Spectre mitigation

Carter Schonwald carter.schonwald at gmail.com
Thu Jan 4 18:55:09 UTC 2018

With the caveat of that I maybe have no clue what I’m talking about ;) :

It’s a pretty epic attack/ side channel, but it still requires code

The kernel side channel more of an issue for vm providers

And the spectre one probably will most heavily impact security conscious
organizations that might be considering using tools like moby/ docker /
Linux containers / kubernetes / mesos/ etc which depend on OS level process
isolation etc for security.

My fuzzy understanding is that one  fix would be hardware support for per
process isolation of memory even in the context users / processes ... which
isn’t in any kit afaik.

I do like my code not being slow.  So it’s a dilemma :/

On Thu, Jan 4, 2018 at 11:51 AM Thomas Jakway <tjakway at nyu.edu> wrote:

> I'm gonna start reading through the spectre paper in a few minutes but...
> is this really the death knell for speculative execution on x86/64...? If
> so, GHC getting patched is going to be pretty low on everyone's list of
> priorities.
> On Jan 4, 2018 6:36 AM, "Carter Schonwald" <carter.schonwald at gmail.com>
> wrote:
>> The only impacted code is the code which should already be engineered to
>> be  side channel resistant... which already need to be written in a way
>> that has constant control flow and memory lookup.
>> This is just a new and very powerful side channel attack.  It would be
>> interesting and possibly useful to explore fascilities that enable marked
>> pieces of code to be compiled in ways that improve side channel
>> resistance.  But there’s so many different approaches that it’d be
>> difficult to protect against all of them at once for general programs.
>> I could be totally wrong, and I should read the spectre paper :)
>> I guess I just mean that vulnerable Data should be hardened, but only
>> when the cost makes sense.  Every security issue has some finite cost. The
>> sum of those security events cost must be weighed against the sum of the
>> costs of preventing them
>> On Thu, Jan 4, 2018 at 9:08 AM Demi Obenour <demiobenour at gmail.com>
>> wrote:
>>> The recent “Spectre” bug requires that speculative execution of indirect
>>> branches be disabled.  For GHC, this will require passing a flag to LLVM
>>> and fixing the NCG to emit suitable calling sequences.
>>> This will be a disaster for the STG execution model, because it disables
>>> CPU branch prediction for indirect calls and jumps.  This is a big argument
>>> in favor of doing a CPS→SSA conversion in the backend.
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