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|
/*
* Copyright (c) 2015 Marko Kreen <markokr@gmail.com>
* Copyright (c) 2016 Bob Beck <beck@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <openssl/err.h>
#include <openssl/ocsp.h>
#include <openssl/x509.h>
#include <tls.h>
#include "tls_internal.h"
#define MAXAGE_SEC (14*24*60*60)
#define JITTER_SEC (60)
/*
* State for request.
*/
static struct tls_ocsp *
tls_ocsp_new(void)
{
return (calloc(1, sizeof(struct tls_ocsp)));
}
void
tls_ocsp_free(struct tls_ocsp *ocsp)
{
if (ocsp == NULL)
return;
free(ocsp->ocsp_result);
ocsp->ocsp_result = NULL;
free(ocsp->ocsp_url);
ocsp->ocsp_url = NULL;
free(ocsp);
}
static int
tls_ocsp_asn1_parse_time(struct tls *ctx, ASN1_GENERALIZEDTIME *gt, time_t *gt_time)
{
struct tm tm;
if (gt == NULL)
return -1;
/* RFC 6960 specifies that all times in OCSP must be GENERALIZEDTIME */
if (ASN1_time_parse(gt->data, gt->length, &tm,
V_ASN1_GENERALIZEDTIME) == -1)
return -1;
if ((*gt_time = timegm(&tm)) == -1)
return -1;
return 0;
}
static int
tls_ocsp_fill_info(struct tls *ctx, int response_status, int cert_status,
int crl_reason, ASN1_GENERALIZEDTIME *revtime,
ASN1_GENERALIZEDTIME *thisupd, ASN1_GENERALIZEDTIME *nextupd)
{
struct tls_ocsp_result *info = NULL;
free(ctx->ocsp->ocsp_result);
ctx->ocsp->ocsp_result = NULL;
if ((info = calloc(1, sizeof (struct tls_ocsp_result))) == NULL) {
tls_set_error(ctx, "calloc");
return -1;
}
info->response_status = response_status;
info->cert_status = cert_status;
info->crl_reason = crl_reason;
if (info->response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
info->result_msg =
OCSP_response_status_str(info->response_status);
} else if (info->cert_status != V_OCSP_CERTSTATUS_REVOKED) {
info->result_msg = OCSP_cert_status_str(info->cert_status);
} else {
info->result_msg = OCSP_crl_reason_str(info->crl_reason);
}
info->revocation_time = info->this_update = info->next_update = -1;
if (revtime != NULL &&
tls_ocsp_asn1_parse_time(ctx, revtime, &info->revocation_time) != 0) {
tls_set_error(ctx,
"unable to parse revocation time in OCSP reply");
goto error;
}
if (thisupd != NULL &&
tls_ocsp_asn1_parse_time(ctx, thisupd, &info->this_update) != 0) {
tls_set_error(ctx,
"unable to parse this update time in OCSP reply");
goto error;
}
if (nextupd != NULL &&
tls_ocsp_asn1_parse_time(ctx, nextupd, &info->next_update) != 0) {
tls_set_error(ctx,
"unable to parse next update time in OCSP reply");
goto error;
}
ctx->ocsp->ocsp_result = info;
return 0;
error:
free(info);
return -1;
}
static OCSP_CERTID *
tls_ocsp_get_certid(X509 *main_cert, STACK_OF(X509) *extra_certs,
SSL_CTX *ssl_ctx)
{
X509_NAME *issuer_name;
X509 *issuer;
X509_STORE_CTX storectx;
X509_OBJECT tmpobj;
OCSP_CERTID *cid = NULL;
X509_STORE *store;
if ((issuer_name = X509_get_issuer_name(main_cert)) == NULL)
return NULL;
if (extra_certs != NULL) {
issuer = X509_find_by_subject(extra_certs, issuer_name);
if (issuer != NULL)
return OCSP_cert_to_id(NULL, main_cert, issuer);
}
if ((store = SSL_CTX_get_cert_store(ssl_ctx)) == NULL)
return NULL;
if (X509_STORE_CTX_init(&storectx, store, main_cert, extra_certs) != 1)
return NULL;
if (X509_STORE_get_by_subject(&storectx, X509_LU_X509, issuer_name,
&tmpobj) == 1) {
cid = OCSP_cert_to_id(NULL, main_cert, tmpobj.data.x509);
X509_OBJECT_free_contents(&tmpobj);
}
X509_STORE_CTX_cleanup(&storectx);
return cid;
}
struct tls_ocsp *
tls_ocsp_setup_from_peer(struct tls *ctx)
{
struct tls_ocsp *ocsp = NULL;
STACK_OF(OPENSSL_STRING) *ocsp_urls = NULL;
if ((ocsp = tls_ocsp_new()) == NULL)
goto failed;
/* steal state from ctx struct */
ocsp->main_cert = SSL_get_peer_certificate(ctx->ssl_conn);
ocsp->extra_certs = SSL_get_peer_cert_chain(ctx->ssl_conn);
if (ocsp->main_cert == NULL) {
tls_set_errorx(ctx, "no peer certificate for OCSP");
goto failed;
}
ocsp_urls = X509_get1_ocsp(ocsp->main_cert);
if (ocsp_urls == NULL)
goto failed;
ocsp->ocsp_url = strdup(sk_OPENSSL_STRING_value(ocsp_urls, 0));
if (ocsp->ocsp_url == NULL) {
tls_set_errorx(ctx, "out of memory");
goto failed;
}
X509_email_free(ocsp_urls);
return ocsp;
failed:
tls_ocsp_free(ocsp);
X509_email_free(ocsp_urls);
return NULL;
}
static int
tls_ocsp_verify_response(struct tls *ctx, OCSP_RESPONSE *resp)
{
OCSP_BASICRESP *br = NULL;
ASN1_GENERALIZEDTIME *revtime = NULL, *thisupd = NULL, *nextupd = NULL;
OCSP_CERTID *cid = NULL;
STACK_OF(X509) *combined = NULL;
int response_status=0, cert_status=0, crl_reason=0;
int ret = -1;
unsigned long flags;
if ((br = OCSP_response_get1_basic(resp)) == NULL) {
tls_set_errorx(ctx, "cannot load ocsp reply");
goto error;
}
/*
* Skip validation of 'extra_certs' as this should be done
* already as part of main handshake.
*/
flags = OCSP_TRUSTOTHER;
/* now verify */
if (OCSP_basic_verify(br, ctx->ocsp->extra_certs,
SSL_CTX_get_cert_store(ctx->ssl_ctx), flags) != 1) {
tls_set_error(ctx, "ocsp verify failed");
goto error;
}
/* signature OK, look inside */
response_status = OCSP_response_status(resp);
if (response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
tls_set_errorx(ctx, "ocsp verify failed: response - %s",
OCSP_response_status_str(response_status));
goto error;
}
cid = tls_ocsp_get_certid(ctx->ocsp->main_cert,
ctx->ocsp->extra_certs, ctx->ssl_ctx);
if (cid == NULL) {
tls_set_errorx(ctx, "ocsp verify failed: no issuer cert");
goto error;
}
if (OCSP_resp_find_status(br, cid, &cert_status, &crl_reason,
&revtime, &thisupd, &nextupd) != 1) {
tls_set_errorx(ctx, "ocsp verify failed: no result for cert");
goto error;
}
if (OCSP_check_validity(thisupd, nextupd, JITTER_SEC,
MAXAGE_SEC) != 1) {
tls_set_errorx(ctx,
"ocsp verify failed: ocsp response not current");
goto error;
}
if (tls_ocsp_fill_info(ctx, response_status, cert_status,
crl_reason, revtime, thisupd, nextupd) != 0)
goto error;
/* finally can look at status */
if (cert_status != V_OCSP_CERTSTATUS_GOOD && cert_status !=
V_OCSP_CERTSTATUS_UNKNOWN) {
tls_set_errorx(ctx, "ocsp verify failed: revoked cert - %s",
OCSP_crl_reason_str(crl_reason));
goto error;
}
ret = 0;
error:
sk_X509_free(combined);
OCSP_CERTID_free(cid);
OCSP_BASICRESP_free(br);
return ret;
}
/*
* Process a raw OCSP response from an OCSP server request.
* OCSP details can then be retrieved with tls_peer_ocsp_* functions.
* returns 0 if certificate ok, -1 otherwise.
*/
static int
tls_ocsp_process_response_internal(struct tls *ctx, const unsigned char *response,
size_t size)
{
int ret;
OCSP_RESPONSE *resp;
resp = d2i_OCSP_RESPONSE(NULL, &response, size);
if (resp == NULL) {
tls_ocsp_free(ctx->ocsp);
ctx->ocsp = NULL;
tls_set_error(ctx, "unable to parse OCSP response");
return -1;
}
ret = tls_ocsp_verify_response(ctx, resp);
OCSP_RESPONSE_free(resp);
return ret;
}
/* TLS handshake verification callback for stapled requests */
int
tls_ocsp_verify_cb(SSL *ssl, void *arg)
{
const unsigned char *raw = NULL;
int size, res = -1;
struct tls *ctx;
if ((ctx = SSL_get_app_data(ssl)) == NULL)
return -1;
size = SSL_get_tlsext_status_ocsp_resp(ssl, &raw);
if (size <= 0) {
if (ctx->config->ocsp_require_stapling) {
tls_set_errorx(ctx, "no stapled OCSP response provided");
return 0;
}
return 1;
}
tls_ocsp_free(ctx->ocsp);
ctx->ocsp = tls_ocsp_setup_from_peer(ctx);
if (ctx->ocsp != NULL) {
if (ctx->config->verify_cert == 0 || ctx->config->verify_time == 0)
return 1;
res = tls_ocsp_process_response_internal(ctx, raw, size);
}
return (res == 0) ? 1 : 0;
}
/* Staple the OCSP information in ctx->ocsp to the server handshake. */
int
tls_ocsp_stapling_cb(SSL *ssl, void *arg)
{
struct tls *ctx;
unsigned char *ocsp_staple = NULL;
int ret = SSL_TLSEXT_ERR_ALERT_FATAL;
if ((ctx = SSL_get_app_data(ssl)) == NULL)
goto err;
if (ctx->config->keypair == NULL ||
ctx->config->keypair->ocsp_staple == NULL ||
ctx->config->keypair->ocsp_staple_len == 0)
return SSL_TLSEXT_ERR_NOACK;
if ((ocsp_staple = malloc(ctx->config->keypair->ocsp_staple_len)) ==
NULL)
goto err;
memcpy(ocsp_staple, ctx->config->keypair->ocsp_staple,
ctx->config->keypair->ocsp_staple_len);
if (SSL_set_tlsext_status_ocsp_resp(ctx->ssl_conn, ocsp_staple,
ctx->config->keypair->ocsp_staple_len) != 1)
goto err;
ret = SSL_TLSEXT_ERR_OK;
err:
if (ret != SSL_TLSEXT_ERR_OK)
free(ocsp_staple);
return ret;
}
/*
* Public API
*/
/* Retrieve OCSP URL from peer certificate, if present */
const char *
tls_peer_ocsp_url(struct tls *ctx)
{
if (ctx->ocsp == NULL)
return NULL;
return ctx->ocsp->ocsp_url;
}
const char *
tls_peer_ocsp_result(struct tls *ctx)
{
if (ctx->ocsp == NULL)
return NULL;
if (ctx->ocsp->ocsp_result == NULL)
return NULL;
return ctx->ocsp->ocsp_result->result_msg;
}
int
tls_peer_ocsp_response_status(struct tls *ctx)
{
if (ctx->ocsp == NULL)
return -1;
if (ctx->ocsp->ocsp_result == NULL)
return -1;
return ctx->ocsp->ocsp_result->response_status;
}
int
tls_peer_ocsp_cert_status(struct tls *ctx)
{
if (ctx->ocsp == NULL)
return -1;
if (ctx->ocsp->ocsp_result == NULL)
return -1;
return ctx->ocsp->ocsp_result->cert_status;
}
int
tls_peer_ocsp_crl_reason(struct tls *ctx)
{
if (ctx->ocsp == NULL)
return -1;
if (ctx->ocsp->ocsp_result == NULL)
return -1;
return ctx->ocsp->ocsp_result->crl_reason;
}
time_t
tls_peer_ocsp_this_update(struct tls *ctx)
{
if (ctx->ocsp == NULL)
return -1;
if (ctx->ocsp->ocsp_result == NULL)
return -1;
return ctx->ocsp->ocsp_result->this_update;
}
time_t
tls_peer_ocsp_next_update(struct tls *ctx)
{
if (ctx->ocsp == NULL)
return -1;
if (ctx->ocsp->ocsp_result == NULL)
return -1;
return ctx->ocsp->ocsp_result->next_update;
}
time_t
tls_peer_ocsp_revocation_time(struct tls *ctx)
{
if (ctx->ocsp == NULL)
return -1;
if (ctx->ocsp->ocsp_result == NULL)
return -1;
return ctx->ocsp->ocsp_result->revocation_time;
}
int
tls_ocsp_process_response(struct tls *ctx, const unsigned char *response,
size_t size)
{
if ((ctx->state & TLS_HANDSHAKE_COMPLETE) == 0)
return -1;
return tls_ocsp_process_response_internal(ctx, response, size);
}
|