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

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Date:   Fri, 9 Jun 2017 09:18:46 -0400
From:   Matt Brown <matt@...tt.com>
To:     Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Kees Cook <keescook@...omium.org>
Cc:     James Morris <james.l.morris@...cle.com>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>
Subject: Re: [kernel-hardening] Re: [PATCH v2 1/1] Add Trusted Path Execution
 as a stackable LSM

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@...ux.vnet.ibm.com> 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