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Date: Tue, 5 Jan 2016 15:57:58 -0800
From: Kees Cook <keescook@...omium.org>
To: "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Subject: Re: Introduction and task request

On Mon, Dec 21, 2015 at 3:16 AM, Reshetova, Elena
<elena.reshetova@...el.com> wrote:
>>> What would be the reasonable task for me to do?
>
>> I always suggest people work on stuff that interests them. Do you have any
>> specific areas you like working on, or exploits you'd like to see stopped?
>
> I guess ideally people subscribed to this list want all exploits to be stopped
> :) But seriously I don't have any preference at least for now. Since I will
> have to learn a lot in this area I want to start from something which would be
> a reasonable and useful for this project piece of work, that's why I was
> asking for suggestions.
>
>>> I am quite a newbie in proper kernel development work (but not a
>>> newbie in platform security), so please as initial task do not through
>>> to me the biggest dead animal out there with the task to revive it.
>
>>Heh, understood. We'll be happy to assist you through whatever parts you
>>might want help with.
>
> Thank you!
>
>>> It is going to be a learning exercise for me at least at the
>>> beginning, but I am hoping to learn fast and start bringing value to the
>>> project.
>
>>I had mentioned PAX_USERCOPY earlier. I'm not sure how much work that'll be,
>>but extracting it would be the first step, and you can go from there. There's
>>no one actively working on it at the moment, and it would be very nice to
>>have.
>
> Casey is taking care of that, so I will leave it to him.
>
>> Or perhaps looking into the prior BPF_HARDEN work (currently this just
>> disables eBPF, but it used to try to defend against trivial heap-sprays).
>
>  This sounds smth that I can look into. I will be back when I have something
> reasonable ready or researched enough for sensible questions/discussion
> points. I will be away for long holidays until Jan 10, but hoping to return
> with plenty of energy :)

The original name was JIT_HARDEN, prior to grsecurity's 3.16 patches
(which just disable JIT entirely):
https://github.com/slashbeast/grsecurity-scrape/blob/master/test/grsecurity-3.0-3.15.5-201407170639.patch

I think it'd be nice to have the the JIT hardening feature, since it
does block heap-sprayed immediate values and probably other stuff, but
I haven't studied it.

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security

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