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# SecretStorage module for Python
# Access passwords using the SecretService DBus API
# Author: Dmitry Shachnev, 2013
# License: BSD
"""This module provides some utility functions, but these shouldn't
normally be used by external applications."""
import dbus
import os
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
from cryptography.utils import int_from_bytes
BUS_NAME = 'org.freedesktop.secrets'
SERVICE_IFACE = SS_PREFIX + 'Service'
class InterfaceWrapper(dbus.Interface):
"""Wraps :cls:`dbus.Interface` class and replaces some D-Bus exceptions
with :doc:`SecretStorage exceptions <exceptions>`."""
def catch_errors(self, function_in):
def function_out(*args, **kwargs):
try:
return function_in(*args, **kwargs)
except dbus.exceptions.DBusException as e:
if e.get_dbus_name() == DBUS_UNKNOWN_METHOD:
raise ItemNotFoundException('Item does not exist!')
if e.get_dbus_name() == DBUS_NO_SUCH_OBJECT:
raise ItemNotFoundException(e.get_dbus_message())
if e.get_dbus_name() in (DBUS_NO_REPLY, DBUS_NOT_SUPPORTED):
raise SecretServiceNotAvailableException(
e.get_dbus_message())
raise
return function_out
def __getattr__(self, attribute):
result = dbus.Interface.__getattr__(self, attribute)
if callable(result):
result = self.catch_errors(result)
return result
def bus_get_object(bus, object_path, service_name=None):
"""A wrapper around :meth:`SessionBus.get_object` that raises
:exc:`~secretstorage.exceptions.SecretServiceNotAvailableException`
when appropriate."""
name = service_name or BUS_NAME
try:
return bus.get_object(name, object_path, introspect=False)
except dbus.exceptions.DBusException as e:
if e.get_dbus_name() in (DBUS_SERVICE_UNKNOWN, DBUS_EXEC_FAILED,
DBUS_NO_REPLY):
raise SecretServiceNotAvailableException(e.get_dbus_message())
raise
def open_session(bus):
"""Returns a new Secret Service session."""
service_obj = bus_get_object(bus, SS_PATH)
service_iface = dbus.Interface(service_obj, SS_PREFIX+'Service')
session = Session()
try:
output, result = service_iface.OpenSession(
ALGORITHM_DH,
dbus.ByteArray(int_to_bytes(session.my_public_key)),
signature='sv'
)
except dbus.exceptions.DBusException as e:
if e.get_dbus_name() != DBUS_NOT_SUPPORTED:
raise
output, result = service_iface.OpenSession(
ALGORITHM_PLAIN,
'',
signature='sv'
)
session.encrypted = False
else:
output = int_from_bytes(bytearray(output), 'big')
session.set_server_public_key(output)
session.object_path = result
return session
def format_secret(session, secret, content_type):
"""Formats `secret` to make possible to pass it to the
Secret Service API."""
if not isinstance(secret, bytes):
secret = secret.encode('utf-8')
if not session.encrypted:
return dbus.Struct((session.object_path, '',
dbus.ByteArray(secret), content_type))
# PKCS-7 style padding
padding = 0x10 - (len(secret) & 0xf)
secret += bytes(bytearray((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 dbus.Struct((
session.object_path,
dbus.Array(aes_iv),
dbus.Array(bytearray(encrypted_secret)),
content_type
))
def exec_prompt(bus, prompt, callback):
"""Executes the given `prompt`, when complete calls `callback`
function with two arguments: a boolean representing whether the
operation was dismissed and a list of unlocked item paths. A main
loop should be running and registered for this function to work."""
prompt_obj = bus_get_object(bus, prompt)
prompt_iface = dbus.Interface(prompt_obj, SS_PREFIX+'Prompt')
prompt_iface.Prompt('', signature='s')
def new_callback(dismissed, unlocked):
if isinstance(unlocked, dbus.Array):
unlocked = list(unlocked)
callback(bool(dismissed), unlocked)
prompt_iface.connect_to_signal('Completed', new_callback)
def exec_prompt_glib(bus, prompt):
"""Like :func:`exec_prompt`, but synchronous (uses loop from GLib
API). Returns (*dismissed*, *unlocked*) tuple."""
from gi.repository import GLib
loop = GLib.MainLoop()
result = []
def callback(dismissed, unlocked):
result.append(dismissed)
result.append(unlocked)
loop.quit()
exec_prompt(bus, prompt, callback)
loop.run()
return result[0], result[1]
def exec_prompt_qt(bus, prompt):
"""Like :func:`exec_prompt`, but synchronous (uses loop from PyQt5
API). Returns (*dismissed*, *unlocked*) tuple."""
from PyQt5.QtCore import QCoreApplication
app = QCoreApplication([])
result = []
def callback(dismissed, unlocked):
result.append(dismissed)
result.append(unlocked)
app.quit()
exec_prompt(bus, prompt, callback)
app.exec_()
return result[0], result[1]
def unlock_objects(bus, paths, callback=None):
"""Requests unlocking objects specified in `paths`. If `callback`
is specified, calls it when unlocking is complete (see
:func:`exec_prompt` description for details).
Otherwise, uses the loop from GLib API and returns a boolean
representing whether the operation was dismissed.
.. versionadded:: 2.1.2"""
service_obj = bus_get_object(bus, SS_PATH)
service_iface = InterfaceWrapper(service_obj, SERVICE_IFACE)
unlocked_paths, prompt = service_iface.Unlock(paths, signature='ao')
unlocked_paths = list(unlocked_paths) # Convert from dbus.Array
if len(prompt) > 1:
if callback:
exec_prompt(bus, prompt, callback)
else:
return exec_prompt_glib(bus, prompt)[0]
elif callback:
# We still need to call it.
callback(False, unlocked_paths)
def to_unicode(string):
"""Converts D-Bus string to unicode string."""
try:
# For Python 2
return unicode(string)
except NameError:
# For Python 3
return str(string)
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