Reject LDAP authentication requests with blank password. Per RFC4513 these should be treated as anonymous binds. See the Security Considerations (Section 6.3.1) for more details on this issue.

rhodecode/lib/auth_ldap.py

@@ -1,151 +1,154 b''
 # -*- coding: utf-8 -*-
 """
     rhodecode.controllers.changelog
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
     RhodeCode authentication library for LDAP
 
     :created_on: Created on Nov 17, 2010
     :author: marcink
     :copyright: (C) 2009-2011 Marcin Kuzminski <[e-mail]>
     :license: GPLv3, see COPYING for more details.
 """
 # This program 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 program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import logging
 
 from rhodecode.lib.exceptions import LdapConnectionError, LdapUsernameError, \
     LdapPasswordError
 
 log = logging.getLogger(__name__)
 
 
 try:
     import ldap
 except ImportError:
     # means that python-ldap is not installed
     pass
 
 
 class AuthLdap(object):
 
     def __init__(self, server, base_dn, port=389, bind_dn='', bind_pass='',
                  tls_kind='PLAIN', tls_reqcert='DEMAND', ldap_version=3,
                  ldap_filter='(&(objectClass=user)(!(objectClass=computer)))',
                  search_scope='SUBTREE',
                  attr_login='uid'):
         self.ldap_version = ldap_version
         ldap_server_type = 'ldap'
 
         self.TLS_KIND = tls_kind
 
         if self.TLS_KIND == 'LDAPS':
             port = port or 689
             ldap_server_type = ldap_server_type + 's'
         
         OPT_X_TLS_DEMAND = 2
         self.TLS_REQCERT = getattr(ldap, 'OPT_X_TLS_%s' % tls_reqcert, 
                                    OPT_X_TLS_DEMAND)
         self.LDAP_SERVER_ADDRESS = server
         self.LDAP_SERVER_PORT = port
 
         #USE FOR READ ONLY BIND TO LDAP SERVER
         self.LDAP_BIND_DN = bind_dn
         self.LDAP_BIND_PASS = bind_pass
 
         self.LDAP_SERVER = "%s://%s:%s" % (ldap_server_type,
                                            self.LDAP_SERVER_ADDRESS,
                                            self.LDAP_SERVER_PORT)
 
         self.BASE_DN = base_dn
         self.LDAP_FILTER = ldap_filter
         self.SEARCH_SCOPE = getattr(ldap, 'SCOPE_%s' % search_scope)
         self.attr_login = attr_login
 
     def authenticate_ldap(self, username, password):
         """Authenticate a user via LDAP and return his/her LDAP properties.
 
         Raises AuthenticationError if the credentials are rejected, or
         EnvironmentError if the LDAP server can't be reached.
 
         :param username: username
         :param password: password
         """
 
         from rhodecode.lib.helpers import chop_at
 
         uid = chop_at(username, "@%s" % self.LDAP_SERVER_ADDRESS)
 
+        if not password:
+            log.debug("Attempt to authenticate LDAP user with blank password rejected.")
+            raise LdapPasswordError()
         if "," in username:
             raise LdapUsernameError("invalid character in username: ,")
         try:
             if hasattr(ldap,'OPT_X_TLS_CACERTDIR'):
                 ldap.set_option(ldap.OPT_X_TLS_CACERTDIR, 
                                 '/etc/openldap/cacerts')
             ldap.set_option(ldap.OPT_REFERRALS, ldap.OPT_OFF)
             ldap.set_option(ldap.OPT_RESTART, ldap.OPT_ON)
             ldap.set_option(ldap.OPT_TIMEOUT, 20)
             ldap.set_option(ldap.OPT_NETWORK_TIMEOUT, 10)
             ldap.set_option(ldap.OPT_TIMELIMIT, 15)
             if self.TLS_KIND != 'PLAIN':
                 ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, self.TLS_REQCERT)
             server = ldap.initialize(self.LDAP_SERVER)
             if self.ldap_version == 2:
                 server.protocol = ldap.VERSION2
             else:
                 server.protocol = ldap.VERSION3
 
             if self.TLS_KIND == 'START_TLS':
                 server.start_tls_s()
 
             if self.LDAP_BIND_DN and self.LDAP_BIND_PASS:
                 server.simple_bind_s(self.LDAP_BIND_DN, self.LDAP_BIND_PASS)
 
             filt = '(&%s(%s=%s))' % (self.LDAP_FILTER, self.attr_login,
                                      username)
             log.debug("Authenticating %r filt %s at %s", self.BASE_DN,
                       filt, self.LDAP_SERVER)
             lobjects = server.search_ext_s(self.BASE_DN, self.SEARCH_SCOPE,
                                            filt)
 
             if not lobjects:
                 raise ldap.NO_SUCH_OBJECT()
 
             for (dn, _attrs) in lobjects:
                 if dn is None:
                     continue
 
                 try:
                     server.simple_bind_s(dn, password)
                     attrs = server.search_ext_s(dn, ldap.SCOPE_BASE,
                                                 '(objectClass=*)')[0][1]
                     break
 
                 except ldap.INVALID_CREDENTIALS, e:
                     log.debug("LDAP rejected password for user '%s' (%s): %s",
                               uid, username, dn)
 
             else:
                 log.debug("No matching LDAP objects for authentication "
                           "of '%s' (%s)", uid, username)
                 raise LdapPasswordError()
 
         except ldap.NO_SUCH_OBJECT, e:
             log.debug("LDAP says no such user '%s' (%s)", uid, username)
             raise LdapUsernameError()
         except ldap.SERVER_DOWN, e:
             raise LdapConnectionError("LDAP can't access "
                                       "authentication server")
 
         return (dn, attrs)