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u-boot/test/py/tests/test_vboot.py
Thirupathaiah Annapureddy feaeee8b5f test: vboot: add tests for multiple required keys 
This patch adds vboot tests to verify the support for multiple
required keys using new required-mode DTB policy.

This patch also fixes existing test where dev
key is assumed to be marked as not required, although
it is marked as required.

Note that this patch re-added sign_fit_norequire().
sign_fit_norequire() was removed as part of the following:
commit b008677daf ("test: vboot: Fix pylint errors").
This patch leverages sign_fit_norequire() to fix the
existing bug.

Signed-off-by: Thirupathaiah Annapureddy <thiruan@linux.microsoft.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2020-10-12 21:30:37 -04:00

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# SPDX-License-Identifier: GPL-2.0+
# Copyright (c) 2016, Google Inc.
#
# U-Boot Verified Boot Test
"""
This tests verified boot in the following ways:
For image verification:
- Create FIT (unsigned) with mkimage
- Check that verification shows that no keys are verified
- Sign image
- Check that verification shows that a key is now verified
For configuration verification:
- Corrupt signature and check for failure
- Create FIT (with unsigned configuration) with mkimage
- Check that image verification works
- Sign the FIT and mark the key as 'required' for verification
- Check that image verification works
- Corrupt the signature
- Check that image verification no-longer works
Tests run with both SHA1 and SHA256 hashing.
"""
import struct
import pytest
import u_boot_utils as util
import vboot_forge
TESTDATA = [
['sha1', '', None, False],
['sha1', '', '-E -p 0x10000', False],
['sha1', '-pss', None, False],
['sha1', '-pss', '-E -p 0x10000', False],
['sha256', '', None, False],
['sha256', '', '-E -p 0x10000', False],
['sha256', '-pss', None, False],
['sha256', '-pss', '-E -p 0x10000', False],
['sha256', '-pss', None, True],
['sha256', '-pss', '-E -p 0x10000', True],
]
@pytest.mark.boardspec('sandbox')
@pytest.mark.buildconfigspec('fit_signature')
@pytest.mark.requiredtool('dtc')
@pytest.mark.requiredtool('fdtget')
@pytest.mark.requiredtool('fdtput')
@pytest.mark.requiredtool('openssl')
@pytest.mark.parametrize("sha_algo,padding,sign_options,required", TESTDATA)
def test_vboot(u_boot_console, sha_algo, padding, sign_options, required):
"""Test verified boot signing with mkimage and verification with 'bootm'.
This works using sandbox only as it needs to update the device tree used
by U-Boot to hold public keys from the signing process.
The SHA1 and SHA256 tests are combined into a single test since the
key-generation process is quite slow and we want to avoid doing it twice.
"""
def dtc(dts):
"""Run the device tree compiler to compile a .dts file
The output file will be the same as the input file but with a .dtb
extension.
Args:
dts: Device tree file to compile.
"""
dtb = dts.replace('.dts', '.dtb')
util.run_and_log(cons, 'dtc %s %s%s -O dtb '
'-o %s%s' % (dtc_args, datadir, dts, tmpdir, dtb))
def run_bootm(sha_algo, test_type, expect_string, boots):
"""Run a 'bootm' command U-Boot.
This always starts a fresh U-Boot instance since the device tree may
contain a new public key.
Args:
test_type: A string identifying the test type.
expect_string: A string which is expected in the output.
sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
use.
boots: A boolean that is True if Linux should boot and False if
we are expected to not boot
"""
cons.restart_uboot()
with cons.log.section('Verified boot %s %s' % (sha_algo, test_type)):
output = cons.run_command_list(
['host load hostfs - 100 %stest.fit' % tmpdir,
'fdt addr 100',
'bootm 100'])
assert expect_string in ''.join(output)
if boots:
assert 'sandbox: continuing, as we cannot run' in ''.join(output)
else:
assert('sandbox: continuing, as we cannot run'
not in ''.join(output))
def make_fit(its):
"""Make a new FIT from the .its source file.
This runs 'mkimage -f' to create a new FIT.
Args:
its: Filename containing .its source.
"""
util.run_and_log(cons, [mkimage, '-D', dtc_args, '-f',
'%s%s' % (datadir, its), fit])
def sign_fit(sha_algo, options):
"""Sign the FIT
Signs the FIT and writes the signature into it. It also writes the
public key into the dtb.
Args:
sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
use.
options: Options to provide to mkimage.
"""
args = [mkimage, '-F', '-k', tmpdir, '-K', dtb, '-r', fit]
if options:
args += options.split(' ')
cons.log.action('%s: Sign images' % sha_algo)
util.run_and_log(cons, args)
def sign_fit_norequire(sha_algo, options):
"""Sign the FIT
Signs the FIT and writes the signature into it. It also writes the
public key into the dtb. It does not mark key as 'required' in dtb.
Args:
sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
use.
options: Options to provide to mkimage.
"""
args = [mkimage, '-F', '-k', tmpdir, '-K', dtb, fit]
if options:
args += options.split(' ')
cons.log.action('%s: Sign images' % sha_algo)
util.run_and_log(cons, args)
def replace_fit_totalsize(size):
"""Replace FIT header's totalsize with something greater.
The totalsize must be less than or equal to FIT_SIGNATURE_MAX_SIZE.
If the size is greater, the signature verification should return false.
Args:
size: The new totalsize of the header
Returns:
prev_size: The previous totalsize read from the header
"""
total_size = 0
with open(fit, 'r+b') as handle:
handle.seek(4)
total_size = handle.read(4)
handle.seek(4)
handle.write(struct.pack(">I", size))
return struct.unpack(">I", total_size)[0]
def create_rsa_pair(name):
"""Generate a new RSA key paid and certificate
Args:
name: Name of of the key (e.g. 'dev')
"""
public_exponent = 65537
util.run_and_log(cons, 'openssl genpkey -algorithm RSA -out %s%s.key '
'-pkeyopt rsa_keygen_bits:2048 '
'-pkeyopt rsa_keygen_pubexp:%d' %
(tmpdir, name, public_exponent))
# Create a certificate containing the public key
util.run_and_log(cons, 'openssl req -batch -new -x509 -key %s%s.key '
'-out %s%s.crt' % (tmpdir, name, tmpdir, name))
def test_with_algo(sha_algo, padding, sign_options):
"""Test verified boot with the given hash algorithm.
This is the main part of the test code. The same procedure is followed
for both hashing algorithms.
Args:
sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
use.
padding: Either '' or '-pss', to select the padding to use for the
rsa signature algorithm.
sign_options: Options to mkimage when signing a fit image.
"""
# Compile our device tree files for kernel and U-Boot. These are
# regenerated here since mkimage will modify them (by adding a
# public key) below.
dtc('sandbox-kernel.dts')
dtc('sandbox-u-boot.dts')
# Build the FIT, but don't sign anything yet
cons.log.action('%s: Test FIT with signed images' % sha_algo)
make_fit('sign-images-%s%s.its' % (sha_algo, padding))
run_bootm(sha_algo, 'unsigned images', 'dev-', True)
# Sign images with our dev keys
sign_fit(sha_algo, sign_options)
run_bootm(sha_algo, 'signed images', 'dev+', True)
# Create a fresh .dtb without the public keys
dtc('sandbox-u-boot.dts')
cons.log.action('%s: Test FIT with signed configuration' % sha_algo)
make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
run_bootm(sha_algo, 'unsigned config', '%s+ OK' % sha_algo, True)
# Sign images with our dev keys
sign_fit(sha_algo, sign_options)
run_bootm(sha_algo, 'signed config', 'dev+', True)
cons.log.action('%s: Check signed config on the host' % sha_algo)
util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', dtb])
# Make sure that U-Boot checks that the config is in the list of hashed
# nodes. If it isn't, a security bypass is possible.
with open(fit, 'rb') as fd:
root, strblock = vboot_forge.read_fdt(fd)
root, strblock = vboot_forge.manipulate(root, strblock)
with open(fit, 'w+b') as fd:
vboot_forge.write_fdt(root, strblock, fd)
util.run_and_log_expect_exception(
cons, [fit_check_sign, '-f', fit, '-k', dtb],
1, 'Failed to verify required signature')
run_bootm(sha_algo, 'forged config', 'Bad Data Hash', False)
# Create a new properly signed fit and replace header bytes
make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
sign_fit(sha_algo, sign_options)
bcfg = u_boot_console.config.buildconfig
max_size = int(bcfg.get('config_fit_signature_max_size', 0x10000000), 0)
existing_size = replace_fit_totalsize(max_size + 1)
run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash',
False)
cons.log.action('%s: Check overflowed FIT header totalsize' % sha_algo)
# Replace with existing header bytes
replace_fit_totalsize(existing_size)
run_bootm(sha_algo, 'signed config', 'dev+', True)
cons.log.action('%s: Check default FIT header totalsize' % sha_algo)
# Increment the first byte of the signature, which should cause failure
sig = util.run_and_log(cons, 'fdtget -t bx %s %s value' %
(fit, sig_node))
byte_list = sig.split()
byte = int(byte_list[0], 16)
byte_list[0] = '%x' % (byte + 1)
sig = ' '.join(byte_list)
util.run_and_log(cons, 'fdtput -t bx %s %s value %s' %
(fit, sig_node, sig))
run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash',
False)
cons.log.action('%s: Check bad config on the host' % sha_algo)
util.run_and_log_expect_exception(
cons, [fit_check_sign, '-f', fit, '-k', dtb],
1, 'Failed to verify required signature')
def test_required_key(sha_algo, padding, sign_options):
"""Test verified boot with the given hash algorithm.
This function tests if U-Boot rejects an image when a required key isn't
used to sign a FIT.
Args:
sha_algo: Either 'sha1' or 'sha256', to select the algorithm to use
padding: Either '' or '-pss', to select the padding to use for the
rsa signature algorithm.
sign_options: Options to mkimage when signing a fit image.
"""
# Compile our device tree files for kernel and U-Boot. These are
# regenerated here since mkimage will modify them (by adding a
# public key) below.
dtc('sandbox-kernel.dts')
dtc('sandbox-u-boot.dts')
cons.log.action('%s: Test FIT with configs images' % sha_algo)
# Build the FIT with prod key (keys required) and sign it. This puts the
# signature into sandbox-u-boot.dtb, marked 'required'
make_fit('sign-configs-%s%s-prod.its' % (sha_algo, padding))
sign_fit(sha_algo, sign_options)
# Build the FIT with dev key (keys NOT required). This adds the
# signature into sandbox-u-boot.dtb, NOT marked 'required'.
make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
sign_fit_norequire(sha_algo, sign_options)
# So now sandbox-u-boot.dtb two signatures, for the prod and dev keys.
# Only the prod key is set as 'required'. But FIT we just built has
# a dev signature only (sign_fit_norequire() overwrites the FIT).
# Try to boot the FIT with dev key. This FIT should not be accepted by
# U-Boot because the prod key is required.
run_bootm(sha_algo, 'required key', '', False)
# Build the FIT with dev key (keys required) and sign it. This puts the
# signature into sandbox-u-boot.dtb, marked 'required'.
make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
sign_fit(sha_algo, sign_options)
# Set the required-mode policy to "any".
# So now sandbox-u-boot.dtb two signatures, for the prod and dev keys.
# Both the dev and prod key are set as 'required'. But FIT we just built has
# a dev signature only (sign_fit() overwrites the FIT).
# Try to boot the FIT with dev key. This FIT should be accepted by
# U-Boot because the dev key is required and policy is "any" required key.
util.run_and_log(cons, 'fdtput -t s %s /signature required-mode any' %
(dtb))
run_bootm(sha_algo, 'multi required key', 'dev+', True)
# Set the required-mode policy to "all".
# So now sandbox-u-boot.dtb two signatures, for the prod and dev keys.
# Both the dev and prod key are set as 'required'. But FIT we just built has
# a dev signature only (sign_fit() overwrites the FIT).
# Try to boot the FIT with dev key. This FIT should not be accepted by
# U-Boot because the prod key is required and policy is "all" required key
util.run_and_log(cons, 'fdtput -t s %s /signature required-mode all' %
(dtb))
run_bootm(sha_algo, 'multi required key', '', False)
cons = u_boot_console
tmpdir = cons.config.result_dir + '/'
datadir = cons.config.source_dir + '/test/py/tests/vboot/'
fit = '%stest.fit' % tmpdir
mkimage = cons.config.build_dir + '/tools/mkimage'
fit_check_sign = cons.config.build_dir + '/tools/fit_check_sign'
dtc_args = '-I dts -O dtb -i %s' % tmpdir
dtb = '%ssandbox-u-boot.dtb' % tmpdir
sig_node = '/configurations/conf-1/signature'
create_rsa_pair('dev')
create_rsa_pair('prod')
# Create a number kernel image with zeroes
with open('%stest-kernel.bin' % tmpdir, 'w') as fd:
fd.write(500 * chr(0))
try:
# We need to use our own device tree file. Remember to restore it
# afterwards.
old_dtb = cons.config.dtb
cons.config.dtb = dtb
if required:
test_required_key(sha_algo, padding, sign_options)
else:
test_with_algo(sha_algo, padding, sign_options)
finally:
# Go back to the original U-Boot with the correct dtb.
cons.config.dtb = old_dtb
cons.restart_uboot()
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