Re: [PATCH v9 0/4] unify the keyrings of arm64 and s390 with x86 to verify kexec'ed kernel signature

On Wed, 2022-07-06 at 12:48 +0100, Will Deacon wrote:

On Wed, Jul 06, 2022 at 07:35:36AM -0400, Mimi Zohar wrote:

quoted

On Mon, 2022-07-04 at 09:51 +0800, Coiby Xu wrote:

quoted

Currently when loading a kernel image via the kexec_file_load() system
call, x86 can make use of three keyrings i.e. the .builtin_trusted_keys,
.secondary_trusted_keys and .platform keyrings to verify a signature.
However, arm64 and s390 can only use the .builtin_trusted_keys and
.platform keyring respectively. For example, one resulting problem is
kexec'ing a kernel image  would be rejected with the error "Lockdown:
kexec: kexec of unsigned images is restricted; see man
kernel_lockdown.7".

This patch set enables arm64 and s390 to make use of the same keyrings
as x86 to verify the signature kexec'ed kernel image.

[...]

quoted

quoted

For arm64, the tests were done as follows,
  1. build 5.19.0-rc2
  2. generate keys and add them to .secondary_trusted_keys, MOK, UEFI
     db;
  3. sign different kernel images with different keys including keys
     from .builtin_trusted_key, .secondary_trusted_keys keyring, a UEFI db
     key and MOK key
  4. Without lockdown, all kernel images can be kexec'ed; with lockdown
     enabled, only the kernel image signed by the key from the
     .builtin_trusted_key keyring can be kexec'ed

Just confirming, for arm64, this patch set allows verifying the
kexec'ed kernel image signature using keys on either the .platform or
.secondary_trusted_keys keyrings.

It looks like this series is ready to go, but it's not clear who should
pick it up. Eric -- would you be the best person? Otherwise, I'm happy to
take it via the arm64 tree (on its own branch) if that would be helpful.

Unless Eric is interested, I was asked to pick this patch set up.

thanks,

Mimi


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