netdev - Re: [PATCH] vhost/vsock: accept only packets with the right dst

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Message-ID: <20191210143251.szkicty23b6pojxh@steredhat>
Date:   Tue, 10 Dec 2019 15:32:51 +0100
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     virtualization@...ts.linux-foundation.org,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Jason Wang <jasowang@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] vhost/vsock: accept only packets with the right dst_cid

On Tue, Dec 10, 2019 at 09:05:58AM -0500, Michael S. Tsirkin wrote:
> On Fri, Dec 06, 2019 at 03:39:12PM +0100, Stefano Garzarella wrote:
> > When we receive a new packet from the guest, we check if the
> > src_cid is correct, but we forgot to check the dst_cid.
> > 
> > The host should accept only packets where dst_cid is
> > equal to the host CID.
> > 
> > Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
> 
> what's the implication of processing incorrect dst cid?
> I think mostly it's malformed guests, right?

Exaclty, as for the src_cid.

In both cases the packet may be delivered to the wrong socket in the
host, because in the virtio_transport_recv_pkt() we are using the
src_cid and dst_cid to look for the socket where to queue the packet.

> Everyone else just passes the known host cid ...

Yes, good guests should do it, and we do it :-)

Thanks,
Stefano