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 D26A8C433F5 for ; Fri, 27 May 2022 12:02:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352228AbiE0MCe (ORCPT ); Fri, 27 May 2022 08:02:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352058AbiE0LtH (ORCPT ); Fri, 27 May 2022 07:49:07 -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 6367613CA31; Fri, 27 May 2022 04:44:02 -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 2D00361D6F; Fri, 27 May 2022 11:44:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39F06C385A9; Fri, 27 May 2022 11:44:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1653651841; bh=XxK0OtvwNhgUMCOyhriJ/+qNy/K+HjGgOW3wfyCgR3A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xJKFUIvPRkBwbQ4R9IU27Boaarc1ETTPtxix/DlcppZD4jbk2N3kKfsa3E7dNH5w+ Uw0gHapxM5iPWtZtHTZJWhlX/8ZuamkOkVISn1NOujCLlHZOqQA+3ZRfGv89lVje33 UOYqSoV/S2RYOq1uarU/hoZCyTUc/oPtuXMnBkgo= 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 5.15 049/145] random: ensure early RDSEED goes through mixer on init Date: Fri, 27 May 2022 10:49:10 +0200 Message-Id: <20220527084856.727135806@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220527084850.364560116@linuxfoundation.org> References: <20220527084850.364560116@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: linux-kernel@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 @@ -1208,24 +1208,18 @@ 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;