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Re: [PATCH] Revert "evtchn: refuse EVTCHNOP_status for Xen-bound event channels"
- To: "Oleksii K." <oleksii.kurochko@xxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Fri, 17 May 2024 09:01:33 +0200
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- Cc: George Dunlap <George.Dunlap@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Daniel Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "committers@xxxxxxxxxxxxxx" <committers@xxxxxxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Delivery-date: Fri, 17 May 2024 07:01:38 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 16.05.2024 21:15, Oleksii K. wrote:
> I am not deeply familiar with the technical details surrounding XSM,
> but if I understand Daniel's point correctly, the original change
> violates the access control framework. This suggests to me that the
> revert should be merged.
>
> However, I have a question: if we merge this revert, does it mean that
> using channels a user ( domain ) will be able to get information about
> certain events such as EVTCHNSTAT_unbound, EVTCHNSTAT_interdomain,
> EVTCHNSTAT_pirq, EVTCHNSTAT_virq, and EVTCHNSTAT_IPI (based on the code
> of lseventch.c)? Is this information really so critical that it cannot
> be exposed for some time until a patch that changes the XSM policy
> consistently is provided and merged?
>
> If this information is indeed critical and should not be exposed, I
> think we can consider Daniel's suggestion to add a check to the dummy
> XSM policy as a solution.
The question isn't whether it's critical. As pointed out elsewhere, my
view is that any exposure of information needs to come with a proof that
nothing undue can be derived from that information. I see Daniel has
responded there, so we'll continue the discussion there.
Jan
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