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From: Steven Rostedt <>
To: Eric Blake <>
Cc: Stefan Hajnoczi <>,, Stefan Hajnoczi <>,,,,,
	Luiz Capitulino <>,,
Subject: Re: [Qemu-devel] [RFC] host and guest kernel trace merging
Date: Mon, 7 Mar 2016 11:26:27 -0500	[thread overview]
Message-ID: <20160307112627.3b94c671@gandalf.local.home> (raw)
In-Reply-To: <>

On Mon, 7 Mar 2016 09:10:10 -0700
Eric Blake <> wrote:

> On 03/07/2016 08:49 AM, Steven Rostedt wrote:
> > On Mon, 7 Mar 2016 15:17:05 +0000
> > Stefan Hajnoczi <> wrote:
> > 
> >   
> >> qemu-guest-agent runs inside the guest and replies to RPC commands from
> >> the host.  It is used for backups, shutdown, network configuration, etc.
> >> From time to time people have wanted the ability to execute an arbitrary
> >> command inside the guest and return the output.  This functionality has
> >> never been merged, probably for the security reason.  
> > 
> > How's the connection set up. That is, how does it know the commands are
> > coming from the host? And how does it know that the commands from the
> > host is from a trusted source? If the host is compromised, is there
> > anything keeping an intruder from controlling the guest?  
> qemu-guest-agent uses a virtio channel, so only the host can be driving
> that channel.  But how can a guest know that it trusts the host? It
> can't.  A compromised host implicitly compromises all guests, and that's
> always been the case.  At least qemu-guest-agent doesn't make the window
> any larger.

I should have been a bit more clear about what I meant by "host is
compromised". I should have asked, what about untrusted tasks on the
host. Is the channel protected where only admin users can access it?

Of course, one of my concerns with the trace-cmd server is that it may
require a network connection, because doesn't a virtio channel require
to be initialized at boot up? Where the host must have an active
listener when the guest starts? Or am I thinking about something else.

-- Steve

      parent reply	other threads:[~2016-03-07 16:26 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
     [not found] ` <20160304111933.GB626@stefanha-x1.localdomain>
2016-03-04 13:23   ` [Qemu-devel] [RFC] host and guest kernel trace merging Steven Rostedt
     [not found]     ` <20160307151705.GD20937@stefanha-x1.localdomain>
2016-03-07 15:49       ` Steven Rostedt
     [not found]         ` <>
2016-03-07 16:26           ` Steven Rostedt [this message]

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