# SPDX-License-Identifier: GPL-2.0+ # Copyright (c) 2016, Google Inc. # # U-Boot Verified Boot Test """ This tests verified boot in the following ways: For image verification: - Create FIT (unsigned) with mkimage - Check that verification shows that no keys are verified - Sign image - Check that verification shows that a key is now verified For configuration verification: - Corrupt signature and check for failure - Create FIT (with unsigned configuration) with mkimage - Check that image verification works - Sign the FIT and mark the key as 'required' for verification - Check that image verification works - Corrupt the signature - Check that image verification no-longer works Tests run with both SHA1 and SHA256 hashing. """ import pytest import sys import struct import u_boot_utils as util @pytest.mark.boardspec('sandbox') @pytest.mark.buildconfigspec('fit_signature') @pytest.mark.requiredtool('dtc') @pytest.mark.requiredtool('fdtget') @pytest.mark.requiredtool('fdtput') @pytest.mark.requiredtool('openssl') def test_vboot(u_boot_console): """Test verified boot signing with mkimage and verification with 'bootm'. This works using sandbox only as it needs to update the device tree used by U-Boot to hold public keys from the signing process. The SHA1 and SHA256 tests are combined into a single test since the key-generation process is quite slow and we want to avoid doing it twice. """ def dtc(dts): """Run the device tree compiler to compile a .dts file The output file will be the same as the input file but with a .dtb extension. Args: dts: Device tree file to compile. """ dtb = dts.replace('.dts', '.dtb') util.run_and_log(cons, 'dtc %s %s%s -O dtb ' '-o %s%s' % (dtc_args, datadir, dts, tmpdir, dtb)) def run_bootm(sha_algo, test_type, expect_string, boots): """Run a 'bootm' command U-Boot. This always starts a fresh U-Boot instance since the device tree may contain a new public key. Args: test_type: A string identifying the test type. expect_string: A string which is expected in the output. sha_algo: Either 'sha1' or 'sha256', to select the algorithm to use. boots: A boolean that is True if Linux should boot and False if we are expected to not boot """ cons.restart_uboot() with cons.log.section('Verified boot %s %s' % (sha_algo, test_type)): output = cons.run_command_list( ['sb load hostfs - 100 %stest.fit' % tmpdir, 'fdt addr 100', 'bootm 100']) assert(expect_string in ''.join(output)) if boots: assert('sandbox: continuing, as we cannot run' in ''.join(output)) def make_fit(its): """Make a new FIT from the .its source file. This runs 'mkimage -f' to create a new FIT. Args: its: Filename containing .its source. """ util.run_and_log(cons, [mkimage, '-D', dtc_args, '-f', '%s%s' % (datadir, its), fit]) def sign_fit(sha_algo): """Sign the FIT Signs the FIT and writes the signature into it. It also writes the public key into the dtb. Args: sha_algo: Either 'sha1' or 'sha256', to select the algorithm to use. """ cons.log.action('%s: Sign images' % sha_algo) util.run_and_log(cons, [mkimage, '-F', '-k', tmpdir, '-K', dtb, '-r', fit]) def replace_fit_totalsize(size): """Replace FIT header's totalsize with something greater. The totalsize must be less than or equal to FIT_SIGNATURE_MAX_SIZE. If the size is greater, the signature verification should return false. Args: size: The new totalsize of the header Returns: prev_size: The previous totalsize read from the header """ total_size = 0 with open(fit, 'r+b') as handle: handle.seek(4) total_size = handle.read(4) handle.seek(4) handle.write(struct.pack(">I", size)) return struct.unpack(">I", total_size)[0] def test_with_algo(sha_algo): """Test verified boot with the given hash algorithm. This is the main part of the test code. The same procedure is followed for both hashing algorithms. Args: sha_algo: Either 'sha1' or 'sha256', to select the algorithm to use. """ # Compile our device tree files for kernel and U-Boot. These are # regenerated here since mkimage will modify them (by adding a # public key) below. dtc('sandbox-kernel.dts') dtc('sandbox-u-boot.dts') # Build the FIT, but don't sign anything yet cons.log.action('%s: Test FIT with signed images' % sha_algo) make_fit('sign-images-%s.its' % sha_algo) run_bootm(sha_algo, 'unsigned images', 'dev-', True) # Sign images with our dev keys sign_fit(sha_algo) run_bootm(sha_algo, 'signed images', 'dev+', True) # Create a fresh .dtb without the public keys dtc('sandbox-u-boot.dts') cons.log.action('%s: Test FIT with signed configuration' % sha_algo) make_fit('sign-configs-%s.its' % sha_algo) run_bootm(sha_algo, 'unsigned config', '%s+ OK' % sha_algo, True) # Sign images with our dev keys sign_fit(sha_algo) run_bootm(sha_algo, 'signed config', 'dev+', True) cons.log.action('%s: Check signed config on the host' % sha_algo) util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', tmpdir, '-k', dtb]) # Replace header bytes bcfg = u_boot_console.config.buildconfig max_size = int(bcfg.get('config_fit_signature_max_size', 0x10000000), 0) existing_size = replace_fit_totalsize(max_size + 1) run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash', False) cons.log.action('%s: Check overflowed FIT header totalsize' % sha_algo) # Replace with existing header bytes replace_fit_totalsize(existing_size) run_bootm(sha_algo, 'signed config', 'dev+', True) cons.log.action('%s: Check default FIT header totalsize' % sha_algo) # Increment the first byte of the signature, which should cause failure sig = util.run_and_log(cons, 'fdtget -t bx %s %s value' % (fit, sig_node)) byte_list = sig.split() byte = int(byte_list[0], 16) byte_list[0] = '%x' % (byte + 1) sig = ' '.join(byte_list) util.run_and_log(cons, 'fdtput -t bx %s %s value %s' % (fit, sig_node, sig)) run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash', False) cons.log.action('%s: Check bad config on the host' % sha_algo) util.run_and_log_expect_exception(cons, [fit_check_sign, '-f', fit, '-k', dtb], 1, 'Failed to verify required signature') cons = u_boot_console tmpdir = cons.config.result_dir + '/' tmp = tmpdir + 'vboot.tmp' datadir = cons.config.source_dir + '/test/py/tests/vboot/' fit = '%stest.fit' % tmpdir mkimage = cons.config.build_dir + '/tools/mkimage' fit_check_sign = cons.config.build_dir + '/tools/fit_check_sign' dtc_args = '-I dts -O dtb -i %s' % tmpdir dtb = '%ssandbox-u-boot.dtb' % tmpdir sig_node = '/configurations/conf@1/signature@1' # Create an RSA key pair public_exponent = 65537 util.run_and_log(cons, 'openssl genpkey -algorithm RSA -out %sdev.key ' '-pkeyopt rsa_keygen_bits:2048 ' '-pkeyopt rsa_keygen_pubexp:%d ' '2>/dev/null' % (tmpdir, public_exponent)) # Create a certificate containing the public key util.run_and_log(cons, 'openssl req -batch -new -x509 -key %sdev.key -out ' '%sdev.crt' % (tmpdir, tmpdir)) # Create a number kernel image with zeroes with open('%stest-kernel.bin' % tmpdir, 'w') as fd: fd.write(5000 * chr(0)) try: # We need to use our own device tree file. Remember to restore it # afterwards. old_dtb = cons.config.dtb cons.config.dtb = dtb test_with_algo('sha1') test_with_algo('sha256') finally: # Go back to the original U-Boot with the correct dtb. cons.config.dtb = old_dtb cons.restart_uboot()