Re: [Xen-devel] PV audio drivers for Linux

["Ughreja, Rakesh A" <rakesh.a.ughreja@xxxxxxxxx>]

>-----Original Message-----
>From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>Sent: Wednesday, January 18, 2017 3:39 PM
>To: Ughreja, Rakesh A <rakesh.a.ughreja@xxxxxxxxx>
>Cc: xen-devel@xxxxxxxxxxxxx
>Subject: Re: [Xen-devel] PV audio drivers for Linux
>
>>>> On 17.01.17 at 19:01, <rakesh.a.ughreja@xxxxxxxxx> wrote:
>> When the buffer is allocated using __get_free_pages() on the DOM0
>> OS, I am able to grant the access using gnttab_grant_foreign_access()
>> to DOM1 as well as I am able to map it in the DOM1 virtual space
>> using xenbus_map_ring_valloc().
>
>A more general remark here: The direction you do the granting is at
>least unusual, and likely to have security implications. It should be
>the frontend to allocate and grant the pages, and the backend to
>map them. See the various existing frontend/backend pairs in the
>Linux tree.
>

That's a very important point. Thanks. Can you describe what kind 
of security implications happen if we do the buffer allocation on
the backend and grant the access to front end ?

The buffer that I am talking about contains data that is received
from DOM1 application.

>Jan


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