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authorNeil Horman <nhorman@tuxdriver.com>2009-06-18 07:50:21 -0400
committerHerbert Xu <herbert@gondor.apana.org.au>2009-06-18 07:50:21 -0400
commit5b739ef8a4e8cf5201d21abff897e292c232477b (patch)
tree6301126016ad869997b4ef31973999e16049dfeb /drivers/char
parentb6f34d44cb341ad32f08717d1a2c418e6053a031 (diff)
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>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/random.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 8c7444857a4b..d8a9255e1a3f 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -240,6 +240,7 @@
240#include <linux/spinlock.h> 240#include <linux/spinlock.h>
241#include <linux/percpu.h> 241#include <linux/percpu.h>
242#include <linux/cryptohash.h> 242#include <linux/cryptohash.h>
243#include <linux/fips.h>
243 244
244#ifdef CONFIG_GENERIC_HARDIRQS 245#ifdef CONFIG_GENERIC_HARDIRQS
245# include <linux/irq.h> 246# include <linux/irq.h>
@@ -413,6 +414,7 @@ struct entropy_store {
413 unsigned add_ptr; 414 unsigned add_ptr;
414 int entropy_count; 415 int entropy_count;
415 int input_rotate; 416 int input_rotate;
417 __u8 *last_data;
416}; 418};
417 419
418static __u32 input_pool_data[INPUT_POOL_WORDS]; 420static __u32 input_pool_data[INPUT_POOL_WORDS];
@@ -852,12 +854,21 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
852{ 854{
853 ssize_t ret = 0, i; 855 ssize_t ret = 0, i;
854 __u8 tmp[EXTRACT_SIZE]; 856 __u8 tmp[EXTRACT_SIZE];
857 unsigned long flags;
855 858
856 xfer_secondary_pool(r, nbytes); 859 xfer_secondary_pool(r, nbytes);
857 nbytes = account(r, nbytes, min, reserved); 860 nbytes = account(r, nbytes, min, reserved);
858 861
859 while (nbytes) { 862 while (nbytes) {
860 extract_buf(r, tmp); 863 extract_buf(r, tmp);
864
865 if (r->last_data) {
866 spin_lock_irqsave(&r->lock, flags);
867 if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
868 panic("Hardware RNG duplicated output!\n");
869 memcpy(r->last_data, tmp, EXTRACT_SIZE);
870 spin_unlock_irqrestore(&r->lock, flags);
871 }
861 i = min_t(int, nbytes, EXTRACT_SIZE); 872 i = min_t(int, nbytes, EXTRACT_SIZE);
862 memcpy(buf, tmp, i); 873 memcpy(buf, tmp, i);
863 nbytes -= i; 874 nbytes -= i;
@@ -940,6 +951,9 @@ static void init_std_data(struct entropy_store *r)
940 now = ktime_get_real(); 951 now = ktime_get_real();
941 mix_pool_bytes(r, &now, sizeof(now)); 952 mix_pool_bytes(r, &now, sizeof(now));
942 mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); 953 mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
954 /* Enable continuous test in fips mode */
955 if (fips_enabled)
956 r->last_data = kmalloc(EXTRACT_SIZE, GFP_KERNEL);
943} 957}
944 958
945static int rand_initialize(void) 959static int rand_initialize(void)