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)
)
)