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Re: EFI in Debian



On Sat, 2012-07-07 at 08:46 -0600, Ansgar Burchardt wrote:
> Hi,
> 
> Ben Hutchings <ben@decadent.org.uk> writes:
> > 2. Upstream kernel support: when booted in Secure Boot mode, Linux would
> > only load signed kernel modules and disable the various debug interfaces
> > that allow code injection.  I'm aware that David Howells, Matthew
> > Garrett and others are working on this.
> 
> That makes dkms modules unusable when using secure boot.  I guess we
> would have to build binary packages for all supported kernel versions?

The Linux kernel hardly has a perfect security record, but signing code
that is too bad even for staging will be a quick route to blacklisting.
I would absolutely oppose signing out-of-tree modules with Debian keys.

> > 5. Key management policy.  Similar issues to archive signing keys, but
> > these keys also need to be available at build time.  (a) Should they be
> > held by package maintainers and/or the auto-builders for the relevant
> > architectures?  (b) sbuild and/or pbuilder will need to know how to
> > inject them into the build environment for the relevant packages.  (c)
> > How do we handle key replacement when exploitable code needs to be
> > blacklisted?
> 
> Do these need to be available when building the kernel packages or would
> it be possible to have the signatures in a separate package?

That is possible... but the installation process would be tricky.

> The latter
> would allow moving the signing off the auto-builders and having either
> a human maintainer or a dedicated system do so instead (so the
> auto-builders would not need access to the keys).  It would also allow
> signing modules provided in the maintainer upload.

It would also help sites to sign with their own PK, if they want to take
full advantage of Secure Boot.

Ben.

-- 
Ben Hutchings
When in doubt, use brute force. - Ken Thompson

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