linux-kernel - The one and only "permission denied" in find /sys

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Message-ID: <cd81a57e-e2c1-03c5-d0da-f898babf92e7@landley.net>
Date:   Wed, 13 Oct 2021 15:12:16 -0500
From:   Rob Landley <rob@...dley.net>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>
Subject: The one and only "permission denied" in find /sys

There is exactly one directory in the whole of sysfs that a normal user can't
read (at least on my stock devuan laptop):

  $ find /sys -name potato
  find: ‘/sys/fs/pstore’: Permission denied

It's the "pstore" filesystem, it was explicitly broken by commit d7caa33687ce,
and the commit seems to say this was to fix an issue that didn't exist yet but
might someday.

Did whatever issue it was concerned about ever actually start happening? Why did
you not change the permissions on the files _in_ the directory so they weren't
world readable instead? Should /dev/shm stop being world ls-able as well?

Confused,

Rob