From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 22 Dec 2011 21:28:01 +0000 (-0500)
Subject: random: Use arch-specific RNG to initialize the entropy store
X-Git-Tag: v3.2.27~59
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=1d1e71f1bd606f77b5e49d9077d6ce23d3f8fc06;p=karo-tx-linux.git

random: Use arch-specific RNG to initialize the entropy store

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: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 85da8740586b..30794779c523 100644
--- 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_store *r)
 
 	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())));
 }