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 X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40AC8C4320A for ; Mon, 9 Aug 2021 09:56:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2215860F92 for ; Mon, 9 Aug 2021 09:56:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233603AbhHIJ5K (ORCPT ); Mon, 9 Aug 2021 05:57:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:50774 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233528AbhHIJ5J (ORCPT ); Mon, 9 Aug 2021 05:57:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CCB6660F11; Mon, 9 Aug 2021 09:56:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628503009; bh=siHqB30+J8sLOp7pEGFo9z0ErNUa2pMXDyohhHMW7U8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kevZHtdJYJPiRj0NYnYLFNKteyuj7hA/3N6StyCDAJnl9mszdPiYnuhSH2mqjlnq4 WtYS5CV8PlkYUHLSys+qFSJbIJh84/P6OSbhYCAHeckZZuBQ/2NVw3u+GY++pu/xed l14Vq78Yr7dxIE2hki8H9zO0jo6NgQmwm3DfgomeezsJZ7yGAhQX1jiFDRnFx457nQ +HK/EnQDZW1XX6O5PBu4X/sR1VXruhpIdGGtz2hN4+9EEOKfyQU9DwNffq0QDFghHT lxYtXA121HNVgRoIU05N0p2enG/6gtH7nFUgNiY8mxJ814WTgXmO0XJsYoRASpqbnP dxaypa2KMthug== Date: Mon, 9 Aug 2021 12:56:47 +0300 From: Jarkko Sakkinen To: Ahmad Fatoum Cc: Sumit Garg , James Bottomley , Mimi Zohar , David Howells , kernel , James Morris , "Serge E. Hallyn" , Horia =?utf-8?Q?Geant=C4=83?= , Aymen Sghaier , Herbert Xu , "David S. Miller" , Udit Agarwal , Eric Biggers , Jan Luebbe , David Gstir , Richard Weinberger , Franck LENORMAND , "open list:ASYMMETRIC KEYS" , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , linux-integrity , Linux Kernel Mailing List , "open list:SECURITY SUBSYSTEM" Subject: Re: [PATCH 2/4] KEYS: trusted: allow trust sources to use kernel RNG for key material Message-ID: <20210809095647.7xcxjeot5gyvmlpj@kernel.org> References: <7b771da7b09a01c8b4da2ed21f05251ea797b2e8.1626885907.git-series.a.fatoum@pengutronix.de> <7537c853-3641-a6d3-91d8-70fea9f01a89@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7537c853-3641-a6d3-91d8-70fea9f01a89@pengutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Mon, Aug 09, 2021 at 09:52:20AM +0200, Ahmad Fatoum wrote: > Hello Sumit, > > On 22.07.21 08:31, Sumit Garg wrote: > > On Wed, 21 Jul 2021 at 22:19, Ahmad Fatoum wrote: > >> > >> The two existing trusted key sources don't make use of the kernel RNG, > >> but instead let the hardware that does the sealing/unsealing also > >> generate the random key material. While a previous change offers users > >> the choice to use the kernel RNG instead for both, new trust sources > >> may want to unconditionally use the kernel RNG for generating key > >> material, like it's done elsewhere in the kernel. > >> > >> This is especially prudent for hardware that has proven-in-production > >> HWRNG drivers implemented, as otherwise code would have to be duplicated > >> only to arrive at a possibly worse result. > >> > >> Make this possible by turning struct trusted_key_ops::get_random > >> into an optional member. If a driver leaves it NULL, kernel RNG > >> will be used instead. > >> > >> Signed-off-by: Ahmad Fatoum > >> --- > >> To: James Bottomley > >> To: Jarkko Sakkinen > >> To: Mimi Zohar > >> To: David Howells > >> Cc: James Morris > >> Cc: "Serge E. Hallyn" > >> Cc: "Horia Geantă" > >> Cc: Aymen Sghaier > >> Cc: Herbert Xu > >> Cc: "David S. Miller" > >> Cc: Udit Agarwal > >> Cc: Eric Biggers > >> Cc: Jan Luebbe > >> Cc: David Gstir > >> Cc: Richard Weinberger > >> Cc: Franck LENORMAND > >> Cc: Sumit Garg > >> Cc: keyrings@vger.kernel.org > >> Cc: linux-crypto@vger.kernel.org > >> Cc: linux-integrity@vger.kernel.org > >> Cc: linux-kernel@vger.kernel.org > >> Cc: linux-security-module@vger.kernel.org > >> --- > >> include/keys/trusted-type.h | 2 +- > >> security/keys/trusted-keys/trusted_core.c | 2 +- > >> 2 files changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h > >> index d89fa2579ac0..4eb64548a74f 100644 > >> --- a/include/keys/trusted-type.h > >> +++ b/include/keys/trusted-type.h > >> @@ -64,7 +64,7 @@ struct trusted_key_ops { > >> /* Unseal a key. */ > >> int (*unseal)(struct trusted_key_payload *p, char *datablob); > >> > >> - /* Get a randomized key. */ > >> + /* Optional: Get a randomized key. */ > >> int (*get_random)(unsigned char *key, size_t key_len); > >> > >> /* Exit key interface. */ > >> diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c > >> index 569af9af8df0..d2b7626cde8b 100644 > >> --- a/security/keys/trusted-keys/trusted_core.c > >> +++ b/security/keys/trusted-keys/trusted_core.c > >> @@ -334,7 +334,7 @@ static int __init init_trusted(void) > >> continue; > >> > >> get_random = trusted_key_sources[i].ops->get_random; > >> - if (trusted_kernel_rng) > >> + if (trusted_kernel_rng || !get_random) > >> get_random = kernel_get_random; > >> > > > > For ease of understanding, I would prefer to write it as: > > > > get_random = trusted_key_sources[i].ops->get_random ?: > > kernel_get_random; > > if (trusted_kernel_rng) > > get_random = kernel_get_random; > > > > With that: > > > > Acked-by: Sumit Garg > > I don't think it improves readability to split up the conditional. > At least I need to take a second pass over the code to understand > the second conditional. Ternary operators are pain to read, unless a super trivial case. I'd stick to what you did. /Jarkko