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# SecretStorage module for Python
# Access passwords using the SecretService DBus API
# Author: Dmitry Shachnev, 2013-2018
# License: 3-clause BSD, see LICENSE file
"""This module provides some utility functions, but these shouldn't
normally be used by external applications."""
import os
from typing import Any, List, Tuple
from jeepney import (
DBusAddress, DBusErrorResponse, MatchRule, Message, MessageType,
new_method_call, Properties,
)
from jeepney.io.blocking import DBusConnection
from secretstorage.defines import DBUS_UNKNOWN_METHOD, DBUS_NO_SUCH_OBJECT, \
DBUS_SERVICE_UNKNOWN, DBUS_NO_REPLY, DBUS_NOT_SUPPORTED, DBUS_EXEC_FAILED, \
SS_PATH, SS_PREFIX, ALGORITHM_DH, ALGORITHM_PLAIN
from secretstorage.dhcrypto import Session, int_to_bytes
from secretstorage.exceptions import ItemNotFoundException, \
SecretServiceNotAvailableException
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.backends import default_backend
BUS_NAME = 'org.freedesktop.secrets'
SERVICE_IFACE = SS_PREFIX + 'Service'
PROMPT_IFACE = SS_PREFIX + 'Prompt'
class DBusAddressWrapper(DBusAddress): # type: ignore
"""A wrapper class around :class:`jeepney.wrappers.DBusAddress`
that adds some additional methods for calling and working with
properties, and converts error responses to SecretStorage
exceptions.
.. versionadded:: 3.0
"""
def __init__(self, path: str, interface: str,
connection: DBusConnection) -> None:
DBusAddress.__init__(self, path, BUS_NAME, interface)
self._connection = connection
def send_and_get_reply(self, msg: Message) -> Any:
try:
return self._connection.send_and_get_reply(msg, unwrap=True)
except DBusErrorResponse as resp:
if resp.name in (DBUS_UNKNOWN_METHOD, DBUS_NO_SUCH_OBJECT):
raise ItemNotFoundException('Item does not exist!') from resp
elif resp.name in (DBUS_SERVICE_UNKNOWN, DBUS_EXEC_FAILED,
DBUS_NO_REPLY):
data = resp.data
if isinstance(data, tuple):
data = data[0]
raise SecretServiceNotAvailableException(data) from resp
raise
def call(self, method: str, signature: str, *body: Any) -> Any:
msg = new_method_call(self, method, signature, body)
return self.send_and_get_reply(msg)
def get_property(self, name: str) -> Any:
msg = Properties(self).get(name)
(signature, value), = self.send_and_get_reply(msg)
return value
def set_property(self, name: str, signature: str, value: Any) -> None:
msg = Properties(self).set(name, signature, value)
self.send_and_get_reply(msg)
def open_session(connection: DBusConnection) -> Session:
"""Returns a new Secret Service session."""
service = DBusAddressWrapper(SS_PATH, SERVICE_IFACE, connection)
session = Session()
try:
output, result = service.call('OpenSession', 'sv',
ALGORITHM_DH,
('ay', int_to_bytes(session.my_public_key)))
except DBusErrorResponse as resp:
if resp.name != DBUS_NOT_SUPPORTED:
raise
output, result = service.call('OpenSession', 'sv',
ALGORITHM_PLAIN,
('s', ''))
session.encrypted = False
else:
signature, value = output
assert signature == 'ay'
key = int.from_bytes(value, 'big')
session.set_server_public_key(key)
session.object_path = result
return session
def format_secret(session: Session, secret: bytes,
content_type: str) -> Tuple[str, bytes, bytes, str]:
"""Formats `secret` to make possible to pass it to the
Secret Service API."""
if isinstance(secret, str):
secret = secret.encode('utf-8')
elif not isinstance(secret, bytes):
raise TypeError('secret must be bytes')
assert session.object_path is not None
if not session.encrypted:
return (session.object_path, b'', secret, content_type)
assert session.aes_key is not None
# PKCS-7 style padding
padding = 0x10 - (len(secret) & 0xf)
secret += bytes((padding,) * padding)
aes_iv = os.urandom(0x10)
aes = algorithms.AES(session.aes_key)
encryptor = Cipher(aes, modes.CBC(aes_iv), default_backend()).encryptor()
encrypted_secret = encryptor.update(secret) + encryptor.finalize()
return (
session.object_path,
aes_iv,
encrypted_secret,
content_type
)
def exec_prompt(connection: DBusConnection,
prompt_path: str) -> Tuple[bool, List[str]]:
"""Executes the prompt in a blocking mode.
:returns: a tuple; the first element is a boolean value showing
whether the operation was dismissed, the second element
is a list of unlocked object paths
"""
prompt = DBusAddressWrapper(prompt_path, PROMPT_IFACE, connection)
rule = MatchRule(
path=prompt_path,
interface=PROMPT_IFACE,
member='Completed',
type=MessageType.signal,
)
with connection.filter(rule) as signals:
prompt.call('Prompt', 's', '')
dismissed, result = connection.recv_until_filtered(signals).body
assert dismissed is not None
assert result is not None
return dismissed, result
def unlock_objects(connection: DBusConnection, paths: List[str]) -> bool:
"""Requests unlocking objects specified in `paths`.
Returns a boolean representing whether the operation was dismissed.
.. versionadded:: 2.1.2"""
service = DBusAddressWrapper(SS_PATH, SERVICE_IFACE, connection)
unlocked_paths, prompt = service.call('Unlock', 'ao', paths)
if len(prompt) > 1:
dismissed, (signature, unlocked) = exec_prompt(connection, prompt)
assert signature == 'ao'
return dismissed
return False
def add_match_rules(connection: DBusConnection) -> None:
"""Adds match rules for the given connection.
Currently it matches all messages from the Prompt interface, as the
mock service (unlike GNOME Keyring) does not specify the signal
destination.
.. versionadded:: 3.1
"""
rule = MatchRule(sender=BUS_NAME, interface=PROMPT_IFACE)
dbus = DBusAddressWrapper(path='/org/freedesktop/DBus',
interface='org.freedesktop.DBus',
connection=connection)
dbus.bus_name = 'org.freedesktop.DBus'
dbus.call('AddMatch', 's', rule.serialise())
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