/*

 * Copyright 2001-2016 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (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,

                                X509_NAME *nm, STACK_OF(X509) *certs,

                                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;

    STACK_OF(X509) *untrusted = NULL;

    X509_STORE_CTX *ctx = NULL;

    int i, ret = ocsp_find_signer(&signer, bs, certs, flags);

    if (!ret) {

        OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,

                OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);

        goto end;

    }

    ctx = X509_STORE_CTX_new();

    if (ctx == NULL) {

        OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_MALLOC_FAILURE);

        goto f_err;

    }

    if ((ret == 2) && (flags & OCSP_TRUSTOTHER))

        flags |= OCSP_NOVERIFY;

    if (!(flags & OCSP_NOSIGS)) {

        EVP_PKEY *skey;

        skey = X509_get0_pubkey(signer);

        if (skey == NULL) {

            OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_NO_SIGNER_KEY);

            goto err;

        }

        ret = OCSP_BASICRESP_verify(bs, skey, 0);

        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) {

            untrusted = NULL;

        } else if (bs->certs && certs) {

            untrusted = sk_X509_dup(bs->certs);

            for (i = 0; i < sk_X509_num(certs); i++) {

                if (!sk_X509_push(untrusted, sk_X509_value(certs, i))) {

                    OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_MALLOC_FAILURE);

                    goto f_err;

                }

            }

        } else if (certs != NULL) {

            untrusted = certs;

        } else {

            untrusted = bs->certs;

        }

        init_res = X509_STORE_CTX_init(ctx, st, signer, untrusted);

        if (!init_res) {

            OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_X509_LIB);

            goto f_err;

        }

        X509_STORE_CTX_set_purpose(ctx, X509_PURPOSE_OCSP_HELPER);

        ret = X509_verify_cert(ctx);

        chain = X509_STORE_CTX_get1_chain(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);

        /* 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 err;

        }

        ret = 1;

    }

 end:

    X509_STORE_CTX_free(ctx);

    sk_X509_pop_free(chain, X509_free);

    if (bs->certs && certs)

        sk_X509_free(untrusted);

    return ret;

 err:

    ret = 0;

    goto end;

 f_err:

    ret = -1;

    goto end;

}

int OCSP_resp_get0_signer(OCSP_BASICRESP *bs, X509 **signer,

                          STACK_OF(X509) *extra_certs)

{

    int ret;

    ret = ocsp_find_signer(signer, bs, extra_certs, 0);

    return (ret > 0) ? 1 : 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))) {

        *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)

{

    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))

                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 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;

}

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))

                == NULL) {

            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)

{

    if ((X509_get_extension_flags(x) & EXFLAG_XKUSAGE)

        && (X509_get_extended_key_usage(x) & 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 = 0;

    X509_STORE_CTX *ctx = X509_STORE_CTX_new();

    if (ctx == NULL) {

        OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, ERR_R_MALLOC_FAILURE);

        goto err;

    }

    if (!req->optionalSignature) {

        OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_REQUEST_NOT_SIGNED);

        goto err;

    }

    gen = req->tbsRequest.requestorName;

    if (!gen || gen->type != GEN_DIRNAME) {

        OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,

                OCSP_R_UNSUPPORTED_REQUESTORNAME_TYPE);

        goto err;

    }

    nm = gen->d.directoryName;

    ret = ocsp_req_find_signer(&signer, req, nm, certs, flags);

    if (ret <= 0) {

        OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,

                OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);

        goto err;

    }

    if ((ret == 2) && (flags & OCSP_TRUSTOTHER))

        flags |= OCSP_NOVERIFY;

    if (!(flags & OCSP_NOSIGS)) {

        EVP_PKEY *skey;

        skey = X509_get0_pubkey(signer);

        ret = OCSP_REQUEST_verify(req, skey);

        if (ret <= 0) {

            OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_SIGNATURE_FAILURE);

            goto err;

        }

    }

    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);

            goto err;

        }

        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);

        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));

            goto err;

        }

    }

    ret = 1;

    goto end;

err:

    ret = 0;

end:

    X509_STORE_CTX_free(ctx);

    return ret;

}

static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req,

                                X509_NAME *nm, STACK_OF(X509) *certs,

                                unsigned long flags)

{

    X509 *signer;

    if (!(flags & OCSP_NOINTERN)) {

        signer = X509_find_by_subject(req->optionalSignature->certs, nm);

        if (signer) {

            *psigner = signer;

            return 1;

        }

    }

    signer = X509_find_by_subject(certs, nm);

    if (signer) {

        *psigner = signer;

        return 2;

    }

    return 0;

}