189 lines
7.4 KiB
Python
189 lines
7.4 KiB
Python
# This file is part of Radicale Server - Calendar Server
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# Copyright © 2008 Nicolas Kandel
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# Copyright © 2008 Pascal Halter
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# Copyright © 2008-2016 Guillaume Ayoub
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#
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# This library is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Radicale. If not, see <http://www.gnu.org/licenses/>.
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"""
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Authentication management.
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Default is htpasswd authentication.
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Apache's htpasswd command (httpd.apache.org/docs/programs/htpasswd.html)
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manages a file for storing user credentials. It can encrypt passwords using
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different methods, e.g. BCRYPT, MD5-APR1 (a version of MD5 modified for
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Apache), SHA1, or by using the system's CRYPT routine. The CRYPT and SHA1
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encryption methods implemented by htpasswd are considered as insecure. MD5-APR1
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provides medium security as of 2015. Only BCRYPT can be considered secure by
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current standards.
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MD5-APR1-encrypted credentials can be written by all versions of htpasswd (it
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is the default, in fact), whereas BCRYPT requires htpasswd 2.4.x or newer.
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The `is_authenticated(user, password)` function provided by this module
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verifies the user-given credentials by parsing the htpasswd credential file
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pointed to by the ``htpasswd_filename`` configuration value while assuming
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the password encryption method specified via the ``htpasswd_encryption``
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configuration value.
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The following htpasswd password encrpytion methods are supported by Radicale
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out-of-the-box:
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- plain-text (created by htpasswd -p...) -- INSECURE
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- CRYPT (created by htpasswd -d...) -- INSECURE
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- SHA1 (created by htpasswd -s...) -- INSECURE
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When passlib (https://pypi.python.org/pypi/passlib) is importable, the
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following significantly more secure schemes are parsable by Radicale:
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- MD5-APR1 (htpasswd -m...) -- htpasswd's default method
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- BCRYPT (htpasswd -B...) -- Requires htpasswd 2.4.x
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"""
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import base64
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import functools
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import hashlib
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import os
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from importlib import import_module
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def load(configuration, logger):
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"""Load the authentication manager chosen in configuration."""
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auth_type = configuration.get("auth", "type")
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logger.debug("Authentication type is %s", auth_type)
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if auth_type == "None":
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return lambda user, password: True
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elif auth_type == "htpasswd":
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return Auth(configuration, logger).is_authenticated
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else:
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module = import_module(auth_type)
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return module.Auth(configuration, logger).is_authenticated
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class BaseAuth:
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def __init__(self, configuration, logger):
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self.configuration = configuration
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self.logger = logger
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def is_authenticated(self, user, password):
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"""Validate credentials.
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Iterate through htpasswd credential file until user matches, extract
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hash (encrypted password) and check hash against user-given password,
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using the method specified in the Radicale config.
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"""
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raise NotImplementedError
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class Auth(BaseAuth):
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def __init__(self, configuration, logger):
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super().__init__(configuration, logger)
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self.filename = os.path.expanduser(
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configuration.get("auth", "htpasswd_filename"))
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self.encryption = configuration.get("auth", "htpasswd_encryption")
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if self.encryption == "ssha":
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self.verify = self._ssha
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elif self.encryption == "sha1":
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self.verify = self._sha1
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elif self.encryption == "plain":
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self.verify = self._plain
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elif self.encryption == "md5":
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try:
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from passlib.hash import apr_md5_crypt
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except ImportError:
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raise RuntimeError(
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"The htpasswd encryption method 'md5' requires "
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"the passlib module.")
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self.verify = functools.partial(self._md5apr1, apr_md5_crypt)
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elif self.encryption == "bcrypt":
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try:
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from passlib.hash import bcrypt
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except ImportError:
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raise RuntimeError(
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"The htpasswd encryption method 'bcrypt' requires "
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"the passlib module with bcrypt support.")
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# A call to `encrypt` raises passlib.exc.MissingBackendError with a
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# good error message if bcrypt backend is not available. Trigger
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# this here.
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bcrypt.encrypt("test-bcrypt-backend")
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self.verify = functools.partial(self._bcrypt, bcrypt)
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elif self.encryption == "crypt":
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try:
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import crypt
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except ImportError:
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raise RuntimeError(
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"The htpasswd encryption method 'crypt' requires "
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"the crypt() system support.")
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self.verify = functools.partial(self._crypt, crypt)
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else:
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raise RuntimeError(
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"The htpasswd encryption method '%s' is not "
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"supported." % self.encryption)
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def _plain(self, hash_value, password):
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"""Check if ``hash_value`` and ``password`` match, plain method."""
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return hash_value == password
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def _crypt(self, crypt, hash_value, password):
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"""Check if ``hash_value`` and ``password`` match, crypt method."""
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return crypt.crypt(password, hash_value) == hash_value
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def _sha1(self, hash_value, password):
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"""Check if ``hash_value`` and ``password`` match, sha1 method."""
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hash_value = hash_value.replace("{SHA}", "").encode("ascii")
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password = password.encode(self.configuration.get("encoding", "stock"))
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sha1 = hashlib.sha1()
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sha1.update(password)
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return sha1.digest() == base64.b64decode(hash_value)
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def _ssha(self, hash_value, password):
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"""Check if ``hash_value`` and ``password`` match, salted sha1 method.
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This method is not directly supported by htpasswd, but it can be
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written with e.g. openssl, and nginx can parse it.
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"""
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hash_value = hash_value.replace(
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"{SSHA}", "").encode("ascii").decode("base64")
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password = password.encode(self.configuration.get("encoding", "stock"))
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hash_value = hash_value[:20]
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salt_value = hash_value[20:]
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sha1 = hashlib.sha1()
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sha1.update(password)
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sha1.update(salt_value)
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return sha1.digest() == hash_value
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def _bcrypt(self, bcrypt, hash_value, password):
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return bcrypt.verify(password, hash_value)
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def _md5apr1(self, md5_apr1, hash_value, password):
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return md5_apr1.verify(password, hash_value)
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def is_authenticated(self, user, password):
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# The content of the file is not cached because reading is generally a
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# very cheap operation, and it's useful to get live updates of the
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# htpasswd file.
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with open(self.filename) as fd:
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for line in fd:
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line = line.strip()
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if line:
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login, hash_value = line.split(":")
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if login == user:
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return self.verify(hash_value, password)
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return False
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