Re: [PATCH v3 2/5] random,x86: Add arch_get_slow_rng_u64

Andy Lutomirski
2014-07-17T17:12:27Z

On Thu, Jul 17, 2014 at 9:39 AM, H. Peter Anvin <hpa@zytor.com> wrote:
> On 07/17/2014 03:33 AM, Theodore Ts'o wrote:
>> On Wed, Jul 16, 2014 at 09:55:15PM -0700, H. Peter Anvin wrote:
>>> On 07/16/2014 05:03 PM, Andy Lutomirski wrote:
>>>>>
>>>> I meant that prandom isn't using rdrand for early seeding.
>>>>
>>>
>>> We should probably fix that.
>>
>> It wouldn't hurt to explicitly use arch_get_random_long() in prandom,
>> but it does use get_random_bytes() in early seed, and for CPU's with
>> RDRAND present, we do use it in init_std_data() in
>> drivers/char/random.c, so prandom is already getting initialized via
>> an RNG (which is effectively a DRBG even if it doesn't pass all of
>> NIST's rules) which is derived from RDRAND.
>>
>
> I assumed he was referring to before alternatives. Not sure if we use
> prandom before that point, though.

Unless I'm reading the code wrong, the prandom_reseed_late call can
happen after userspace is running.

Anyway, I'm working on a near-complete rewrite of the guest part of all of this.

--Andy

>
> -hpa
>
>

--
Andy Lutomirski
AMA Capital Management, LLC