From: Al Viro <viro@zeniv.linux.org.uk>
To: Askar Safin <safinaskar@gmail.com>
Cc: christian@brauner.io, hpa@zytor.com, jack@suse.cz,
linux-fsdevel@vger.kernel.org, torvalds@linux-foundation.org,
werner@almesberger.net, Aleksa Sarai <cyphar@cyphar.com>
Subject: Re: [RFC] pivot_root(2) races
Date: Fri, 13 Feb 2026 22:28:57 +0000 [thread overview]
Message-ID: <20260213222857.GR3183987@ZenIV> (raw)
In-Reply-To: <20260213173427.112803-1-safinaskar@gmail.com>
On Fri, Feb 13, 2026 at 08:34:27PM +0300, Askar Safin wrote:
> Al Viro <viro@zeniv.linux.org.uk>:
> > We could restrict the set of those who could be flipped, but I doubt
> > that "could ptrace" is workable - that would exclude all kernel threads,
> > and that could easily break existing setups in hard-to-recover ways.
>
> No. Kernel threads share cwd and root with init, because we create PID 1
> with CLONE_FS:
>
> https://elixir.bootlin.com/linux/v6.19-rc5/source/init/main.c#L722
knfsd does not. There's an explicit "give me a separate fs_struct" since
it want ->umask to be independent.
next prev parent reply other threads:[~2026-02-13 22:26 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-09 0:34 [RFC] pivot_root(2) races Al Viro
2026-02-09 5:49 ` Linus Torvalds
2026-02-09 5:53 ` H. Peter Anvin
2026-02-09 6:34 ` Al Viro
2026-02-09 6:44 ` Linus Torvalds
2026-02-09 11:53 ` Christian Brauner
2026-02-12 17:17 ` Askar Safin
2026-02-12 19:11 ` Linus Torvalds
2026-02-12 19:31 ` H. Peter Anvin
2026-02-13 9:51 ` Aleksa Sarai
2026-02-13 17:47 ` Askar Safin
2026-02-13 20:27 ` H. Peter Anvin
2026-02-13 20:35 ` H. Peter Anvin
2026-02-13 22:25 ` Al Viro
2026-02-13 23:00 ` H. Peter Anvin
2026-02-13 23:41 ` Al Viro
2026-02-13 23:40 ` H. Peter Anvin
2026-02-14 12:42 ` Christian Brauner
2026-02-15 0:48 ` H. Peter Anvin
2026-02-17 8:37 ` Christian Brauner
2026-02-14 16:20 ` Askar Safin
2026-02-15 0:49 ` H. Peter Anvin
2026-02-13 13:46 ` Aleksa Sarai
2026-02-13 15:03 ` H. Peter Anvin
2026-02-13 17:47 ` Linus Torvalds
2026-02-13 18:27 ` Askar Safin
2026-02-13 18:39 ` Linus Torvalds
2026-02-13 20:00 ` H. Peter Anvin
2026-02-14 15:31 ` Askar Safin
2026-02-15 0:52 ` H. Peter Anvin
2026-02-14 12:15 ` Christian Brauner
2026-02-14 16:18 ` Linus Torvalds
2026-02-14 17:40 ` Al Viro
2026-02-17 8:35 ` Christian Brauner
2026-02-13 18:42 ` H. Peter Anvin
2026-02-13 20:08 ` H. Peter Anvin
2026-02-12 19:22 ` Al Viro
2026-02-13 17:34 ` Askar Safin
2026-02-13 22:28 ` Al Viro [this message]
2026-02-14 16:16 ` Askar Safin
2026-02-12 13:23 ` Askar Safin
2026-02-12 19:25 ` Al Viro
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