446 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			C
		
	
	
	
			
		
		
	
	
			446 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			C
		
	
	
	
| /*
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|  * QEMU VNC display driver: TLS helpers
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|  *
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|  * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
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|  * Copyright (C) 2006 Fabrice Bellard
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|  * Copyright (C) 2009 Red Hat, Inc
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|  *
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|  * Permission is hereby granted, free of charge, to any person obtaining a copy
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|  * of this software and associated documentation files (the "Software"), to deal
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|  * in the Software without restriction, including without limitation the rights
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|  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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|  * copies of the Software, and to permit persons to whom the Software is
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|  * furnished to do so, subject to the following conditions:
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|  *
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|  * The above copyright notice and this permission notice shall be included in
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|  * all copies or substantial portions of the Software.
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|  *
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|  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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|  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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|  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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|  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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|  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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|  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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|  * THE SOFTWARE.
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|  */
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| 
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| #include "qemu-x509.h"
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| #include "vnc.h"
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| #include "qemu_socket.h"
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| 
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| #if defined(_VNC_DEBUG) && _VNC_DEBUG >= 2
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| /* Very verbose, so only enabled for _VNC_DEBUG >= 2 */
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| static void vnc_debug_gnutls_log(int level, const char* str) {
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|     VNC_DEBUG("%d %s", level, str);
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| }
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| #endif /* defined(_VNC_DEBUG) && _VNC_DEBUG >= 2 */
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| 
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| 
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| #define DH_BITS 1024
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| static gnutls_dh_params_t dh_params;
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| 
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| static int vnc_tls_initialize(void)
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| {
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|     static int tlsinitialized = 0;
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| 
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|     if (tlsinitialized)
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|         return 1;
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| 
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|     if (gnutls_global_init () < 0)
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|         return 0;
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| 
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|     /* XXX ought to re-generate diffie-hellmen params periodically */
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|     if (gnutls_dh_params_init (&dh_params) < 0)
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|         return 0;
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|     if (gnutls_dh_params_generate2 (dh_params, DH_BITS) < 0)
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|         return 0;
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| 
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| #if defined(_VNC_DEBUG) && _VNC_DEBUG >= 2
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|     gnutls_global_set_log_level(10);
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|     gnutls_global_set_log_function(vnc_debug_gnutls_log);
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| #endif
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| 
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|     tlsinitialized = 1;
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| 
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|     return 1;
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| }
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| 
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| static ssize_t vnc_tls_push(gnutls_transport_ptr_t transport,
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|                             const void *data,
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|                             size_t len) {
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|     struct VncState *vs = (struct VncState *)transport;
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|     int ret;
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| 
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|  retry:
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|     ret = send(vs->csock, data, len, 0);
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|     if (ret < 0) {
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|         if (errno == EINTR)
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|             goto retry;
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|         return -1;
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|     }
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|     return ret;
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| }
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| 
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| 
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| static ssize_t vnc_tls_pull(gnutls_transport_ptr_t transport,
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|                             void *data,
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|                             size_t len) {
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|     struct VncState *vs = (struct VncState *)transport;
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|     int ret;
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| 
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|  retry:
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|     ret = recv(vs->csock, data, len, 0);
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|     if (ret < 0) {
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|         if (errno == EINTR)
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|             goto retry;
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|         return -1;
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|     }
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|     return ret;
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| }
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| 
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| 
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| static gnutls_anon_server_credentials vnc_tls_initialize_anon_cred(void)
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| {
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|     gnutls_anon_server_credentials anon_cred;
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|     int ret;
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| 
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|     if ((ret = gnutls_anon_allocate_server_credentials(&anon_cred)) < 0) {
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|         VNC_DEBUG("Cannot allocate credentials %s\n", gnutls_strerror(ret));
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|         return NULL;
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|     }
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| 
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|     gnutls_anon_set_server_dh_params(anon_cred, dh_params);
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| 
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|     return anon_cred;
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| }
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| 
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| 
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| static gnutls_certificate_credentials_t vnc_tls_initialize_x509_cred(VncDisplay *vd)
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| {
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|     gnutls_certificate_credentials_t x509_cred;
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|     int ret;
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| 
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|     if (!vd->tls.x509cacert) {
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|         VNC_DEBUG("No CA x509 certificate specified\n");
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|         return NULL;
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|     }
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|     if (!vd->tls.x509cert) {
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|         VNC_DEBUG("No server x509 certificate specified\n");
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|         return NULL;
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|     }
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|     if (!vd->tls.x509key) {
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|         VNC_DEBUG("No server private key specified\n");
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|         return NULL;
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|     }
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| 
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|     if ((ret = gnutls_certificate_allocate_credentials(&x509_cred)) < 0) {
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|         VNC_DEBUG("Cannot allocate credentials %s\n", gnutls_strerror(ret));
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|         return NULL;
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|     }
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|     if ((ret = gnutls_certificate_set_x509_trust_file(x509_cred,
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|                                                       vd->tls.x509cacert,
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|                                                       GNUTLS_X509_FMT_PEM)) < 0) {
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|         VNC_DEBUG("Cannot load CA certificate %s\n", gnutls_strerror(ret));
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|         gnutls_certificate_free_credentials(x509_cred);
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|         return NULL;
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|     }
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| 
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|     if ((ret = gnutls_certificate_set_x509_key_file (x509_cred,
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|                                                      vd->tls.x509cert,
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|                                                      vd->tls.x509key,
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|                                                      GNUTLS_X509_FMT_PEM)) < 0) {
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|         VNC_DEBUG("Cannot load certificate & key %s\n", gnutls_strerror(ret));
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|         gnutls_certificate_free_credentials(x509_cred);
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|         return NULL;
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|     }
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| 
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|     if (vd->tls.x509cacrl) {
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|         if ((ret = gnutls_certificate_set_x509_crl_file(x509_cred,
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|                                                         vd->tls.x509cacrl,
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|                                                         GNUTLS_X509_FMT_PEM)) < 0) {
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|             VNC_DEBUG("Cannot load CRL %s\n", gnutls_strerror(ret));
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|             gnutls_certificate_free_credentials(x509_cred);
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|             return NULL;
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|         }
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|     }
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| 
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|     gnutls_certificate_set_dh_params (x509_cred, dh_params);
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| 
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|     return x509_cred;
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| }
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| 
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| 
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| int vnc_tls_validate_certificate(struct VncState *vs)
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| {
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|     int ret;
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|     unsigned int status;
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|     const gnutls_datum_t *certs;
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|     unsigned int nCerts, i;
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|     time_t now;
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| 
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|     VNC_DEBUG("Validating client certificate\n");
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|     if ((ret = gnutls_certificate_verify_peers2 (vs->tls.session, &status)) < 0) {
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|         VNC_DEBUG("Verify failed %s\n", gnutls_strerror(ret));
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|         return -1;
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|     }
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| 
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|     if ((now = time(NULL)) == ((time_t)-1)) {
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|         return -1;
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|     }
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| 
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|     if (status != 0) {
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|         if (status & GNUTLS_CERT_INVALID)
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|             VNC_DEBUG("The certificate is not trusted.\n");
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| 
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|         if (status & GNUTLS_CERT_SIGNER_NOT_FOUND)
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|             VNC_DEBUG("The certificate hasn't got a known issuer.\n");
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| 
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|         if (status & GNUTLS_CERT_REVOKED)
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|             VNC_DEBUG("The certificate has been revoked.\n");
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| 
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|         if (status & GNUTLS_CERT_INSECURE_ALGORITHM)
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|             VNC_DEBUG("The certificate uses an insecure algorithm\n");
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| 
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|         return -1;
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|     } else {
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|         VNC_DEBUG("Certificate is valid!\n");
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|     }
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| 
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|     /* Only support x509 for now */
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|     if (gnutls_certificate_type_get(vs->tls.session) != GNUTLS_CRT_X509)
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|         return -1;
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| 
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|     if (!(certs = gnutls_certificate_get_peers(vs->tls.session, &nCerts)))
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|         return -1;
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| 
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|     for (i = 0 ; i < nCerts ; i++) {
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|         gnutls_x509_crt_t cert;
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|         VNC_DEBUG ("Checking certificate chain %d\n", i);
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|         if (gnutls_x509_crt_init (&cert) < 0)
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|             return -1;
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| 
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|         if (gnutls_x509_crt_import(cert, &certs[i], GNUTLS_X509_FMT_DER) < 0) {
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|             gnutls_x509_crt_deinit (cert);
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|             return -1;
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|         }
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| 
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|         if (gnutls_x509_crt_get_expiration_time (cert) < now) {
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|             VNC_DEBUG("The certificate has expired\n");
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|             gnutls_x509_crt_deinit (cert);
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|             return -1;
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|         }
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| 
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|         if (gnutls_x509_crt_get_activation_time (cert) > now) {
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|             VNC_DEBUG("The certificate is not yet activated\n");
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|             gnutls_x509_crt_deinit (cert);
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|             return -1;
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|         }
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| 
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|         if (gnutls_x509_crt_get_activation_time (cert) > now) {
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|             VNC_DEBUG("The certificate is not yet activated\n");
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|             gnutls_x509_crt_deinit (cert);
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|             return -1;
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|         }
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| 
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|         if (i == 0) {
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|             size_t dnameSize = 1024;
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|             vs->tls.dname = qemu_malloc(dnameSize);
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|         requery:
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|             if ((ret = gnutls_x509_crt_get_dn (cert, vs->tls.dname, &dnameSize)) != 0) {
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|                 if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
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|                     vs->tls.dname = qemu_realloc(vs->tls.dname, dnameSize);
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|                     goto requery;
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|                 }
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|                 gnutls_x509_crt_deinit (cert);
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|                 VNC_DEBUG("Cannot get client distinguished name: %s",
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|                           gnutls_strerror (ret));
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|                 return -1;
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|             }
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| 
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|             if (vs->vd->tls.x509verify) {
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|                 int allow;
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|                 if (!vs->vd->tls.acl) {
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|                     VNC_DEBUG("no ACL activated, allowing access");
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|                     gnutls_x509_crt_deinit (cert);
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|                     continue;
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|                 }
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| 
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|                 allow = qemu_acl_party_is_allowed(vs->vd->tls.acl,
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|                                                   vs->tls.dname);
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| 
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|                 VNC_DEBUG("TLS x509 ACL check for %s is %s\n",
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|                           vs->tls.dname, allow ? "allowed" : "denied");
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|                 if (!allow) {
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|                     gnutls_x509_crt_deinit (cert);
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|                     return -1;
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|                 }
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|             }
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|         }
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| 
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|         gnutls_x509_crt_deinit (cert);
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|     }
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| 
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|     return 0;
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| }
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| 
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| 
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| int vnc_tls_client_setup(struct VncState *vs,
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|                          int needX509Creds) {
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|     static const int cert_type_priority[] = { GNUTLS_CRT_X509, 0 };
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|     static const int protocol_priority[]= { GNUTLS_TLS1_1, GNUTLS_TLS1_0, GNUTLS_SSL3, 0 };
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|     static const int kx_anon[] = {GNUTLS_KX_ANON_DH, 0};
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|     static const int kx_x509[] = {GNUTLS_KX_DHE_DSS, GNUTLS_KX_RSA, GNUTLS_KX_DHE_RSA, GNUTLS_KX_SRP, 0};
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| 
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|     VNC_DEBUG("Do TLS setup\n");
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|     if (vnc_tls_initialize() < 0) {
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|         VNC_DEBUG("Failed to init TLS\n");
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|         vnc_client_error(vs);
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|         return -1;
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|     }
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|     if (vs->tls.session == NULL) {
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|         if (gnutls_init(&vs->tls.session, GNUTLS_SERVER) < 0) {
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|             vnc_client_error(vs);
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|             return -1;
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|         }
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| 
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|         if (gnutls_set_default_priority(vs->tls.session) < 0) {
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|             gnutls_deinit(vs->tls.session);
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|             vs->tls.session = NULL;
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|             vnc_client_error(vs);
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|             return -1;
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|         }
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| 
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|         if (gnutls_kx_set_priority(vs->tls.session, needX509Creds ? kx_x509 : kx_anon) < 0) {
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|             gnutls_deinit(vs->tls.session);
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|             vs->tls.session = NULL;
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|             vnc_client_error(vs);
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|             return -1;
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|         }
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| 
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|         if (gnutls_certificate_type_set_priority(vs->tls.session, cert_type_priority) < 0) {
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|             gnutls_deinit(vs->tls.session);
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|             vs->tls.session = NULL;
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|             vnc_client_error(vs);
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|             return -1;
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|         }
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| 
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|         if (gnutls_protocol_set_priority(vs->tls.session, protocol_priority) < 0) {
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|             gnutls_deinit(vs->tls.session);
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|             vs->tls.session = NULL;
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|             vnc_client_error(vs);
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|             return -1;
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|         }
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| 
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|         if (needX509Creds) {
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|             gnutls_certificate_server_credentials x509_cred = vnc_tls_initialize_x509_cred(vs->vd);
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|             if (!x509_cred) {
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|                 gnutls_deinit(vs->tls.session);
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|                 vs->tls.session = NULL;
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|                 vnc_client_error(vs);
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|                 return -1;
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|             }
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|             if (gnutls_credentials_set(vs->tls.session, GNUTLS_CRD_CERTIFICATE, x509_cred) < 0) {
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|                 gnutls_deinit(vs->tls.session);
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|                 vs->tls.session = NULL;
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|                 gnutls_certificate_free_credentials(x509_cred);
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|                 vnc_client_error(vs);
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|                 return -1;
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|             }
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|             if (vs->vd->tls.x509verify) {
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|                 VNC_DEBUG("Requesting a client certificate\n");
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|                 gnutls_certificate_server_set_request (vs->tls.session, GNUTLS_CERT_REQUEST);
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|             }
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| 
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|         } else {
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|             gnutls_anon_server_credentials anon_cred = vnc_tls_initialize_anon_cred();
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|             if (!anon_cred) {
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|                 gnutls_deinit(vs->tls.session);
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|                 vs->tls.session = NULL;
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|                 vnc_client_error(vs);
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|                 return -1;
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|             }
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|             if (gnutls_credentials_set(vs->tls.session, GNUTLS_CRD_ANON, anon_cred) < 0) {
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|                 gnutls_deinit(vs->tls.session);
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|                 vs->tls.session = NULL;
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|                 gnutls_anon_free_server_credentials(anon_cred);
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|                 vnc_client_error(vs);
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|                 return -1;
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|             }
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|         }
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| 
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|         gnutls_transport_set_ptr(vs->tls.session, (gnutls_transport_ptr_t)vs);
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|         gnutls_transport_set_push_function(vs->tls.session, vnc_tls_push);
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|         gnutls_transport_set_pull_function(vs->tls.session, vnc_tls_pull);
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|     }
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|     return 0;
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| }
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| 
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| 
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| void vnc_tls_client_cleanup(struct VncState *vs)
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| {
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|     if (vs->tls.session) {
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|         gnutls_deinit(vs->tls.session);
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|         vs->tls.session = NULL;
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|     }
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|     vs->tls.wiremode = VNC_WIREMODE_CLEAR;
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|     free(vs->tls.dname);
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| }
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| 
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| 
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| 
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| static int vnc_set_x509_credential(VncDisplay *vd,
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|                                    const char *certdir,
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|                                    const char *filename,
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|                                    char **cred,
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|                                    int ignoreMissing)
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| {
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|     struct stat sb;
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| 
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|     if (*cred) {
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|         qemu_free(*cred);
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|         *cred = NULL;
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|     }
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| 
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|     *cred = qemu_malloc(strlen(certdir) + strlen(filename) + 2);
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| 
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|     strcpy(*cred, certdir);
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|     strcat(*cred, "/");
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|     strcat(*cred, filename);
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| 
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|     VNC_DEBUG("Check %s\n", *cred);
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|     if (stat(*cred, &sb) < 0) {
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|         qemu_free(*cred);
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|         *cred = NULL;
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|         if (ignoreMissing && errno == ENOENT)
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|             return 0;
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|         return -1;
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|     }
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| 
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|     return 0;
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| }
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| 
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| 
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| int vnc_tls_set_x509_creds_dir(VncDisplay *vd,
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|                                const char *certdir)
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| {
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|     if (vnc_set_x509_credential(vd, certdir, X509_CA_CERT_FILE, &vd->tls.x509cacert, 0) < 0)
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|         goto cleanup;
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|     if (vnc_set_x509_credential(vd, certdir, X509_CA_CRL_FILE, &vd->tls.x509cacrl, 1) < 0)
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|         goto cleanup;
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|     if (vnc_set_x509_credential(vd, certdir, X509_SERVER_CERT_FILE, &vd->tls.x509cert, 0) < 0)
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|         goto cleanup;
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|     if (vnc_set_x509_credential(vd, certdir, X509_SERVER_KEY_FILE, &vd->tls.x509key, 0) < 0)
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|         goto cleanup;
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| 
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|     return 0;
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| 
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|  cleanup:
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|     qemu_free(vd->tls.x509cacert);
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|     qemu_free(vd->tls.x509cacrl);
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|     qemu_free(vd->tls.x509cert);
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|     qemu_free(vd->tls.x509key);
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|     vd->tls.x509cacert = vd->tls.x509cacrl = vd->tls.x509cert = vd->tls.x509key = NULL;
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|     return -1;
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| }
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| 
 |