linux-kernel - Re: What should the default lockdown mode be if the bootloader sentinel triggers sanitization?

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Message-ID: <12081.1485784892@warthog.procyon.org.uk>
Date:   Mon, 30 Jan 2017 14:01:32 +0000
From:   David Howells <dhowells@...hat.com>
To:     Matt Fleming <matt@...eblueprint.co.uk>
Cc:     dhowells@...hat.com, Peter Jones <pjones@...hat.com>,
        mjg59@...f.ucam.org, ard.biesheuvel@...aro.org,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        "H. Peter Anvin" <hpa@...or.com>, Michael Chang <mchang@...e.com>
Subject: Re: What should the default lockdown mode be if the bootloader sentinel triggers sanitization?

Matt Fleming <matt@...eblueprint.co.uk> wrote:

> > Matt argues, however, that boot_params->secure_boot should be propagated from
> > the bootloader and if the bootloader wants to set it, then we should skip the
> > check in efi_main() and go with the bootloader's opinion.  This is something
> > we probably want to do with kexec() so that the lockdown state is propagated
> > there.
>  
> Actually what I was arguing for was that if the boot loader wants to
> set it and bypass the EFI boot stub, e.g. by going via the legacy
> 64-bit entry point, startup_64, then we should allow that as well as
> setting the flag in the EFI boot stub.

That brings up another question:  Should the non-EFI entry points clear the
secure_boot mode flag and set a default?

David