462 lines
11 KiB
C
Executable File
462 lines
11 KiB
C
Executable File
/* $OpenBSD: tls_ocsp.c,v 1.22 2021/10/31 16:39:32 tb Exp $ */
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/*
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* Copyright (c) 2015 Marko Kreen <markokr@gmail.com>
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* Copyright (c) 2016 Bob Beck <beck@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/types.h>
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#include <arpa/inet.h>
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#include <netinet/in.h>
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#include <openssl/err.h>
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#include <openssl/ocsp.h>
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#include <openssl/x509.h>
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#include <tls.h>
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#include "tls_internal.h"
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#define MAXAGE_SEC (14*24*60*60)
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#define JITTER_SEC (60)
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/*
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* State for request.
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*/
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static struct tls_ocsp *
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tls_ocsp_new(void)
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{
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return (calloc(1, sizeof(struct tls_ocsp)));
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}
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void
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tls_ocsp_free(struct tls_ocsp *ocsp)
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{
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if (ocsp == NULL)
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return;
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X509_free(ocsp->main_cert);
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free(ocsp->ocsp_result);
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free(ocsp->ocsp_url);
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free(ocsp);
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}
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static int
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tls_ocsp_asn1_parse_time(struct tls *ctx, ASN1_GENERALIZEDTIME *gt, time_t *gt_time)
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{
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struct tm tm;
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if (gt == NULL)
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return -1;
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/* RFC 6960 specifies that all times in OCSP must be GENERALIZEDTIME */
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if (ASN1_time_parse(gt->data, gt->length, &tm,
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V_ASN1_GENERALIZEDTIME) == -1)
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return -1;
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if ((*gt_time = timegm(&tm)) == -1)
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return -1;
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return 0;
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}
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static int
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tls_ocsp_fill_info(struct tls *ctx, int response_status, int cert_status,
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int crl_reason, ASN1_GENERALIZEDTIME *revtime,
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ASN1_GENERALIZEDTIME *thisupd, ASN1_GENERALIZEDTIME *nextupd)
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{
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struct tls_ocsp_result *info = NULL;
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free(ctx->ocsp->ocsp_result);
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ctx->ocsp->ocsp_result = NULL;
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if ((info = calloc(1, sizeof (struct tls_ocsp_result))) == NULL) {
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tls_set_error(ctx, "calloc");
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return -1;
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}
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info->response_status = response_status;
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info->cert_status = cert_status;
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info->crl_reason = crl_reason;
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if (info->response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
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info->result_msg =
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OCSP_response_status_str(info->response_status);
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} else if (info->cert_status != V_OCSP_CERTSTATUS_REVOKED) {
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info->result_msg = OCSP_cert_status_str(info->cert_status);
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} else {
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info->result_msg = OCSP_crl_reason_str(info->crl_reason);
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}
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info->revocation_time = info->this_update = info->next_update = -1;
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if (revtime != NULL &&
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tls_ocsp_asn1_parse_time(ctx, revtime, &info->revocation_time) != 0) {
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tls_set_error(ctx,
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"unable to parse revocation time in OCSP reply");
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goto err;
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}
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if (thisupd != NULL &&
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tls_ocsp_asn1_parse_time(ctx, thisupd, &info->this_update) != 0) {
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tls_set_error(ctx,
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"unable to parse this update time in OCSP reply");
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goto err;
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}
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if (nextupd != NULL &&
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tls_ocsp_asn1_parse_time(ctx, nextupd, &info->next_update) != 0) {
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tls_set_error(ctx,
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"unable to parse next update time in OCSP reply");
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goto err;
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}
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ctx->ocsp->ocsp_result = info;
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return 0;
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err:
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free(info);
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return -1;
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}
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static OCSP_CERTID *
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tls_ocsp_get_certid(X509 *main_cert, STACK_OF(X509) *extra_certs,
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SSL_CTX *ssl_ctx)
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{
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X509_NAME *issuer_name;
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X509 *issuer;
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X509_STORE_CTX *storectx = NULL;
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X509_OBJECT *obj = NULL;
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OCSP_CERTID *cid = NULL;
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X509_STORE *store;
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if ((issuer_name = X509_get_issuer_name(main_cert)) == NULL)
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goto out;
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if (extra_certs != NULL) {
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issuer = X509_find_by_subject(extra_certs, issuer_name);
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if (issuer != NULL) {
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cid = OCSP_cert_to_id(NULL, main_cert, issuer);
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goto out;
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}
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}
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if ((store = SSL_CTX_get_cert_store(ssl_ctx)) == NULL)
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goto out;
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if ((storectx = X509_STORE_CTX_new()) == NULL)
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goto out;
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if (X509_STORE_CTX_init(storectx, store, main_cert, extra_certs) != 1)
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goto out;
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if ((obj = X509_STORE_CTX_get_obj_by_subject(storectx, X509_LU_X509,
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issuer_name)) == NULL)
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goto out;
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cid = OCSP_cert_to_id(NULL, main_cert, X509_OBJECT_get0_X509(obj));
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out:
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X509_STORE_CTX_free(storectx);
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X509_OBJECT_free(obj);
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return cid;
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}
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struct tls_ocsp *
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tls_ocsp_setup_from_peer(struct tls *ctx)
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{
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struct tls_ocsp *ocsp = NULL;
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STACK_OF(OPENSSL_STRING) *ocsp_urls = NULL;
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if ((ocsp = tls_ocsp_new()) == NULL)
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goto err;
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/* steal state from ctx struct */
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ocsp->main_cert = SSL_get_peer_certificate(ctx->ssl_conn);
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ocsp->extra_certs = SSL_get_peer_cert_chain(ctx->ssl_conn);
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if (ocsp->main_cert == NULL) {
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tls_set_errorx(ctx, "no peer certificate for OCSP");
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goto err;
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}
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ocsp_urls = X509_get1_ocsp(ocsp->main_cert);
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if (ocsp_urls == NULL) {
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tls_set_errorx(ctx, "no OCSP URLs in peer certificate");
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goto err;
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}
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ocsp->ocsp_url = strdup(sk_OPENSSL_STRING_value(ocsp_urls, 0));
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if (ocsp->ocsp_url == NULL) {
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tls_set_errorx(ctx, "out of memory");
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goto err;
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}
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X509_email_free(ocsp_urls);
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return ocsp;
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err:
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tls_ocsp_free(ocsp);
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X509_email_free(ocsp_urls);
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return NULL;
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}
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static int
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tls_ocsp_verify_response(struct tls *ctx, OCSP_RESPONSE *resp)
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{
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OCSP_BASICRESP *br = NULL;
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ASN1_GENERALIZEDTIME *revtime = NULL, *thisupd = NULL, *nextupd = NULL;
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OCSP_CERTID *cid = NULL;
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STACK_OF(X509) *combined = NULL;
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int response_status=0, cert_status=0, crl_reason=0;
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int ret = -1;
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unsigned long flags;
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if ((br = OCSP_response_get1_basic(resp)) == NULL) {
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tls_set_errorx(ctx, "cannot load ocsp reply");
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goto err;
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}
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/*
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* Skip validation of 'extra_certs' as this should be done
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* already as part of main handshake.
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*/
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flags = OCSP_TRUSTOTHER;
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/* now verify */
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if (OCSP_basic_verify(br, ctx->ocsp->extra_certs,
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SSL_CTX_get_cert_store(ctx->ssl_ctx), flags) != 1) {
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tls_set_errorx(ctx, "ocsp verify failed");
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goto err;
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}
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/* signature OK, look inside */
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response_status = OCSP_response_status(resp);
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if (response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
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tls_set_errorx(ctx, "ocsp verify failed: response - %s",
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OCSP_response_status_str(response_status));
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goto err;
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}
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cid = tls_ocsp_get_certid(ctx->ocsp->main_cert,
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ctx->ocsp->extra_certs, ctx->ssl_ctx);
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if (cid == NULL) {
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tls_set_errorx(ctx, "ocsp verify failed: no issuer cert");
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goto err;
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}
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if (OCSP_resp_find_status(br, cid, &cert_status, &crl_reason,
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&revtime, &thisupd, &nextupd) != 1) {
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tls_set_errorx(ctx, "ocsp verify failed: no result for cert");
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goto err;
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}
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if (OCSP_check_validity(thisupd, nextupd, JITTER_SEC,
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MAXAGE_SEC) != 1) {
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tls_set_errorx(ctx,
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"ocsp verify failed: ocsp response not current");
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goto err;
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}
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if (tls_ocsp_fill_info(ctx, response_status, cert_status,
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crl_reason, revtime, thisupd, nextupd) != 0)
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goto err;
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/* finally can look at status */
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if (cert_status != V_OCSP_CERTSTATUS_GOOD && cert_status !=
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V_OCSP_CERTSTATUS_UNKNOWN) {
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tls_set_errorx(ctx, "ocsp verify failed: revoked cert - %s",
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OCSP_crl_reason_str(crl_reason));
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goto err;
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}
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ret = 0;
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err:
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sk_X509_free(combined);
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OCSP_CERTID_free(cid);
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OCSP_BASICRESP_free(br);
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return ret;
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}
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/*
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* Process a raw OCSP response from an OCSP server request.
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* OCSP details can then be retrieved with tls_peer_ocsp_* functions.
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* returns 0 if certificate ok, -1 otherwise.
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*/
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static int
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tls_ocsp_process_response_internal(struct tls *ctx, const unsigned char *response,
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size_t size)
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{
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int ret;
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OCSP_RESPONSE *resp;
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resp = d2i_OCSP_RESPONSE(NULL, &response, size);
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if (resp == NULL) {
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tls_ocsp_free(ctx->ocsp);
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ctx->ocsp = NULL;
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tls_set_error(ctx, "unable to parse OCSP response");
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return -1;
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}
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ret = tls_ocsp_verify_response(ctx, resp);
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OCSP_RESPONSE_free(resp);
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return ret;
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}
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/* TLS handshake verification callback for stapled requests */
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int
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tls_ocsp_verify_cb(SSL *ssl, void *arg)
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{
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const unsigned char *raw = NULL;
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int size, res = -1;
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struct tls *ctx;
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if ((ctx = SSL_get_app_data(ssl)) == NULL)
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return -1;
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size = SSL_get_tlsext_status_ocsp_resp(ssl, &raw);
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if (size <= 0) {
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if (ctx->config->ocsp_require_stapling) {
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tls_set_errorx(ctx, "no stapled OCSP response provided");
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return 0;
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}
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return 1;
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}
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tls_ocsp_free(ctx->ocsp);
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if ((ctx->ocsp = tls_ocsp_setup_from_peer(ctx)) == NULL)
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return 0;
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if (ctx->config->verify_cert == 0 || ctx->config->verify_time == 0)
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return 1;
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res = tls_ocsp_process_response_internal(ctx, raw, size);
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return (res == 0) ? 1 : 0;
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}
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/* Staple the OCSP information in ctx->ocsp to the server handshake. */
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int
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tls_ocsp_stapling_cb(SSL *ssl, void *arg)
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{
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int ret = SSL_TLSEXT_ERR_ALERT_FATAL;
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unsigned char *ocsp_staple = NULL;
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struct tls *ctx;
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if ((ctx = SSL_get_app_data(ssl)) == NULL)
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goto err;
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if (ctx->keypair == NULL || ctx->keypair->ocsp_staple == NULL ||
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ctx->keypair->ocsp_staple_len == 0)
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return SSL_TLSEXT_ERR_NOACK;
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if ((ocsp_staple = malloc(ctx->keypair->ocsp_staple_len)) == NULL)
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goto err;
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memcpy(ocsp_staple, ctx->keypair->ocsp_staple,
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ctx->keypair->ocsp_staple_len);
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if (SSL_set_tlsext_status_ocsp_resp(ctx->ssl_conn, ocsp_staple,
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ctx->keypair->ocsp_staple_len) != 1)
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goto err;
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ret = SSL_TLSEXT_ERR_OK;
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err:
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if (ret != SSL_TLSEXT_ERR_OK)
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free(ocsp_staple);
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return ret;
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}
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/*
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* Public API
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*/
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/* Retrieve OCSP URL from peer certificate, if present. */
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const char *
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tls_peer_ocsp_url(struct tls *ctx)
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{
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if (ctx->ocsp == NULL)
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return NULL;
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return ctx->ocsp->ocsp_url;
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}
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const char *
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tls_peer_ocsp_result(struct tls *ctx)
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{
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if (ctx->ocsp == NULL)
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return NULL;
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if (ctx->ocsp->ocsp_result == NULL)
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return NULL;
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return ctx->ocsp->ocsp_result->result_msg;
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}
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int
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tls_peer_ocsp_response_status(struct tls *ctx)
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{
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if (ctx->ocsp == NULL)
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return -1;
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if (ctx->ocsp->ocsp_result == NULL)
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return -1;
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return ctx->ocsp->ocsp_result->response_status;
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}
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int
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tls_peer_ocsp_cert_status(struct tls *ctx)
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{
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if (ctx->ocsp == NULL)
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return -1;
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if (ctx->ocsp->ocsp_result == NULL)
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return -1;
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return ctx->ocsp->ocsp_result->cert_status;
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}
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int
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tls_peer_ocsp_crl_reason(struct tls *ctx)
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{
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if (ctx->ocsp == NULL)
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return -1;
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if (ctx->ocsp->ocsp_result == NULL)
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return -1;
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return ctx->ocsp->ocsp_result->crl_reason;
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}
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time_t
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tls_peer_ocsp_this_update(struct tls *ctx)
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{
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if (ctx->ocsp == NULL)
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return -1;
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if (ctx->ocsp->ocsp_result == NULL)
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return -1;
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return ctx->ocsp->ocsp_result->this_update;
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}
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time_t
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tls_peer_ocsp_next_update(struct tls *ctx)
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{
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if (ctx->ocsp == NULL)
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return -1;
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if (ctx->ocsp->ocsp_result == NULL)
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return -1;
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return ctx->ocsp->ocsp_result->next_update;
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}
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time_t
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tls_peer_ocsp_revocation_time(struct tls *ctx)
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{
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if (ctx->ocsp == NULL)
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return -1;
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if (ctx->ocsp->ocsp_result == NULL)
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return -1;
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return ctx->ocsp->ocsp_result->revocation_time;
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}
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int
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tls_ocsp_process_response(struct tls *ctx, const unsigned char *response,
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size_t size)
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{
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if ((ctx->state & TLS_HANDSHAKE_COMPLETE) == 0)
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return -1;
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return tls_ocsp_process_response_internal(ctx, response, size);
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}
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