Switch VNC server over to using the QCryptoTLSSession object
for the TLS session. This removes the direct use of gnutls
from the VNC server code. It also removes most knowledge
about TLS certificate handling from the VNC server code.
This has the nice effect that all the CONFIG_VNC_TLS
conditionals go away and the user gets an actual error
message when requesting TLS instead of it being silently
ignored.
With this change, the existing configuration options for
enabling TLS with -vnc are deprecated.
Old syntax for anon-DH credentials:
-vnc hostname:0,tls
New syntax:
-object tls-creds-anon,id=tls0,endpoint=server \
-vnc hostname:0,tls-creds=tls0
Old syntax for x509 credentials, no client certs:
-vnc hostname:0,tls,x509=/path/to/certs
New syntax:
-object tls-creds-x509,id=tls0,dir=/path/to/certs,endpoint=server,verify-peer=no \
-vnc hostname:0,tls-creds=tls0
Old syntax for x509 credentials, requiring client certs:
-vnc hostname:0,tls,x509verify=/path/to/certs
New syntax:
-object tls-creds-x509,id=tls0,dir=/path/to/certs,endpoint=server,verify-peer=yes \
-vnc hostname:0,tls-creds=tls0
This aligns VNC with the way TLS credentials are to be
configured in the future for chardev, nbd and migration
backends. It also has the benefit that the same TLS
credentials can be shared across multiple VNC server
instances, if desired.
If someone uses the deprecated syntax, it will internally
result in the creation of a 'tls-creds' object with an ID
based on the VNC server ID. This allows backwards compat
with the CLI syntax, while still deleting all the original
TLS code from the VNC server.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Remove the direct use of gnutls for hash processing in the
websockets code, in favour of using the crypto APIs. This
allows the websockets code to be built unconditionally
removing countless conditional checks from the VNC code.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-9-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The logic for decoding websocket frames wants to fully
decode the frame header and payload, before allowing the
VNC server to see any of the payload data. There is no
size limit on websocket payloads, so this allows a
malicious network client to consume 2^64 bytes in memory
in QEMU. It can trigger this denial of service before
the VNC server even performs any authentication.
The fix is to decode the header, and then incrementally
decode the payload data as it is needed. With this fix
the websocket decoder will allow at most 4k of data to
be buffered before decoding and processing payload.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
[ kraxel: fix frequent spurious disconnects, suggested by Peter Maydell ]
@@ -361,7 +361,7 @@ int vncws_decode_frame_payload(Buffer *input,
- *payload_size = input->offset;
+ *payload_size = *payload_remain;
[ kraxel: fix 32bit build ]
@@ -306,7 +306,7 @@ struct VncState
- uint64_t ws_payload_remain;
+ size_t ws_payload_remain;
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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>
This patch adds basic Websocket Protocol version 13 - RFC 6455 - support
to QEMU VNC. Binary encoding support on the client side is mandatory.
Because of the GnuTLS requirement the Websockets implementation is
optional (--enable-vnc-ws).
To activate Websocket support the VNC option "websocket"is used, for
example "-vnc :0,websocket".
The listen port for Websocket connections is (5700 + display) so if
QEMU VNC is started with :0 the Websocket port would be 5700.
As an alternative the Websocket port could be manually specified by
using ",websocket=<port>" instead.
Parts of the implementation base on Anthony Liguori's QEMU Websocket
patch from 2010 and on Joel Martin's LibVNC Websocket implementation.
Signed-off-by: Tim Hardeck <thardeck@suse.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
