Messages in this thread | | | Date | Fri, 18 Jan 2019 16:33:48 +0200 | From | Jarkko Sakkinen <> | Subject | Re: [PATCH 1/5 v2] PM / hibernate: Create snapshot keys handler |
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On Fri, Jan 11, 2019 at 07:28:58AM -0800, James Bottomley wrote: > On Fri, 2019-01-11 at 16:02 +0200, Jarkko Sakkinen wrote: > > On Tue, Jan 08, 2019 at 05:43:53PM -0800, Andy Lutomirski wrote: > > > (Also, do we have a sensible story of how the TPM interacts with > > > hibernation at all? Presumably we should at least try to replay > > > the PCR operations that have occurred so that we can massage the > > > PCRs into the same state post-hibernation. Also, do we have any > > > way for the kernel to sign something with the TPM along with an > > > attestation that the signature was requested *by the > > > kernel*? Something like a sub-hierarchy of keys that the kernel > > > explicitly prevents userspace from accessing?) > > > > Kernel can keep it is own key hierarchy in memory as TPM2 chips allow > > to offload data in encrypted form and load it to TPM when it needs to > > use it. > > > > The in-kernel resource manager that I initiated couple years ago > > provides this type of functionality. > > Actually, the resource manager only keeps volatile objects separated > when in use not when offloaded. The problem here is that the object > needs to be persisted across reboots, so either it gets written to the > NV area, bypassing the resource manager and making it globally visible > or it has to get stored in TPM form in the hibernation image, meaning > anyone with access to the TPM who can read the image can extract and > load it. Further: anyone with access to the TPM can create a bogus > sealed key and encrypt a malicious hibernation image with it. So there > are two additional problems > > 1. Given that the attacker may have access to the binary form of the > key, can we make sure only the kernel can get it released? > 2. How do we prevent an attacker with access to the TPM from creating a > bogus sealed key? > > This is why I was thinking localities.
Why you would want to go for localities and not seal to PCRs?
/Jarkko
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