Re: [PATCH] vhost/vsock: accept only packets with the right dst_cid

Stefano Garzarella
2019-12-10T14:32:59Z

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@redhat.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