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=-5.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 9B093C38A2A for ; Thu, 7 May 2020 08:36:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 83EFA2078C for ; Thu, 7 May 2020 08:36:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726538AbgEGIgs (ORCPT ); Thu, 7 May 2020 04:36:48 -0400 Received: from smtp-bc0d.mail.infomaniak.ch ([45.157.188.13]:60499 "EHLO smtp-bc0d.mail.infomaniak.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725903AbgEGIgq (ORCPT ); Thu, 7 May 2020 04:36:46 -0400 Received: from smtp-2-0001.mail.infomaniak.ch (unknown [10.5.36.108]) by smtp-2-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 49Hmyz5P4szlhrLP; Thu, 7 May 2020 10:36:43 +0200 (CEST) Received: from ns3096276.ip-94-23-54.eu (unknown [94.23.54.103]) by smtp-2-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 49Hmyx5yyJzlrBJt; Thu, 7 May 2020 10:36:41 +0200 (CEST) Subject: Re: [PATCH v5 0/6] Add support for O_MAYEXEC To: David Laight , "linux-kernel@vger.kernel.org" Cc: Aleksa Sarai , Alexei Starovoitov , Al Viro , Andy Lutomirski , Christian Heimes , Daniel Borkmann , Deven Bowers , Eric Chiang , Florian Weimer , James Morris , Jan Kara , Jann Horn , Jonathan Corbet , Kees Cook , Lakshmi Ramasubramanian , Matthew Garrett , Matthew Wilcox , Michael Kerrisk , =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= , Mimi Zohar , =?UTF-8?Q?Philippe_Tr=c3=a9buchet?= , Scott Shell , Sean Christopherson , Shuah Khan , Steve Dower , Steve Grubb , Thibaut Sautereau , Vincent Strubel , "kernel-hardening@lists.openwall.com" , "linux-api@vger.kernel.org" , "linux-integrity@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" References: <20200505153156.925111-1-mic@digikod.net> <20b24b9ca0a64afb9389722845738ec8@AcuMS.aculab.com> From: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= Message-ID: <907109c8-9b19-528a-726f-92c3f61c1563@digikod.net> Date: Thu, 7 May 2020 10:36:41 +0200 User-Agent: MIME-Version: 1.0 In-Reply-To: <20b24b9ca0a64afb9389722845738ec8@AcuMS.aculab.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Antivirus: Dr.Web (R) for Unix mail servers drweb plugin ver.6.0.2.8 X-Antivirus-Code: 0x100000 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/05/2020 10:05, David Laight wrote: > From: Mickaël Salaün >> Sent: 05 May 2020 16:32 >> >> This fifth patch series add new kernel configurations (OMAYEXEC_STATIC, >> OMAYEXEC_ENFORCE_MOUNT, and OMAYEXEC_ENFORCE_FILE) to enable to >> configure the security policy at kernel build time. As requested by >> Mimi Zohar, I completed the series with one of her patches for IMA. >> >> The goal of this patch series is to enable to control script execution >> with interpreters help. A new O_MAYEXEC flag, usable through >> openat2(2), is added to enable userspace script interpreter to delegate >> to the kernel (and thus the system security policy) the permission to >> interpret/execute scripts or other files containing what can be seen as >> commands. >> >> A simple system-wide security policy can be enforced by the system >> administrator through a sysctl configuration consistent with the mount >> points or the file access rights. The documentation patch explains the >> prerequisites. >> >> Furthermore, the security policy can also be delegated to an LSM, either >> a MAC system or an integrity system. For instance, the new kernel >> MAY_OPENEXEC flag closes a major IMA measurement/appraisal interpreter >> integrity gap by bringing the ability to check the use of scripts [1]. >> Other uses are expected, such as for openat2(2) [2], SGX integration >> [3], bpffs [4] or IPE [5]. >> >> Userspace needs to adapt to take advantage of this new feature. For >> example, the PEP 578 [6] (Runtime Audit Hooks) enables Python 3.8 to be >> extended with policy enforcement points related to code interpretation, >> which can be used to align with the PowerShell audit features. >> Additional Python security improvements (e.g. a limited interpreter >> withou -c, stdin piping of code) are on their way. >> >> The initial idea come from CLIP OS 4 and the original implementation has >> been used for more than 12 years: >> https://github.com/clipos-archive/clipos4_doc >> >> An introduction to O_MAYEXEC was given at the Linux Security Summit >> Europe 2018 - Linux Kernel Security Contributions by ANSSI: >> https://www.youtube.com/watch?v=chNjCRtPKQY&t=17m15s >> The "write xor execute" principle was explained at Kernel Recipes 2018 - >> CLIP OS: a defense-in-depth OS: >> https://www.youtube.com/watch?v=PjRE0uBtkHU&t=11m14s >> >> This patch series can be applied on top of v5.7-rc4. This can be tested >> with CONFIG_SYSCTL. I would really appreciate constructive comments on >> this patch series. > > None of that description actually says what the patch actually does. "Add support for O_MAYEXEC" "to enable to control script execution". What is not clear here? This seems well understood by other commenters. The documentation patch and the talks can also help.