1 # SPDX-License-Identifier: GPL-2.0+
2 # Copyright (c) 2016, Google Inc.
4 # U-Boot Verified Boot Test
7 This tests verified boot in the following ways:
9 For image verification:
10 - Create FIT (unsigned) with mkimage
11 - Check that verification shows that no keys are verified
13 - Check that verification shows that a key is now verified
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
24 Tests run with both SHA1 and SHA256 hashing.
29 import u_boot_utils as util
34 ['sha1', '-pss', False],
35 ['sha256', '', False],
36 ['sha256', '-pss', False],
37 ['sha256', '-pss', True],
40 @pytest.mark.boardspec('sandbox')
41 @pytest.mark.buildconfigspec('fit_signature')
42 @pytest.mark.requiredtool('dtc')
43 @pytest.mark.requiredtool('fdtget')
44 @pytest.mark.requiredtool('fdtput')
45 @pytest.mark.requiredtool('openssl')
46 @pytest.mark.parametrize("sha_algo,padding,required", TESTDATA)
47 def test_vboot(u_boot_console, sha_algo, padding, required):
48 """Test verified boot signing with mkimage and verification with 'bootm'.
50 This works using sandbox only as it needs to update the device tree used
51 by U-Boot to hold public keys from the signing process.
53 The SHA1 and SHA256 tests are combined into a single test since the
54 key-generation process is quite slow and we want to avoid doing it twice.
57 """Run the device tree compiler to compile a .dts file
59 The output file will be the same as the input file but with a .dtb
63 dts: Device tree file to compile.
65 dtb = dts.replace('.dts', '.dtb')
66 util.run_and_log(cons, 'dtc %s %s%s -O dtb '
67 '-o %s%s' % (dtc_args, datadir, dts, tmpdir, dtb))
69 def run_bootm(sha_algo, test_type, expect_string, boots):
70 """Run a 'bootm' command U-Boot.
72 This always starts a fresh U-Boot instance since the device tree may
73 contain a new public key.
76 test_type: A string identifying the test type.
77 expect_string: A string which is expected in the output.
78 sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
80 boots: A boolean that is True if Linux should boot and False if
81 we are expected to not boot
84 with cons.log.section('Verified boot %s %s' % (sha_algo, test_type)):
85 output = cons.run_command_list(
86 ['host load hostfs - 100 %stest.fit' % tmpdir,
89 assert expect_string in ''.join(output)
91 assert 'sandbox: continuing, as we cannot run' in ''.join(output)
93 assert('sandbox: continuing, as we cannot run'
94 not in ''.join(output))
97 """Make a new FIT from the .its source file.
99 This runs 'mkimage -f' to create a new FIT.
102 its: Filename containing .its source.
104 util.run_and_log(cons, [mkimage, '-D', dtc_args, '-f',
105 '%s%s' % (datadir, its), fit])
107 def sign_fit(sha_algo):
110 Signs the FIT and writes the signature into it. It also writes the
111 public key into the dtb.
114 sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
117 cons.log.action('%s: Sign images' % sha_algo)
118 util.run_and_log(cons, [mkimage, '-F', '-k', tmpdir, '-K', dtb,
121 def replace_fit_totalsize(size):
122 """Replace FIT header's totalsize with something greater.
124 The totalsize must be less than or equal to FIT_SIGNATURE_MAX_SIZE.
125 If the size is greater, the signature verification should return false.
128 size: The new totalsize of the header
131 prev_size: The previous totalsize read from the header
134 with open(fit, 'r+b') as handle:
136 total_size = handle.read(4)
138 handle.write(struct.pack(">I", size))
139 return struct.unpack(">I", total_size)[0]
141 def create_rsa_pair(name):
142 """Generate a new RSA key paid and certificate
145 name: Name of of the key (e.g. 'dev')
147 public_exponent = 65537
148 util.run_and_log(cons, 'openssl genpkey -algorithm RSA -out %s%s.key '
149 '-pkeyopt rsa_keygen_bits:2048 '
150 '-pkeyopt rsa_keygen_pubexp:%d' %
151 (tmpdir, name, public_exponent))
153 # Create a certificate containing the public key
154 util.run_and_log(cons, 'openssl req -batch -new -x509 -key %s%s.key '
155 '-out %s%s.crt' % (tmpdir, name, tmpdir, name))
157 def test_with_algo(sha_algo, padding):
158 """Test verified boot with the given hash algorithm.
160 This is the main part of the test code. The same procedure is followed
161 for both hashing algorithms.
164 sha_algo: Either 'sha1' or 'sha256', to select the algorithm to
167 # Compile our device tree files for kernel and U-Boot. These are
168 # regenerated here since mkimage will modify them (by adding a
170 dtc('sandbox-kernel.dts')
171 dtc('sandbox-u-boot.dts')
173 # Build the FIT, but don't sign anything yet
174 cons.log.action('%s: Test FIT with signed images' % sha_algo)
175 make_fit('sign-images-%s%s.its' % (sha_algo, padding))
176 run_bootm(sha_algo, 'unsigned images', 'dev-', True)
178 # Sign images with our dev keys
180 run_bootm(sha_algo, 'signed images', 'dev+', True)
182 # Create a fresh .dtb without the public keys
183 dtc('sandbox-u-boot.dts')
185 cons.log.action('%s: Test FIT with signed configuration' % sha_algo)
186 make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
187 run_bootm(sha_algo, 'unsigned config', '%s+ OK' % sha_algo, True)
189 # Sign images with our dev keys
191 run_bootm(sha_algo, 'signed config', 'dev+', True)
193 cons.log.action('%s: Check signed config on the host' % sha_algo)
195 util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', dtb])
197 # Make sure that U-Boot checks that the config is in the list of hashed
198 # nodes. If it isn't, a security bypass is possible.
199 with open(fit, 'rb') as fd:
200 root, strblock = vboot_forge.read_fdt(fd)
201 root, strblock = vboot_forge.manipulate(root, strblock)
202 with open(fit, 'w+b') as fd:
203 vboot_forge.write_fdt(root, strblock, fd)
204 util.run_and_log_expect_exception(
205 cons, [fit_check_sign, '-f', fit, '-k', dtb],
206 1, 'Failed to verify required signature')
208 run_bootm(sha_algo, 'forged config', 'Bad Data Hash', False)
210 # Create a new properly signed fit and replace header bytes
211 make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
213 bcfg = u_boot_console.config.buildconfig
214 max_size = int(bcfg.get('config_fit_signature_max_size', 0x10000000), 0)
215 existing_size = replace_fit_totalsize(max_size + 1)
216 run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash',
218 cons.log.action('%s: Check overflowed FIT header totalsize' % sha_algo)
220 # Replace with existing header bytes
221 replace_fit_totalsize(existing_size)
222 run_bootm(sha_algo, 'signed config', 'dev+', True)
223 cons.log.action('%s: Check default FIT header totalsize' % sha_algo)
225 # Increment the first byte of the signature, which should cause failure
226 sig = util.run_and_log(cons, 'fdtget -t bx %s %s value' %
228 byte_list = sig.split()
229 byte = int(byte_list[0], 16)
230 byte_list[0] = '%x' % (byte + 1)
231 sig = ' '.join(byte_list)
232 util.run_and_log(cons, 'fdtput -t bx %s %s value %s' %
233 (fit, sig_node, sig))
235 run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash',
238 cons.log.action('%s: Check bad config on the host' % sha_algo)
239 util.run_and_log_expect_exception(
240 cons, [fit_check_sign, '-f', fit, '-k', dtb],
241 1, 'Failed to verify required signature')
243 def test_required_key(sha_algo, padding):
244 """Test verified boot with the given hash algorithm.
246 This function tests if U-Boot rejects an image when a required key isn't
250 sha_algo: Either 'sha1' or 'sha256', to select the algorithm to use
252 # Compile our device tree files for kernel and U-Boot. These are
253 # regenerated here since mkimage will modify them (by adding a
255 dtc('sandbox-kernel.dts')
256 dtc('sandbox-u-boot.dts')
258 cons.log.action('%s: Test FIT with configs images' % sha_algo)
260 # Build the FIT with prod key (keys required) and sign it. This puts the
261 # signature into sandbox-u-boot.dtb, marked 'required'
262 make_fit('sign-configs-%s%s-prod.its' % (sha_algo, padding))
265 # Build the FIT with dev key (keys NOT required). This adds the
266 # signature into sandbox-u-boot.dtb, NOT marked 'required'.
267 make_fit('sign-configs-%s%s.its' % (sha_algo, padding))
270 # So now sandbox-u-boot.dtb two signatures, for the prod and dev keys.
271 # Only the prod key is set as 'required'. But FIT we just built has
272 # a dev signature only (sign_fit() overwrites the FIT).
273 # Try to boot the FIT with dev key. This FIT should not be accepted by
274 # U-Boot because the prod key is required.
275 run_bootm(sha_algo, 'required key', '', False)
277 cons = u_boot_console
278 tmpdir = cons.config.result_dir + '/'
279 datadir = cons.config.source_dir + '/test/py/tests/vboot/'
280 fit = '%stest.fit' % tmpdir
281 mkimage = cons.config.build_dir + '/tools/mkimage'
282 fit_check_sign = cons.config.build_dir + '/tools/fit_check_sign'
283 dtc_args = '-I dts -O dtb -i %s' % tmpdir
284 dtb = '%ssandbox-u-boot.dtb' % tmpdir
285 sig_node = '/configurations/conf-1/signature'
287 create_rsa_pair('dev')
288 create_rsa_pair('prod')
290 # Create a number kernel image with zeroes
291 with open('%stest-kernel.bin' % tmpdir, 'w') as fd:
292 fd.write(500 * chr(0))
295 # We need to use our own device tree file. Remember to restore it
297 old_dtb = cons.config.dtb
298 cons.config.dtb = dtb
300 test_required_key(sha_algo, padding)
302 test_with_algo(sha_algo, padding)
304 # Go back to the original U-Boot with the correct dtb.
305 cons.config.dtb = old_dtb