Messages in this thread | | | From | Krzysztof Struczynski <> | Subject | RE: [RFC PATCH 00/30] ima: Introduce IMA namespace | Date | Fri, 21 Aug 2020 15:13:01 +0000 |
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> From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com] > On Tue, 2020-08-18 at 17:20 +0200, krzysztof.struczynski@huawei.com > wrote: > > The measurement list remains global, with the assumption that there > > is only one TPM in the system. Each IMA namespace has a unique ID, > > that allows to track measurements per IMA namespace. Processes in one > > namespace, have access only to the measurements from that namespace. > > The exception is made for the initial IMA namespace, whose processes > > have access to all entries. > > So I think this can work in the use case where the system owner is > responsible for doing the logging and attestation and the tenants just > trust the owner without requiring an attestation. However, in a multi- > tenant system you need a way for the attestation to be per-container > (because the combined list of who executed what would be a security > leak between tenants). Since we can't virtualise the PCRs without > introducing a vtpm this is going to require a vtpm infrastructure like > that used for virtual machines and then we can do IMA logging per > container.
I agree and wonder if we should decouple the attestation trust model, which depends on the specific use case (e.g. multi/single tenant, public/private cloud), from the IMA logic of linking the measurements to the container. Indeed, attestation from within the container might require anchoring to a vTPM/vPCR and the current measurement tagging mechanism can support several ways of anchoring them to a (virtual) root of trust.
> I don't think the above has to be in your first patch set, we just have > to have an idea of how it could be done to show that nothing in this > patch set precludes a follow on from doing this.
Given that virtualizing trust anchors seems like a separate problem in which industry consensus is not easy to reach for all use cases, an anchoring mechanism should probably be a separate IMA feature.
> > James
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