Re: [Xen-devel] Q: How to find own domid or uuid from domU?

[Ewan Mellor <ewan@xxxxxxxxxxxxx>]

On Tue, May 23, 2006 at 09:31:21AM +0100, Christian Limpach wrote:

> On Tue, May 23, 2006 at 09:52:00AM +0200, Markus Armbruster wrote:
> > "Christian Limpach" <christian.limpach@xxxxxxxxx> writes:
> > 
> > > There's a uuid node under the vm path.  I.e. you'd do:
> > > vmpath=$(xenstore-read vm)
> > > uuid=$(xenstore-read $vmpath/uuid)
> > 
> > Fails in domU:
> > 
> >     # xenstore-read vm
> >     /vm/947df77a-58b5-4e3d-9b6c-aa0178d8e133
> >     # xenstore-read /vm/947df77a-58b5-4e3d-9b6c-aa0178d8e133/uuid
> >     xenstore-read: couldn't read path 
> > /vm/947df77a-58b5-4e3d-9b6c-aa0178d8e133/uuid
> 
> Indeed, it's either broken because we've set the permissions not to
> allow domains to have access to the /vm tree or because we don't allow
> domains to read outside of their "home" directory.

Permissions for doing this are set in Xend.  At the moment, for security, we
only allow a domain to look at /local/domain/<domid>, and
/local/domain/0/backend/<device type>/<domid>, IIRC.  If it is reasonable to
allow a guest to determine its UUID, then we could trivially add that to Xend,
by allowing it to read that particular value from the vm directory.

Ewan.

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