Re: [kernel-hardening] Re: [PATCH v2 1/1] Add Trusted Path Execution as a stackable LSM

From: Matt Brown
Date: Fri Jun 09 2017 - 09:19:25 EST


On 6/9/17 9:16 AM, Mimi Zohar wrote:
> On Fri, 2017-06-09 at 05:55 -0700, Kees Cook wrote:
>> On Fri, Jun 9, 2017 at 3:18 AM, Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> wrote:
>>> On Thu, 2017-06-08 at 23:50 -0400, Matt Brown wrote:
>>>>>>
>>>>>> * Issues:
>>>>>> * Can be bypassed by interpreted languages such as python. You can run
>>>>>> malicious code by doing: python -c 'evil code'
>>>>>
>>>>> What's the recommendation for people interested in using TPE but
>>>>> having interpreters installed?
>>>>>
>>>>
>>>> If you don't need a given interpreter installed, uninstall it. While
>>>> this is common sense system hardening it especially would make a
>>>> difference under the TPE threat model.
>>>>
>>>> I don't have a knock down answer for this. Interpreters are a hard
>>>> problem for TPE.
>>>
>>> You might be interested in the minor LSM named "shebang", that I
>>> posted as a proof of concept back in January, which restricts the
>>> python interactive prompt/interpreter, but allows the scripts
>>> themselves to be executed.
>>
>> https://patchwork.kernel.org/patch/9547405/
>>
>> Maybe these could be merged and the interpreter string could be made
>> into a configurable list?
>
> I updated shebang, but didn't bother to post it, as nobody seemed to
> be interested at the time. The updated version already has support
> for the configurable list. Re-posting ...
>

That would be awesome. I think it's the perfect complement to TPE as it
protects a key hole in its current threat model.

Matt