linux-kernel - ip netns exec namespace ls -l /proc/pid/fd prepends "/root" to the filename.

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Message-ID: <4c5a2ef5827f471cba84a7c74279f53a@AcuMS.aculab.com>
Date:   Thu, 25 Aug 2022 18:38:08 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: ip netns exec namespace ls -l /proc/pid/fd prepends "/root" to the
 filename.

If a process inside a network namespace calls readlink() on
/proc/pid/fd/n (for any pid) then the returned string is
prefixed by "/root".

So you get "/root/sys/console" or "/root/var/log/fred" etc.

There seems to be an extra call to prepend_name() called
from prepend_path() from d_path().

This seems decidedly wrong, especially since /root usually
exists.

Even it is were reporting a file outside a chroot (opened
before the chroot) prepending "/root" would be wrong.

Kernel is 5.10.132 (LTS before the retbleed breakages!)

	David

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