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Re: lircd daemon as regular user => device access problems




On Sun, 12 Feb 2017 at 11:33:22 +0100, Alec Leamas wrote:
> On 12/02/17 11:16, Bastien Roucaries wrote:
> > Last time braille stuff break (brick) a FPGA device with a jtag adaptator (serial to jtag). So i really dislike package that bind to all char device.
> >
> > Btw if you do this you need a break on braille stuff...
> 
> Now, we are not talking about all character devices, it's about USB-based
> character devices. Does this address your concerns?
> 
> If not, blacklisting probably is the easiest path - I'm happy to blacklist
> any USB ids if you just provide them. Or, if that's better, relevant udev
> info to make a matching rule.

This is sounding a lot like ModemManager, which has recurring problems
with the inability to distinguish between modems and non-modem
serial-attached devices (especially since both will often use a commodity
USB/serial converter with generic device IDs, like a FTDI or PL2303 device)
without probing them by sending AT commands that could be interpreted in
unintended ways by non-modems (like Braille devices, embedded devices'
serial consoles, and Bastien's JTAG adapter).

/lib/udev/??-mm-*.rules are probably of interest. ModemManager
implements a whitelist (devices that are definitely modems), a blacklist
(devices that are definitely not modems), and a greylist (devices that
might be modems, but will only be probed by ModemManager if the user
explicitly requests it via some GUI or CLI frontend).

    S