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eb7690e81f
The pytest vboot does all his tests on fit without padding. We add the same tests on fit with padding. Reviewed-by: Simon Glass <sjg@chromium.org> Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
321 lines
12 KiB
Python
321 lines
12 KiB
Python
# SPDX-License-Identifier: GPL-2.0+
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# Copyright (c) 2016, Google Inc.
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#
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# U-Boot Verified Boot Test
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"""
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This tests verified boot in the following ways:
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For image verification:
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- Create FIT (unsigned) with mkimage
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- Check that verification shows that no keys are verified
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- Sign image
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- Check that verification shows that a key is now verified
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For configuration verification:
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- Corrupt signature and check for failure
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- Create FIT (with unsigned configuration) with mkimage
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- Check that image verification works
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- Sign the FIT and mark the key as 'required' for verification
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- Check that image verification works
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- Corrupt the signature
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- Check that image verification no-longer works
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Tests run with both SHA1 and SHA256 hashing.
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"""
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import struct
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import pytest
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import u_boot_utils as util
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import vboot_forge
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TESTDATA = [
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['sha1', '', None, False],
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['sha1', '', '-E -p 0x10000', False],
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['sha1', '-pss', None, False],
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['sha1', '-pss', '-E -p 0x10000', False],
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['sha256', '', None, False],
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['sha256', '', '-E -p 0x10000', False],
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['sha256', '-pss', None, False],
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['sha256', '-pss', '-E -p 0x10000', False],
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['sha256', '-pss', None, True],
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['sha256', '-pss', '-E -p 0x10000', True],
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]
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@pytest.mark.boardspec('sandbox')
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@pytest.mark.buildconfigspec('fit_signature')
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@pytest.mark.requiredtool('dtc')
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@pytest.mark.requiredtool('fdtget')
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@pytest.mark.requiredtool('fdtput')
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@pytest.mark.requiredtool('openssl')
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@pytest.mark.parametrize("sha_algo,padding,sign_options,required", TESTDATA)
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def test_vboot(u_boot_console, sha_algo, padding, sign_options, required):
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"""Test verified boot signing with mkimage and verification with 'bootm'.
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This works using sandbox only as it needs to update the device tree used
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by U-Boot to hold public keys from the signing process.
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The SHA1 and SHA256 tests are combined into a single test since the
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key-generation process is quite slow and we want to avoid doing it twice.
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"""
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def dtc(dts):
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"""Run the device tree compiler to compile a .dts file
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The output file will be the same as the input file but with a .dtb
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extension.
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Args:
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dts: Device tree file to compile.
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"""
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dtb = dts.replace('.dts', '.dtb')
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util.run_and_log(cons, 'dtc %s %s%s -O dtb '
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'-o %s%s' % (dtc_args, datadir, dts, tmpdir, dtb))
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def run_bootm(sha_algo, test_type, expect_string, boots):
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"""Run a 'bootm' command U-Boot.
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This always starts a fresh U-Boot instance since the device tree may
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contain a new public key.
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Args:
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test_type: A string identifying the test type.
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expect_string: A string which is expected in the output.
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sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
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use.
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boots: A boolean that is True if Linux should boot and False if
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we are expected to not boot
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"""
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cons.restart_uboot()
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with cons.log.section('Verified boot %s %s' % (sha_algo, test_type)):
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output = cons.run_command_list(
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['host load hostfs - 100 %stest.fit' % tmpdir,
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'fdt addr 100',
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'bootm 100'])
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assert expect_string in ''.join(output)
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if boots:
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assert 'sandbox: continuing, as we cannot run' in ''.join(output)
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else:
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assert('sandbox: continuing, as we cannot run'
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not in ''.join(output))
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def make_fit(its):
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"""Make a new FIT from the .its source file.
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This runs 'mkimage -f' to create a new FIT.
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Args:
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its: Filename containing .its source.
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"""
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util.run_and_log(cons, [mkimage, '-D', dtc_args, '-f',
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'%s%s' % (datadir, its), fit])
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def sign_fit(sha_algo, options):
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"""Sign the FIT
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Signs the FIT and writes the signature into it. It also writes the
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public key into the dtb.
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Args:
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sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
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use.
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options: Options to provide to mkimage.
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"""
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args = [mkimage, '-F', '-k', tmpdir, '-K', dtb, '-r', fit]
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if options:
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args += options.split(' ')
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cons.log.action('%s: Sign images' % sha_algo)
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util.run_and_log(cons, args)
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def replace_fit_totalsize(size):
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"""Replace FIT header's totalsize with something greater.
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The totalsize must be less than or equal to FIT_SIGNATURE_MAX_SIZE.
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If the size is greater, the signature verification should return false.
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Args:
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size: The new totalsize of the header
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Returns:
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prev_size: The previous totalsize read from the header
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"""
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total_size = 0
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with open(fit, 'r+b') as handle:
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handle.seek(4)
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total_size = handle.read(4)
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handle.seek(4)
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handle.write(struct.pack(">I", size))
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return struct.unpack(">I", total_size)[0]
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def create_rsa_pair(name):
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"""Generate a new RSA key paid and certificate
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Args:
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name: Name of of the key (e.g. 'dev')
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"""
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public_exponent = 65537
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util.run_and_log(cons, 'openssl genpkey -algorithm RSA -out %s%s.key '
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'-pkeyopt rsa_keygen_bits:2048 '
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'-pkeyopt rsa_keygen_pubexp:%d' %
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(tmpdir, name, public_exponent))
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# Create a certificate containing the public key
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util.run_and_log(cons, 'openssl req -batch -new -x509 -key %s%s.key '
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'-out %s%s.crt' % (tmpdir, name, tmpdir, name))
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def test_with_algo(sha_algo, padding, sign_options):
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"""Test verified boot with the given hash algorithm.
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This is the main part of the test code. The same procedure is followed
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for both hashing algorithms.
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Args:
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sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
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use.
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padding: Either '' or '-pss', to select the padding to use for the
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rsa signature algorithm.
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sign_options: Options to mkimage when signing a fit image.
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"""
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# Compile our device tree files for kernel and U-Boot. These are
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# regenerated here since mkimage will modify them (by adding a
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# public key) below.
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dtc('sandbox-kernel.dts')
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dtc('sandbox-u-boot.dts')
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# Build the FIT, but don't sign anything yet
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cons.log.action('%s: Test FIT with signed images' % sha_algo)
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make_fit('sign-images-%s%s.its' % (sha_algo, padding))
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run_bootm(sha_algo, 'unsigned images', 'dev-', True)
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# Sign images with our dev keys
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sign_fit(sha_algo, sign_options)
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run_bootm(sha_algo, 'signed images', 'dev+', True)
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# Create a fresh .dtb without the public keys
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dtc('sandbox-u-boot.dts')
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cons.log.action('%s: Test FIT with signed configuration' % sha_algo)
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make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
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run_bootm(sha_algo, 'unsigned config', '%s+ OK' % sha_algo, True)
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# Sign images with our dev keys
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sign_fit(sha_algo, sign_options)
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run_bootm(sha_algo, 'signed config', 'dev+', True)
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cons.log.action('%s: Check signed config on the host' % sha_algo)
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util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', dtb])
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# Make sure that U-Boot checks that the config is in the list of hashed
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# nodes. If it isn't, a security bypass is possible.
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with open(fit, 'rb') as fd:
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root, strblock = vboot_forge.read_fdt(fd)
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root, strblock = vboot_forge.manipulate(root, strblock)
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with open(fit, 'w+b') as fd:
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vboot_forge.write_fdt(root, strblock, fd)
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util.run_and_log_expect_exception(
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cons, [fit_check_sign, '-f', fit, '-k', dtb],
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1, 'Failed to verify required signature')
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run_bootm(sha_algo, 'forged config', 'Bad Data Hash', False)
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# Create a new properly signed fit and replace header bytes
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make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
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sign_fit(sha_algo, sign_options)
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bcfg = u_boot_console.config.buildconfig
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max_size = int(bcfg.get('config_fit_signature_max_size', 0x10000000), 0)
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existing_size = replace_fit_totalsize(max_size + 1)
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run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash',
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False)
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cons.log.action('%s: Check overflowed FIT header totalsize' % sha_algo)
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# Replace with existing header bytes
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replace_fit_totalsize(existing_size)
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run_bootm(sha_algo, 'signed config', 'dev+', True)
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cons.log.action('%s: Check default FIT header totalsize' % sha_algo)
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# Increment the first byte of the signature, which should cause failure
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sig = util.run_and_log(cons, 'fdtget -t bx %s %s value' %
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(fit, sig_node))
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byte_list = sig.split()
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byte = int(byte_list[0], 16)
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byte_list[0] = '%x' % (byte + 1)
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sig = ' '.join(byte_list)
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util.run_and_log(cons, 'fdtput -t bx %s %s value %s' %
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(fit, sig_node, sig))
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run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash',
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False)
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cons.log.action('%s: Check bad config on the host' % sha_algo)
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util.run_and_log_expect_exception(
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cons, [fit_check_sign, '-f', fit, '-k', dtb],
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1, 'Failed to verify required signature')
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def test_required_key(sha_algo, padding, sign_options):
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"""Test verified boot with the given hash algorithm.
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This function tests if U-Boot rejects an image when a required key isn't
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used to sign a FIT.
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Args:
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sha_algo: Either 'sha1' or 'sha256', to select the algorithm to use
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padding: Either '' or '-pss', to select the padding to use for the
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rsa signature algorithm.
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sign_options: Options to mkimage when signing a fit image.
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"""
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# Compile our device tree files for kernel and U-Boot. These are
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# regenerated here since mkimage will modify them (by adding a
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# public key) below.
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dtc('sandbox-kernel.dts')
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dtc('sandbox-u-boot.dts')
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cons.log.action('%s: Test FIT with configs images' % sha_algo)
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# Build the FIT with prod key (keys required) and sign it. This puts the
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# signature into sandbox-u-boot.dtb, marked 'required'
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make_fit('sign-configs-%s%s-prod.its' % (sha_algo, padding))
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sign_fit(sha_algo, sign_options)
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# Build the FIT with dev key (keys NOT required). This adds the
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# signature into sandbox-u-boot.dtb, NOT marked 'required'.
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make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
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sign_fit(sha_algo, sign_options)
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# So now sandbox-u-boot.dtb two signatures, for the prod and dev keys.
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# Only the prod key is set as 'required'. But FIT we just built has
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# a dev signature only (sign_fit() overwrites the FIT).
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# Try to boot the FIT with dev key. This FIT should not be accepted by
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# U-Boot because the prod key is required.
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run_bootm(sha_algo, 'required key', '', False)
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cons = u_boot_console
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tmpdir = cons.config.result_dir + '/'
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datadir = cons.config.source_dir + '/test/py/tests/vboot/'
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fit = '%stest.fit' % tmpdir
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mkimage = cons.config.build_dir + '/tools/mkimage'
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fit_check_sign = cons.config.build_dir + '/tools/fit_check_sign'
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dtc_args = '-I dts -O dtb -i %s' % tmpdir
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dtb = '%ssandbox-u-boot.dtb' % tmpdir
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sig_node = '/configurations/conf-1/signature'
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create_rsa_pair('dev')
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create_rsa_pair('prod')
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# Create a number kernel image with zeroes
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with open('%stest-kernel.bin' % tmpdir, 'w') as fd:
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fd.write(500 * chr(0))
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try:
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# We need to use our own device tree file. Remember to restore it
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# afterwards.
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old_dtb = cons.config.dtb
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cons.config.dtb = dtb
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if required:
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test_required_key(sha_algo, padding, sign_options)
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else:
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test_with_algo(sha_algo, padding, sign_options)
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finally:
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# Go back to the original U-Boot with the correct dtb.
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cons.config.dtb = old_dtb
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cons.restart_uboot()
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