mirror of
https://github.com/theupdateframework/python-tuf
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294 lines
12 KiB
Python
Executable file
294 lines
12 KiB
Python
Executable file
#!/usr/bin/env python
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# Copyright 2012 - 2017, New York University and the TUF contributors
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# SPDX-License-Identifier: MIT OR Apache-2.0
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"""
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<Program Name>
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test_endless_data_attack.py
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<Author>
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Konstantin Andrianov.
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<Started>
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March 13, 2012.
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April 3, 2014.
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Refactored to use the 'unittest' module (test conditions in code, rather
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than verifying text output), use pre-generated repository files, and
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discontinue use of the old repository tools. Minor edits to the test cases.
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-vladimir.v.diaz
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<Copyright>
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See LICENSE-MIT OR LICENSE for licensing information.
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<Purpose>
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Simulate an endless data attack, where an updater client tries to download a
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target file modified by an attacker to contain a large amount of data (a TUF
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client should only download up to the file's expected length). TUF and
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non-TUF client scenarios are tested.
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There is no difference between 'updates' and 'target' files.
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"""
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# Help with Python 3 compatibility, where the print statement is a function, an
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# implicit relative import is invalid, and the '/' operator performs true
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# division. Example: print 'hello world' raises a 'SyntaxError' exception.
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from __future__ import print_function
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import unicode_literals
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import os
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import tempfile
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import random
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import time
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import shutil
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import json
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import subprocess
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import logging
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import sys
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import unittest
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import tuf
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import tuf.formats
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import tuf.log
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import tuf.client.updater as updater
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import tuf.unittest_toolbox as unittest_toolbox
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import tuf.roledb
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import securesystemslib
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import six
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logger = logging.getLogger('tuf.test_endless_data_attack')
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class TestEndlessDataAttack(unittest_toolbox.Modified_TestCase):
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@classmethod
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def setUpClass(cls):
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# setUpClass() is called before any of the test cases are executed.
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# Create a temporary directory to store the repository, metadata, and target
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# files. 'temporary_directory' must be deleted in TearDownModule() so that
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# temporary files are always removed, even when exceptions occur.
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cls.temporary_directory = tempfile.mkdtemp(dir=os.getcwd())
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# Launch a SimpleHTTPServer (serves files in the current directory).
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# Test cases will request metadata and target files that have been
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# pre-generated in 'tuf/tests/repository_data', which will be served by the
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# SimpleHTTPServer launched here. The test cases of this unit test assume
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# the pre-generated metadata files have a specific structure, such
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# as a delegated role 'targets/role1', three target files, five key files,
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# etc.
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cls.SERVER_PORT = random.randint(30000, 45000)
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command = ['python', 'simple_server.py', str(cls.SERVER_PORT)]
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cls.server_process = subprocess.Popen(command, stderr=subprocess.PIPE)
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logger.info('Server process started.')
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logger.info('Server process id: '+str(cls.server_process.pid))
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logger.info('Serving on port: '+str(cls.SERVER_PORT))
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cls.url = 'http://localhost:'+str(cls.SERVER_PORT) + os.path.sep
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# NOTE: Following error is raised if a delay is not applied:
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# <urlopen error [Errno 111] Connection refused>
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time.sleep(.8)
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@classmethod
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def tearDownClass(cls):
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# tearDownModule() is called after all the test cases have run.
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# http://docs.python.org/2/library/unittest.html#class-and-module-fixtures
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# Remove the temporary repository directory, which should contain all the
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# metadata, targets, and key files generated of all the test cases.
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shutil.rmtree(cls.temporary_directory)
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# Kill the SimpleHTTPServer process.
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if cls.server_process.returncode is None:
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logger.info('Server process '+str(cls.server_process.pid)+' terminated.')
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cls.server_process.kill()
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def setUp(self):
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# We are inheriting from custom class.
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unittest_toolbox.Modified_TestCase.setUp(self)
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self.repository_name = 'test_repository1'
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# Copy the original repository files provided in the test folder so that
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# any modifications made to repository files are restricted to the copies.
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# The 'repository_data' directory is expected to exist in 'tuf/tests/'.
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original_repository_files = os.path.join(os.getcwd(), 'repository_data')
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temporary_repository_root = \
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self.make_temp_directory(directory=self.temporary_directory)
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# The original repository, keystore, and client directories will be copied
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# for each test case.
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original_repository = os.path.join(original_repository_files, 'repository')
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original_client = os.path.join(original_repository_files, 'client')
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# Save references to the often-needed client repository directories.
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# Test cases need these references to access metadata and target files.
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self.repository_directory = \
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os.path.join(temporary_repository_root, 'repository')
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self.client_directory = os.path.join(temporary_repository_root, 'client')
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# Copy the original 'repository', 'client', and 'keystore' directories
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# to the temporary repository the test cases can use.
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shutil.copytree(original_repository, self.repository_directory)
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shutil.copytree(original_client, self.client_directory)
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# Set the url prefix required by the 'tuf/client/updater.py' updater.
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# 'path/to/tmp/repository' -> 'localhost:8001/tmp/repository'.
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repository_basepath = self.repository_directory[len(os.getcwd()):]
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url_prefix = \
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'http://localhost:' + str(self.SERVER_PORT) + repository_basepath
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# Setting 'tuf.settings.repository_directory' with the temporary client
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# directory copied from the original repository files.
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tuf.settings.repositories_directory = self.client_directory
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self.repository_mirrors = {'mirror1': {'url_prefix': url_prefix,
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'metadata_path': 'metadata',
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'targets_path': 'targets',
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'confined_target_dirs': ['']}}
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# Create the repository instance. The test cases will use this client
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# updater to refresh metadata, fetch target files, etc.
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self.repository_updater = updater.Updater(self.repository_name,
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self.repository_mirrors)
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def tearDown(self):
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# Modified_TestCase.tearDown() automatically deletes temporary files and
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# directories that may have been created during each test case.
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unittest_toolbox.Modified_TestCase.tearDown(self)
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tuf.roledb.clear_roledb(clear_all=True)
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tuf.keydb.clear_keydb(clear_all=True)
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def test_without_tuf(self):
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# Verify that a target file replaced with a larger malicious version (to
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# simulate an endless data attack) is downloaded by a non-TUF client (i.e.,
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# a non-TUF client that does not verify hashes, detect mix-and-mix attacks,
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# etc.) A tuf client, on the other hand, should only download target files
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# up to their expected lengths, as explicitly specified in metadata, or
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# 'tuf.settings.py' (when retrieving 'timestamp.json' and 'root.json unsafely'.)
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# Test: Download a valid target file from the repository.
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# Ensure the target file to be downloaded has not already been downloaded,
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# and generate its file size and digest. The file size and digest is needed
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# to verify that the malicious file was indeed downloaded.
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target_path = os.path.join(self.repository_directory, 'targets', 'file1.txt')
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client_target_path = os.path.join(self.client_directory, 'file1.txt')
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self.assertFalse(os.path.exists(client_target_path))
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length, hashes = securesystemslib.util.get_file_details(target_path)
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fileinfo = tuf.formats.make_fileinfo(length, hashes)
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url_prefix = self.repository_mirrors['mirror1']['url_prefix']
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url_file = os.path.join(url_prefix, 'targets', 'file1.txt')
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# On Windows, the URL portion should not contain backslashes.
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six.moves.urllib.request.urlretrieve(url_file.replace('\\', '/'), client_target_path)
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self.assertTrue(os.path.exists(client_target_path))
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length, hashes = securesystemslib.util.get_file_details(client_target_path)
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download_fileinfo = tuf.formats.make_fileinfo(length, hashes)
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self.assertEqual(fileinfo, download_fileinfo)
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# Test: Download a target file that has been modified by an attacker with
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# extra data.
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with open(target_path, 'a') as file_object:
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file_object.write('append large amount of data' * 100000)
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large_length, hashes = securesystemslib.util.get_file_details(target_path)
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malicious_fileinfo = tuf.formats.make_fileinfo(large_length, hashes)
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# Is the modified file actually larger?
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self.assertTrue(large_length > length)
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# On Windows, the URL portion should not contain backslashes.
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six.moves.urllib.request.urlretrieve(url_file.replace('\\', '/'), client_target_path)
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length, hashes = securesystemslib.util.get_file_details(client_target_path)
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download_fileinfo = tuf.formats.make_fileinfo(length, hashes)
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# Verify 'download_fileinfo' is unequal to the original trusted version.
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self.assertNotEqual(download_fileinfo, fileinfo)
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# Verify 'download_fileinfo' is equal to the malicious version.
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self.assertEqual(download_fileinfo, malicious_fileinfo)
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def test_with_tuf(self):
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# Verify that a target file (on the remote repository) modified by an
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# attacker, to contain a large amount of extra data, is not downloaded by
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# the TUF client. First test that the valid target file is successfully
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# downloaded.
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file1_fileinfo = self.repository_updater.get_one_valid_targetinfo('file1.txt')
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destination = os.path.join(self.client_directory)
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self.repository_updater.download_target(file1_fileinfo, destination)
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client_target_path = os.path.join(destination, 'file1.txt')
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self.assertTrue(os.path.exists(client_target_path))
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# Verify the client's downloaded file matches the repository's.
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target_path = os.path.join(self.repository_directory, 'targets', 'file1.txt')
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length, hashes = securesystemslib.util.get_file_details(client_target_path)
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fileinfo = tuf.formats.make_fileinfo(length, hashes)
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length, hashes = securesystemslib.util.get_file_details(client_target_path)
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download_fileinfo = tuf.formats.make_fileinfo(length, hashes)
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self.assertEqual(fileinfo, download_fileinfo)
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# Modify 'file1.txt' and confirm that the TUF client only downloads up to
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# the expected file length.
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with open(target_path, 'a') as file_object:
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file_object.write('append large amount of data' * 10000)
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# Is the modified file actually larger?
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large_length, hashes = securesystemslib.util.get_file_details(target_path)
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self.assertTrue(large_length > length)
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os.remove(client_target_path)
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self.repository_updater.download_target(file1_fileinfo, destination)
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# A large amount of data has been appended to the original content. The
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# extra data appended should be discarded by the client, so the downloaded
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# file size and hash should not have changed.
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length, hashes = securesystemslib.util.get_file_details(client_target_path)
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download_fileinfo = tuf.formats.make_fileinfo(length, hashes)
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self.assertEqual(fileinfo, download_fileinfo)
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# Test that the TUF client does not download large metadata files, as well.
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timestamp_path = os.path.join(self.repository_directory, 'metadata',
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'timestamp.json')
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original_length, hashes = securesystemslib.util.get_file_details(timestamp_path)
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with open(timestamp_path, 'r+') as file_object:
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timestamp_content = securesystemslib.util.load_json_file(timestamp_path)
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large_data = 'LargeTimestamp' * 10000
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timestamp_content['signed']['_type'] = large_data
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json.dump(timestamp_content, file_object, indent=1, sort_keys=True)
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modified_length, hashes = securesystemslib.util.get_file_details(timestamp_path)
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self.assertTrue(modified_length > original_length)
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# Does the TUF client download the upper limit of an unsafely fetched
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# 'timestamp.json'? 'timestamp.json' must not be greater than
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# 'tuf.settings.DEFAULT_TIMESTAMP_REQUIRED_LENGTH'.
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try:
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self.repository_updater.refresh()
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except tuf.exceptions.NoWorkingMirrorError as exception:
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for mirror_url, mirror_error in six.iteritems(exception.mirror_errors):
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self.assertTrue(isinstance(mirror_error, securesystemslib.exceptions.Error))
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else:
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self.fail('TUF did not prevent an endless data attack.')
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if __name__ == '__main__':
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unittest.main()
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