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

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Message-ID: <YiQYFvrKCr4fPpY4@iki.fi>
Date:   Sun, 6 Mar 2022 04:10:30 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Nayna <nayna@...ux.vnet.ibm.com>
Cc:     Nayna Jain <nayna@...ux.ibm.com>, 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 Sat, Mar 05, 2022 at 08:32:43PM -0500, Nayna wrote:
> 
> 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;

So why don't you do as the warning says and place them to integrity.h
for instance?

BR, Jarkko