text: /*
   * Copyright 2001-2021 The OpenSSL Project Authors. All Rights Reserved.
   *
   * Licensed under the Apache License 2.0 (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  #include <openssl/ocsp.h>
  #include "ocsp_local.h"
  #include <openssl/err.h>
  #include <string.h>
  
  static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs,
                              STACK_OF(X509) *certs, 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);
  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);
  static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req,
                                  const X509_NAME *nm, STACK_OF(X509) *certs,
                                  unsigned long flags);
  
  /* Returns 1 on success, 0 on failure, or -1 on fatal error */
  static int ocsp_verify_signer(X509 *signer, int response,
                                X509_STORE *st, unsigned long flags,
                                STACK_OF(X509) *untrusted, STACK_OF(X509) **chain)
  {
      X509_STORE_CTX *ctx = X509_STORE_CTX_new();
      X509_VERIFY_PARAM *vp;
      int ret = -1;
  
      if (ctx == NULL) {
          ERR_raise(ERR_LIB_OCSP, ERR_R_MALLOC_FAILURE);
          goto end;
      }
      if (!X509_STORE_CTX_init(ctx, st, signer, untrusted)) {
          ERR_raise(ERR_LIB_OCSP, ERR_R_X509_LIB);
          goto end;
      }
      if ((vp = X509_STORE_CTX_get0_param(ctx)) == NULL)
          goto end;
      if ((flags & OCSP_PARTIAL_CHAIN) != 0)
          X509_VERIFY_PARAM_set_flags(vp, X509_V_FLAG_PARTIAL_CHAIN);
      if (response
              && X509_get_ext_by_NID(signer, NID_id_pkix_OCSP_noCheck, -1) >= 0)
          /*
           * Locally disable revocation status checking for OCSP responder cert.
           * Done here for CRLs; TODO should be done also for OCSP-based checks.
           */
          X509_VERIFY_PARAM_clear_flags(vp, X509_V_FLAG_CRL_CHECK);
      X509_STORE_CTX_set_purpose(ctx, X509_PURPOSE_OCSP_HELPER);
      X509_STORE_CTX_set_trust(ctx, X509_TRUST_OCSP_REQUEST);
      /* TODO: why is X509_TRUST_OCSP_REQUEST set? Seems to get ignored. */
  
      ret = X509_verify_cert(ctx);
      if (ret <= 0) {
          ret = X509_STORE_CTX_get_error(ctx);
          ERR_raise_data(ERR_LIB_OCSP, OCSP_R_CERTIFICATE_VERIFY_ERROR,
                         "Verify error: %s", X509_verify_cert_error_string(ret));
          goto end;
      }
      if (chain != NULL)
          *chain = X509_STORE_CTX_get1_chain(ctx);
  
   end:
      X509_STORE_CTX_free(ctx);
      return ret;
  }
  
  static int ocsp_verify(OCSP_REQUEST *req, OCSP_BASICRESP *bs,
                         X509 *signer, unsigned long flags)
  {
      EVP_PKEY *skey;
      int ret = 1;
  
      if ((flags & OCSP_NOSIGS) == 0) {
          if ((skey = X509_get0_pubkey(signer)) == NULL) {
              ERR_raise(ERR_LIB_OCSP, OCSP_R_NO_SIGNER_KEY);
              return -1;
          }
          if (req != NULL)
              ret = OCSP_REQUEST_verify(req, skey);
          else
              ret = OCSP_BASICRESP_verify(bs, skey);
          if (ret <= 0)
              ERR_raise(ERR_LIB_OCSP, OCSP_R_SIGNATURE_FAILURE);
      }
      return ret;
  }
  
  /* 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;
      STACK_OF(X509) *untrusted = NULL;
      int ret = ocsp_find_signer(&signer, bs, certs, flags);
  
      if (ret == 0) {
          ERR_raise(ERR_LIB_OCSP, OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
          goto end;
      }
      if ((ret == 2) && (flags & OCSP_TRUSTOTHER) != 0)
          flags |= OCSP_NOVERIFY;
  
      if ((ret = ocsp_verify(NULL, bs, signer, flags)) <= 0)
          goto end;
      if ((flags & OCSP_NOVERIFY) == 0) {
          ret = -1;
          if ((flags & OCSP_NOCHAIN) == 0) {
              if ((untrusted = sk_X509_dup(bs->certs)) == NULL)
                  goto end;
              if (!X509_add_certs(untrusted, certs, X509_ADD_FLAG_DEFAULT))
                  goto end;
          } else if (certs != NULL) {
              untrusted = certs;
          } else {
              untrusted = bs->certs;
          }
          ret = ocsp_verify_signer(signer, 1, st, flags, untrusted, &chain);
          if (ret <= 0)
              goto end;
          if ((flags & OCSP_NOCHECKS) != 0) {
              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);
  
          /* 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) != 0)
              goto end;
  
          x = sk_X509_value(chain, sk_X509_num(chain) - 1);
          if (X509_check_trust(x, NID_OCSP_sign, 0) != X509_TRUST_TRUSTED) {
              ERR_raise(ERR_LIB_OCSP, OCSP_R_ROOT_CA_NOT_TRUSTED);
              ret = 0;
              goto end;
          }
          ret = 1;
      }
  
   end:
      sk_X509_pop_free(chain, X509_free);
      sk_X509_free(untrusted);
      return ret;
  }
  
  int OCSP_resp_get0_signer(OCSP_BASICRESP *bs, X509 **signer,
                            STACK_OF(X509) *extra_certs)
  {
      return ocsp_find_signer(signer, bs, extra_certs, 0) > 0;
  }
  
  static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs,
                              STACK_OF(X509) *certs, unsigned long flags)
  {
      X509 *signer;
      OCSP_RESPID *rid = &bs->tbsResponseData.responderId;
  
      if ((signer = ocsp_find_signer_sk(certs, rid)) != NULL) {
          *psigner = signer;
          return 2;
      }
      if ((flags & OCSP_NOINTERN) == 0 &&
          (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);
          if (!X509_pubkey_digest(x, EVP_sha1(), tmphash, NULL))
              break;
          if (memcmp(keyhash, tmphash, SHA_DIGEST_LENGTH) == 0)
              return x;
      }
      return NULL;
  }
  
  static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain)
  {
      STACK_OF(OCSP_SINGLERESP) *sresp = bs->tbsResponseData.responses;
      X509 *signer, *sca;
      OCSP_CERTID *caid = NULL;
      int ret;
  
      if (sk_X509_num(chain) <= 0) {
          ERR_raise(ERR_LIB_OCSP, OCSP_R_NO_CERTIFICATES_IN_CHAIN);
          return -1;
      }
  
      /* See if the issuer IDs match. */
      ret = ocsp_check_ids(sresp, &caid);
  
      /* If ID mismatch or other error then return */
      if (ret <= 0)
          return ret;
  
      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);
          ret = ocsp_match_issuerid(sca, caid, sresp);
          if (ret < 0)
              return ret;
          if (ret != 0) {
              /* We have a match, if extensions OK then success */
              if (ocsp_check_delegated(signer))
                  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) {
          ERR_raise(ERR_LIB_OCSP, 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 algorithm 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;
  }
  
  /*
   * Match the certificate issuer ID.
   * Returns -1 on fatal error, 0 if there is no match and 1 if there is a match.
   */
  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 != NULL) {
          const EVP_MD *dgst = EVP_get_digestbyobj(cid->hashAlgorithm.algorithm);
          const X509_NAME *iname;
          int mdlen;
          unsigned char md[EVP_MAX_MD_SIZE];
  
          if (dgst == NULL) {
              ERR_raise(ERR_LIB_OCSP, OCSP_R_UNKNOWN_MESSAGE_DIGEST);
              return -1;
          }
  
          mdlen = EVP_MD_size(dgst);
          if (mdlen < 0) {
              ERR_raise(ERR_LIB_OCSP, OCSP_R_DIGEST_SIZE_ERR);
              return -1;
          }
          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)) {
              ERR_raise(ERR_LIB_OCSP, OCSP_R_DIGEST_NAME_ERR);
              return -1;
          }
          if (memcmp(md, cid->issuerNameHash.data, mdlen) != 0)
              return 0;
          if (!X509_pubkey_digest(cert, dgst, md, NULL)) {
              ERR_raise(ERR_LIB_OCSP, OCSP_R_DIGEST_ERR);
              return -1;
          }
          if (memcmp(md, cid->issuerKeyHash.data, mdlen) != 0)
              return 0;
      } 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)
  {
      if ((X509_get_extension_flags(x) & EXFLAG_XKUSAGE)
          && (X509_get_extended_key_usage(x) & XKU_OCSP_SIGN))
          return 1;
      ERR_raise(ERR_LIB_OCSP, OCSP_R_MISSING_OCSPSIGNING_USAGE);
      return 0;
  }
  
  /*
   * Verify an OCSP request. This is much easier than OCSP response verify.
   * Just find the signer's certificate and verify it against a given trust value.
   * Returns 1 on success, 0 on failure and on fatal error.
   */
  int OCSP_request_verify(OCSP_REQUEST *req, STACK_OF(X509) *certs,
                          X509_STORE *store, unsigned long flags)
  {
      X509 *signer;
      const X509_NAME *nm;
      GENERAL_NAME *gen;
      int ret;
  
      if (!req->optionalSignature) {
          ERR_raise(ERR_LIB_OCSP, OCSP_R_REQUEST_NOT_SIGNED);
          return 0;
      }
      gen = req->tbsRequest.requestorName;
      if (!gen || gen->type != GEN_DIRNAME) {
          ERR_raise(ERR_LIB_OCSP, OCSP_R_UNSUPPORTED_REQUESTORNAME_TYPE);
          return 0; /* not returning -1 here for backward compatibility*/
      }
      nm = gen->d.directoryName;
      ret = ocsp_req_find_signer(&signer, req, nm, certs, flags);
      if (ret <= 0) {
          ERR_raise(ERR_LIB_OCSP, OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
          return 0; /* not returning -1 here for backward compatibility*/
      }
      if ((ret == 2) && (flags & OCSP_TRUSTOTHER) != 0)
          flags |= OCSP_NOVERIFY;
  
      if ((ret = ocsp_verify(req, NULL, signer, flags)) <= 0)
          return 0; /* not returning 'ret' here for backward compatibility*/
      if ((flags & OCSP_NOVERIFY) != 0)
          return 1;
      return ocsp_verify_signer(signer, 0, store, flags,
                                (flags & OCSP_NOCHAIN) != 0 ?
                                NULL : req->optionalSignature->certs, NULL) > 0;
      /* using '> 0' here to avoid breaking backward compatibility returning -1 */
  }
  
  static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req,
                                  const X509_NAME *nm, STACK_OF(X509) *certs,
                                  unsigned long flags)
  {
      X509 *signer;
  
      if ((flags & OCSP_NOINTERN) == 0) {
          signer = X509_find_by_subject(req->optionalSignature->certs, nm);
          if (signer != NULL) {
              *psigner = signer;
              return 1;
          }
      }
  
      if ((signer = X509_find_by_subject(certs, nm)) != NULL) {
          *psigner = signer;
          return 2;
      }
      return 0;
  }
  