def unlock_manifest(
manifest_filename: str,
private_key_filename: str,
load: Callable[[str, IOIter], IOIter],
options: OptionsDict,
) -> Manifest:
""" Load a manifest into local storage and unencrypt it
:param manifest_filename: the name of the manifest to unlock
:param private_key_filename: the private key file in PEM format used to encrypt the
manifest's keypair
:param load: the _load function from the backup store
:param options: backup store options
:returns: the requested Manifest
"""
local_manifest_filename = path_join(get_scratch_dir(), manifest_filename)
logger.debug(f'Unlocking manifest at {local_manifest_filename}')
# First use the private key to read the AES key and nonce used to encrypt the manifest
key_pair = b''
if options['use_encryption']:
key_pair = get_manifest_keypair(manifest_filename,
private_key_filename, load)
# Now use the key and nonce to decrypt the manifest
with IOIter() as encrypted_local_manifest, \
IOIter(local_manifest_filename, check_mtime=False) as local_manifest:
load(manifest_filename, encrypted_local_manifest)
decrypt_and_unpack(encrypted_local_manifest, local_manifest, key_pair,
options)
return Manifest(local_manifest_filename)
def compute_diff(
orig_file: IOIter,
new_file: IOIter,
diff_file: IOIter,
discard_diff_percentage: Optional[float] = None,
) -> IOIter:
""" Given an open original file and a new file, compute the diff between the two
:param orig_file: an IOIter object whose contents are the "original" data
:param new_file: an IOIter object whose contents are the "new" data
:param diff_file: an IOIter object where the diff data will be written
"""
total_written = 0
writer = diff_file.writer()
next(writer)
logger.debug2('beginning diff computation')
for orig_bytes, new_bytes in zip_longest(orig_file.reader(),
new_file.reader(),
fillvalue=b''):
diff = bsdiff4.diff(orig_bytes, new_bytes)
diff_str = str(len(diff)).encode() + SEPARATOR + diff
total_written += len(diff_str)
if discard_diff_percentage and total_written > orig_file.size * discard_diff_percentage:
raise DiffTooLargeException
writer.send(diff_str)
return diff_file
def _check_entry(entry: ManifestEntry, backup_store: BackupStore):
with IOIter() as orig_file, \
IOIter() as diff_file, \
IOIter() as restore_file:
backup_store.restore_entry(entry, orig_file, diff_file, restore_file)
sha = compute_sha(restore_file)
if sha != entry.sha:
raise MismatchedSHAError(
f'SHAs for {entry.abs_file_name} do not match')
def test_save(caplog, mock_backup_store):
with IOIter('/scratch/foo') as input1, IOIter(
'/scratch/asdf/bar') as input2:
mock_backup_store._save(input1, '/foo')
mock_backup_store._save(input2, '/asdf/bar')
assert os.path.exists('/fake/path/fake_backup/foo')
with open('/fake/path/fake_backup/foo', 'r') as f:
assert f.read() == "i'm a copy of foo"
assert os.path.exists('/fake/path/fake_backup/asdf/bar')
with open('/fake/path/fake_backup/asdf/bar', 'r') as f:
assert f.read() == "i'm a copy of bar"
def test_save(s3_client, mock_backup_store):
with IOIter('/scratch/foo') as input1, IOIter('/scratch/asdf/bar') as input2:
mock_backup_store._save(input1, '/foo')
mock_backup_store._save(input2, '/asdf/bar')
assert s3_client.get_object(
Bucket='test_bucket',
Key='/foo'
)['Body'].read() == b"i'm a copy of foo"
assert s3_client.get_object(
Bucket='test_bucket',
Key='/asdf/bar'
)['Body'].read() == b"i'm a copy of bar"
def decrypt_and_unpack(
input_file: IOIter,
output_file: IOIter,
key_pair: Optional[bytes],
options: OptionsDict,
) -> None:
""" Read encrypted, GZIPed data from an open file descriptor, and write the decoded data to
another file descriptor; verify the HMAC of the encrypted data to ensure integrity
:param input_file: an IOIter object to read compressed ciphertext from
:param output_file: an IOIter object to write plaintext data to
"""
key, nonce, signature = (
key_pair[:AES_KEY_SIZE],
key_pair[AES_KEY_SIZE:AES_KEY_SIZE + AES_BLOCK_SIZE],
key_pair[AES_KEY_SIZE + AES_BLOCK_SIZE:]
) if key_pair else (b'', b'', b'')
decrypted_data = b''
decrypt_fn: Callable[[bytes], bytes] = (
Cipher(AES(key), CTR(nonce), backend=default_backend()).decryptor().update
if options['use_encryption'] else identity
)
decompress_obj = zlib.decompressobj()
unzip_fn: Callable[[bytes], bytes] = (
decompress_obj.decompress # type: ignore
if options['use_compression'] else identity
)
hmac = HMAC(key, SHA256(), default_backend())
writer = output_file.writer(); next(writer)
for encrypted_data in input_file.reader():
if options['use_encryption']:
hmac.update(encrypted_data)
decrypted_data += decrypt_fn(encrypted_data)
logger.debug2(f'decrypt_fn returned {len(decrypted_data)} bytes')
block = unzip_fn(decrypted_data)
logger.debug2(f'unzip_fn returned {len(block)} bytes')
writer.send(block)
decrypted_data = decompress_obj.unused_data
# Decompress and write out the last block
if decrypted_data:
block = unzip_fn(decrypted_data)
logger.debug2(f'unzip_fn returned {len(block)} bytes')
writer.send(block)
try:
if options['use_encryption']:
hmac.verify(signature)
except InvalidSignature as e:
raise BackupCorruptedError("The file's signature did not match the data") from e
def lock_manifest(
manifest: Manifest,
private_key_filename: str,
save: Callable[[IOIter, str], None],
load: Callable[[str, IOIter], IOIter],
options: OptionsDict,
) -> None:
""" Save a manifest from local storage to the backup store
:param manifest: the manifest object to save
:param private_key_filename: the private key file in PEM format used to encrypt the
manifest's keypair
:param load: the _save function from the backup store
:param options: backup store options
:returns: the requested Manifest
"""
timestamp = time.time()
local_manifest_filename = manifest.filename
logger.debug(f'Locking manifest at {local_manifest_filename}')
# First generate a new key and nonce to encrypt the manifest
key_pair = generate_key_pair(options)
# Next, use that key and nonce to encrypt and save the manifest
new_manifest_filename = MANIFEST_FILE.format(ts=timestamp)
with IOIter(local_manifest_filename) as local_manifest, \
IOIter(local_manifest_filename + '.enc') as encrypted_manifest:
signature = compress_and_encrypt(local_manifest, encrypted_manifest,
key_pair, options)
save(encrypted_manifest, new_manifest_filename)
# Finally, save the manifest key/nonce along with its HMAC using the user's private key
if options['use_encryption']:
with IOIter(local_manifest_filename + '.key') as new_manifest_key:
new_manifest_key.fd.write(
encrypt_and_sign(key_pair + signature, private_key_filename))
new_manifest_key.fd.seek(0)
save(new_manifest_key, MANIFEST_KEY_FILE.format(ts=timestamp))
try:
unlock_manifest(new_manifest_filename, private_key_filename, load,
options)
except Exception:
logger.critical(
'The saved manifest could not be decrypted! '
'The contents of the most recent backup is inaccessible!')
raise
def _restore(
files_to_restore: List[ManifestEntry],
destination: str,
backup_store: BackupStore,
) -> None:
print('Beginning restore...')
os.makedirs(destination, exist_ok=True)
for f in files_to_restore:
stripped_abs_file_name = f.abs_file_name.removeprefix('/').replace(
':', '')
restore_file_name = path_join(destination, stripped_abs_file_name)
with IOIter() as orig_file, \
IOIter() as diff_file, \
IOIter(restore_file_name) as restore_file:
backup_store.restore_entry(f, orig_file, diff_file, restore_file)
print('Restore complete!\n')
def test_writer_tmp_file(block_size):
contents = b'asdfhjlkqwerty'
with IOIter(None, block_size=block_size) as tmp, \
mock.patch('backuppy.io.TemporaryFile', wraps=TemporaryFile) as mock_tmp_file:
writer = tmp.writer()
next(writer)
writer.send(contents)
tmp.fd.seek(0)
assert tmp.fd.read() == contents
assert mock_tmp_file.call_count == (len(contents) > block_size)
def _load(self, path: str, output_file: IOIter) -> IOIter:
path = path.replace('\\', '/')
logger.info(
f'Reading s3://{self._bucket}/{path} into {output_file.filename}')
response = self._client.get_object(Bucket=self._bucket, Key=path)
writer = output_file.writer()
next(writer)
for data in response['Body'].iter_chunks(BLOCK_SIZE):
writer.send(data)
return output_file
def compress_and_encrypt(
input_file: IOIter,
output_file: IOIter,
key_pair: Optional[bytes],
options: OptionsDict,
) -> bytes:
""" Read data from an open file descriptor, and write the compressed, encrypted data to another
file descriptor; compute the HMAC of the encrypted data to ensure integrity
:param input_file: an IOIter object to read plaintext data from
:param output_file: an IOIter object to write compressed ciphertext to
"""
key, nonce = (key_pair[:AES_KEY_SIZE], key_pair[AES_KEY_SIZE:]) if key_pair else (b'', b'')
compressobj = zlib.compressobj()
zip_fn: Callable[[bytes], bytes] = ( # type: ignore
compressobj.compress if options['use_compression'] else identity
)
encrypt_fn: Callable[[bytes], bytes] = (
Cipher(AES(key), CTR(nonce), backend=default_backend()).encryptor().update
if options['use_encryption'] else identity
)
hmac = HMAC(key, SHA256(), default_backend())
def last_block() -> Generator[Tuple[bytes, bool], None, None]:
yield (compressobj.flush(), False) if options['use_compression'] else (b'', False)
writer = output_file.writer(); next(writer)
logger.debug2('starting to compress')
for block, needs_compression in chain(zip(input_file.reader(), repeat(True)), last_block()):
if needs_compression:
block = zip_fn(block)
logger.debug2(f'zip_fn returned {len(block)} bytes')
block = encrypt_fn(block)
logger.debug2(f'encrypt_fn returned {len(block)} bytes')
if options['use_encryption']:
hmac.update(block)
writer.send(block)
if options['use_encryption']:
return hmac.finalize()
else:
return b''
def mock_open_streams():
class MockBytesIO(BytesIO):
def fileno(self): # make this work with fstat
return self
orig, new, diff = IOIter('/orig'), IOIter('/new'), IOIter('/diff')
with mock.patch('builtins.open'), \
mock.patch('backuppy.io.os.open'), \
mock.patch('backuppy.io.os.fdopen'), \
mock.patch('backuppy.io.os.stat'), \
mock.patch('backuppy.io.os.makedirs'), \
mock.patch('os.fstat') as mock_fstat, \
orig, new, diff:
mock_fstat.side_effect = lambda bio: mock.Mock(st_size=len(bio.
getvalue()))
orig.block_size = new.block_size = diff.block_size = 2
orig._fd = MockBytesIO(b'asdfasdfa')
new._fd = MockBytesIO()
diff._fd = MockBytesIO()
yield orig, new, diff
def get_manifest_keypair(
manifest_filename: str,
private_key_filename: str,
load: Callable[[str, IOIter], IOIter],
) -> bytes:
ts = manifest_filename.split('.', 1)[1]
with IOIter() as manifest_key:
# the key is not large enough to worry about chunked reads, so just do it all at once
load(MANIFEST_KEY_FILE.format(ts=ts), manifest_key)
manifest_key.fd.seek(0)
encrypted_key_pair = manifest_key.fd.read()
return decrypt_and_verify(encrypted_key_pair, private_key_filename)
def test_tmp_io_iter(fs):
with mock.patch(
'backuppy.io.io.BytesIO') as mock_bytes_io, IOIter() as tmp:
tmp._check_mtime()
assert mock_bytes_io.call_count == 1
with pytest.raises(BufferError):
tmp.uid
with pytest.raises(BufferError):
tmp.gid
with pytest.raises(BufferError):
tmp.mode
with pytest.raises(BufferError):
tmp.mtime
def test_validate_diffs(orig_data, new_data):
if not orig_data:
orig_data, new_data = generate_data()
print(orig_data)
print(new_data)
with IOIter() as orig, IOIter() as new, IOIter() as diff, IOIter(
) as newnew:
orig_writer = orig.writer()
next(orig_writer)
orig_writer.send(orig_data)
new_writer = new.writer()
next(new_writer)
new_writer.send(new_data)
compute_diff(orig, new, diff)
apply_diff(orig, diff, newnew)
new.fd.seek(0)
newnew.fd.seek(0)
assert new.fd.read() == newnew.fd.read()
def assert_backup_store_correct():
latest_manifest = get_latest_manifest()
manifest_conn = sqlite3.connect(latest_manifest)
manifest_conn.row_factory = sqlite3.Row
manifest_cursor = manifest_conn.cursor()
for path, history in test_file_history.items():
latest = history[-1]
manifest_cursor.execute(
'select * from manifest where abs_file_name=? order by commit_timestamp',
(os.path.abspath(latest.path),),
)
rows = manifest_cursor.fetchall()
if 'dont_back_me_up' in path:
assert len(rows) == 0
continue
else:
deduped_history = []
[deduped_history.append(i) for i in history if i not in deduped_history]
assert len(rows) == len(deduped_history)
for row in rows:
assert (row['sha'], row['mode']) in [(e.sha, e.mode) for e in deduped_history]
if latest.backup_path:
manifest_cursor.execute(
'select * from base_shas where sha=?',
(latest.sha,),
)
row = manifest_cursor.fetchone()
with IOIter(latest.backup_path) as n:
if not row or not row[1]:
assert n.fd.read() == latest.contents
else:
orig_file_path = path_join(BACKUP_DIR, row[1][:2], row[1][2:4], row[1][4:])
with IOIter(orig_file_path) as o, IOIter() as tmp:
apply_diff(o, n, tmp)
tmp.fd.seek(0)
assert tmp.fd.read() == latest.contents
def load(
self,
src: str,
dest: IOIter,
key_pair: Optional[bytes],
) -> IOIter:
""" Wrapper around the _load function that converts the SHA to a path """
src = sha_to_path(src)
with IOIter() as encrypted_load_file:
self._load(src, encrypted_load_file)
decrypt_and_unpack(encrypted_load_file, dest, key_pair,
self.options)
dest.fd.seek(0)
return dest
def apply_diff(orig_file: IOIter, diff_file: IOIter, new_file: IOIter) -> None:
""" Given an original file and a diff file, write out a new file with the diff applied
:param orig_file: an IOIter object whose contents are the "original" data
:param diff_file: an IOIter object whose contents are the diff to be applied
:param new_file: an IOIter object where the new file data will be written
"""
# The outer loop reads a chunk of data at a time; the inner loop parses
# the read chunk one step at a time and applies it
diff = b''
new_writer = new_file.writer()
next(new_writer)
orig_reader = orig_file.reader()
logger.debug2('applying diff')
for diff_chunk in diff_file.reader():
diff += diff_chunk
while diff:
# try to parse the next chunk; if we can't, break out of the loop to get more data
try:
diff_len_str, remainder = diff.split(SEPARATOR, 1)
except ValueError:
break
diff_len = int(diff_len_str)
if len(remainder) < diff_len:
break
try:
orig_block = next(orig_reader)
except StopIteration:
orig_block = b''
new_writer.send(bsdiff4.patch(orig_block, remainder[:diff_len]))
diff = remainder[diff_len:]
if diff:
raise DiffParseError(f'Un-parseable diff: {diff}') # type: ignore
def save(self, src: IOIter, dest: str, key_pair: bytes) -> bytes:
""" Wrapper around the _save function that converts the SHA to a path and does encryption
:param src: the file to save
:param dest: the name of the file to write to in the store
:param key_pair: an AES key + nonce to use to encrypt the file
:returns: the HMAC of the saved file
"""
dest = sha_to_path(dest)
# We compress and encrypt the file on the local file system, and then pass the encrypted
# file to the backup store to handle atomically
filename = path_join(get_scratch_dir(), dest)
with IOIter(filename) as encrypted_save_file:
signature = compress_and_encrypt(src, encrypted_save_file,
key_pair, self.options)
self._save(encrypted_save_file, dest) # test_f1_crash_file_save
os.remove(filename)
return signature
def _write_diff(
self,
abs_file_name: str,
new_sha: str,
curr_entry: ManifestEntry,
file_obj: IOIter,
dry_run: bool,
) -> ManifestEntry:
logger.info(f'Saving a diff for {abs_file_name}')
entry_data = self._find_existing_entry_data(new_sha)
# If the current entry is itself a diff, get its base; otherwise, this
# entry becomes the base
if entry_data:
key_pair, base_sha, base_key_pair = entry_data
elif curr_entry.base_sha:
key_pair = generate_key_pair(self.options)
base_sha = curr_entry.base_sha
base_key_pair = curr_entry.base_key_pair
else:
key_pair = generate_key_pair(self.options)
base_sha = curr_entry.sha
base_key_pair = curr_entry.key_pair
# compute a diff between the version we've previously backed up and the new version
new_entry = ManifestEntry(
abs_file_name,
new_sha,
base_sha,
file_obj.uid,
file_obj.gid,
file_obj.mode,
key_pair,
base_key_pair,
)
if not entry_data:
assert base_sha
with IOIter() as orig_file, IOIter() as diff_file:
orig_file = self.load(base_sha, orig_file, base_key_pair)
try:
fd_diff = compute_diff(
orig_file,
file_obj,
diff_file,
self.options['discard_diff_percentage'],
)
except DiffTooLargeException:
logger.info(
'The computed diff was too large; saving a copy instead.'
)
logger.info(
'(you can configure this threshold with the discard_diff_percentage option)'
)
file_obj.fd.seek(0)
return self._write_copy(abs_file_name, new_sha, file_obj,
False, dry_run)
new_entry.sha = new_sha
if not dry_run:
signature = self.save(fd_diff, new_entry.sha, key_pair)
new_entry.key_pair = key_pair + signature
return new_entry
def save_if_new(
self,
abs_file_name: str,
*,
dry_run: bool = False,
force_copy: bool = False,
) -> Optional[ManifestEntry]:
""" The main workhorse function; determine if a file has changed, and if so, back it up!
:param abs_file_name: the name of the file under consideration
:param dry_run: whether to actually save any data or not
:param force_copy: make a new copy of the file even if we could compute a diff instead
"""
curr_entry, new_entry = self.manifest.get_entry(abs_file_name), None
with IOIter(abs_file_name) as new_file:
new_sha = compute_sha(new_file)
# If the file hasn't been backed up before, or if it's been deleted previously, save a
# new copy; we make a copy here to ensure that the contents don't change while backing
# the file up, and that we have the correct sha
if force_copy or not curr_entry or not curr_entry.sha:
new_entry = self._write_copy(abs_file_name, new_sha, new_file,
force_copy, dry_run)
# If the file has been backed up, check to see if it's changed by comparing shas
elif new_sha != curr_entry.sha:
if regex_search_list(abs_file_name,
self.options['skip_diff_patterns']):
new_entry = self._write_copy(abs_file_name, new_sha,
new_file, False, dry_run)
else:
new_entry = self._write_diff(
abs_file_name,
new_sha,
curr_entry,
new_file,
dry_run,
)
# If the sha is the same but metadata on the file has changed, we just store the updated
# metadata
elif (new_file.uid != curr_entry.uid
or new_file.gid != curr_entry.gid
or new_file.mode != curr_entry.mode):
logger.info(f'Saving changed metadata for {abs_file_name}')
new_entry = ManifestEntry(
abs_file_name,
curr_entry.sha,
curr_entry.base_sha,
new_file.uid,
new_file.gid,
new_file.mode,
curr_entry.
key_pair, # NOTE: this is safe because the data has not changed!
curr_entry.base_key_pair,
)
else:
# we don't want to flood the log with all the files that haven't changed
logger.debug(f'{abs_file_name} is up to date!')
if new_entry and not dry_run:
self.manifest.insert_or_update(new_entry)
return new_entry # test_m2_crash_after_file_save
def test_load(mock_backup_store):
with IOIter('/restored_file') as output:
mock_backup_store._load('/foo', output)
with open('/restored_file') as f:
assert f.read() == 'old boring content'
def test_copy(mock_io_iter, foo_contents):
with mock_io_iter, IOIter('/bar') as copy:
io_copy(mock_io_iter, copy)
with open('/bar', 'rb') as f:
assert f.read() == foo_contents
def mock_io_iter(fs):
fake_filesystem.set_uid(1000)
fake_filesystem.set_gid(1000)
yield IOIter('/foo', block_size=2)
def _load(self, path: str, output_file: IOIter) -> IOIter:
abs_backup_path = path_join(self.backup_location, path)
logger.info(f'Reading {path} from {self.backup_location}')
with IOIter(abs_backup_path) as input_file:
io_copy(input_file, output_file)
return output_file
