linux/Documentation/DocBook
Reilly Grant d883f52e1f usb: devio: Add ioctl to disallow detaching kernel USB drivers.
The new USBDEVFS_DROP_PRIVILEGES ioctl allows a process to voluntarily
relinquish the ability to issue other ioctls that may interfere with
other processes and drivers that have claimed an interface on the
device.

This commit also includes a simple utility to be able to test the
ioctl, located at Documentation/usb/usbdevfs-drop-permissions.c

Example (with qemu-kvm's input device):

    $ lsusb
    ...
    Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd

    $ usb-devices
    ...
    C:  #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA
    I:  If#= 0 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=00 Prot=02 Driver=usbhid

    $ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002
    OK: privileges dropped!
    Available options:
    [0] Exit now
    [1] Reset device. Should fail if device is in use
    [2] Claim 4 interfaces. Should succeed where not in use
    [3] Narrow interface permission mask
    Which option shall I run?: 1
    ERROR: USBDEVFS_RESET failed! (1 - Operation not permitted)
    Which test shall I run next?: 2
    ERROR claiming if 0 (1 - Operation not permitted)
    ERROR claiming if 1 (1 - Operation not permitted)
    ERROR claiming if 2 (1 - Operation not permitted)
    ERROR claiming if 3 (1 - Operation not permitted)
    Which test shall I run next?: 0

After unbinding usbhid:

    $ usb-devices
    ...
    I:  If#= 0 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=00 Prot=02 Driver=(none)

    $ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002
    ...
    Which option shall I run?: 2
    OK: claimed if 0
    ERROR claiming if 1 (1 - Operation not permitted)
    ERROR claiming if 2 (1 - Operation not permitted)
    ERROR claiming if 3 (1 - Operation not permitted)
    Which test shall I run next?: 1
    OK: USBDEVFS_RESET succeeded
    Which test shall I run next?: 0

After unbinding usbhid and restricting the mask:

    $ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002
    ...
    Which option shall I run?: 3
    Insert new mask: 0
    OK: privileges dropped!
    Which test shall I run next?: 2
    ERROR claiming if 0 (1 - Operation not permitted)
    ERROR claiming if 1 (1 - Operation not permitted)
    ERROR claiming if 2 (1 - Operation not permitted)
    ERROR claiming if 3 (1 - Operation not permitted)

Signed-off-by: Reilly Grant <reillyg@chromium.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-03-05 12:05:01 -08:00
..
media [media] Postpone the addition of MEDIA_IOC_G_TOPOLOGY 2016-01-11 12:35:17 -02:00
.gitignore
80211.tmpl
alsa-driver-api.tmpl
crypto-API.tmpl
debugobjects.tmpl
device-drivers.tmpl [media] DocBook: Move media-framework.txt contents to media-device.h 2016-01-11 12:19:04 -02:00
deviceiobook.tmpl
filesystems.tmpl
gadget.tmpl
genericirq.tmpl
gpu.tmpl apple-gmux: Add initial documentation 2016-01-11 15:56:23 +01:00
iio.tmpl
kernel-api.tmpl
kernel-hacking.tmpl
kernel-locking.tmpl
kgdb.tmpl
libata.tmpl
librs.tmpl
lsm.tmpl
Makefile
media_api.tmpl [media] use https://linuxtv.org for LinuxTV URLs 2015-12-04 10:38:59 -02:00
mtdnand.tmpl mtd: nand: update the documentation to reflect framework changes 2015-12-18 11:26:01 -08:00
networking.tmpl
rapidio.tmpl
regulator.tmpl
s390-drivers.tmpl
scsi.tmpl
sh.tmpl
stylesheet.xsl
tracepoint.tmpl
uio-howto.tmpl
usb.tmpl usb: devio: Add ioctl to disallow detaching kernel USB drivers. 2016-03-05 12:05:01 -08:00
w1.tmpl
writing-an-alsa-driver.tmpl
writing_musb_glue_layer.tmpl
writing_usb_driver.tmpl
z8530book.tmpl