Re: [PATCH] kconfig: Add kernel config option for fuzz testing.

[Tetsuo Handa]

On 2020/01/03 4:57, Matthew Garrett wrote:
> On Tue, Dec 17, 2019 at 12:53 AM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
>> +Matthew for a lockdown question
>> We are considering [ab]using lockdown (you knew this will happen!) for
>> fuzzing kernel. LOCKDOWN_DEBUGFS is a no-go for us and we may want a
>> few other things that may be fuzzing-specific.
>> The current inflexibility comes from the global ordering of levels:
>>
>> if (kernel_locked_down >= level)
>> if (kernel_locked_down >= what) {
>>
>> Is it done for performance? Or for simplicity?
> 
> Simplicity. Based on discussion, we didn't want the lockdown LSM to
> enable arbitrary combinations of lockdown primitives, both because
> that would make it extremely difficult for userland developers and
> because it would make it extremely easy for local admins to
> accidentally configure policies that didn't achieve the desired
> outcome. There's no inherent problem in adding new options, but really
> right now they should fall into cases where they're protecting either
> the integrity of the kernel or preventing leakage of confidential
> information from the kernel.
> 

Can we resume this topic?

I think build-time lockdown (i.e. kernel config option) is more reliable
and easier to use.