linuxbashkernelusbudev

UDEV Rule to exclude "bus/usb/001/*" folder

I'm trying to create simple udev rules to block all devices but mass storage being connected on a specific port (RASPBERRY PI 4).

I came up with the following rules :

Allowing USB drives :

KERNEL=="sd?", ENV{DEVTYPE}=="disk", ATTRS{devpath}=="1.3", SYMLINK+="USBInputDISK", ATTR{authorized}:="1"
KERNEL=="sd??", ENV{DEVTYPE}=="partition", ATTRS{devpath}=="1.3", SYMLINK+="USBInputPARTITION", ATTR{authorized}:="1"

Blocking everything else :

ENV{DEVTYPE}!="disk", ENV{DEVTYPE}!="partition", ATTRS{devpath}=="1.3", SYMLINK+="BadUSBInput", ATTR{authorized}:="0"

The only issue with this is that the blocking rule takes over the allowing one as it will block "/dev/bus/usb/001/***". Therefore, I'm trying to avoid this. my idea is to add a test in the udev rule on the N: flag. This is because when I run :

udevadm info -q all /dev/bus/usb/001/016

I get a line that states N: bus/usb/001/016

So I would like to add a statement to the udev rule that states "N:"!="/bus/usb/001/*". I don't know how though and couldn't find the answer online.

I tried something with ENV{DEVNAME}!="/dev/bus/*" which does not work for some reason.

Any idea ? Thanks !

Solution

  • Got it.

    ATTRS{devpath}=="1.3", KERNEL=="hid*", RUN+="/bin/bash -c 'echo 0 > /sys/bus/usb/devices/1-1.3/authorized'"

    This is a working way to block inputs (keyboards, mouse, rubber duckies) on a com port while allowing mass storage usb thumb drives.