#!/bin/bash
#
# USB hotplug switcher.
# See https://links.fluxo.info/tags/badusb
#     https://www.kernel.org/doc/Documentation/usb/authorization.txt
#     http://marc.info/?l=git-commits-head&m=131166366113680&w=2
#     https://github.com/dkopecek/usbguard (alternative approach)

# Parameters
BASENAME="`basename $0`"

# Set hotplug state
function usb_set_state {
  echo "Applying at /sys/module/usbcore/parameters/authorized_default..."
  sudo su -c "echo $1 > /sys/module/usbcore/parameters/authorized_default"

  for bus in /sys/bus/usb/devices/usb*; do
    echo "Applying at ${bus}/authorized_default..."
    sudo su -c "echo $1 > ${bus}/authorized_default"
  done
}

# Dispatch
if [ "$BASENAME" == 'usb-enable' ]; then
  usb_set_state 1
elif [ "$BASENAME" == 'usb-disable' ]; then
  usb_set_state 0
elif [ "$BASENAME" == 'usb-status' ]; then
  status="`cat /sys/module/usbcore/parameters/authorized_default`"

  # The "authorized_default" module parameter of usbcore controls the default
  # for the authorized_default variable of each USB host controller.
  #
  # -1 is authorized for all devices except wireless (default, old behaviour)
  # 0 is unauthorized for all devices
  # 1 is authorized for all devices
  if [ "$status" == "0" ]; then
    echo "Hotplug disabled."
  elif [ "$status" == "1" ]; then
    echo "Hotplug enabled."
  elif [ "$status" == "-1" ]; then
    echo "Hotplug enabled except wireless"
  fi
fi