[Qemu-devel] Re: [PATCH] vnc: Fix password expiration through 'change vnc ""'

[Daniel P. Berrange]

On Mon, Feb 14, 2011 at 06:10:04AM -0600, Anthony Liguori wrote:
> On 02/14/2011 04:57 AM, Gerd Hoffmann wrote:
> >On 01/31/11 21:43, Anthony Liguori wrote:
> >>commit 52c18be9e99dabe295321153fda7fce9f76647ac introduced a
> >>regression in the
> >>change vnc password command that changed the behavior of setting the VNC
> >>password to an empty string from disabling login to disabling
> >>authentication.
> >>
> >>This commit refactors the code to eliminate this overloaded semantics in
> >>vnc_display_password and instead introduces the
> >>vnc_display_disable_login.   The
> >>monitor implementation then determines the behavior of an empty
> >>or missing
> >>string.
> >
> >Hmm, now about simply never ever changing vs->auth?
> 
> If auth is none and you do a vnc change password "" then if we don't
> set vs->auth to vnc, it won't have the desired effect.  I really
> dislike the semantics of this command but that was a past mistake.

Actually blindly setting 'vs->auth' to 'vnc' is also a security flaw.
If using the VeNCrypt security method, then 'vs->auth' will be VENCRYPT
and the 'vs->subauth' will possibly indicate the 'VNC' sub-auth scheme.
So we really do want the change password command to leave 'vs->auth'
alone completely - just change the password string, with no side effects
on auth methods. If an app intends to use the change password command
it will have already launched QEMU with neccessary -vnc flags to set the
desired vs->auth and vs->subauth methods.

Regards,
Daniel
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