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

[Jason Wang <jasowang@redhat.com>]

Hi:

å 2023/2/22 14:46, Heng Qi åé:
> 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.


Anything may the tunnel different? I think this can happen even without 
tunnel (and even with single queue).

How to mitigate those attackers seems more like a implementation details 
where might require fair queuing or other QOS technology which has been 
well studied.

It seems out of the scope of the spec (unless we want to let driver 
manageable QOS).

Thanks


> Thanks.
>
> > > > +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?