Re: [PATCH 0/4] Fix misused kernel_read_file() enums

From: Hans de Goede <hdegoede@redhat.com>
To: Kees Cook <keescook@chromium.org>, James Morris <jmorris@namei.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
	Mimi Zohar <zohar@linux.ibm.com>,
	Scott Branden <scott.branden@broadcom.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Jessica Yu <jeyu@kernel.org>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Casey Schaufler <casey@schaufler-ca.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Matthew Garrett <matthewgarrett@google.com>,
	David Howells <dhowells@redhat.com>,
	Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	"Joel Fernandes (Google)" <joel@joelfernandes.org>,
	KP Singh <kpsingh@google.com>, Dave Olsthoorn <dave@bewaar.me>,
	Peter Jones <pjones@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Stephen Boyd <stephen.boyd@linaro.org>,
	Paul Moore <paul@paul-moore.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org
Subject: Re: [PATCH 0/4] Fix misused kernel_read_file() enums
Date: Wed, 8 Jul 2020 13:01:51 +0200	[thread overview]
Message-ID: <3c01073b-c422-dd97-0677-c16fe1158907@redhat.com> (raw)
In-Reply-To: <20200707081926.3688096-1-keescook@chromium.org>

Hi,

On 7/7/20 10:19 AM, Kees Cook wrote:
> Hi,
> 
> In looking for closely at the additions that got made to the
> kernel_read_file() enums, I noticed that FIRMWARE_PREALLOC_BUFFER
> and FIRMWARE_EFI_EMBEDDED were added, but they are not appropriate
> *kinds* of files for the LSM to reason about. They are a "how" and
> "where", respectively. Remove these improper aliases and refactor the
> code to adapt to the changes.
> 
> Additionally adds in missing calls to security_kernel_post_read_file()
> in the platform firmware fallback path (to match the sysfs firmware
> fallback path) and in module loading. I considered entirely removing
> security_kernel_post_read_file() hook since it is technically unused,
> but IMA probably wants to be able to measure EFI-stored firmware images,
> so I wired it up and matched it for modules, in case anyone wants to
> move the module signature checks out of the module core and into an LSM
> to avoid the current layering violations.
> 
> This touches several trees, and I suspect it would be best to go through
> James's LSM tree.
> 
> Thanks!

I've done some quick tests on this series to make sure that
the efi embedded-firmware support did not regress.
That still works fine, so this series is;

Tested-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans

> 
> -Kees
> 
> Kees Cook (4):
>    firmware_loader: EFI firmware loader must handle pre-allocated buffer
>    fs: Remove FIRMWARE_PREALLOC_BUFFER from kernel_read_file() enums
>    fs: Remove FIRMWARE_EFI_EMBEDDED from kernel_read_file() enums
>    module: Add hook for security_kernel_post_read_file()
> 
>   drivers/base/firmware_loader/fallback_platform.c | 12 ++++++++++--
>   drivers/base/firmware_loader/main.c              |  5 ++---
>   fs/exec.c                                        |  7 ++++---
>   include/linux/fs.h                               |  3 +--
>   include/linux/lsm_hooks.h                        |  6 +++++-
>   kernel/module.c                                  |  7 ++++++-
>   security/integrity/ima/ima_main.c                |  6 ++----
>   7 files changed, 30 insertions(+), 16 deletions(-)
> 