On Thu, Mar 26, 2020 at 1:50 PM Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx> wrote: > It is not part of the EFI entry point as we are not entering the kernel > from EFI but I will address that further in my response to Andy. The > expectation is that if you are on an UEFI platform then EBS should have > already been called. Ok. In that case should the EFI boot stub optionally be calling this instead of startup_32? > With respect to using the firmware's TPM code, one > of the purposes of a TCG Dynamic Launch is to remove the firmware from > the code being trusted in making the integrity measurement of the > kernel. I trust the firmware to initialize the hardware because I have > to and it does give a trust chain, aka the SRTM, that can attest to what > was used during that process. When the OS kernel is being started that > trust chain has become weak (or even broken). I want a new trust chain > that can provide better footing for asserting the integrity of the > kernel and this is what Dynamic Launch gives us. I would like to think I > did a fair job explaining this at LSS last fall[1][2] and would > recommend those that are curious to review the slides/watch the > presentation. PCs depend on the availability of EFI runtime services - it's not possible to just assert that they're untrusted and so unsupported. The TPM code is part of boot services which (based on your design) are unavailable at this point, so I agree that you need your own implementation.
