From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64C9CC433EF for ; Thu, 23 Jun 2022 16:53:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232173AbiFWQxM (ORCPT ); Thu, 23 Jun 2022 12:53:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48860 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233898AbiFWQvu (ORCPT ); Thu, 23 Jun 2022 12:51:50 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4723A1836E; Thu, 23 Jun 2022 09:51:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D2CFB61F62; Thu, 23 Jun 2022 16:51:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE87CC3411B; Thu, 23 Jun 2022 16:51:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656003073; bh=JSoo2I+FLqaxpq8hlxGw0xxzJdzIaMJ0m4apH8OdkLo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=B0ufiFxQQUdHYOIuP8A+HSZqOb2Bd+QBv+plVXfbyabnCNuHv+OxFGarHFgzZNOJb td74Tw7mY0TSThjieMABnprpUHHurR29A/aOUEc4ELaj5KdaKSai8O+G5ijvK3InOq bGe1WiqzsfSLsDVy0UzE4zzu9ouURz7WpYbuLR6Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , Dominik Brodowski , Eric Biggers , "Jason A. Donenfeld" Subject: [PATCH 4.9 120/264] random: ensure early RDSEED goes through mixer on init Date: Thu, 23 Jun 2022 18:41:53 +0200 Message-Id: <20220623164347.462626883@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220623164344.053938039@linuxfoundation.org> References: <20220623164344.053938039@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: "Jason A. Donenfeld" commit a02cf3d0dd77244fd5333ac48d78871de459ae6d upstream. Continuing the reasoning of "random: use RDSEED instead of RDRAND in entropy extraction" from this series, at init time we also don't want to be xoring RDSEED directly into the crng. Instead it's safer to put it into our entropy collector and then re-extract it, so that it goes through a hash function with preimage resistance. As a matter of hygiene, we also order these now so that the RDSEED byte are hashed in first, followed by the bytes that are likely more predictable (e.g. utsname()). Cc: Theodore Ts'o Reviewed-by: Dominik Brodowski Reviewed-by: Eric Biggers Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- drivers/char/random.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1260,24 +1260,18 @@ int __init rand_initialize(void) bool arch_init = true; unsigned long rv; - mix_pool_bytes(&now, sizeof(now)); for (i = BLAKE2S_BLOCK_SIZE; i > 0; i -= sizeof(rv)) { - if (!arch_get_random_seed_long(&rv) && - !arch_get_random_long(&rv)) - rv = random_get_entropy(); - mix_pool_bytes(&rv, sizeof(rv)); - } - mix_pool_bytes(utsname(), sizeof(*(utsname()))); - - extract_entropy(&primary_crng.state[4], sizeof(u32) * 12); - for (i = 4; i < 16; i++) { if (!arch_get_random_seed_long_early(&rv) && !arch_get_random_long_early(&rv)) { rv = random_get_entropy(); arch_init = false; } - primary_crng.state[i] ^= rv; + mix_pool_bytes(&rv, sizeof(rv)); } + mix_pool_bytes(&now, sizeof(now)); + mix_pool_bytes(utsname(), sizeof(*(utsname()))); + + extract_entropy(&primary_crng.state[4], sizeof(u32) * 12); if (arch_init && trust_cpu && crng_init < 2) { invalidate_batched_entropy(); crng_init = 2;