Commit 51941e46 authored by Daniel P. Berrangé's avatar Daniel P. Berrangé Committed by Gerd Hoffmann
Browse files

ui: enforce TLS when using websockets server 



When TLS is required, the primary VNC server considers it to be
mandatory. ie the server admin decides whether or not TLS is used,
and the client has to comply with this decision. The websockets
server, however, treated it as optional, allowing non-TLS clients
to connect to a server which had setup TLS. Thus enabling websockets
lowers the security of the VNC server leaving the admin no way to
enforce use of TLS.

This removes the code that allows non-TLS fallback in the websockets
server, so that if TLS is requested for VNC it is now mandatory for
both the primary VNC server and the websockets VNC server.

Signed-off-by: default avatarDaniel P. Berrange <berrange@redhat.com>
Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent f9148c8a

ui/vnc-ws.c

+7 −24
Original line number Diff line number Diff line
@@ -24,8 +24,6 @@ 
#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);
@@ -53,33 +51,18 @@ static int vncws_start_tls_handshake(struct VncState *vs) 
    return 0;

}



static void vncws_tls_handshake_io(void *opaque)

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);

    if (!vs->tls.session) {

        VNC_DEBUG("TLS Websocket setup\n");

        if (vnc_tls_client_setup(vs, vs->vd->tls.x509cert != NULL) < 0) {

            return;

        }

    } else {

        qemu_set_fd_handler2(vs->csock, NULL, vncws_handshake_read, NULL, vs);

    }

    VNC_DEBUG("Handshake IO continue\n");

    vncws_start_tls_handshake(vs);

}

#endif /* CONFIG_VNC_TLS */

ui/vnc-ws.h

+1 −1
Original line number Diff line number Diff line
@@ -75,7 +75,7 @@ enum { 
};



#ifdef CONFIG_VNC_TLS

void vncws_tls_handshake_peek(void *opaque);

void vncws_tls_handshake_io(void *opaque);

#endif /* CONFIG_VNC_TLS */

void vncws_handshake_read(void *opaque);

long vnc_client_write_ws(VncState *vs);

ui/vnc.c

+1 −1
Original line number Diff line number Diff line
@@ -3036,7 +3036,7 @@ static void vnc_connect(VncDisplay *vd, int csock, 
        vs->websocket = 1;

#ifdef CONFIG_VNC_TLS

        if (vd->ws_tls) {

            qemu_set_fd_handler2(vs->csock, NULL, vncws_tls_handshake_peek,

            qemu_set_fd_handler2(vs->csock, NULL, vncws_tls_handshake_io,

                                 NULL, vs);

        } else

#endif /* CONFIG_VNC_TLS */