linux-kernel - Re: A syscall for changing birth time

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250310221243.0d5db7b3@pumpkin>
Date: Mon, 10 Mar 2025 22:12:43 +0000
From: David Laight <david.laight.linux@...il.com>
To: "Theodore Ts'o" <tytso@....edu>
Cc: "Artem S. Tashkinov" <aros@....com>, linux-ext4@...r.kernel.org, Linux
 Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: A syscall for changing birth time

On Mon, 10 Mar 2025 09:58:28 -0400
"Theodore Ts'o" <tytso@....edu> wrote:

> On Mon, Mar 10, 2025 at 07:26:00AM +0000, Artem S. Tashkinov wrote:
> > 
> > Why is it that the Linux kernel supports reading btime, but there's no
> > syscall to change it? At least for ext4 there's the debugfs utility, but
> > for other filesystems there's just nothing. And even debugfs is not a
> > solution, since it requires root privileges and an unmounted/mounted RO
> > filesystem.  
> 
> POSIX and Single Unix Specification also doesn't provide a way to
> allow userspace to set ctime (inode change time).  That's because the
> definition of "change time" is defined to include the time to change
> anything about the inode metadata --- including the inode timestamps.
> 

I'm sure that hadn't used to be the case.
But as some point the 'ctime' changed from something that was usually
the file create time (for some definition of create) to a pretty useless
time that is almost a waste of disk space.

	David