmp2 = sk_X509_value(ctx->chain, j - 1);
        ok = ctx->get_issuer(&xtmp, ctx, xtmp2);
        if (ok < 0)
          goto end;
        /* Check if we found an alternate chain */
        if (ok > 0) {
          /*
           * Free up the found cert
           * we'll add it again later
           */
          X509_free(xtmp);
          /*
           * Dump all the certs above
           * this point - we've found an
           * alternate chain
           */
          while (num > j) {
            xtmp = sk_X509_pop(ctx->chain);
            X509_free(xtmp);
            num--;
          }
          ctx->num_untrusted = sk_X509_num(ctx->chain);
          retry = 1;
          break;
        }
      }
    }
  } while (retry);

  /*
   * If not explicitly trusted then indicate error unless it's a single
   * self signed certificate in which case we've indicated an error already
   * and set bad_chain == 1
   */
  if (trust != X509_TRUST_TRUSTED && !bad_chain) {
    if ((chain_ss == NULL) || !ctx->check_issued(ctx, x, chain_ss)) {
      if (ctx->num_untrusted >= num)
        ctx->error = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY;
      else
        ctx->error = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT;
      ctx->current_cert = x;
    } else {
      if (!sk_X509_push(ctx->chain, chain_ss)) {
        X509error(ERR_R_MALLOC_FAILURE);
        ctx->error = X509_V_ERR_OUT_OF_MEM;
        ok = 0;
        goto end;
      }
      num++;
      ctx->num_untrusted = num;
      ctx->current_cert = chain_ss;
      ctx->error = X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN;
      chain_ss = NULL;
    }

    ctx->error_depth = num - 1;
    bad_chain = 1;
    ok = cb(0, ctx);
    if (!ok)
      goto end;
  }

  ret = 1;
 end:
  sk_X509_free(sktmp);
  X509_free(chain_ss);
  *bad = bad_chain;
  *out_ok = ok;

  return ret;
}

static int
X509_verify_cert_legacy(X509_STORE_CTX *ctx)
{
  int ok = 0, bad_chain;

  ctx->error = X509_V_OK; /* Initialize to OK */

  if (!X509_verify_cert_legacy_build_chain(ctx, &bad_chain, &ok))
    goto end;

  /* We have the chain complete: now we need to check its purpose */
  ok = check_chain_extensions(ctx);
  if (!ok)
    goto end;

  /* Check that the chain satisfies the security level. */
  ok = x509_vfy_check_security_level(ctx);
  if (!ok)
    goto end;

  /* Check name constraints */
  ok = check_name_constraints(ctx);
  if (!ok)
    goto end;

#ifndef OPENSSL_NO_RFC3779
  ok = X509v3_asid_validate_path(ctx);
  if (!ok)
    goto end;

  ok = X509v3_addr_validate_path(ctx);
  if (!ok)
    goto end;
#endif

  ok = check_id(ctx);
  if (!ok)
    goto end;

  /*
   * Check revocation status: we do this after copying parameters because
   * they may be needed for CRL signature verification.
   */
  ok = ctx->check_revocation(ctx);
  if (!ok)
    goto end;

  /* At this point, we have a chain and need to verify it */
  if (ctx->verify != NULL)
    ok = ctx->verify(ctx);
  else
    ok = internal_verify(ctx);
  if (!ok)
    goto end;

  /* If we get this far evaluate policies */
  if (!bad_chain && (ctx->param->flags & X509_V_FLAG_POLICY_CHECK))
    ok = ctx->check_policy(ctx);

 end:
  /* Safety net, error returns must set ctx->error */
  if (ok <= 0 && ctx->error == X509_V_OK)
    ctx->error = X509_V_ERR_UNSPECIFIED;

  return ok;
}

int
X509_verify_cert(X509_STORE_CTX *ctx)
{
  STACK_OF(X509) *roots = NULL;
  struct x509_verify_ctx *vctx = NULL;
  int chain_count = 0;

  if (ctx->cert == NULL) {
    X509error(X509_R_NO_CERT_SET_FOR_US_TO_VERIFY);
    ctx->error = X509_V_ERR_INVALID_CALL;
    return -1;
  }
  if (ctx->chain != NULL) {
    /*
     * This X509_STORE_CTX has already been used to verify
     * a cert. We cannot do another one.
     */
    X509error(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
    ctx->error = X509_V_ERR_INVALID_CALL;
    return -1;
  }
  if (ctx->param->id->poisoned) {
    /*
     * This X509_STORE_CTX had failures setting
     * up verify parameters. We can not use it.
     */
    X509error(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
    ctx->error = X509_V_ERR_INVALID_CALL;
    return -1;
  }
  if (ctx->error != X509_V_ERR_INVALID_CALL) {
    /*
     * This X509_STORE_CTX has not been properly initialized.
     */
    X509error(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
    ctx->error = X509_V_ERR_INVALID_CALL;
    return -1;
  }

  /*
   * If the certificate's public key is too weak, don't bother
   * continuing.
   */
  if (!check_key_level(ctx, ctx->cert) &&
      !verify_cb_cert(ctx, ctx->cert, 0, X509_V_ERR_EE_KEY_TOO_SMALL))
    return 0;

  /*
   * If flags request legacy, use the legacy verifier. If we
   * requested "no alt chains" from the age of hammer pants, use
   * the legacy verifier because the multi chain verifier really
   * does find all the "alt chains".
   *
   * XXX deprecate the NO_ALT_CHAINS flag?
   */
  if ((ctx->param->flags & X509_V_FLAG_LEGACY_VERIFY) ||
      (ctx->param->flags & X509_V_FLAG_NO_ALT_CHAINS))
    return X509_verify_cert_legacy(ctx);

  /* Use the modern multi-chain verifier from x509_verify_cert */

  if ((vctx = x509_verify_ctx_new_from_xsc(ctx)) != NULL) {
    ctx->error = X509_V_OK; /* Initialize to OK */
    chain_count = x509_verify(vctx, NULL, NULL);
  }
  x509_verify_ctx_free(vctx);

  sk_X509_pop_free(roots, X509_free);

  /* if we succeed we have a chain in ctx->chain */
  return (chain_count > 0 && ctx->chain != NULL);
}

/* Given a STACK_OF(X509) find the issuer of cert (if any)
 */

static X509 *
find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x,
    int allow_expired)
{
  int i;
  X509 *issuer, *rv = NULL;

  for (i = 0; i < sk_X509_num(sk); i++) {
    issuer = sk_X509_value(sk, i);
    if (ctx->check_issued(ctx, x, issuer)) {
      if (x509_check_cert_time(ctx, issuer, -1))
        return issuer;
      if (allow_expired)
        rv = issuer;
    }
  }
  return rv;
}

/* Given a possible certificate and issuer check them */

static int
check_issued(X509_STORE_CTX *ctx, X509 *x, X509 *issuer)
{
  int ret;

  ret = X509_check_issued(issuer, x);
  if (ret == X509_V_OK)
    return 1;
  /* If we haven't asked for issuer errors don't set ctx */
  if (!(ctx->param->flags & X509_V_FLAG_CB_ISSUER_CHECK))
    return 0;

  ctx->error = ret;
  ctx->current_cert = x;
  ctx->current_issuer = issuer;
  return ctx->verify_cb(0, ctx);
}

/* Alternative lookup method: look from a STACK stored in other_ctx */

static int
get_issuer_sk(X509 **issuer, X509_STORE_CTX *ctx, X509 *x)
{
  *issuer = find_issuer(ctx, ctx->other_ctx, x, 1);
  if (*issuer) {
    CRYPTO_add(&(*issuer)->references, 1, CRYPTO_LOCK_X509);
    return 1;
  } else
    return 0;
}

/* Check a certificate chains extensions for consistency
 * with the supplied purpose
 */

int
x509_vfy_check_chain_extensions(X509_STORE_CTX *ctx)
{
#ifdef OPENSSL_NO_CHAIN_VERIFY
  return 1;
#else
  int i, ok = 0, must_be_ca, plen = 0;
  X509 *x;
  int (*cb)(int xok, X509_STORE_CTX *xctx);
  int proxy_path_length = 0;
  int purpose;
  int allow_proxy_certs;

  cb = ctx->verify_cb;

  /* must_be_ca can have 1 of 3 values:
     -1: we accept both CA and non-CA certificates, to allow direct
         use of self-signed certificates (which are marked as CA).
     0:  we only accept non-CA certificates.  This is currently not
         used, but the possibility is present for future extensions.
     1:  we only accept CA certificates.  This is currently used for
         all certificates in the chain except the leaf certificate.
  */
  must_be_ca = -1;

  /* CRL path validation */
  if (ctx->parent) {
    allow_proxy_certs = 0;
    purpose = X509_PURPOSE_CRL_SIGN;
  } else {
    allow_proxy_certs =
        !!(ctx->param->flags & X509_V_FLAG_ALLOW_PROXY_CERTS);
    purpose = ctx->param->purpose;
  }

  /* Check all untrusted certificates */
  for (i = 0; i < ctx->num_untrusted; i++) {
    int ret;
    x = sk_X509_value(ctx->chain, i);
    if (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL) &&
        (x->ex_flags & EXFLAG_CRITICAL)) {
      ctx->error = X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION;
      ctx->error_depth = i;
      ctx->current_cert = x;
      ok = cb(0, ctx);
      if (!ok)
        goto end;
    }
    if (!allow_proxy_certs && (x->ex_flags & EXFLAG_PROXY)) {
      ctx->error = X509_V_ERR_PROXY_CERTIFICATES_NOT_ALLOWED;
      ctx->error_depth = i;
      ctx->current_cert = x;
      ok = cb(0, ctx);
      if (!ok)
        goto end;
    }
    ret = X509_check_ca(x);
    switch (must_be_ca) {
    case -1:
      if ((ctx->param->flags & X509_V_FLAG_X509_STRICT) &&
          (ret != 1) && (ret != 0)) {
        ret = 0;
        ctx->error = X509_V_ERR_INVALID_CA;
      } else
        ret = 1;
      break;
    case 0:
      if (ret != 0) {
        ret = 0;
        ctx->error = X509_V_ERR_INVALID_NON_CA;
      } else
        ret = 1;
      break;
    default:
      if ((ret == 0) ||
          ((ctx->param->flags & X509_V_FLAG_X509_STRICT) &&
          (ret != 1))) {
        ret = 0;
        ctx->error = X509_V_ERR_INVALID_CA;
      } else
        ret = 1;
      break;
    }
    if (ret == 0) {
      ctx->error_depth = i;
      ctx->current_cert = x;
      ok = cb(0, ctx);
      if (!ok)
        goto end;
    }
    if (ctx->param->purpose > 0) {
      ret = X509_check_purpose(x, purpose, must_be_ca > 0);
      if ((ret == 0) ||
          ((ctx->param->flags & X509_V_FLAG_X509_STRICT) &&
          (ret != 1))) {
        ctx->error = X509_V_ERR_INVALID_PURPOSE;
        ctx->error_depth = i;
        ctx->current_cert = x;
        ok = cb(0, ctx);
        if (!ok)
          goto end;
      }
    }
    /* Check pathlen if not self issued */
    if ((i > 1) && !(x->ex_flags & EXFLAG_SI) &&
        (x->ex_pathlen != -1) &&
        (plen > (x->ex_pathlen + proxy_path_length + 1))) {
      ctx->error = X509_V_ERR_PATH_LENGTH_EXCEEDED;
      ctx->error_depth = i;
      ctx->current_cert = x;
      ok = cb(0, ctx);
      if (!ok)
        goto end;
    }
    /* Increment path length if not self issued */
    if (!(x->ex_flags & EXFLAG_SI))
      plen++;
    /* If this certificate is a proxy certificate, the next
       certificate must be another proxy certificate or a EE
       certificate.  If not, the next certificate must be a
       CA certificate.  */
    if (x->ex_flags & EXFLAG_PROXY) {
      if (x->ex_pcpathlen != -1 && i > x->ex_pcpathlen) {
        ctx->error =
            X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED;
        ctx->error_depth = i;
        ctx->current_cert = x;
        ok = cb(0, ctx);
        if (!ok)
          goto end;
      }
      proxy_path_length++;
      must_be_ca = 0;
    } else
      must_be_ca = 1;
  }
  ok = 1;

end:
  return ok;
#endif
}

static int
check_chain_extensions(X509_STORE_CTX *ctx) {
  return x509_vfy_check_chain_extensions(ctx);
}

static int
check_name_constraints(X509_STORE_CTX *ctx)
{
  if (!x509_constraints_chain(ctx->chain, &ctx->error,
      &ctx->error_depth)) {
    ctx->current_cert = sk_X509_value(ctx->chain, ctx->error_depth);
    if (!ctx->verify_cb(0, ctx))
      return 0;
  }
  return 1;
}

/* Given a certificate try and find an exact match in the store */

static X509 *
lookup_cert_match(X509_STORE_CTX *ctx, X509 *x)
{
  STACK_OF(X509) *certs;
  X509 *xtmp = NULL;
  size_t i;

  /* Lookup all certs with matching subject name */
  certs = ctx->lookup_certs(ctx, X509_get_subject_name(x));
  if (certs == NULL)
    return NULL;

  /* Look for exact match */
  for (i = 0; i < sk_X509_num(certs); i++) {
    xtmp = sk_X509_value(certs, i);
    if (!X509_cmp(xtmp, x))
      break;
  }

  if (i < sk_X509_num(certs))
    X509_up_ref(xtmp);
  else
    xtmp = NULL;

  sk_X509_pop_free(certs, X509_free);
  return xtmp;
}

X509 *
x509_vfy_lookup_cert_match(X509_STORE_CTX *ctx, X509 *x)
{
  if (ctx->lookup_certs == NULL || ctx->store == NULL ||
      ctx->store->objs == NULL)
    return NULL;
  return lookup_cert_match(ctx, x);
}

static int
check_trust(X509_STORE_CTX *ctx)
{
  size_t i;
  int ok;
  X509 *x = NULL;
  int (*cb) (int xok, X509_STORE_CTX *xctx);

  cb = ctx->verify_cb;
  /* Check all trusted certificates in chain */
  for (i = ctx->num_untrusted; i < sk_X509_num(ctx->chain); i++) {
    x = sk_X509_value(ctx->chain, i);
    ok = X509_check_trust(x, ctx->param->trust, 0);

    /* If explicitly trusted return trusted */
    if (ok == X509_TRUST_TRUSTED)
      return X509_TRUST_TRUSTED;
    /*
     * If explicitly rejected notify callback and reject if not
     * overridden.
     */
    if (ok == X509_TRUST_REJECTED) {
      ctx->error_depth = i;
      ctx->current_cert = x;
      ctx->error = X509_V_ERR_CERT_REJECTED;
      ok = cb(0, ctx);
      if (!ok)
        return X509_TRUST_REJECTED;
    }
  }
  /*
   * If we accept partial chains and have at least one trusted certificate
   * return success.
   */
  if (ctx->param->flags & X509_V_FLAG_PARTIAL_CHAIN) {
    X509 *mx;
    if (ctx->num_untrusted < (int)sk_X509_num(ctx->chain))
      return X509_TRUST_TRUSTED;
    x = sk_X509_value(ctx->chain, 0);
    mx = lookup_cert_match(ctx, x);
    if (mx) {
      (void)sk_X509_set(ctx->chain, 0, mx);
      X509_free(x);
      ctx->num_untrusted = 0;
      return X509_TRUST_TRUSTED;
    }
  }

  /*
   * If no trusted certs in chain at all return untrusted and allow
   * standard (no issuer cert) etc errors to be indicated.
   */
  return X509_TRUST_UNTRUSTED;
}

int
x509_vfy_check_trust(X509_STORE_CTX *ctx)
{
  return check_trust(ctx);
}

static int
check_revocation(X509_STORE_CTX *ctx)
{
  int i, last, ok;

  if (!(ctx->param->flags & X509_V_FLAG_CRL_CHECK))
    return 1;
  if (ctx->param->flags & X509_V_FLAG_CRL_CHECK_ALL)
    last = sk_X509_num(ctx->chain) - 1;
  else {
    /* If checking CRL paths this isn't the EE certificate */
    if (ctx->parent)
      return 1;
    last = 0;
  }
  for (i = 0; i <= last; i++) {
    ok = check_cert(ctx, ctx->chain, i);
    if (!ok)
      return ok;
  }
  return 1;
}

int
x509_vfy_check_revocation(X509_STORE_CTX *ctx)
{
  return check_revocation(ctx);
}

static int
check_cert(X509_STORE_CTX *ctx, STACK_OF(X509) *chain, int depth)
{
  X509_CRL *crl = NULL, *dcrl = NULL;
  X509 *x;
  int ok = 0, cnum;
  unsigned int last_reasons;

  cnum = ctx->error_depth = depth;
  x = sk_X509_value(chain, cnum);
  ctx->current_cert = x;
  ctx->current_issuer = NULL;
  ctx->current_crl_score = 0;
  ctx->current_reasons = 0;
  while (ctx->current_reasons != CRLDP_ALL_REASONS) {
    last_reasons = ctx->current_reasons;
    /* Try to retrieve relevant CRL */
    if (ctx->get_crl)
      ok = ctx->get_crl(ctx, &crl, x);
    else
      ok = get_crl_delta(ctx, &crl, &dcrl, x);
    /* If error looking up CRL, nothing we can do except
     * notify callback
     */
    if (!ok) {
      ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL;
      ok = ctx->verify_cb(0, ctx);
      goto err;
    }
    ctx->current_crl = crl;
    ok = ctx->check_crl(ctx, crl);
    if (!ok)
      goto err;

    if (dcrl) {
      ok = ctx->check_crl(ctx, dcrl);
      if (!ok)
        goto err;
      ok = ctx->cert_crl(ctx, dcrl, x);
      if (!ok)
        goto err;
    } else
      ok = 1;

    /* Don't look in full CRL if delta reason is removefromCRL */
    if (ok != 2) {
      ok = ctx->cert_crl(ctx, crl, x);
      if (!ok)
        goto err;
    }

    ctx->current_crl = NULL;
    X509_CRL_free(crl);
    X509_CRL_free(dcrl);
    crl = NULL;
    dcrl = NULL;
    /* If reasons not updated we wont get anywhere by
     * another iteration, so exit loop.
     */
    if (last_reasons == ctx->current_reasons) {
      ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL;
      ok = ctx->verify_cb(0, ctx);
      goto err;
    }
  }

err:
  ctx->current_crl = NULL;
  X509_CRL_free(crl);
  X509_CRL_free(dcrl);
  return ok;
}

/* Check CRL times against values in X509_STORE_CTX */

static int
check_crl_time(X509_STORE_CTX *ctx, X509_CRL *crl, int notify)
{
  time_t *ptime;
  int i;

  if (notify)
    ctx->current_crl = crl;
  if (ctx->param->flags & X509_V_FLAG_USE_CHECK_TIME)
    ptime = &ctx->param->check_time;
  else if (ctx->param->flags & X509_V_FLAG_NO_CHECK_TIME)
    return (1);
  else
    ptime = NULL;

  i = X509_cmp_time(X509_CRL_get_lastUpdate(crl), ptime);
  if (i == 0) {
    if (!notify)
      return 0;
    ctx->error = X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD;
    if (!ctx->verify_cb(0, ctx))
      return 0;
  }

  if (i > 0) {
    if (!notify)
      return 0;
    ctx->error = X509_V_ERR_CRL_NOT_YET_VALID;
    if (!ctx->verify_cb(0, ctx))
      return 0;
  }

  if (X509_CRL_get_nextUpdate(crl)) {
    i = X509_cmp_time(X509_CRL_get_nextUpdate(crl), ptime);

    if (i == 0) {
      if (!notify)
        return 0;
      ctx->error = X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD;
      if (!ctx->verify_cb(0, ctx))
        return 0;
    }
    /* Ignore expiry of base CRL is delta is valid */
    if ((i < 0) &&
        !(ctx->current_crl_score & CRL_SCORE_TIME_DELTA)) {
      if (!notify)
        return 0;
      ctx->error = X509_V_ERR_CRL_HAS_EXPIRED;
      if (!ctx->verify_cb(0, ctx))
        return 0;
    }
  }

  if (notify)
    ctx->current_crl = NULL;

  return 1;
}

static int
get_crl_sk(X509_STORE_CTX *ctx, X509_CRL **pcrl, X509_CRL **pdcrl,
    X509 **pissuer, int *pscore, unsigned int *preasons,
    STACK_OF(X509_CRL) *crls)
{
  int i, crl_score, best_score = *pscore;
  unsigned int reasons, best_reasons = 0;
  X509 *x = ctx->current_cert;
  X509_CRL *crl, *best_crl = NULL;
  X509 *crl_issuer = NULL, *best_crl_issuer = NULL;

  for (i = 0; i < sk_X509_CRL_num(crls); i++) {
    crl = sk_X509_CRL_value(crls, i);
    reasons = *preasons;
    crl_score = get_crl_score(ctx, &crl_issuer, &reasons, crl, x);

    if (crl_score > best_score) {
      best_crl = crl;
      best_crl_issuer = crl_issuer;
      best_score = crl_score;
      best_reasons = reasons;
    }
  }

  if (best_crl) {
    if (*pcrl)
      X509_CRL_free(*pcrl);
    *pcrl = best_crl;
    *pissuer = best_crl_issuer;
    *pscore = best_score;
    *preasons = best_reasons;
    CRYPTO_add(&best_crl->references, 1, CRYPTO_LOCK_X509_CRL);
    if (*pdcrl) {
      X509_CRL_free(*pdcrl);
      *pdcrl = NULL;
    }
    get_delta_sk(ctx, pdcrl, pscore, best_crl, crls);
  }

  if (best_score >= CRL_SCORE_VALID)
    return 1;

  return 0;
}

/* Compare two CRL extensions for delta checking purposes. They should be
 * both present or both absent. If both present all fields must be identical.
 */

static int
crl_extension_match(X509_CRL *a, X509_CRL *b, int nid)
{
  ASN1_OCTET_STRING *exta, *extb;
  int i;

  i = X509_CRL_get_ext_by_NID(a, nid, -1);
  if (i >= 0) {
    /* Can't have multiple occurrences */
    if (X509_CRL_get_ext_by_NID(a, nid, i) != -1)
      return 0;
    exta = X509_EXTENSION_get_data(X509_CRL_get_ext(a, i));
  } else
    exta = NULL;

  i = X509_CRL_get_ext_by_NID(b, nid, -1);

  if (i >= 0) {
    if (X509_CRL_get_ext_by_NID(b, nid, i) != -1)
      return 0;
    extb = X509_EXTENSION_get_data(X509_CRL_get_ext(b, i));
  } else
    extb = NULL;

  if (!exta && !extb)
    return 1;

  if (!exta || !extb)
    return 0;

  if (ASN1_OCTET_STRING_cmp(exta, extb))
    return 0;

  return 1;
}

/* See if a base and delta are compatible */

static int
check_delta_base(X509_CRL *delta, X509_CRL *base)
{
  /* Delta CRL must be a delta */
  if (!delta->base_crl_number)
    return 0;
  /* Base must have a CRL number */
  if (!base->crl_number)
    return 0;
  /* Issuer names must match */
  if (X509_NAME_cmp(X509_CRL_get_issuer(base),
      X509_CRL_get_issuer(delta)))
    return 0;
  /* AKID and IDP must match */
  if (!crl_extension_match(delta, base, NID_authority_key_identifier))
    return 0;
  if (!crl_extension_match(delta, base, NID_issuing_distribution_point))
    return 0;
  /* Delta CRL base number must not exceed Full CRL number. */
  if (ASN1_INTEGER_cmp(delta->base_crl_number, base->crl_number) > 0)
    return 0;
  /* Delta CRL number must exceed full CRL number */
  if (ASN1_INTEGER_cmp(delta->crl_number, base->crl_number) > 0)
    return 1;
  return 0;
}

/* For a given base CRL find a delta... maybe extend to delta scoring
 * or retrieve a chain of deltas...
 */

static void
get_delta_sk(X509_STORE_CTX *ctx, X509_CRL **dcrl, int *pscore, X509_CRL *base,
    STACK_OF(X509_CRL) *crls)
{
  X509_CRL *delta;
  int i;

  if (!(ctx->param->flags & X509_V_FLAG_USE_DELTAS))
    return;
  if (!((ctx->current_cert->ex_flags | base->flags) & EXFLAG_FRESHEST))
    return;
  for (i = 0; i < sk_X509_CRL_num(crls); i++) {
    delta = sk_X509_CRL_value(crls, i);
    if (check_delta_base(delta, base)) {
      if (check_crl_time(ctx, delta, 0))
        *pscore |= CRL_SCORE_TIME_DELTA;
      CRYPTO_add(&delta->references, 1, CRYPTO_LOCK_X509_CRL);
      *dcrl = delta;
      return;
    }
  }
  *dcrl = NULL;
}

/* For a given CRL return how suitable it is for the supplied certificate 'x'.
 * The return value is a mask of several criteria.
 * If the issuer is not the certificate issuer this is returned in *pissuer.
 * The reasons mask is also used to determine if the CRL is suitable: if
 * no new reasons the CRL is rejected, otherwise reasons is updated.
 */

static int
get_crl_score(X509_STORE_CTX *ctx, X509 **pissuer, unsigned int *preasons,
    X509_CRL *crl, X509 *x)
{
  int crl_score = 0;
  unsigned int tmp_reasons = *preasons, crl_reasons;

  /* First see if we can reject CRL straight away */

  /* Invalid IDP cannot be processed */
  if (crl->idp_flags & IDP_INVALID)
    return 0;
  /* Reason codes or indirect CRLs need extended CRL support */
  if (!(ctx->param->flags & X509_V_FLAG_EXTENDED_CRL_SUPPORT)) {
    if (crl->idp_flags & (IDP_INDIRECT | IDP_REASONS))
      return 0;
  } else if (crl->idp_flags & IDP_REASONS) {
    /* If no new reasons reject */
    if (!(crl->idp_reasons & ~tmp_reasons))
      return 0;
  }
  /* Don't process deltas at this stage */
  else if (crl->base_crl_number)
    return 0;
  /* If issuer name doesn't match certificate need indirect CRL */
  if (X509_NAME_cmp(X509_get_issuer_name(x), X509_CRL_get_issuer(crl))) {
    if (!(crl->idp_flags & IDP_INDIRECT))
      return 0;
  } else
    crl_score |= CRL_SCORE_ISSUER_NAME;

  if (!(crl->flags & EXFLAG_CRITICAL))
    crl_score |= CRL_SCORE_NOCRITICAL;

  /* Check expiry */
  if (check_crl_time(ctx, crl, 0))
    crl_score |= CRL_SCORE_TIME;

  /* Check authority key ID and locate certificate issuer */
  crl_akid_check(ctx, crl, pissuer, &crl_score);

  /* If we can't locate certificate issuer at this point forget it */

  if (!(crl_score & CRL_SCORE_AKID))
    return 0;

  /* Check cert for matching CRL distribution points */

  if (crl_crldp_check(x, crl, crl_score, &crl_reasons)) {
    /* If no new reasons reject */
    if (!(crl_reasons & ~tmp_reasons))
      return 0;
    tmp_reasons |= crl_reasons;
    crl_score |= CRL_SCORE_SCOPE;
  }

  *preasons = tmp_reasons;

  return crl_score;
}

static void
crl_akid_check(X509_STORE_CTX *ctx, X509_CRL *crl, X509 **pissuer,
    int *pcrl_score)
{
  X509 *crl_issuer = NULL;
  X509_NAME *cnm = X509_CRL_get_issuer(crl);
  int cidx = ctx->error_depth;
  int i;

  if (cidx != sk_X509_num(ctx->chain) - 1)
    cidx++;

  crl_issuer = sk_X509_value(ctx->chain, cidx);

  if (X509_check_akid(crl_issuer, crl->akid) == X509_V_OK) {
    if (*pcrl_score & CRL_SCORE_ISSUER_NAME) {
      *pcrl_score |= CRL_SCORE_AKID|CRL_SCORE_ISSUER_CERT;
      *pissuer = crl_issuer;
      return;
    }
  }

  for (cidx++; cidx < sk_X509_num(ctx->chain); cidx++) {
    crl_issuer = sk_X509_value(ctx->chain, cidx);
    if (X509_NAME_cmp(X509_get_subject_name(crl_issuer), cnm))
      continue;
    if (X509_check_akid(crl_issuer, crl->akid) == X509_V_OK) {
      *pcrl_score |= CRL_SCORE_AKID|CRL_SCORE_SAME_PATH;
      *pissuer = crl_issuer;
      return;
    }
  }

  /* Anything else needs extended CRL support */

  if (!(ctx->param->flags & X509_V_FLAG_EXTENDED_CRL_SUPPORT))
    return;

  /* Otherwise the CRL issuer is not on the path. Look for it in the
   * set of untrusted certificates.
   */
  for (i = 0; i < sk_X509_num(ctx->untrusted); i++) {
    crl_issuer = sk_X509_value(ctx->untrusted, i);
    if (X509_NAME_cmp(X509_get_subject_name(crl_issuer), cnm))
      continue;
    if (X509_check_akid(crl_issuer, crl->akid) == X509_V_OK) {
      *pissuer = crl_issuer;
      *pcrl_score |= CRL_SCORE_AKID;
      return;
    }
  }
}

/* Check the path of a CRL issuer certificate. This creates a new
 * X509_STORE_CTX and populates it with most of the parameters from the
 * parent. This could be optimised somewhat since a lot of path checking
 * will be duplicated by the parent, but this will rarely be used in
 * practice.
 */

static int
check_crl_path(X509_STORE_CTX *ctx, X509 *x)
{
  X509_STORE_CTX crl_ctx;
  int ret;

  /* Don't allow recursive CRL path validation */
  if (ctx->parent)
    return 0;
  if (!X509_STORE_CTX_init(&crl_ctx, ctx->store, x, ctx->untrusted)) {
    ret = -1;
    goto err;
  }

  crl_ctx.crls = ctx->crls;
  /* Copy verify params across */
  X509_STORE_CTX_set0_param(&crl_ctx, ctx->param);

  crl_ctx.parent = ctx;
  crl_ctx.verify_cb = ctx->verify_cb;

  /* Verify CRL issuer */
  ret = X509_verify_cert(&crl_ctx);

  if (ret <= 0)
    goto err;

  /* Check chain is acceptable */
  ret = check_crl_chain(ctx, ctx->chain, crl_ctx.chain);

err:
  X509_STORE_CTX_cleanup(&crl_ctx);
  return ret;
}

/* RFC3280 says nothing about the relationship between CRL path
 * and certificate path, which could lead to situations where a
 * certificate could be revoked or validated by a CA not authorised
 * to do so. RFC5280 is more strict and states that the two paths must
 * end in the same trust anchor, though some discussions remain...
 * until this is resolved we use the RFC5280 version
 */

static int
check_crl_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *cert_path,
    STACK_OF(X509) *crl_path)
{
  X509 *cert_ta, *crl_ta;

  cert_ta = sk_X509_value(cert_path, sk_X509_num(cert_path) - 1);
  crl_ta = sk_X509_value(crl_path, sk_X509_num(crl_path) - 1);
  if (!X509_cmp(cert_ta, crl_ta))
    return 1;
  return 0;
}

/* Check for match between two dist point names: three separate cases.
 * 1. Both are relative names and compare X509_NAME types.
 * 2. One full, one relative. Compare X509_NAME to GENERAL_NAMES.
 * 3. Both are full names and compare two GENERAL_NAMES.
 * 4. One is NULL: automatic match.
 */

static int
idp_check_dp(DIST_POINT_NAME *a, DIST_POINT_NAME *b)
{
  X509_NAME *nm = NULL;
  GENERAL_NAMES *gens = NULL;
  GENERAL_NAME *gena, *genb;
  int i, j;

  if (!a || !b)
    return 1;
  if (a->type == 1) {
    if (!a->dpname)
      return 0;
    /* Case 1: two X509_NAME */
    if (b->type == 1) {
      if (!b->dpname)
        return 0;
      if (!X509_NAME_cmp(a->dpname, b->dpname))
        return 1;
      else
        return 0;
    }
    /* Case 2: set name and GENERAL_NAMES appropriately */
    nm = a->dpname;
    gens = b->name.fullname;
  } else if (b->type == 1) {
    if (!b->dpname)
      return 0;
    /* Case 2: set name and GENERAL_NAMES appropriately */
    gens = a->name.fullname;
    nm = b->dpname;
  }

  /* Handle case 2 with one GENERAL_NAMES and one X509_NAME */
  if (nm) {
    for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
      gena = sk_GENERAL_NAME_value(gens, i);
      if (gena->type != GEN_DIRNAME)
        continue;
      if (!X509_NAME_cmp(nm, gena->d.directoryName))
        return 1;
    }
    return 0;
  }

  /* Else case 3: two GENERAL_NAMES */

  for (i = 0; i < sk_GENERAL_NAME_num(a->name.fullname); i++) {
    gena = sk_GENERAL_NAME_value(a->name.fullname, i);
    for (j = 0; j < sk_GENERAL_NAME_num(b->name.fullname); j++) {
      genb = sk_GENERAL_NAME_value(b->name.fullname, j);
      if (!GENERAL_NAME_cmp(gena, genb))
        return 1;
    }
  }

  return 0;
}

static int
crldp_check_crlissuer(DIST_POINT *dp, X509_CRL *crl, int crl_score)
{
  int i;
  X509_NAME *nm = X509_CRL_get_issuer(crl);

  /* If no CRLissuer return is successful iff don't need a match */
  if (!dp->CRLissuer)
    return !!(crl_score & CRL_SCORE_ISSUER_NAME);
  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)
      continue;
    if (!X509_NAME_cmp(gen->d.directoryName, nm))
      return 1;
  }
  return 0;
}

/* Check CRLDP and IDP */

static int
crl_crldp_check(X509 *x, X509_CRL *crl, int crl_score, unsigned int *preasons)
{
  int i;

  if (crl->idp_flags & IDP_ONLYATTR)
    return 0;
  if (x->ex_flags & EXFLAG_CA) {
    if (crl->idp_flags & IDP_ONLYUSER)
      return 0;
  } else {
    if (crl->idp_flags & IDP_ONLYCA)
      return 0;
  }
  *preasons = crl->idp_reasons;
  for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) {
    DIST_POINT *dp = sk_DIST_POINT_value(x->crldp, i);
    if (crldp_check_crlissuer(dp, crl, crl_score)) {
      if (!crl->idp ||
          idp_check_dp(dp->distpoint, crl->idp->distpoint)) {
        *preasons &= dp->dp_reasons;
        return 1;
      }
    }
  }
  if ((!crl->idp || !crl->idp->distpoint) &&
      (crl_score & CRL_SCORE_ISSUER_NAME))
    return 1;
  return 0;
}

/* Retrieve CRL corresponding to current certificate.
 * If deltas enabled try to find a delta CRL too
 */

static int
get_crl_delta(X509_STORE_CTX *ctx, X509_CRL **pcrl, X509_CRL **pdcrl, X509 *x)
{
  int ok;
  X509 *issuer = NULL;
  int crl_score = 0;
  unsigned int reasons;
  X509_CRL *crl = NULL, *dcrl = NULL;
  STACK_OF(X509_CRL) *skcrl;
  X509_NAME *nm = X509_get_issuer_name(x);

  reasons = ctx->current_reasons;
  ok = get_crl_sk(ctx, &crl, &dcrl, &issuer, &crl_score, &reasons,
      ctx->crls);
  if (ok)
    goto done;

  /* Lookup CRLs from store */
  skcrl = ctx->lookup_crls(ctx, nm);

  /* If no CRLs found and a near match from get_crl_sk use that */
  if (!skcrl && crl)
    goto done;

  get_crl_sk(ctx, &crl, &dcrl, &issuer, &crl_score, &reasons, skcrl);

  sk_X509_CRL_pop_free(skcrl, X509_CRL_free);

done:

  /* If we got any kind of CRL use it and return success */
  if (crl) {
    ctx->current_issuer = issuer;
    ctx->current_crl_score = crl_score;
    ctx->current_reasons = reasons;
    *pcrl = crl;
    *pdcrl = dcrl;
    return 1;
  }

  return 0;
}

/* Check CRL validity */
static int
check_crl(X509_STORE_CTX *ctx, X509_CRL *crl)
{
  X509 *issuer = NULL;
  EVP_PKEY *ikey = NULL;
  int ok = 0, chnum, cnum;

  cnum = ctx->error_depth;
  chnum = sk_X509_num(ctx->chain) - 1;
  /* if we have an alternative CRL issuer cert use that */
  if (ctx->current_issuer) {
    issuer = ctx->current_issuer;
  } else if (cnum < chnum) {
    /*
     * Else find CRL issuer: if not last certificate then issuer
     * is next certificate in chain.
     */
    issuer = sk_X509_value(ctx->chain, cnum + 1);
  } else {
    issuer = sk_X509_value(ctx->chain, chnum);
    /* If not self signed, can't check signature */
    if (!ctx->check_issued(ctx, issuer, issuer)) {
      ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER;
      ok = ctx->verify_cb(0, ctx);
      if (!ok)
        goto err;
    }
  }

  if (issuer) {
    /* Skip most tests for deltas because they have already
     * been done
     */
    if (!crl->base_crl_number) {
      /* Check for cRLSign bit if keyUsage present */
      if ((issuer->ex_flags & EXFLAG_KUSAGE) &&
          !(issuer->ex_kusage & KU_CRL_SIGN)) {
        ctx->error = X509_V_ERR_KEYUSAGE_NO_CRL_SIGN;
        ok = ctx->verify_cb(0, ctx);
        if (!ok)
          goto err;
      }

      if (!(ctx->current_crl_score & CRL_SCORE_SCOPE)) {
        ctx->error = X509_V_ERR_DIFFERENT_CRL_SCOPE;
        ok = ctx->verify_cb(0, ctx);
        if (!ok)
          goto err;
      }

      if (!(ctx->current_crl_score & CRL_SCORE_SAME_PATH)) {
        if (check_crl_path(ctx,
            ctx->current_issuer) <= 0) {
          ctx->error = X509_V_ERR_CRL_PATH_VALIDATION_ERROR;
          ok = ctx->verify_cb(0, ctx);
          if (!ok)
            goto err;
        }
      }

      if (crl->idp_flags & IDP_INVALID) {
        ctx->error = X509_V_ERR_INVALID_EXTENSION;
        ok = ctx->verify_cb(0, ctx);
        if (!ok)
          goto err;
      }


    }

    if (!(ctx->current_crl_score & CRL_SCORE_TIME)) {
      ok = check_crl_time(ctx, crl, 1);
      if (!ok)
        goto err;
    }

    /* Attempt to get issuer certificate public key */
    ikey = X509_get_pubkey(issuer);

    if (!ikey) {
      ctx->error = X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY;
      ok = ctx->verify_cb(0, ctx);
      if (!ok)
        goto err;
    } else {
      /* Verify CRL signature */
      if (X509_CRL_verify(crl, ikey) <= 0) {
        ctx->error = X509_V_ERR_CRL_SIGNATURE_FAILURE;
        ok = ctx->verify_cb(0, ctx);
        if (!ok)
          goto err;
      }
    }
  }

  ok = 1;

err:
  EVP_PKEY_free(ikey);
  return ok;
}

/* Check certificate against CRL */
static int
cert_crl(X509_STORE_CTX *ctx, X509_CRL *crl, X509 *x)
{
  int ok;
  X509_REVOKED *rev;

  /* The rules changed for this... previously if a CRL contained
   * unhandled critical extensions it could still be used to indicate
   * a certificate was revoked. This has since been changed since
   * critical extension can change the meaning of CRL entries.
   */
  if (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL) &&
      (crl->flags & EXFLAG_CRITICAL)) {
    ctx->error = X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION;
    ok = ctx->verify_cb(0, ctx);
    if (!ok)
      return 0;
  }
  /* Look for serial number of certificate in CRL
   * If found make sure reason is not removeFromCRL.
   */
  if (X509_CRL_get0_by_cert(crl, &rev, x)) {
    if (rev->reason == CRL_REASON_REMOVE_FROM_CRL)
      return 2;
    ctx->error = X509_V_ERR_CERT_REVOKED;
    ok = ctx->verify_cb(0, ctx);
    if (!ok)
      return 0;
  }

  return 1;
}

int
x509_vfy_check_policy(X509_STORE_CTX *ctx)
{
  int ret;

  if (ctx->parent)
    return 1;

  /* X509_policy_check always allocates a new tree. */
  X509_policy_tree_free(ctx->tree);
  ctx->tree = NULL;

  ret = X509_policy_check(&ctx->tree, &ctx->explicit_policy, ctx->chain,
      ctx->param->policies, ctx->param->flags);
  if (ret == 0) {
    X509error(ERR_R_MALLOC_FAILURE);
    return 0;
  }
  /* Invalid or inconsistent extensions */
  if (ret == -1) {
    /* Locate certificates with bad extensions and notify
     * callback.
     */
    X509 *x;
    int i;
    for (i = 1; i < sk_X509_num(ctx->chain); i++) {
      x = sk_X509_value(ctx->chain, i);
      if (!(x->ex_flags & EXFLAG_INVALID_POLICY))
        continue;
      ctx->current_cert = x;
      ctx->error = X509_V_ERR_INVALID_POLICY_EXTENSION;
      if (!ctx->verify_cb(0, ctx))
        return 0;
    }
    return 1;
  }
  if (ret == -2) {
    ctx->current_cert = NULL;
    ctx->error = X509_V_ERR_NO_EXPLICIT_POLICY;
    return ctx->verify_cb(0, ctx);
  }

  if (ctx->param->flags & X509_V_FLAG_NOTIFY_POLICY) {
    ctx->current_cert = NULL;
    ctx->error = X509_V_OK;
    if (!ctx->verify_cb(2, ctx))
      return 0;
  }

  return 1;
}

static int
check_policy(X509_STORE_CTX *ctx)
{
  return x509_vfy_check_policy(ctx);
}

/*
 * Inform the verify callback of an error.
 *
 * If x is not NULL it is the error cert, otherwise use the chain cert
 * at depth.
 *
 * If err is not X509_V_OK, that's the error value, otherwise leave
 * unchanged (presumably set by the caller).
 *
 * Returns 0 to abort verification with an error, non-zero to continue.
 */
static int
verify_cb_cert(X509_STORE_CTX *ctx, X509 *x, int depth, int err)
{
  ctx->error_depth = depth;
  ctx->current_cert = (x != NULL) ? x : sk_X509_value(ctx->chain, depth);
  if (err != X509_V_OK)
    ctx->error = err;
  return ctx->verify_cb(0, ctx);
}


/* Mimic OpenSSL '0 for failure' ick */
static int
time_t_bogocmp(time_t a, time_t b)
{
  if (a == -1 || b == -1)
    return 0;
  if (a <= b)
    return -1;
  return 1;
}

/*
 * Check certificate validity times.
 *
 * If depth >= 0, invoke verification callbacks on error, otherwise just return
 * the validation status.
 *
 * Return 1 on success, 0 otherwise.
 */
int
x509_check_cert_time(X509_STORE_CTX *ctx, X509 *x, int depth)
{
  time_t ptime;
  int i;

  if (ctx->param->flags & X509_V_FLAG_USE_CHECK_TIME)
    ptime = ctx->param->check_time;
  else if (ctx->param->flags & X509_V_FLAG_NO_CHECK_TIME)
    return 1;
  else
    ptime = time(NULL);

  if (x->ex_flags & EXFLAG_SET)
    i = time_t_bogocmp(x->not_before, ptime);
  else
    i = X509_cmp_time(X509_get_notBefore(x), &ptime);

  if (i >= 0 && depth < 0)
    return 0;
  if (i == 0 && !verify_cb_cert(ctx, x, depth,
      X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD))
    return 0;
  if (i > 0 && !verify_cb_cert(ctx, x, depth,
      X509_V_ERR_CERT_NOT_YET_VALID))
    return 0;

  if (x->ex_flags & EXFLAG_SET)
    i = time_t_bogocmp(x->not_after, ptime);
  else
    i = X509_cmp_time_internal(X509_get_notAfter(x), &ptime, 1);

  if (i <= 0 && depth < 0)
    return 0;
  if (i == 0 && !verify_cb_cert(ctx, x, depth,
      X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD))
    return 0;
  if (i < 0 && !verify_cb_cert(ctx, x, depth,
      X509_V_ERR_CERT_HAS_EXPIRED))
    return 0;

  return 1;
}

static int
x509_vfy_internal_verify(X509_STORE_CTX *ctx, int chain_verified)
{
  int n = sk_X509_num(ctx->chain) - 1;
  X509 *xi = sk_X509_value(ctx->chain, n);
  X509 *xs;

  if (ctx->check_issued(ctx, xi, xi))
    xs = xi;
  else {
    if (ctx->param->flags & X509_V_FLAG_PARTIAL_CHAIN) {
      xs = xi;
      goto check_cert;
    }
    if (n <= 0)
      return verify_cb_cert(ctx, xi, 0,
          X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE);
    n--;
    ctx->error_depth = n;
    xs = sk_X509_value(ctx->chain, n);
  }

  /*
   * Do not clear ctx->error=0, it must be "sticky", only the
   * user's callback is allowed to reset errors (at its own
   * peril).
   */
  while (n >= 0) {

    /*
     * Skip signature check for self signed certificates
     * unless explicitly asked for.  It doesn't add any
     * security and just wastes time.  If the issuer's
     * public key is unusable, report the issuer
     * certificate and its depth (rather than the depth of
     * the subject).
     */
    if (!chain_verified && ( xs != xi ||
        (ctx->param->flags & X509_V_FLAG_CHECK_SS_SIGNATURE))) {
      EVP_PKEY *pkey;
      if ((pkey = X509_get_pubkey(xi)) == NULL) {
        if (!verify_cb_cert(ctx, xi, xi != xs ? n+1 : n,
            X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY))
          return 0;
      } else if (X509_verify(xs, pkey) <= 0) {
        if (!verify_cb_cert(ctx, xs, n,
            X509_V_ERR_CERT_SIGNATURE_FAILURE)) {
          EVP_PKEY_free(pkey);
          return 0;
        }
      }
      EVP_PKEY_free(pkey);
    }
check_cert:
    /* Calls verify callback as needed */
    if (!chain_verified && !x509_check_cert_time(ctx, xs, n))
      return 0;

    /*
     * Signal success at this depth.  However, the
     * previous error (if any) is retained.
     */
    ctx->current_issuer = xi;
    ctx->current_cert = xs;
    ctx->error_depth = n;
    if (!ctx->verify_cb(1, ctx))
      return 0;

    if (--n >= 0) {
      xi = xs;
      xs = sk_X509_value(ctx->chain, n);
    }
  }
  return 1;
}

static int
internal_verify(X509_STORE_CTX *ctx)
{
  return x509_vfy_internal_verify(ctx, 0);
}

/*
 * Internal verify, but with a chain where the verification
 * math has already been performed.
 */
int
x509_vfy_callback_indicate_completion(X509_STORE_CTX *ctx)
{
  return x509_vfy_internal_verify(ctx, 1);
}

int
X509_cmp_current_time(const ASN1_TIME *ctm)
{
  return X509_cmp_time(ctm, NULL);
}

/*
 * Compare a possibly unvalidated ASN1_TIME string against a time_t
 * using RFC 5280 rules for the time string. If *cmp_time is NULL
 * the current system time is used.
 *
 * XXX NOTE that unlike what you expect a "cmp" function to do in C,
 * XXX this one is "special", and returns 0 for error.
 *
 * Returns:
 * -1 if the ASN1_time is earlier than OR the same as *cmp_time.
 * 1 if the ASN1_time is later than *cmp_time.
 * 0 on error.
 */
static int
X509_cmp_time_internal(const ASN1_TIME *ctm, time_t *cmp_time, int is_notafter)
{
  time_t compare, cert_time;

  if (cmp_time == NULL)
    compare = time(NULL);
  else
    compare = *cmp_time;

  if ((cert_time = x509_verify_asn1_time_to_time_t(ctm, is_notafter)) ==
      -1)
    return 0; /* invalid time */

  if (cert_time <= compare)
    return -1; /* 0 is used for error, so map same to less than */

  return 1;
}

int
X509_cmp_time(const ASN1_TIME *ctm, time_t *cmp_time)
{
  return X509_cmp_time_internal(ctm, cmp_time, 0);
}


ASN1_TIME *
X509_gmtime_adj(ASN1_TIME *s, long adj)
{
  return X509_time_adj(s, adj, NULL);
}

ASN1_TIME *
X509_time_adj(ASN1_TIME *s, long offset_sec, time_t *in_time)
{
  return X509_time_adj_ex(s, 0, offset_sec, in_time);
}

ASN1_TIME *
X509_time_adj_ex(ASN1_TIME *s, int offset_day, long offset_sec, time_t *in_time)
{
  time_t t;
  if (in_time == NULL)
    t = time(NULL);
  else
    t = *in_time;

  return ASN1_TIME_adj(s, t, offset_day, offset_sec);
}

int
X509_get_pubkey_parameters(EVP_PKEY *pkey, STACK_OF(X509) *chain)
{
  EVP_PKEY *ktmp = NULL, *ktmp2;
  int i, j;

  if ((pkey != NULL) && !EVP_PKEY_missing_parameters(pkey))
    return 1;

  for (i = 0; i < sk_X509_num(chain); i++) {
    ktmp = X509_get0_pubkey(sk_X509_value(chain, i));
    if (ktmp == NULL) {
      X509error(X509_R_UNABLE_TO_GET_CERTS_PUBLIC_KEY);
      return 0;
    }
    if (!EVP_PKEY_missing_parameters(ktmp))
      break;
    else
      ktmp = NULL;
  }
  if (ktmp == NULL) {
    X509error(X509_R_UNABLE_TO_FIND_PARAMETERS_IN_CHAIN);
    return 0;
  }

  /* first, populate the other certs */
  for (j = i - 1; j >= 0; j--) {
    if ((ktmp2 = X509_get0_pubkey(sk_X509_value(chain, j))) == NULL)
      return 0;
    if (!EVP_PKEY_copy_parameters(ktmp2, ktmp))
      return 0;
  }

  if (pkey != NULL)
    if (!EVP_PKEY_copy_parameters(pkey, ktmp))
      return 0;
  return 1;
}

int
X509_STORE_CTX_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func,
    CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func)
{
  /* This function is (usually) called only once, by
   * SSL_get_ex_data_X509_STORE_CTX_idx (ssl/ssl_cert.c). */
  return CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_X509_STORE_CTX,
      argl, argp, new_func, dup_func, free_func);
}

int
X509_STORE_CTX_set_ex_data(X509_STORE_CTX *ctx, int idx, void *data)
{
  return CRYPTO_set_ex_data(&ctx->ex_data, idx, data);
}

void *
X509_STORE_CTX_get_ex_data(X509_STORE_CTX *ctx, int idx)
{
  return CRYPTO_get_ex_data(&ctx->ex_data, idx);
}

int
X509_STORE_CTX_get_error(X509_STORE_CTX *ctx)
{
  return ctx->error;
}

void
X509_STORE_CTX_set_error(X509_STORE_CTX *ctx, int err)
{
  ctx->error = err;
}

int
X509_STORE_CTX_get_error_depth(X509_STORE_CTX *ctx)
{
  return ctx->error_depth;
}

void
X509_STORE_CTX_set_error_depth(X509_STORE_CTX *ctx, int depth)
{
  ctx->error_depth = depth;
}

X509 *
X509_STORE_CTX_get_current_cert(X509_STORE_CTX *ctx)
{
  return ctx->current_cert;
}

void
X509_STORE_CTX_set_current_cert(X509_STORE_CTX *ctx, X509 *x)
{
  ctx->current_cert = x;
}

STACK_OF(X509) *
X509_STORE_CTX_get_chain(X509_STORE_CTX *ctx)
{
  return ctx->chain;
}

STACK_OF(X509) *
X509_STORE_CTX_get0_chain(X509_STORE_CTX *xs)
{
  return xs->chain;
}

STACK_OF(X509) *
X509_STORE_CTX_get1_chain(X509_STORE_CTX *ctx)
{
  int i;
  X509 *x;
  STACK_OF(X509) *chain;

  if (!ctx->chain || !(chain = sk_X509_dup(ctx->chain)))
    return NULL;
  for (i = 0; i < sk_X509_num(chain); i++) {
    x = sk_X509_value(chain, i);
    CRYPTO_add(&x->references, 1, CRYPTO_LOCK_X509);
  }
  return chain;
}

X509 *
X509_STORE_CTX_get0_current_issuer(X509_STORE_CTX *ctx)
{
  return ctx->current_issuer;
}

X509_CRL *
X509_STORE_CTX_get0_current_crl(X509_STORE_CTX *ctx)
{
  return ctx->current_crl;
}

X509_STORE_CTX *
X509_STORE_CTX_get0_parent_ctx(X509_STORE_CTX *ctx)
{
  return ctx->parent;
}

X509_STORE *
X509_STORE_CTX_get0_store(X509_STORE_CTX *xs)
{
  return xs->store;
}

void
X509_STORE_CTX_set_cert(X509_STORE_CTX *ctx, X509 *x)
{
  ctx->cert = x;
}

void
X509_STORE_CTX_set_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
  ctx->untrusted = sk;
}

void
X509_STORE_CTX_set0_crls(X509_STORE_CTX *ctx, STACK_OF(X509_CRL) *sk)
{
  ctx->crls = sk;
}

int
X509_STORE_CTX_set_purpose(X509_STORE_CTX *ctx, int purpose)
{
  return X509_STORE_CTX_purpose_inherit(ctx, 0, purpose, 0);
}

int
X509_STORE_CTX_set_trust(X509_STORE_CTX *ctx, int trust)
{
  return X509_STORE_CTX_purpose_inherit(ctx, 0, 0, trust);
}

/* This function is used to set the X509_STORE_CTX purpose and trust
 * values. This is intended to be used when another structure has its
 * own trust and purpose values which (if set) will be inherited by
 * the ctx. If they aren't set then we will usually have a default
 * purpose in mind which should then be used to set the trust value.
 * An example of this is SSL use: an SSL structure will have its own
 * purpose and trust settings which the application can set: if they
 * aren't set then we use the default of SSL client/server.
 */

int
X509_STORE_CTX_purpose_inherit(X509_STORE_CTX *ctx, int def_purpose,
    int purpose, int trust)
{
  int idx;

  /* If purpose not set use default */
  if (!purpose)
    purpose = def_purpose;
  /* If we have a purpose then check it is valid */
  if (purpose) {
    X509_PURPOSE *ptmp;
    idx = X509_PURPOSE_get_by_id(purpose);
    if (idx == -1) {
      X509error(X509_R_UNKNOWN_PURPOSE_ID);
      return 0;
    }
    ptmp = X509_PURPOSE_get0(idx);
    if (ptmp->trust == X509_TRUST_DEFAULT) {
      idx = X509_PURPOSE_get_by_id(def_purpose);
      if (idx == -1) {
        X509error(X509_R_UNKNOWN_PURPOSE_ID);
        return 0;
      }
      ptmp = X509_PURPOSE_get0(idx);
    }
    /* If trust not set then get from purpose default */
    if (!trust)
      trust = ptmp->trust;
  }
  if (trust) {
    idx = X509_TRUST_get_by_id(trust);
    if (idx == -1) {
      X509error(X509_R_UNKNOWN_TRUST_ID);
      return 0;
    }
  }

  if (purpose && !ctx->param->purpose)
    ctx->param->purpose = purpose;
  if (trust && !ctx->param->trust)
    ctx->param->trust = trust;
  return 1;
}

X509_STORE_CTX *
X509_STORE_CTX_new(void)
{
  X509_STORE_CTX *ctx;

  ctx = calloc(1, sizeof(X509_STORE_CTX));
  if (!ctx) {
    X509error(ERR_R_MALLOC_FAILURE);
    return NULL;
  }
  return ctx;
}

void
X509_STORE_CTX_free(X509_STORE_CTX *ctx)
{
  if (ctx == NULL)
    return;

  X509_STORE_CTX_cleanup(ctx);
  free(ctx);
}

int
X509_STORE_CTX_init(X509_STORE_CTX *ctx, X509_STORE *store, X509 *x509,
    STACK_OF(X509) *chain)
{
  int param_ret = 1;

  /*
   * Make sure everything is initialized properly even in case of an
   * early return due to an error.
   *
   * While this 'ctx' can be reused, X509_STORE_CTX_cleanup() will have
   * freed everything and memset ex_data anyway.  This also allows us
   * to safely use X509_STORE_CTX variables from the stack which will
   * have uninitialized data.
   */
  memset(ctx, 0, sizeof(*ctx));

  /*
   * Start with this set to not valid - it will be set to valid
   * in X509_verify_cert.
   */
  ctx->error = X509_V_ERR_INVALID_CALL;

  /*
   * Set values other than 0.  Keep this in the same order as
   * X509_STORE_CTX except for values that may fail.  All fields that
   * may fail should go last to make sure 'ctx' is as consistent as
   * possible even on early exits.
   */
  ctx->store = store;
  ctx->cert = x509;
  ctx->untrusted = chain;

  if (store && store->verify)
    ctx->verify = store->verify;
  else
    ctx->verify = internal_verify;

  if (store && store->verify_cb)
    ctx->verify_cb = store->verify_cb;
  else
    ctx->verify_cb = null_callback;

  if (store && store->get_issuer)
    ctx->get_issuer = store->get_issuer;
  else
    ctx->get_issuer = X509_STORE_CTX_get1_issuer;

  if (store && store->check_issued)
    ctx->check_issued = store->check_issued;
  else
    ctx->check_issued = check_issued;

  if (store && store->check_revocation)
    ctx->check_revocation = store->check_revocation;
  else
    ctx->check_revocation = check_revocation;

  if (store && store->get_crl)
    ctx->get_crl = store->get_crl;
  else
    ctx->get_crl = NULL;

  if (store && store->check_crl)
    ctx->check_crl = store->check_crl;
  else
    ctx->check_crl = check_crl;

  if (store && store->cert_crl)
    ctx->cert_crl = store->cert_crl;
  else
    ctx->cert_crl = cert_crl;

  ctx->check_policy = check_policy;

  if (store && store->lookup_certs)
    ctx->lookup_certs = store->lookup_certs;
  else
    ctx->lookup_certs = X509_STORE_get1_certs;

  if (store && store->lookup_crls)
    ctx->lookup_crls = store->lookup_crls;
  else
    ctx->lookup_crls = X509_STORE_get1_crls;

  if (store && store->cleanup)
    ctx->cleanup = store->cleanup;
  else
    ctx->cleanup = NULL;

  ctx->param = X509_VERIFY_PARAM_new();
  if (!ctx->param) {
    X509error(ERR_R_MALLOC_FAILURE);
    return 0;
  }

  /* Inherit callbacks and flags from X509_STORE if not set
   * use defaults.
   */
  if (store)
    param_ret = X509_VERIFY_PARAM_inherit(ctx->param, store->param);
  else
    ctx->param->inh_flags |= X509_VP_FLAG_DEFAULT|X509_VP_FLAG_ONCE;

  if (param_ret)
    param_ret = X509_VERIFY_PARAM_inherit(ctx->param,
        X509_VERIFY_PARAM_lookup("default"));

  if (param_ret == 0) {
    X509error(ERR_R_MALLOC_FAILURE);
    return 0;
  }

  if (CRYPTO_new_ex_data(CRYPTO_EX_INDEX_X509_STORE_CTX, ctx,
      &(ctx->ex_data)) == 0) {
    X509error(ERR_R_MALLOC_FAILURE);
    return 0;
  }
  return 1;
}

/* Set alternative lookup method: just a STACK of trusted certificates.
 * This avoids X509_STORE nastiness where it isn't needed.
 */

void
X509_STORE_CTX_trusted_stack(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
  ctx->other_ctx = sk;
  ctx->get_issuer = get_issuer_sk;
}

void
X509_STORE_CTX_set0_trusted_stack(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
  X509_STORE_CTX_trusted_stack(ctx, sk);
}

void
X509_STORE_CTX_cleanup(X509_STORE_CTX *ctx)
{
  if (ctx->cleanup)
    ctx->cleanup(ctx);
  if (ctx->param != NULL) {
    if (ctx->parent == NULL)
      X509_VERIFY_PARAM_free(ctx->param);
    ctx->param = NULL;
  }
  if (ctx->tree != NULL) {
    X509_policy_tree_free(ctx->tree);
    ctx->tree = NULL;
  }
  if (ctx->chain != NULL) {
    sk_X509_pop_free(ctx->chain, X509_free);
    ctx->chain = NULL;
  }
  CRYPTO_free_ex_data(CRYPTO_EX_INDEX_X509_STORE_CTX,
      ctx, &(ctx->ex_data));
  memset(&ctx->ex_data, 0, sizeof(CRYPTO_EX_DATA));
}

void
X509_STORE_CTX_set_depth(X509_STORE_CTX *ctx, int depth)
{
  X509_VERIFY_PARAM_set_depth(ctx->param, depth);
}

void
X509_STORE_CTX_set_flags(X509_STORE_CTX *ctx, unsigned long flags)
{
  X509_VERIFY_PARAM_set_flags(ctx->param, flags);
}

void
X509_STORE_CTX_set_time(X509_STORE_CTX *ctx, unsigned long flags, time_t t)
{
  X509_VERIFY_PARAM_set_time(ctx->param, t);
}

int
(*X509_STORE_CTX_get_verify_cb(X509_STORE_CTX *ctx))(int, X509_STORE_CTX *)
{
  return ctx->verify_cb;
}

void
X509_STORE_CTX_set_verify_cb(X509_STORE_CTX *ctx,
    int (*verify_cb)(int, X509_STORE_CTX *))
{
  ctx->verify_cb = verify_cb;
}

int
(*X509_STORE_CTX_get_verify(X509_STORE_CTX *ctx))(X509_STORE_CTX *)
{
  return ctx->verify;
}

void
X509_STORE_CTX_set_verify(X509_STORE_CTX *ctx, int (*verify)(X509_STORE_CTX *))
{
  ctx->verify = verify;
}

X509 *
X509_STORE_CTX_get0_cert(X509_STORE_CTX *ctx)
{
  return ctx->cert;
}

STACK_OF(X509) *
X509_STORE_CTX_get0_untrusted(X509_STORE_CTX *ctx)
{
  return ctx->untrusted;
}

void
X509_STORE_CTX_set0_untrusted(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
  ctx->untrusted = sk;
}

void
X509_STORE_CTX_set0_verified_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
  sk_X509_pop_free(ctx->chain, X509_free);
  ctx->chain = sk;
}

X509_POLICY_TREE *
X509_STORE_CTX_get0_policy_tree(X509_STORE_CTX *ctx)
{
  return ctx->tree;
}

int
X509_STORE_CTX_get_explicit_policy(X509_STORE_CTX *ctx)
{
  return ctx->explicit_policy;
}

int
X509_STORE_CTX_get_num_untrusted(X509_STORE_CTX *ctx)
{
  return ctx->num_untrusted;
}

int
X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name)
{
  const X509_VERIFY_PARAM *param;
  param = X509_VERIFY_PARAM_lookup(name);
  if (!param)
    return 0;
  return X509_VERIFY_PARAM_inherit(ctx->param, param);
}

X509_VERIFY_PARAM *
X509_STORE_CTX_get0_param(X509_STORE_CTX *ctx)
{
  return ctx->param;
}

void
X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param)
{
  if (ctx->param)
    X509_VERIFY_PARAM_free(ctx->param);
  ctx->param = param;
}

/*
 * Check if |bits| are adequate for |security level|.
 * Returns 1 if ok, 0 otherwise.
 */
static int
enough_bits_for_security_level(int bits, int level)
{
  /*
   * Sigh. OpenSSL does this silly squashing, so we will
   * too. Derp for Derp compatibility being important.
   */
  if (level < 0)
    level = 0;
  if (level > 5)
    level = 5;

  switch (level) {
  case 0:
    return 1;
  case 1:
    return bits >= 80;
  case 2:
    return bits >= 112;
  case 3:
    return bits >= 128;
  case 4:
    return bits >= 192;
  case 5:
    return bits >= 256;
  default:
    return 0;
  }
}

/*
 * Check whether the public key of |cert| meets the security level of |ctx|.
 *
 * Returns 1 on success, 0 otherwise.
 */
static int
check_key_level(X509_STORE_CTX *ctx, X509 *cert)
{
  EVP_PKEY *pkey;
  int bits;

  /* Unsupported or malformed keys are not secure */
  if ((pkey = X509_get0_pubkey(cert)) == NULL)
    return 0;

  if ((bits = EVP_PKEY_security_bits(pkey)) <= 0)
    return 0;

  return enough_bits_for_security_level(bits, ctx->param->security_level);
}

/*
 * Check whether the signature digest algorithm of |cert| meets the security
 * level of |ctx|.  Do not check trust anchors (self-signed or not).
 *
 * Returns 1 on success, 0 otherwise.
 */
static int
check_sig_level(X509_STORE_CTX *ctx, X509 *cert)
{
  const EVP_MD *md;
  int bits, nid, md_nid;

  if ((nid = X509_get_signature_nid(cert)) == NID_undef)
    return 0;

  /*
   * Look up signature algorithm digest.
   */

  if (!OBJ_find_sigid_algs(nid, &md_nid, NULL))
    return 0;

  if (md_nid == NID_undef)
    return 0;

  if ((md = EVP_get_digestbynid(md_nid)) == NULL)
    return 0;

  /* Assume 4 bits of collision resistance for each hash octet. */
  bits = EVP_MD_size(md) * 4;

  return enough_bits_for_security_level(bits, ctx->param->security_level);
}

int
x509_vfy_check_security_level(X509_STORE_CTX *ctx)
{
  int num = sk_X509_num(ctx->chain);
  int i;

  if (ctx->param->security_level <= 0)
    return 1;

  for (i = 0; i < num; i++) {
    X509 *cert = sk_X509_value(ctx->chain, i);

    /*
     * We've already checked the security of the leaf key, so here
     * we only check the security of issuer keys.
     */
    if (i > 0) {
      if (!check_key_level(ctx, cert) &&
          !verify_cb_cert(ctx, cert, i,
          X509_V_ERR_CA_KEY_TOO_SMALL))
        return 0;
    }

    /*
     * We also check the signature algorithm security of all certs
     * except those of the trust anchor at index num - 1.
     */
    if (i == num - 1)
      break;

    if (!check_sig_level(ctx, cert) &&
        !verify_cb_cert(ctx, cert, i, X509_V_ERR_CA_MD_TOO_WEAK))
      return 0;
  }
  return 1;
}

Coverage Report

Created: 2022-08-24 06:31