[PATCH] hwrng: core - allow perfect entropy from hardware devices

[PATCH] hwrng: core - allow perfect entropy from hardware devices

[Keith Packard]

Hardware random number quality is measured from 0 (no entropy) to 1024
(perfect entropy). Allow hardware devices to assert the full range by
truncating the device-provided value at 1024 instead of 1023.

Signed-off-by: Keith Packard <keithp@keithp.com>
---
 drivers/char/hw_random/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 1500cfd..b726683 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -98,7 +98,8 @@ static inline int hwrng_init(struct hwrng *rng)
 	add_early_randomness(rng);
 
 	current_quality = rng->quality ? : default_quality;
-	current_quality &= 1023;
+	if (current_quality > 1024)
+		current_quality = 1024;
 
 	if (current_quality == 0 && hwrng_fill)
 		kthread_stop(hwrng_fill);
-- 
2.1.4

Re: [PATCH] hwrng: core - allow perfect entropy from hardware devices

[Herbert Xu]

On Tue, Mar 17, 2015 at 10:13:28PM -0700, Keith Packard wrote:
> Hardware random number quality is measured from 0 (no entropy) to 1024
> (perfect entropy). Allow hardware devices to assert the full range by
> truncating the device-provided value at 1024 instead of 1023.
> 
> Signed-off-by: Keith Packard <keithp@keithp.com>

Please cc all hwrng patches to linux-crypto@vger.kernel.org so that
it gets picked up by patchworks.  Thanks!
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH] hwrng: core - allow perfect entropy from hardware devices

[Keith Packard]

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Herbert Xu <herbert@gondor.apana.org.au> writes:

> Please cc all hwrng patches to linux-crypto@vger.kernel.org so that
> it gets picked up by patchworks.  Thanks!

Thanks! I didn't catch that in the MAINTAINERS file. Might be a good
thing to add?

-- 
-keith

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Re: [PATCH] hwrng: core - allow perfect entropy from hardware devices

[Herbert Xu]

On Wed, Mar 18, 2015 at 12:15:49AM -0700, Keith Packard wrote:
> Herbert Xu <herbert@gondor.apana.org.au> writes:
> 
> > Please cc all hwrng patches to linux-crypto@vger.kernel.org so that
> > it gets picked up by patchworks.  Thanks!
> 
> Thanks! I didn't catch that in the MAINTAINERS file. Might be a good
> thing to add?

I think we've already added this to the MAINTAINERS file but it was
done fairly recently.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt