On Thu, Nov 10, 2022 at 12:54:43AM +0000, Eric Snowberg wrote: > > > > On Nov 9, 2022, at 5:01 PM, Morten Linderud <morten@xxxxxxxxxxx> wrote: > > > > On Tue, Nov 23, 2021 at 11:41:23PM -0500, Eric Snowberg wrote: > >> A new Machine Owner Key (MOK) variable called MokListTrustedRT has been > >> introduced in shim. When this UEFI variable is set, it indicates the > >> end-user has made the decision themselves that they wish to trust MOK keys > >> within the Linux trust boundary. It is not an error if this variable > >> does not exist. If it does not exist, the MOK keys should not be trusted > >> within the kernel. > > > > Hi Eric, > > > > I've been milling around on this patch-set for a while and I have a few issues > > with the description of the commit and what the code actually does. > > > > efi_mokvar_entry_find doesn't simply read an UEFI variable as the commit message > > suggests, it will look for the MOK variable loaded into the EFI configuration > > table. This implies we need this table setup in early boot to take usage of this > > patch set. > > > > The only bootloader that does setup this table, is the `shim` as described. But > > no other bootloader implements support for the MOK EFI configuration table. > > > > This effectively means that there is still no way for Machine Owners to load > > keys into the keyring, for things like module signing, without the shim present > > in the bootchain. I find this a bit weird. > > > > Is this an intentional design decision, or could other ways be supported as > > well? > > In v6 I had it as a RT variable, during the review a request was made [1] to just > use the EFI configuration table. If there are other boot loaders that want to use this, > I don’t see why the code in v6 couldn’t be added back. If the configuration table isn’t > available, it could try reading the RT var next. > > 1. https://patchwork.kernel.org/project/linux-integrity/patch/20210914211416.34096-13-eric.snowberg@xxxxxxxxxx/#24453409 > If we could support both the EFI variables and the EFI configuration table setup it would hopefully be easier for others to implement the interface? I wouldn't mind trying to write a patch for that if others think it's a good idea. I'm not really sure what Peter means with "much more reliable" though. -- Morten Linderud PGP: 9C02FF419FECBE16
