Re: [Qemu-devel] PATCH 3/8: VNC password authentication

[Anthony Liguori <anthony@codemonkey.ws>]

Daniel P. Berrange wrote:
> On Tue, Jul 31, 2007 at 08:46:49PM -0500, Anthony Liguori wrote:
>   
>> Daniel P. Berrange wrote:
>>     
>>> This patch introduces support for VNC protocols upto 3.8 and with
>>> it, support for password based authentication. VNC's password based
>>> authentication is not entirely secure, but it is a standard and the
>>> RFB spec requires that all clients support it. The password can be
>>> provided by using the monitor 'change vnc :1' and it will prompt for
>>> a password to be entered. Passwords have upto 8 letters of context.
>>> Pressing 'enter' without entering any characters disables password
>>> auth in the server. NB, we need a custom copy of d3des here because
>>> VNC uses a 'special' modification of the algorithm. This d3des code
>>> is public domain & in all other VNC servers & clients.
>>>  
>>>       
>> I think it may be better to have a command to explicitly set the vnc 
>> password.  Issuing "change vnc :1" just to change the password is a 
>> little awkward IMHO.
>>     
>
> Ok I'll add a separate command for that - any preference for naming.
> I thought about 'change vncpassword', but the 'change' command requires
> 2 args and we'd only have 1 here.  Or if we think there may be other
> devices/drivers which will have passwords in the future we could have
> 'change password vnc' as the command. 
>   

I don't really have that strong of preference.

Regards,

Anthony Liguori

>>> -
>>> -    vnc_write_u32(vs, 1); /* None */
>>> -    vnc_flush(vs);
>>> -
>>> -    vnc_read_when(vs, protocol_client_init, 1);
>>> +    VNC_DEBUG("Client request protocol version %d.%d\n", vs->major, 
>>> vs->minor);
>>> +    if (vs->major != 3 ||
>>> +	(vs->minor != 3 &&
>>> +	 vs->minor != 7 &&
>>> +	 vs->minor != 8)) {
>>> +	VNC_DEBUG("Unsupported client version\n");
>>> +	vnc_write_u32(vs, VNC_AUTH_INVALID);
>>> +	vnc_flush(vs);
>>> +	vnc_client_error(vs);
>>> +	return 0;
>>> +    }
>>>  
>>>       
>> A very popular VNC client uses 3.5 as the protocol version.  I believe 
>> the specification requires that 3.5 be treated at 3.3 because of that.
>>     
>
> Good point. I'll add support for that.
>
> Regards,
> Dan.
>