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

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>

1 files changed, 6 insertions, 0 deletions

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())));
 }