On Tue, Nov 14, 2017 at 2:31 PM, James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 2017-11-14 at 14:17 -0800, Matthew Garrett wrote: >> Measured boot has a great deal of value in the sealing of private >> material, even in the absence of attestation. The way Microsoft make >> use of PCR7 is a good example of how signatures make this easier - >> achieving the same goal with a full measurement of the boot chain >> instead of relying on signature validation results in significantly >> more fragility. > > OK, so I agree that if you have sealed something required for boot (and > have the capability for resealing it on OS upgrade) you can use > measurements locally. However, I don't believe we have any systems > today in Linux which can do this (we have theoretical ideas about how > we might do it with LUKS root keys and one day we might actually have > the infrastructure to make it viable for a standard laptop). It's used for TPMTOTP, for instance. > Absent that, secure boot provides a reasonable measure of security > which works with today's infrastructure. > > Note: this doesn't mean I necessarily want signatures everywhere (like > firmware). We can sign elements in blobs that provide the effective > security without needing more granular signatures. To be clear - I'm arguing in favour of signatures here. Measured boot is much easier to work with in their presence. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
