Re: permissions of /proc/tty/driver

[Christoph Hellwig <hch@lst.de>]

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?