From ec8f02da9ea500474417d1d31fa3d46a562ab366 Mon Sep 17 00:00:00 2001
From: Jarod Wilson <jarod@redhat.com>
Date: Tue, 6 Nov 2012 10:42:42 -0500
Subject: [PATCH] random: prime last_data value per fips requirements
The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
first use, either on system startup or after an RNDCLEARPOOL ioctl, we
need to take an initial random sample, store it internally in last_data,
then pass along the value after that to the requester, so that consistency
checks aren't being run against stale and possibly known data.
CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: "David S. Miller" <davem@davemloft.net>
CC: Matt Mackall <mpm@selenic.com>
CC: linux-crypto@vger.kernel.org
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
drivers/char/random.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index a1af1839576b..85e81ec1451e 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -433,6 +433,7 @@ struct entropy_store {
int entropy_count;
int entropy_total;
unsigned int initialized:1;
+ bool last_data_init;
__u8 last_data[EXTRACT_SIZE];
};
@@ -953,6 +954,10 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
ssize_t ret = 0, i;
__u8 tmp[EXTRACT_SIZE];
+ /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
+ if (fips_enabled && !r->last_data_init)
+ nbytes += EXTRACT_SIZE;
+
trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, min, reserved);
@@ -963,6 +968,17 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
if (fips_enabled) {
unsigned long flags;
+
+ /* prime last_data value if need be, per fips 140-2 */
+ if (!r->last_data_init) {
+ spin_lock_irqsave(&r->lock, flags);
+ memcpy(r->last_data, tmp, EXTRACT_SIZE);
+ r->last_data_init = true;
+ nbytes -= EXTRACT_SIZE;
+ spin_unlock_irqrestore(&r->lock, flags);
+ extract_buf(r, tmp);
+ }
+
spin_lock_irqsave(&r->lock, flags);
if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
panic("Hardware RNG duplicated output!\n");
@@ -1082,6 +1098,7 @@ static void init_std_data(struct entropy_store *r)
r->entropy_count = 0;
r->entropy_total = 0;
+ r->last_data_init = false;
mix_pool_bytes(r, &now, sizeof(now), NULL);
for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof(rv)) {
if (!arch_get_random_long(&rv))
--
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