Re: [PATCH v9] virtio-net: support inner header hash

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Feb 22, 2023 at 02:46:51PM +0800, Heng Qi wrote:
> Hi, Jason. Long time no see. :)
> 
> å 2023/2/22 äå11:22, Jason Wang åé:
> > 
> > å 2023/2/22 01:50, Michael S. Tsirkin åé:
> > > On Sat, Feb 18, 2023 at 10:37:15PM +0800, Heng Qi wrote:
> > > > +\subparagraph{Security risks between encapsulated packets and RSS}
> > > > +There may be potential security risks when encapsulated packets
> > > > using RSS to
> > > > +select queues for placement. When a user inside a tunnel tries
> > > > to control the
> > 
> > 
> > What do you mean by "user" here? Is it a remote or local one?
> > 
> 
> I mean a remote attacker who is not under the control of the tunnel owner.
> 
> Thanks.

OK let's just say "remote attacker" then.

> > 
> > > > +enqueuing of encapsulated packets, then the user can flood the
> > > > device with invaild
> > > > +packets, and the flooded packets may be hashed into the same
> > > > queue as packets in
> > > > +other normal tunnels, which causing the queue to overflow.
> > > > +
> > > > +This can pose several security risks:
> > > > +\begin{itemize}
> > > > +\item Encapsulated packets in the normal tunnels cannot be
> > > > enqueued due to queue
> > > > +ÂÂÂÂÂÂ overflow, resulting in a large amount of packet loss.
> > > > +\item The delay and retransmission of packets in the normal
> > > > tunnels are extremely increased.
> > > > +\item The user can observe the traffic information and enqueue
> > > > information of other normal
> > > > +ÂÂÂÂÂÂ tunnels, and conduct targeted DoS attacks.
> > > > +\end{\itemize}
> > > > +
> > > Hmm with this all written out it sounds pretty severe.
> > 
> > 
> > I think we need first understand whether or not it's a problem that we
> > need to solve at spec level:
> > 
> > 1) anything make encapsulated packets different or why we can't hit this
> > problem without encapsulation
> > 
> > 2) whether or not it's the implementation details that the spec doesn't
> > need to care (or how it is solved in real NIC)
> > 
> > Thanks
> > 
> > 
> > > At this point with no ways to mitigate, I don't feel this is something
> > > e.g. Linux can enable. I am not going to nack the spec patch if
> > > others find this somehow useful e.g. for dpdk.
> > > How about CC e.g. dpdk devs or whoever else is going to use this
> > > and asking them for the opinion?
> > > 
> > >