Re: [Xen-users] Should applications be running on Dom0

[Jonathan Tripathy <jonnyt@xxxxxxxxxxx>]

Much more simple: Dom0 has access to all disks of all DomUs - no 
exploits required :)


On 17/08/10 21:20, Joseph M. Deming wrote:
>  From a casual xen user's point of view (ie i'm not a certified
> professional or dev).
>
> Xen dom0 (using my setup in debian as an example) is really just another
> domU loaded under the Xen hypervisor itself.  It is 'privileged' in a
> sense of controlling the other DomU's and the hardware/virtual device
> connections between them, but it is also really just another running
> kernel/installation of a Debian OS in my case.
>
> So... apt-get installing packages, running services, etc, etc is really
> independent of the responsibilities of the Xen virtualization.  So,
> there should be no reason other apps can't run alongside the Xen
> application in the Dom0.
>
> However, I assume the general recommendation that apps should NOT be run
> alongside Xen in the main Dom0 (especially in production environment)
> would stem from two primary thought-processes (maybe more, but these are
> the 2 I think about).
>
>
> 1)  Applications running on DomO could, theoretically, compromise
> security between the Dom0 boxes and the DomU's by providing further
> handles that could be leveraged if a security loophole is exploited in
> Xen.  In other words, by keeping the DomO as a nice clean, minimal
> install you minimize the vector of attacks possible that would be
> possible by gaining access to the Dom0 kernel or communication between
> Dom0's and DomU devices.
>
> 2)  Applications running on Dom0, I assume, bypass some of the resource
> management that comes on the DomU virtual (and even passthrough)
> devices.  Meaning, if you install an application on Dom0 that is
> io-intensive on any bus (disk, network, memory, CPU) you can drag the
> performance of possibly all your DomU's because the DomO is somewhat in
> control and dominating disk read/write for example.
>
> I am writing this with a lack of fundamental understanding of the exact
> technical design of the Xen system, but I think that the 2 concepts
> listed here apply in a general sense even if my wording or technical
> terms are somewhat incorrect.  Hope maybe this helps shed a little
> light.
>
> - jmd
>
> On Tue, 2010-08-17 at 19:47 +0000, Nathan Eisenberg wrote:
>    
> > I hear this often, but I have yet to hear a satisfactory and technical
> > explanation as to why.  Iâm not sure I agree that it is true.
> >
> >
> >
> > Why is this the case?
> >
> >
> >
> > -Nathan
> >
> >
> >
> > From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> > [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Jonathan
> > Tripathy
> > Sent: Tuesday, August 17, 2010 12:35 PM
> > To: Brent Bolin; Xen-users@xxxxxxxxxxxxxxxxxxx
> > Subject: RE: [Xen-users] Should applications be running on Dom0
> >
> >
> >
> >
> > Depends on what your Xen setup is being used for.
> >
> >
> >
> >
> >
> > If it's strictly lab/testing/internal things, then it really doesn't
> > matter
> >
> >
> >
> >
> >
> > If you're hosting stuff to the outside world, then the only thing that
> > should be running on the Dom0 (apart from the Xen Guests), is iptables
> > to firewall the guests.
> >
> >
> >
> >
> >
> > ______________________________________________________________________
> > From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx on behalf of Brent Bolin
> > Sent: Tue 17/08/2010 20:27
> > To: Xen-users
> > Subject: [Xen-users] Should applications be running on Dom0
> >
> >
> > Or should Dom0 be lightweight with guest o/s's be doing that?
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-users
> >
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-users
> >      
>    
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