linux-ext4 - Protecting lost+found from rmdir by directory owner?

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Message-ID: <42bc44533e997531baa79c73867a942504122886.camel@interlinx.bc.ca>
Date: Tue, 16 Jan 2024 08:26:14 -0500
From: "Brian J. Murrell" <brian@...erlinx.bc.ca>
To: linux-ext4@...r.kernel.org
Subject: Protecting lost+found from rmdir by directory owner?

Let's say I create a new ext4 filesystem for exclusive use by alice and
when I mount it, say, on /mnt/alice I set the permissions so that alice
can work in that directory:

# mkfs.ext4 /dev/foo
# mount /dev/foo /mnt/alice
# chown alice:alice /mnt/alice
# chmod 775 /mnt/alice

But now /mnt/alice/lost+found is at the mercy of alice since she has
write permission for /mnt/alice.

[How] can I protect /mnt/alice/lost+found from removal by alice?

Thoughts?

b.

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