Commit 5b739ef8 authored by Neil Horman's avatar Neil Horman Committed by Herbert Xu
Browse files

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



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: default avatarNeil Horman <nhorman@tuxdriver.com>
Acked-by: default avatarMatt Mackall <mpm@selenic.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent b6f34d44

crypto/internal.h

+1 −6
Original line number Diff line number Diff line
@@ -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 {

drivers/char/random.c

+14 −0
Original line number Diff line number Diff line
@@ -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)

include/linux/fips.h

0 → 100644
+10 −0
Original line number Diff line number Diff line 
#ifndef _FIPS_H

#define _FIPS_H



#ifdef CONFIG_CRYPTO_FIPS

extern int fips_enabled;

#else

#define fips_enabled 0

#endif



#endif

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