Re: [Qemu-ppc] [PATCH v2] spapr-rtas: add ibm, get-vpd RTAS interface

[David Gibson]

On Mon, Feb 25, 2019 at 08:20:09PM -0300, Murilo Opsfelder Araujo wrote:
> Hi, Maxiwell.
> 
> On Mon, Feb 25, 2019 at 01:23:25PM -0300, Maxiwell S. Garcia wrote:
> > This adds a handler for ibm,get-vpd RTAS calls, allowing pseries
> > guest to collect host information. It is disabled by default to
> > avoid unwanted information leakage. To enable it, use:
> > ‘-M pseries,vpd-export=on’
> 
> The patch for setting host-serial and host-model already landed Gibson's
> ppc-for-4.0 branch:
> 
>   commit 9e584f45868f6945c1282c938278038cba0e4af2
>   Author: Prasad J Pandit <address@hidden>
>   Date:   Mon Feb 18 23:43:49 2019 +0530
> 
>       ppc: add host-serial and host-model machine attributes (CVE-2019-8934)
> 
> 
> QEMU should only return host-serial and host-model from the host if the
> following combination of parameters are provided:
> 
>   -M host-serial=passthrough,host-model=passthrough,vpd-export=on
> 
> If host-serial or host-model are set with a user-string, ibm,get-vpd should
> honor these values and return them, not exposing host information by accident.
> 
> I'm not even sure if we need vpd-export=<bool> setting. Its logic could be
> derived from the presence of host-serial=passthrough and 
> host-model=passthrough
> options.
> 
> What do you think?

That's an excellent point - I hadn't thought through the fact that
this is the same information exposed by those properties.  I do indeed
think that exposing the same information set in those properties - and
thereby avoiding the new machine option - would be a better plan.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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