From 3e88bdff1c65145f7ba297ccec69c774afe4c785 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Thu, 22 Dec 2011 16:28:01 -0500 Subject: 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" Link: http://lkml.kernel.org/r/1324589281-31931-1-git-send-email-tytso@mit.edu Signed-off-by: H. Peter Anvin --- drivers/char/random.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/random.c b/drivers/char/random.c index 85da8740586..30794779c52 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()))); } -- cgit v1.2.3 From 2dac8e54f988ab58525505d7ef982493374433c3 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Mon, 16 Jan 2012 11:23:29 -0800 Subject: random: Adjust the number of loops when initializing When we are initializing using arch_get_random_long() we only need to loop enough times to touch all the bytes in the buffer; using poolwords for that does twice the number of operations necessary on a 64-bit machine, since in the random number generator code "word" means 32 bits. Signed-off-by: H. Peter Anvin Cc: "Theodore Ts'o" Link: http://lkml.kernel.org/r/1324589281-31931-1-git-send-email-tytso@mit.edu --- drivers/char/random.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 30794779c52..9a2156d7762 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -975,7 +975,7 @@ 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--) { + for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof flags) { if (!arch_get_random_long(&flags)) break; mix_pool_bytes(r, &flags, sizeof(flags)); -- cgit v1.2.3