ui: convert VNC server to use QCryptoTLSSession

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>

1 files changed, 26 insertions, 2 deletions

diff --git a/qemu-options.hx b/qemu-options.hx
index 3f2e25b..7e147b8 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1217,8 +1217,9 @@ 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}.
+If no TLS credentials are provided, the websocket connection runs in
+unencrypted mode. If TLS credentials are provided, the websocket connection
+requires encrypted client connections.
 
 @item password
 
@@ -1239,6 +1240,20 @@ date and time).
 You can also use keywords "now" or "never" for the expiration time to
 allow <protocol> password to expire immediately or never expire.
 
+@item tls-creds=@var{ID}
+
+Provides the ID of a set of TLS credentials to use to secure the
+VNC server. They will apply to both the normal VNC server socket
+and the websocket socket (if enabled). Setting TLS credentials
+will cause the VNC server socket to enable the VeNCrypt auth
+mechanism.  The credentials should have been previously created
+using the @option{-object tls-creds} argument.
+
+The @option{tls-creds} parameter obsoletes the @option{tls},
+@option{x509}, and @option{x509verify} options, and as such
+it is not permitted to set both new and old type options at
+the same time.
+
 @item tls
 
 Require that client use TLS when communicating with the VNC server. This
@@ -1246,6 +1261,9 @@ uses anonymous TLS credentials so is susceptible to a man-in-the-middle
 attack. It is recommended that this option be combined with either the
 @option{x509} or @option{x509verify} options.
 
+This option is now deprecated in favor of using the @option{tls-creds}
+argument.
+
 @item x509=@var{/path/to/certificate/dir}
 
 Valid if @option{tls} is specified. Require that x509 credentials are used
@@ -1255,6 +1273,9 @@ to provide authentication of the client when this is used. The path following
 this option specifies where the x509 certificates are to be loaded from.
 See the @ref{vnc_security} section for details on generating certificates.
 
+This option is now deprecated in favour of using the @option{tls-creds}
+argument.
+
 @item x509verify=@var{/path/to/certificate/dir}
 
 Valid if @option{tls} is specified. Require that x509 credentials are used
@@ -1268,6 +1289,9 @@ path following this option specifies where the x509 certificates are to
 be loaded from. See the @ref{vnc_security} section for details on generating
 certificates.
 
+This option is now deprecated in favour of using the @option{tls-creds}
+argument.
+
 @item sasl
 
 Require that the client use SASL to authenticate with the VNC server.