From: Askar Safin <safinaskar@zohomail.com>
To: "Aleksa Sarai" <cyphar@cyphar.com>
Cc: "Alejandro Colomar" <alx@kernel.org>,
"Michael T. Kerrisk" <mtk.manpages@gmail.com>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Jan Kara" <jack@suse.cz>,
"G. Branden Robinson" <g.branden.robinson@gmail.com>,
"linux-man" <linux-man@vger.kernel.org>,
"linux-api" <linux-api@vger.kernel.org>,
"linux-fsdevel" <linux-fsdevel@vger.kernel.org>,
"linux-kernel" <linux-kernel@vger.kernel.org>,
"David Howells" <dhowells@redhat.com>,
"Christian Brauner" <brauner@kernel.org>
Subject: Re: [PATCH v3 06/12] man/man2/fsconfig.2: document "new" mount API
Date: Thu, 21 Aug 2025 14:25:35 +0400 [thread overview]
Message-ID: <198cc299cd9.eec1817f85794.4679093070969175955@zohomail.com> (raw)
In-Reply-To: <20250809-new-mount-api-v3-6-f61405c80f34@cyphar.com>
There is a convention: you can pass invalid fd (such as -1) as dfd to *at-syscalls to enforce that the path is absolute.
This is documented. "man openat" says: "Specifying an invalid file descriptor number in dirfd can be used as a means to ensure that pathname is absolute".
But fsconfig with FSCONFIG_SET_PATH breaks this convention due to this line: https://elixir.bootlin.com/linux/v6.16/source/fs/fsopen.c#L377 .
I think this is a bug, and it should be fixed in kernel. Also, it is possible there are a lot of similarly buggy syscalls. All of them should be fixed,
and moreover a warning should be added to https://docs.kernel.org/process/adding-syscalls.html . And then new fsconfig behavior should be documented.
(Of course, I'm not saying that *you* should do all these. I'm just saying that this bug exists.) (I tested this.)
--
Askar Safin
https://types.pl/@safinaskar
next prev parent reply other threads:[~2025-08-21 10:26 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-08 20:39 [PATCH v3 00/12] man2: document "new" mount API Aleksa Sarai
2025-08-08 20:39 ` [PATCH v3 01/12] man/man2/statx.2: correctly document AT_NO_AUTOMOUNT Aleksa Sarai
2025-08-08 20:39 ` [PATCH v3 02/12] man/man2/mount_setattr.2: fix stray quote in SYNOPSIS Aleksa Sarai
2025-08-08 20:39 ` [PATCH v3 03/12] man/man2/mount_setattr.2: move mount_attr struct to mount_attr(2type) Aleksa Sarai
2025-08-08 20:39 ` [PATCH v3 04/12] man/man2/fsopen.2: document "new" mount API Aleksa Sarai
2025-08-08 20:39 ` [PATCH v3 05/12] man/man2/fspick.2: " Aleksa Sarai
2025-08-22 13:23 ` Askar Safin
2025-08-22 13:40 ` Aleksa Sarai
2025-08-25 16:22 ` Askar Safin
2025-08-08 20:39 ` [PATCH v3 06/12] man/man2/fsconfig.2: " Aleksa Sarai
2025-08-12 18:25 ` Aleksa Sarai
2025-08-21 9:42 ` Askar Safin
2025-08-21 11:44 ` Aleksa Sarai
2025-08-21 11:57 ` Askar Safin
2025-08-21 10:25 ` Askar Safin [this message]
2025-08-21 11:47 ` Aleksa Sarai
2025-08-08 20:39 ` [PATCH v3 07/12] man/man2/fsmount.2: " Aleksa Sarai
2025-08-12 9:16 ` Askar Safin
2025-08-12 14:33 ` Aleksa Sarai
2025-08-12 16:18 ` Aleksa Sarai
2025-08-20 9:55 ` Askar Safin
2025-08-20 10:38 ` Aleksa Sarai
2025-08-20 11:53 ` Askar Safin
2025-08-08 20:39 ` [PATCH v3 08/12] man/man2/move_mount.2: " Aleksa Sarai
2025-08-12 10:00 ` Askar Safin
2025-08-12 14:36 ` Aleksa Sarai
2025-08-20 11:18 ` Askar Safin
2025-08-08 20:39 ` [PATCH v3 09/12] man/man2/open_tree.2: " Aleksa Sarai
2025-08-21 11:27 ` Askar Safin
2025-08-21 11:33 ` Christian Brauner
2025-08-24 6:53 ` Askar Safin
2025-08-08 20:39 ` [PATCH v3 10/12] man/man2/mount_setattr.2: mirror opening sentence from fsopen(2) Aleksa Sarai
2025-08-08 20:39 ` [PATCH v3 11/12] man/man2/open_tree{,_attr}.2: document new open_tree_attr() API Aleksa Sarai
2025-08-08 20:39 ` [PATCH v3 12/12] man/man2/{fsconfig,mount_setattr}.2: add note about attribute-parameter distinction Aleksa Sarai
2025-08-09 15:04 ` [PATCH v3 00/12] man2: document "new" mount API Askar Safin
2025-08-09 15:11 ` Alejandro Colomar
2025-08-09 17:32 ` Aleksa Sarai
2025-08-11 11:27 ` Alejandro Colomar
2025-08-17 7:52 ` Askar Safin
2025-08-17 16:16 ` Aleksa Sarai
2025-08-17 18:50 ` Askar Safin
2025-08-18 5:46 ` Aleksa Sarai
2025-08-19 8:31 ` Christian Brauner
2025-08-19 8:50 ` Aleksa Sarai
2025-08-20 11:37 ` Askar Safin
2025-08-21 11:49 ` Aleksa Sarai
2025-08-21 12:14 ` Askar Safin
2025-08-21 14:21 ` Aleksa Sarai
2025-08-24 13:07 ` Askar Safin
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