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TLS support for VNC Websockets
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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>
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@thardeck
thardeck authored and Anthony Liguori committed May 3, 2013
1 parent 8f3b664 commit 0057a0d
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Showing 6 changed files with 178 additions and 42 deletions.
2 changes: 2 additions & 0 deletions qemu-options.hx
View file
Expand Up @@ -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

Expand Down
61 changes: 39 additions & 22 deletions ui/vnc-tls.c
View file
Expand Up @@ -334,73 +334,82 @@ 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;
}

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;
}
Expand All @@ -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 */
}


Expand Down
63 changes: 63 additions & 0 deletions ui/vnc-ws.c
View file
Expand Up @@ -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;
Expand Down
3 changes: 3 additions & 0 deletions ui/vnc-ws.h
View file
Expand Up @@ -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);
Expand Down
86 changes: 67 additions & 19 deletions ui/vnc.c
View file
Expand Up @@ -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
Expand All @@ -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());
}
Expand Down Expand Up @@ -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
Expand All @@ -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());
}
Expand Down Expand Up @@ -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 */
{
Expand Down
5 changes: 4 additions & 1 deletion ui/vnc.h
View file
Expand Up @@ -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;

Expand Down

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