linux-kernel - Re: [RFC PATCH 0/1] KEYS, integrity: Link .platform keyring to .secondary_trusted

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Date:   Tue, 08 Jan 2019 09:31:49 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Kairui Song <kasong@...hat.com>, linux-kernel@...r.kernel.org
Cc:     dhowells@...hat.com, dwmw2@...radead.org,
        jwboyer@...oraproject.org, keyrings@...r.kernel.org,
        jmorris@...ei.org, serge@...lyn.com, bauerman@...ux.ibm.com,
        ebiggers@...gle.com, nayna@...ux.ibm.com, dyoung@...hat.com
Subject: Re: [RFC PATCH 0/1] KEYS, integrity: Link .platform keyring to
 .secondary_trusted_keys

On Tue, 2019-01-08 at 16:12 +0800, Kairui Song wrote:
> Hi, as the subject, this is a patch that links the new introduced
> .platform keyring into .secondary_trusted_keys keyring. This is
> mainly for the kexec_file_load, make kexec_file_load be able to verify
> the kernel image agains keys provided by platform or firmware.
> kexec_file_load already could verify the image agains secondary_trusted_keys
> if secondary_trusted_keys exits, so this will make kexec_file_load be ware
> of platform keys as well.

The builtin and secondary keyrings have a signature change of trust
rooted in the signed kernel image.  Adding the pre-boot keys to the
secondary keyring breaks that signature chain of trust.

Mimi

> 
> This may also useful for things like module sign verify that are using
> secondary_trusted_keys. I'm not sure if it will be better to move the
> INTEGRITY_PLATFORM_KEYRING to certs/ and let integrity subsystem use
> the keyring there, so just linked the .platform keyring into kernel's
> .secondary_trusted_keys keyring.
> 
> It workd for my case, tested in a VM, I signed the kernel image locally
> with pesign and imported the cert to EFI's MokList variable.
> 
> Kairui Song (1):
>   KEYS, integrity: Link .platform keyring to .secondary_trusted_keys
> 
>  certs/system_keyring.c          | 30 ++++++++++++++++++++++++++++++
>  include/keys/platform_keyring.h | 12 ++++++++++++
>  security/integrity/digsig.c     |  7 +++++++
>  3 files changed, 49 insertions(+)
>  create mode 100644 include/keys/platform_keyring.h
>