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random: Add optional continuous repetition test to entropy store based rngs

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FIPS-140 requires that all random number generators implement continuous self
tests in which each extracted block of data is compared against the last block
for repetition.  The ansi_cprng implements such a test, but it would be nice if
the hw rng's did the same thing.  Obviously its not something thats always
needed, but it seems like it would be a nice feature to have on occasion. I've
written the below patch which allows individual entropy stores to be flagged as
desiring a continuous test to be run on them as is extracted.  By default this
option is off, but is enabled in the event that fips mode is selected during
bootup.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Neil Horman 2009-06-18 19:50:21 +08:00 committed by Herbert Xu
parent b6f34d44cb
commit 5b739ef8a4
3 changed files with 25 additions and 6 deletions
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7
crypto/internal.h
View file

@ -25,12 +25,7 @@
#include <linux/notifier.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#ifdef CONFIG_CRYPTO_FIPS
extern int fips_enabled;
#else
#define fips_enabled 0
#endif
#include <linux/fips.h>
/* Crypto notification events. */
enum {

14
drivers/char/random.c
View file

@ -240,6 +240,7 @@
#include <linux/spinlock.h>
#include <linux/percpu.h>
#include <linux/cryptohash.h>
#include <linux/fips.h>
#ifdef CONFIG_GENERIC_HARDIRQS
# include <linux/irq.h>
@ -413,6 +414,7 @@ struct entropy_store {
unsigned add_ptr;
int entropy_count;
int input_rotate;
__u8 *last_data;
};
static __u32 input_pool_data[INPUT_POOL_WORDS];
@ -852,12 +854,21 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
{
ssize_t ret = 0, i;
__u8 tmp[EXTRACT_SIZE];
unsigned long flags;
xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, min, reserved);
while (nbytes) {
extract_buf(r, tmp);
if (r->last_data) {
spin_lock_irqsave(&r->lock, flags);
if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
panic("Hardware RNG duplicated output!\n");
memcpy(r->last_data, tmp, EXTRACT_SIZE);
spin_unlock_irqrestore(&r->lock, flags);
}
i = min_t(int, nbytes, EXTRACT_SIZE);
memcpy(buf, tmp, i);
nbytes -= i;
@ -940,6 +951,9 @@ static void init_std_data(struct entropy_store *r)
now = ktime_get_real();
mix_pool_bytes(r, &now, sizeof(now));
mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
/* Enable continuous test in fips mode */
if (fips_enabled)
r->last_data = kmalloc(EXTRACT_SIZE, GFP_KERNEL);
}
static int rand_initialize(void)

10
include/linux/fips.h Normal file
View file

@ -0,0 +1,10 @@
#ifndef _FIPS_H
#define _FIPS_H
#ifdef CONFIG_CRYPTO_FIPS
extern int fips_enabled;
#else
#define fips_enabled 0
#endif
#endif