TLS server: OCSP stapling with ocsp_multi option (RFC 6961)

This allows hostapd with the internal TLS server implementation to
support the extended OCSP stapling mechanism with multiple responses
(ocsp_stapling_response_multi).

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

src/crypto/tls_internal.c

@@ -334,6 +334,9 @@ int tls_global_set_params(void *tls_ctx,
 	if (params->ocsp_stapling_response)
 		cred->ocsp_stapling_response =
 			os_strdup(params->ocsp_stapling_response);
+	if (params->ocsp_stapling_response_multi)
+		cred->ocsp_stapling_response_multi =
+			os_strdup(params->ocsp_stapling_response_multi);
 
 	return 0;
 #else /* CONFIG_TLS_INTERNAL_SERVER */

src/tls/tlsv1_common.h

@@ -170,6 +170,7 @@ enum {
 #define TLS_EXT_TRUNCATED_HMAC			4 /* RFC 4366 */
 #define TLS_EXT_STATUS_REQUEST			5 /* RFC 4366 */
 #define TLS_EXT_SIGNATURE_ALGORITHMS		13 /* RFC 5246 */
+#define TLS_EXT_STATUS_REQUEST_V2		17 /* RFC 6961 */
 #define TLS_EXT_SESSION_TICKET			35 /* RFC 4507 */
 
 #define TLS_EXT_PAC_OPAQUE TLS_EXT_SESSION_TICKET /* EAP-FAST terminology */

src/tls/tlsv1_cred.c

@@ -37,6 +37,7 @@ void tlsv1_cred_free(struct tlsv1_credentials *cred)
 	os_free(cred->dh_p);
 	os_free(cred->dh_g);
 	os_free(cred->ocsp_stapling_response);
+	os_free(cred->ocsp_stapling_response_multi);
 	os_free(cred);
 }
 

src/tls/tlsv1_cred.h

@@ -26,6 +26,7 @@ struct tlsv1_credentials {
 	size_t dh_g_len;
 
 	char *ocsp_stapling_response;
+	char *ocsp_stapling_response_multi;
 };
 
 

src/tls/tlsv1_server_i.h

@@ -56,6 +56,8 @@ struct tlsv1_server {
 
 	int use_session_ticket;
 	unsigned int status_request:1;
+	unsigned int status_request_v2:1;
+	unsigned int status_request_multi:1;
 
 	u8 *dh_secret;
 	size_t dh_secret_len;

src/tls/tlsv1_server_read.c

@@ -46,6 +46,78 @@ static int testing_cipher_suite_filter(struct tlsv1_server *conn, u16 suite)
 }
 
 
+static void tls_process_status_request_item(struct tlsv1_server *conn,
+					    const u8 *req, size_t req_len)
+{
+	const u8 *pos, *end;
+	u8 status_type;
+
+	pos = req;
+	end = req + req_len;
+
+	/*
+	 * RFC 6961, 2.2:
+	 * struct {
+	 *   CertificateStatusType status_type;
+	 *   uint16 request_length;
+	 *   select (status_type) {
+	 *     case ocsp: OCSPStatusRequest;
+	 *     case ocsp_multi: OCSPStatusRequest;
+	 *   } request;
+	 * } CertificateStatusRequestItemV2;
+	 *
+	 * enum { ocsp(1), ocsp_multi(2), (255) } CertificateStatusType;
+	 */
+
+	if (end - pos < 1)
+		return; /* Truncated data */
+
+	status_type = *pos++;
+	wpa_printf(MSG_DEBUG, "TLSv1: CertificateStatusType %u", status_type);
+	if (status_type != 1 && status_type != 2)
+		return; /* Unsupported status type */
+	/*
+	 * For now, only OCSP stapling is supported, so ignore the specific
+	 * request, if any.
+	 */
+	wpa_hexdump(MSG_DEBUG, "TLSv1: OCSPStatusRequest", pos, end - pos);
+
+	if (status_type == 2)
+		conn->status_request_multi = 1;
+}
+
+
+static void tls_process_status_request_v2(struct tlsv1_server *conn,
+					  const u8 *ext, size_t ext_len)
+{
+	const u8 *pos, *end;
+
+	conn->status_request_v2 = 1;
+
+	pos = ext;
+	end = ext + ext_len;
+
+	/*
+	 * RFC 6961, 2.2:
+	 * struct {
+	 *   CertificateStatusRequestItemV2
+	 *                    certificate_status_req_list<1..2^16-1>;
+	 * } CertificateStatusRequestListV2;
+	 */
+
+	while (end - pos >= 2) {
+		u16 len;
+
+		len = WPA_GET_BE16(pos);
+		pos += 2;
+		if (len > end - pos)
+			break; /* Truncated data */
+		tls_process_status_request_item(conn, pos, len);
+		pos += len;
+	}
+}
+
+
 static int tls_process_client_hello(struct tlsv1_server *conn, u8 ct,
 				    const u8 *in_data, size_t *in_len)
 {
@@ -269,6 +341,9 @@ static int tls_process_client_hello(struct tlsv1_server *conn, u8 ct,
 				}
 			} else if (ext_type == TLS_EXT_STATUS_REQUEST) {
 				conn->status_request = 1;
+			} else if (ext_type == TLS_EXT_STATUS_REQUEST_V2) {
+				tls_process_status_request_v2(conn, pos,
+							      ext_len);
 			}
 
 			pos += ext_len;

src/tls/tlsv1_server_write.c

@@ -111,6 +111,18 @@ static int tls_write_server_hello(struct tlsv1_server *conn,
 		pos += 2;
 	}
 
+	if (conn->status_request_v2) {
+		/*
+		  Add a status_request_v2 extension with empty extension_data
+		*/
+		/* ExtensionsType extension_type = status_request_v2(17) */
+		WPA_PUT_BE16(pos, TLS_EXT_STATUS_REQUEST_V2);
+		pos += 2;
+		/* opaque extension_data<0..2^16-1> length */
+		WPA_PUT_BE16(pos, 0);
+		pos += 2;
+	}
+
 	if (conn->session_ticket && conn->session_ticket_cb) {
 		int res = conn->session_ticket_cb(
 			conn->session_ticket_cb_ctx,
@@ -264,30 +276,31 @@ static int tls_write_server_certificate(struct tlsv1_server *conn,
 
 
 static int tls_write_server_certificate_status(struct tlsv1_server *conn,
-					       u8 **msgpos, u8 *end)
+					       u8 **msgpos, u8 *end,
+					       int ocsp_multi,
+					       char *ocsp_resp,
+					       size_t ocsp_resp_len)
 {
 	u8 *pos, *rhdr, *hs_start, *hs_length;
-	char *resp;
-	size_t rlen, len;
+	size_t rlen;
 
-	if (!conn->status_request)
-		return 0; /* Client did not request certificate status */
-	if (!conn->cred->ocsp_stapling_response)
-		return 0; /* No cached OCSP stapling response */
-	resp = os_readfile(conn->cred->ocsp_stapling_response, &len);
-	if (!resp)
-		return 0; /* No cached OCSP stapling response */
+	if (!ocsp_resp) {
+		 /*
+		  * Client did not request certificate status or there is no
+		  * matching response cached.
+		  */
+		return 0;
+	}
 
 	pos = *msgpos;
-	if (TLS_RECORD_HEADER_LEN + 1 + 3 + 1 + 3 + len >
+	if (TLS_RECORD_HEADER_LEN + 1 + 3 + 1 + 3 + ocsp_resp_len >
 	    (unsigned int) (end - pos)) {
 		tlsv1_server_alert(conn, TLS_ALERT_LEVEL_FATAL,
 				   TLS_ALERT_INTERNAL_ERROR);
-		os_free(resp);
 		return -1;
 	}
 
-	tlsv1_server_log(conn, "Send CertificateStatus");
+	tlsv1_server_log(conn, "Send CertificateStatus (multi=%d)", ocsp_multi);
 	rhdr = pos;
 	pos += TLS_RECORD_HEADER_LEN;
 
@@ -307,20 +320,27 @@ static int tls_write_server_certificate_status(struct tlsv1_server *conn,
 	 *     CertificateStatusType status_type;
 	 *     select (status_type) {
 	 *         case ocsp: OCSPResponse;
+	 *         case ocsp_multi: OCSPResponseList;
 	 *     } response;
 	 * } CertificateStatus;
 	 *
 	 * opaque OCSPResponse<1..2^24-1>;
+	 *
+	 * struct {
+	 *   OCSPResponse ocsp_response_list<1..2^24-1>;
+	 * } OCSPResponseList;
 	 */
 
 	/* CertificateStatusType status_type */
-	*pos++ = 1; /* ocsp(1) */
+	if (ocsp_multi)
+		*pos++ = 2; /* ocsp_multi(2) */
+	else
+		*pos++ = 1; /* ocsp(1) */
 	/* uint24 length of OCSPResponse */
-	WPA_PUT_BE24(pos, len);
+	WPA_PUT_BE24(pos, ocsp_resp_len);
 	pos += 3;
-	os_memcpy(pos, resp, len);
-	os_free(resp);
-	pos += len;
+	os_memcpy(pos, ocsp_resp, ocsp_resp_len);
+	pos += ocsp_resp_len;
 
 	WPA_PUT_BE24(hs_length, pos - hs_length - 3);
 
@@ -908,34 +928,46 @@ static u8 * tls_send_server_hello(struct tlsv1_server *conn, size_t *out_len)
 {
 	u8 *msg, *end, *pos;
 	size_t msglen;
+	int ocsp_multi = 0;
+	char *ocsp_resp = NULL;
+	size_t ocsp_resp_len = 0;
 
 	*out_len = 0;
 
-	msglen = 1000 + tls_server_cert_chain_der_len(conn);
-	if (conn->status_request && conn->cred->ocsp_stapling_response) {
-		char *resp;
-		size_t len;
-
-		resp = os_readfile(conn->cred->ocsp_stapling_response, &len);
-		if (resp) {
-			msglen += 10 + len;
-			os_free(resp);
-		}
+	if (conn->status_request_multi &&
+	    conn->cred->ocsp_stapling_response_multi) {
+		ocsp_resp = os_readfile(
+			conn->cred->ocsp_stapling_response_multi,
+			&ocsp_resp_len);
+		ocsp_multi = 1;
+	} else if ((conn->status_request || conn->status_request_v2) &&
+		   conn->cred->ocsp_stapling_response) {
+		ocsp_resp = os_readfile(conn->cred->ocsp_stapling_response,
+					&ocsp_resp_len);
 	}
+	if (!ocsp_resp)
+		ocsp_resp_len = 0;
+
+	msglen = 1000 + tls_server_cert_chain_der_len(conn) + ocsp_resp_len;
 
 	msg = os_malloc(msglen);
-	if (msg == NULL)
+	if (msg == NULL) {
+		os_free(ocsp_resp);
 		return NULL;
+	}
 
 	pos = msg;
 	end = msg + msglen;
 
 	if (tls_write_server_hello(conn, &pos, end) < 0) {
 		os_free(msg);
+		os_free(ocsp_resp);
 		return NULL;
 	}
 
 	if (conn->use_session_ticket) {
+		os_free(ocsp_resp);
+
 		/* Abbreviated handshake using session ticket; RFC 4507 */
 		if (tls_write_server_change_cipher_spec(conn, &pos, end) < 0 ||
 		    tls_write_server_finished(conn, &pos, end) < 0) {
@@ -952,13 +984,16 @@ static u8 * tls_send_server_hello(struct tlsv1_server *conn, size_t *out_len)
 
 	/* Full handshake */
 	if (tls_write_server_certificate(conn, &pos, end) < 0 ||
-	    tls_write_server_certificate_status(conn, &pos, end) < 0 ||
+	    tls_write_server_certificate_status(conn, &pos, end, ocsp_multi,
+						ocsp_resp, ocsp_resp_len) < 0 ||
 	    tls_write_server_key_exchange(conn, &pos, end) < 0 ||
 	    tls_write_server_certificate_request(conn, &pos, end) < 0 ||
 	    tls_write_server_hello_done(conn, &pos, end) < 0) {
 		os_free(msg);
+		os_free(ocsp_resp);
 		return NULL;
 	}
+	os_free(ocsp_resp);
 
 	*out_len = pos - msg;