forked-synapse/synapse/util/ldap_auth_provider.py
Erik Johnston 850b103b36 Implement pluggable password auth
Allows delegating the password auth to an external module. This also
moves the LDAP auth to using this system, allowing it to be removed from
the synapse tree entirely in the future.
2016-10-03 10:36:40 +01:00

369 lines
12 KiB
Python

from twisted.internet import defer
from synapse.config._base import ConfigError
from synapse.types import UserID
import ldap3
import ldap3.core.exceptions
import logging
try:
import ldap3
import ldap3.core.exceptions
except ImportError:
ldap3 = None
pass
logger = logging.getLogger(__name__)
class LDAPMode(object):
SIMPLE = "simple",
SEARCH = "search",
LIST = (SIMPLE, SEARCH)
class LdapAuthProvider(object):
__version__ = "0.1"
def __init__(self, config, account_handler):
self.account_handler = account_handler
if not ldap3:
raise RuntimeError(
'Missing ldap3 library. This is required for LDAP Authentication.'
)
self.ldap_mode = config.mode
self.ldap_uri = config.uri
self.ldap_start_tls = config.start_tls
self.ldap_base = config.base
self.ldap_attributes = config.attributes
if self.ldap_mode == LDAPMode.SEARCH:
self.ldap_bind_dn = config.bind_dn
self.ldap_bind_password = config.bind_password
self.ldap_filter = config.filter
@defer.inlineCallbacks
def check_password(self, user_id, password):
""" Attempt to authenticate a user against an LDAP Server
and register an account if none exists.
Returns:
True if authentication against LDAP was successful
"""
localpart = UserID.from_string(user_id).localpart
try:
server = ldap3.Server(self.ldap_uri)
logger.debug(
"Attempting LDAP connection with %s",
self.ldap_uri
)
if self.ldap_mode == LDAPMode.SIMPLE:
result, conn = self._ldap_simple_bind(
server=server, localpart=localpart, password=password
)
logger.debug(
'LDAP authentication method simple bind returned: %s (conn: %s)',
result,
conn
)
if not result:
defer.returnValue(False)
elif self.ldap_mode == LDAPMode.SEARCH:
result, conn = self._ldap_authenticated_search(
server=server, localpart=localpart, password=password
)
logger.debug(
'LDAP auth method authenticated search returned: %s (conn: %s)',
result,
conn
)
if not result:
defer.returnValue(False)
else:
raise RuntimeError(
'Invalid LDAP mode specified: {mode}'.format(
mode=self.ldap_mode
)
)
try:
logger.info(
"User authenticated against LDAP server: %s",
conn
)
except NameError:
logger.warn(
"Authentication method yielded no LDAP connection, aborting!"
)
defer.returnValue(False)
# check if user with user_id exists
if (yield self.account_handler.check_user_exists(user_id)):
# exists, authentication complete
conn.unbind()
defer.returnValue(True)
else:
# does not exist, fetch metadata for account creation from
# existing ldap connection
query = "({prop}={value})".format(
prop=self.ldap_attributes['uid'],
value=localpart
)
if self.ldap_mode == LDAPMode.SEARCH and self.ldap_filter:
query = "(&{filter}{user_filter})".format(
filter=query,
user_filter=self.ldap_filter
)
logger.debug(
"ldap registration filter: %s",
query
)
conn.search(
search_base=self.ldap_base,
search_filter=query,
attributes=[
self.ldap_attributes['name'],
self.ldap_attributes['mail']
]
)
if len(conn.response) == 1:
attrs = conn.response[0]['attributes']
mail = attrs[self.ldap_attributes['mail']][0]
name = attrs[self.ldap_attributes['name']][0]
# create account
user_id, access_token = (
yield self.account_handler.register(localpart=localpart)
)
# TODO: bind email, set displayname with data from ldap directory
logger.info(
"Registration based on LDAP data was successful: %d: %s (%s, %)",
user_id,
localpart,
name,
mail
)
defer.returnValue(True)
else:
if len(conn.response) == 0:
logger.warn("LDAP registration failed, no result.")
else:
logger.warn(
"LDAP registration failed, too many results (%s)",
len(conn.response)
)
defer.returnValue(False)
defer.returnValue(False)
except ldap3.core.exceptions.LDAPException as e:
logger.warn("Error during ldap authentication: %s", e)
defer.returnValue(False)
@staticmethod
def parse_config(config):
class _LdapConfig(object):
pass
ldap_config = _LdapConfig()
ldap_config.enabled = config.get("enabled", False)
ldap_config.mode = LDAPMode.SIMPLE
# verify config sanity
_require_keys(config, [
"uri",
"base",
"attributes",
])
ldap_config.uri = config["uri"]
ldap_config.start_tls = config.get("start_tls", False)
ldap_config.base = config["base"]
ldap_config.attributes = config["attributes"]
if "bind_dn" in config:
ldap_config.mode = LDAPMode.SEARCH
_require_keys(config, [
"bind_dn",
"bind_password",
])
ldap_config.bind_dn = config["bind_dn"]
ldap_config.bind_password = config["bind_password"]
ldap_config.filter = config.get("filter", None)
# verify attribute lookup
_require_keys(config['attributes'], [
"uid",
"name",
"mail",
])
return ldap_config
def _ldap_simple_bind(self, server, localpart, password):
""" Attempt a simple bind with the credentials
given by the user against the LDAP server.
Returns True, LDAP3Connection
if the bind was successful
Returns False, None
if an error occured
"""
try:
# bind with the the local users ldap credentials
bind_dn = "{prop}={value},{base}".format(
prop=self.ldap_attributes['uid'],
value=localpart,
base=self.ldap_base
)
conn = ldap3.Connection(server, bind_dn, password)
logger.debug(
"Established LDAP connection in simple bind mode: %s",
conn
)
if self.ldap_start_tls:
conn.start_tls()
logger.debug(
"Upgraded LDAP connection in simple bind mode through StartTLS: %s",
conn
)
if conn.bind():
# GOOD: bind okay
logger.debug("LDAP Bind successful in simple bind mode.")
return True, conn
# BAD: bind failed
logger.info(
"Binding against LDAP failed for '%s' failed: %s",
localpart, conn.result['description']
)
conn.unbind()
return False, None
except ldap3.core.exceptions.LDAPException as e:
logger.warn("Error during LDAP authentication: %s", e)
return False, None
def _ldap_authenticated_search(self, server, localpart, password):
""" Attempt to login with the preconfigured bind_dn
and then continue searching and filtering within
the base_dn
Returns (True, LDAP3Connection)
if a single matching DN within the base was found
that matched the filter expression, and with which
a successful bind was achieved
The LDAP3Connection returned is the instance that was used to
verify the password not the one using the configured bind_dn.
Returns (False, None)
if an error occured
"""
try:
conn = ldap3.Connection(
server,
self.ldap_bind_dn,
self.ldap_bind_password
)
logger.debug(
"Established LDAP connection in search mode: %s",
conn
)
if self.ldap_start_tls:
conn.start_tls()
logger.debug(
"Upgraded LDAP connection in search mode through StartTLS: %s",
conn
)
if not conn.bind():
logger.warn(
"Binding against LDAP with `bind_dn` failed: %s",
conn.result['description']
)
conn.unbind()
return False, None
# construct search_filter like (uid=localpart)
query = "({prop}={value})".format(
prop=self.ldap_attributes['uid'],
value=localpart
)
if self.ldap_filter:
# combine with the AND expression
query = "(&{query}{filter})".format(
query=query,
filter=self.ldap_filter
)
logger.debug(
"LDAP search filter: %s",
query
)
conn.search(
search_base=self.ldap_base,
search_filter=query
)
if len(conn.response) == 1:
# GOOD: found exactly one result
user_dn = conn.response[0]['dn']
logger.debug('LDAP search found dn: %s', user_dn)
# unbind and simple bind with user_dn to verify the password
# Note: do not use rebind(), for some reason it did not verify
# the password for me!
conn.unbind()
return self._ldap_simple_bind(server, localpart, password)
else:
# BAD: found 0 or > 1 results, abort!
if len(conn.response) == 0:
logger.info(
"LDAP search returned no results for '%s'",
localpart
)
else:
logger.info(
"LDAP search returned too many (%s) results for '%s'",
len(conn.response), localpart
)
conn.unbind()
return False, None
except ldap3.core.exceptions.LDAPException as e:
logger.warn("Error during LDAP authentication: %s", e)
return False, None
def _require_keys(config, required):
missing = [key for key in required if key not in config]
if missing:
raise ConfigError(
"LDAP enabled but missing required config values: {}".format(
", ".join(missing)
)
)