From: Al Viro <viro@zeniv.linux.org.uk>
To: Christian Brauner <brauner@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>,
jack@suse.cz, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, josef@toxicpanda.com,
wojciech.gladysz@infogain.com, ebiederm@xmission.com,
kees@kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] exec: drop a racy path_noexec check
Date: Tue, 6 Aug 2024 00:38:04 +0100 [thread overview]
Message-ID: <20240805233804.GI5334@ZenIV> (raw)
In-Reply-To: <20240805-denkspiel-unruhen-c0ec00f5d370@brauner>
On Mon, Aug 05, 2024 at 05:35:35PM +0200, Christian Brauner wrote:
> > To my reading that path_noexec is still there only for debug, not
> > because of any security need.
>
> I don't think it's there for debug. I think that WARN_ON_ONCE() is based
> on the assumption that the mount properties can't change. IOW, someone
> must've thought that somehow stable mount properties are guaranteed
> after may_open() irrespective of how the file was opened. And in that
> sense they thought they might actually catch a bug.
That would be a neat trick, seeing that there'd never been anything to
prevent mount -o remount,exec while something is executed on the
filesystem in question.
> But having it in there isn't wrong. In procfs permission/eligibility
> checks often are checked as close to the open as possible. Worst case
> it's something similar here. But it's certainly wrong to splat about it.
Bury it.
next prev parent reply other threads:[~2024-08-05 23:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-01 12:07 [PATCH] kernel/fs: last check for exec credentials on NOEXEC mount Wojciech Gładysz
2024-08-01 14:07 ` Josef Bacik
2024-08-01 15:15 ` Mateusz Guzik
2024-08-02 15:58 ` Josef Bacik
2024-08-03 6:29 ` Mateusz Guzik
2024-08-05 9:26 ` Christian Brauner
2024-08-05 13:17 ` [PATCH] exec: drop a racy path_noexec check Mateusz Guzik
2024-08-05 15:35 ` Christian Brauner
2024-08-05 20:21 ` Kees Cook
2024-08-05 23:38 ` Al Viro [this message]
2024-08-05 23:41 ` Al Viro
2024-08-06 7:06 ` Christian Brauner
2024-08-07 21:06 ` Kees Cook
2024-08-02 3:28 ` [PATCH] kernel/fs: last check for exec credentials on NOEXEC mount Kees Cook
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