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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 7C80CC433E6 for ; Fri, 29 Jan 2021 20:02:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3AA6964E02 for ; Fri, 29 Jan 2021 20:02:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233159AbhA2UCS (ORCPT ); Fri, 29 Jan 2021 15:02:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233129AbhA2T7a (ORCPT ); Fri, 29 Jan 2021 14:59:30 -0500 Received: from mail-pg1-x52f.google.com (mail-pg1-x52f.google.com [IPv6:2607:f8b0:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E6FB0C06174A for ; Fri, 29 Jan 2021 11:58:24 -0800 (PST) Received: by mail-pg1-x52f.google.com with SMTP id r38so7368428pgk.13 for ; Fri, 29 Jan 2021 11:58:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amacapital-net.20150623.gappssmtp.com; s=20150623; h=content-transfer-encoding:from:mime-version:subject:date:message-id :references:cc:in-reply-to:to; bh=aPmRknrUXoM+y6mtZ5BJIoZ2z2YX2kZHPwEWyf5g8oc=; b=aGp6lfHXNFiIoLGHImiNQDdm/k9ZVdbPXLHXzyLRrq20nvxq0i4U/eIYXg1+udihlc 1AJqRM191iNRasbNF0tJetz0cEnR6xX+JGEI4M4ZO4XFEtLTMPoRtQONA1kUCPqT3bq7 VGh9DfPFhQ/FBR9e2uZGqQMlH6sdmeHA5lro8JgNwX+lWEwkja8X7ODQFTkrmK4b0Psn b6lSUJdAEwMkPKKlN8TF7msXr7KnUfDh4Q/4WDY1HGTZxFABmtNNmtvbpT/7yvwN64pD tOji7YJ+jm0mTT/zBekdF3XUHPrmMxFjZZrpxvyRA7cROMwzT1an3fAHQwL4nv5O03Dn xOrw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:content-transfer-encoding:from:mime-version :subject:date:message-id:references:cc:in-reply-to:to; bh=aPmRknrUXoM+y6mtZ5BJIoZ2z2YX2kZHPwEWyf5g8oc=; b=YKQem4tzzVR8s7f3H0IYhxG2ub+908cKgLzUTjzt+nvCnls3YgLJn6NoarGVqLEhd/ xjCfBjjlehA2MRHwOA2cPT0l7a0zj2hdfJMRtavZgNxQk/dDs3omd+8yC9QB+axahci9 p9PDMDthcwwtN/glFCQHCFzPkAsuAyDmPuKO5PDQA2Suv+QJV19MuYHP0YM9lwinL90i 9MQ7Ap9cYfRN0N8kpk3UnjC64Ajd1TZ12hMgRHpYzbfacbnKZkTwP2F0pLo9mYVZbYLa EPPASt1hcq1sdYZW0WkGf/tTIGdZNTnsn3glezKNrfvFd7t2nekpUm8zbztfZgzticiZ oFDw== X-Gm-Message-State: AOAM532faaLsHkXaimQco9ZQfxEs6KQpaP4UTCsjVVLznG4eZMQMkP/1 XP4Le9/6Z8QJcA5OETXjWTA+Zw== X-Google-Smtp-Source: ABdhPJyVSSMtq6GrB08WQhwRVajO1mCXK195f1+mqR1Nl8ENdGTgc77vzrwNYHLhtryRg06DbVCv0Q== X-Received: by 2002:a63:5116:: with SMTP id f22mr6162045pgb.162.1611950304487; Fri, 29 Jan 2021 11:58:24 -0800 (PST) Received: from ?IPv6:2600:1010:b04b:3f76:e5b1:55a0:5bce:dce3? ([2600:1010:b04b:3f76:e5b1:55a0:5bce:dce3]) by smtp.gmail.com with ESMTPSA id y10sm9771144pff.197.2021.01.29.11.58.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 Jan 2021 11:58:23 -0800 (PST) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Andy Lutomirski Mime-Version: 1.0 (1.0) Subject: Re: [PATCH v18 02/25] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection Date: Fri, 29 Jan 2021 11:58:21 -0800 Message-Id: <86F8CE62-A94B-46BD-9A29-DBE1CC14AA83@amacapital.net> References: <40a5a9b5-9c83-473d-5f62-a16ecde50f2a@intel.com> Cc: Yu-cheng Yu , x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu In-Reply-To: <40a5a9b5-9c83-473d-5f62-a16ecde50f2a@intel.com> To: Dave Hansen X-Mailer: iPhone Mail (18C66) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jan 29, 2021, at 11:42 AM, Dave Hansen wrote: >=20 > =EF=BB=BFOn 1/27/21 1:25 PM, Yu-cheng Yu wrote: >> + help >> + Control-flow protection is a hardware security hardening feature >> + that detects function-return address or jump target changes by >> + malicious code. >=20 > It's not really one feature. I also think it's not worth talking about > shadow stacks or indirect branch tracking in *here*. Leave that for > Documentation/. >=20 > Just say: >=20 > Control-flow protection is a set of hardware features which > place additional restrictions on indirect branches. These help > mitigate ROP attacks. >=20 > ... and add more in the IBT patches. >=20 >> Applications must be enabled to use it, and old >> + userspace does not get protection "for free". >> + Support for this feature is present on processors released in >> + 2020 or later. Enabling this feature increases kernel text size >> + by 3.7 KB. >=20 > Did any CPUs ever get released that have this? If so, name them. If > not, time to change this to 2021, I think. Zen 3 :)=