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ldap_.py
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ldap_.py
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"""LDAP authentication plugin for pypicloud."""
import logging
from collections import namedtuple
from functools import wraps
from pyramid.settings import asbool, aslist
from pypicloud.util import TimedCache
from .base import IAccessBackend
from .config import ConfigAccessBackend
try:
import ldap
except ImportError as e: # pragma: no cover
raise ImportError(
"You must 'pip install pypicloud[ldap]' before using ldap as the "
"authentication backend."
) from e
LOG = logging.getLogger(__name__)
def reconnect(func):
"""
If the LDAP connection dies underneath us, recreate it
"""
@wraps(func)
def _reconnect(self, *args, **kwargs):
"""
Inner wrap function to reconnect on failure
"""
try:
return func(self, *args, **kwargs)
except ldap.LDAPError:
self.connect()
return func(self, *args, **kwargs)
return _reconnect
User = namedtuple("User", ["username", "dn", "is_admin"])
class LDAP(object):
"""Handles interactions with the remote LDAP server"""
def __init__(
self,
admin_field,
admin_group_dn,
admin_value,
base_dn,
cache_time,
service_dn,
service_password,
service_username,
url,
user_search_filter,
user_dn_format,
ignore_cert,
ignore_referrals,
ignore_multiple_results,
):
self._url = url
self._service_dn = service_dn
self._service_password = service_password
self._base_dn = base_dn
self._user_search_filter = user_search_filter
self._user_dn_format = user_dn_format
if user_dn_format is not None:
if base_dn is not None or user_search_filter is not None:
raise ValueError(
"Cannot use user_dn_format with base_dn " "and user_search_filter"
)
else:
if base_dn is None or user_search_filter is None:
raise ValueError(
"Must provide user_dn_format or both base_dn "
"and user_search_filter"
)
self._admin_field = admin_field
self._admin_group_dn = admin_group_dn
if admin_group_dn and not self._user_dn_format:
raise ValueError(
"ldap.admin_group_dn must be used with ldap.user_dn_format"
)
self._admin_value = set(admin_value)
self._server = None
if cache_time is not None:
cache_time = int(cache_time)
self._cache = TimedCache(cache_time, self._fetch_user)
if service_username is not None:
self._cache.set_expire(
service_username, User(service_username, service_dn, True), None
)
self._ignore_cert = ignore_cert
self._ignore_referrals = ignore_referrals
self._ignore_multiple_results = ignore_multiple_results
self._admin_member_type = None
def connect(self):
"""Initializes the python-ldap module and does the initial bind"""
if self._ignore_cert:
ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_NEVER)
if self._ignore_referrals:
ldap.set_option(ldap.OPT_REFERRALS, ldap.OPT_OFF)
LOG.debug("LDAP connecting to %s", self._url)
self._server = ldap.initialize(self._url, bytes_mode=False)
self._bind_to_service()
@property
def admin_member_type(self):
if self._admin_member_type is None:
LOG.debug("Fetching admin group %s", self._admin_group_dn)
try:
results = self._server.search_s(
self._admin_group_dn, ldap.SCOPE_BASE, attrlist=["objectClass"]
)
except ldap.NO_SUCH_OBJECT as e:
LOG.debug("NO_SUCH_OBJECT %s", e)
return "member"
dn, attributes = results[0]
classes = [self._decode_attribute(x) for x in attributes["objectClass"]]
if "groupOfUniqueNames" in classes:
self._admin_member_type = "uniqueMember"
else:
self._admin_member_type = "member"
return self._admin_member_type
def _bind_to_service(self):
"""Bind to the service account or anonymous"""
if self._service_dn:
# bind with the service_dn
self._server.simple_bind_s(self._service_dn, self._service_password)
else:
# force a connection without binding
self._server.whoami_s()
@reconnect
def test_connection(self):
"""Binds to service. Will throw if bad connection"""
self._bind_to_service()
@reconnect
def _fetch_user(self, username):
"""Fetch a user entry from the LDAP server"""
LOG.debug("LDAP fetching user %s", username)
search_attrs = []
if self._admin_field is not None:
search_attrs.append(self._admin_field)
if self._user_dn_format is not None:
dn = self._user_dn_format.format(username=username)
LOG.debug("LDAP searching user %r with dn %r", username, dn)
try:
results = self._server.search_s(
dn, ldap.SCOPE_BASE, attrlist=search_attrs
)
except ldap.NO_SUCH_OBJECT as e:
LOG.debug("NO_SUCH_OBJECT %s", e)
return
else:
search_filter = self._user_search_filter.format(username=username)
LOG.debug("LDAP searching user %r with filter %r", username, search_filter)
try:
results = self._server.search_s(
self._base_dn, ldap.SCOPE_SUBTREE, search_filter, search_attrs
)
except ldap.NO_SUCH_OBJECT as e:
LOG.debug("NO_SUCH_OBJECT %s", e)
return
except ldap.NO_RESULTS_RETURNED as e:
LOG.debug("NO_RESULTS_RETURNED %s", e)
return
if not results:
LOG.debug("LDAP user %r not found", username)
return None
if len(results) > 1:
err_msg = "More than one user found for %r: %r" % (
username,
[r[0] for r in results],
)
if self._ignore_multiple_results:
LOG.warning(err_msg)
else:
raise ValueError(err_msg)
dn, attributes = results[0]
LOG.debug("dn: %r, attributes %r", dn, attributes)
is_admin = False
if self._admin_field is not None:
if self._admin_field in attributes:
is_admin = bool(
self._admin_value.intersection(
[
self._decode_attribute(x)
for x in attributes[self._admin_field]
]
)
)
if not is_admin and self._admin_group_dn:
user_dn = self._user_dn_format.format(username=username)
search_filter = "(%s=%s)" % (self.admin_member_type, user_dn)
LOG.debug(
"Searching admin group %s for %s", self._admin_group_dn, search_filter
)
try:
results = self._server.search_s(
self._admin_group_dn, ldap.SCOPE_BASE, search_filter
)
except ldap.NO_SUCH_OBJECT as e:
LOG.debug("NO_SUCH_OBJECT %s", e)
else:
is_admin = bool(results)
return User(username, dn, is_admin)
def _decode_attribute(self, attribute):
if attribute and hasattr(attribute, "decode"):
decoded = attribute.decode("utf-8")
return decoded
else:
return attribute
def get_user(self, username):
"""Get the User object or None"""
return self._cache.get(username)
@reconnect
def verify_user(self, username, password):
"""
Attempts to bind as the user, then rebinds as service user again
"""
LOG.debug("LDAP verifying user %s", username)
# Empty password may successfully complete an anonymous bind.
# Explicitly disallow empty passwords.
if password == "":
return False
user = self._cache.get(username)
if user is None:
return False
try:
LOG.debug("LDAP binding user %r", user.dn)
self._server.simple_bind_s(user.dn, password)
except ldap.INVALID_CREDENTIALS:
return False
else:
return True
finally:
self._bind_to_service()
class LDAPAccessBackend(IAccessBackend):
"""
This backend allows you to authenticate against a remote LDAP server.
"""
def __init__(self, request=None, conn=None, fallback_factory=None, **kwargs):
super(LDAPAccessBackend, self).__init__(request, **kwargs)
self.conn = conn
self._fallback = None
self._fallback_factory = fallback_factory
@property
def fallback(self):
if self._fallback is None and self._fallback_factory is not None:
self._fallback = self._fallback_factory(self.request)
return self._fallback
@classmethod
def configure(cls, settings):
kwargs = super(LDAPAccessBackend, cls).configure(settings)
conn = LDAP(
admin_field=settings.get("auth.ldap.admin_field"),
admin_group_dn=settings.get("auth.ldap.admin_group_dn"),
admin_value=aslist(
settings.get("auth.ldap.admin_value", []), flatten=False
),
base_dn=settings.get("auth.ldap.base_dn"),
cache_time=settings.get("auth.ldap.cache_time"),
service_dn=settings.get("auth.ldap.service_dn"),
service_password=settings.get("auth.ldap.service_password", ""),
service_username=settings.get("auth.ldap.service_username"),
url=settings["auth.ldap.url"],
user_dn_format=settings.get("auth.ldap.user_dn_format"),
user_search_filter=settings.get("auth.ldap.user_search_filter"),
ignore_cert=asbool(settings.get("auth.ldap.ignore_cert")),
ignore_referrals=asbool(settings.get("auth.ldap.ignore_referrals", False)),
ignore_multiple_results=asbool(
settings.get("auth.ldap.ignore_multiple_results", False)
),
)
conn.connect()
kwargs["conn"] = conn
fallback = settings.get("auth.ldap.fallback")
if fallback == "config":
kw = ConfigAccessBackend.configure(settings)
kwargs["fallback_factory"] = lambda r: ConfigAccessBackend(r, **kw)
return kwargs
def _get_password_hash(self, *_): # pragma: no cover
raise RuntimeError("LDAP should never call _get_password_hash")
def verify_user(self, username, password):
return self.conn.verify_user(username, password)
def groups(self, username=None):
if self.fallback is not None:
return self.fallback.groups(username)
# LDAP doesn't support groups by default
return []
def group_members(self, group):
if self.fallback is not None:
return self.fallback.group_members(group)
# LDAP doesn't support groups by default
return []
def is_admin(self, username):
if not username:
return False
user = self.conn.get_user(username)
return user is not None and user.is_admin
def group_permissions(self, package):
if self.fallback is not None:
return self.fallback.group_permissions(package)
return {}
def user_permissions(self, package):
if self.fallback is not None:
return self.fallback.user_permissions(package)
return {}
def user_package_permissions(self, username):
if self.fallback is not None:
return self.fallback.user_package_permissions(username)
return []
def group_package_permissions(self, group):
if self.fallback is not None:
return self.fallback.group_package_permissions(group)
return []
def user_data(self, username=None):
if username is None:
if self.fallback is not None:
return self.fallback.user_data()
return []
else:
return {
"username": username,
"admin": self.is_admin(username),
"groups": self.groups(username),
}
def check_health(self):
try:
self.conn.test_connection()
except ldap.LDAPError as e:
return (False, str(e))
else:
return (True, "")