[PATCH] killswitch: add per-function short-circuit mitigation primitive

[Song Liu]

On Mon, May 18, 2026 at 2:29 PM Paul Moore <paul at paul-moore.com> wrote:
[...]
> In my opinion, making killswitch an LSM is more of a procedural item
> that deals with how we view a capability like killswitch.  I
> personally view killswitch as somewhat similar to Lockdown, which is
> why I made the suggestion.
>
> The use of kprobes, while an interesting idea, presents problems as
> allowing any kernel symbol to be killed introduces the potential for
> security regressions.  As a reminder, some LSMs, as well as other
> kernel subsystems, have mechanisms in place to restrict root and/or
> enforce one-way configuration locks; while many people equate "root"
> with full control, in many cases today that is not strictly correct.
>
> Yes, kprobes have been around for some time, this is not a new
> problem, but killswitch makes it far more convenient and accessible to
> do dangerous things with kprobes.  If killswitch makes it past the RFC
> stage without any significant changes to its kill mechanism, we may
> need to start considering more liberal usage of NOKPROBE_SYMBOL()
> which I think would be an unfortunate casualty.

I don't think we can use NOKPROBE_SYMBOL(). There are functions
that we don't want to killswitch, but still want to trace.

Thanks,
Song