Hi Paul Thank you for sharing your work. I will look at this patch and check how it works, idea of measuring kernel signature instead of whole binary is very interesting. I hope that next week I will find some time for that, as you said patch is quite big.
Do you plan to add ability to verify public key using VLP? If I understand correctly your current goal is to verify kernel binary with signature and extend PCRs with signature's public key hash, am I right? In this approach tboot is not able to verify if kernel is signed by proper authority, this need to be done be local/remote attestation in further boot process. Thanks, Lukasz On Thu, 2019-09-19 at 15:39 +0000, Paul Moore (pmoore2) via tboot-devel wrote: > Hello, > > I've been working on adding PECOFF/kernel signature verification to > tboot and now that I have a rough working prototype I wanted to bring > it to the list to see if this is something the tboot community would > be interested in eventually merging (once the work is more complete > and polished). > > The patchset is quite large, mostly due to the inclusion of > libtomcrypt and libtomfastmath to the tboot repository, so I'm going > to refrain from spamming the list with the full patchset at this early > stage. The current patchset can be found on GitHub at the URL below > (look in the "working-txtsig" branch): > > * > https://github.com/pcmoore/misc-tboot/tree/working-txtsig > > > The prototype doesn't actually enforce any policy or change the PCR > measurements based on the kernel signatures (both are planned work > items), but it does demonstrate the ability to parse and verify a > signed PECOFF image. The individual patch descriptions provide some > additional information on some of the planned work to take this from > a prototype to a proper implementation. > > My motivation for this work is to create a mechanism that is capable > of generating a stable set of PCR values across multiple kernels that > can be used to seal TPM NVRAM secrets on both legacy BIOS and UEFI > systems. Imagine being able to store a storage encryption key in the > TPM, and restricting access to that key to only authorized kernels in > such a way that didn't require changing the tboot policy when booting > different kernels. I imagine I'm not along in thinking this would > be a nice capability to have, especially on systems that don't support > UEFI Secure Boot. > > For those who are interested, I gave a presentation on this work at > the Linux Security Summit last month, the video and sldies are > available at the links below: > > * > https://www.youtube.com/watch?v=Qbjz_5jUE9o > > * > https://www.paul-moore.com/docs/lss-securing_tpm_with_txt-pmoore-201909-r2.pdf > > > Thoughts? Is this capability something the TXT/tboot community would > be interested in merging into the main tboot repository once it is > more complete? > > _______________________________________________ > tboot-devel mailing list > tboot-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/tboot-devel > > _______________________________________________ tboot-devel mailing list tboot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tboot-devel
