From: Stephan Mueller Subject: Re: [RFC][PATCH] RANDOM: ATH9K RNG delivers zero bits of entropy Date: Sat, 06 Aug 2016 22:03:58 +0200 Message-ID: <6481670.KeU7RXkv1k@myon.chronox.de> References: <34197429.2CvoIfft9B@positron.chronox.de> <20160806194551.GA4511@io.lakedaemon.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: Ted Tso , herbert@gondor.apana.org.au, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, ath9k-devel@qca.qualcomm.com, linux-wireless@vger.kernel.org, ath9k-devel@lists.ath9k.org, Kalle Valo To: Jason Cooper Return-path: Received: from mail.eperm.de ([89.247.134.16]:34174 "EHLO mail.eperm.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751059AbcHFUEF (ORCPT ); Sat, 6 Aug 2016 16:04:05 -0400 In-Reply-To: <20160806194551.GA4511@io.lakedaemon.net> Sender: linux-crypto-owner@vger.kernel.org List-ID: Am Samstag, 6. August 2016, 19:45:51 CEST schrieb Jason Cooper: Hi Jason, > Hi Stephan, > > On Fri, Aug 05, 2016 at 05:08:14PM +0200, Stephan Mueller wrote: > > Hi Ted, Herbert, > > > > I sent a question to the ATH9K RNG some time ago to the developers. > > See > > https://www.mail-archive.com/linux-crypto@vger.kernel.org/msg19115.html > > > > I have not yet received a word and I think this issue should be resolved. > > > > Thanks > > Stephan > > > > ---8<--- > > If the above text is placed below the three dashes, "---", below ... > > > The ATH9K driver implements an RNG which is completely bypassing the > > standard Linux HW generator logic. > > > > The RNG may or may not deliver entropy. Considering the conservative > > approach in treating entropy with respect to non-auditable sources, this > > patch changes the delivered entropy value to zero. The RNG still feeds > > data into the input_pool but it is assumed to have no entropy. > > > > When the ATH9K RNG changes to use the HW RNG framework, it may re-enable > > the entropy estimation considering that a user can change that value at > > boot and runtime. > > > > Signed-off-by: Stephan Mueller > > --- > > here, then the mail can be applied directly without editing. Thank you for the hint. I will resend the patch that can be applied. > > > drivers/net/wireless/ath/ath9k/rng.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/drivers/net/wireless/ath/ath9k/rng.c > > b/drivers/net/wireless/ath/ath9k/rng.c index d38e50f..d63dc48 100644 > > --- a/drivers/net/wireless/ath/ath9k/rng.c > > +++ b/drivers/net/wireless/ath/ath9k/rng.c > > @@ -92,8 +92,7 @@ static int ath9k_rng_kthread(void *data) > > > > fail_stats = 0; > > > > /* sleep until entropy bits under write_wakeup_threshold */ > > > > - add_hwgenerator_randomness((void *)rng_buf, bytes_read, > > - ATH9K_RNG_ENTROPY(bytes_read)); > > This is the only use of this macro. I'd remove the #define on line 25 > as well. My idea for leaving it was that folks who would bring the RNG into the hwrandom framework could reuse the ideas from the original authors. What about commenting it out with #if 0 ? > > > + add_hwgenerator_randomness((void *)rng_buf, bytes_read, 0); > > > > } > > > > kfree(rng_buf); > > Other than that, > > Reviewed-by: Jason Cooper Thank you. > > thx, > > Jason. -- Ciao Stephan