Re: permissions of /proc/tty/driver

From: Christoph Hellwig
Date: Sun Jan 16 2005 - 07:06:28 EST


On Fri, Jan 14, 2005 at 06:45:25PM +0100, Thomas Viehmann wrote:
> Hi.
>
> This may not be stritly on topic, but I couln't figure out a better
> place to ask:
>
> During the packaging of an application, I have the following problem:
> I would like to run a daemon as non-root. The daemon likes to
> (continually) check /proc/tty/driver/usbserial to see whether or not
> interesting USB devices are connected. The permissions of this actual
> file is (on a kernel compiled from Debian's kernel-source-2.6.10) 0444,
> so this isn't a problem. However, the parent directory /proc/tty/driver
> is 0500. I'm not sure whether this is related to Debian DSAs 358 or 423
> (where /proc/tty/driver/serial is mentioned as leaking sensitive
> information), to me the contents of usbserial look innocent enough.
> Do you have any hints on what might be a good solution?

The permissions on the directory look indeed too strict to me. It might
be better to just use strict permissions on /proc/tty/driver/serial
indeed.

Counter-question: What information is available in
/proc/tty/driver/usbserial but not in sysfs?
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