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From: Askar Safin <safinaskar@gmail.com>
To: cyphar@cyphar.com
Cc: alx@kernel.org, brauner@kernel.org, dhowells@redhat.com,
	g.branden.robinson@gmail.com, jack@suse.cz,
	linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-man@vger.kernel.org,
	mtk.manpages@gmail.com, safinaskar@zohomail.com,
	viro@zeniv.linux.org.uk
Subject: Re: [PATCH v4 03/10] man/man2/fspick.2: document "new" mount API
Date: Mon, 22 Sep 2025 03:25:29 +0300	[thread overview]
Message-ID: <20250922002529.95574-1-safinaskar@gmail.com> (raw)
In-Reply-To: <20250919-new-mount-api-v4-3-1261201ab562@cyphar.com>

> With the notable caveat that in this example, mount(2) will clear all other filesystem parameters (such as MS_NOSUID or MS_NOEXEC); fsconfig(2) will only modify the ro parameter.

MS_NOSUID and MS_NOEXEC are not filesystem parameters. They can be set per-mount, but not
per-filesystem. Here is list of all filesystem-agnostic per-superblock parameters:

https://elixir.bootlin.com/linux/v6.17-rc6/source/fs/namespace.c#L4103

Note that these SB_* constants are equal to corresponding MS_* constants.

As you can see, there is no NOSUID and NOEXEC in that list.

Also, SB_NOSUID does exist:
https://elixir.bootlin.com/linux/v6.17-rc6/source/include/linux/fs.h#L1240
.

So, it seems that "NOSUID superblock" does exist as a concept. But, thanks to
code in path_mount (provided above) user cannot (in filesystem-agnostic way)
make given superblock NOSUID.

So, from user point of view, NOSUID and NOEXEC are not filesystem parameters.

If you need some example of filesystem parameter, I suggest MS_SYNCHRONOUS,
I used it here:
https://lore.kernel.org/all/198d1f2e189.11dbac16b2998.3847935512688537521@zohomail.com/

-- 
Askar Safin

  parent reply	other threads:[~2025-09-22  0:25 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-19  1:59 [PATCH v4 00/10] man2: document "new" mount API Aleksa Sarai
2025-09-19  1:59 ` [PATCH v4 01/10] man/man2/mount_setattr.2: move mount_attr struct to mount_attr(2type) Aleksa Sarai
2025-09-19 16:04   ` Alejandro Colomar
2025-09-19  1:59 ` [PATCH v4 02/10] man/man2/fsopen.2: document "new" mount API Aleksa Sarai
2025-09-19 16:24   ` Alejandro Colomar
2025-09-19 21:19     ` Aleksa Sarai
2025-09-21  1:33       ` Aleksa Sarai
2025-09-21  8:39         ` Alejandro Colomar
2025-09-19  1:59 ` [PATCH v4 03/10] man/man2/fspick.2: " Aleksa Sarai
2025-09-21  8:53   ` Alejandro Colomar
2025-09-21 14:55     ` Aleksa Sarai
2025-09-21 15:17       ` Alejandro Colomar
2025-09-22  0:25   ` Askar Safin [this message]
2025-09-19  1:59 ` [PATCH v4 04/10] man/man2/fsconfig.2: " Aleksa Sarai
2025-09-21  9:26   ` Alejandro Colomar
2025-09-24  6:41     ` Aleksa Sarai
2025-09-24  8:52       ` Alejandro Colomar
2025-09-19  1:59 ` [PATCH v4 05/10] man/man2/fsmount.2: " Aleksa Sarai
2025-09-21 23:08   ` Askar Safin
2025-09-22  1:10     ` Askar Safin
2025-09-19  1:59 ` [PATCH v4 06/10] man/man2/move_mount.2: " Aleksa Sarai
2025-09-19  1:59 ` [PATCH v4 07/10] man/man2/open_tree.2: " Aleksa Sarai
2025-09-21  9:47   ` Alejandro Colomar
2025-09-22 10:09     ` Aleksa Sarai
2025-09-22 13:22       ` Alejandro Colomar
2025-09-24  1:34         ` Aleksa Sarai
2025-09-19  1:59 ` [PATCH v4 08/10] man/man2/mount_setattr.2: mirror opening sentence from fsopen(2) Aleksa Sarai
2025-09-21  9:50   ` Alejandro Colomar
2025-09-21 10:03     ` Aleksa Sarai
2025-09-21 10:19       ` Alejandro Colomar
2025-09-19  1:59 ` [PATCH v4 09/10] man/man2/open_tree{,_attr}.2: document new open_tree_attr() API Aleksa Sarai
2025-09-21  9:55   ` Alejandro Colomar
2025-09-24  6:31     ` Aleksa Sarai
2025-09-24  8:51       ` Alejandro Colomar
2025-09-19  1:59 ` [PATCH v4 10/10] man/man2/{fsconfig,mount_setattr}.2: add note about attribute-parameter distinction Aleksa Sarai
2025-09-19 12:23   ` Aleksa Sarai
2025-09-21  9:59   ` Alejandro Colomar
2025-09-22  1:06   ` Askar Safin
2025-09-21  2:43 ` [PATCH v4 00/10] man2: document "new" mount API Askar Safin
2025-09-21  9:58   ` Aleksa Sarai
2025-09-24 11:11     ` Aleksa Sarai

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