From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id Nsb3ARh+GVtyXwAAmS7hNA ; Thu, 07 Jun 2018 18:48:56 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id DE5FA6074D; Thu, 7 Jun 2018 18:48:55 +0000 (UTC) Authentication-Results: smtp.codeaurora.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="PMmipzuk" X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,T_DKIMWL_WL_HIGH autolearn=unavailable autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 75E8C606DD; Thu, 7 Jun 2018 18:48:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 75E8C606DD Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932357AbeFGSsx (ORCPT + 25 others); Thu, 7 Jun 2018 14:48:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:36430 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932295AbeFGSsu (ORCPT ); Thu, 7 Jun 2018 14:48:50 -0400 Received: from mail-wr0-f174.google.com (mail-wr0-f174.google.com [209.85.128.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 65E91208A1 for ; Thu, 7 Jun 2018 18:48:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1528397329; bh=HfInhCyX/FTxEMsMJGmwxfuf7NZf4eBRhMw3s/6QFxA=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=PMmipzukHGtQ8CmyBx0yvgnS7RJ9un9zdoQFFcXBmd2DcvroUtNRXmKaLHV5B9k1q 61fe2IgbZwOYHuTRIpRtY0X2vgGYmrl4qExtGVm9hsMoQrN3wTm0ZN4P2X4+ic1DvJ aHwcC3VDnS1i7Z4Ejuj/iRHBgxYpGVD3iSfC0Lpc= Received: by mail-wr0-f174.google.com with SMTP id o12-v6so10854876wrm.12 for ; Thu, 07 Jun 2018 11:48:49 -0700 (PDT) X-Gm-Message-State: APt69E07q3Daa/P64pPHO6yvNUJC8g7kWPwyG0g6RBmDw9tnTS/k9F4Z +QF10wk1RLz2CLbTP7Db7Hu1H3mYz9vgUCDPdpwXzA== X-Google-Smtp-Source: ADUXVKIPTs1I8dvveoP0fR8ZOInjWi2OXekZcMP/Ic3PqS81cZZcEViIYLFVCicMbBcJKzAJwM0DvuEmSR22DP+gGwY= X-Received: by 2002:adf:b445:: with SMTP id v5-v6mr2547603wrd.67.1528397327870; Thu, 07 Jun 2018 11:48:47 -0700 (PDT) MIME-Version: 1.0 References: <20180607143807.3611-1-yu-cheng.yu@intel.com> <20180607143807.3611-7-yu-cheng.yu@intel.com> In-Reply-To: <20180607143807.3611-7-yu-cheng.yu@intel.com> From: Andy Lutomirski Date: Thu, 7 Jun 2018 11:48:35 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 06/10] x86/cet: Add arch_prctl functions for shadow stack To: Yu-cheng Yu Cc: LKML , linux-doc@vger.kernel.org, Linux-MM , linux-arch , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "H. J. Lu" , "Shanbhogue, Vedvyas" , "Ravi V. Shankar" , Dave Hansen , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , mike.kravetz@oracle.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 7, 2018 at 7:41 AM Yu-cheng Yu wrote: > > The following operations are provided. > > ARCH_CET_STATUS: > return the current CET status > > ARCH_CET_DISABLE: > disable CET features > > ARCH_CET_LOCK: > lock out CET features > > ARCH_CET_EXEC: > set CET features for exec() > > ARCH_CET_ALLOC_SHSTK: > allocate a new shadow stack > > ARCH_CET_PUSH_SHSTK: > put a return address on shadow stack > > ARCH_CET_ALLOC_SHSTK and ARCH_CET_PUSH_SHSTK are intended only for > the implementation of GLIBC ucontext related APIs. Please document exactly what these all do and why. I don't understand what purpose ARCH_CET_LOCK and ARCH_CET_EXEC serve. CET is opt in for each ELF program, so I think there should be no need for a magic override.