def test_with_tuf_mode_1(self):
# Simulate a slow retrieval attack.
# 'mode_1': When download begins,the server blocks the download for a long
# time by doing nothing before it sends the first byte of data.
server_process = self._start_slow_server('mode_1')
# Verify that the TUF client detects replayed metadata and refuses to
# continue the update process.
client_filepath = os.path.join(self.client_directory, 'file1.txt')
try:
file1_target = self.repository_updater.target('file1.txt')
self.repository_updater.download_target(file1_target,
self.client_directory)
# Verify that the specific 'tuf.SlowRetrievalError' exception is raised by
# each mirror.
except tuf.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, 'targets', 'file1.txt')
# Verify that 'file1.txt' is the culprit.
self.assertEqual(url_file, mirror_url)
self.assertTrue(
isinstance(mirror_error, tuf.DownloadLengthMismatchError))
else:
self.fail('TUF did not prevent a slow retrieval attack.')
finally:
self._stop_slow_server(server_process)
def check_match(self, object):
if not isinstance(object, dict):
raise tuf.FormatError('Expected a dict but got '+repr(object))
for key, value in six.iteritems(object):
self._key_schema.check_match(key)
self._value_schema.check_match(value)
def create_roledb_from_root_metadata(root_metadata):
"""
<Purpose>
Create a role database containing all of the unique roles found in
'root_metadata'.
<Arguments>
root_metadata:
A dictionary conformant to 'tuf.formats.ROOT_SCHEMA'. The roles found
in the 'roles' field of 'root_metadata' is needed by this function.
<Exceptions>
tuf.FormatError, if 'root_metadata' does not have the correct object format.
tuf.Error, if one of the roles found in 'root_metadata' contains an invalid
delegation (i.e., a nonexistent parent role).
<Side Effects>
Calls add_role().
The old role database is replaced.
<Returns>
None.
"""
# Does 'root_metadata' have the correct object format?
# This check will ensure 'root_metadata' has the appropriate number of objects
# and object types, and that all dict keys are properly named.
# Raises tuf.FormatError.
tuf.formats.ROOT_SCHEMA.check_match(root_metadata)
# Clear the role database.
_roledb_dict.clear()
# Do not modify the contents of the 'root_metadata' argument.
root_metadata = copy.deepcopy(root_metadata)
# Iterate through the roles found in 'root_metadata'
# and add them to '_roledb_dict'. Duplicates are avoided.
for rolename, roleinfo in six.iteritems(root_metadata['roles']):
if rolename == 'root':
roleinfo['version'] = root_metadata['version']
roleinfo['expires'] = root_metadata['expires']
roleinfo['signatures'] = []
roleinfo['signing_keyids'] = []
roleinfo['compressions'] = ['']
roleinfo['partial_loaded'] = False
if rolename.startswith('targets'):
roleinfo['paths'] = {}
roleinfo['delegations'] = {'keys': {}, 'roles': []}
try:
add_role(rolename, roleinfo)
# tuf.Error raised if the parent role of 'rolename' does not exist.
except tuf.Error as e:
logger.error(e)
raise
def test_get_target_hash(self):
# Test normal case.
expected_target_hashes = {
'/file1.txt': 'e3a3d89eb3b70ce3fbce6017d7b8c12d4abd5635427a0e8a238f53157df85b3d',
'/README.txt': '8faee106f1bb69f34aaf1df1e3c2e87d763c4d878cb96b91db13495e32ceb0b0',
'/packages/file2.txt': 'c9c4a5cdd84858dd6a23d98d7e6e6b2aec45034946c16b2200bc317c75415e92'
}
for filepath, target_hash in six.iteritems(expected_target_hashes):
self.assertTrue(tuf.formats.RELPATH_SCHEMA.matches(filepath))
self.assertTrue(tuf.formats.HASH_SCHEMA.matches(target_hash))
self.assertEqual(repo_lib.get_target_hash(filepath), target_hash)
# Test for improperly formatted argument.
self.assertRaises(tuf.FormatError, repo_lib.get_target_hash, 8)
def test_C1_get_target_hash(self):
# Test normal case.
expected_target_hashes = {
'/file1.txt': 'e3a3d89eb3b70ce3fbce6017d7b8c12d4abd5635427a0e8a238f53157df85b3d',
'/README.txt': '8faee106f1bb69f34aaf1df1e3c2e87d763c4d878cb96b91db13495e32ceb0b0',
'/warehouse/file2.txt': 'd543a573a2cec67026eff06e75702303559e64e705eba06f65799baaf0424417'
}
for filepath, target_hash in six.iteritems(expected_target_hashes):
self.assertTrue(tuf.formats.RELPATH_SCHEMA.matches(filepath))
self.assertTrue(tuf.formats.HASH_SCHEMA.matches(target_hash))
self.assertEqual(tuf.util.get_target_hash(filepath), target_hash)
# Test for improperly formatted argument.
self.assertRaises(tuf.FormatError, tuf.util.get_target_hash, 8)
def test_get_list_of_mirrors(self):
# Test: Normal case.
mirror_list = mirrors.get_list_of_mirrors('meta', 'release.txt',
self.mirrors)
self.assertEqual(len(mirror_list), 3)
for mirror, mirror_info in six.iteritems(self.mirrors):
url = mirror_info['url_prefix'] + '/metadata/release.txt'
self.assertTrue(url in mirror_list)
mirror_list = mirrors.get_list_of_mirrors('target', 'a.txt',
self.mirrors)
self.assertEqual(len(mirror_list), 1)
self.assertTrue(self.mirrors['mirror1']['url_prefix']+'/targets/a.txt' in \
mirror_list)
mirror_list = mirrors.get_list_of_mirrors('target', 'a/b',
self.mirrors)
self.assertEqual(len(mirror_list), 1)
self.assertTrue(self.mirrors['mirror1']['url_prefix']+'/targets/a/b' in \
mirror_list)
mirror1 = self.mirrors['mirror1']
del self.mirrors['mirror1']
mirror_list = mirrors.get_list_of_mirrors('target', 'a/b',
self.mirrors)
self.assertFalse(mirror_list)
self.mirrors['mirror1'] = mirror1
# Test: Invalid 'file_type'.
self.assertRaises(tuf.Error, mirrors.get_list_of_mirrors,
self.random_string(), 'a', self.mirrors)
self.assertRaises(tuf.Error, mirrors.get_list_of_mirrors, 12345, 'a',
self.mirrors)
# Test: Improperly formatted 'file_path'.
self.assertRaises(tuf.FormatError, mirrors.get_list_of_mirrors, 'meta',
12345, self.mirrors)
# Test: Improperly formatted 'mirrors_dict' object.
self.assertRaises(tuf.FormatError, mirrors.get_list_of_mirrors, 'meta',
'a', 12345)
self.assertRaises(tuf.FormatError, mirrors.get_list_of_mirrors, 'meta',
'a', ['a'])
self.assertRaises(tuf.FormatError, mirrors.get_list_of_mirrors, 'meta',
'a', {'a': 'b'})
def __init__(self, object_name='object', **required):
"""
<Purpose>
Create a new Object schema.
<Arguments>
object_name: A string identifier for the object argument.
A variable number of keyword arguments is accepted.
"""
# Ensure valid arguments.
for key, schema in six.iteritems(required):
if not isinstance(schema, Schema):
raise tuf.FormatError('Expected Schema but got '+repr(schema))
self._object_name = object_name
self._required = list(required.items())
def test_with_tuf(self):
# The same scenario outlined in test_without_tuf() is followed here, except
# with a TUF client. The TUF client performs a refresh of top-level
# metadata, which also includes 'timestamp.json'.
timestamp_path = os.path.join(self.repository_directory, 'metadata',
'timestamp.json')
# Modify the timestamp file on the remote repository. 'timestamp.json'
# must be properly updated and signed with 'repository_tool.py', otherwise
# the client will reject it as invalid metadata. The resulting
# 'timestamp.json' should be valid metadata, but expired (as intended).
repository = repo_tool.load_repository(self.repository_directory)
key_file = os.path.join(self.keystore_directory, 'timestamp_key')
timestamp_private = repo_tool.import_rsa_privatekey_from_file(key_file,
'password')
repository.timestamp.load_signing_key(timestamp_private)
# expire in 1 second.
datetime_object = tuf.formats.unix_timestamp_to_datetime(int(time.time() + 1))
repository.timestamp.expiration = datetime_object
repository.write()
# 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'))
# Verify that the TUF client detects outdated metadata and refuses to
# continue the update process. Sleep for at least 2 seconds to ensure
# 'repository.timestamp.expiration' is reached.
time.sleep(2)
try:
self.repository_updater.refresh()
except tuf.NoWorkingMirrorError as e:
for mirror_url, mirror_error in six.iteritems(e.mirror_errors):
self.assertTrue(isinstance(mirror_error, tuf.ExpiredMetadataError))
def _encode_canonical(object, output_function):
# Helper for encode_canonical. Older versions of json.encoder don't
# even let us replace the separators.
if isinstance(object, six.string_types):
output_function(_canonical_string_encoder(object))
elif object is True:
output_function("true")
elif object is False:
output_function("false")
elif object is None:
output_function("null")
elif isinstance(object, six.integer_types):
output_function(str(object))
elif isinstance(object, (tuple, list)):
output_function("[")
if len(object):
for item in object[:-1]:
_encode_canonical(item, output_function)
output_function(",")
_encode_canonical(object[-1], output_function)
output_function("]")
elif isinstance(object, dict):
output_function("{")
if len(object):
items = sorted(six.iteritems(object))
for key, value in items[:-1]:
output_function(_canonical_string_encoder(key))
output_function(":")
_encode_canonical(value, output_function)
output_function(",")
key, value = items[-1]
output_function(_canonical_string_encoder(key))
output_function(":")
_encode_canonical(value, output_function)
output_function("}")
else:
raise tuf.FormatError('I cannot encode ' + repr(object))
def test_with_tuf_mode_2(self):
# Simulate a slow retrieval attack.
# 'mode_2': During the download process, the server blocks the download
# by sending just several characters every few seconds.
server_process = self._start_slow_server('mode_2')
client_filepath = os.path.join(self.client_directory, 'file1.txt')
original_average_download_speed = tuf.conf.MIN_AVERAGE_DOWNLOAD_SPEED
tuf.conf.MIN_AVERAGE_DOWNLOAD_SPEED = 1
try:
file1_target = self.repository_updater.target('file1.txt')
self.repository_updater.download_target(file1_target,
self.client_directory)
# Verify that the specific 'tuf.SlowRetrievalError' exception is raised by
# each mirror. 'file1.txt' should be large enough to trigger a slow
# retrieval attack, otherwise the expected exception may not be
# consistently raised.
except tuf.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, 'targets', 'file1.txt')
# Verify that 'file1.txt' is the culprit.
self.assertEqual(url_file, mirror_url)
self.assertTrue(
isinstance(mirror_error, tuf.DownloadLengthMismatchError))
else:
# Another possibility is to check for a successfully downloaded
# 'file1.txt' at this point.
self.fail('TUF did not prevent a slow retrieval attack.')
finally:
self._stop_slow_server(server_process)
tuf.conf.MIN_AVERAGE_DOWNLOAD_SPEED = original_average_download_speed
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 = tuf.util.get_file_details(backup_timestamp)
previous_fileinfo = tuf.formats.make_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_rsa_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.write()
# 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 = tuf.util.get_file_details(timestamp_path)
new_fileinfo = tuf.formats.make_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, 'metadata',
'current', 'timestamp.json')
length, hashes = tuf.util.get_file_details(client_timestamp_path)
download_fileinfo = tuf.formats.make_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)
# 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.ReplayedMetadataError' is raised by each
# mirror.
except tuf.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, mirror_url)
self.assertTrue(
isinstance(mirror_error, tuf.ReplayedMetadataError))
else:
self.fail('TUF did not prevent a replay attack.')
def get_list_of_mirrors(file_type, file_path, mirrors_dict):
"""
<Purpose>
Get a list of mirror urls from a mirrors dictionary, provided the type
and the path of the file with respect to the base url.
<Arguments>
file_type:
Type of data needed for download, must correspond to one of the strings
in the list ['meta', 'target']. 'meta' for metadata file type or
'target' for target file type. It should correspond to
NAME_SCHEMA format.
file_path:
A relative path to the file that corresponds to RELPATH_SCHEMA format.
Ex: 'http://url_prefix/targets_path/file_path'
mirrors_dict:
A mirrors_dict object that corresponds to MIRRORDICT_SCHEMA, where
keys are strings and values are MIRROR_SCHEMA. An example format
of MIRROR_SCHEMA:
{'url_prefix': 'http://localhost:8001',
'metadata_path': 'metadata/',
'targets_path': 'targets/',
'confined_target_dirs': ['targets/snapshot1/', ...],
'custom': {...}}
The 'custom' field is optional.
<Exceptions>
tuf.Error, on unsupported 'file_type'.
tuf.FormatError, on bad argument.
<Return>
List of mirror urls corresponding to the file_type and file_path. If no
match is found, empty list is returned.
"""
# Checking if all the arguments have appropriate format.
tuf.formats.RELPATH_SCHEMA.check_match(file_path)
tuf.formats.MIRRORDICT_SCHEMA.check_match(mirrors_dict)
tuf.formats.NAME_SCHEMA.check_match(file_type)
# Verify 'file_type' is supported.
if file_type not in _SUPPORTED_FILE_TYPES:
message = 'Invalid file_type argument. '+ \
'Supported file types: '+repr(_SUPPORTED_FILE_TYPES)
raise tuf.Error(message)
# Reference to 'tuf.util.file_in_confined_directories()' (improve readability).
# This function checks whether a mirror should serve a file to the client.
# A client may be confined to certain paths on a repository mirror
# when fetching target files. This field may be set by the client when
# the repository mirror is added to the 'tuf.client.updater.Updater' object.
in_confined_directory = tuf.util.file_in_confined_directories
list_of_mirrors = []
for mirror_name, mirror_info in six.iteritems(mirrors_dict):
if file_type == 'meta':
base = mirror_info['url_prefix'] + '/' + mirror_info[
'metadata_path']
# 'file_type' == 'target'. 'file_type' should have been verified to contain
# a supported string value above (either 'meta' or 'target').
else:
targets_path = mirror_info['targets_path']
full_filepath = os.path.join(targets_path, file_path)
if not in_confined_directory(full_filepath,
mirror_info['confined_target_dirs']):
continue
base = mirror_info['url_prefix'] + '/' + mirror_info['targets_path']
# urllib.quote(string) replaces special characters in string using the %xx
# escape. This is done to avoid parsing issues of the URL on the server
# side. Do *NOT* pass URLs with Unicode characters without first encoding
# the URL as UTF-8. We need a long-term solution with #61.
# http://bugs.python.org/issue1712522
file_path = six.moves.urllib.parse.quote(file_path)
url = base + '/' + file_path.lstrip(os.sep)
list_of_mirrors.append(url)
return list_of_mirrors
def test_with_tuf(self):
# An attacker tries to trick a client into installing an extraneous target
# file (a valid file on the repository, in this case) by listing it in the
# project's metadata file. For the purposes of test_with_tuf(),
# 'targets/role1.json' is treated as the metadata file that indicates all
# the files needed to install/update the 'role1' project. The attacker
# simply adds the extraneous target file to 'role1.json', which the TUF
# client should reject as untrusted.
role1_filepath = os.path.join(self.repository_directory, 'metadata',
'targets', 'role1.json')
file1_filepath = os.path.join(self.repository_directory, 'targets',
'file1.txt')
length, hashes = tuf.util.get_file_details(file1_filepath)
role1_metadata = tuf.util.load_json_file(role1_filepath)
role1_metadata['signed']['targets']['/file2.txt'] = {}
role1_metadata['signed']['targets']['/file2.txt']['hashes'] = hashes
role1_metadata['signed']['targets']['/file2.txt']['length'] = length
tuf.formats.check_signable_object_format(role1_metadata)
with open(role1_filepath, 'wt') as file_object:
json.dump(role1_metadata, file_object, indent=1, sort_keys=True)
# Un-install the metadata of the top-level roles so that the client can
# download and detect the invalid 'role1.json'.
os.remove(
os.path.join(self.client_directory, 'metadata', 'current',
'snapshot.json'))
os.remove(
os.path.join(self.client_directory, 'metadata', 'current',
'targets.json'))
os.remove(
os.path.join(self.client_directory, 'metadata', 'current',
'timestamp.json'))
os.remove(
os.path.join(self.client_directory, 'metadata', 'current',
'targets', 'role1.json'))
# Verify that the TUF client rejects the invalid metadata and refuses to
# continue the update process.
self.repository_updater.refresh()
try:
self.repository_updater.targets_of_role('targets/role1')
# Verify that the specific 'tuf.BadHashError' exception is raised by each
# mirror.
except tuf.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', 'targets',
'role1.json')
# Verify that 'role1.json' is the culprit.
self.assertEqual(url_file, mirror_url)
self.assertTrue(isinstance(mirror_error, tuf.BadHashError))
else:
self.fail('TUF did not prevent an extraneous dependencies attack.')
def load_project(project_directory, prefix='', new_targets_location=None):
"""
<Purpose>
Return a Project object initialized with the contents of the metadata
files loaded from 'project_directory'.
<Arguments>
project_directory:
The path to the project's metadata and configuration file.
prefix:
The prefix for the metadata, if defined. It will replace the current
prefix, by first removing the existing one (saved).
new_targets_location:
For flat project configurations, project owner might want to reload the
project with a new location for the target files. This overwrites the
previous path to search for the target files.
<Exceptions>
tuf.FormatError, if 'project_directory' or any of the metadata files
are improperly formatted.
<Side Effects>
All the metadata files found in the project are loaded and their contents
stored in a libtuf.Repository object.
<Returns>
A tuf.developer_tool.Project object.
"""
# Does 'repository_directory' have the correct format?
# Raise 'tuf.FormatError' if there is a mismatch.
tuf.formats.PATH_SCHEMA.check_match(project_directory)
# Do the same for the prefix
tuf.formats.PATH_SCHEMA.check_match(prefix)
# Clear the role and key databases since we are loading in a new project.
tuf.roledb.clear_roledb()
tuf.keydb.clear_keydb()
# Locate metadata filepaths and targets filepath.
project_directory = os.path.abspath(project_directory)
# Load the cfg file and the project.
config_filename = os.path.join(project_directory, PROJECT_FILENAME)
try:
project_configuration = tuf.util.load_json_file(config_filename)
tuf.formats.PROJECT_CFG_SCHEMA.check_match(project_configuration)
except (OSError, IOError) as e:
raise
targets_directory = os.path.join(project_directory,
project_configuration['targets_location'])
if project_configuration['layout_type'] == 'flat':
project_directory, relative_junk = os.path.split(project_directory)
targets_directory = project_configuration['targets_location']
if new_targets_location is not None:
targets_directory = new_targets_location
metadata_directory = os.path.join(
project_directory, project_configuration['metadata_location'])
new_prefix = None
if prefix != '':
new_prefix = prefix
prefix = project_configuration['prefix']
# Load the project's filename.
project_name = project_configuration['project_name']
project_filename = project_name + METADATA_EXTENSION
# Create a blank project on the target directory.
project = Project(project_name, metadata_directory, targets_directory,
prefix)
project.threshold = project_configuration['threshold']
project._prefix = project_configuration['prefix']
project.layout_type = project_configuration['layout_type']
# Traverse the public keys and add them to the project.
keydict = project_configuration['public_keys']
for keyid in keydict:
key = format_metadata_to_key(keydict[keyid])
project.add_verification_key(key)
# Load the project's metadata.
targets_metadata_path = os.path.join(project_directory, metadata_directory,
project_filename)
signable = tuf.util.load_json_file(targets_metadata_path)
tuf.formats.check_signable_object_format(signable)
targets_metadata = signable['signed']
# Remove the prefix from the metadata.
targets_metadata = _strip_prefix_from_targets_metadata(
targets_metadata, prefix)
for signature in signable['signatures']:
project.add_signature(signature)
# Update roledb.py containing the loaded project attributes.
roleinfo = tuf.roledb.get_roleinfo(project_name)
roleinfo['signatures'].extend(signable['signatures'])
roleinfo['version'] = targets_metadata['version']
roleinfo['paths'] = targets_metadata['targets']
roleinfo['delegations'] = targets_metadata['delegations']
roleinfo['partial_loaded'] = False
# Check if the loaded metadata was partially written and update the
# flag in 'roledb.py'.
if _metadata_is_partially_loaded(project_name, signable, roleinfo):
roleinfo['partial_loaded'] = True
tuf.roledb.update_roleinfo(project_name, roleinfo)
for key_metadata in targets_metadata['delegations']['keys'].values():
key_object = tuf.keys.format_metadata_to_key(key_metadata)
tuf.keydb.add_key(key_object)
for role in targets_metadata['delegations']['roles']:
rolename = role['name']
roleinfo = {
'name': role['name'],
'keyids': role['keyids'],
'threshold': role['threshold'],
'compressions': [''],
'signing_keyids': [],
'signatures': [],
'partial_loaded': False,
'delegations': {
'keys': {},
'roles': []
}
}
tuf.roledb.add_role(rolename, roleinfo)
# Load delegated targets metadata.
# Walk the 'targets/' directory and generate the fileinfo of all the files
# listed. This information is stored in the 'meta' field of the release
# metadata object.
targets_objects = {}
loaded_metadata = []
targets_objects[project_name] = project
metadata_directory = os.path.join(project_directory, metadata_directory)
targets_metadata_directory = os.path.join(metadata_directory, project_name)
if os.path.exists(targets_metadata_directory) and \
os.path.isdir(targets_metadata_directory):
for root, directories, files in os.walk(targets_metadata_directory):
# 'files' here is a list of target file names.
for basename in files:
metadata_path = os.path.join(root, basename)
metadata_name = \
metadata_path[len(metadata_directory):].lstrip(os.path.sep)
# Strip the extension. The roledb does not include an appended '.json'
# extensions for each role.
if metadata_name.endswith(METADATA_EXTENSION):
extension_length = len(METADATA_EXTENSION)
metadata_name = metadata_name[:-extension_length]
else:
continue
signable = None
try:
signable = tuf.util.load_json_file(metadata_path)
except (ValueError, IOError, tuf.Error):
raise
# Strip the prefix from the local working copy, it will be added again
# when the targets metadata is written to disk.
metadata_object = signable['signed']
metadata_object = _strip_prefix_from_targets_metadata(
metadata_object, prefix)
roleinfo = tuf.roledb.get_roleinfo(metadata_name)
roleinfo['signatures'].extend(signable['signatures'])
roleinfo['version'] = metadata_object['version']
roleinfo['expires'] = metadata_object['expires']
roleinfo['paths'] = {}
for filepath, fileinfo in six.iteritems(
metadata_object['targets']):
roleinfo['paths'].update(
{filepath: fileinfo.get('custom', {})})
roleinfo['delegations'] = metadata_object['delegations']
roleinfo['partial_loaded'] = False
if os.path.exists(metadata_path + '.gz'):
roleinfo['compressions'].append('gz')
# If the metadata was partially loaded, update the roleinfo flag.
if _metadata_is_partially_loaded(metadata_name, signable,
roleinfo):
roleinfo['partial_loaded'] = True
tuf.roledb.update_roleinfo(metadata_name, roleinfo)
# Append to list of elements to avoid reloading repeated metadata.
loaded_metadata.append(metadata_name)
# Add the delegation.
new_targets_object = Targets(targets_directory, metadata_name,
roleinfo)
targets_object = \
targets_objects[tuf.roledb.get_parent_rolename(metadata_name)]
targets_objects[metadata_name] = new_targets_object
targets_object._delegated_roles[(os.path.basename(metadata_name))] = \
new_targets_object
# Add the keys specified in the delegations field of the Targets role.
for key_metadata in metadata_object['delegations'][
'keys'].values():
key_object = tuf.keys.format_metadata_to_key(key_metadata)
try:
tuf.keydb.add_key(key_object)
except tuf.KeyAlreadyExistsError:
pass
for role in metadata_object['delegations']['roles']:
rolename = role['name']
roleinfo = {
'name': role['name'],
'keyids': role['keyids'],
'threshold': role['threshold'],
'compressions': [''],
'signing_keyids': [],
'signatures': [],
'partial_loaded': False,
'delegations': {
'keys': {},
'roles': []
}
}
tuf.roledb.add_role(rolename, roleinfo)
if new_prefix:
project._prefix = new_prefix
return project
def test_with_tuf(self):
# Verify that a target file (on the remote repository) modified by an
# attacker, to contain a large amount of extra data, is not downloaded by
# the TUF client. First test that the valid target file is successfully
# downloaded.
file1_fileinfo = self.repository_updater.target('file1.txt')
destination = os.path.join(self.client_directory)
self.repository_updater.download_target(file1_fileinfo, destination)
client_target_path = os.path.join(destination, 'file1.txt')
self.assertTrue(os.path.exists(client_target_path))
# Verify the client's downloaded file matches the repository's.
target_path = os.path.join(self.repository_directory, 'targets',
'file1.txt')
length, hashes = tuf.util.get_file_details(client_target_path)
fileinfo = tuf.formats.make_fileinfo(length, hashes)
length, hashes = tuf.util.get_file_details(client_target_path)
download_fileinfo = tuf.formats.make_fileinfo(length, hashes)
self.assertEqual(fileinfo, download_fileinfo)
# Modify 'file1.txt' and confirm that the TUF client only downloads up to
# the expected file length.
with open(target_path, 'r+t') as file_object:
original_content = file_object.read()
file_object.write(original_content +
('append large amount of data' * 10000))
# Is the modified file actually larger?
large_length, hashes = tuf.util.get_file_details(target_path)
self.assertTrue(large_length > length)
os.remove(client_target_path)
self.repository_updater.download_target(file1_fileinfo, destination)
# A large amount of data has been appended to the original content. The
# extra data appended should be discarded by the client, so the downloaded
# file size and hash should not have changed.
length, hashes = tuf.util.get_file_details(client_target_path)
download_fileinfo = tuf.formats.make_fileinfo(length, hashes)
self.assertEqual(fileinfo, download_fileinfo)
# Test that the TUF client does not download large metadata files, as well.
timestamp_path = os.path.join(self.repository_directory, 'metadata',
'timestamp.json')
original_length, hashes = tuf.util.get_file_details(timestamp_path)
with open(timestamp_path, 'r+') as file_object:
timestamp_content = tuf.util.load_json_file(timestamp_path)
large_data = 'LargeTimestamp' * 10000
timestamp_content['signed']['_type'] = large_data
json.dump(timestamp_content, file_object, indent=1, sort_keys=True)
modified_length, hashes = tuf.util.get_file_details(timestamp_path)
self.assertTrue(modified_length > original_length)
# Does the TUF client download the upper limit of an unsafely fetched
# 'timestamp.json'? 'timestamp.json' must not be greater than
# 'tuf.conf.DEFAULT_TIMESTAMP_REQUIRED_LENGTH'.
try:
self.repository_updater.refresh()
except tuf.NoWorkingMirrorError as exception:
for mirror_url, mirror_error in six.iteritems(
exception.mirror_errors):
self.assertTrue(
isinstance(mirror_error, tuf.InvalidMetadataJSONError))
else:
self.fail('TUF did not prevent an endless data attack.')
def test_with_tuf(self):
# Scenario:
# An attacker tries to trick the client into installing files indicated by
# a previous release of its corresponding metatadata. The outdated metadata
# is properly named and was previously valid, but is no longer current
# according to the latest 'snapshot.json' role. Generate a new snapshot of
# the repository after modifying a target file of 'role1.json'.
# Backup 'role1.json' (the delegated role to be updated, and then inserted
# again for the mix-and-match attack.)
role1_path = os.path.join(self.repository_directory, 'metadata',
'targets', 'role1.json')
backup_role1 = os.path.join(self.repository_directory,
'role1.json.backup')
shutil.copy(role1_path, backup_role1)
# Backup 'file3.txt', specified by 'role1.json'.
file3_path = os.path.join(self.repository_directory, 'targets',
'file3.txt')
shutil.copy(file3_path, file3_path + '.backup')
# Re-generate the required metadata on the remote repository. The affected
# metadata must be properly updated and signed with 'repository_tool.py',
# otherwise the client will reject them as invalid metadata. The resulting
# metadata should be valid metadata.
repository = repo_tool.load_repository(self.repository_directory)
# Load the signing keys so that newly generated metadata is properly signed.
timestamp_keyfile = os.path.join(self.keystore_directory,
'timestamp_key')
role1_keyfile = os.path.join(self.keystore_directory, 'delegation_key')
snapshot_keyfile = os.path.join(self.keystore_directory,
'snapshot_key')
timestamp_private = \
repo_tool.import_rsa_privatekey_from_file(timestamp_keyfile, 'password')
role1_private = \
repo_tool.import_rsa_privatekey_from_file(role1_keyfile, 'password')
snapshot_private = \
repo_tool.import_rsa_privatekey_from_file(snapshot_keyfile, 'password')
repository.targets('role1').load_signing_key(role1_private)
repository.snapshot.load_signing_key(snapshot_private)
repository.timestamp.load_signing_key(timestamp_private)
# Modify a 'role1.json' target file, and add it to its metadata so that a
# new version is generated.
with open(file3_path, 'wt') as file_object:
file_object.write('This is role2\'s target file.')
repository.targets('role1').add_target(file3_path)
repository.write()
# 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'))
# Insert the previously valid 'role1.json'. The TUF client should reject it.
shutil.move(backup_role1, role1_path)
# Verify that the TUF client detects unexpected metadata (previously valid,
# but not up-to-date with the latest snapshot of the repository) and refuses
# to continue the update process.
# Refresh top-level metadata so that the client is aware of the latest
# snapshot of the repository.
self.repository_updater.refresh()
try:
self.repository_updater.targets_of_role('targets/role1')
# Verify that the specific 'tuf.BadHashError' exception is raised by each
# mirror.
except tuf.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', 'targets',
'role1.json')
# Verify that 'timestamp.json' is the culprit.
self.assertEqual(url_file, mirror_url)
self.assertTrue(isinstance(mirror_error, tuf.BadHashError))
else:
self.fail('TUF did not prevent a mix-and-match attack.')
def create_keydb_from_root_metadata(root_metadata):
"""
<Purpose>
Populate the key database with the unique keys found in 'root_metadata'.
The database dictionary will conform to 'tuf.formats.KEYDB_SCHEMA' and
have the form: {keyid: key, ...}.
The 'keyid' conforms to 'tuf.formats.KEYID_SCHEMA' and 'key' to its
respective type. In the case of RSA keys, this object would match
'RSAKEY_SCHEMA'.
<Arguments>
root_metadata:
A dictionary conformant to 'tuf.formats.ROOT_SCHEMA'. The keys found
in the 'keys' field of 'root_metadata' are needed by this function.
<Exceptions>
tuf.FormatError, if 'root_metadata' does not have the correct format.
<Side Effects>
A function to add the key to the database is called. In the case of RSA
keys, this function is add_key().
The old keydb key database is replaced.
<Returns>
None.
"""
# Does 'root_metadata' have the correct format?
# This check will ensure 'root_metadata' has the appropriate number of objects
# and object types, and that all dict keys are properly named.
# Raise 'tuf.FormatError' if the check fails.
tuf.formats.ROOT_SCHEMA.check_match(root_metadata)
# Clear the key database.
_keydb_dict.clear()
# Iterate the keys found in 'root_metadata' by converting them to
# 'RSAKEY_SCHEMA' if their type is 'rsa', and then adding them to the
# database.
for keyid, key_metadata in six.iteritems(root_metadata['keys']):
if key_metadata['keytype'] in _SUPPORTED_KEY_TYPES:
# 'key_metadata' is stored in 'KEY_SCHEMA' format. Call
# create_from_metadata_format() to get the key in 'RSAKEY_SCHEMA'
# format, which is the format expected by 'add_key()'.
key_dict = tuf.keys.format_metadata_to_key(key_metadata)
try:
add_key(key_dict, keyid)
# Although keyid duplicates should *not* occur (unique dict keys), log a
# warning and continue.
except tuf.KeyAlreadyExistsError as e: # pragma: no cover
logger.warning(e)
continue
# 'tuf.Error' raised if keyid does not match the keyid for 'rsakey_dict'.
except tuf.Error as e:
logger.error(e)
continue
else:
logger.warning(
'Root Metadata file contains a key with an invalid keytype.')
def __read_configuration(configuration_handler,
filename="tuf.interposition.json",
parent_repository_directory=None,
parent_ssl_certificates_directory=None):
"""
A generic function to read TUF interposition configurations off a file, and
then handle those configurations with a given function.
configuration_handler must be a function which accepts a
tuf.interposition.Configuration instance.
Returns the parsed configurations as a dictionary of configurations indexed
by hostnames.
"""
INVALID_TUF_CONFIGURATION = "Invalid configuration for {network_location}!"
INVALID_TUF_INTERPOSITION_JSON = "Invalid configuration in {filename}!"
NO_CONFIGURATIONS = "No configurations found in configuration in {filename}!"
# Configurations indexed by hostnames.
parsed_configurations = {}
try:
with open(filename) as tuf_interposition_json:
tuf_interpositions = json.load(tuf_interposition_json)
configurations = tuf_interpositions.get("configurations", {})
if len(configurations) == 0:
raise tuf.InvalidConfigurationError(
NO_CONFIGURATIONS.format(filename=filename))
else:
for network_location, configuration in six.iteritems(
configurations):
try:
configuration_parser = ConfigurationParser(
network_location,
configuration,
parent_repository_directory=
parent_repository_directory,
parent_ssl_certificates_directory=
parent_ssl_certificates_directory)
# configuration_parser.parse() returns a
# 'tuf.interposition.Configuration' object, which interposition
# uses to determine which URLs should be interposed.
configuration = configuration_parser.parse()
configuration_handler(configuration)
parsed_configurations[
configuration.hostname] = configuration
except:
logger.exception(
INVALID_TUF_CONFIGURATION.format(
network_location=network_location))
raise
except:
logger.exception(
INVALID_TUF_INTERPOSITION_JSON.format(filename=filename))
raise
else:
return parsed_configurations
