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.run_and_log(cons, 'dtc %s %s%s -O dtb '
  54                          '-o %s%s' % (dtc_args, datadir, dts, tmpdir, dtb))
  55
  56     def run_bootm(sha_algo, test_type, expect_string, boots):
  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             sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
  66                     use.
  67             boots: A boolean that is True if Linux should boot and False if
  68                     we are expected to not boot
  69         """
  70         cons.restart_uboot()
  71         with cons.log.section('Verified boot %s %s' % (sha_algo, test_type)):
  72             output = cons.run_command_list(
  73                 ['sb load hostfs - 100 %stest.fit' % tmpdir,
  74                 'fdt addr 100',
  75                 'bootm 100'])
  76         assert(expect_string in ''.join(output))
  77         if boots:
  78             assert('sandbox: continuing, as we cannot run' in ''.join(output))
  79
  80     def make_fit(its):
  81         """Make a new FIT from the .its source file.
  82
  83         This runs 'mkimage -f' to create a new FIT.
  84
  85         Args:
  86             its: Filename containing .its source.
  87         """
  88         util.run_and_log(cons, [mkimage, '-D', dtc_args, '-f',
  89                                 '%s%s' % (datadir, its), fit])
  90
  91     def sign_fit(sha_algo):
  92         """Sign the FIT
  93
  94         Signs the FIT and writes the signature into it. It also writes the
  95         public key into the dtb.
  96
  97         Args:
  98             sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
  99                     use.
 100         """
 101         cons.log.action('%s: Sign images' % sha_algo)
 102         util.run_and_log(cons, [mkimage, '-F', '-k', tmpdir, '-K', dtb,
 103                                 '-r', fit])
 104
 105     def test_with_algo(sha_algo):
 106         """Test verified boot with the given hash algorithm.
 107
 108         This is the main part of the test code. The same procedure is followed
 109         for both hashing algorithms.
 110
 111         Args:
 112             sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
 113                     use.
 114         """
 115         # Compile our device tree files for kernel and U-Boot. These are
 116         # regenerated here since mkimage will modify them (by adding a
 117         # public key) below.
 118         dtc('sandbox-kernel.dts')
 119         dtc('sandbox-u-boot.dts')
 120
 121         # Build the FIT, but don't sign anything yet
 122         cons.log.action('%s: Test FIT with signed images' % sha_algo)
 123         make_fit('sign-images-%s.its' % sha_algo)
 124         run_bootm(sha_algo, 'unsigned images', 'dev-', True)
 125
 126         # Sign images with our dev keys
 127         sign_fit(sha_algo)
 128         run_bootm(sha_algo, 'signed images', 'dev+', True)
 129
 130         # Create a fresh .dtb without the public keys
 131         dtc('sandbox-u-boot.dts')
 132
 133         cons.log.action('%s: Test FIT with signed configuration' % sha_algo)
 134         make_fit('sign-configs-%s.its' % sha_algo)
 135         run_bootm(sha_algo, 'unsigned config', '%s+ OK' % sha_algo, True)
 136
 137         # Sign images with our dev keys
 138         sign_fit(sha_algo)
 139         run_bootm(sha_algo, 'signed config', 'dev+', True)
 140
 141         cons.log.action('%s: Check signed config on the host' % sha_algo)
 142
 143         util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', tmpdir,
 144                                 '-k', dtb])
 145
 146         # Increment the first byte of the signature, which should cause failure
 147         sig = util.run_and_log(cons, 'fdtget -t bx %s %s value' %
 148                                (fit, sig_node))
 149         byte_list = sig.split()
 150         byte = int(byte_list[0], 16)
 151         byte_list[0] = '%x' % (byte + 1)
 152         sig = ' '.join(byte_list)
 153         util.run_and_log(cons, 'fdtput -t bx %s %s value %s' %
 154                          (fit, sig_node, sig))
 155
 156         run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash', False)
 157
 158         cons.log.action('%s: Check bad config on the host' % sha_algo)
 159         util.run_and_log_expect_exception(cons, [fit_check_sign, '-f', fit,
 160                 '-k', dtb], 1, 'Failed to verify required signature')
 161
 162     cons = u_boot_console
 163     tmpdir = cons.config.result_dir + '/'
 164     tmp = tmpdir + 'vboot.tmp'
 165     datadir = cons.config.source_dir + '/test/py/tests/vboot/'
 166     fit = '%stest.fit' % tmpdir
 167     mkimage = cons.config.build_dir + '/tools/mkimage'
 168     fit_check_sign = cons.config.build_dir + '/tools/fit_check_sign'
 169     dtc_args = '-I dts -O dtb -i %s' % tmpdir
 170     dtb = '%ssandbox-u-boot.dtb' % tmpdir
 171     sig_node = '/configurations/conf@1/signature@1'
 172
 173     # Create an RSA key pair
 174     public_exponent = 65537
 175     util.run_and_log(cons, 'openssl genpkey -algorithm RSA -out %sdev.key '
 176                      '-pkeyopt rsa_keygen_bits:2048 '
 177                      '-pkeyopt rsa_keygen_pubexp:%d '
 178                      '2>/dev/null'  % (tmpdir, public_exponent))
 179
 180     # Create a certificate containing the public key
 181     util.run_and_log(cons, 'openssl req -batch -new -x509 -key %sdev.key -out '
 182                      '%sdev.crt' % (tmpdir, tmpdir))
 183
 184     # Create a number kernel image with zeroes
 185     with open('%stest-kernel.bin' % tmpdir, 'w') as fd:
 186         fd.write(5000 * chr(0))
 187
 188     try:
 189         # We need to use our own device tree file. Remember to restore it
 190         # afterwards.
 191         old_dtb = cons.config.dtb
 192         cons.config.dtb = dtb
 193         test_with_algo('sha1')
 194         test_with_algo('sha256')
 195     finally:
 196         # Go back to the original U-Boot with the correct dtb.
 197         cons.config.dtb = old_dtb
 198         cons.restart_uboot()