Re: [PATCH v1] crypto: caam - set hwrng quality level

From: Oleksij Rempel
Date: Thu Aug 03 2017 - 05:27:12 EST

On 03.08.2017 09:48, Horia Geantă wrote:
On 8/3/2017 6:17 AM, Herbert Xu wrote:
On Wed, Aug 02, 2017 at 02:03:14PM +0000, Horia Geantă wrote:

Take CAAM's engine HWRNG: it can work both as a TRNG and as a
TRNG-seeded DRBG (that's how it's currently configured).
IIUC, both setups are fit as source for the entropy pool.

So which is it? If it's a DRBG then it should not be exposed through
the hwrng interface. Only TRNG should go through hwrng. DRBGs
can use the crypto rng API.

Right now it's configured as a DRBG.
If I read correctly, it doesn't matter it's using the internal TRNG for
(automated) seeding, it still shouldn't use hwrng.
This means it's broken since the very beginning:
e24f7c9e87d4 crypto: caam - hwrng support

- what is the security risk of this issue? For example system which use /dev/hwrng directly?
- And who will fix it?