linux-kernel - Re: [PATCH v1 2/2] kexec: Introduce kexec_reboot

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Date:   Tue, 29 Nov 2022 09:32:45 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Philipp Rudo <prudo@...hat.com>
Cc:     Ricardo Ribalda <ribalda@...omium.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Jonathan Corbet <corbet@....net>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
        Ross Zwisler <zwisler@...nel.org>, linux-doc@...r.kernel.org,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>
Subject: Re: [PATCH v1 2/2] kexec: Introduce kexec_reboot_disabled

On Tue, 29 Nov 2022 14:44:50 +0100
Philipp Rudo <prudo@...hat.com> wrote:

> An alternative approach and sort of compromise I see is to convert
> kexec_load_disabled from a simple on/off switch to a counter on how
> often a kexec load can be made (in practice a tristate on/off/one-shot
> should be sufficient). Ideally the reboot and panic path will
> have separate counters. With that you could for example use
> kexec_load_limit.reboot=0 and kexec_load_limit.panic=1 to disable the
> load of images for reboot while still allow to load a crash kernel
> once. With this you have the flexibility you need while also preventing
> a race where an attacker overwrites your crash kernel before you can
> toggle the switch. What do you think?

I actually like this idea :-)

-- Steve