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 4AEAAC433FE for ; Tue, 15 Nov 2022 21:01:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238703AbiKOVBD (ORCPT ); Tue, 15 Nov 2022 16:01:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36754 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238704AbiKOVAv (ORCPT ); Tue, 15 Nov 2022 16:00:51 -0500 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F6D82D1DB; Tue, 15 Nov 2022 13:00:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1668546050; x=1700082050; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=xNXRQeFXYRAOm6+Xp0IR39SUwaBcxozLGg7herY21Uw=; b=lsMLP5YEmDLIiClnND4hhrp8X142NLIRYPufiX9WA9b534Zf0UmGZN49 mIWgyOnz/rynybLDAqg6KzIXLUAnUJu/751Cj1c3uZlZtQ3ir7fczBcGN Z2vRCvdzgh2/I83jzrLhza50Of149TTYWeeyowHqINPUDHWl7AHXH6fe9 W8SZf0TOCAhq1NFIaKdVDypN5IrdWrF01AgA7aQdxizIwcqGjqscU/wHR YpUc9f6UaX9qhvmrBemYy0m0dGQK4fBgEGReKXOZ1Ky00GiXJk/7lrA3O 8p2Aoqt/lRdxCjlt1PWfAWd+di8q0WhHjaqaVbVKNteOeLXAr5tMG8sMr Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10532"; a="314181085" X-IronPort-AV: E=Sophos;i="5.96,166,1665471600"; d="scan'208";a="314181085" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Nov 2022 13:00:42 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10532"; a="813821204" X-IronPort-AV: E=Sophos;i="5.96,166,1665471600"; d="scan'208";a="813821204" Received: from dn-intelpc-071822.amr.corp.intel.com (HELO [10.212.229.216]) ([10.212.229.216]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Nov 2022 13:00:40 -0800 Message-ID: <93029063-4a68-d275-b437-12930e119347@intel.com> Date: Tue, 15 Nov 2022 13:00:40 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH v3 36/37] x86/cet/shstk: Add ARCH_CET_UNLOCK Content-Language: en-US To: Peter Zijlstra , "Edgecombe, Rick P" Cc: "bsingharora@gmail.com" , "hpa@zytor.com" , "Syromiatnikov, Eugene" , "rdunlap@infradead.org" , "keescook@chromium.org" , "dave.hansen@linux.intel.com" , "kirill.shutemov@linux.intel.com" , "Eranian, Stephane" , "linux-mm@kvack.org" , "fweimer@redhat.com" , "nadav.amit@gmail.com" , "jannh@google.com" , "dethoma@microsoft.com" , "rppt@linux.ibm.com" , "linux-arch@vger.kernel.org" , "kcc@google.com" , "bp@alien8.de" , "oleg@redhat.com" , "hjl.tools@gmail.com" , "Yang, Weijiang" , "Lutomirski, Andy" , "pavel@ucw.cz" , "arnd@arndb.de" , "tglx@linutronix.de" , "mike.kravetz@oracle.com" , "x86@kernel.org" , "linux-doc@vger.kernel.org" , "jamorris@linux.microsoft.com" , "rppt@kernel.org" , "john.allen@amd.com" , "mingo@redhat.com" , "Shankar, Ravi V" , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , "linux-api@vger.kernel.org" , "gorcunov@gmail.com" , "akpm@linux-foundation.org" References: <20221104223604.29615-1-rick.p.edgecombe@intel.com> <20221104223604.29615-37-rick.p.edgecombe@intel.com> <4273232513cd178be303d817b15e442703bda637.camel@intel.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/15/22 12:57, Peter Zijlstra wrote: > On Tue, Nov 15, 2022 at 08:01:12PM +0000, Edgecombe, Rick P wrote: >>>> + if (task != current) { >>>> + if (option == ARCH_CET_UNLOCK && >>>> IS_ENABLED(CONFIG_CHECKPOINT_RESTORE)) { >>> Why make this conditional on CRIU at all? >> Kees asked for it, I think he was worried about attackers using it to >> unlock and disable shadow stack. So wanted to lock it down to the >> maximum. > Well, distros will all have this stuff enabled no? So not much > protection in practise. Yeah, that's true for the distros. But, I would imagine that our more paranoid friends like the ChromeOS folks might appreciate this.