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ocsp_vfy.c

/* ocsp_vfy.c */
/* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL
 * project 2000.
 */
/* ====================================================================
 * Copyright (c) 2000-2004 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 <openssl/ocsp.h>
#include <openssl/err.h>
#include <string.h>

static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs, STACK_OF(X509) *certs,
                        X509_STORE *st, unsigned long flags);
static X509 *ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id);
static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain, unsigned long flags);
static int ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret);
static int ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid, STACK_OF(OCSP_SINGLERESP) *sresp);
static int ocsp_check_delegated(X509 *x, int flags);
static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req, X509_NAME *nm, STACK_OF(X509) *certs,
                        X509_STORE *st, unsigned long flags);

/* Verify a basic response message */

int OCSP_basic_verify(OCSP_BASICRESP *bs, STACK_OF(X509) *certs,
                        X509_STORE *st, unsigned long flags)
      {
      X509 *signer, *x;
      STACK_OF(X509) *chain = NULL;
      X509_STORE_CTX ctx;
      int i, ret = 0;
      ret = ocsp_find_signer(&signer, bs, certs, st, flags);
      if (!ret)
            {
            OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
            goto end;
            }
      if ((ret == 2) && (flags & OCSP_TRUSTOTHER))
            flags |= OCSP_NOVERIFY;
      if (!(flags & OCSP_NOSIGS))
            {
            EVP_PKEY *skey;
            skey = X509_get_pubkey(signer);
            ret = OCSP_BASICRESP_verify(bs, skey, 0);
            EVP_PKEY_free(skey);
            if(ret <= 0)
                  {
                  OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_SIGNATURE_FAILURE);
                  goto end;
                  }
            }
      if (!(flags & OCSP_NOVERIFY))
            {
            int init_res;
            if(flags & OCSP_NOCHAIN)
                  init_res = X509_STORE_CTX_init(&ctx, st, signer, NULL);
            else
                  init_res = X509_STORE_CTX_init(&ctx, st, signer, bs->certs);
            if(!init_res)
                  {
                  OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,ERR_R_X509_LIB);
                  goto end;
                  }

            X509_STORE_CTX_set_purpose(&ctx, X509_PURPOSE_OCSP_HELPER);
            ret = X509_verify_cert(&ctx);
            chain = X509_STORE_CTX_get1_chain(&ctx);
            X509_STORE_CTX_cleanup(&ctx);
                if (ret <= 0)
                  {
                  i = X509_STORE_CTX_get_error(&ctx); 
                  OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,OCSP_R_CERTIFICATE_VERIFY_ERROR);
                  ERR_add_error_data(2, "Verify error:",
                              X509_verify_cert_error_string(i));
                        goto end;
                  }
            if(flags & OCSP_NOCHECKS)
                  {
                  ret = 1;
                  goto end;
                  }
            /* At this point we have a valid certificate chain
             * need to verify it against the OCSP issuer criteria.
             */
            ret = ocsp_check_issuer(bs, chain, flags);

            /* If fatal error or valid match then finish */
            if (ret != 0) goto end;

            /* Easy case: explicitly trusted. Get root CA and
             * check for explicit trust
             */
            if(flags & OCSP_NOEXPLICIT) goto end;

            x = sk_X509_value(chain, sk_X509_num(chain) - 1);
            if(X509_check_trust(x, NID_OCSP_sign, 0) != X509_TRUST_TRUSTED)
                  {
                  OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,OCSP_R_ROOT_CA_NOT_TRUSTED);
                  goto end;
                  }
            ret = 1;
            }



      end:
      if(chain) sk_X509_pop_free(chain, X509_free);
      return ret;
      }


static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs, STACK_OF(X509) *certs,
                        X509_STORE *st, unsigned long flags)
      {
      X509 *signer;
      OCSP_RESPID *rid = bs->tbsResponseData->responderId;
      if ((signer = ocsp_find_signer_sk(certs, rid)))
            {
            *psigner = signer;
            return 2;
            }
      if(!(flags & OCSP_NOINTERN) &&
          (signer = ocsp_find_signer_sk(bs->certs, rid)))
            {
            *psigner = signer;
            return 1;
            }
      /* Maybe lookup from store if by subject name */

      *psigner = NULL;
      return 0;
      }


static X509 *ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id)
      {
      int i;
      unsigned char tmphash[SHA_DIGEST_LENGTH], *keyhash;
      X509 *x;

      /* Easy if lookup by name */
      if (id->type == V_OCSP_RESPID_NAME)
            return X509_find_by_subject(certs, id->value.byName);

      /* Lookup by key hash */

      /* If key hash isn't SHA1 length then forget it */
      if (id->value.byKey->length != SHA_DIGEST_LENGTH) return NULL;
      keyhash = id->value.byKey->data;
      /* Calculate hash of each key and compare */
      for (i = 0; i < sk_X509_num(certs); i++)
            {
            x = sk_X509_value(certs, i);
            X509_pubkey_digest(x, EVP_sha1(), tmphash, NULL);
            if(!memcmp(keyhash, tmphash, SHA_DIGEST_LENGTH))
                  return x;
            }
      return NULL;
      }


static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain, unsigned long flags)
      {
      STACK_OF(OCSP_SINGLERESP) *sresp;
      X509 *signer, *sca;
      OCSP_CERTID *caid = NULL;
      int i;
      sresp = bs->tbsResponseData->responses;

      if (sk_X509_num(chain) <= 0)
            {
            OCSPerr(OCSP_F_OCSP_CHECK_ISSUER, OCSP_R_NO_CERTIFICATES_IN_CHAIN);
            return -1;
            }

      /* See if the issuer IDs match. */
      i = ocsp_check_ids(sresp, &caid);

      /* If ID mismatch or other error then return */
      if (i <= 0) return i;

      signer = sk_X509_value(chain, 0);
      /* Check to see if OCSP responder CA matches request CA */
      if (sk_X509_num(chain) > 1)
            {
            sca = sk_X509_value(chain, 1);
            i = ocsp_match_issuerid(sca, caid, sresp);
            if (i < 0) return i;
            if (i)
                  {
                  /* We have a match, if extensions OK then success */
                  if (ocsp_check_delegated(signer, flags)) return 1;
                  return 0;
                  }
            }

      /* Otherwise check if OCSP request signed directly by request CA */
      return ocsp_match_issuerid(signer, caid, sresp);
      }


/* Check the issuer certificate IDs for equality. If there is a mismatch with the same
 * algorithm then there's no point trying to match any certificates against the issuer.
 * If the issuer IDs all match then we just need to check equality against one of them.
 */
      
static int ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret)
      {
      OCSP_CERTID *tmpid, *cid;
      int i, idcount;

      idcount = sk_OCSP_SINGLERESP_num(sresp);
      if (idcount <= 0)
            {
            OCSPerr(OCSP_F_OCSP_CHECK_IDS, OCSP_R_RESPONSE_CONTAINS_NO_REVOCATION_DATA);
            return -1;
            }

      cid = sk_OCSP_SINGLERESP_value(sresp, 0)->certId;

      *ret = NULL;

      for (i = 1; i < idcount; i++)
            {
            tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;
            /* Check to see if IDs match */
            if (OCSP_id_issuer_cmp(cid, tmpid))
                  {
                  /* If algoritm mismatch let caller deal with it */
                  if (OBJ_cmp(tmpid->hashAlgorithm->algorithm,
                              cid->hashAlgorithm->algorithm))
                              return 2;
                  /* Else mismatch */
                  return 0;
                  }
            }

      /* All IDs match: only need to check one ID */
      *ret = cid;
      return 1;
      }


static int ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid,
                  STACK_OF(OCSP_SINGLERESP) *sresp)
      {
      /* If only one ID to match then do it */
      if(cid)
            {
            const EVP_MD *dgst;
            X509_NAME *iname;
            int mdlen;
            unsigned char md[EVP_MAX_MD_SIZE];
            if (!(dgst = EVP_get_digestbyobj(cid->hashAlgorithm->algorithm)))
                  {
                  OCSPerr(OCSP_F_OCSP_MATCH_ISSUERID, OCSP_R_UNKNOWN_MESSAGE_DIGEST);
                  return -1;
                  }

            mdlen = EVP_MD_size(dgst);
            if ((cid->issuerNameHash->length != mdlen) ||
               (cid->issuerKeyHash->length != mdlen))
                  return 0;
            iname = X509_get_subject_name(cert);
            if (!X509_NAME_digest(iname, dgst, md, NULL))
                  return -1;
            if (memcmp(md, cid->issuerNameHash->data, mdlen))
                  return 0;
            X509_pubkey_digest(cert, EVP_sha1(), md, NULL);
            if (memcmp(md, cid->issuerKeyHash->data, mdlen))
                  return 0;

            return 1;

            }
      else
            {
            /* We have to match the whole lot */
            int i, ret;
            OCSP_CERTID *tmpid;
            for (i = 0; i < sk_OCSP_SINGLERESP_num(sresp); i++)
                  {
                  tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;
                  ret = ocsp_match_issuerid(cert, tmpid, NULL);
                  if (ret <= 0) return ret;
                  }
            return 1;
            }
                  
      }

static int ocsp_check_delegated(X509 *x, int flags)
      {
      X509_check_purpose(x, -1, 0);
      if ((x->ex_flags & EXFLAG_XKUSAGE) &&
          (x->ex_xkusage & XKU_OCSP_SIGN))
            return 1;
      OCSPerr(OCSP_F_OCSP_CHECK_DELEGATED, OCSP_R_MISSING_OCSPSIGNING_USAGE);
      return 0;
      }

/* Verify an OCSP request. This is fortunately much easier than OCSP
 * response verify. Just find the signers certificate and verify it
 * against a given trust value.
 */

int OCSP_request_verify(OCSP_REQUEST *req, STACK_OF(X509) *certs, X509_STORE *store, unsigned long flags)
        {
      X509 *signer;
      X509_NAME *nm;
      GENERAL_NAME *gen;
      int ret;
      X509_STORE_CTX ctx;
      if (!req->optionalSignature) 
            {
            OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_REQUEST_NOT_SIGNED);
            return 0;
            }
      gen = req->tbsRequest->requestorName;
      if (!gen || gen->type != GEN_DIRNAME)
            {
            OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_UNSUPPORTED_REQUESTORNAME_TYPE);
            return 0;
            }
      nm = gen->d.directoryName;
      ret = ocsp_req_find_signer(&signer, req, nm, certs, store, flags);
      if (ret <= 0)
            {
            OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
            return 0;
            }
      if ((ret == 2) && (flags & OCSP_TRUSTOTHER))
            flags |= OCSP_NOVERIFY;
      if (!(flags & OCSP_NOSIGS))
            {
            EVP_PKEY *skey;
            skey = X509_get_pubkey(signer);
            ret = OCSP_REQUEST_verify(req, skey);
            EVP_PKEY_free(skey);
            if(ret <= 0)
                  {
                  OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_SIGNATURE_FAILURE);
                  return 0;
                  }
            }
      if (!(flags & OCSP_NOVERIFY))
            {
            int init_res;
            if(flags & OCSP_NOCHAIN)
                  init_res = X509_STORE_CTX_init(&ctx, store, signer, NULL);
            else
                  init_res = X509_STORE_CTX_init(&ctx, store, signer,
                              req->optionalSignature->certs);
            if(!init_res)
                  {
                  OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,ERR_R_X509_LIB);
                  return 0;
                  }

            X509_STORE_CTX_set_purpose(&ctx, X509_PURPOSE_OCSP_HELPER);
            X509_STORE_CTX_set_trust(&ctx, X509_TRUST_OCSP_REQUEST);
            ret = X509_verify_cert(&ctx);
            X509_STORE_CTX_cleanup(&ctx);
                if (ret <= 0)
                  {
                  ret = X509_STORE_CTX_get_error(&ctx);     
                  OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,OCSP_R_CERTIFICATE_VERIFY_ERROR);
                  ERR_add_error_data(2, "Verify error:",
                              X509_verify_cert_error_string(ret));
                        return 0;
                  }
            }
      return 1;
        }

static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req, X509_NAME *nm, STACK_OF(X509) *certs,
                        X509_STORE *st, unsigned long flags)
      {
      X509 *signer;
      if(!(flags & OCSP_NOINTERN))
            {
            signer = X509_find_by_subject(req->optionalSignature->certs, nm);
            *psigner = signer;
            return 1;
            }

      signer = X509_find_by_subject(certs, nm);
      if (signer)
            {
            *psigner = signer;
            return 2;
            }
      return 0;
      }

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