radicale_plugins/radicale/auth.py

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2018-04-10 17:57:45 +00:00
# This file is part of Radicale Server - Calendar Server
# Copyright © 2008 Nicolas Kandel
# Copyright © 2008 Pascal Halter
# Copyright © 2008-2017 Guillaume Ayoub
#
# This library is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Radicale. If not, see <http://www.gnu.org/licenses/>.
"""
Authentication management.
Default is htpasswd authentication.
Apache's htpasswd command (httpd.apache.org/docs/programs/htpasswd.html)
manages a file for storing user credentials. It can encrypt passwords using
different methods, e.g. BCRYPT, MD5-APR1 (a version of MD5 modified for
Apache), SHA1, or by using the system's CRYPT routine. The CRYPT and SHA1
encryption methods implemented by htpasswd are considered as insecure. MD5-APR1
provides medium security as of 2015. Only BCRYPT can be considered secure by
current standards.
MD5-APR1-encrypted credentials can be written by all versions of htpasswd (it
is the default, in fact), whereas BCRYPT requires htpasswd 2.4.x or newer.
The `is_authenticated(user, password)` function provided by this module
verifies the user-given credentials by parsing the htpasswd credential file
pointed to by the ``htpasswd_filename`` configuration value while assuming
the password encryption method specified via the ``htpasswd_encryption``
configuration value.
The following htpasswd password encrpytion methods are supported by Radicale
out-of-the-box:
- plain-text (created by htpasswd -p...) -- INSECURE
- CRYPT (created by htpasswd -d...) -- INSECURE
- SHA1 (created by htpasswd -s...) -- INSECURE
When passlib (https://pypi.python.org/pypi/passlib) is importable, the
following significantly more secure schemes are parsable by Radicale:
- MD5-APR1 (htpasswd -m...) -- htpasswd's default method
- BCRYPT (htpasswd -B...) -- Requires htpasswd 2.4.x
"""
import base64
import functools
import hashlib
import hmac
import os
from importlib import import_module
INTERNAL_TYPES = ("None", "none", "remote_user", "http_x_remote_user",
"htpasswd")
def load(configuration, logger):
"""Load the authentication manager chosen in configuration."""
auth_type = configuration.get("auth", "type")
if auth_type in ("None", "none"): # DEPRECATED: use "none"
class_ = NoneAuth
elif auth_type == "remote_user":
class_ = RemoteUserAuth
elif auth_type == "http_x_remote_user":
class_ = HttpXRemoteUserAuth
elif auth_type == "htpasswd":
class_ = Auth
else:
try:
class_ = import_module(auth_type).Auth
except Exception as e:
raise RuntimeError("Failed to load authentication module %r: %s" %
(auth_type, e)) from e
logger.info("Authentication type is %r", auth_type)
return class_(configuration, logger)
class BaseAuth:
def __init__(self, configuration, logger):
self.configuration = configuration
self.logger = logger
def get_external_login(self, environ):
"""Optionally provide the login and password externally.
``environ`` a dict with the WSGI environment
If ``()`` is returned, Radicale handles HTTP authentication.
Otherwise, returns a tuple ``(login, password)``. For anonymous users
``login`` must be ``""``.
"""
return ()
def is_authenticated2(self, login, user, password):
"""Validate credentials.
``login`` the login name
``user`` the user from ``map_login_to_user(login)``.
``password`` the login password
"""
return self.is_authenticated(user, password)
def is_authenticated(self, user, password):
"""Validate credentials.
DEPRECATED: use ``is_authenticated2`` instead
"""
raise NotImplementedError
def map_login_to_user(self, login):
"""Map login name to internal user.
``login`` the login name, ``""`` for anonymous users
Returns a string with the user name.
If a login can't be mapped to an user, return ``login`` and
return ``False`` in ``is_authenticated2(...)``.
"""
return login
class NoneAuth(BaseAuth):
def is_authenticated(self, user, password):
return True
class Auth(BaseAuth):
def __init__(self, configuration, logger):
super().__init__(configuration, logger)
self.filename = os.path.expanduser(
configuration.get("auth", "htpasswd_filename"))
self.encryption = configuration.get("auth", "htpasswd_encryption")
if self.encryption == "ssha":
self.verify = self._ssha
elif self.encryption == "sha1":
self.verify = self._sha1
elif self.encryption == "plain":
self.verify = self._plain
elif self.encryption == "md5":
try:
from passlib.hash import apr_md5_crypt
except ImportError as e:
raise RuntimeError(
"The htpasswd encryption method 'md5' requires "
"the passlib module.") from e
self.verify = functools.partial(self._md5apr1, apr_md5_crypt)
elif self.encryption == "bcrypt":
try:
from passlib.hash import bcrypt
except ImportError as e:
raise RuntimeError(
"The htpasswd encryption method 'bcrypt' requires "
"the passlib module with bcrypt support.") from e
# A call to `encrypt` raises passlib.exc.MissingBackendError with a
# good error message if bcrypt backend is not available. Trigger
# this here.
bcrypt.encrypt("test-bcrypt-backend")
self.verify = functools.partial(self._bcrypt, bcrypt)
elif self.encryption == "crypt":
try:
import crypt
except ImportError as e:
raise RuntimeError(
"The htpasswd encryption method 'crypt' requires "
"the crypt() system support.") from e
self.verify = functools.partial(self._crypt, crypt)
else:
raise RuntimeError(
"The htpasswd encryption method %r is not "
"supported." % self.encryption)
def _plain(self, hash_value, password):
"""Check if ``hash_value`` and ``password`` match, plain method."""
return hmac.compare_digest(hash_value, password)
def _crypt(self, crypt, hash_value, password):
"""Check if ``hash_value`` and ``password`` match, crypt method."""
hash_value = hash_value.strip()
return hmac.compare_digest(crypt.crypt(password, hash_value),
hash_value)
def _sha1(self, hash_value, password):
"""Check if ``hash_value`` and ``password`` match, sha1 method."""
hash_value = base64.b64decode(hash_value.strip().replace(
"{SHA}", "").encode("ascii"))
password = password.encode(self.configuration.get("encoding", "stock"))
sha1 = hashlib.sha1()
sha1.update(password)
return hmac.compare_digest(sha1.digest(), hash_value)
def _ssha(self, hash_value, password):
"""Check if ``hash_value`` and ``password`` match, salted sha1 method.
This method is not directly supported by htpasswd, but it can be
written with e.g. openssl, and nginx can parse it.
"""
hash_value = base64.b64decode(hash_value.strip().replace(
"{SSHA}", "").encode("ascii"))
password = password.encode(self.configuration.get("encoding", "stock"))
salt_value = hash_value[20:]
hash_value = hash_value[:20]
sha1 = hashlib.sha1()
sha1.update(password)
sha1.update(salt_value)
return hmac.compare_digest(sha1.digest(), hash_value)
def _bcrypt(self, bcrypt, hash_value, password):
hash_value = hash_value.strip()
return bcrypt.verify(password, hash_value)
def _md5apr1(self, md5_apr1, hash_value, password):
hash_value = hash_value.strip()
return md5_apr1.verify(password, hash_value)
def is_authenticated(self, user, password):
"""Validate credentials.
Iterate through htpasswd credential file until user matches, extract
hash (encrypted password) and check hash against user-given password,
using the method specified in the Radicale config.
The content of the file is not cached because reading is generally a
very cheap operation, and it's useful to get live updates of the
htpasswd file.
"""
try:
with open(self.filename) as f:
for line in f:
line = line.rstrip("\n")
if line.lstrip() and not line.lstrip().startswith("#"):
try:
login, hash_value = line.split(":", maxsplit=1)
# Always compare both login and password to avoid
# timing attacks, see #591.
login_ok = hmac.compare_digest(login, user)
password_ok = self.verify(hash_value, password)
if login_ok and password_ok:
return True
except ValueError as e:
raise RuntimeError("Invalid htpasswd file %r: %s" %
(self.filename, e)) from e
except OSError as e:
raise RuntimeError("Failed to load htpasswd file %r: %s" %
(self.filename, e)) from e
return False
class RemoteUserAuth(NoneAuth):
def get_external_login(self, environ):
return environ.get("REMOTE_USER", ""), ""
class HttpXRemoteUserAuth(NoneAuth):
def get_external_login(self, environ):
return environ.get("HTTP_X_REMOTE_USER", ""), ""