From patchwork Thu Mar 11 10:52:41 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: 12130921 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 E7A5AC433DB for ; Thu, 11 Mar 2021 10:53:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6B7564EFD for ; Thu, 11 Mar 2021 10:53:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232474AbhCKKxV (ORCPT ); Thu, 11 Mar 2021 05:53:21 -0500 Received: from smtp-190a.mail.infomaniak.ch ([185.125.25.10]:34991 "EHLO smtp-190a.mail.infomaniak.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232479AbhCKKwy (ORCPT ); Thu, 11 Mar 2021 05:52:54 -0500 Received: from smtp-2-0000.mail.infomaniak.ch (unknown [10.5.36.107]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4Dx5Px0mNmzMqP1b; Thu, 11 Mar 2021 11:52:53 +0100 (CET) Received: from localhost (unknown [23.97.221.149]) by smtp-2-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4Dx5Pw48Nszlh8tv; Thu, 11 Mar 2021 11:52:52 +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" , 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 v3 0/1] Unprivileged chroot Date: Thu, 11 Mar 2021 11:52:41 +0100 Message-Id: <20210311105242.874506-1-mic@digikod.net> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi, This new patch replaces the path_is_under() check with current_chrooted() as it is done with user namespaces. Indeed, it is much more simple to check the current root instead of limiting access to a subset of files. 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-rc2 . I would really appreciate constructive reviews. Previous version: https://lore.kernel.org/r/20210310181857.401675-1-mic@digikod.net Regards, Mickaël Salaün (1): fs: Allow no_new_privs tasks to call chroot(2) fs/open.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) base-commit: a38fd8748464831584a19438cbb3082b5a2dab15