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[209.132.180.67]) by mx.google.com with ESMTP id d6-v6si52557632plo.542.2018.06.07.12.10.43; Thu, 07 Jun 2018 12:10:57 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=PMmipzuk; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932345AbeFGSsx (ORCPT + 99 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-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.