Disable/enable USB storage device @ run time

[Mr.Jkate]

I need to disable/enable USB storage device @ run time on ubuntu 7.1
Any Idea ?

[cdenley]

I need to disable/enable USB storage device @ run time on ubuntu 7.1
Any Idea ?

I haven't tried it, but I think this would work.

sudo bash -c "echo blacklist usb-storage>/etc/modprobe.d/disable-usbstor"

[unutbu]

One way would be to compile a kernel with no USB storage support, and then add a GRUB boot stanza for the new kernel. The advantage of doing it this way is that compiling kernels is a well documented process, and so is editing GRUB menu.lst, so all the pieces to the solution are generally available. The disadvantage is you'll be installing maybe ~100MB of files just to disable USB storage. You might be able to cut down on the bloat with a lot of symlinks, but I'm not confident I could describe the process and be right at the same time.

There may be a better way -- something along the lines of what cdenley suggested -- by editing some configuration file. The particular command cdenley suggested will (I think) work if you run the command *before* rebooting when you want USB disabled. But when you want to re-enable USB storage, you'd have to remove the /etc/modprobe.d/disable-usbstor file.

If there is a better way along these lines, I do not know it.

A third possibility is the following hack: You can hook up a GRUB boot stanza to a different runlevel.
The advantage here is you can control the behavior by select a boot option in the GRUB menu, but unlike when compiling a new kernel, there will not be tons of files installed. The disadvantage of this hack is that it attacks the problem too late in the boot process -- the usb-storage kernel module will have already been loaded into the kernel, so the hack simply runs a script to unmount your USB partitions and then remove the usb-storage module.

Well, for what it's worth, here is the hack:



Hook up a GRUB boot stanza to runlevel 3
(Your default boot is runlevel 2, we can leave that alone for when you want USB storage enabled. We now modify the runlevel 3 boot process to disable USB storage.)


Tell your linux box what to do if it encounters the word "runlevel3" in its boot command:
gksu gedit /etc/event.d/rc-default
Change this:
if grep -q -w -- "-s\|single\|S" /proc/cmdline; then
telinit S
elif [ -r /etc/inittab ]; then

to
if grep -q -w -- "-s\|single\|S" /proc/cmdline; then
telinit S
elif grep -q -w -- "runlevel3" /proc/cmdline; then
telinit 3
elif [ -r /etc/inittab ]; then

Save and Quit gedit.

Put "runlevel3" in a new GRUB boot stanza:

gksu gedit /boot/grub/menu.lst

About 2/3 of the way down the file you will find something like this


title Ubuntu 7.10, kernel 2.6.22-14-generic
root (hd0,2)
kernel /boot/vmlinuz-2.6.22-14-generic root=UUID=03a507ee-cdac-4bd9-b438-eccd616b66ed ro
initrd /boot/initrd.img-2.6.22-14-generic
quiet

Make a duplicate copy of your boot stanza, and then modify the duplicate by changing the title to something like "No USB", and adding "runlevel3" to the end of the kernel line:

title No USB
root (hd0,2)
kernel /boot/vmlinuz-2.6.22-14-generic root=UUID=03a507ee-cdac-4bd9-b438-eccd616b66ed ro runlevel3
initrd /boot/initrd.img-2.6.22-14-generic
quiet

Okay, now when you boot, you can press ESC to get to the GRUB menu, and you'll see both your regular boot line, and a "No USB" boot line. Now to make runlevel 3 do something different than runlevel 2:


Create a /etc/init.d/disable-usbstorage script


gksu gedit /etc/init.d/disable-usbstorage

#! /bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin
. /lib/lsb/init-functions

case "$1" in
start)
umount /dev/sdbX
modprobe -r usb-storage
;;
stop)
modprobe usb-storage
;;
*)
echo "Usage: $0 start|stop" >&2
exit 3
;;
esac

Change /dev/sdbX to the real device name of your USB storage device.

Link the script to /etc/rc3.d, so it will be run in runlevel 3.
sudo ln -s /etc/init.d/disable-usbstorage /etc/rc3.d/S99disable-usbstorage