[refpolicy] labels on /dev/tty.*

Daniel J Walsh dwalsh at redhat.com
Fri Oct 24 14:52:24 UTC 2014

On 10/23/2014 08:14 AM, Christopher J. PeBenito wrote:
> On 10/22/2014 12:09 PM, Jason Zaman wrote:
>> Hi all,
>> I am confused about the labels on the tty dev nodes. I looked in refpol
>> and the only fcontext is:
>> /dev/.*tty[^/]* -c gen_context(system_u:object_r:tty_device_t,s0)
>> The implications of this are that everything is labelled with
>> tty_device_t but I am pretty sure this is wrong. I have seen several
>> different types of nodes which I think should have separate labels.
>> Ones that I am aware of (please add more or correct my understanding if
>> it is wrong)
>> /dev/tty0 -- The consoles (eg ctrl+alt+f1)
>> /dev/ttyS -- A physical serial port
>> /dev/ttyUSB0 -- A usb-to-serial port
>> /dev/ttyACM0 -- I have seen this for both usb-to-serial on embedded
>> microcontrollers as well as 3G modems and the like.
>> /dev/usb/tty.* -- I have no idea what this is, its not on my system but
>> it is labelled usbtty_device_t in refpol.
>> The label on tty0 seems correct, the label on ttyUSB0 and ttyACM0 should
>> probably be usbtty_device_t. As for what the label should be on ttyS0, I
>> am not sure.
>> Thoughts? I dont want to just send in a patch changing this before I
>> understand *exactly* what these are used for in case they break
>> something else.
> It seems more likely that usbtty_device_t should be dropped.  I don't
> see any reason for there to be a distinction based on the underlying
> hardware.
I agree.

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