[PATCH] Adding diversity for security

[Julian Lettner]

Thanks for your comments, Alp.
Regarding the static / global issue, I agree and I will try to take care of
it.

@Stephen, Andrei
What are your opinionson un-seeded / non-deterministic compilation?

PS: Our discussion does not get aggregated here:
http://llvm-reviews.chandlerc.com/D1803
Did I do something wrong? How can we change that?




On Wed, Jan 22, 2014 at 3:50 PM, Alp Toker <alp at nuanti.com> wrote:

> Stephen,
>
> I've looked a bit closer at the clang patch.
>
> I don't understand why this is global:
>
>   llvm::RandomNumberGenerator::SetSalt(SaltString);
>
> LLVM and clang have a strict library design so this would be unreliable
> for anything other than the simplest single-threaded sequential use modes.
>
> We're getting close to fixing the last remaining statics so it doesn't
> seem right to introduce a new one.
>
> Alp.
>
>
>
>
> On 22/01/2014 23:39, Alp Toker wrote:
>
>> On 22/01/2014 23:17, Stephen Crane wrote:
>>
>>> Here's the patch for LLVM: http://llvm-reviews.chandlerc.com/D1802 We
>>> ended up basing the RNG on the already integrated implementation of MD5, to
>>> avoid any external dependencies. We are really just waiting on review of
>>> the LLVM patch now that Julian has modified a few things to take care of a
>>> performance concern.
>>>
>>
>> That sounds good.
>>
>> David Majnemer has already done preliminary review of the clang patch and
>> it looks sane to me.
>>
>> It will additionally need user documentation explaining the purpose of
>> the feature and noting that stability is not guaranteed between different
>> revisions of the compiler, even with the same seed.
>>
>> It's my opinion that un-seeded / non-deterministic compilation shouldn't
>> be supported at all. If that isn't the case already would it be reasonable
>> change for you to accommodate?
>>
>> Apart from that, just blocked on the LLVM changes.
>>
>> Alp.
>>
>>
>>
>>
>>> - stephen
>>>
>>>
>>> On Wed, Jan 22, 2014 at 3:00 PM, Alp Toker <alp at nuanti.com <mailto:
>>> alp at nuanti.com>> wrote:
>>>
>>>     The clang side looks fine, but there's very little context as to
>>>     what's going on here so not possible to review it just like that.
>>>
>>>     The patch rebases to clang ToT fine but doesn't build due to
>>>     missing RNG facilities in LLVM -- could you give a refresher of
>>>     the status of that with a link? It's been long enough that not
>>>     everyone remembers the discussion.
>>>
>>>     The last I remember of the discussion was that linking to OpenSSL
>>>     can be painful, and it doesn't feel right as a dependency. What
>>>     are the other options for pseudo RNG and could we have a simpler
>>>     scheme?
>>>
>>>     That'll help get things moving.
>>>
>>>     Alp.
>>>
>>>
>>>
>>>     On 22/01/2014 21:48, Julian Lettner wrote:
>>>
>>>            Is there anything stopping this from going forward?
>>>
>>>         http://llvm-reviews.chandlerc.com/D1803
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>>>
>>>
>>>
>>
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