ocsp_vfy.c

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/* ocsp_vfy.c */
/* Written by Dr Stephen N Henson ([email protected]) 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
 *    [email protected].
 *
 * 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
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * ([email protected]).  This product includes software written by Tim
 * Hudson ([email protected]).
 *
 */

#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 (mdlen < 0)
            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))
            return -1;
        if (memcmp(md, cid->issuerNameHash->data, mdlen))
            return 0;
        X509_pubkey_digest(cert, dgst, 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;
    }