2015-03-18 07:26:25

by Keith Packard

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

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 <[email protected]>
---
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

2015-03-18 10:02:20

by Herbert Xu

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

On Wed, Mar 18, 2015 at 12:17:00AM -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 <[email protected]>

Patch applied. Thanks Keith!
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt