On Thu, 2021-09-16 at 18:14 -0400, Peter Jones wrote:

On Thu, Sep 16, 2021 at 06:15:50PM +0300, Jarkko Sakkinen wrote:

quoted

On Wed, 2021-09-15 at 15:28 -0600, Eric Snowberg wrote:

quoted

quoted

On Sep 15, 2021, at 11:57 AM, Jarkko Sakkinen [off-list ref] wrote:

On Tue, 2021-09-14 at 17:14 -0400, Eric Snowberg wrote:

quoted

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)?

It is not hard, that is the setup I use for my testing.  Upstream shim 
is located here [1].  Or you can use my repo which contains the necessary
changes [2].

[1] https://github.com/rhboot/shim
[2] https://github.com/esnowberg/shim/tree/mokvars-v2

So, my 2nd Q would be: which order these should be upstreamed?

Linux patch set cannot depend on "yet to be upstreamed" things.

Code changes look good enough to me.

We can carry this support in shim before it's in kernel.  Eric's current
patch for shim and mokutil looks mostly reasonable, though I see a few
minor nits we'll have to sort out.

I would revisit this patch set after there is an official shim release
out containing the new API. No  kernel patches, which depend on any
non-upstream changes, can be rightfully reviewed.

/Jarkko