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

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Date:   Tue, 22 Nov 2022 10:36:06 +0800
From:   Coiby Xu <coxu@...hat.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>
Cc:     kexec@...ts.infradead.org, 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 Mimi,

On Mon, Nov 21, 2022 at 01:23:57PM -0500, Mimi Zohar wrote:
>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(),

Applied to v2, thanks for correcting me! Btw, I realize I overwrote the
return code of kexec_image_verify_sig with
mandate_signature_verification's. v2 has fixed this issue as well.

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

And thanks for the review!

-- 
Best regards,
Coiby

-- 
Best regards,
Coiby