F19 DVD over size - what to drop?

Florian Weimer fweimer at redhat.com
Fri May 10 08:14:19 UTC 2013

On 05/06/2013 02:09 AM, Lars Seipel wrote:
> On Sat, May 04, 2013 at 01:03:11AM -0500, Chris Adams wrote:
>> However, unless your installer image is signed, checking RPM signatures
>> in anaconda is pointless (which is why the feature you mentioned is
>> based on Secure Boot).  If someone was going to the trouble of changing
>> the RPM signatures, they could also change the public keys included in
>> anaconda.
> Hmm.
> - the checksums for netinstall images are signed with a Fedora key
> - the corresponding public key is made available through https
> - therefore the integrity of installer images can be verified
> Obtaining an SSL certificate for fedoraproject.org shouldn't be much
> easier than getting your code signed to run under Secure Boot.

Actually, it should be practically indefeasible to obtain a certificate 
for fedoraproject.org from a browser CA without consent from the Fedora 
project (or Red Hat).  There have been several incidents where 
certificates were issued in a non-compliant manner by browser CAs, but 
there are guidelines, processes and compliance audits which aim to 
reduce such risks.

In contrast, the Microsoft signing process for third party UEFI drivers 
has no safeguards whatever to prevent anyone from getting a signature on 
something that poses as a Fedora installer (or Windows installer, for 
that matter).  This is not Microsoft's fault—it is just not evident from 
a first stage boot loader what it will eventually boot.  And from a user 
point of view, all UEFI driver signatures are alike because they do not 
embed a cleartext developer name.  (Not that UEFI firmware has 
Authenticode prompts which show the certificate on the driver.)

Florian Weimer / Red Hat Product Security Team

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