linux-kernel - Re: [v2] RANDOM: ATH9K RNG delivers zero bits of entropy

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Date:   Tue, 27 Sep 2016 17:17:02 +0200
From:   Stephan Mueller <smueller@...onox.de>
To:     Kalle Valo <kvalo@....qualcomm.com>
Cc:     Ted Tso <tytso@....edu>, herbert@...dor.apana.org.au,
        linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        ath9k-devel@....qualcomm.com, linux-wireless@...r.kernel.org,
        ath9k-devel@...ts.ath9k.org, Kalle Valo <kvalo@...eaurora.org>,
        Jason Cooper <jason@...edaemon.net>
Subject: Re: [v2] RANDOM: ATH9K RNG delivers zero bits of entropy

Am Dienstag, 27. September 2016, 16:44:16 CEST schrieb Kalle Valo:

Hi Kalle,

> Stephan Mueller <smueller@...onox.de> wrote:
> > 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.
> > 
> > Reviewed-by: Jason Cooper <jason@...edaemon.net>
> > Signed-off-by: Stephan Mueller <smueller@...onox.de>
> 
> Based on the discussion I'm dropping this patch. But the discussion was
> hard to follow so please let me know if I misunderstood.

I guess the rejection is appropriate, but something needs to be done: 
add_hwgenerator_randomness should not be used in this scenario.
> 
> Patch set to Rejected.



Ciao
Stephan