Re: [PATCH v3] killswitch: add per-function short-circuit mitigation primitive

Sasha Levin <[email protected]>
Newsgroups org.kernel.vger.live-patching,org.kernel.vger.bpf,org.kernel.vger.linux-doc,org.kernel.vger.linux-kernel,org.kernel.vger.linux-kselftest
Message-ID <ag8Y8L2WCcSEDPkG@laps>
On Tue, May 19, 2026 at 03:00:15PM -0700, Song Liu wrote:
>On Tue, May 19, 2026 at 12:57 PM Sasha Levin <[email protected]> wrote:
>[...]
>> >Fully agree with Song here that there is no clear boundary, and that the
>> >killswitch could lead to arbitrary, hard to debug breakage if applied to
>> >the wrong function.. introducing worse bugs than the one being mitigated
>> >or even /short-circuit LSM enforcement/ (engage security_file_open 0,
>> >engage cap_capable 0, engage apparmor_* etc).
>>
>> This is similar to livepatch, right? Do we need guardrails there too?
>
>livepatch has the same guardrails as other kernel modules:
>CONFIG_MODULE_SIG, CONFIG_MODULE_SIG_FORCE, etc.

Which the user can choose to enable or disable. Livepatches will work just fine
with CONFIG_MODULE_SIG=n, right?

With the whitelist approach, the user has no choice but to accept it.

Would it make sense to allow disabling the whitelist via a kernel config or
some runtime flag?

-- 
Thanks,
Sasha
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