Googler | 25e92cf | 2023-12-13 10:05:01 +0000 | [diff] [blame^] | 1 | # SPDX-License-Identifier: GPL-2.0+ |
| 2 | # Copyright (c) 2016, Google Inc. |
| 3 | # |
| 4 | # U-Boot Verified Boot Test |
| 5 | |
| 6 | """ |
| 7 | This tests verified boot in the following ways: |
| 8 | |
| 9 | For image verification: |
| 10 | - Create FIT (unsigned) with mkimage |
| 11 | - Check that verification shows that no keys are verified |
| 12 | - Sign image |
| 13 | - Check that verification shows that a key is now verified |
| 14 | |
| 15 | For configuration verification: |
| 16 | - Corrupt signature and check for failure |
| 17 | - Create FIT (with unsigned configuration) with mkimage |
| 18 | - Check that image verification works |
| 19 | - Sign the FIT and mark the key as 'required' for verification |
| 20 | - Check that image verification works |
| 21 | - Corrupt the signature |
| 22 | - Check that image verification no-longer works |
| 23 | |
| 24 | Tests run with both SHA1 and SHA256 hashing. |
| 25 | """ |
| 26 | |
| 27 | |
| 28 | import shutil |
| 29 | import pytest |
| 30 | import sys |
| 31 | import struct |
| 32 | import u_boot_utils as util |
| 33 | import vboot_evil |
| 34 | |
| 35 | # Only run the full suite on a few combinations, since it doesn't add any more |
| 36 | # test coverage. |
| 37 | TESTDATA = [ |
| 38 | ['sha1', '', None, False, True], |
| 39 | ['sha1', '', '-E -p 0x10000', False, False], |
| 40 | ['sha1', '-pss', None, False, False], |
| 41 | ['sha1', '-pss', '-E -p 0x10000', False, False], |
| 42 | ['sha256', '', None, False, False], |
| 43 | ['sha256', '', '-E -p 0x10000', False, False], |
| 44 | ['sha256', '-pss', None, False, False], |
| 45 | ['sha256', '-pss', '-E -p 0x10000', False, False], |
| 46 | ['sha256', '-pss', None, True, False], |
| 47 | ['sha256', '-pss', '-E -p 0x10000', True, True], |
| 48 | ] |
| 49 | |
| 50 | @pytest.mark.boardspec('sandbox') |
| 51 | @pytest.mark.buildconfigspec('fit_signature') |
| 52 | @pytest.mark.requiredtool('dtc') |
| 53 | @pytest.mark.requiredtool('fdtget') |
| 54 | @pytest.mark.requiredtool('fdtput') |
| 55 | @pytest.mark.requiredtool('openssl') |
| 56 | def test_vboot(u_boot_console): |
| 57 | """Test verified boot signing with mkimage and verification with 'bootm'. |
| 58 | |
| 59 | This works using sandbox only as it needs to update the device tree used |
| 60 | by U-Boot to hold public keys from the signing process. |
| 61 | |
| 62 | The SHA1 and SHA256 tests are combined into a single test since the |
| 63 | key-generation process is quite slow and we want to avoid doing it twice. |
| 64 | """ |
| 65 | def dtc(dts): |
| 66 | """Run the device tree compiler to compile a .dts file |
| 67 | |
| 68 | The output file will be the same as the input file but with a .dtb |
| 69 | extension. |
| 70 | |
| 71 | Args: |
| 72 | dts: Device tree file to compile. |
| 73 | """ |
| 74 | dtb = dts.replace('.dts', '.dtb') |
| 75 | util.run_and_log(cons, 'dtc %s %s%s -O dtb ' |
| 76 | '-o %s%s' % (dtc_args, datadir, dts, tmpdir, dtb)) |
| 77 | |
| 78 | def run_bootm(sha_algo, test_type, expect_string, boots, fit=None): |
| 79 | """Run a 'bootm' command U-Boot. |
| 80 | |
| 81 | This always starts a fresh U-Boot instance since the device tree may |
| 82 | contain a new public key. |
| 83 | |
| 84 | Args: |
| 85 | test_type: A string identifying the test type. |
| 86 | expect_string: A string which is expected in the output. |
| 87 | sha_algo: Either 'sha1' or 'sha256', to select the algorithm to |
| 88 | use. |
| 89 | boots: A boolean that is True if Linux should boot and False if |
| 90 | we are expected to not boot |
| 91 | """ |
| 92 | cons.restart_uboot() |
| 93 | with cons.log.section('Verified boot %s %s' % (sha_algo, test_type)): |
| 94 | output = cons.run_command_list( |
| 95 | ['host load hostfs - 100 %stest.fit' % tmpdir, |
| 96 | 'fdt addr 100', |
| 97 | 'bootm 100']) |
| 98 | assert(expect_string in ''.join(output)) |
| 99 | if boots: |
| 100 | assert('sandbox: continuing, as we cannot run' in ''.join(output)) |
| 101 | |
| 102 | def make_fit(its): |
| 103 | """Make a new FIT from the .its source file. |
| 104 | |
| 105 | This runs 'mkimage -f' to create a new FIT. |
| 106 | |
| 107 | Args: |
| 108 | its: Filename containing .its source. |
| 109 | """ |
| 110 | util.run_and_log(cons, [mkimage, '-D', dtc_args, '-f', |
| 111 | '%s%s' % (datadir, its), fit]) |
| 112 | |
| 113 | def sign_fit(sha_algo): |
| 114 | """Sign the FIT |
| 115 | |
| 116 | Signs the FIT and writes the signature into it. It also writes the |
| 117 | public key into the dtb. |
| 118 | |
| 119 | Args: |
| 120 | sha_algo: Either 'sha1' or 'sha256', to select the algorithm to |
| 121 | use. |
| 122 | """ |
| 123 | cons.log.action('%s: Sign images' % sha_algo) |
| 124 | util.run_and_log(cons, [mkimage, '-F', '-k', tmpdir, '-K', dtb, |
| 125 | '-r', fit]) |
| 126 | |
| 127 | def replace_fit_totalsize(size): |
| 128 | """Replace FIT header's totalsize with something greater. |
| 129 | |
| 130 | The totalsize must be less than or equal to FIT_SIGNATURE_MAX_SIZE. |
| 131 | If the size is greater, the signature verification should return false. |
| 132 | |
| 133 | Args: |
| 134 | size: The new totalsize of the header |
| 135 | |
| 136 | Returns: |
| 137 | prev_size: The previous totalsize read from the header |
| 138 | """ |
| 139 | total_size = 0 |
| 140 | with open(fit, 'r+b') as handle: |
| 141 | handle.seek(4) |
| 142 | total_size = handle.read(4) |
| 143 | handle.seek(4) |
| 144 | handle.write(struct.pack(">I", size)) |
| 145 | return struct.unpack(">I", total_size)[0] |
| 146 | |
| 147 | def test_with_algo(sha_algo, padding): |
| 148 | """Test verified boot with the given hash algorithm. |
| 149 | |
| 150 | This is the main part of the test code. The same procedure is followed |
| 151 | for both hashing algorithms. |
| 152 | |
| 153 | Args: |
| 154 | sha_algo: Either 'sha1' or 'sha256', to select the algorithm to |
| 155 | use. |
| 156 | """ |
| 157 | # Compile our device tree files for kernel and U-Boot. These are |
| 158 | # regenerated here since mkimage will modify them (by adding a |
| 159 | # public key) below. |
| 160 | dtc('sandbox-kernel.dts') |
| 161 | dtc('sandbox-u-boot.dts') |
| 162 | |
| 163 | # Build the FIT, but don't sign anything yet |
| 164 | cons.log.action('%s: Test FIT with signed images' % sha_algo) |
| 165 | make_fit('sign-images-%s%s.its' % (sha_algo , padding)) |
| 166 | run_bootm(sha_algo, 'unsigned images', 'dev-', True) |
| 167 | |
| 168 | # Sign images with our dev keys |
| 169 | sign_fit(sha_algo) |
| 170 | run_bootm(sha_algo, 'signed images', 'dev+', True) |
| 171 | |
| 172 | # Create a fresh .dtb without the public keys |
| 173 | dtc('sandbox-u-boot.dts') |
| 174 | |
| 175 | cons.log.action('%s: Test FIT with signed configuration' % sha_algo) |
| 176 | make_fit('sign-configs-%s%s.its' % (sha_algo , padding)) |
| 177 | run_bootm(sha_algo, 'unsigned config', '%s+ OK' % sha_algo, True) |
| 178 | |
| 179 | # Sign images with our dev keys |
| 180 | sign_fit(sha_algo) |
| 181 | run_bootm(sha_algo, 'signed config', 'dev+', True) |
| 182 | |
| 183 | cons.log.action('%s: Check signed config on the host' % sha_algo) |
| 184 | |
| 185 | util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', tmpdir, |
| 186 | '-k', dtb]) |
| 187 | |
| 188 | # Replace header bytes |
| 189 | bcfg = u_boot_console.config.buildconfig |
| 190 | max_size = int(bcfg.get('config_fit_signature_max_size', 0x10000000), 0) |
| 191 | existing_size = replace_fit_totalsize(max_size + 1) |
| 192 | run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash', False) |
| 193 | cons.log.action('%s: Check overflowed FIT header totalsize' % sha_algo) |
| 194 | |
| 195 | # Replace with existing header bytes |
| 196 | replace_fit_totalsize(existing_size) |
| 197 | run_bootm(sha_algo, 'signed config', 'dev+', True) |
| 198 | cons.log.action('%s: Check default FIT header totalsize' % sha_algo) |
| 199 | |
| 200 | # Increment the first byte of the signature, which should cause failure |
| 201 | sig = util.run_and_log(cons, 'fdtget -t bx %s %s value' % |
| 202 | (fit, sig_node)) |
| 203 | byte_list = sig.split() |
| 204 | byte = int(byte_list[0], 16) |
| 205 | byte_list[0] = '%x' % (byte + 1) |
| 206 | sig = ' '.join(byte_list) |
| 207 | util.run_and_log(cons, 'fdtput -t bx %s %s value %s' % |
| 208 | (fit, sig_node, sig)) |
| 209 | |
| 210 | run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash', False) |
| 211 | |
| 212 | cons.log.action('%s: Check bad config on the host' % sha_algo) |
| 213 | util.run_and_log_expect_exception(cons, [fit_check_sign, '-f', fit, |
| 214 | '-k', dtb], 1, 'Failed to verify required signature') |
| 215 | |
| 216 | cons = u_boot_console |
| 217 | tmpdir = cons.config.result_dir + '/' |
| 218 | tmp = tmpdir + 'vboot.tmp' |
| 219 | datadir = cons.config.source_dir + '/test/py/tests/vboot/' |
| 220 | fit = '%stest.fit' % tmpdir |
| 221 | mkimage = cons.config.build_dir + '/tools/mkimage' |
| 222 | fit_check_sign = cons.config.build_dir + '/tools/fit_check_sign' |
| 223 | dtc_args = '-I dts -O dtb -i %s' % tmpdir |
| 224 | dtb = '%ssandbox-u-boot.dtb' % tmpdir |
| 225 | sig_node = '/configurations/conf-1/signature' |
| 226 | |
| 227 | # Create an RSA key pair |
| 228 | public_exponent = 65537 |
| 229 | util.run_and_log(cons, 'openssl genpkey -algorithm RSA -out %sdev.key ' |
| 230 | '-pkeyopt rsa_keygen_bits:2048 ' |
| 231 | '-pkeyopt rsa_keygen_pubexp:%d' % |
| 232 | (tmpdir, public_exponent)) |
| 233 | |
| 234 | # Create a certificate containing the public key |
| 235 | util.run_and_log(cons, 'openssl req -batch -new -x509 -key %sdev.key -out ' |
| 236 | '%sdev.crt' % (tmpdir, tmpdir)) |
| 237 | |
| 238 | # Create a number kernel image with zeroes |
| 239 | with open('%stest-kernel.bin' % tmpdir, 'w') as fd: |
| 240 | fd.write(5000 * chr(0)) |
| 241 | |
| 242 | try: |
| 243 | # We need to use our own device tree file. Remember to restore it |
| 244 | # afterwards. |
| 245 | old_dtb = cons.config.dtb |
| 246 | cons.config.dtb = dtb |
| 247 | test_with_algo('sha1','') |
| 248 | test_with_algo('sha1','-pss') |
| 249 | test_with_algo('sha256','') |
| 250 | test_with_algo('sha256','-pss') |
| 251 | finally: |
| 252 | # Go back to the original U-Boot with the correct dtb. |
| 253 | cons.config.dtb = old_dtb |
| 254 | cons.restart_uboot() |