From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753858AbdKHGMg (ORCPT ); Wed, 8 Nov 2017 01:12:36 -0500 Received: from mail-it0-f41.google.com ([209.85.214.41]:55795 "EHLO mail-it0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753783AbdKHGMc (ORCPT ); Wed, 8 Nov 2017 01:12:32 -0500 X-Google-Smtp-Source: ABhQp+QccoALgxIAybItjV1fhrP0opFH72VO8eQoUABEXu/pxIG8O5TG/x/cEvy98nVzzaM4KLQoSA== Date: Wed, 8 Nov 2017 15:15:54 +0900 From: "AKASHI, Takahiro" To: "Luis R. Rodriguez" Cc: Mimi Zohar , David Howells , linux-security-module@vger.kernel.org, gnomes@lxorguk.ukuu.org.uk, linux-efi , gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, Matthew Garrett Subject: Re: Firmware signing -- Re: [PATCH 00/27] security, efi: Add kernel lockdown Message-ID: <20171108061551.GD7859@linaro.org> Mail-Followup-To: "AKASHI, Takahiro" , "Luis R. Rodriguez" , Mimi Zohar , David Howells , linux-security-module@vger.kernel.org, gnomes@lxorguk.ukuu.org.uk, linux-efi , gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, Matthew Garrett References: <1509660086.3416.15.camel@linux.vnet.ibm.com> <150842463163.7923.11081723749106843698.stgit@warthog.procyon.org.uk> <14219.1509660259@warthog.procyon.org.uk> <1509660641.3416.24.camel@linux.vnet.ibm.com> <20171107230700.GJ22894@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20171107230700.GJ22894@wotan.suse.de> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Luis, Thank you for this heads-up. On Wed, Nov 08, 2017 at 12:07:00AM +0100, Luis R. Rodriguez wrote: > On Thu, Nov 02, 2017 at 06:10:41PM -0400, Mimi Zohar wrote: > > On Thu, 2017-11-02 at 22:04 +0000, David Howells wrote: > > > Mimi Zohar wrote: > > > > > > > > Only validly signed device firmware may be loaded. > > > > > > > > fw_get_filesystem_firmware() calls kernel_read_file_from_path() to > > > > read the firmware, which calls into the security hooks. Is there > > > > another place that validates the firmware signatures.  I'm not seeing > > > > which patch requires firmware to be signed? > > > > > > Luis has a set of patches for this. However, I'm not sure if that's going > > > anywhere at the moment. Possibly I should remove this from the manpage for > > > the moment. > > Remove it for now. The state of of affairs for firmware signing is complex given > that we first wanted to address how to properly grow the API without making > the API worse. This in and of itself was an effort, and that effort also > evaluated two different development paradigms: > > o functional API > o data driven API > > I only recently was convinced that functional API should be used, even for > commonly used exported symbols, Are you? I haven't answered Linus' question, but my concern about functional APIs, as far as firmware signing goes, is that we have no way to _enforce_ firmware signing to existing (i.e. verification-unaware) drivers if we need an explicit call of a function, say, verify_firmware(). > and as such I've been going back and slowly > grooming the firmware API with small atomic changes to first clean up the > complex flag mess we have. > > Since I'm busy with that Takahiro AKASHI has taken up firmware singing effort > but this will depend on the above small cleanup to be done first. I was busy > with addressing existing bugs on the firmware API for a while, then company > travel / conferences so was not able to address this, but I'm back now and > I believe I should be able to tackle the cleanup now. Good to hear. > Only after this is merged can we expect a final respin of the firmware signing > effort. > > > Or reflect that IMA-appraisal, if enabled, will enforce firmware being > > validly signed. > > But FWICT lockdown is a built-in kernel thingy, unless lockdown implies IMA > it would not be the place to refer to it. I think that the situation is the same as in module signing. -Takahiro AKASHI > It seems the documentation was proposed to help users if an error was caught. > That error should cover only what is being addressed in code on the kernel. > > Luis