python-tuf/tests/test_replay_attack.py
Martin Vrachev 028d1bc9f7 Make "utils" import more definite
Currently, we are importing the "utils" module in tests/utils
with "import utils".
This could become a problem when there is another module with
the same general name "utils" and could lead to import mistakes.

Signed-off-by: Martin Vrachev <mvrachev@vmware.com>
2020-11-23 22:17:31 +02:00

329 lines
14 KiB
Python
Executable file

#!/usr/bin/env python
# Copyright 2012 - 2017, New York University and the TUF contributors
# SPDX-License-Identifier: MIT OR Apache-2.0
"""
<Program Name>
test_replay_attack.py
<Author>
Konstantin Andrianov.
<Started>
February 22, 2012.
April 5, 2014.
Refactored to use the 'unittest' module (test conditions in code, rather
than verifying text output), use pre-generated repository files, and
discontinue use of the old repository tools. Expanded comments.
-vladimir.v.diaz
<Copyright>
See LICENSE-MIT OR LICENSE for licensing information.
<Purpose>
Simulate a replay, or rollback, attack. In a replay attack, a client is
tricked into installing software that is older than that which the client
previously knew to be available.
Note: There is no difference between 'updates' and 'target' files.
"""
# Help with Python 3 compatibility, where the print statement is a function, an
# implicit relative import is invalid, and the '/' operator performs true
# division. Example: print 'hello world' raises a 'SyntaxError' exception.
from __future__ import print_function
from __future__ import absolute_import
from __future__ import division
from __future__ import unicode_literals
import os
import tempfile
import datetime
import shutil
import logging
import unittest
import sys
import tuf.formats
import tuf.log
import tuf.client.updater as updater
import tuf.repository_tool as repo_tool
import tuf.unittest_toolbox as unittest_toolbox
from tests import utils
import securesystemslib
import six
# The repository tool is imported and logs console messages by default.
# Disable console log messages generated by this unit test.
repo_tool.disable_console_log_messages()
logger = logging.getLogger(__name__)
class TestReplayAttack(unittest_toolbox.Modified_TestCase):
@classmethod
def setUpClass(cls):
# Create a temporary directory to store the repository, metadata, and target
# files. 'temporary_directory' must be deleted in TearDownModule() so that
# temporary files are always removed, even when exceptions occur.
cls.temporary_directory = tempfile.mkdtemp(dir=os.getcwd())
# Launch a SimpleHTTPServer (serves files in the current directory).
# Test cases will request metadata and target files that have been
# pre-generated in 'tuf/tests/repository_data', which will be served by the
# SimpleHTTPServer launched here. The test cases of this unit test assume
# the pre-generated metadata files have a specific structure, such
# as a delegated role 'targets/role1', three target files, five key files,
# etc.
cls.server_process_handler = utils.TestServerProcess(log=logger)
@classmethod
def tearDownClass(cls):
# Cleans the resources and flush the logged lines (if any).
cls.server_process_handler.clean()
# Remove the temporary repository directory, which should contain all the
# metadata, targets, and key files generated of all the test cases.
shutil.rmtree(cls.temporary_directory)
def setUp(self):
# We are inheriting from custom class.
unittest_toolbox.Modified_TestCase.setUp(self)
self.repository_name = 'test_repository1'
# Copy the original repository files provided in the test folder so that
# any modifications made to repository files are restricted to the copies.
# The 'repository_data' directory is expected to exist in 'tuf/tests/'.
original_repository_files = os.path.join(os.getcwd(), 'repository_data')
temporary_repository_root = \
self.make_temp_directory(directory=self.temporary_directory)
# The original repository, keystore, and client directories will be copied
# for each test case.
original_repository = os.path.join(original_repository_files, 'repository')
original_client = os.path.join(original_repository_files, 'client')
original_keystore = os.path.join(original_repository_files, 'keystore')
# Save references to the often-needed client repository directories.
# Test cases need these references to access metadata and target files.
self.repository_directory = \
os.path.join(temporary_repository_root, 'repository')
self.client_directory = os.path.join(temporary_repository_root, 'client')
self.keystore_directory = os.path.join(temporary_repository_root, 'keystore')
# Copy the original 'repository', 'client', and 'keystore' directories
# to the temporary repository the test cases can use.
shutil.copytree(original_repository, self.repository_directory)
shutil.copytree(original_client, self.client_directory)
shutil.copytree(original_keystore, self.keystore_directory)
# Set the url prefix required by the 'tuf/client/updater.py' updater.
# 'path/to/tmp/repository' -> 'localhost:8001/tmp/repository'.
repository_basepath = self.repository_directory[len(os.getcwd()):]
url_prefix = 'http://localhost:' \
+ str(self.server_process_handler.port) + repository_basepath
# Setting 'tuf.settings.repository_directory' with the temporary client
# directory copied from the original repository files.
tuf.settings.repositories_directory = self.client_directory
self.repository_mirrors = {'mirror1': {'url_prefix': url_prefix,
'metadata_path': 'metadata',
'targets_path': 'targets'}}
# Create the repository instance. The test cases will use this client
# updater to refresh metadata, fetch target files, etc.
self.repository_updater = updater.Updater(self.repository_name,
self.repository_mirrors)
def tearDown(self):
# Modified_TestCase.tearDown() automatically deletes temporary files and
# directories that may have been created during each test case.
unittest_toolbox.Modified_TestCase.tearDown(self)
tuf.roledb.clear_roledb(clear_all=True)
tuf.keydb.clear_keydb(clear_all=True)
# Logs stdout and stderr from the sever subprocess.
self.server_process_handler.flush_log()
def test_without_tuf(self):
# Scenario:
# 'timestamp.json' specifies the latest version of the repository files.
# A client should only accept the same version number (specified in the
# file) of the metadata, or greater. A version number less than the one
# currently trusted should be rejected. A non-TUF client may use a
# different mechanism for determining versions of metadata, but version
# numbers in this integrations because that is what TUF uses.
#
# Modify the repository's timestamp.json' so that a new version is generated
# and accepted by the client, and backup the previous version. The previous
# is then returned the next time the client requests an update. A non-TUF
# client (without a way to detect older versions of metadata, and thus
# updates) is expected to download older metadata and outdated files.
# Verify that the older version of timestamp.json' is downloaded by the
# non-TUF client.
# Backup the current version of 'timestamp'. It will be used as the
# outdated version returned to the client. The repository tool removes
# obsolete metadadata, so do *not* save the backup version in the
# repository's metadata directory.
timestamp_path = os.path.join(self.repository_directory, 'metadata',
'timestamp.json')
backup_timestamp = os.path.join(self.repository_directory,
'timestamp.json.backup')
shutil.copy(timestamp_path, backup_timestamp)
# The fileinfo of the previous version is saved to verify that it is indeed
# accepted by the non-TUF client.
length, hashes = securesystemslib.util.get_file_details(backup_timestamp)
previous_fileinfo = tuf.formats.make_targets_fileinfo(length, hashes)
# Modify the timestamp file on the remote repository.
repository = repo_tool.load_repository(self.repository_directory)
key_file = os.path.join(self.keystore_directory, 'timestamp_key')
timestamp_private = repo_tool.import_ed25519_privatekey_from_file(key_file,
'password')
repository.timestamp.load_signing_key(timestamp_private)
# Set an arbitrary expiration so that the repository tool generates a new
# version.
repository.timestamp.expiration = datetime.datetime(2030, 1, 1, 12, 12)
repository.writeall()
# Move the staged metadata to the "live" metadata.
shutil.rmtree(os.path.join(self.repository_directory, 'metadata'))
shutil.copytree(os.path.join(self.repository_directory, 'metadata.staged'),
os.path.join(self.repository_directory, 'metadata'))
# Save the fileinfo of the new version generated to verify that it is
# saved by the client.
length, hashes = securesystemslib.util.get_file_details(timestamp_path)
new_fileinfo = tuf.formats.make_targets_fileinfo(length, hashes)
url_prefix = self.repository_mirrors['mirror1']['url_prefix']
url_file = os.path.join(url_prefix, 'metadata', 'timestamp.json')
client_timestamp_path = os.path.join(self.client_directory,
self.repository_name, 'metadata', 'current', 'timestamp.json')
# On Windows, the URL portion should not contain back slashes.
six.moves.urllib.request.urlretrieve(url_file.replace('\\', '/'), client_timestamp_path)
length, hashes = securesystemslib.util.get_file_details(client_timestamp_path)
download_fileinfo = tuf.formats.make_targets_fileinfo(length, hashes)
# Verify 'download_fileinfo' is equal to the new version.
self.assertEqual(download_fileinfo, new_fileinfo)
# Restore the previous version of 'timestamp.json' on the remote repository
# and verify that the non-TUF client downloads it (expected, but not ideal).
shutil.move(backup_timestamp, timestamp_path)
# On Windows, the URL portion should not contain back slashes.
six.moves.urllib.request.urlretrieve(url_file.replace('\\', '/'), client_timestamp_path)
length, hashes = securesystemslib.util.get_file_details(client_timestamp_path)
download_fileinfo = tuf.formats.make_targets_fileinfo(length, hashes)
# Verify 'download_fileinfo' is equal to the previous version.
self.assertEqual(download_fileinfo, previous_fileinfo)
self.assertNotEqual(download_fileinfo, new_fileinfo)
def test_with_tuf(self):
# The same scenario outlined in test_without_tuf() is followed here, except
# with a TUF client (scenario description provided in the opening comment
# block of that test case.) The TUF client performs a refresh of top-level
# metadata, which also includes 'timestamp.json'.
# Backup the current version of 'timestamp'. It will be used as the
# outdated version returned to the client. The repository tool removes
# obsolete metadadata, so do *not* save the backup version in the
# repository's metadata directory.
timestamp_path = os.path.join(self.repository_directory, 'metadata',
'timestamp.json')
backup_timestamp = os.path.join(self.repository_directory,
'timestamp.json.backup')
shutil.copy(timestamp_path, backup_timestamp)
# The fileinfo of the previous version is saved to verify that it is indeed
# accepted by the non-TUF client.
length, hashes = securesystemslib.util.get_file_details(backup_timestamp)
previous_fileinfo = tuf.formats.make_targets_fileinfo(length, hashes)
# Modify the timestamp file on the remote repository.
repository = repo_tool.load_repository(self.repository_directory)
key_file = os.path.join(self.keystore_directory, 'timestamp_key')
timestamp_private = repo_tool.import_ed25519_privatekey_from_file(key_file,
'password')
repository.timestamp.load_signing_key(timestamp_private)
# Set an arbitrary expiration so that the repository tool generates a new
# version.
repository.timestamp.expiration = datetime.datetime(2030, 1, 1, 12, 12)
repository.writeall()
# Move the staged metadata to the "live" metadata.
shutil.rmtree(os.path.join(self.repository_directory, 'metadata'))
shutil.copytree(os.path.join(self.repository_directory, 'metadata.staged'),
os.path.join(self.repository_directory, 'metadata'))
# Save the fileinfo of the new version generated to verify that it is
# saved by the client.
length, hashes = securesystemslib.util.get_file_details(timestamp_path)
new_fileinfo = tuf.formats.make_targets_fileinfo(length, hashes)
# Refresh top-level metadata, including 'timestamp.json'. Installation of
# new version of 'timestamp.json' is expected.
self.repository_updater.refresh()
client_timestamp_path = os.path.join(self.client_directory,
self.repository_name, 'metadata', 'current', 'timestamp.json')
length, hashes = securesystemslib.util.get_file_details(client_timestamp_path)
download_fileinfo = tuf.formats.make_targets_fileinfo(length, hashes)
# Verify 'download_fileinfo' is equal to the new version.
self.assertEqual(download_fileinfo, new_fileinfo)
# Restore the previous version of 'timestamp.json' on the remote repository
# and verify that the non-TUF client downloads it (expected, but not ideal).
shutil.move(backup_timestamp, timestamp_path)
logger.info('Moving the timestamp.json backup to the current version.')
# Verify that the TUF client detects replayed metadata and refuses to
# continue the update process.
try:
self.repository_updater.refresh()
# Verify that the specific 'tuf.exceptions.ReplayedMetadataError' is raised by each
# mirror.
except tuf.exceptions.NoWorkingMirrorError as exception:
for mirror_url, mirror_error in six.iteritems(exception.mirror_errors):
url_prefix = self.repository_mirrors['mirror1']['url_prefix']
url_file = os.path.join(url_prefix, 'metadata', 'timestamp.json')
# Verify that 'timestamp.json' is the culprit.
self.assertEqual(url_file.replace('\\', '/'), mirror_url)
self.assertTrue(isinstance(mirror_error, tuf.exceptions.ReplayedMetadataError))
else:
self.fail('TUF did not prevent a replay attack.')
if __name__ == '__main__':
utils.configure_test_logging(sys.argv)
unittest.main()