linux-kernel - Re: [PATCH] lockdown: kexec_file: prevent unsigned kernel image when KEXEC

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Date:   Mon, 21 Nov 2022 13:23:57 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Coiby Xu <coxu@...hat.com>, kexec@...ts.infradead.org
Cc:     Matthew Garrett <mjg59@...f.ucam.org>, Jiri Bohac <jbohac@...e.cz>,
        David Howells <dhowells@...hat.com>,
        linux-integrity@...r.kernel.org,
        Eric Biederman <ebiederm@...ssion.com>,
        James Morris <jmorris@...ei.org>,
        Matthew Garrett <mjg59@...gle.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] lockdown: kexec_file: prevent unsigned kernel image
 when KEXEC_SIG not enabled

Hi Coiby,

On Mon, 2022-11-21 at 15:29 +0800, Coiby Xu wrote:
> A kernel builder may not enable KEXEC_SIG and some architectures like
> ppc64 simply don't have KEXEC_SIG. In these cases, unless both
> IMA_ARCH_POLICY and secure boot also enabled, lockdown doesn't prevent
> unsigned kernel image from being kexec'ed via the kexec_file_load
> syscall whereas it could prevent one via the kexec_load syscall. Mandate
> signature verification for those cases.
> 
> Fixes: 155bdd30af17 ("kexec_file: Restrict at runtime if the kernel is locked down")
> Cc: Matthew Garrett <mjg59@...f.ucam.org>
> Cc: Jiri Bohac <jbohac@...e.cz>
> Cc: David Howells <dhowells@...hat.com>
> Cc: kexec@...ts.infradead.org
> Cc: linux-integrity@...r.kernel.org
> Signed-off-by: Coiby Xu <coxu@...hat.com>

Other than correcting the function name to mandate_signature_verificati
on(),

Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>