Re: [PATCH net] vsock: forward all packets to the host when no H2G is registered

[Alexander Graf]

On 19.11.20 15:03, Stefan Hajnoczi wrote:
> On Thu, Nov 12, 2020 at 02:38:37PM +0100, Stefano Garzarella wrote:
> > Before commit c0cfa2d8a788 ("vsock: add multi-transports support"),
> > if a G2H transport was loaded (e.g. virtio transport), every packets
> > was forwarded to the host, regardless of the destination CID.
> > The H2G transports implemented until then (vhost-vsock, VMCI) always
> > responded with an error, if the destination CID was not
> > VMADDR_CID_HOST.
> >
> >  From that commit, we are using the remote CID to decide which
> > transport to use, so packets with remote CID > VMADDR_CID_HOST(2)
> > are sent only through H2G transport. If no H2G is available, packets
> > are discarded directly in the guest.
> >
> > Some use cases (e.g. Nitro Enclaves [1]) rely on the old behaviour
> > to implement sibling VMs communication, so we restore the old
> > behavior when no H2G is registered.
> > It will be up to the host to discard packets if the destination is
> > not the right one. As it was already implemented before adding
> > multi-transport support.
> >
> > Tested with nested QEMU/KVM by me and Nitro Enclaves by Andra.
> >
> > [1] Documentation/virt/ne_overview.rst
> >
> > Cc: Jorgen Hansen <jhansen@xxxxxxxxxx>
> > Cc: Dexuan Cui <decui@xxxxxxxxxxxxx>
> > Fixes: c0cfa2d8a788 ("vsock: add multi-transports support")
> > Reported-by: Andra Paraschiv <andraprs@xxxxxxxxxx>
> > Tested-by: Andra Paraschiv <andraprs@xxxxxxxxxx>
> > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> > ---
> >   net/vmw_vsock/af_vsock.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> Acked-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>


Is there anything we have to do to also get this into the affected 
stable trees? :)

Alex





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