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hwrng: add randomness to system from rng sources 

When bringing a new RNG source online, it seems like it would make sense
to use some of its bytes to make the system entropy pool more random,
as done with all sorts of other devices that contain per-device or
per-boot differences.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Kees Cook 2014-03-03 15:51:48 -08:00 committed by followmsi
parent a303e3006b
commit 3f674bdd8d
1 changed files with 7 additions and 0 deletions
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7
drivers/char/hw_random/core.c
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@ -41,6 +41,7 @@
#include <linux/miscdevice.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <asm/uaccess.h>
@ -304,6 +305,8 @@ int hwrng_register(struct hwrng *rng)
{
int err = -EINVAL;
struct hwrng *old_rng, *tmp;
unsigned char bytes[16];
int bytes_read;
if (rng->name == NULL ||
(rng->data_read == NULL && rng->read == NULL))
@ -344,6 +347,10 @@ int hwrng_register(struct hwrng *rng)
}
INIT_LIST_HEAD(&rng->list);
list_add_tail(&rng->list, &rng_list);
bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
if (bytes_read > 0)
add_device_randomness(bytes, bytes_read);
out_unlock:
mutex_unlock(&rng_mutex);
out: