Re: [virtio-dev] Re: [PATCH 0/5] virtio: introduce SUSPEND bit and vq state

Zhu, Lingshan
2023-09-20T11:27:14Z

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On 9/20/2023 7:15 PM, Parav Pandit wrote:
>
> Random words like malicious SW to describe an attack do not make sense.
>
this is not random wording, "malicious" used a lot in the papers,
you can search in google scholar
>
> Refer the patches and series and usage model to describe the sw attack
> if any.
>
> I disagree and I will not repeat all the points anymore.
>
don't only say you disagree, please provide why it is not an attacking
surface.

The problem still exist:

What if a malicious SW dump guest memory through admin vq LM facility?

I think this is end of this discussion.
>
> If you have comments in [1], please reply in [1].
>
> Series [1] clearly describes the usage model at least for one widely
> used OS = Linux.
>
> [1]
> https://lore.kernel.org/virtio-comment/20230909142911.524407-7-parav@nvidia.com/T/#md9fcfa1ba997463de8c7fb8c6d1786b224b0bead
>
> *From:* Zhu, Lingshan <lingshan.zhu@intel.com>
> *Sent:* Wednesday, September 20, 2023 4:41 PM
> *To:* Parav Pandit <parav@nvidia.com>; Michael S. Tsirkin <mst@redhat.com>
> *Cc:* virtio-dev@lists.oasis-open.org; Jason Wang <jasowang@redhat.com>
> *Subject:* Re: [virtio-dev] Re: [PATCH 0/5] virtio: introduce SUSPEND
> bit and vq state
>
> On 9/20/2023 5:52 PM, Parav Pandit wrote:
>
> Hi Lingshan,
>
> Last two email replies in non-next format are getting hard to follow.
>
> Can you please revert back to have text-based emails?
>
> When one wants to use PF for the live migration in trusted
> hypervisor, PF is in the trust zone.
>
> even without live migration, it can be an attacking surface while
> guest running.
> As repeated for many times, it can be used by malicious SW to dump
> guest memory
>
> In future when hypervisor is not trusted, the task of LM will be
> delegated to other infrastructure TVM.
>
> Ravi at Intel already explained this a year ago using migration TD.
>
> This fits very well without bifurcating the member device which is
> extremely hard.
>
> TD, TDX or TDX-IO are more complex topics, and we should
> focus on our live migration solution, not CC.
>
> My point is: using bar cap as a proxy for admin vq based LM is still
> problematic.
>
> Maybe we can close this.
>
> Parav
>
> *From:* Zhu, Lingshan <lingshan.zhu@intel.com>
> <mailto:lingshan.zhu@intel.com>
> *Sent:* Wednesday, September 20, 2023 3:15 PM
> *To:* Parav Pandit <parav@nvidia.com> <mailto:parav@nvidia.com>;
> Michael S. Tsirkin <mst@redhat.com> <mailto:mst@redhat.com>
> *Cc:* virtio-dev@lists.oasis-open.org; Jason Wang
> <jasowang@redhat.com> <mailto:jasowang@redhat.com>
> *Subject:* Re: [virtio-dev] Re: [PATCH 0/5] virtio: introduce
> SUSPEND bit and vq state
>
> On 9/20/2023 4:34 PM, Parav Pandit wrote:
>
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>
> > There can be malicious SW on the host, and the host may be
> hacked and compromised.
> > For example:
> > 1) SUSPEND the a running guest by admin vq
> > 2) dumping guest memory through admin vq dirty page tracking.
>
>
>
> No. hypervisor is trusted entity who is hosting the VM.
>
> The PF may not owned by the hypervisor and the host can be hacked
> and computerized.
>
>
> The device migration is initiated by the hypervisor.
>
> I am omitting the TDISP question for now as talked before.
>
> TDISP spec will evolve for hypercalls when we get there.
>
> Confidential computing is out of the spec, as we discussed and agreed.
>
> This is to demonstrate why even using a bar cap as proxy for admin
> vq LM is still problematic.
> TDISP gives examples of the attacking models, and admin vq based LM
> conforms to the models.
>
>
> *From:*virtio-dev@lists.oasis-open.org
> <virtio-dev@lists.oasis-open.org>
> <mailto:virtio-dev@lists.oasis-open.org> *On Behalf Of *Zhu,
> Lingshan
> *Sent:* Wednesday, September 20, 2023 12:01 PM
> *To:* Parav Pandit <parav@nvidia.com>
> <mailto:parav@nvidia.com>; Michael S. Tsirkin <mst@redhat.com>
> <mailto:mst@redhat.com>
> *Cc:* virtio-dev@lists.oasis-open.org; Jason Wang
> <jasowang@redhat.com> <mailto:jasowang@redhat.com>
> *Subject:* Re: [virtio-dev] Re: [PATCH 0/5] virtio: introduce
> SUSPEND bit and vq state
>
> On 9/20/2023 2:08 PM, Parav Pandit wrote:
>
>
>
> From: Zhu, Lingshan<lingshan.zhu@intel.com> <mailto:lingshan.zhu@intel.com>
>
> Sent: Wednesday, September 20, 2023 11:36 AM
>
>
>
> On 9/19/2023 2:49 AM, Michael S. Tsirkin wrote:
>
> On Mon, Sep 18, 2023 at 06:41:55PM +0000, Parav Pandit wrote:
>
> Please refer to the code for setting FEATURES_OK.
>
> It wont work when one needs to suspend the device.
>
> There is no point of doing such work over registers as fundamental
>
> framework is over the AQ.
>
> Well not really. It's over admin commands. When these were built the
>
> intent always was that it's possible to use admin commands through
>
> another interface, other than admin queue. Is there a problem
>
> implementing admin commands over a memory BAR? For example, I can see
>
> an "admin command" capability pointing at a BAR where commands are
>
> supplied, and using a new group type referring to device itself.
>
> I am not sure, if a bar cap would be implemented as a proxy for the admin vq
>
> based live migration. then the problems of admin vq LM that we have discussed
>
> still exist. the bar is only a proxy, doesn't fix anything. and even larger side
>
> channel attacking surface: vf-->pf-->vf
>
>
>
> AQ LM using PF has no side channel attack as hypervisor and owner device is trusted entity as already discussed.
>
> I believe we have discussed this for many times, and I even
> provide you some examples.
>
> Let me repeat for the last time.
>
> There can be malicious SW on the host, and the host may be
> hacked and compromised.
> For example:
> 1) SUSPEND the a running guest by admin vq
> 2) dumping guest memory through admin vq dirty page tracking.
>
> These above can happen right?
>
> You made TDISP as an example, but have you really read the
> TDISP spec?
> In the spec:
>
> Device Security Architecture - Administrative interfaces
> (e.g., a PF) may be
> used to influence the security properties of the TDI used by
> the TVM.
>
> TEE-I/O requires the device to organize its hardware/software
> interfaces such that the PF cannot
> be used to affect the security of a TDI when it is in use by a TVM
>
> Clear?
>
>
>
>
>

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