Re: [PATCH v2 0/3] xen: harden blkfront against malicious backends

From: Konrad Rzeszutek Wilk
Date: Thu Jul 08 2021 - 10:22:49 EST

On Thu, Jul 08, 2021 at 02:43:42PM +0200, Juergen Gross wrote:
> Xen backends of para-virtualized devices can live in dom0 kernel, dom0
> user land, or in a driver domain. This means that a backend might
> reside in a less trusted environment than the Xen core components, so
> a backend should not be able to do harm to a Xen guest (it can still
> mess up I/O data, but it shouldn't be able to e.g. crash a guest by
> other means or cause a privilege escalation in the guest).
> Unfortunately blkfront in the Linux kernel is fully trusting its
> backend. This series is fixing blkfront in this regard.
> It was discussed to handle this as a security problem, but the topic
> was discussed in public before, so it isn't a real secret.

Wow. This looks like what Marek did .. in 2018!

Would it be worth crediting Marek?
> Changes in V2:
> - put blkfront patches into own series
> - some minor comments addressed
> Juergen Gross (3):
> xen/blkfront: read response from backend only once
> xen/blkfront: don't take local copy of a request from the ring page
> xen/blkfront: don't trust the backend response data blindly
> drivers/block/xen-blkfront.c | 122 +++++++++++++++++++++++------------
> 1 file changed, 80 insertions(+), 42 deletions(-)
> --
> 2.26.2