Re: [RFD] linux-firmware key arrangement for firmware signing

Mimi Zohar
2015-05-21T13:06:24Z

On Wed, 2015-05-20 at 23:14 -0700, Greg Kroah-Hartman wrote:
> On Thu, May 21, 2015 at 08:41:02AM +0300, Petko Manolov wrote:
> > > I too don't understand this need to sign something that you don't really know
> > > what it is from some other company, just to send it to a separate device that
> > > is going to do whatever it wants with it if it is signed or not.
> >
> > This is not the point. What you need to know is _where_ the firmware came from,
> > not _what_ it does once it reach your system. If you don't care about such
> > things, just ignore the signature. :)
>
> Ok, but how do we know "where"? Who is going to start signing and
> attesting to the validity of all of the firmware images in the
> linux-firmware tree suddenly? Why is it the kernel's job to attest this
> "where"? Shouldn't your distro/manufacturer be doing that as part of
> their "put this file on this disk" responsibilities (i.e. the package
> manager?)

Signatures don't provide any guarantees as to code quality or
correctness. They do provide file integrity and provenance. In
addition to the license and a Signed-off-by line, having the firmware
provider include a signature of the firmware would be nice.

> What is verifying a firmware image signature in the kernel attesting
> that isn't already known in userspace?

Appraising and enforcing firmware integrity before use.

Mimi