linux-kernel - Re: [PATCH RFC 0/4] Add firmware signature file check

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Date:	Tue, 06 Nov 2012 08:01:16 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	David Howells <dhowells@...hat.com>
Cc:	Matthew Garrett <mjg59@...f.ucam.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>, joeyli <jlee@...e.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Rusty Russell <rusty@...tcorp.com.au>,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org
Subject: Re: [PATCH RFC 0/4] Add firmware signature file check

At Tue, 06 Nov 2012 00:01:52 +0000,
David Howells wrote:
> 
> Takashi Iwai <tiwai@...e.de> wrote:
> 
> > this is a patch series to add the support for firmware signature
> > check.  At this time, the kernel checks extra signature file (*.sig)
> > for each firmware, instead of embedded signature.
> > It's just a quick hack using the existing module signing mechanism,
> > thus provided only as a proof of concept for now.
> 
> There is another way to do this.  If you look at the patches I proposed to
> wrap keys in PE binaries, you'll find that that can handle PKCS#7 format
> messages as that's what's in the sort of signed PE binary we're dealing with.
> 
> You could use this to put the firmware inside a signed-data PKCS#7 message.

Yeah, embedding the signature is more straightforward.  Actually I
tried the embedded signature (just like module) at first, then a
couple of concerns arose:

- Legally unclear about "modifying" the firmware data or file,

- The signed firmware is no longer compatible with the older kernel,
  thus bad for distro packaging.


thanks,

Takashi
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