On 2022/11/09 9:25 AM, Eric Snowberg wrote: > >> On Nov 8, 2022, at 6:24 PM, Elaine Palmer <erpalmerny@xxxxxxxxx> wrote: >> >> >> >> On 2022/11/04 9:20 AM, Coiby Xu wrote: >>> Hi Eric, >>> >>> I wonder if there is any update on this work? I would be glad to do >>> anything that may be helpful including testing a new version of code. >>> >> Hi Coiby, >> >> Yes, this discussion got stuck when we couldn't agree on one of the >> following options: >> >> (A) Filter which keys from MOK (or a management system) are loaded >> onto the .machine keyring. Specifically, load only keys with >> CA+keyCertSign attributes. >> >> (B) Load all keys from MOK (or a management system) onto the >> .machine keyring. Then, subsequently filter those to restrict >> which ones can be loaded onto the .ima keyring specifically. >> >> The objection to (A) was that distros would have to go through >> two steps instead of one to load keys. The one-step method of >> loading keys was supported by an out-of-tree patch and then by >> the addition of the .machine keyring. >> >> The objection to (B) was that, because the .machine keyring is now >> linked to the .secondary keyring, it expands the scope of what the >> kernel has trusted in the past. The effect is that keys in MOK >> have the same broad scope as keys previously restricted to >> .builtin and .secondary. It doesn't affect just IMA, but the rest >> of the kernel as well. >> >> I would suggest that we can get unstuck by considering: >> >> (C) Defining a systemd (or dracut module) to load keys onto the >> .secondary keyring >> >> (D) Using a configuration option to specify what types of >> .machine keys should be allowed to pass through to the >> .secondary keyring. >> >> The distro could choose (A) by allowing only >> CA+keyCertSign keys. >> >> The distro could choose (B) by allowing any kind >> of key. >> >> We all seemed to agree that enforcing key usage should be >> implemented and that a useful future effort is to add policies >> to keys and keyrings, like, "This key can only be used for >> verifying kernel modules." >> >> I hope we can come to an agreement so work can proceed and IMA >> can be re-enabled. > I would be open to making the changes necessary to support both (A and B) > options. What type of configuration option would be considered? Would this > be a compile time Kconfig, a Linux boot command line parameter, or another > MOK variable? > Thank you, Eric. A compile time Kconfig would be the most secure, yet would still support (B) when allowed.
