linux-kernel - Re: Linux Firmware Signing

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Date:	Thu, 27 Aug 2015 10:57:23 -0000
From:	"David Woodhouse" <dwmw2@...radead.org>
To:	"David Howells" <dhowells@...hat.com>
Cc:	"Luis R. Rodriguez" <mcgrof@...e.com>, dhowells@...hat.com,
	"Mimi Zohar" <zohar@...ux.vnet.ibm.com>,
	"Andy Lutomirski" <luto@...capital.net>,
	"Kees Cook" <keescook@...omium.org>,
	"Roberts, William C" <william.c.roberts@...el.com>,
	"linux-security-module@...r.kernel.org" 
	<linux-security-module@...r.kernel.org>,
	linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
	"james.l.morris@...cle.com" <james.l.morris@...cle.com>,
	"serge@...lyn.com" <serge@...lyn.com>,
	"Vitaly Kuznetsov" <vkuznets@...hat.com>,
	"Paul Moore" <paul@...l-moore.com>,
	"Eric Paris" <eparis@...isplace.org>, selinux@...ho.nsa.gov,
	"Stephen Smalley" <sds@...ho.nsa.gov>,
	"Schaufler, Casey" <casey.schaufler@...el.com>,
	"Luis R. Rodriguez" <mcgrof@...not-panic.com>,
	"Dmitry Kasatkin" <dmitry.kasatkin@...il.com>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	"Peter Jones" <pjones@...hat.com>, "Takashi Iwai" <tiwai@...e.de>,
	dwmw2@...radead.org, "Ming Lei" <ming.lei@...onical.com>,
	"Joey Lee" <jlee@...e.de>,
	"Vojtěch Pavlík" <vojtech@...e.com>,
	"Kyle McMartin" <kyle@...nel.org>,
	"Seth Forshee" <seth.forshee@...onical.com>,
	"Matthew Garrett" <mjg59@...f.ucam.org>,
	"Johannes Berg" <johannes@...solutions.net>
Subject: Re: Linux Firmware Signing

See http://www.infradead.org/rpr.html


> Luis R. Rodriguez <mcgrof@...e.com> wrote:
>
>> "PKCS#7: Add an optional authenticated attribute to hold firmware name"
>> https://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/commit/?h=fwsign-pkcs7&id=1448377a369993f864915743cfb34772e730213good
>>
>>         1.3.6.1.4.1.2312.16     Linux kernel
>>         1.3.6.1.4.1.2312.16.2   - PKCS#7/CMS SignerInfo attribute types
>>         1.3.6.1.4.1.2312.16.2.1   - firmwareName
>>
>> I take it you are referring to this?
>
> Yes.
>
>> If we follow this model we'd then need something like:
>>
>>         1.3.6.1.4.1.2312.16.2.2   - seLinuxPolicyName
>>
>> That should mean each OID that has different file names would need to be
>> explicit about and have a similar entry on the registry. I find that
>> pretty
>> redundant and would like to avoid that if possible.
>
> firmwareName is easy for people to understand - it's the name the kernel
> asks
> for and the filename of the blob.  seLinuxPolicyName is, I think, a lot
> more
> tricky since a lot of people don't use SELinux, and most that do don't
> understand it (most people that use it aren't even really aware of it).
>
> If you can use the firmwareName as the SELinux/LSM key, I would suggest
> doing
> so - even if you dress it up as a path (/lib/firmware/<firmwareName>).
>
> David
>

In conversation with Mimi last week she was very keen on the model where
we load modules & firmware in such a fashion that the kernel has access to
the original inode -- by passing in a f2f, or in the firmware case by
doing the rd lookup directly. So surely you have all the SELinux labelling
you need?

-- 
dwmw2

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