From: Jarod Wilson Subject: [PATCH] random: prime last_data value per fips requirements Date: Mon, 5 Nov 2012 16:00:10 -0500 Message-ID: <1352149210-4790-1-git-send-email-jarod@redhat.com> Cc: Jarod Wilson , Herbert Xu , "David S. Miller" , Neil Horman , Matt Mackall , linux-crypto@vger.kernel.org To: linux-kernel@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48147 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932926Ab2KEVBu (ORCPT ); Mon, 5 Nov 2012 16:01:50 -0500 Sender: linux-crypto-owner@vger.kernel.org List-ID: 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 CC: "David S. Miller" CC: Neil Horman CC: Matt Mackall CC: linux-crypto@vger.kernel.org Signed-off-by: Jarod Wilson --- drivers/char/random.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index b86eae9..24d17b8 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -437,6 +437,7 @@ struct entropy_store { int entropy_count; int entropy_total; unsigned int initialized:1; + bool last_data_init; __u8 last_data[EXTRACT_SIZE]; }; @@ -967,6 +968,15 @@ 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; + spin_unlock_irqrestore(&r->lock, flags); + continue; + } + spin_lock_irqsave(&r->lock, flags); if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) panic("Hardware RNG duplicated output!\n"); @@ -1086,6 +1096,7 @@ 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)) -- 1.7.1