TLS support for VNC Websockets

Added TLS support to the VNC QEMU Websockets implementation.
VNC-TLS needs to be enabled for this feature to be used.

The required certificates are specified as in case of VNC-TLS
with the VNC parameter "x509=<path>".

If the server certificate isn't signed by a rooth authority it needs to
be manually imported in the browser because at least in case of Firefox
and Chrome there is no user dialog, the connection just gets canceled.

As a side note VEncrypt over Websocket doesn't work atm because TLS can't
be stacked in the current implementation. (It also didn't work before)
Nevertheless to my knowledge there is no HTML 5 VNC client which supports
it and the Websocket connection can be encrypted with regular TLS now so
it should be fine for most use cases.

Signed-off-by: Tim Hardeck <thardeck@suse.de>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Message-id: 1366727581-5772-1-git-send-email-thardeck@suse.de
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/qemu-options.hx b/qemu-options.hx
index e86cc2439ddffa427ef20336b952dca27f3bc003..fb62b75ccbb4b5d94d111da9e153743ce3ce0c9c 100644 (file)
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1127,6 +1127,8 @@ By definition the Websocket port is 5700+@var{display}. If @var{host} is
 specified connections will only be allowed from this host.
 As an alternative the Websocket port could be specified by using
 @code{websocket}=@var{port}.
+TLS encryption for the Websocket connection is supported if the required
+certificates are specified with the VNC option @option{x509}.
 
 @item password
 

diff --git a/ui/vnc-tls.c b/ui/vnc-tls.c
index 8d4cc8e47cf281efcb6ec61ac9ebbc1398dd5c68..50275de64f712b0038a9b3156eeb05e79973e1a9 100644 (file)
--- a/ui/vnc-tls.c
+++ b/ui/vnc-tls.c
@@ -334,29 +334,38 @@ static int vnc_set_gnutls_priority(gnutls_session_t s, int x509)
 
 int vnc_tls_client_setup(struct VncState *vs,
                          int needX509Creds) {
+    VncStateTLS *tls;
 
     VNC_DEBUG("Do TLS setup\n");
+#ifdef CONFIG_VNC_WS
+    if (vs->websocket) {
+        tls = &vs->ws_tls;
+    } else
+#endif /* CONFIG_VNC_WS */
+    {
+        tls = &vs->tls;
+    }
     if (vnc_tls_initialize() < 0) {
         VNC_DEBUG("Failed to init TLS\n");
         vnc_client_error(vs);
         return -1;
     }
-    if (vs->tls.session == NULL) {
-        if (gnutls_init(&vs->tls.session, GNUTLS_SERVER) < 0) {
+    if (tls->session == NULL) {
+        if (gnutls_init(&tls->session, GNUTLS_SERVER) < 0) {
             vnc_client_error(vs);
             return -1;
         }
 
-        if (gnutls_set_default_priority(vs->tls.session) < 0) {
-            gnutls_deinit(vs->tls.session);
-            vs->tls.session = NULL;
+        if (gnutls_set_default_priority(tls->session) < 0) {
+            gnutls_deinit(tls->session);
+            tls->session = NULL;
             vnc_client_error(vs);
             return -1;
         }
 
-        if (vnc_set_gnutls_priority(vs->tls.session, needX509Creds) < 0) {
-            gnutls_deinit(vs->tls.session);
-            vs->tls.session = NULL;
+        if (vnc_set_gnutls_priority(tls->session, needX509Creds) < 0) {
+            gnutls_deinit(tls->session);
+            tls->session = NULL;
             vnc_client_error(vs);
             return -1;
         }
@@ -364,43 +373,43 @@ int vnc_tls_client_setup(struct VncState *vs,
         if (needX509Creds) {
             gnutls_certificate_server_credentials x509_cred = vnc_tls_initialize_x509_cred(vs->vd);
             if (!x509_cred) {
-                gnutls_deinit(vs->tls.session);
-                vs->tls.session = NULL;
+                gnutls_deinit(tls->session);
+                tls->session = NULL;
                 vnc_client_error(vs);
                 return -1;
             }
-            if (gnutls_credentials_set(vs->tls.session, GNUTLS_CRD_CERTIFICATE, x509_cred) < 0) {
-                gnutls_deinit(vs->tls.session);
-                vs->tls.session = NULL;
+            if (gnutls_credentials_set(tls->session, GNUTLS_CRD_CERTIFICATE, x509_cred) < 0) {
+                gnutls_deinit(tls->session);
+                tls->session = NULL;
                 gnutls_certificate_free_credentials(x509_cred);
                 vnc_client_error(vs);
                 return -1;
             }
             if (vs->vd->tls.x509verify) {
                 VNC_DEBUG("Requesting a client certificate\n");
-                gnutls_certificate_server_set_request (vs->tls.session, GNUTLS_CERT_REQUEST);
+                gnutls_certificate_server_set_request (tls->session, GNUTLS_CERT_REQUEST);
             }
 
         } else {
             gnutls_anon_server_credentials_t anon_cred = vnc_tls_initialize_anon_cred();
             if (!anon_cred) {
-                gnutls_deinit(vs->tls.session);
-                vs->tls.session = NULL;
+                gnutls_deinit(tls->session);
+                tls->session = NULL;
                 vnc_client_error(vs);
                 return -1;
             }
-            if (gnutls_credentials_set(vs->tls.session, GNUTLS_CRD_ANON, anon_cred) < 0) {
-                gnutls_deinit(vs->tls.session);
-                vs->tls.session = NULL;
+            if (gnutls_credentials_set(tls->session, GNUTLS_CRD_ANON, anon_cred) < 0) {
+                gnutls_deinit(tls->session);
+                tls->session = NULL;
                 gnutls_anon_free_server_credentials(anon_cred);
                 vnc_client_error(vs);
                 return -1;
             }
         }
 
-        gnutls_transport_set_ptr(vs->tls.session, (gnutls_transport_ptr_t)vs);
-        gnutls_transport_set_push_function(vs->tls.session, vnc_tls_push);
-        gnutls_transport_set_pull_function(vs->tls.session, vnc_tls_pull);
+        gnutls_transport_set_ptr(tls->session, (gnutls_transport_ptr_t)vs);
+        gnutls_transport_set_push_function(tls->session, vnc_tls_push);
+        gnutls_transport_set_pull_function(tls->session, vnc_tls_pull);
     }
     return 0;
 }
@@ -414,6 +423,14 @@ void vnc_tls_client_cleanup(struct VncState *vs)
     }
     vs->tls.wiremode = VNC_WIREMODE_CLEAR;
     g_free(vs->tls.dname);
+#ifdef CONFIG_VNC_WS
+    if (vs->ws_tls.session) {
+        gnutls_deinit(vs->ws_tls.session);
+        vs->ws_tls.session = NULL;
+    }
+    vs->ws_tls.wiremode = VNC_WIREMODE_CLEAR;
+    g_free(vs->ws_tls.dname);
+#endif /* CONFIG_VNC_WS */
 }
 
 

diff --git a/ui/vnc-ws.c b/ui/vnc-ws.c
index 3e3020916ce70d7102b4bfb81c52a34e864a1388..df89315733aab42bfc391d5f6309e811bc2b3fa5 100644 (file)
--- a/ui/vnc-ws.c
+++ b/ui/vnc-ws.c
@@ -20,6 +20,69 @@
 
 #include "vnc.h"
 
+#ifdef CONFIG_VNC_TLS
+#include "qemu/sockets.h"
+
+static void vncws_tls_handshake_io(void *opaque);
+
+static int vncws_start_tls_handshake(struct VncState *vs)
+{
+    int ret = gnutls_handshake(vs->ws_tls.session);
+
+    if (ret < 0) {
+        if (!gnutls_error_is_fatal(ret)) {
+            VNC_DEBUG("Handshake interrupted (blocking)\n");
+            if (!gnutls_record_get_direction(vs->ws_tls.session)) {
+                qemu_set_fd_handler(vs->csock, vncws_tls_handshake_io,
+                                    NULL, vs);
+            } else {
+                qemu_set_fd_handler(vs->csock, NULL, vncws_tls_handshake_io,
+                                    vs);
+            }
+            return 0;
+        }
+        VNC_DEBUG("Handshake failed %s\n", gnutls_strerror(ret));
+        vnc_client_error(vs);
+        return -1;
+    }
+
+    VNC_DEBUG("Handshake done, switching to TLS data mode\n");
+    vs->ws_tls.wiremode = VNC_WIREMODE_TLS;
+    qemu_set_fd_handler2(vs->csock, NULL, vncws_handshake_read, NULL, vs);
+
+    return 0;
+}
+
+static void vncws_tls_handshake_io(void *opaque)
+{
+    struct VncState *vs = (struct VncState *)opaque;
+
+    VNC_DEBUG("Handshake IO continue\n");
+    vncws_start_tls_handshake(vs);
+}
+
+void vncws_tls_handshake_peek(void *opaque)
+{
+    VncState *vs = opaque;
+    long ret;
+
+    if (!vs->ws_tls.session) {
+        char peek[4];
+        ret = qemu_recv(vs->csock, peek, sizeof(peek), MSG_PEEK);
+        if (ret && (strncmp(peek, "\x16", 1) == 0
+                    || strncmp(peek, "\x80", 1) == 0)) {
+            VNC_DEBUG("TLS Websocket connection recognized");
+            vnc_tls_client_setup(vs, 1);
+            vncws_start_tls_handshake(vs);
+        } else {
+            vncws_handshake_read(vs);
+        }
+    } else {
+        qemu_set_fd_handler2(vs->csock, NULL, vncws_handshake_read, NULL, vs);
+    }
+}
+#endif /* CONFIG_VNC_TLS */
+
 void vncws_handshake_read(void *opaque)
 {
     VncState *vs = opaque;

diff --git a/ui/vnc-ws.h b/ui/vnc-ws.h
index 039a58765cafca60866c12fd01d941f945b89610..95c1b0aeae5239d6e1101232d05bcdd99c3cce0d 100644 (file)
--- a/ui/vnc-ws.h
+++ b/ui/vnc-ws.h
@@ -74,6 +74,9 @@ enum {
     WS_OPCODE_PONG = 0xA
 };
 
+#ifdef CONFIG_VNC_TLS
+void vncws_tls_handshake_peek(void *opaque);
+#endif /* CONFIG_VNC_TLS */
 void vncws_handshake_read(void *opaque);
 long vnc_client_write_ws(VncState *vs);
 long vnc_client_read_ws(VncState *vs);

diff --git a/ui/vnc.c b/ui/vnc.c
index b90281b77bdad56c6b1143da89b712cdb40fcf1f..89108de223003bd291b2c509ebbb91c93c78a83f 100644 (file)
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -1111,6 +1111,23 @@ void vnc_client_error(VncState *vs)
     vnc_disconnect_start(vs);
 }
 
+#ifdef CONFIG_VNC_TLS
+static long vnc_client_write_tls(gnutls_session_t *session,
+                                 const uint8_t *data,
+                                 size_t datalen)
+{
+    long ret = gnutls_write(*session, data, datalen);
+    if (ret < 0) {
+        if (ret == GNUTLS_E_AGAIN) {
+            errno = EAGAIN;
+        } else {
+            errno = EIO;
+        }
+        ret = -1;
+    }
+    return ret;
+}
+#endif /* CONFIG_VNC_TLS */
 
 /*
  * Called to write a chunk of data to the client socket. The data may
@@ -1132,17 +1149,20 @@ long vnc_client_write_buf(VncState *vs, const uint8_t *data, size_t datalen)
     long ret;
 #ifdef CONFIG_VNC_TLS
     if (vs->tls.session) {
-        ret = gnutls_write(vs->tls.session, data, datalen);
-        if (ret < 0) {
-            if (ret == GNUTLS_E_AGAIN)
-                errno = EAGAIN;
-            else
-                errno = EIO;
-            ret = -1;
+        ret = vnc_client_write_tls(&vs->tls.session, data, datalen);
+    } else {
+#ifdef CONFIG_VNC_WS
+        if (vs->ws_tls.session) {
+            ret = vnc_client_write_tls(&vs->ws_tls.session, data, datalen);
+        } else
+#endif /* CONFIG_VNC_WS */
+#endif /* CONFIG_VNC_TLS */
+        {
+            ret = send(vs->csock, (const void *)data, datalen, 0);
         }
-    } else
+#ifdef CONFIG_VNC_TLS
+    }
 #endif /* CONFIG_VNC_TLS */
-        ret = send(vs->csock, (const void *)data, datalen, 0);
     VNC_DEBUG("Wrote wire %p %zd -> %ld\n", data, datalen, ret);
     return vnc_client_io_error(vs, ret, socket_error());
 }
@@ -1240,6 +1260,22 @@ void vnc_read_when(VncState *vs, VncReadEvent *func, size_t expecting)
     vs->read_handler_expect = expecting;
 }
 
+#ifdef CONFIG_VNC_TLS
+static long vnc_client_read_tls(gnutls_session_t *session, uint8_t *data,
+                                size_t datalen)
+{
+    long ret = gnutls_read(*session, data, datalen);
+    if (ret < 0) {
+        if (ret == GNUTLS_E_AGAIN) {
+            errno = EAGAIN;
+        } else {
+            errno = EIO;
+        }
+        ret = -1;
+    }
+    return ret;
+}
+#endif /* CONFIG_VNC_TLS */
 
 /*
  * Called to read a chunk of data from the client socket. The data may
@@ -1261,17 +1297,20 @@ long vnc_client_read_buf(VncState *vs, uint8_t *data, size_t datalen)
     long ret;
 #ifdef CONFIG_VNC_TLS
     if (vs->tls.session) {
-        ret = gnutls_read(vs->tls.session, data, datalen);
-        if (ret < 0) {
-            if (ret == GNUTLS_E_AGAIN)
-                errno = EAGAIN;
-            else
-                errno = EIO;
-            ret = -1;
+        ret = vnc_client_read_tls(&vs->tls.session, data, datalen);
+    } else {
+#ifdef CONFIG_VNC_WS
+        if (vs->ws_tls.session) {
+            ret = vnc_client_read_tls(&vs->ws_tls.session, data, datalen);
+        } else
+#endif /* CONFIG_VNC_WS */
+#endif /* CONFIG_VNC_TLS */
+        {
+            ret = qemu_recv(vs->csock, data, datalen, 0);
         }
-    } else
+#ifdef CONFIG_VNC_TLS
+    }
 #endif /* CONFIG_VNC_TLS */
-        ret = qemu_recv(vs->csock, data, datalen, 0);
     VNC_DEBUG("Read wire %p %zd -> %ld\n", data, datalen, ret);
     return vnc_client_io_error(vs, ret, socket_error());
 }
@@ -2761,7 +2800,16 @@ static void vnc_connect(VncDisplay *vd, int csock, int skipauth, bool websocket)
 #ifdef CONFIG_VNC_WS
     if (websocket) {
         vs->websocket = 1;
-        qemu_set_fd_handler2(vs->csock, NULL, vncws_handshake_read, NULL, vs);
+#ifdef CONFIG_VNC_TLS
+        if (vd->tls.x509cert) {
+            qemu_set_fd_handler2(vs->csock, NULL, vncws_tls_handshake_peek,
+                                 NULL, vs);
+        } else
+#endif /* CONFIG_VNC_TLS */
+        {
+            qemu_set_fd_handler2(vs->csock, NULL, vncws_handshake_read,
+                                 NULL, vs);
+        }
     } else
 #endif /* CONFIG_VNC_WS */
     {

diff --git a/ui/vnc.h b/ui/vnc.h
index fea39adcc7c8c122899e4e63f7fa75d2d6b0d3ff..6e9921387f4deccf48296853febe480cc67021b3 100644 (file)
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -276,9 +276,12 @@ struct VncState
     VncStateSASL sasl;
 #endif
 #ifdef CONFIG_VNC_WS
+#ifdef CONFIG_VNC_TLS
+    VncStateTLS ws_tls;
+#endif /* CONFIG_VNC_TLS */
     bool encode_ws;
     bool websocket;
-#endif
+#endif /* CONFIG_VNC_WS */
 
     QObject *info;