linux-kernel - Re: [PATCH v9 0/3] integrity: support including firmware ".platform" keys at build time

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Date:   Sat, 5 Mar 2022 20:32:43 -0500
From:   Nayna <nayna@...ux.vnet.ibm.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Nayna Jain <nayna@...ux.ibm.com>
Cc:     linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        dhowells@...hat.com, zohar@...ux.ibm.com,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, dimitri.ledkov@...onical.com,
        seth@...shee.me, rnsastry@...ux.ibm.com
Subject: Re: [PATCH v9 0/3] integrity: support including firmware ".platform"
 keys at build time


On 3/5/22 00:49, Jarkko Sakkinen wrote:
> On Sat, Mar 05, 2022 at 07:37:18AM +0200, Jarkko Sakkinen wrote:
>> On Fri, Mar 04, 2022 at 12:54:00PM -0500, Nayna Jain wrote:
>>> Some firmware support secure boot by embedding static keys to verify the
>>> Linux kernel during boot. However, these firmware do not expose an
>>> interface for the kernel to load firmware keys onto the ".platform"
>>> keyring, preventing the kernel from verifying the kexec kernel image
>>> signature.
>>>
>>> This patchset exports load_certificate_list() and defines a new function
>>> load_builtin_platform_cert() to load compiled in certificates onto the
>>> ".platform" keyring.
>>>
>>> Changelog:
>>> v9:
>>> * Rebased on tpmdd master branch repo -
>>> git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git
>>>
>>> v8:
>>> * Includes Jarkko's feedback on patch description and removed Reported-by
>>> for Patch 1.
>>>
>>> v7:
>>> * Incldues Jarkko's feedback on patch description for Patch 1 and 3.
>>>
>>> v6:
>>> * Includes Jarkko's feedback:
>>>   * Split Patch 2 into two.
>>>   * Update Patch description.
>>>
>>> v5:
>>> * Renamed load_builtin_platform_cert() to load_platform_certificate_list()
>>> and config INTEGRITY_PLATFORM_BUILTIN_KEYS to INTEGRITY_PLATFORM_KEYS, as
>>> suggested by Mimi Zohar.
>>>
>>> v4:
>>> * Split into two patches as per Mimi Zohar and Dimitri John Ledkov
>>> recommendation.
>>>
>>> v3:
>>> * Included Jarkko's feedback
>>>   ** updated patch description to include approach.
>>>   ** removed extern for function declaration in the .h file.
>>> * Included load_certificate_list() within #ifdef CONFIG_KEYS condition.
>>>
>>> v2:
>>> * Fixed the error reported by kernel test robot
>>> * Updated patch description based on Jarkko's feedback.
>>>
>>> Nayna Jain (3):
>>>    certs: export load_certificate_list() to be used outside certs/
>>>    integrity: make integrity_keyring_from_id() non-static
>>>    integrity: support including firmware ".platform" keys at build time
>>>
>>>   certs/Makefile                                |  5 ++--
>>>   certs/blacklist.c                             |  1 -
>>>   certs/common.c                                |  2 +-
>>>   certs/common.h                                |  9 -------
>>>   certs/system_keyring.c                        |  1 -
>>>   include/keys/system_keyring.h                 |  6 +++++
>>>   security/integrity/Kconfig                    | 10 +++++++
>>>   security/integrity/Makefile                   | 15 ++++++++++-
>>>   security/integrity/digsig.c                   |  2 +-
>>>   security/integrity/integrity.h                |  6 +++++
>>>   .../integrity/platform_certs/platform_cert.S  | 23 ++++++++++++++++
>>>   .../platform_certs/platform_keyring.c         | 26 +++++++++++++++++++
>>>   12 files changed, 90 insertions(+), 16 deletions(-)
>>>   delete mode 100644 certs/common.h
>>>   create mode 100644 security/integrity/platform_certs/platform_cert.S
>>>
>>>
>>> base-commit: c9e54f38976a1c0ec69c0a6208b3fd55fceb01d1
>>> -- 
>>> 2.27.0
>> Thank you, applied.
>>
>> BR, Jarkko
> You need to fix this:
>
> WARNING: externs should be avoided in .c files
> #129: FILE: security/integrity/platform_certs/platform_keyring.c:19:
> +extern __initconst const unsigned long platform_certificate_list_size;

Yes, because I followed the same convention as used for system keyring 
certs. Following externs are defined in system_keyring.c for referencing 
variables defined in .S file.

extern __initconst const u8 system_certificate_list[];
extern __initconst const unsigned long system_certificate_list_size;
extern __initconst const unsigned long module_cert_size;

Thanks & Regards,

     - Nayna