Comment # 8 on bug 1093378 from Stefan Br�ns

(In reply to Matwey Kornilov from comment #5)
> So, the issue is that udev default rules allows uncontrollable device
> rebinding.
> What if we drop this rules and left it for users to allow device rebinding
> based on USB device serial number (for instance)? There could be template in
> /etc/udev/rules.d to fill serial and uncoment.

Silabs (CP210x) USB-serial chips can be reprogrammed
(http://cp210x-program.hg.sourceforge.net/hgweb/cp210x-program/cp210x-program/)
with unique serial numbers, but everything you get from your friendly
least-untrusted internet seller has a "0" as its serial number.

I don't know about the Braille devices, but if these vendors are incapable to
request a Product ID from the chip vendor, they don't likely care for useful
serial numbers (other than "1234ABCD").

ModemManager IIRC actually has a sensible approach, it white- or graylists
items. Whitelisted items are guaranteed to be modems (e.g. by correct USB
VID/PID, interface), graylisted items are allowed to be probed manually.


We have two/three? different classes of services using these "serial" ports:
- programms acessing the port on request, e.g. argyllcms, sigrok, avrdude
- daemons running as a system service (upower, ModemManager, gpsd, ...)
- daemons running in a user session?

Critical are the ones in the second group, as these may be fighting over the
device.