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=-0.8 required=3.0 tests=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 7F2F9C433E1 for ; Fri, 22 May 2020 17:18:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4101C20738 for ; Fri, 22 May 2020 17:18:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4101C20738 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C887D80008; Fri, 22 May 2020 13:18:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C3AF780007; Fri, 22 May 2020 13:18:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B4E8580008; Fri, 22 May 2020 13:18:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0004.hostedemail.com [216.40.44.4]) by kanga.kvack.org (Postfix) with ESMTP id 9932D80007 for ; Fri, 22 May 2020 13:18:48 -0400 (EDT) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 648AF5DFE for ; Fri, 22 May 2020 17:18:48 +0000 (UTC) X-FDA: 76845014736.19.slave22_86efa718b0912 X-HE-Tag: slave22_86efa718b0912 X-Filterd-Recvd-Size: 3370 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Fri, 22 May 2020 17:18:47 +0000 (UTC) IronPort-SDR: 0gaLNuBZ4l+VBr8z70y2WgEwOt9SShDdR8C1xY7pldHRuf2St4BFYCmIfYzzY4aPNRgOdwXjBz MHmDrBeAYNlw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 May 2020 10:18:45 -0700 IronPort-SDR: NXUfNJ68BjtyRCcOBPmLk8Z0wQMkH7dKhewmdbuP2bGwLxETp4+qAGhtLYXEmKviVPQKYA5ptO aZJA38nl90ug== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,422,1583222400"; d="scan'208";a="467245771" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by fmsmga005.fm.intel.com with ESMTP; 22 May 2020 10:18:45 -0700 Message-ID: Subject: Re: [PATCH v10 26/26] x86/cet/shstk: Add arch_prctl functions for shadow stack From: Yu-cheng Yu To: Kees Cook Cc: 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 , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang Date: Fri, 22 May 2020 10:17:43 -0700 In-Reply-To: <202005211528.A12B4AD@keescook> References: <20200429220732.31602-1-yu-cheng.yu@intel.com> <20200429220732.31602-27-yu-cheng.yu@intel.com> <202005211528.A12B4AD@keescook> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.32.4 (3.32.4-1.fc30) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 2020-05-21 at 15:42 -0700, Kees Cook wrote: > On Wed, Apr 29, 2020 at 03:07:32PM -0700, Yu-cheng Yu wrote: [...] > > + > > +int prctl_cet(int option, u64 arg2) > > +{ > > + struct cet_status *cet; > > + > > + if (!IS_ENABLED(CONFIG_X86_INTEL_CET)) > > + return -EINVAL; > > Using -EINVAL here means userspace can't tell the difference between an > old kernel and a kernel not built with CONFIG_X86_INTEL_CET. Perhaps > -ENOTSUPP? Looked into this. The kernel and GLIBC are not in sync. So maybe we still use EINVAL here? Yu-cheng In kernel: ---------- #define EOPNOTSUPP 95 #define ENOTSUPP 524 In GLIBC: --------- printf("ENOTSUP=%d\n", ENOTSUP); printf("EOPNOTSUPP=%d\n", EOPNOTSUPP); printf("%s=524\n", strerror(524)); ENOTSUP=95 EOPNOTSUPP=95 Unknown error 524=524