From d5f3aadacbc63df3b690d6fd9f0aa3f575b43356 Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Mon, 15 Feb 2021 17:08:08 -0700 Subject: [PATCH] test: Add tests for the 'evil' vboot attacks Add tests to check that these two attacks are mitigated by recent patches. Signed-off-by: Simon Glass Reported-by: Bruce Monroe Reported-by: Arie Haenel Reported-by: Julien Lenoir --- test/py/tests/test_vboot.py | 93 ++++++++++++++++++++++++++----------- 1 file changed, 65 insertions(+), 28 deletions(-) diff --git a/test/py/tests/test_vboot.py b/test/py/tests/test_vboot.py index e45800d94c..9cdc290b9f 100644 --- a/test/py/tests/test_vboot.py +++ b/test/py/tests/test_vboot.py @@ -24,22 +24,26 @@ For configuration verification: Tests run with both SHA1 and SHA256 hashing. """ +import shutil import struct import pytest import u_boot_utils as util import vboot_forge +import vboot_evil +# Only run the full suite on a few combinations, since it doesn't add any more +# test coverage. TESTDATA = [ - ['sha1', '', None, False], - ['sha1', '', '-E -p 0x10000', False], - ['sha1', '-pss', None, False], - ['sha1', '-pss', '-E -p 0x10000', False], - ['sha256', '', None, False], - ['sha256', '', '-E -p 0x10000', False], - ['sha256', '-pss', None, False], - ['sha256', '-pss', '-E -p 0x10000', False], - ['sha256', '-pss', None, True], - ['sha256', '-pss', '-E -p 0x10000', True], + ['sha1', '', None, False, True], + ['sha1', '', '-E -p 0x10000', False, False], + ['sha1', '-pss', None, False, False], + ['sha1', '-pss', '-E -p 0x10000', False, False], + ['sha256', '', None, False, False], + ['sha256', '', '-E -p 0x10000', False, False], + ['sha256', '-pss', None, False, False], + ['sha256', '-pss', '-E -p 0x10000', False, False], + ['sha256', '-pss', None, True, False], + ['sha256', '-pss', '-E -p 0x10000', True, True], ] @pytest.mark.boardspec('sandbox') @@ -48,8 +52,10 @@ TESTDATA = [ @pytest.mark.requiredtool('fdtget') @pytest.mark.requiredtool('fdtput') @pytest.mark.requiredtool('openssl') -@pytest.mark.parametrize("sha_algo,padding,sign_options,required", TESTDATA) -def test_vboot(u_boot_console, sha_algo, padding, sign_options, required): +@pytest.mark.parametrize("sha_algo,padding,sign_options,required,full_test", + TESTDATA) +def test_vboot(u_boot_console, sha_algo, padding, sign_options, required, + full_test): """Test verified boot signing with mkimage and verification with 'bootm'. This works using sandbox only as it needs to update the device tree used @@ -71,7 +77,7 @@ def test_vboot(u_boot_console, sha_algo, padding, sign_options, required): 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): + def run_bootm(sha_algo, test_type, expect_string, boots, fit=None): """Run a 'bootm' command U-Boot. This always starts a fresh U-Boot instance since the device tree may @@ -84,11 +90,14 @@ def test_vboot(u_boot_console, sha_algo, padding, sign_options, required): use. boots: A boolean that is True if Linux should boot and False if we are expected to not boot + fit: FIT filename to load and verify """ + if not fit: + fit = '%stest.fit' % tmpdir cons.restart_uboot() with cons.log.section('Verified boot %s %s' % (sha_algo, test_type)): output = cons.run_command_list( - ['host load hostfs - 100 %stest.fit' % tmpdir, + ['host load hostfs - 100 %s' % fit, 'fdt addr 100', 'bootm 100']) assert expect_string in ''.join(output) @@ -222,18 +231,41 @@ def test_vboot(u_boot_console, sha_algo, padding, sign_options, required): util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', dtb]) - # Make sure that U-Boot checks that the config is in the list of hashed - # nodes. If it isn't, a security bypass is possible. - with open(fit, 'rb') as fd: - root, strblock = vboot_forge.read_fdt(fd) - root, strblock = vboot_forge.manipulate(root, strblock) - with open(fit, 'w+b') as fd: - vboot_forge.write_fdt(root, strblock, fd) - util.run_and_log_expect_exception( - cons, [fit_check_sign, '-f', fit, '-k', dtb], - 1, 'Failed to verify required signature') - - run_bootm(sha_algo, 'forged config', 'Bad Data Hash', False) + if full_test: + # Make sure that U-Boot checks that the config is in the list of hashed + # nodes. If it isn't, a security bypass is possible. + ffit = '%stest.forged.fit' % tmpdir + shutil.copyfile(fit, ffit) + with open(ffit, 'rb') as fd: + root, strblock = vboot_forge.read_fdt(fd) + root, strblock = vboot_forge.manipulate(root, strblock) + with open(ffit, 'w+b') as fd: + vboot_forge.write_fdt(root, strblock, fd) + util.run_and_log_expect_exception( + cons, [fit_check_sign, '-f', ffit, '-k', dtb], + 1, 'Failed to verify required signature') + + run_bootm(sha_algo, 'forged config', 'Bad Data Hash', False, ffit) + + # Try adding an evil root node. This should be detected. + efit = '%stest.evilf.fit' % tmpdir + shutil.copyfile(fit, efit) + vboot_evil.add_evil_node(fit, efit, evil_kernel, 'fakeroot') + + util.run_and_log_expect_exception( + cons, [fit_check_sign, '-f', efit, '-k', dtb], + 1, 'Failed to verify required signature') + run_bootm(sha_algo, 'evil fakeroot', 'Bad Data Hash', False, efit) + + # Try adding an @ to the kernel node name. This should be detected. + efit = '%stest.evilk.fit' % tmpdir + shutil.copyfile(fit, efit) + vboot_evil.add_evil_node(fit, efit, evil_kernel, 'kernel@') + + util.run_and_log_expect_exception( + cons, [fit_check_sign, '-f', efit, '-k', dtb], + 1, 'Node name contains @') + run_bootm(sha_algo, 'evil kernel@', 'Bad Data Hash', False, efit) # Create a new properly signed fit and replace header bytes make_fit('sign-configs-%s%s.its' % (sha_algo, padding)) @@ -344,8 +376,13 @@ def test_vboot(u_boot_console, sha_algo, padding, sign_options, required): create_rsa_pair('prod') # Create a number kernel image with zeroes - with open('%stest-kernel.bin' % tmpdir, 'w') as fd: - fd.write(500 * chr(0)) + with open('%stest-kernel.bin' % tmpdir, 'wb') as fd: + fd.write(500 * b'\0') + + # Create a second kernel image with ones + evil_kernel = '%stest-kernel1.bin' % tmpdir + with open(evil_kernel, 'wb') as fd: + fd.write(500 * b'\x01') try: # We need to use our own device tree file. Remember to restore it -- 2.39.5