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=-13.7 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 4D1B0C4332B for ; Fri, 12 Mar 2021 16:43:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B91A65040 for ; Fri, 12 Mar 2021 16:43:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232109AbhCLQml (ORCPT ); Fri, 12 Mar 2021 11:42:41 -0500 Received: from raptor.unsafe.ru ([5.9.43.93]:49778 "EHLO raptor.unsafe.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232942AbhCLQmE (ORCPT ); Fri, 12 Mar 2021 11:42:04 -0500 Received: from comp-core-i7-2640m-0182e6.redhat.com (ip-94-113-225-162.net.upcbroadband.cz [94.113.225.162]) by raptor.unsafe.ru (Postfix) with ESMTPSA id D512740C9A; Fri, 12 Mar 2021 16:42:01 +0000 (UTC) From: Alexey Gladkov To: LKML , "Eric W . Biederman" Cc: Alexey Gladkov , Alexander Viro , Kees Cook , Linux Containers , Linux FS Devel Subject: [PATCH v6 1/5] docs: proc: add documentation about mount restrictions Date: Fri, 12 Mar 2021 17:41:44 +0100 Message-Id: X-Mailer: git-send-email 2.29.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.6.4 (raptor.unsafe.ru [0.0.0.0]); Fri, 12 Mar 2021 16:42:02 +0000 (UTC) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Signed-off-by: Alexey Gladkov --- Documentation/filesystems/proc.rst | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 2fa69f710e2a..5a1bb0e081fd 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -50,6 +50,7 @@ fixes/update part 1.1 Stefani Seibold June 9 2009 4 Configuring procfs 4.1 Mount options + 4.2 Mount restrictions 5 Filesystem behavior @@ -2175,6 +2176,19 @@ information about processes information, just add identd to this group. subset=pid hides all top level files and directories in the procfs that are not related to tasks. +4.2 Mount restrictions +-------------------------- + +If user namespaces are in use, the kernel additionally checks the instances of +procfs available to the mounter and will not allow procfs to be mounted if: + + 1. This mount is not fully visible. + + a. It's root directory is not the root directory of the filesystem. + b. If any file or non-empty procfs directory is hidden by another mount. + + 2. A new mount overrides the readonly option or any option from atime familty. + Chapter 5: Filesystem behavior ============================== -- 2.29.3