Re: Linux Firmware Signing

[David Woodhouse <dwmw2@xxxxxxxxxxxxx>]

By passing in a fd... or doing the fs lookup directly. Bloody autocorrect. 

-- 
Apologies for HTML and top-posting; Android email is broken.

-------- Original Message --------
From:David Woodhouse
Sent:Thu, 27 Aug 2015 11:57:23 +0100
To:David Howells
Cc:"Luis R. Rodriguez" ,dhowells@xxxxxxxxxx,Mimi Zohar ,Andy Lutomirski ,Kees Cook ,"Roberts, William C" ,linux-security-module@xxxxxxxxxxxxxxx,linux-kernel@xxxxxxxxxxxxxxx,linux-wireless@xxxxxxxxxxxxxxx,james.l.morris@xxxxxxxxxx,serge@xxxxxxxxxx,Vitaly Kuznetsov ,Paul Moore ,Eric Paris ,selinux@xxxxxxxxxxxxx,Stephen Smalley ,"Schaufler, Casey" ,"Luis R. Rodriguez" ,Dmitry Kasatkin ,Greg Kroah-Hartman ,Peter Jones ,Takashi Iwai ,dwmw2@xxxxxxxxxxxxx,Ming Lei ,Joey Lee ,Vojtěch Pavlík ,Kyle McMartin ,Seth Forshee ,Matthew Garrett ,Johannes Berg
Subject:Re: Linux Firmware Signing

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


> Luis R. Rodriguez

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/).
>
> 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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