On Sun, 2018-03-11 at 11:20 +0800, joeyli wrote:

On Wed, Mar 07, 2018 at 07:28:37AM -0800, James Bottomley wrote:

quoted

On Wed, 2018-03-07 at 08:18 -0500, Mimi Zohar wrote:

quoted

On Tue, 2018-03-06 at 15:05 +0100, Jiri Slaby wrote:

quoted

what's the status of this please? Distributors (I checked SUSE,
RedHat and Ubuntu) have to carry these patches and every of them
have to forward-port the patches to new kernels. So are you going
to resend the PR to have this merged?

[...]

quoted

Just because I trust the platform keys prior to booting the kernel,
doesn't mean that I *want* to trust those keys once booted. ?There
are, however, places where we need access to those keys to verify a
signature (eg. kexec kernel image).

Which is essentially the reason I always give when these patches come
back

Josh Boyer's "MODSIGN: Allow the "db" UEFI variable to be suppressed"
patch checks MokIgnoreDB variable to ignore db:

https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit/?h=keys-uefi&id=7c395b30a33a617c5cc2cdd419300af71277b79a

I think that we can consider to use MokAllowDB. Which means that kernel
ignores DB by default.

Not all systems have a shim layer.??This design is really x86
specific.??Allowing shim keys, but ignoring DB, does not address those
systems.

quoted

quoted

Nayna Jain's "certs: define a trusted platform keyring" patch set
introduces a new, separate keyring for these platform keys.

Perhaps, to break the deadlock, we should ask Ji?? what the reason is
the distros want these keys to be trusted. ?Apart from the Microsoft
key, it will also give you an OEM key in your trusted keyring. ?Is it
something to do with OEM supplied modules?

As I remember that some manufacturers uses certificate in db to
sign their kernel module. We need to discuss with them for switching
to mok. Currently I do not know all use cases for using db.

There have some benefits for using db:

 - User does not need to deal with shim-mokmanager to enroll mok.
   Target machine doesn't need to reboot and user doesn't need to
   face to mokmanager UI.  

The reason for trusting enrolled shim keys is because it requires
physical presence. ?(I kind of remember hearing that this changed.
?There is some method of accepting enrolled keys that does not require
physical presence.)

 - The db is a authenticated variable, it's still secure when secure
   boot is disabled.
   The db is a authenticated variable that it can only be modified
   by manufacturer's key. Kernel can trust it when secure boot
   is disabled. It's useful for we do not need to taint kernel
   for loading a manufacturer's kernel module even secure boot is
   disabled.

 - Do not need to worry about the space of NVRAM and the EFI firmware
   implementation for writing a boot time variable.
  
But I also agree that we should not trust all keys (like Microsoft key)
in db by default.

Between requiring a shim layer and relying on physical presence, I'm
not convinced this is the best solution. ?Do we really want to support
different methods for different architectures?

Mimi

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