test/py/tests/test_vboot.py

   1 # Copyright (c) 2016, Google Inc.
   2 #
   3 # SPDX-License-Identifier:      GPL-2.0+
   4 #
   5 # U-Boot Verified Boot Test
   6
   7 """
   8 This tests verified boot in the following ways:
   9
  10 For image verification:
  11 - Create FIT (unsigned) with mkimage
  12 - Check that verification shows that no keys are verified
  13 - Sign image
  14 - Check that verification shows that a key is now verified
  15
  16 For configuration verification:
  17 - Corrupt signature and check for failure
  18 - Create FIT (with unsigned configuration) with mkimage
  19 - Check that image verification works
  20 - Sign the FIT and mark the key as 'required' for verification
  21 - Check that image verification works
  22 - Corrupt the signature
  23 - Check that image verification no-longer works
  24
  25 Tests run with both SHA1 and SHA256 hashing.
  26 """
  27
  28 import pytest
  29 import sys
  30 import u_boot_utils as util
  31
  32 @pytest.mark.boardspec('sandbox')
  33 @pytest.mark.buildconfigspec('fit_signature')
  34 def test_vboot(u_boot_console):
  35     """Test verified boot signing with mkimage and verification with 'bootm'.
  36
  37     This works using sandbox only as it needs to update the device tree used
  38     by U-Boot to hold public keys from the signing process.
  39
  40     The SHA1 and SHA256 tests are combined into a single test since the
  41     key-generation process is quite slow and we want to avoid doing it twice.
  42     """
  43     def dtc(dts):
  44         """Run the device tree compiler to compile a .dts file
  45
  46         The output file will be the same as the input file but with a .dtb
  47         extension.
  48
  49         Args:
  50             dts: Device tree file to compile.
  51         """
  52         dtb = dts.replace('.dts', '.dtb')
  53         util.cmd(cons, 'dtc %s %s%s -O dtb '
  54                        '-o %s%s' % (dtc_args, datadir, dts, tmpdir, dtb))
  55
  56     def run_bootm(test_type, expect_string):
  57         """Run a 'bootm' command U-Boot.
  58
  59         This always starts a fresh U-Boot instance since the device tree may
  60         contain a new public key.
  61
  62         Args:
  63             test_type: A string identifying the test type
  64             expect_string: A string which is expected in the output
  65         """
  66         cons.cleanup_spawn()
  67         cons.ensure_spawned()
  68         cons.log.action('%s: Test Verified Boot Run: %s' % (algo, test_type))
  69         output = cons.run_command_list(
  70             ['sb load hostfs - 100 %stest.fit' % tmpdir,
  71              'fdt addr 100',
  72              'bootm 100'])
  73         assert(expect_string in output)
  74
  75     def make_fit(its):
  76         """Make a new FIT from the .its source file.
  77
  78         This runs 'mkimage -f' to create a new FIT.
  79
  80         Args:
  81             its: Filename containing .its source.
  82         """
  83         util.run_and_log(cons, [mkimage, '-D', dtc_args, '-f',
  84                                 '%s%s' % (datadir, its), fit])
  85
  86     def sign_fit():
  87         """Sign the FIT
  88
  89         Signs the FIT and writes the signature into it. It also writes the
  90         public key into the dtb.
  91         """
  92         cons.log.action('%s: Sign images' % algo)
  93         util.run_and_log(cons, [mkimage, '-F', '-k', tmpdir, '-K', dtb,
  94                                 '-r', fit])
  95
  96     def test_with_algo(sha):
  97         """Test verified boot with the given hash algorithm.
  98
  99         This is the main part of the test code. The same procedure is followed
 100         for both hashing algorithms.
 101
 102         Args:
 103             sha: Either 'sha1' or 'sha256', to select the algorithm to use
 104         """
 105         global algo
 106
 107         algo = sha
 108
 109         # Compile our device tree files for kernel and U-Boot. These are
 110         # regenerated here since mkimage will modify them (by adding a
 111         # public key) below.
 112         dtc('sandbox-kernel.dts')
 113         dtc('sandbox-u-boot.dts')
 114
 115         # Build the FIT, but don't sign anything yet
 116         cons.log.action('%s: Test FIT with signed images' % algo)
 117         make_fit('sign-images-%s.its' % algo)
 118         run_bootm('unsigned images', 'dev-')
 119
 120         # Sign images with our dev keys
 121         sign_fit()
 122         run_bootm('signed images', 'dev+')
 123
 124         # Create a fresh .dtb without the public keys
 125         dtc('sandbox-u-boot.dts')
 126
 127         cons.log.action('%s: Test FIT with signed configuration' % algo)
 128         make_fit('sign-configs-%s.its' % algo)
 129         run_bootm('unsigned config', '%s+ OK' % algo)
 130
 131         # Sign images with our dev keys
 132         sign_fit()
 133         run_bootm('signed config', 'dev+')
 134
 135         cons.log.action('%s: Check signed config on the host' % algo)
 136
 137         util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', tmpdir,
 138                                 '-k', dtb])
 139
 140         # Increment the first byte of the signature, which should cause failure
 141         sig = util.cmd(cons, 'fdtget -t bx %s %s value' % (fit, sig_node))
 142         byte_list = sig.split()
 143         byte = int(byte_list[0], 16)
 144         byte_list[0] = '%x' % (byte + 1)
 145         sig = ' '.join(byte_list)
 146         util.cmd(cons, 'fdtput -t bx %s %s value %s' % (fit, sig_node, sig))
 147
 148         run_bootm('Signed config with bad hash', 'Bad Data Hash')
 149
 150         cons.log.action('%s: Check bad config on the host' % algo)
 151         util.run_and_log_expect_exception(cons, [fit_check_sign, '-f', fit,
 152                 '-k', dtb], 1, 'Failed to verify required signature')
 153
 154     cons = u_boot_console
 155     tmpdir = cons.config.result_dir + '/'
 156     tmp = tmpdir + 'vboot.tmp'
 157     datadir = cons.config.source_dir + '/test/py/tests/vboot/'
 158     fit = '%stest.fit' % tmpdir
 159     mkimage = cons.config.build_dir + '/tools/mkimage'
 160     fit_check_sign = cons.config.build_dir + '/tools/fit_check_sign'
 161     dtc_args = '-I dts -O dtb -i %s' % tmpdir
 162     dtb = '%ssandbox-u-boot.dtb' % tmpdir
 163     sig_node = '/configurations/conf@1/signature@1'
 164
 165     # Create an RSA key pair
 166     public_exponent = 65537
 167     util.cmd(cons, 'openssl genpkey -algorithm RSA -out %sdev.key '
 168                    '-pkeyopt rsa_keygen_bits:2048 '
 169                    '-pkeyopt rsa_keygen_pubexp:%d '
 170                    '2>/dev/null'  % (tmpdir, public_exponent))
 171
 172     # Create a certificate containing the public key
 173     util.cmd(cons, 'openssl req -batch -new -x509 -key %sdev.key -out '
 174                    '%sdev.crt' % (tmpdir, tmpdir))
 175
 176     # Create a number kernel image with zeroes
 177     with open('%stest-kernel.bin' % tmpdir, 'w') as fd:
 178         fd.write(5000 * chr(0))
 179
 180     try:
 181         # We need to use our own device tree file. Remember to restore it
 182         # afterwards.
 183         old_dtb = cons.config.dtb
 184         cons.config.dtb = dtb
 185         test_with_algo('sha1')
 186         test_with_algo('sha256')
 187     finally:
 188         cons.config.dtb = old_dtb