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python-tuf/tests/test_api.py
Jussi Kukkonen 13e20e9954 Metadata API: Make Metadata Generic 
When we use Metadata, it is helpful if the specific signed type (and all of
the signed types attribute types are correctly annotated. Currently this is
not possible.

Making Metadata Generic with constraint T, where

    T = TypeVar("T", "Root", "Timestamp", "Snapshot", "Targets")

allows these annotations. Using Generic annotations is completely
optional so all existing code still works -- the changes in test code
are done to make IDE annotations more useful in the test code, not
because they are required.

Examples:

    md = Metadata[Root].from_bytes(data)
    md:Metadata[Root] = Metadata.from_bytes(data)

In both examples md.signed is now statically typed as "Root" allowing IDE
annotations and static type checking by mypy.

Note that it's not possible to validate that "data" actually contains a
root metadata at runtime in these examples as the annotations are _not_
visible at runtime at all: new constructors would have to be added for that.

from_file() is now a class method like from_bytes() to make sure both
have the same definition of "T" when from_file() calls from_bytes():
This makes mypy happy.

Partially fixes #1433

Signed-off-by: Jussi Kukkonen <jkukkonen@vmware.com>
2021-08-16 16:38:21 +03:00

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#!/usr/bin/env python
# Copyright 2020, New York University and the TUF contributors
# SPDX-License-Identifier: MIT OR Apache-2.0
""" Unit tests for api/metadata.py
"""
import json
import sys
import logging
import os
import shutil
import tempfile
import unittest
import copy
from datetime import datetime, timedelta
from dateutil.relativedelta import relativedelta
from tests import utils
from tuf import exceptions
from tuf.api.metadata import (
Metadata,
Root,
Snapshot,
Timestamp,
Targets,
Key,
Role,
MetaFile,
TargetFile,
Delegations,
DelegatedRole,
)
from tuf.api.serialization import (
DeserializationError
)
from tuf.api.serialization.json import (
JSONSerializer,
JSONDeserializer,
CanonicalJSONSerializer
)
from securesystemslib.interface import (
import_ed25519_publickey_from_file,
import_ed25519_privatekey_from_file
)
from securesystemslib.signer import (
SSlibSigner,
Signature
)
logger = logging.getLogger(__name__)
class TestMetadata(unittest.TestCase):
@classmethod
def setUpClass(cls):
# Create a temporary directory to store the repository, metadata, and
# target files. 'temporary_directory' must be deleted in
# TearDownClass() so that temporary files are always removed, even when
# exceptions occur.
cls.temporary_directory = tempfile.mkdtemp(dir=os.getcwd())
test_repo_data = os.path.join(
os.path.dirname(os.path.realpath(__file__)), 'repository_data')
cls.repo_dir = os.path.join(cls.temporary_directory, 'repository')
shutil.copytree(
os.path.join(test_repo_data, 'repository'), cls.repo_dir)
cls.keystore_dir = os.path.join(cls.temporary_directory, 'keystore')
shutil.copytree(
os.path.join(test_repo_data, 'keystore'), cls.keystore_dir)
# Load keys into memory
cls.keystore = {}
for role in ['delegation', 'snapshot', 'targets', 'timestamp']:
cls.keystore[role] = import_ed25519_privatekey_from_file(
os.path.join(cls.keystore_dir, role + '_key'),
password="password"
)
@classmethod
def tearDownClass(cls):
# Remove the temporary repository directory, which should contain all
# the metadata, targets, and key files generated for the test cases.
shutil.rmtree(cls.temporary_directory)
def test_generic_read(self):
for metadata, inner_metadata_cls in [
('root', Root),
('snapshot', Snapshot),
('timestamp', Timestamp),
('targets', Targets)]:
# Load JSON-formatted metdata of each supported type from file
# and from out-of-band read JSON string
path = os.path.join(self.repo_dir, 'metadata', metadata + '.json')
metadata_obj = Metadata.from_file(path)
with open(path, 'rb') as f:
metadata_obj2 = Metadata.from_bytes(f.read())
# Assert that both methods instantiate the right inner class for
# each metadata type and ...
self.assertTrue(
isinstance(metadata_obj.signed, inner_metadata_cls))
self.assertTrue(
isinstance(metadata_obj2.signed, inner_metadata_cls))
# ... and return the same object (compared by dict representation)
self.assertDictEqual(
metadata_obj.to_dict(), metadata_obj2.to_dict())
# Assert that it chokes correctly on an unknown metadata type
bad_metadata_path = 'bad-metadata.json'
bad_metadata = {'signed': {'_type': 'bad-metadata'}}
bad_string = json.dumps(bad_metadata).encode('utf-8')
with open(bad_metadata_path, 'wb') as f:
f.write(bad_string)
with self.assertRaises(DeserializationError):
Metadata.from_file(bad_metadata_path)
with self.assertRaises(DeserializationError):
Metadata.from_bytes(bad_string)
os.remove(bad_metadata_path)
def test_compact_json(self):
path = os.path.join(self.repo_dir, 'metadata', 'targets.json')
metadata_obj = Metadata.from_file(path)
self.assertTrue(
len(JSONSerializer(compact=True).serialize(metadata_obj)) <
len(JSONSerializer().serialize(metadata_obj)))
def test_read_write_read_compare(self):
for metadata in ['root', 'snapshot', 'timestamp', 'targets']:
path = os.path.join(self.repo_dir, 'metadata', metadata + '.json')
metadata_obj = Metadata.from_file(path)
path_2 = path + '.tmp'
metadata_obj.to_file(path_2)
metadata_obj_2 = Metadata.from_file(path_2)
self.assertDictEqual(
metadata_obj.to_dict(),
metadata_obj_2.to_dict())
os.remove(path_2)
def test_to_from_bytes(self):
for metadata in ["root", "snapshot", "timestamp", "targets"]:
path = os.path.join(self.repo_dir, 'metadata', metadata + '.json')
with open(path, 'rb') as f:
metadata_bytes = f.read()
metadata_obj = Metadata.from_bytes(metadata_bytes)
# Comparate that from_bytes/to_bytes doesn't change the content
# for two cases for the serializer: noncompact and compact.
# Case 1: test noncompact by overriding the default serializer.
self.assertEqual(
metadata_obj.to_bytes(JSONSerializer()), metadata_bytes
)
# Case 2: test compact by using the default serializer.
obj_bytes = metadata_obj.to_bytes()
metadata_obj_2 = Metadata.from_bytes(obj_bytes)
self.assertEqual(
metadata_obj_2.to_bytes(), obj_bytes
)
def test_sign_verify(self):
root_path = os.path.join(self.repo_dir, 'metadata', 'root.json')
root = Metadata[Root].from_file(root_path).signed
# Locate the public keys we need from root
targets_keyid = next(iter(root.roles["targets"].keyids))
targets_key = root.keys[targets_keyid]
snapshot_keyid = next(iter(root.roles["snapshot"].keyids))
snapshot_key = root.keys[snapshot_keyid]
timestamp_keyid = next(iter(root.roles["timestamp"].keyids))
timestamp_key = root.keys[timestamp_keyid]
# Load sample metadata (targets) and assert ...
path = os.path.join(self.repo_dir, 'metadata', 'targets.json')
metadata_obj = Metadata.from_file(path)
# ... it has a single existing signature,
self.assertEqual(len(metadata_obj.signatures), 1)
# ... which is valid for the correct key.
targets_key.verify_signature(metadata_obj)
with self.assertRaises(exceptions.UnsignedMetadataError):
snapshot_key.verify_signature(metadata_obj)
# Test verifying with explicitly set serializer
targets_key.verify_signature(metadata_obj, CanonicalJSONSerializer())
with self.assertRaises(exceptions.UnsignedMetadataError):
targets_key.verify_signature(metadata_obj, JSONSerializer())
sslib_signer = SSlibSigner(self.keystore['snapshot'])
# Append a new signature with the unrelated key and assert that ...
sig = metadata_obj.sign(sslib_signer, append=True)
# ... there are now two signatures, and
self.assertEqual(len(metadata_obj.signatures), 2)
# ... both are valid for the corresponding keys.
targets_key.verify_signature(metadata_obj)
snapshot_key.verify_signature(metadata_obj)
# ... the returned (appended) signature is for snapshot key
self.assertEqual(sig.keyid, snapshot_keyid)
sslib_signer = SSlibSigner(self.keystore['timestamp'])
# Create and assign (don't append) a new signature and assert that ...
metadata_obj.sign(sslib_signer, append=False)
# ... there now is only one signature,
self.assertEqual(len(metadata_obj.signatures), 1)
# ... valid for that key.
timestamp_key.verify_signature(metadata_obj)
with self.assertRaises(exceptions.UnsignedMetadataError):
targets_key.verify_signature(metadata_obj)
# Test failure on unknown scheme (securesystemslib UnsupportedAlgorithmError)
scheme = timestamp_key.scheme
timestamp_key.scheme = "foo"
with self.assertRaises(exceptions.UnsignedMetadataError):
timestamp_key.verify_signature(metadata_obj)
timestamp_key.scheme = scheme
# Test failure on broken public key data (securesystemslib CryptoError)
public = timestamp_key.keyval["public"]
timestamp_key.keyval["public"] = "ffff"
with self.assertRaises(exceptions.UnsignedMetadataError):
timestamp_key.verify_signature(metadata_obj)
timestamp_key.keyval["public"] = public
# Test failure with invalid signature (securesystemslib FormatError)
sig = metadata_obj.signatures[timestamp_keyid]
correct_sig = sig.signature
sig.signature = "foo"
with self.assertRaises(exceptions.UnsignedMetadataError):
timestamp_key.verify_signature(metadata_obj)
# Test failure with valid but incorrect signature
sig.signature = "ff"*64
with self.assertRaises(exceptions.UnsignedMetadataError):
timestamp_key.verify_signature(metadata_obj)
sig.signature = correct_sig
def test_metadata_base(self):
# Use of Snapshot is arbitrary, we're just testing the base class features
# with real data
snapshot_path = os.path.join(
self.repo_dir, 'metadata', 'snapshot.json')
md = Metadata.from_file(snapshot_path)
self.assertEqual(md.signed.version, 1)
md.signed.bump_version()
self.assertEqual(md.signed.version, 2)
self.assertEqual(md.signed.expires, datetime(2030, 1, 1, 0, 0))
md.signed.bump_expiration()
self.assertEqual(md.signed.expires, datetime(2030, 1, 2, 0, 0))
md.signed.bump_expiration(timedelta(days=365))
self.assertEqual(md.signed.expires, datetime(2031, 1, 2, 0, 0))
# Test is_expired with reference_time provided
is_expired = md.signed.is_expired(md.signed.expires)
self.assertTrue(is_expired)
is_expired = md.signed.is_expired(md.signed.expires + timedelta(days=1))
self.assertTrue(is_expired)
is_expired = md.signed.is_expired(md.signed.expires - timedelta(days=1))
self.assertFalse(is_expired)
# Test is_expired without reference_time,
# manipulating md.signed.expires
expires = md.signed.expires
md.signed.expires = datetime.utcnow()
is_expired = md.signed.is_expired()
self.assertTrue(is_expired)
md.signed.expires = datetime.utcnow() + timedelta(days=1)
is_expired = md.signed.is_expired()
self.assertFalse(is_expired)
md.signed.expires = expires
# Test deserializing metadata with non-unique signatures:
data = md.to_dict()
data["signatures"].append({"keyid": data["signatures"][0]["keyid"], "sig": "foo"})
with self.assertRaises(ValueError):
Metadata.from_dict(data)
def test_metadata_snapshot(self):
snapshot_path = os.path.join(
self.repo_dir, 'metadata', 'snapshot.json')
snapshot = Metadata[Snapshot].from_file(snapshot_path)
# Create a MetaFile instance representing what we expect
# the updated data to be.
hashes = {'sha256': 'c2986576f5fdfd43944e2b19e775453b96748ec4fe2638a6d2f32f1310967095'}
fileinfo = MetaFile(2, 123, hashes)
self.assertNotEqual(
snapshot.signed.meta['role1.json'].to_dict(), fileinfo.to_dict()
)
snapshot.signed.update('role1', fileinfo)
self.assertEqual(
snapshot.signed.meta['role1.json'].to_dict(), fileinfo.to_dict()
)
def test_metadata_timestamp(self):
timestamp_path = os.path.join(
self.repo_dir, 'metadata', 'timestamp.json')
timestamp = Metadata[Timestamp].from_file(timestamp_path)
self.assertEqual(timestamp.signed.version, 1)
timestamp.signed.bump_version()
self.assertEqual(timestamp.signed.version, 2)
self.assertEqual(timestamp.signed.expires, datetime(2030, 1, 1, 0, 0))
timestamp.signed.bump_expiration()
self.assertEqual(timestamp.signed.expires, datetime(2030, 1, 2, 0, 0))
timestamp.signed.bump_expiration(timedelta(days=365))
self.assertEqual(timestamp.signed.expires, datetime(2031, 1, 2, 0, 0))
# Test whether dateutil.relativedelta works, this provides a much
# easier to use interface for callers
delta = relativedelta(days=1)
timestamp.signed.bump_expiration(delta)
self.assertEqual(timestamp.signed.expires, datetime(2031, 1, 3, 0, 0))
delta = relativedelta(years=5)
timestamp.signed.bump_expiration(delta)
self.assertEqual(timestamp.signed.expires, datetime(2036, 1, 3, 0, 0))
# Create a MetaFile instance representing what we expect
# the updated data to be.
hashes = {'sha256': '0ae9664468150a9aa1e7f11feecb32341658eb84292851367fea2da88e8a58dc'}
fileinfo = MetaFile(2, 520, hashes)
self.assertNotEqual(
timestamp.signed.meta['snapshot.json'].to_dict(), fileinfo.to_dict()
)
timestamp.signed.update(fileinfo)
self.assertEqual(
timestamp.signed.meta['snapshot.json'].to_dict(), fileinfo.to_dict()
)
def test_metadata_verify_delegate(self):
root_path = os.path.join(self.repo_dir, 'metadata', 'root.json')
root = Metadata[Root].from_file(root_path)
snapshot_path = os.path.join(
self.repo_dir, 'metadata', 'snapshot.json')
snapshot = Metadata[Snapshot].from_file(snapshot_path)
targets_path = os.path.join(
self.repo_dir, 'metadata', 'targets.json')
targets = Metadata[Targets].from_file(targets_path)
role1_path = os.path.join(
self.repo_dir, 'metadata', 'role1.json')
role1 = Metadata[Targets].from_file(role1_path)
role2_path = os.path.join(
self.repo_dir, 'metadata', 'role2.json')
role2 = Metadata[Targets].from_file(role2_path)
# test the expected delegation tree
root.verify_delegate('root', root)
root.verify_delegate('snapshot', snapshot)
root.verify_delegate('targets', targets)
targets.verify_delegate('role1', role1)
role1.verify_delegate('role2', role2)
# only root and targets can verify delegates
with self.assertRaises(TypeError):
snapshot.verify_delegate('snapshot', snapshot)
# verify fails for roles that are not delegated by delegator
with self.assertRaises(ValueError):
root.verify_delegate('role1', role1)
with self.assertRaises(ValueError):
targets.verify_delegate('targets', targets)
# verify fails when delegator has no delegations
with self.assertRaises(ValueError):
role2.verify_delegate('role1', role1)
# verify fails when delegate content is modified
expires = snapshot.signed.expires
snapshot.signed.bump_expiration()
with self.assertRaises(exceptions.UnsignedMetadataError):
root.verify_delegate('snapshot', snapshot)
snapshot.signed.expires = expires
# verify fails if roles keys do not sign the metadata
with self.assertRaises(exceptions.UnsignedMetadataError):
root.verify_delegate('timestamp', snapshot)
# Add a key to snapshot role, make sure the new sig fails to verify
ts_keyid = next(iter(root.signed.roles["timestamp"].keyids))
root.signed.add_key("snapshot", root.signed.keys[ts_keyid])
snapshot.signatures[ts_keyid] = Signature(ts_keyid, "ff"*64)
# verify succeeds if threshold is reached even if some signatures
# fail to verify
root.verify_delegate('snapshot', snapshot)
# verify fails if threshold of signatures is not reached
root.signed.roles['snapshot'].threshold = 2
with self.assertRaises(exceptions.UnsignedMetadataError):
root.verify_delegate('snapshot', snapshot)
# verify succeeds when we correct the new signature and reach the
# threshold of 2 keys
snapshot.sign(SSlibSigner(self.keystore['timestamp']), append=True)
root.verify_delegate('snapshot', snapshot)
def test_key_class(self):
keys = {
"59a4df8af818e9ed7abe0764c0b47b4240952aa0d179b5b78346c470ac30278d":{
"keytype": "ed25519",
"keyval": {
"public": "edcd0a32a07dce33f7c7873aaffbff36d20ea30787574ead335eefd337e4dacd"
},
"scheme": "ed25519"
},
}
for key_dict in keys.values():
# Test creating an instance without a required attribute.
for key in key_dict.keys():
test_key_dict = key_dict.copy()
del test_key_dict[key]
with self.assertRaises(KeyError):
Key.from_dict("id", test_key_dict)
def test_role_class(self):
roles = {
"root": {
"keyids": [
"4e777de0d275f9d28588dd9a1606cc748e548f9e22b6795b7cb3f63f98035fcb"
],
"threshold": 1
},
"snapshot": {
"keyids": [
"59a4df8af818e9ed7abe0764c0b47b4240952aa0d179b5b78346c470ac30278d"
],
"threshold": 1
},
}
for role_dict in roles.values():
# Test creating an instance without a required attribute.
for role_attr in role_dict.keys():
test_role_dict = role_dict.copy()
del test_role_dict[role_attr]
with self.assertRaises(KeyError):
Role.from_dict(test_role_dict)
def test_metadata_root(self):
root_path = os.path.join(
self.repo_dir, 'metadata', 'root.json')
root = Metadata[Root].from_file(root_path)
# Add a second key to root role
root_key2 = import_ed25519_publickey_from_file(
os.path.join(self.keystore_dir, 'root_key2.pub'))
keyid = root_key2['keyid']
key_metadata = Key(keyid, root_key2['keytype'], root_key2['scheme'],
root_key2['keyval'])
# Assert that root does not contain the new key
self.assertNotIn(keyid, root.signed.roles['root'].keyids)
self.assertNotIn(keyid, root.signed.keys)
# Add new root key
root.signed.add_key('root', key_metadata)
# Assert that key is added
self.assertIn(keyid, root.signed.roles['root'].keyids)
self.assertIn(keyid, root.signed.keys)
# Confirm that the newly added key does not break
# the object serialization
root.to_dict()
# Try adding the same key again and assert its ignored.
pre_add_keyid = root.signed.roles['root'].keyids.copy()
root.signed.add_key('root', key_metadata)
self.assertEqual(pre_add_keyid, root.signed.roles['root'].keyids)
# Remove the key
root.signed.remove_key('root', keyid)
# Assert that root does not contain the new key anymore
self.assertNotIn(keyid, root.signed.roles['root'].keyids)
self.assertNotIn(keyid, root.signed.keys)
with self.assertRaises(KeyError):
root.signed.remove_key('root', 'nosuchkey')
def test_delegation_class(self):
# empty keys and roles
delegations_dict = {"keys":{}, "roles":[]}
delegations = Delegations.from_dict(delegations_dict.copy())
self.assertEqual(delegations_dict, delegations.to_dict())
# Test some basic missing or broken input
invalid_delegations_dicts = [
{},
{"keys":None, "roles":None},
{"keys":{"foo":0}, "roles":[]},
{"keys":{}, "roles":["foo"]},
]
for d in invalid_delegations_dicts:
with self.assertRaises((KeyError, AttributeError)):
Delegations.from_dict(d)
def test_metadata_targets(self):
targets_path = os.path.join(
self.repo_dir, 'metadata', 'targets.json')
targets = Metadata[Targets].from_file(targets_path)
# Create a fileinfo dict representing what we expect the updated data to be
filename = 'file2.txt'
hashes = {
"sha256": "141f740f53781d1ca54b8a50af22cbf74e44c21a998fa2a8a05aaac2c002886b",
"sha512": "ef5beafa16041bcdd2937140afebd485296cd54f7348ecd5a4d035c09759608de467a7ac0eb58753d0242df873c305e8bffad2454aa48f44480f15efae1cacd0"
}
fileinfo = TargetFile(length=28, hashes=hashes)
# Assert that data is not aleady equal
self.assertNotEqual(
targets.signed.targets[filename].to_dict(), fileinfo.to_dict()
)
# Update an already existing fileinfo
targets.signed.update(filename, fileinfo)
# Verify that data is updated
self.assertEqual(
targets.signed.targets[filename].to_dict(), fileinfo.to_dict()
)
def test_length_and_hash_validation(self):
# Test metadata files' hash and length verification.
# Use timestamp to get a MetaFile object and snapshot
# for untrusted metadata file to verify.
timestamp_path = os.path.join(
self.repo_dir, 'metadata', 'timestamp.json')
timestamp = Metadata[Timestamp].from_file(timestamp_path)
snapshot_metafile = timestamp.signed.meta["snapshot.json"]
snapshot_path = os.path.join(
self.repo_dir, 'metadata', 'snapshot.json')
with open(snapshot_path, "rb") as file:
# test with data as a file object
snapshot_metafile.verify_length_and_hashes(file)
file.seek(0)
data = file.read()
# test with data as bytes
snapshot_metafile.verify_length_and_hashes(data)
# test exceptions
expected_length = snapshot_metafile.length
snapshot_metafile.length = 2345
self.assertRaises(exceptions.LengthOrHashMismatchError,
snapshot_metafile.verify_length_and_hashes, data)
snapshot_metafile.length = expected_length
snapshot_metafile.hashes = {'sha256': 'incorrecthash'}
self.assertRaises(exceptions.LengthOrHashMismatchError,
snapshot_metafile.verify_length_and_hashes, data)
snapshot_metafile.hashes = {'unsupported-alg': "8f88e2ba48b412c3843e9bb26e1b6f8fc9e98aceb0fbaa97ba37b4c98717d7ab"}
self.assertRaises(exceptions.LengthOrHashMismatchError,
snapshot_metafile.verify_length_and_hashes, data)
# Test wrong algorithm format (sslib.FormatError)
snapshot_metafile.hashes = { 256: "8f88e2ba48b412c3843e9bb26e1b6f8fc9e98aceb0fbaa97ba37b4c98717d7ab"}
self.assertRaises(exceptions.LengthOrHashMismatchError,
snapshot_metafile.verify_length_and_hashes, data)
# test optional length and hashes
snapshot_metafile.length = None
snapshot_metafile.hashes = None
snapshot_metafile.verify_length_and_hashes(data)
# Test target files' hash and length verification
targets_path = os.path.join(
self.repo_dir, 'metadata', 'targets.json')
targets = Metadata[Targets].from_file(targets_path)
file1_targetfile = targets.signed.targets['file1.txt']
filepath = os.path.join(
self.repo_dir, 'targets', 'file1.txt')
with open(filepath, "rb") as file1:
file1_targetfile.verify_length_and_hashes(file1)
# test exceptions
expected_length = file1_targetfile.length
file1_targetfile.length = 2345
self.assertRaises(exceptions.LengthOrHashMismatchError,
file1_targetfile.verify_length_and_hashes, file1)
file1_targetfile.length = expected_length
file1_targetfile.hashes = {'sha256': 'incorrecthash'}
self.assertRaises(exceptions.LengthOrHashMismatchError,
file1_targetfile.verify_length_and_hashes, file1)
# Run unit test.
if __name__ == '__main__':
utils.configure_test_logging(sys.argv)
unittest.main()
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