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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47C82C433FE for ; Sat, 22 Jan 2022 06:12:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233429AbiAVGM0 (ORCPT ); Sat, 22 Jan 2022 01:12:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229661AbiAVGM0 (ORCPT ); Sat, 22 Jan 2022 01:12:26 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7CAB4C06173B for ; Fri, 21 Jan 2022 22:12:26 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1C85560C5D for ; Sat, 22 Jan 2022 06:12:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10A23C340E4; Sat, 22 Jan 2022 06:12:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1642831945; bh=UPmbSMh7QphyG3WMf24B9AsIcfJqmYQrWbAqNXon6f4=; h=Date:From:To:Subject:In-Reply-To:From; b=k04CIHSp4U0tSHL75astEEyTION0Jn1aK7rx+L1fHzDIen/VpPf9oz57BJVHWk/Ey gxhUCU41UE0sVN6jNjUBdEy6IdaOTsvInLTjj41JUTDwNDWe9Zqg/fOL7HY+JgS96M DXbYEk11WWNzD0RvEiGZsdqxWOq9u0vYDPq7WNbY= Date: Fri, 21 Jan 2022 22:12:23 -0800 From: Andrew Morton To: airlied@linux.ie, akpm@linux-foundation.org, amir73il@gmail.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bcrl@kvack.org, benh@kernel.crashing.org, clemens@ladisch.de, crope@iki.fi, dgilbert@interlog.com, ebiederm@xmission.com, gregkh@linuxfoundation.org, jack@suse.cz, jani.nikula@intel.com, jani.nikula@linux.intel.com, jejb@linux.ibm.com, jlbec@evilplan.org, john.ogness@linutronix.de, joonas.lahtinen@linux.intel.com, joseph.qi@linux.alibaba.com, julia.lawall@inria.fr, keescook@chromium.org, kernel@tuxforce.de, linux-mm@kvack.org, mark@fasheh.com, martin.petersen@oracle.com, mcgrof@kernel.org, mm-commits@vger.kernel.org, nixiaoming@huawei.com, penguin-kernel@I-love.SAKURA.ne.jp, peterz@infradead.org, phil@philpotter.co.uk, pjt@google.com, pmladek@suse.com, rafael@kernel.org, rodrigo.vivi@intel.com, rostedt@goodmis.org, senozhatsky@chromium.org, sre@kernel.org, steve@sk2.org, surenb@google.com, torvalds@linux-foundation.org, tytso@mit.edu, viro@zeniv.linux.org.uk, wangqing@vivo.com, yzaikin@google.com Subject: [patch 21/69] sysctl: add helper to register a sysctl mount point Message-ID: <20220122061223.m4kWDxt5y%akpm@linux-foundation.org> In-Reply-To: <20220121221021.60533b009c357d660791476e@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Luis Chamberlain Subject: sysctl: add helper to register a sysctl mount point The way to create a subdirectory on top of sysctl_mount_point is a bit obscure, and *why* we do that even so more. Provide a helper which makes it clear why we do this. [akpm@linux-foundation.org: export register_sysctl_mount_point() to modules] Link: https://lkml.kernel.org/r/20211124231435.1445213-4-mcgrof@kernel.org Signed-off-by: Luis Chamberlain Suggested-by: "Eric W. Biederman" Cc: Al Viro Cc: Amir Goldstein Cc: Andy Shevchenko Cc: Antti Palosaari Cc: Arnd Bergmann Cc: Benjamin Herrenschmidt Cc: Benjamin LaHaise Cc: Clemens Ladisch Cc: David Airlie Cc: Douglas Gilbert Cc: Greg Kroah-Hartman Cc: Iurii Zaikin Cc: James E.J. Bottomley Cc: Jani Nikula Cc: Jani Nikula Cc: Jan Kara Cc: Joel Becker Cc: John Ogness Cc: Joonas Lahtinen Cc: Joseph Qi Cc: Julia Lawall Cc: Kees Cook Cc: Lukas Middendorf Cc: Mark Fasheh Cc: Martin K. Petersen Cc: Paul Turner Cc: Peter Zijlstra Cc: Petr Mladek Cc: Phillip Potter Cc: Qing Wang Cc: "Rafael J. Wysocki" Cc: Rodrigo Vivi Cc: Sebastian Reichel Cc: Sergey Senozhatsky Cc: Stephen Kitt Cc: Steven Rostedt (VMware) Cc: Suren Baghdasaryan Cc: Tetsuo Handa Cc: "Theodore Ts'o" Cc: Xiaoming Ni Signed-off-by: Andrew Morton --- fs/proc/proc_sysctl.c | 14 ++++++++++++++ include/linux/sysctl.h | 7 +++++++ 2 files changed, 21 insertions(+) --- a/fs/proc/proc_sysctl.c~sysctl-add-helper-to-register-a-sysctl-mount-point +++ a/fs/proc/proc_sysctl.c @@ -35,6 +35,20 @@ struct ctl_table sysctl_mount_point[] = { } }; +/** + * register_sysctl_mount_point() - registers a sysctl mount point + * @path: path for the mount point + * + * Used to create a permanently empty directory to serve as mount point. + * There are some subtle but important permission checks this allows in the + * case of unprivileged mounts. + */ +struct ctl_table_header *register_sysctl_mount_point(const char *path) +{ + return register_sysctl(path, sysctl_mount_point); +} +EXPORT_SYMBOL(register_sysctl_mount_point); + static bool is_empty_dir(struct ctl_table_header *head) { return head->ctl_table[0].child == sysctl_mount_point; --- a/include/linux/sysctl.h~sysctl-add-helper-to-register-a-sysctl-mount-point +++ a/include/linux/sysctl.h @@ -209,6 +209,8 @@ extern int sysctl_init(void); extern void __register_sysctl_init(const char *path, struct ctl_table *table, const char *table_name); #define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table) +extern struct ctl_table_header *register_sysctl_mount_point(const char *path); + void do_sysctl_args(void); extern int pwrsw_enabled; @@ -223,6 +225,11 @@ static inline struct ctl_table_header *r { return NULL; } + +static inline struct sysctl_header *register_sysctl_mount_point(const char *path) +{ + return NULL; +} static inline struct ctl_table_header *register_sysctl_paths( const struct ctl_path *path, struct ctl_table *table) _