ocsp_vfy.c
/*
* Copyright 2001-2022 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 <string.h>
#include <openssl/ocsp.h>
#include <openssl/err.h>
#include "internal/sizes.h"
#include "ocsp_local.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_X509_LIB);
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; 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);
ret = X509_verify_cert(ctx);
if (ret <= 0) {
int err = 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(err));
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, signer->libctx, signer->propq);
else
ret = OCSP_BASICRESP_verify(bs, skey, signer->libctx, signer->propq);
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;
}
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:
OSSL_STACK_OF_X509_free(chain);
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, r;
unsigned char tmphash[SHA_DIGEST_LENGTH], *keyhash;
EVP_MD *md;
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++) {
if ((x = sk_X509_value(certs, i)) != NULL) {
if ((md = EVP_MD_fetch(x->libctx, SN_sha1, x->propq)) == NULL)
break;
r = X509_pubkey_digest(x, md, tmphash, NULL);
EVP_MD_free(md);
if (!r)
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)
{
int ret = -1;
EVP_MD *dgst = NULL;
/* If only one ID to match then do it */
if (cid != NULL) {
char name[OSSL_MAX_NAME_SIZE];
const X509_NAME *iname;
int mdlen;
unsigned char md[EVP_MAX_MD_SIZE];
OBJ_obj2txt(name, sizeof(name), cid->hashAlgorithm.algorithm, 0);
(void)ERR_set_mark();
dgst = EVP_MD_fetch(NULL, name, NULL);
if (dgst == NULL)
dgst = (EVP_MD *)EVP_get_digestbyname(name);
if (dgst == NULL) {
(void)ERR_clear_last_mark();
ERR_raise(ERR_LIB_OCSP, OCSP_R_UNKNOWN_MESSAGE_DIGEST);
goto end;
}
(void)ERR_pop_to_mark();
mdlen = EVP_MD_get_size(dgst);
if (mdlen < 0) {
ERR_raise(ERR_LIB_OCSP, OCSP_R_DIGEST_SIZE_ERR);
goto end;
}
if (cid->issuerNameHash.length != mdlen ||
cid->issuerKeyHash.length != mdlen) {
ret = 0;
goto end;
}
iname = X509_get_subject_name(cert);
if (!X509_NAME_digest(iname, dgst, md, NULL))
goto end;
if (memcmp(md, cid->issuerNameHash.data, mdlen) != 0) {
ret = 0;
goto end;
}
if (!X509_pubkey_digest(cert, dgst, md, NULL)) {
ERR_raise(ERR_LIB_OCSP, OCSP_R_DIGEST_ERR);
goto end;
}
ret = memcmp(md, cid->issuerKeyHash.data, mdlen) == 0;
goto end;
} else {
/* We have to match the whole lot */
int i;
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;
end:
EVP_MD_free(dgst);
return ret;
}
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;
}
