Re: [PATCH 00/23] Crypto keys and module signing

From: David Howells
Date: Wed May 23 2012 - 10:21:35 EST


Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:

> That's pretty weird. Why not put the "@This Is A Crypto Signed
> Module\n" before the signature? Then module-size is implied: everything
> before that signature. The signature size is implied: everything after
> that signature.

This makes it simpler. No scanning required. The magic number can only be in
one place and you can find it by dead reckoning.

> In fact, I'd modify this slightly, to allow multiple signatures.
> This would work nicely with a deterministic strip. Find the signatures
> backward, and truncate as they fail.

Why would you want multiple signatures? That just complicates things. If
you're in FIPS mode, you probably have to panic if any of them fail.

I suppose I may as well punt the signature detection and removal to userspace
and pass the signature as an argument to init_module() as Dmitry suggested.
Then the signature need not be in the file at all (he wants to use an xattr or
hardware, I think). mkinitrd and rpmbuild/kernel spec have to be changed to
accommodate enablement of these patches, so why not module-init-tools, dracut
and busybox whilst we're at it?

David
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