linux-kernel - Re: [PATCH v1] crypto: caam

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Message-ID: <8c0a88cd-8ce0-3752-d17a-9e78ff05b640@pengutronix.de>
Date:   Thu, 3 Aug 2017 11:26:57 +0200
From:   Oleksij Rempel <ore@...gutronix.de>
To:     Horia Geantă <horia.geanta@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Harald Freudenberger <freude@...ux.vnet.ibm.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Oleksij Rempel <o.rempel@...gutronix.de>,
        Dan Douglass <dan.douglass@....com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v1] crypto: caam - set hwrng quality level



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

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