From patchwork Tue Aug 31 14:40:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Lobakin X-Patchwork-Id: 12467485 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 476D4C43214 for ; Tue, 31 Aug 2021 14:42:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2E58060200 for ; Tue, 31 Aug 2021 14:42:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238529AbhHaOnS (ORCPT ); Tue, 31 Aug 2021 10:43:18 -0400 Received: from mga14.intel.com ([192.55.52.115]:4175 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238517AbhHaOnK (ORCPT ); Tue, 31 Aug 2021 10:43:10 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10093"; a="218205185" X-IronPort-AV: E=Sophos;i="5.84,366,1620716400"; d="scan'208";a="218205185" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2021 07:42:08 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,366,1620716400"; d="scan'208";a="498317032" Received: from irvmail001.ir.intel.com ([10.43.11.63]) by fmsmga008.fm.intel.com with ESMTP; 31 Aug 2021 07:42:03 -0700 Received: from alobakin-mobl.ger.corp.intel.com (psmrokox-mobl.ger.corp.intel.com [10.213.6.58]) by irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id 17VEfmfW002209; Tue, 31 Aug 2021 15:42:00 +0100 From: Alexander Lobakin To: linux-hardening@vger.kernel.org Cc: "Kristen C Accardi" , Kristen Carlson Accardi , Kees Cook , Masahiro Yamada , "H. Peter Anvin" , Jessica Yu , Nathan Chancellor , Nick Desaulniers , Marios Pomonis , Sami Tolvanen , Tony Luck , Ard Biesheuvel , Jesse Brandeburg , Lukasz Czapnik , "Marta A Plantykow" , Michal Kubiak , Michal Swiatkowski , Alexander Lobakin , linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [PATCH v6 kspp-next 06/22] x86/boot: Allow a "silent" kaslr random byte fetch Date: Tue, 31 Aug 2021 16:40:58 +0200 Message-Id: <20210831144114.154-7-alexandr.lobakin@intel.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210831144114.154-1-alexandr.lobakin@intel.com> References: <20210831144114.154-1-alexandr.lobakin@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org From: Kees Cook Under earlyprintk, each RNG call produces a debug report line. When shuffling hundreds of functions, this is not useful information (each line is identical and tells us nothing new). Instead, allow for a NULL "purpose" to suppress the debug reporting. Signed-off-by: Kees Cook Signed-off-by: Kristen Carlson Accardi Signed-off-by: Alexander Lobakin --- arch/x86/lib/kaslr.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/arch/x86/lib/kaslr.c b/arch/x86/lib/kaslr.c index a53665116458..2b3eb8c948a3 100644 --- a/arch/x86/lib/kaslr.c +++ b/arch/x86/lib/kaslr.c @@ -56,11 +56,14 @@ unsigned long kaslr_get_random_long(const char *purpose) unsigned long raw, random = get_boot_seed(); bool use_i8254 = true; - debug_putstr(purpose); - debug_putstr(" KASLR using"); + if (purpose) { + debug_putstr(purpose); + debug_putstr(" KASLR using"); + } if (has_cpuflag(X86_FEATURE_RDRAND)) { - debug_putstr(" RDRAND"); + if (purpose) + debug_putstr(" RDRAND"); if (rdrand_long(&raw)) { random ^= raw; use_i8254 = false; @@ -68,7 +71,8 @@ unsigned long kaslr_get_random_long(const char *purpose) } if (has_cpuflag(X86_FEATURE_TSC)) { - debug_putstr(" RDTSC"); + if (purpose) + debug_putstr(" RDTSC"); raw = rdtsc(); random ^= raw; @@ -76,7 +80,8 @@ unsigned long kaslr_get_random_long(const char *purpose) } if (use_i8254) { - debug_putstr(" i8254"); + if (purpose) + debug_putstr(" i8254"); random ^= i8254(); } @@ -86,7 +91,8 @@ unsigned long kaslr_get_random_long(const char *purpose) : "a" (random), "rm" (mix_const)); random += raw; - debug_putstr("...\n"); + if (purpose) + debug_putstr("...\n"); return random; }