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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 314F0C433ED for ; Wed, 28 Apr 2021 15:01:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E53A6613BD for ; Wed, 28 Apr 2021 15:01:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231380AbhD1PCO (ORCPT ); Wed, 28 Apr 2021 11:02:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236071AbhD1PBu (ORCPT ); Wed, 28 Apr 2021 11:01:50 -0400 Received: from mail-oi1-x236.google.com (mail-oi1-x236.google.com [IPv6:2607:f8b0:4864:20::236]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E605C0612AD; Wed, 28 Apr 2021 07:57:15 -0700 (PDT) Received: by mail-oi1-x236.google.com with SMTP id d25so25800294oij.5; Wed, 28 Apr 2021 07:57:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=xU26eKhAat6ZuGhDgaDU4lA3EkxCkgm/s81rka2sejI=; b=k5jI8e0y1SuWfZ34di/qkLtVolNK2FRYo26+wf8LY5DibGsrSHDxJYhS8RKM0i+O43 0/dIqE+x2A+/sK3y3/wHosMr3rOsYPkD/ZOTo6CHe+FUahRCYdho1Yt6Jkz+s9b0Nys0 Vv8t5Q+QJjN8/RyO+vs75phCLTS1RZ6DphJ5UUZaGOHIHfYHssGHPTu0rCZ12vnOJzkj VJ5Mt9IG28Bn9w5NSRdMJXXBD8um5qj+gZHPKbC10bgfUBJCvWEIxArkOiO2RDPT32k/ rZJx18sosR84PdHF7v3OHSjmMTDb07Ud7Hjw4g3QpWhzbZRpWZQqYoXJpzQvy1AiOkJH 9oqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=xU26eKhAat6ZuGhDgaDU4lA3EkxCkgm/s81rka2sejI=; b=tATLSXcjOfx0zWs7c92BBmT5KedZcKziKeTsYjNBk8dcXl72kFbHjzC+Iz1ax1hlji 2+8/Qu7naBH118HJ+8LXmeE5lYBQd78xzAsAtfwmZ07idvUUTdBLM6RxUmVVSdv1gLNi P7IDTUkUjSV53aIJkQzzxL8l5TZZy+NvrswBb7Kn/rS03FD/KOcGsbjCDe10dSveKnFv lcZ/x1ciLjfLHEHY1j336MkfW/FS4iEPIOZhTtlEAmXkIukQkZ9e0OtwjIIg1Nl+Uais 2g6cASj/ZJLbbZhVAA6wgBVLRmW28EUs8peA9HLDVveurGeyFTJKorHBcRYNwHBXIHfC KJ6g== X-Gm-Message-State: AOAM5307pA7RHRTmvVoZ1ysMN93i4UvTSJP4f1FnjGj/PA7/hWD35fK+ oaDIoP5yqRjwsFUb1YLlOn4PevocCFyaQtybAck= X-Google-Smtp-Source: ABdhPJwBNAOYLNSRfUtYzVTxF2AYiX9nqQGGM+fJ+rtx+rAaaxqanQIebBFJnPrd9GA9ddLcf6+KFh8vSnkc+g05TdA= X-Received: by 2002:a05:6808:2d0:: with SMTP id a16mr12208850oid.116.1619621835014; Wed, 28 Apr 2021 07:57:15 -0700 (PDT) MIME-Version: 1.0 References: <20210427204720.25007-1-yu-cheng.yu@intel.com> <0e03c50ea05440209d620971b9db4f29@AcuMS.aculab.com> In-Reply-To: From: "H.J. Lu" Date: Wed, 28 Apr 2021 07:56:38 -0700 Message-ID: Subject: Re: [PATCH v26 0/9] Control-flow Enforcement: Indirect Branch Tracking To: Andy Lutomirski Cc: David Laight , 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 , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , 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 , Haitao Huang Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Wed, Apr 28, 2021 at 7:52 AM Andy Lutomirski wrote: > > On Wed, Apr 28, 2021 at 7:48 AM David Laight wrote: > > > > From: Yu-cheng Yu > > > Sent: 27 April 2021 21:47 > > > > > > Control-flow Enforcement (CET) is a new Intel processor feature that blocks > > > return/jump-oriented programming attacks. Details are in "Intel 64 and > > > IA-32 Architectures Software Developer's Manual" [1]. > > ... > > > > Does this feature require that 'binary blobs' for out of tree drivers > > be compiled by a version of gcc that adds the ENDBRA instructions? > > > > If enabled for userspace, what happens if an old .so is dynamically > > loaded? CET will be disabled by ld.so in this case. > > Or do all userspace programs and libraries have to have been compiled > > with the ENDBRA instructions? Correct. ld and ld.so check this. > If you believe that the userspace tooling for the legacy IBT table > actually works, then it should just work. Yu-cheng, etc: how well > tested is it? > Legacy IBT bitmap isn't unused since it doesn't cover legacy codes generated by legacy JITs. -- H.J.