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: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/internal.h b/crypto/internal.h
index 113579a..95baaea 100644
--- a/crypto/internal.h
+++ b/crypto/internal.h
@@ -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 {
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 8c74448..d8a9255 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -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 @@
unsigned add_ptr;
int entropy_count;
int input_rotate;
+ __u8 *last_data;
};
static __u32 input_pool_data[INPUT_POOL_WORDS];
@@ -852,12 +854,21 @@
{
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 @@
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)
diff --git a/include/linux/fips.h b/include/linux/fips.h
new file mode 100644
index 0000000..f8fb07b
--- /dev/null
+++ b/include/linux/fips.h
@@ -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