From patchwork Tue Mar 16 20:36:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= X-Patchwork-Id: 12143855 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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT 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 389DFC4332B for ; Tue, 16 Mar 2021 20:37:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1135764F9E for ; Tue, 16 Mar 2021 20:37:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231382AbhCPUgu (ORCPT ); Tue, 16 Mar 2021 16:36:50 -0400 Received: from smtp-42ab.mail.infomaniak.ch ([84.16.66.171]:48931 "EHLO smtp-42ab.mail.infomaniak.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231391AbhCPUgl (ORCPT ); Tue, 16 Mar 2021 16:36:41 -0400 Received: from smtp-2-0000.mail.infomaniak.ch (unknown [10.5.36.107]) by smtp-2-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4F0Q786zFXzMqHss; Tue, 16 Mar 2021 21:36:36 +0100 (CET) Received: from localhost (unknown [23.97.221.149]) by smtp-2-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4F0Q750v9wzlppyk; Tue, 16 Mar 2021 21:36:32 +0100 (CET) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: Al Viro , James Morris , Serge Hallyn Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Andy Lutomirski , Casey Schaufler , Christian Brauner , Christoph Hellwig , David Howells , Dominik Brodowski , "Eric W . Biederman" , Jann Horn , John Johansen , Kees Cook , Kentaro Takeda , Tetsuo Handa , kernel-hardening@lists.openwall.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v5 0/1] Unprivileged chroot Date: Tue, 16 Mar 2021 21:36:32 +0100 Message-Id: <20210316203633.424794-1-mic@digikod.net> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Precedence: bulk List-ID: Hi, This new patch fix a race (spotted by Jann Horn) when reading current->fs->users . The chroot system call is currently limited to be used by processes with the CAP_SYS_CHROOT capability. This protects against malicious procesess willing to trick SUID-like binaries. The following patch allows unprivileged users to safely use chroot(2), which may be complementary to the use of user namespaces. This patch is a follow-up of a previous one sent by Andy Lutomirski some time ago: https://lore.kernel.org/lkml/0e2f0f54e19bff53a3739ecfddb4ffa9a6dbde4d.1327858005.git.luto@amacapital.net/ This patch can be applied on top of v5.12-rc3 . I would really appreciate constructive reviews. Previous versions: v4: https://lore.kernel.org/r/20210316170135.226381-1-mic@digikod.net v3: https://lore.kernel.org/r/20210311105242.874506-1-mic@digikod.net v2: https://lore.kernel.org/r/20210310181857.401675-1-mic@digikod.net v1: https://lore.kernel.org/r/20210310161000.382796-1-mic@digikod.net Regards, Mickaël Salaün (1): fs: Allow no_new_privs tasks to call chroot(2) fs/open.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) base-commit: 1e28eed17697bcf343c6743f0028cc3b5dd88bf0