From patchwork Mon Feb 21 21:25:22 2022 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: 12754159 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6BCF6C43217 for ; Mon, 21 Feb 2022 21:23:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234803AbiBUVXY (ORCPT ); Mon, 21 Feb 2022 16:23:24 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:60228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234766AbiBUVXR (ORCPT ); Mon, 21 Feb 2022 16:23:17 -0500 Received: from smtp-bc0d.mail.infomaniak.ch (smtp-bc0d.mail.infomaniak.ch [IPv6:2001:1600:3:17::bc0d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B1E412706 for ; Mon, 21 Feb 2022 13:22:51 -0800 (PST) Received: from smtp-3-0000.mail.infomaniak.ch (unknown [10.4.36.107]) by smtp-2-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4K2Znx4FH4zMqHRq; Mon, 21 Feb 2022 22:15:17 +0100 (CET) Received: from localhost (unknown [23.97.221.149]) by smtp-3-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4K2Znx2S0HzljTgH; Mon, 21 Feb 2022 22:15:17 +0100 (CET) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: James Morris , "Serge E . Hallyn" Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Al Viro , Jann Horn , Kees Cook , Konstantin Meskhidze , Paul Moore , Shuah Khan , linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= Subject: [PATCH v1 11/11] landlock: Add design choices documentation for filesystem access rights Date: Mon, 21 Feb 2022 22:25:22 +0100 Message-Id: <20220221212522.320243-12-mic@digikod.net> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221212522.320243-1-mic@digikod.net> References: <20220221212522.320243-1-mic@digikod.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Mickaël Salaün Signed-off-by: Mickaël Salaün Link: https://lore.kernel.org/r/20220221212522.320243-12-mic@digikod.net Reviewed-by: Paul Moore --- Documentation/security/landlock.rst | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/Documentation/security/landlock.rst b/Documentation/security/landlock.rst index 3df68cb1d10f..621b2c1ac514 100644 --- a/Documentation/security/landlock.rst +++ b/Documentation/security/landlock.rst @@ -7,7 +7,7 @@ Landlock LSM: kernel documentation ================================== :Author: Mickaël Salaün -:Date: March 2021 +:Date: February 2022 Landlock's goal is to create scoped access-control (i.e. sandboxing). To harden a whole system, this feature should be available to any process, @@ -42,6 +42,21 @@ Guiding principles for safe access controls * Computation related to Landlock operations (e.g. enforcing a ruleset) shall only impact the processes requesting them. +Design choices +============== + +Filesystem access rights +------------------------ + +All access rights are tied to an inode and what can be accessed through it. +Reading the content of a directory doesn't imply to be allowed to read the +content of a listed inode. Indeed, a file name is local to its parent +directory, and an inode can be referenced by multiple file names thanks to +(hard) links. Being able to unlink a file only has a direct impact on the +directory, not the unlinked inode. This is the reason why +`LANDLOCK_ACCESS_FS_REMOVE_FILE` or `LANDLOCK_ACCESS_FS_REFER` are not allowed +to be tied to files but only to directories. + Tests =====