237 lines
8.6 KiB
Python
237 lines
8.6 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 pytest
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import sys
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import struct
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import u_boot_utils as util
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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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def test_vboot(u_boot_console):
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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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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):
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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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"""
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cons.log.action('%s: Sign images' % sha_algo)
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util.run_and_log(cons, [mkimage, '-F', '-k', tmpdir, '-K', dtb,
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'-r', fit])
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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 test_with_algo(sha_algo, padding):
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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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"""
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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)
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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)
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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', tmpdir,
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'-k', dtb])
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# Replace header bytes
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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', 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', 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(cons, [fit_check_sign, '-f', fit,
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'-k', dtb], 1, 'Failed to verify required signature')
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cons = u_boot_console
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tmpdir = cons.config.result_dir + '/'
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tmp = tmpdir + 'vboot.tmp'
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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 an RSA key pair
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public_exponent = 65537
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util.run_and_log(cons, 'openssl genpkey -algorithm RSA -out %sdev.key '
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'-pkeyopt rsa_keygen_bits:2048 '
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'-pkeyopt rsa_keygen_pubexp:%d' %
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(tmpdir, 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 %sdev.key -out '
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'%sdev.crt' % (tmpdir, tmpdir))
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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(5000 * 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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test_with_algo('sha1','')
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test_with_algo('sha1','-pss')
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test_with_algo('sha256','')
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test_with_algo('sha256','-pss')
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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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