We use a few bytes of battery-backed nvram to save some flags across
reboots. However if the battery discharges completely, these flags are lost.
There aren't any security issues with that since they reset to safe values,
but some of the flags are used to configure how the system boots in
dev-mode.
If a dev-mode user has completely replaced ChromeOS with some other OS, then
she often needs to set the dev_boot_usb and/or dev_boot_legacy flags as well
in order to boot it using Ctrl-U or Ctrl-L. If the battery dies, then those
flags are cleared, and the only way to make the Chromebook boot again is by
going through recovery, which wipes the disk.
This change uses a new NV space in the TPM to back up some of the nvram
flags. These nvram fields will be backed up:
block_devmode
dev_boot_legacy
dev_boot_signed_only
dev_boot_usb
fwupdate_tries
loc_idx
Because writing to the TPM space is slow and limited to an unspecified but
finite number of cycles, we only back up the fields when specifically
requested by the new backup_nvram_request flag. This flag will be set by
crossystem whenever it is used to change any of the fields listed above. The
backup will be attempted at the NEXT boot (because the TPM is locked after
booting), and the backup_nvram_request flag will be cleared if the backup
was successfull.
Note that this CL is for Top of Trunk only. The firmware will create the
required TPM spaces on systems that have never been booted, but we don't yet
have a secure or reliable method to update existing systems.
FYI, on Link, determining that the TPM's backup NV space doesn't exist adds
about 6ms to the boot time. If it does exist, the backup_nvram_request flag
is cleared automatically so it won't check until it's set again.
BUG=chromium:362105
BRANCH=ToT (only!)
TEST=manual
Testing this is a long and involved process. Read on...
First, there are host-side tests for it. In the chroot:
cd src/platform/ec
make runtests
Second, to test on a completely NEW system that was first booted with a BIOS
that contains this CL, do this:
Enter dev-mode
Use crossystem to set values for the fields listed above
Confirm that "backup_nvram_request" is set to 1
Reboot
Use crossystem to confirm that "backup_nvram_request" is now 0
Remove the battery and the AC
Reattach either battery or AC so it will boot again
Use crossystem to confirm that the backed up fields are still good, while
the others have been reset to default values
Switch to normal mode
Remove the battery and the AC
Reattach either battery or AC so it will boot again
Look at the bios info in chrome://system to see what crossystem says
Confirm that the dev_boot_* flags are all 0, while the others are restored
Third, to set things up to test this on an existing system (I used Link),
you have update the BIOS, delete both the Kernel and Firmware NV spaces in
the TPM, then reboot so that the BIOS will create the Backup, Kernel, and
Firmware spaces. It will only do that if they're all missing.
Open it up, disable write-protect, attach a servo, etc.
Switch to dev-mode, log in.
Run make_dev_firmware.sh
Reboot in recovery mode, and insert a USB stick with a test image on it.
NOTE: In order to fiddle with the TPM, we'll *always* have to boot in
recovery mode, since that's the only time the TPM is left unlocked. That's
NOT the same as pressing Ctrl-U at the scary boot screen. The rest of
these steps assume you've booted in recovery mode and are running from the
test image on the USB stick.
Run
make_dev_ssd.sh --remove_rootfs_verification --recovery_key
Reboot (recovery mode)
Run
mv /etc/init/tcsd.conf /etc/init/tcsd.conf.disabled
Reboot (recovery mode).
Run "tpmc getvf". It should say
deactivated 0
disableForceClear 0
physicalPresence 1
physicalPresenceLock 0
bGlobalLock 0
Run "tpmc geto". It should say
Owned: no
Now you'll need to build the "tpm-nvtool" utility. In the chroot:
cd src/third_party/tpm/nvtool
make
Copy that to the DUT, in /usr/local/bin.
Now run
tcsd
tpm-nvtool --list | grep Index
You may see a number of spaces, but you should at least see these:
# NV Index 0x00001007
# NV Index 0x00001008
Run
tpm_takeownership
It will prompt you for two passwords (and confirm each one). Respond with
something you can remember like "google".
Run
tpm-nvtool --release --index 0x1007 --owner_password "google"
tpm-nvtool --release --index 0x1008 --owner_password "google"
Verify that it worked with
tpm-nvtool --list | grep Index
Power off.
Using servo, flash the new BIOS that has this CL in it.
Power on, normally this time (not recovery mode). If all goes well, it
should create the correct NV spaces and boot into the SSD. Copy tpm-nvtool
into this image too, and run
tpm-nvtool --list | grep Index
You should now see at least these spaces:
# NV Index 0x00001007
# NV Index 0x00001008
# NV Index 0x00001009
Now you're ready to test the backup/recover feature.
Change-Id: I00031fa0774720147327e2ae0f37e26b34b86341
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/202138
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
These function prototypes changed recently and the mocked driver is not
building any longer.
BUG=none
BRANCH=none
TEST=successful build with MOCK_TPM=1
Change-Id: Iaaf2d2c2883add7a478d7ee887b06e45c65e1bb2
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/65338
Reviewed-by: Stefan Reinauer <reinauer@google.com>
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
SetupTPM no longer uses recovery_mode parameter for anything other than
a debug print. This change moves the debug print to a caller function,
then removes recovery_mode from SetupTPM and some caller functions that
no longer have a use for it.
BUG=chrome-os-partner:20913.
TEST=Manual. Boot factory install shim in recovery mode and verify TPM
clear operations succeed. Boot in dev mode and verify "Lock physical
presence" print on UART.
BRANCH=None.
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: I2f671f6680a6e67cf722855e659e99752bc0783c
Reviewed-on: https://gerrit.chromium.org/gerrit/62916
Reviewed-by: Randall Spangler <rspangler@chromium.org>
RollbackKernelLock previously checked a global to determine recovery
mode state. Since we have two copies of vboot_reference in firmware
(in coreboot and depthcharge), this creates a problem with
synchronization. Remove the global entirely and instead pass the
recovery state to RollbackKernelLock.
BUG=chrome-os-partner:20913.
TEST=Manual. Boot factory install shim in recovery mode and verify TPM
clear operations succeed. Boot in dev mode and verify "Lock physical
presence" print on UART.
BRANCH=FalcoPeppy.
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: I4e751d4a9ca60cd57c5c662ce86eba595fb22ba2
Reviewed-on: https://gerrit.chromium.org/gerrit/62874
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
This adds two new flags to crossystem:
clear_tpm_owner_request
clear_tpm_owner_done
The first one requests that the firmware clear the TPM owner on the
next boot. When the firmware does this, it will set
clear_tpm_owner_request=0, and set clear_tpm_owner_done=1. The OS can
use the done-flag as a hint that trusted things guarded by the TPM are
no longer trustable.
BUG=chromium-os:31974
TEST=manual
crossystem
// both flags initially 0
crossystem clear_tpm_owner_request=1
crossystem clear_tpm_owner_done=1
// request=1, done=0; done can be cleared but not set by crossystem
reboot
tpmc getownership
// owned=no
crossystem
// request=0, done=1
crossystem clear_tpm_owner_done=0
crossystem
// both flags 0 again
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Change-Id: I49f83f3c39c3efc3945116c51a241d255c2e42cd
Reviewed-on: https://gerrit.chromium.org/gerrit/25646
Fixes build failure seen in u-boot for tegra2 seaboard:
.../vboot_fw.a(vboot_api_kernel.o): In function 'VbConfirmChangeDevMode':
(.text+0x84): undefined reference to 'SetVirtualDevMode'
BUG=None
TEST=`emerge-tegra2_seaboard chromeos-u-boot` works again
Change-Id: If374a78218fc8a7921ff8dddde163138969e0876
Reviewed-on: https://gerrit.chromium.org/gerrit/24948
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
BUG=chrome-os-partner:9706
TEST=manual
Currently, Link is the only platform that enables this feature.
To enter dev-mode:
Boot into recovery mode using the magic key chord. At the Insert screen,
press Ctrl-D. You'll be asked if you want to enter developer mode. If you
then press ENTER, it will reboot with dev-mode enabled. If you press SPACE
or ESC, it will return to the Insert screen.
If you enter recovery mode through any other means, or if dev-mode is
already enabled, pressing Ctrl-D at the Insert screen will have no effect.
To return to normal mode:
Reboot. At the Dev screen, press ENTER or SPACE. It will reboot to
recovery mode and ask you if you want to return to normal mode. If you
press ESC or power off, you'll still be in dev-mode. Press ENTER or SPACE,
and it will reboot into normal mode (of course, if you've messed up your
images while in dev-mode, you'll just come right back to recovery mode
again).
You can also request a direct return to normal mode by running
crossystem disable_dev_request=1
and rebooting.
Change-Id: I435905855a6c39932ee466cc046bdc4c4c860f98
Reviewed-on: https://gerrit.chromium.org/gerrit/24160
Tested-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Commit-Ready: Bill Richardson <wfrichar@chromium.org>
If VbInit() is instructed to look at a virtual dev-mode switch, then it will
use value contained in the TPM's firmware space instead of a hardware GPIO
to determine if developer mode is enabled.
This change just makes it look. It doesn't provide a way to actually set
the value in the TPM. VbInit() isn't being told to look yet, either. Those
changes are coming.
BUG=chrome-os-partner:9706
TEST=none
The usual sanity-check applies:
make
make runtests
But to actually test that this stuff is working IRL requires special tweaks
to other components and monitoring the serial debug output from both EC and
CPU. We'll save the hands-on tests for when it's all done.
Change-Id: Ie485ad2180224e192238bf2a5dbf95bbcb9130f9
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/23067
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Try #2, now that ARM has the fix from http://gerrit.chromium.org/gerrit/4667
This cleans up the TPM calls inside vboot_reference.
* TPM calls share mode code between boot modes.
* Better handling for TPM_E_MUST_REBOOT, particularly in recovery mode.
* TAB screen shows current TPM versions.
No changes required to the wrapper API; these changes are internal to vboot.
BUG=chromium-os:18084
TEST=make && make runtests; built for both alex and tegra2-seaboard
Original-Change-Id: I2a52066f2889210af83409872b10f9d6380470af
(cherry picked from commit da55560cddcf7a1aa8a881cdf52792a21a01e766)
Change-Id: I120797145772116f09b8125b9e56fdbb11dc16b3
Reviewed-on: http://gerrit.chromium.org/gerrit/4671
Tested-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
This cleans up the TPM calls inside vboot_reference.
* TPM calls share mode code between boot modes.
* Better handling for TPM_E_MUST_REBOOT, particularly in recovery mode.
* TAB screen shows current TPM versions.
No changes required to the wrapper API; these changes are internal to vboot.
BUG=chromium-os:18084
TEST=make && make runtests; built for both alex and tegra2-seaboard
Change-Id: I2a52066f2889210af83409872b10f9d6380470af
Reviewed-on: http://gerrit.chromium.org/gerrit/4611
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: Gaurav Shah <gauravsh@chromium.org>
Tested-by: Randall Spangler <rspangler@chromium.org>
