ssl_util_stapling.c revision 11f2c481e1d57bedb3f758565307501e9a2730dd
/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* _ _
* _ __ ___ ___ __| | ___ ___| | mod_ssl
* | '_ ` _ \ / _ \ / _` | / __/ __| | Apache Interface to OpenSSL
* | | | | | | (_) | (_| | \__ \__ \ |
* |_| |_| |_|\___/ \__,_|___|___/___/_|
* |_____|
* ssl_stapling.c
* OCSP Stapling Support
*/
/* ``Where's the spoons?
Where's the spoons?
Where's the bloody spoons?''
-- Alexei Sayle */
#include "ssl_private.h"
#include "ap_mpm.h"
#include "apr_thread_mutex.h"
#ifdef HAVE_OCSP_STAPLING
/**
* Maxiumum OCSP stapling response size. This should be the response for a
* single certificate and will typically include the responder certificate chain
* so 10K should be more than enough.
*
*/
#define MAX_STAPLING_DER 10240
/* Cached info stored in certificate ex_info. */
typedef struct {
/* Index in session cache SHA1 hash of certificate */
UCHAR idx[20];
/* Certificate ID for OCSP requests or NULL if ID cannot be determined */
OCSP_CERTID *cid;
/* Responder details */
char *uri;
} certinfo;
static void certinfo_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
int idx, long argl, void *argp)
{
certinfo *cinf = ptr;
if (!cinf)
return;
if (cinf->uri)
OPENSSL_free(cinf->uri);
OPENSSL_free(cinf);
}
static int stapling_ex_idx = -1;
void ssl_stapling_ex_init(void)
{
if (stapling_ex_idx != -1)
return;
stapling_ex_idx = X509_get_ex_new_index(0, "X509 cached OCSP info", 0, 0,
certinfo_free);
}
static X509 *stapling_get_issuer(modssl_ctx_t *mctx, X509 *x)
{
X509 *issuer = NULL;
int i;
X509_STORE *st = SSL_CTX_get_cert_store(mctx->ssl_ctx);
X509_STORE_CTX inctx;
for (i = 0; i < sk_X509_num(mctx->ssl_ctx->extra_certs); i++) {
issuer = sk_X509_value(mctx->ssl_ctx->extra_certs, i);
if (X509_check_issued(issuer, x) == X509_V_OK) {
CRYPTO_add(&issuer->references, 1, CRYPTO_LOCK_X509);
return issuer;
}
}
if (!X509_STORE_CTX_init(&inctx, st, NULL, NULL))
return 0;
if (X509_STORE_CTX_get1_issuer(&issuer, &inctx, x) <= 0)
issuer = NULL;
X509_STORE_CTX_cleanup(&inctx);
return issuer;
}
int ssl_stapling_init_cert(server_rec *s, modssl_ctx_t *mctx, X509 *x)
{
certinfo *cinf;
X509 *issuer = NULL;
STACK_OF(STRING) *aia = NULL;
if (x == NULL)
return 0;
cinf = X509_get_ex_data(x, stapling_ex_idx);
if (cinf) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"ssl_stapling_init_cert: certificate already initialized!");
return 0;
}
cinf = OPENSSL_malloc(sizeof(certinfo));
if (!cinf) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"ssl_stapling_init_cert: error allocating memory!");
return 0;
}
cinf->cid = NULL;
cinf->uri = NULL;
X509_set_ex_data(x, stapling_ex_idx, cinf);
issuer = stapling_get_issuer(mctx, x);
if (issuer == NULL) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"ssl_stapling_init_cert: Can't retrieve issuer certificate!");
return 0;
}
cinf->cid = OCSP_cert_to_id(NULL, x, issuer);
X509_free(issuer);
if (!cinf->cid)
return 0;
X509_digest(x, EVP_sha1(), cinf->idx, NULL);
aia = X509_get1_ocsp(x);
if (aia)
cinf->uri = sk_STRING_pop(aia);
if (!cinf->uri && !mctx->stapling_force_url) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"ssl_stapling_init_cert: no responder URL");
}
if (aia)
X509_email_free(aia);
return 1;
}
static certinfo *stapling_get_cert_info(server_rec *s, modssl_ctx_t *mctx,
SSL *ssl)
{
certinfo *cinf;
X509 *x;
x = SSL_get_certificate(ssl);
if (x == NULL)
return NULL;
cinf = X509_get_ex_data(x, stapling_ex_idx);
if (cinf && cinf->cid)
return cinf;
ap_log_error(APLOG_MARK, APLOG_INFO, 0, s,
"stapling_get_cert_info: stapling not supported for certificate");
return NULL;
}
/*
* OCSP response caching code. The response is preceded by a flag value
* which indicates whether the response was invalid when it was stored.
* the purpose of this flag is to avoid repeated queries to a server
* which has given an invalid response while allowing a response which
* has subsequently become invalid to be retried immediately.
*
* The key for the cache is the hash of the certificate the response
* is for.
*/
static BOOL stapling_cache_response(server_rec *s, modssl_ctx_t *mctx,
OCSP_RESPONSE *rsp, certinfo *cinf,
BOOL ok, apr_pool_t *pool)
{
SSLModConfigRec *mc = myModConfig(s);
unsigned char resp_der[MAX_STAPLING_DER];
unsigned char *p;
int resp_derlen;
BOOL rv;
time_t timeout;
resp_derlen = i2d_OCSP_RESPONSE(rsp, NULL) + 1;
if (resp_derlen <= 0) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"OCSP stapling response encode error??");
return FALSE;
}
if (resp_derlen > sizeof resp_der) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"OCSP stapling response too big (%u bytes)", resp_derlen);
return FALSE;
}
p = resp_der;
if (ok == TRUE) {
*p++ = 1;
timeout = mctx->stapling_cache_timeout;
}
else {
*p++ = 0;
timeout = mctx->stapling_errcache_timeout;
}
timeout += apr_time_sec(apr_time_now());
i2d_OCSP_RESPONSE(rsp, &p);
rv = mc->stapling_cache->store(mc->stapling_cache_context, s,
cinf->idx, sizeof(cinf->idx),
timeout, resp_der, resp_derlen, pool);
if (rv != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_cache_response: OCSP response session store error!");
return FALSE;
}
return TRUE;
}
static BOOL stapling_get_cached_response(server_rec *s, OCSP_RESPONSE **prsp,
BOOL *pok, certinfo *cinf,
apr_pool_t *pool)
{
SSLModConfigRec *mc = myModConfig(s);
apr_status_t rv;
OCSP_RESPONSE *rsp;
unsigned char resp_der[MAX_STAPLING_DER];
const unsigned char *p;
unsigned int resp_derlen = MAX_STAPLING_DER;
rv = mc->stapling_cache->retrieve(mc->stapling_cache_context, s,
cinf->idx, sizeof(cinf->idx),
resp_der, &resp_derlen, pool);
if (rv != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_get_cached_response: cache miss");
return TRUE;
}
if (resp_derlen <= 1) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_get_cached_response: response length invalid??");
return TRUE;
}
p = resp_der;
if (pok) {
if (*p)
*pok = TRUE;
else
*pok = FALSE;
}
p++;
resp_derlen--;
rsp = d2i_OCSP_RESPONSE(NULL, &p, resp_derlen);
if (!rsp) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_get_cached_response: response parse error??");
return TRUE;
}
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_get_cached_response: cache hit");
*prsp = rsp;
return TRUE;
}
static int stapling_set_response(SSL *ssl, OCSP_RESPONSE *rsp)
{
int rspderlen;
unsigned char *rspder = NULL;
rspderlen = i2d_OCSP_RESPONSE(rsp, &rspder);
if (rspderlen <= 0)
return 0;
SSL_set_tlsext_status_ocsp_resp(ssl, rspder, rspderlen);
return 1;
}
static int stapling_check_response(server_rec *s, modssl_ctx_t *mctx,
certinfo *cinf, OCSP_RESPONSE *rsp,
BOOL *pok)
{
int status, reason;
OCSP_BASICRESP *bs = NULL;
ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
int response_status = OCSP_response_status(rsp);
if (pok)
*pok = FALSE;
/* Check to see if response is an error. If so we automatically accept
* it because it would have expired from the cache if it was time to
* retry.
*/
if (response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
if (mctx->stapling_return_errors)
return SSL_TLSEXT_ERR_OK;
else
return SSL_TLSEXT_ERR_NOACK;
}
bs = OCSP_response_get1_basic(rsp);
if (bs == NULL) {
/* If we can't parse response just pass it to client */
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_check_response: Error Parsing Response!");
return SSL_TLSEXT_ERR_OK;
}
if (!OCSP_resp_find_status(bs, cinf->cid, &status, &reason, &rev,
&thisupd, &nextupd)) {
/* If ID not present just pass back to client */
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_check_response: certificate ID not present in response!");
}
else {
if (OCSP_check_validity(thisupd, nextupd,
mctx->stapling_resptime_skew,
mctx->stapling_resp_maxage)) {
if (pok)
*pok = TRUE;
}
else {
/* If pok is not NULL response was direct from a responder and
* the times should be valide. If pok is NULL the response was
* retrieved from cache and it is expected to subsequently expire
*/
if (pok) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_check_response: response times invalid");
}
else {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_check_response: cached response expired");
}
OCSP_BASICRESP_free(bs);
return SSL_TLSEXT_ERR_NOACK;
}
}
OCSP_BASICRESP_free(bs);
return SSL_TLSEXT_ERR_OK;
}
static BOOL stapling_renew_response(server_rec *s, modssl_ctx_t *mctx, SSL *ssl,
certinfo *cinf, OCSP_RESPONSE **prsp,
apr_pool_t *pool)
{
conn_rec *conn = (conn_rec *)SSL_get_app_data(ssl);
apr_pool_t *vpool;
OCSP_REQUEST *req = NULL;
OCSP_CERTID *id = NULL;
STACK_OF(X509_EXTENSION) *exts;
int i;
BOOL ok = FALSE;
BOOL rv = TRUE;
const char *ocspuri;
apr_uri_t uri;
*prsp = NULL;
/* Build up OCSP query from server certificate info */
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_renew_response: querying responder");
req = OCSP_REQUEST_new();
if (!req)
goto err;
id = OCSP_CERTID_dup(cinf->cid);
if (!id)
goto err;
if (!OCSP_request_add0_id(req, id))
goto err;
id = NULL;
/* Add any extensions to the request */
SSL_get_tlsext_status_exts(ssl, &exts);
for (i = 0; i < sk_X509_EXTENSION_num(exts); i++) {
X509_EXTENSION *ext = sk_X509_EXTENSION_value(exts, i);
if (!OCSP_REQUEST_add_ext(req, ext, -1))
goto err;
}
if (mctx->stapling_force_url)
ocspuri = mctx->stapling_force_url;
else
ocspuri = cinf->uri;
/* Create a temporary pool to constrain memory use */
apr_pool_create(&vpool, conn->pool);
ok = apr_uri_parse(vpool, ocspuri, &uri);
if (ok != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_renew_response: Error parsing uri %s",
ocspuri);
rv = FALSE;
goto done;
}
else if (strcmp(uri.scheme, "http")) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_renew_response: Unsupported uri %s", ocspuri);
rv = FALSE;
goto done;
}
*prsp = modssl_dispatch_ocsp_request(&uri, mctx->stapling_responder_timeout,
req, conn, vpool);
apr_pool_destroy(vpool);
if (!*prsp) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_renew_response: responder error");
if (mctx->stapling_fake_trylater) {
*prsp = OCSP_response_create(OCSP_RESPONSE_STATUS_TRYLATER, NULL);
}
else {
goto done;
}
}
else {
int response_status = OCSP_response_status(*prsp);
if (response_status == OCSP_RESPONSE_STATUS_SUCCESSFUL) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_renew_response: query response received");
stapling_check_response(s, mctx, cinf, *prsp, &ok);
if (ok == FALSE) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_renew_response: error in retreived response!");
}
}
else {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_renew_response: responder error %s",
OCSP_response_status_str(response_status));
}
}
if (stapling_cache_response(s, mctx, *prsp, cinf, ok, pool) == FALSE) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_renew_response: error caching response!");
}
done:
if (id)
OCSP_CERTID_free(id);
if (req)
OCSP_REQUEST_free(req);
return rv;
err:
rv = FALSE;
goto done;
}
/*
* SSLStaplingMutex operations. Similar to SSL mutex except a mutex is
* mandatory if stapling is enabled.
*/
int ssl_stapling_mutex_init(server_rec *s, apr_pool_t *p)
{
SSLModConfigRec *mc = myModConfig(s);
SSLSrvConfigRec *sc = mySrvConfig(s);
apr_status_t rv;
if (mc->stapling_mutex || sc->server->stapling_enabled != TRUE) {
return TRUE;
}
if ((rv = ap_global_mutex_create(&mc->stapling_mutex,
ssl_stapling_mutex_type, NULL, s,
s->process->pool, 0)) != APR_SUCCESS) {
return FALSE;
}
return TRUE;
}
int ssl_stapling_mutex_reinit(server_rec *s, apr_pool_t *p)
{
SSLModConfigRec *mc = myModConfig(s);
apr_status_t rv;
const char *lockfile;
if (mc->stapling_mutex == NULL) {
return TRUE;
}
lockfile = apr_global_mutex_lockfile(mc->stapling_mutex);
if ((rv = apr_global_mutex_child_init(&mc->stapling_mutex,
lockfile, p)) != APR_SUCCESS) {
if (lockfile) {
ap_log_error(APLOG_MARK, APLOG_ERR, rv, s,
"Cannot reinit %s mutex with file `%s'",
ssl_stapling_mutex_type, lockfile);
}
else {
ap_log_error(APLOG_MARK, APLOG_WARNING, rv, s,
"Cannot reinit %s mutex", ssl_stapling_mutex_type);
}
return FALSE;
}
return TRUE;
}
static int stapling_mutex_on(server_rec *s)
{
SSLModConfigRec *mc = myModConfig(s);
apr_status_t rv;
if ((rv = apr_global_mutex_lock(mc->stapling_mutex)) != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_WARNING, rv, s,
"Failed to acquire OCSP stapling lock");
return FALSE;
}
return TRUE;
}
static int stapling_mutex_off(server_rec *s)
{
SSLModConfigRec *mc = myModConfig(s);
apr_status_t rv;
if ((rv = apr_global_mutex_unlock(mc->stapling_mutex)) != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_WARNING, rv, s,
"Failed to release OCSP stapling lock");
return FALSE;
}
return TRUE;
}
/* Certificate Status callback. This is called when a client includes a
* certificate status request extension.
*
* Check for cached responses in session cache. If valid send back to
* client. If absent or no longer valid query responder and update
* cache. */
static int stapling_cb(SSL *ssl, void *arg)
{
conn_rec *conn = (conn_rec *)SSL_get_app_data(ssl);
server_rec *s = mySrvFromConn(conn);
SSLSrvConfigRec *sc = mySrvConfig(s);
SSLConnRec *sslconn = myConnConfig(conn);
modssl_ctx_t *mctx = myCtxConfig(sslconn, sc);
certinfo *cinf = NULL;
OCSP_RESPONSE *rsp = NULL;
int rv;
BOOL ok;
if (sc->server->stapling_enabled != TRUE) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_cb: OCSP Stapling disabled");
return SSL_TLSEXT_ERR_NOACK;
}
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_cb: OCSP Stapling callback called");
cinf = stapling_get_cert_info(s, mctx, ssl);
if (cinf == NULL) {
return SSL_TLSEXT_ERR_NOACK;
}
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_cb: retrieved cached certificate data");
/* Check to see if we already have a response for this certificate */
stapling_mutex_on(s);
rv = stapling_get_cached_response(s, &rsp, &ok, cinf, conn->pool);
if (rv == FALSE) {
stapling_mutex_off(s);
return SSL_TLSEXT_ERR_ALERT_FATAL;
}
if (rsp) {
/* see if response is acceptable */
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_cb: retrieved cached response");
rv = stapling_check_response(s, mctx, cinf, rsp, NULL);
if (rv == SSL_TLSEXT_ERR_ALERT_FATAL) {
OCSP_RESPONSE_free(rsp);
stapling_mutex_off(s);
return SSL_TLSEXT_ERR_ALERT_FATAL;
}
else if (rv == SSL_TLSEXT_ERR_NOACK) {
/* Error in response. If this error was not present when it was
* stored (i.e. response no longer valid) then it can be
* renewed straight away.
*
* If the error *was* present at the time it was stored then we
* don't renew the response straight away we just wait for the
* cached response to expire.
*/
if (ok) {
OCSP_RESPONSE_free(rsp);
rsp = NULL;
}
else if (!mctx->stapling_return_errors) {
OCSP_RESPONSE_free(rsp);
stapling_mutex_off(s);
return SSL_TLSEXT_ERR_NOACK;
}
}
}
if (rsp == NULL) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_cb: renewing cached response");
rv = stapling_renew_response(s, mctx, ssl, cinf, &rsp, conn->pool);
if (rv == FALSE) {
stapling_mutex_off(s);
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"stapling_cb: fatal error");
return SSL_TLSEXT_ERR_ALERT_FATAL;
}
}
stapling_mutex_off(s);
if (rsp) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_cb: setting response");
if (!stapling_set_response(ssl, rsp))
return SSL_TLSEXT_ERR_ALERT_FATAL;
return SSL_TLSEXT_ERR_OK;
}
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
"stapling_cb: no response available");
return SSL_TLSEXT_ERR_NOACK;
}
void modssl_init_stapling(server_rec *s, apr_pool_t *p, apr_pool_t *ptemp,
modssl_ctx_t *mctx)
{
SSL_CTX *ctx = mctx->ssl_ctx;
SSLModConfigRec *mc = myModConfig(s);
if (mc->stapling_cache == NULL) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
"SSLStapling: no stapling cache available");
ssl_die();
}
/* Set some default values for parameters if they are not set */
if (mctx->stapling_resptime_skew == UNSET) {
mctx->stapling_resptime_skew = 60 * 5;
}
if (mctx->stapling_cache_timeout == UNSET) {
mctx->stapling_cache_timeout = 3600;
}
if (mctx->stapling_return_errors == UNSET) {
mctx->stapling_return_errors = TRUE;
}
if (mctx->stapling_fake_trylater == UNSET) {
mctx->stapling_fake_trylater = TRUE;
}
if (mctx->stapling_errcache_timeout == UNSET) {
mctx->stapling_errcache_timeout = 600;
}
if (mctx->stapling_responder_timeout == UNSET) {
mctx->stapling_responder_timeout = 10 * APR_USEC_PER_SEC;
}
SSL_CTX_set_tlsext_status_cb(ctx, stapling_cb);
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, "OCSP stapling initialized");
}
#endif