Moved CRL/OCSP checking to a dedicated plugin called revocation
This commit is contained in:
Martin Willi
@@ -0,0 +1,582 @@
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/*
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* Copyright (C) 2010 Martin Willi
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* Copyright (C) 2010 revosec AG
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* Copyright (C) 2009 Andreas Steffen
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* Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include "revocation_validator.h"
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#include <debug.h>
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#include <credentials/certificates/x509.h>
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#include <credentials/certificates/crl.h>
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#include <credentials/certificates/ocsp_request.h>
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#include <credentials/certificates/ocsp_response.h>
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#include <credentials/sets/ocsp_response_wrapper.h>
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#include <selectors/traffic_selector.h>
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typedef struct private_revocation_validator_t private_revocation_validator_t;
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/**
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* Private data of an revocation_validator_t object.
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*/
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struct private_revocation_validator_t {
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/**
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* Public revocation_validator_t interface.
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*/
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revocation_validator_t public;
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};
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/**
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* Do an OCSP request
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*/
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static certificate_t *fetch_ocsp(char *url, certificate_t *subject,
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certificate_t *issuer)
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{
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certificate_t *request, *response;
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chunk_t send, receive;
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/* TODO: requestor name, signature */
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request = lib->creds->create(lib->creds,
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CRED_CERTIFICATE, CERT_X509_OCSP_REQUEST,
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BUILD_CA_CERT, issuer,
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BUILD_CERT, subject, BUILD_END);
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if (!request)
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{
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DBG1(DBG_CFG, "generating ocsp request failed");
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return NULL;
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}
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send = request->get_encoding(request);
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request->destroy(request);
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DBG1(DBG_CFG, " requesting ocsp status from '%s' ...", url);
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if (lib->fetcher->fetch(lib->fetcher, url, &receive,
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FETCH_REQUEST_DATA, send,
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FETCH_REQUEST_TYPE, "application/ocsp-request",
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FETCH_END) != SUCCESS)
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{
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DBG1(DBG_CFG, "ocsp request to %s failed", url);
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chunk_free(&send);
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return NULL;
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}
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chunk_free(&send);
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response = lib->creds->create(lib->creds,
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CRED_CERTIFICATE, CERT_X509_OCSP_RESPONSE,
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BUILD_BLOB_ASN1_DER, receive, BUILD_END);
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chunk_free(&receive);
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if (!response)
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{
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DBG1(DBG_CFG, "parsing ocsp response failed");
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return NULL;
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}
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return response;
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}
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/**
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* check the signature of an OCSP response
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*/
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static bool verify_ocsp(ocsp_response_t *response)
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{
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certificate_t *issuer, *subject;
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identification_t *responder;
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ocsp_response_wrapper_t *wrapper;
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enumerator_t *enumerator;
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bool verified = FALSE;
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wrapper = ocsp_response_wrapper_create((ocsp_response_t*)response);
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lib->credmgr->add_local_set(lib->credmgr, &wrapper->set);
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subject = &response->certificate;
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responder = subject->get_issuer(subject);
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enumerator = lib->credmgr->create_trusted_enumerator(lib->credmgr,
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KEY_ANY, responder, FALSE);
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while (enumerator->enumerate(enumerator, &issuer, NULL))
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{
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if (lib->credmgr->issued_by(lib->credmgr, subject, issuer))
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{
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DBG1(DBG_CFG, " ocsp response correctly signed by \"%Y\"",
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issuer->get_subject(issuer));
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verified = TRUE;
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break;
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}
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}
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enumerator->destroy(enumerator);
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lib->credmgr->remove_local_set(lib->credmgr, &wrapper->set);
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wrapper->destroy(wrapper);
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return verified;
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}
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/**
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* Get the better of two OCSP responses, and check for usable OCSP info
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*/
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static certificate_t *get_better_ocsp(certificate_t *cand, certificate_t *best,
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x509_t *subject, x509_t *issuer, cert_validation_t *valid, bool cache)
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{
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ocsp_response_t *response;
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time_t revocation, this_update, next_update, valid_until;
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crl_reason_t reason;
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bool revoked = FALSE;
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response = (ocsp_response_t*)cand;
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/* check ocsp signature */
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if (!verify_ocsp(response))
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{
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DBG1(DBG_CFG, "ocsp response verification failed");
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cand->destroy(cand);
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return best;
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}
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/* check if response contains our certificate */
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switch (response->get_status(response, subject, issuer, &revocation, &reason,
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&this_update, &next_update))
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{
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case VALIDATION_REVOKED:
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/* subject has been revoked by a valid OCSP response */
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DBG1(DBG_CFG, "certificate was revoked on %T, reason: %N",
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&revocation, TRUE, crl_reason_names, reason);
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revoked = TRUE;
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break;
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case VALIDATION_GOOD:
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/* results in either good or stale */
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break;
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default:
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case VALIDATION_FAILED:
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/* candidate unusable, does not contain our cert */
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DBG1(DBG_CFG, " ocsp response contains no status on our certificate");
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cand->destroy(cand);
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return best;
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}
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/* select the better of the two responses */
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if (best == NULL || certificate_is_newer(cand, best))
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{
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DESTROY_IF(best);
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best = cand;
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if (best->get_validity(best, NULL, NULL, &valid_until))
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{
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DBG1(DBG_CFG, " ocsp response is valid: until %T",
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&valid_until, FALSE);
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*valid = VALIDATION_GOOD;
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if (cache)
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{ /* cache non-stale only, stale certs get refetched */
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lib->credmgr->cache_cert(lib->credmgr, best);
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}
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}
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else
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{
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DBG1(DBG_CFG, " ocsp response is stale: since %T",
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&valid_until, FALSE);
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*valid = VALIDATION_STALE;
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}
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}
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else
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{
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*valid = VALIDATION_STALE;
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cand->destroy(cand);
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}
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if (revoked)
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{ /* revoked always counts, even if stale */
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*valid = VALIDATION_REVOKED;
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}
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return best;
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}
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/**
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* validate a x509 certificate using OCSP
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*/
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static cert_validation_t check_ocsp(x509_t *subject, x509_t *issuer,
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auth_cfg_t *auth)
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{
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enumerator_t *enumerator;
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cert_validation_t valid = VALIDATION_SKIPPED;
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certificate_t *best = NULL, *current;
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identification_t *keyid = NULL;
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public_key_t *public;
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chunk_t chunk;
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char *uri = NULL;
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/** lookup cache for valid OCSP responses */
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enumerator = lib->credmgr->create_cert_enumerator(lib->credmgr,
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CERT_X509_OCSP_RESPONSE, KEY_ANY, NULL, FALSE);
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while (enumerator->enumerate(enumerator, ¤t))
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{
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current->get_ref(current);
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best = get_better_ocsp(current, best, subject, issuer, &valid, FALSE);
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if (best && valid != VALIDATION_STALE)
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{
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DBG1(DBG_CFG, " using cached ocsp response");
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break;
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}
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}
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enumerator->destroy(enumerator);
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/* derive the authorityKeyIdentifier from the issuer's public key */
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current = &issuer->interface;
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public = current->get_public_key(current);
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if (public && public->get_fingerprint(public, KEY_ID_PUBKEY_SHA1, &chunk))
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{
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keyid = identification_create_from_encoding(ID_KEY_ID, chunk);
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}
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/** fetch from configured OCSP responder URLs */
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if (keyid && valid != VALIDATION_GOOD && valid != VALIDATION_REVOKED)
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{
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enumerator = lib->credmgr->create_cdp_enumerator(lib->credmgr,
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CERT_X509_OCSP_RESPONSE, keyid);
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while (enumerator->enumerate(enumerator, &uri))
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{
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current = fetch_ocsp(uri, &subject->interface, &issuer->interface);
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if (current)
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{
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best = get_better_ocsp(current, best, subject, issuer,
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&valid, TRUE);
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if (best && valid != VALIDATION_STALE)
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{
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break;
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}
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}
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}
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enumerator->destroy(enumerator);
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}
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DESTROY_IF(public);
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DESTROY_IF(keyid);
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/* fallback to URL fetching from subject certificate's URIs */
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if (valid != VALIDATION_GOOD && valid != VALIDATION_REVOKED)
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{
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enumerator = subject->create_ocsp_uri_enumerator(subject);
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while (enumerator->enumerate(enumerator, &uri))
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{
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current = fetch_ocsp(uri, &subject->interface, &issuer->interface);
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if (current)
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{
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best = get_better_ocsp(current, best, subject, issuer,
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&valid, TRUE);
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if (best && valid != VALIDATION_STALE)
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{
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break;
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}
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}
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}
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enumerator->destroy(enumerator);
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}
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/* an uri was found, but no result. switch validation state to failed */
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if (valid == VALIDATION_SKIPPED && uri)
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{
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valid = VALIDATION_FAILED;
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}
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if (auth)
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{
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auth->add(auth, AUTH_RULE_OCSP_VALIDATION, valid);
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if (valid == VALIDATION_GOOD)
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{ /* successful OCSP check fulfills also CRL constraint */
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auth->add(auth, AUTH_RULE_CRL_VALIDATION, VALIDATION_GOOD);
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}
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}
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DESTROY_IF(best);
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return valid;
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}
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/**
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* fetch a CRL from an URL
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*/
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static certificate_t* fetch_crl(char *url)
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{
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certificate_t *crl;
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chunk_t chunk;
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DBG1(DBG_CFG, " fetching crl from '%s' ...", url);
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if (lib->fetcher->fetch(lib->fetcher, url, &chunk, FETCH_END) != SUCCESS)
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{
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DBG1(DBG_CFG, "crl fetching failed");
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return NULL;
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}
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crl = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509_CRL,
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BUILD_BLOB_ASN1_DER, chunk, BUILD_END);
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chunk_free(&chunk);
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if (!crl)
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{
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DBG1(DBG_CFG, "crl fetched successfully but parsing failed");
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return NULL;
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}
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return crl;
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}
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/**
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* check the signature of an CRL
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*/
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static bool verify_crl(certificate_t *crl)
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{
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certificate_t *issuer;
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enumerator_t *enumerator;
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bool verified = FALSE;
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enumerator = lib->credmgr->create_trusted_enumerator(lib->credmgr,
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KEY_ANY, crl->get_issuer(crl), FALSE);
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while (enumerator->enumerate(enumerator, &issuer, NULL))
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{
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if (lib->credmgr->issued_by(lib->credmgr, crl, issuer))
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{
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DBG1(DBG_CFG, " crl correctly signed by \"%Y\"",
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issuer->get_subject(issuer));
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verified = TRUE;
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break;
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}
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}
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enumerator->destroy(enumerator);
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return verified;
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}
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/**
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* Get the better of two CRLs, and check for usable CRL info
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*/
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static certificate_t *get_better_crl(certificate_t *cand, certificate_t *best,
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x509_t *subject, x509_t *issuer, cert_validation_t *valid, bool cache)
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{
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enumerator_t *enumerator;
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time_t revocation, valid_until;
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crl_reason_t reason;
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chunk_t serial;
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crl_t *crl;
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/* check CRL signature */
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if (!verify_crl(cand))
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{
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DBG1(DBG_CFG, "crl response verification failed");
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cand->destroy(cand);
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return best;
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}
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crl = (crl_t*)cand;
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enumerator = crl->create_enumerator(crl);
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while (enumerator->enumerate(enumerator, &serial, &revocation, &reason))
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{
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if (chunk_equals(serial, subject->get_serial(subject)))
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{
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DBG1(DBG_CFG, "certificate was revoked on %T, reason: %N",
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&revocation, TRUE, crl_reason_names, reason);
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*valid = VALIDATION_REVOKED;
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enumerator->destroy(enumerator);
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DESTROY_IF(best);
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return cand;
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}
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}
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enumerator->destroy(enumerator);
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/* select the better of the two CRLs */
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if (best == NULL || crl_is_newer(crl, (crl_t*)best))
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{
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DESTROY_IF(best);
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best = cand;
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if (best->get_validity(best, NULL, NULL, &valid_until))
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{
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DBG1(DBG_CFG, " crl is valid: until %T", &valid_until, FALSE);
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*valid = VALIDATION_GOOD;
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if (cache)
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{ /* we cache non-stale crls only, as a stale crls are refetched */
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lib->credmgr->cache_cert(lib->credmgr, best);
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}
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}
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else
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{
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DBG1(DBG_CFG, " crl is stale: since %T", &valid_until, FALSE);
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*valid = VALIDATION_STALE;
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}
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}
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else
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{
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*valid = VALIDATION_STALE;
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cand->destroy(cand);
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}
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return best;
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}
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/**
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* validate a x509 certificate using CRL
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*/
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static cert_validation_t check_crl(x509_t *subject, x509_t *issuer,
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auth_cfg_t *auth)
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{
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cert_validation_t valid = VALIDATION_SKIPPED;
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identification_t *keyid = NULL;
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certificate_t *best = NULL;
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certificate_t *current;
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public_key_t *public;
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enumerator_t *enumerator;
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chunk_t chunk;
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char *uri = NULL;
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/* derive the authorityKeyIdentifier from the issuer's public key */
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current = &issuer->interface;
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public = current->get_public_key(current);
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if (public && public->get_fingerprint(public, KEY_ID_PUBKEY_SHA1, &chunk))
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{
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keyid = identification_create_from_encoding(ID_KEY_ID, chunk);
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/* find a cached crl by authorityKeyIdentifier */
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enumerator = lib->credmgr->create_cert_enumerator(lib->credmgr,
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CERT_X509_CRL, KEY_ANY, keyid, FALSE);
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while (enumerator->enumerate(enumerator, ¤t))
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{
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current->get_ref(current);
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best = get_better_crl(current, best, subject, issuer,
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&valid, FALSE);
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if (best && valid != VALIDATION_STALE)
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{
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DBG1(DBG_CFG, " using cached crl");
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break;
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}
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}
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enumerator->destroy(enumerator);
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/* fallback to fetching crls from credential sets cdps */
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if (valid != VALIDATION_GOOD && valid != VALIDATION_REVOKED)
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{
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enumerator = lib->credmgr->create_cdp_enumerator(lib->credmgr,
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CERT_X509_CRL, keyid);
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while (enumerator->enumerate(enumerator, &uri))
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{
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current = fetch_crl(uri);
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if (current)
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{
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best = get_better_crl(current, best, subject, issuer,
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&valid, TRUE);
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if (best && valid != VALIDATION_STALE)
|
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{
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break;
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||||
}
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||||
}
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||||
}
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enumerator->destroy(enumerator);
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}
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keyid->destroy(keyid);
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}
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DESTROY_IF(public);
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/* fallback to fetching crls from cdps from subject's certificate */
|
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if (valid != VALIDATION_GOOD && valid != VALIDATION_REVOKED)
|
||||
{
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enumerator = subject->create_crl_uri_enumerator(subject);
|
||||
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while (enumerator->enumerate(enumerator, &uri))
|
||||
{
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||||
current = fetch_crl(uri);
|
||||
if (current)
|
||||
{
|
||||
best = get_better_crl(current, best, subject, issuer,
|
||||
&valid, TRUE);
|
||||
if (best && valid != VALIDATION_STALE)
|
||||
{
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
enumerator->destroy(enumerator);
|
||||
}
|
||||
|
||||
/* an uri was found, but no result. switch validation state to failed */
|
||||
if (valid == VALIDATION_SKIPPED && uri)
|
||||
{
|
||||
valid = VALIDATION_FAILED;
|
||||
}
|
||||
if (auth)
|
||||
{
|
||||
if (valid == VALIDATION_SKIPPED)
|
||||
{ /* if we skipped CRL validation, we use the result of OCSP for
|
||||
* constraint checking */
|
||||
auth->add(auth, AUTH_RULE_CRL_VALIDATION,
|
||||
auth->get(auth, AUTH_RULE_OCSP_VALIDATION));
|
||||
}
|
||||
else
|
||||
{
|
||||
auth->add(auth, AUTH_RULE_CRL_VALIDATION, valid);
|
||||
}
|
||||
}
|
||||
DESTROY_IF(best);
|
||||
return valid;
|
||||
}
|
||||
|
||||
METHOD(cert_validator_t, validate, bool,
|
||||
private_revocation_validator_t *this, certificate_t *subject,
|
||||
certificate_t *issuer, bool online, int pathlen, auth_cfg_t *auth)
|
||||
{
|
||||
if (subject->get_type(subject) == CERT_X509 &&
|
||||
issuer->get_type(issuer) == CERT_X509 &&
|
||||
online)
|
||||
{
|
||||
DBG1(DBG_CFG, "checking certificate status of \"%Y\"",
|
||||
subject->get_subject(subject));
|
||||
switch (check_ocsp((x509_t*)subject, (x509_t*)issuer, auth))
|
||||
{
|
||||
case VALIDATION_GOOD:
|
||||
DBG1(DBG_CFG, "certificate status is good");
|
||||
return TRUE;
|
||||
case VALIDATION_REVOKED:
|
||||
/* has already been logged */
|
||||
return FALSE;
|
||||
case VALIDATION_SKIPPED:
|
||||
DBG2(DBG_CFG, "ocsp check skipped, no ocsp found");
|
||||
break;
|
||||
case VALIDATION_STALE:
|
||||
DBG1(DBG_CFG, "ocsp information stale, fallback to crl");
|
||||
break;
|
||||
case VALIDATION_FAILED:
|
||||
DBG1(DBG_CFG, "ocsp check failed, fallback to crl");
|
||||
break;
|
||||
}
|
||||
switch (check_crl((x509_t*)subject, (x509_t*)issuer, auth))
|
||||
{
|
||||
case VALIDATION_GOOD:
|
||||
DBG1(DBG_CFG, "certificate status is good");
|
||||
return TRUE;
|
||||
case VALIDATION_REVOKED:
|
||||
/* has already been logged */
|
||||
return FALSE;
|
||||
case VALIDATION_FAILED:
|
||||
case VALIDATION_SKIPPED:
|
||||
DBG1(DBG_CFG, "certificate status is not available");
|
||||
break;
|
||||
case VALIDATION_STALE:
|
||||
DBG1(DBG_CFG, "certificate status is unknown, crl is stale");
|
||||
break;
|
||||
}
|
||||
}
|
||||
return TRUE;
|
||||
}
|
||||
|
||||
METHOD(revocation_validator_t, destroy, void,
|
||||
private_revocation_validator_t *this)
|
||||
{
|
||||
free(this);
|
||||
}
|
||||
|
||||
/**
|
||||
* See header
|
||||
*/
|
||||
revocation_validator_t *revocation_validator_create()
|
||||
{
|
||||
private_revocation_validator_t *this;
|
||||
|
||||
INIT(this,
|
||||
.public = {
|
||||
.validator.validate = _validate,
|
||||
.destroy = _destroy,
|
||||
},
|
||||
);
|
||||
|
||||
return &this->public;
|
||||
}
|
||||
Reference in New Issue
Block a user