On Tue, 2021-09-14 at 17:14 -0400, Eric Snowberg wrote: > Back in 2013 Linus requested a feature to allow end-users to have the > ability "to add their own keys and sign modules they trust". This was > his *second* order outlined here [1]. There have been many attempts > over the years to solve this problem, all have been rejected. Many > of the failed attempts loaded all preboot firmware keys into the kernel, > including the Secure Boot keys. Many distributions carry one of these > rejected attempts [2], [3], [4]. This series tries to solve this problem > with a solution that takes into account all the problems brought up in > the previous attempts. > > On UEFI based systems, this series introduces a new Linux kernel keyring > containing the Machine Owner Keys (MOK) called machine. It also defines > a new MOK variable in shim. This variable allows the end-user to decide > if they want to load MOK keys into the machine keyring. Mimi has suggested > that only CA keys contained within the MOK be loaded into the machine > keyring. All other certs will load into the platform keyring instead. > > By default, nothing changes; MOK keys are not loaded into the machine > keyring. They are only loaded after the end-user makes the decision > themselves. The end-user would set this through mokutil using a new > --trust-mok option [5]. This would work similar to how the kernel uses > MOK variables to enable/disable signature validation as well as use/ignore > the db. Any kernel operation that uses either the builtin or secondary > trusted keys as a trust source shall also reference the new machine > keyring as a trust source. > > Secure Boot keys will never be loaded into the machine keyring. They > will always be loaded into the platform keyring. If an end-user wanted > to load one, they would need to enroll it into the MOK. > > Steps required by the end user: > > Sign kernel module with user created key: > $ /usr/src/kernels/$(uname -r)/scripts/sign-file sha512 \ > machine_signing_key.priv machine_signing_key.x509 my_module.ko > > Import the key into the MOK > $ mokutil --import machine_signing_key.x509 > > Setup the kernel to load MOK keys into the .machine keyring > $ mokutil --trust-mok > > Then reboot, the MokManager will load and ask if you want to trust the > MOK key and enroll the MOK into the MOKList. Afterwards the signed kernel > module will load. > > I have included links to both the mokutil [5] and shim [6] changes I > have made to support this new functionality. How hard it is to self-compile shim and boot it with QEMU (I do not know even the GIT location of Shim)? I'm all my SGX testing already with TianoCore and QEMU so I thought it might not be that huge stretch to get testing env for this. /Jarkko
