releases/3.0.41/random-use-arch-specific-rng-to-initialize-the-entropy-store.patch

From 3e88bdff1c65145f7ba297ccec69c774afe4c785 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 22 Dec 2011 16:28:01 -0500
Subject: random: Use arch-specific RNG to initialize the entropy store

From: Theodore Ts'o <tytso@mit.edu>

commit 3e88bdff1c65145f7ba297ccec69c774afe4c785 upstream.

If there is an architecture-specific random number generator (such as
RDRAND for Intel architectures), use it to initialize /dev/random's
entropy stores.  Even in the worst case, if RDRAND is something like
AES(NSA_KEY, counter++), it won't hurt, and it will definitely help
against any other adversaries.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Link: http://lkml.kernel.org/r/1324589281-31931-1-git-send-email-tytso@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/char/random.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -965,6 +965,7 @@ EXPORT_SYMBOL(get_random_bytes);
  */
 static void init_std_data(struct entropy_store *r)
 {
+	int i;
 	ktime_t now;
 	unsigned long flags;
 
@@ -974,6 +975,11 @@ static void init_std_data(struct entropy
 
 	now = ktime_get_real();
 	mix_pool_bytes(r, &now, sizeof(now));
+	for (i = r->poolinfo->poolwords; i; i--) {
+		if (!arch_get_random_long(&flags))
+			break;
+		mix_pool_bytes(r, &flags, sizeof(flags));
+	}
 	mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
 }