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Re: [Xen-devel] xenconsoled CPU denial of service problem

To: "Daniel P. Berrange" <berrange@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] xenconsoled CPU denial of service problem
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 28 Aug 2006 21:57:22 +0100
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On 28/8/06 7:02 pm, "Daniel P. Berrange" <berrange@xxxxxxxxxx> wrote:

> Does anyone know of any alternative approach to detecting whether the fd
> for the master end of a psuedo-TTY, has a its end slave open / active ?
> Without being able to detect this I don't see any good way to avoid the DOS
> attack in the general case - only other option would be to start dropping
> data once > a certain rate, but this isn't really very desirable because
> there are (debug) scenarios in which you really do want the ability to
> capture all data.

The protocol has flow control. If we rate-limited xenconsoled consumption of
data from each domU ring, we would limit resource consumption in dom0 and
not lose any data (since the domU will simply buffer it internally).

 -- Keir

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