From a53a0b040f45a1086515e7a5c8a8326c0b1d1f74 Mon Sep 17 00:00:00 2001 From: Luigi Semenzato Date: Fri, 10 Jan 2014 16:26:08 -0800 Subject: 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 panther 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 CQ-DEPEND=CL:182420,CL:182946,CL:182357 Change-Id: Ib986d00d4567c2d447f8bbff0e5ccfec94596aa7 Reviewed-on: https://chromium-review.googlesource.com/182241 Reviewed-by: Luigi Semenzato Tested-by: Luigi Semenzato Commit-Queue: Luigi Semenzato --- firmware/stub/vboot_api_stub.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'firmware/stub') diff --git a/firmware/stub/vboot_api_stub.c b/firmware/stub/vboot_api_stub.c index e82be5b2..913cac15 100644 --- a/firmware/stub/vboot_api_stub.c +++ b/firmware/stub/vboot_api_stub.c @@ -57,6 +57,16 @@ uint32_t VbExKeyboardRead(void) return 0; } +uint32_t VbExKeyboardReadWithFlags(uint32_t *flags_ptr) +{ + return 0; +} + +uint32_t VbExGetSwitches(uint32_t mask) +{ + return 0; +} + uint32_t VbExIsShutdownRequested(void) { return 0; -- cgit v1.2.1