tree 0e3f9cbfdca5d6a32aae5dee05f74b2a48fd4095
parent 04171532583052935121a3e33550cc39ef2625ec
author Luigi Semenzato <semenzato@chromium.org> 1389399968 -0800
committer chrome-internal-fetch <chrome-internal-fetch@google.com> 1392173400 +0000

CHERRY-PICK: vboot: use recovery button as dev mode switch confirmation

We don't allow ENTER from a USB keyboard as the confirmation
in the switch from normal to developer mode.

For devices that have a physical recovery button, we require
a recovery button press instead.  For other devices, we
require that ENTER be pressed on the internal keyboard.

This prevents an "evil keyboard" attack in which a USB keyboard
(or other USB device pretending to be a keyboard) sends a
control-D/ENTER sequence shortly after every boot (followed
by more evil keys).  In that situation, when users power-on in
recovery mode, they will be forced to dev mode even if it
was not their intention.  Further attacks are easy at
that point.

TESTING.  On a device:

1. powered on with recovery button pressed -> booted in recovery mode
2. pressed control-D on external USB keyboard -> got to ToDev? screen
3. pressed ENTER -> system beeped
4. pressed recovery button -> system rebooted in DEV mode

... all as expected

Also:

1. powered on with recovery button pressed and HELD recovery button
2. pressed control-D -> system beeped

BUG=chrome-os-partner:21729
TEST=manual (see commit message)
BRANCH=none

Change-Id: I352f31d587c1b916b678e382ca56df24b9ab1330
Original-Change-Id: Ib986d00d4567c2d447f8bbff0e5ccfec94596aa7
Reviewed-on: https://chromium-review.googlesource.com/183053
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
Commit-Queue: Luigi Semenzato <semenzato@chromium.org>
Tested-by: Luigi Semenzato <semenzato@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/185547
Reviewed-by: Shawn Nematbakhsh <shawnn@chromium.org>
Commit-Queue: Gediminas Ramanauskas <gedis@chromium.org>
Tested-by: Gediminas Ramanauskas <gedis@chromium.org>