Add support for OCSP stapling to validate server certificate
When using OpenSSL with TLS-based EAP methods, wpa_supplicant can now be configured to use OCSP stapling (TLS certificate status request) with ocsp=1 network block parameter. ocsp=2 can be used to require valid OCSP response before connection is allowed to continue. hostapd as EAP server can be configured to return cached OCSP response using the new ocsp_stapling_response parameter and an external mechanism for updating the response data (e.g., "openssl ocsp ..." command). This allows wpa_supplicant to verify that the server certificate has not been revoked as part of the EAP-TLS/PEAP/TTLS/FAST handshake before actual data connection has been established (i.e., when a CRL could not be fetched even if a distribution point were specified). Signed-hostap: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen
parent
72950ed240
commit
080585c01a
11 changed files with 263 additions and 4 deletions
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@ -1,6 +1,6 @@
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/*
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* SSL/TLS interface functions for OpenSSL
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* Copyright (c) 2004-2011, Jouni Malinen <j@w1.fi>
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* Copyright (c) 2004-2013, Jouni Malinen <j@w1.fi>
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*
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* This software may be distributed under the terms of the BSD license.
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* See README for more details.
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@ -51,6 +51,13 @@
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#endif
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#endif
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#ifdef SSL_set_tlsext_status_type
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#ifndef OPENSSL_NO_TLSEXT
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#define HAVE_OCSP
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#include <openssl/ocsp.h>
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#endif /* OPENSSL_NO_TLSEXT */
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#endif /* SSL_set_tlsext_status_type */
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static int tls_openssl_ref_count = 0;
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struct tls_context {
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@ -58,6 +65,7 @@ struct tls_context {
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union tls_event_data *data);
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void *cb_ctx;
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int cert_in_cb;
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char *ocsp_stapling_response;
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};
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static struct tls_context *tls_global = NULL;
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@ -88,6 +96,9 @@ struct tls_connection {
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u8 srv_cert_hash[32];
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unsigned int flags;
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X509 *peer_cert;
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X509 *peer_issuer;
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};
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@ -827,6 +838,8 @@ void tls_deinit(void *ssl_ctx)
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ERR_remove_state(0);
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ERR_free_strings();
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EVP_cleanup();
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os_free(tls_global->ocsp_stapling_response);
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tls_global->ocsp_stapling_response = NULL;
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os_free(tls_global);
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tls_global = NULL;
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}
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@ -1241,6 +1254,12 @@ static int tls_verify_cb(int preverify_ok, X509_STORE_CTX *x509_ctx)
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conn = SSL_get_app_data(ssl);
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if (conn == NULL)
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return 0;
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if (depth == 0)
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conn->peer_cert = err_cert;
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else if (depth == 1)
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conn->peer_issuer = err_cert;
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context = conn->context;
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match = conn->subject_match;
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altmatch = conn->altsubject_match;
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@ -2755,11 +2774,187 @@ int tls_connection_get_write_alerts(void *ssl_ctx, struct tls_connection *conn)
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}
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#ifdef HAVE_OCSP
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static void ocsp_debug_print_resp(OCSP_RESPONSE *rsp)
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{
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#ifndef CONFIG_NO_STDOUT_DEBUG
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extern int wpa_debug_level;
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BIO *out;
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size_t rlen;
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char *txt;
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int res;
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if (wpa_debug_level > MSG_DEBUG)
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return;
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out = BIO_new(BIO_s_mem());
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if (!out)
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return;
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OCSP_RESPONSE_print(out, rsp, 0);
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rlen = BIO_ctrl_pending(out);
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txt = os_malloc(rlen + 1);
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if (!txt) {
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BIO_free(out);
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return;
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}
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res = BIO_read(out, txt, rlen);
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if (res > 0) {
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txt[res] = '\0';
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wpa_printf(MSG_DEBUG, "OpenSSL: OCSP Response\n%s", txt);
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}
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os_free(txt);
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BIO_free(out);
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#endif /* CONFIG_NO_STDOUT_DEBUG */
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}
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static int ocsp_resp_cb(SSL *s, void *arg)
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{
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struct tls_connection *conn = arg;
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const unsigned char *p;
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int len, status, reason;
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OCSP_RESPONSE *rsp;
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OCSP_BASICRESP *basic;
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OCSP_CERTID *id;
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ASN1_GENERALIZEDTIME *produced_at, *this_update, *next_update;
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len = SSL_get_tlsext_status_ocsp_resp(s, &p);
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if (!p) {
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wpa_printf(MSG_DEBUG, "OpenSSL: No OCSP response received");
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return (conn->flags & TLS_CONN_REQUIRE_OCSP) ? 0 : 1;
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}
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wpa_hexdump(MSG_DEBUG, "OpenSSL: OCSP response", p, len);
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rsp = d2i_OCSP_RESPONSE(NULL, &p, len);
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if (!rsp) {
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wpa_printf(MSG_INFO, "OpenSSL: Failed to parse OCSP response");
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return 0;
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}
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ocsp_debug_print_resp(rsp);
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status = OCSP_response_status(rsp);
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if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
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wpa_printf(MSG_INFO, "OpenSSL: OCSP responder error %d (%s)",
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status, OCSP_response_status_str(status));
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return 0;
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}
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basic = OCSP_response_get1_basic(rsp);
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if (!basic) {
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wpa_printf(MSG_INFO, "OpenSSL: Could not find BasicOCSPResponse");
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return 0;
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}
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status = OCSP_basic_verify(basic, NULL, SSL_CTX_get_cert_store(s->ctx),
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0);
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if (status <= 0) {
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tls_show_errors(MSG_INFO, __func__,
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"OpenSSL: OCSP response failed verification");
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OCSP_BASICRESP_free(basic);
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OCSP_RESPONSE_free(rsp);
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return 0;
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}
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wpa_printf(MSG_DEBUG, "OpenSSL: OCSP response verification succeeded");
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if (!conn->peer_cert || !conn->peer_issuer) {
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wpa_printf(MSG_DEBUG, "OpenSSL: Peer certificate or issue certificate not available for OCSP status check");
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OCSP_BASICRESP_free(basic);
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OCSP_RESPONSE_free(rsp);
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return 0;
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}
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id = OCSP_cert_to_id(NULL, conn->peer_cert, conn->peer_issuer);
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if (!id) {
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wpa_printf(MSG_DEBUG, "OpenSSL: Could not create OCSP certificate identifier");
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OCSP_BASICRESP_free(basic);
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OCSP_RESPONSE_free(rsp);
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return 0;
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}
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if (!OCSP_resp_find_status(basic, id, &status, &reason, &produced_at,
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&this_update, &next_update)) {
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wpa_printf(MSG_INFO, "OpenSSL: Could not find current server certificate from OCSP response%s",
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(conn->flags & TLS_CONN_REQUIRE_OCSP) ? "" :
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" (OCSP not required)");
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OCSP_BASICRESP_free(basic);
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OCSP_RESPONSE_free(rsp);
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return (conn->flags & TLS_CONN_REQUIRE_OCSP) ? 0 : 1;
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}
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if (!OCSP_check_validity(this_update, next_update, 5 * 60, -1)) {
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tls_show_errors(MSG_INFO, __func__,
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"OpenSSL: OCSP status times invalid");
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OCSP_BASICRESP_free(basic);
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OCSP_RESPONSE_free(rsp);
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return 0;
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}
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OCSP_BASICRESP_free(basic);
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OCSP_RESPONSE_free(rsp);
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wpa_printf(MSG_DEBUG, "OpenSSL: OCSP status for server certificate: %s",
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OCSP_cert_status_str(status));
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if (status == V_OCSP_CERTSTATUS_GOOD)
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return 1;
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if (status == V_OCSP_CERTSTATUS_REVOKED)
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return 0;
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if (conn->flags & TLS_CONN_REQUIRE_OCSP) {
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wpa_printf(MSG_DEBUG, "OpenSSL: OCSP status unknown, but OCSP required");
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return 0;
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}
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wpa_printf(MSG_DEBUG, "OpenSSL: OCSP status unknown, but OCSP was not required, so allow connection to continue");
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return 1;
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}
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static int ocsp_status_cb(SSL *s, void *arg)
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{
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char *tmp;
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char *resp;
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size_t len;
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if (tls_global->ocsp_stapling_response == NULL) {
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wpa_printf(MSG_DEBUG, "OpenSSL: OCSP status callback - no response configured");
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return SSL_TLSEXT_ERR_OK;
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}
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resp = os_readfile(tls_global->ocsp_stapling_response, &len);
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if (resp == NULL) {
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wpa_printf(MSG_DEBUG, "OpenSSL: OCSP status callback - could not read response file");
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/* TODO: Build OCSPResponse with responseStatus = internalError
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*/
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return SSL_TLSEXT_ERR_OK;
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}
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wpa_printf(MSG_DEBUG, "OpenSSL: OCSP status callback - send cached response");
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tmp = OPENSSL_malloc(len);
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if (tmp == NULL) {
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os_free(resp);
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return SSL_TLSEXT_ERR_ALERT_FATAL;
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}
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os_memcpy(tmp, resp, len);
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os_free(resp);
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SSL_set_tlsext_status_ocsp_resp(s, tmp, len);
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return SSL_TLSEXT_ERR_OK;
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}
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#endif /* HAVE_OCSP */
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int tls_connection_set_params(void *tls_ctx, struct tls_connection *conn,
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const struct tls_connection_params *params)
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{
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int ret;
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unsigned long err;
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SSL_CTX *ssl_ctx = tls_ctx;
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if (conn == NULL)
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return -1;
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@ -2827,6 +3022,14 @@ int tls_connection_set_params(void *tls_ctx, struct tls_connection *conn,
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SSL_clear_options(conn->ssl, SSL_OP_NO_TICKET);
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#endif /* SSL_OP_NO_TICKET */
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#ifdef HAVE_OCSP
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if (params->flags & TLS_CONN_REQUEST_OCSP) {
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SSL_set_tlsext_status_type(conn->ssl, TLSEXT_STATUSTYPE_ocsp);
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SSL_CTX_set_tlsext_status_cb(ssl_ctx, ocsp_resp_cb);
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SSL_CTX_set_tlsext_status_arg(ssl_ctx, conn);
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}
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#endif /* HAVE_OCSP */
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conn->flags = params->flags;
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tls_get_errors(tls_ctx);
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@ -2869,6 +3072,17 @@ int tls_global_set_params(void *tls_ctx,
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SSL_CTX_clear_options(ssl_ctx, SSL_OP_NO_TICKET);
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#endif /* SSL_OP_NO_TICKET */
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#ifdef HAVE_OCSP
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SSL_CTX_set_tlsext_status_cb(ssl_ctx, ocsp_status_cb);
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SSL_CTX_set_tlsext_status_arg(ssl_ctx, ssl_ctx);
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os_free(tls_global->ocsp_stapling_response);
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if (params->ocsp_stapling_response)
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tls_global->ocsp_stapling_response =
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os_strdup(params->ocsp_stapling_response);
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else
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tls_global->ocsp_stapling_response = NULL;
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#endif /* HAVE_OCSP */
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return 0;
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}
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