linux-kernel - Re: [PATCH 0/7] add platform/firmware keys support for kernel verification by IMA

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Date:   Wed, 28 Nov 2018 11:45:27 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Nayna Jain <nayna@...ux.ibm.com>, linux-integrity@...r.kernel.org
Cc:     linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org,
        linux-kernel@...r.kernel.org, dhowells@...hat.com,
        jforbes@...hat.com, seth.forshee@...onical.com,
        kexec@...ts.infradead.org, keyrings@...r.kernel.org,
        vgoyal@...hat.com, ebiederm@...ssion.com, mpe@...erman.id.au
Subject: Re: [PATCH 0/7] add platform/firmware keys support for kernel
 verification by IMA

Hi Nayna,

On Sun, 2018-11-25 at 20:44 +0530, Nayna Jain wrote:
> On secure boot enabled systems, a verified kernel may need to kexec
> additional kernels. For example, it may be used as a bootloader needing
> to kexec a target kernel or it may need to kexec a crashdump kernel.
> In such cases, it may want to verify the signature of the next kernel
> image.
> 
> It is possible that the new kernel image is signed with third party keys
> which are stored as platform or firmware keys in the 'db' variable. The
> kernel, however, can not directly verify these platform keys, and an
> administrator may therefore not want to trust them for arbitrary usage.
> In order to differentiate platform keys from other keys and provide the
> necessary separation of trust the kernel needs an additional keyring to
> store platform/firmware keys.
> 
> The secure boot key database is expected to store the keys as EFI
> Signature List(ESL). The patch set uses David Howells and Josh Boyer's
> patch to access and parse the ESL to extract the certificates and load
> them onto the platform keyring.
> 
> The last patch in this patch set adds support for IMA-appraisal to
> verify the kexec'ed kernel image based on keys stored in the platform
> keyring.
> 
> Changelog:
> 
> v0:
> - The original patches loaded the certificates onto the secondary
>   trusted keyring. This patch set defines a new keyring named
>   ".platform" and adds the certificates to this new keyring  
> - removed CONFIG EFI_SIGNATURE_LIST_PARSER and LOAD_UEFI_KEYS
> - moved files from certs/ to security/integrity/platform_certs/

This patch set is looking really good!  There are a couple of
checkpatch.pl warnings that need to be addressed before these patches
can be upstreamed.  I'd also like to see some Reviews/Acks for them as
well.

For the time being these patches are queued in the #next-integrity-
queued branch.

https://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.
git/

thanks!

Mimi

> 
> Dave Howells (2):
>   efi: Add EFI signature data types
>   efi: Add an EFI signature blob parser
> 
> Josh Boyer (2):
>   efi: Import certificates from UEFI Secure Boot
>   efi: Allow the "db" UEFI variable to be suppressed
> 
> Nayna Jain (3):
>   integrity: define a trusted platform keyring
>   integrity: load certs to the platform keyring
>   ima: support platform keyring for kernel appraisal
> 
>  include/linux/efi.h                                |  34 ++++
>  security/integrity/Kconfig                         |  11 ++
>  security/integrity/Makefile                        |   5 +
>  security/integrity/digsig.c                        | 115 ++++++++----
>  security/integrity/ima/ima_appraise.c              |  11 +-
>  security/integrity/integrity.h                     |  23 ++-
>  security/integrity/platform_certs/efi_parser.c     | 112 ++++++++++++
>  security/integrity/platform_certs/load_uefi.c      | 192 +++++++++++++++++++++
>  .../integrity/platform_certs/platform_keyring.c    |  62 +++++++
>  9 files changed, 527 insertions(+), 38 deletions(-)
>  create mode 100644 security/integrity/platform_certs/efi_parser.c
>  create mode 100644 security/integrity/platform_certs/load_uefi.c
>  create mode 100644 security/integrity/platform_certs/platform_keyring.c
>