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# Reads important GPO parameters and updates Samba
# Copyright (C) Luke Morrison <luc785@.hotmail.com> 2013
#
# 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 sys
import os
import errno
import tdb
sys.path.insert(0, "bin/python")
from samba import NTSTATUSError
from ConfigParser import ConfigParser
from StringIO import StringIO
from abc import ABCMeta, abstractmethod
import xml.etree.ElementTree as etree
import re
from samba.net import Net
from samba.dcerpc import nbt
from samba import smb
import samba.gpo as gpo
from samba.param import LoadParm
from uuid import UUID
from tempfile import NamedTemporaryFile
try:
from enum import Enum
GPOSTATE = Enum('GPOSTATE', 'APPLY ENFORCE UNAPPLY')
except ImportError:
class GPOSTATE:
APPLY = 1
ENFORCE = 2
UNAPPLY = 3
class gp_log:
''' Log settings overwritten by gpo apply
The gp_log is an xml file that stores a history of gpo changes (and the
original setting value).
The log is organized like so:
<gp>
<user name="KDC-1$">
<applylog>
<guid count="0" value="{31B2F340-016D-11D2-945F-00C04FB984F9}" />
</applylog>
<guid value="{31B2F340-016D-11D2-945F-00C04FB984F9}">
<gp_ext name="System Access">
<attribute name="minPwdAge">-864000000000</attribute>
<attribute name="maxPwdAge">-36288000000000</attribute>
<attribute name="minPwdLength">7</attribute>
<attribute name="pwdProperties">1</attribute>
</gp_ext>
<gp_ext name="Kerberos Policy">
<attribute name="ticket_lifetime">1d</attribute>
<attribute name="renew_lifetime" />
<attribute name="clockskew">300</attribute>
</gp_ext>
</guid>
</user>
</gp>
Each guid value contains a list of extensions, which contain a list of
attributes. The guid value represents a GPO. The attributes are the values
of those settings prior to the application of the GPO.
The list of guids is enclosed within a user name, which represents the user
the settings were applied to. This user may be the samaccountname of the
local computer, which implies that these are machine policies.
The applylog keeps track of the order in which the GPOs were applied, so
that they can be rolled back in reverse, returning the machine to the state
prior to policy application.
'''
def __init__(self, user, gpostore, db_log=None):
''' Initialize the gp_log
param user - the username (or machine name) that policies are
being applied to
param gpostore - the GPOStorage obj which references the tdb which
contains gp_logs
param db_log - (optional) a string to initialize the gp_log
'''
self._state = GPOSTATE.APPLY
self.gpostore = gpostore
self.username = user
if db_log:
self.gpdb = etree.fromstring(db_log)
else:
self.gpdb = etree.Element('gp')
self.user = user
user_obj = self.gpdb.find('user[@name="%s"]' % user)
if user_obj is None:
user_obj = etree.SubElement(self.gpdb, 'user')
user_obj.attrib['name'] = user
def state(self, value):
''' Policy application state
param value - APPLY, ENFORCE, or UNAPPLY
The behavior of the gp_log depends on whether we are applying policy,
enforcing policy, or unapplying policy. During an apply, old settings
are recorded in the log. During an enforce, settings are being applied
but the gp_log does not change. During an unapply, additions to the log
should be ignored (since function calls to apply settings are actually
reverting policy), but removals from the log are allowed.
'''
# If we're enforcing, but we've unapplied, apply instead
if value == GPOSTATE.ENFORCE:
user_obj = self.gpdb.find('user[@name="%s"]' % self.user)
apply_log = user_obj.find('applylog')
if apply_log is None or len(apply_log) == 0:
self._state = GPOSTATE.APPLY
else:
self._state = value
else:
self._state = value
def set_guid(self, guid):
''' Log to a different GPO guid
param guid - guid value of the GPO from which we're applying
policy
'''
self.guid = guid
user_obj = self.gpdb.find('user[@name="%s"]' % self.user)
obj = user_obj.find('guid[@value="%s"]' % guid)
if obj is None:
obj = etree.SubElement(user_obj, 'guid')
obj.attrib['value'] = guid
if self._state == GPOSTATE.APPLY:
apply_log = user_obj.find('applylog')
if apply_log is None:
apply_log = etree.SubElement(user_obj, 'applylog')
prev = apply_log.find('guid[@value="%s"]' % guid)
if prev is None:
item = etree.SubElement(apply_log, 'guid')
item.attrib['count'] = '%d' % (len(apply_log)-1)
item.attrib['value'] = guid
def apply_log_pop(self):
''' Pop a GPO guid from the applylog
return - last applied GPO guid
Removes the GPO guid last added to the list, which is the most recently
applied GPO.
'''
user_obj = self.gpdb.find('user[@name="%s"]' % self.user)
apply_log = user_obj.find('applylog')
if apply_log is not None:
ret = apply_log.find('guid[@count="%d"]' % (len(apply_log)-1))
if ret is not None:
apply_log.remove(ret)
return ret.attrib['value']
if len(apply_log) == 0 and apply_log in user_obj:
user_obj.remove(apply_log)
return None
def store(self, gp_ext_name, attribute, old_val):
''' Store an attribute in the gp_log
param gp_ext_name - Name of the extension applying policy
param attribute - The attribute being modified
param old_val - The value of the attribute prior to policy
application
'''
if self._state == GPOSTATE.UNAPPLY or self._state == GPOSTATE.ENFORCE:
return None
user_obj = self.gpdb.find('user[@name="%s"]' % self.user)
guid_obj = user_obj.find('guid[@value="%s"]' % self.guid)
assert guid_obj is not None, "gpo guid was not set"
ext = guid_obj.find('gp_ext[@name="%s"]' % gp_ext_name)
if ext is None:
ext = etree.SubElement(guid_obj, 'gp_ext')
ext.attrib['name'] = gp_ext_name
attr = ext.find('attribute[@name="%s"]' % attribute)
if attr is None:
attr = etree.SubElement(ext, 'attribute')
attr.attrib['name'] = attribute
attr.text = old_val
def retrieve(self, gp_ext_name, attribute):
''' Retrieve a stored attribute from the gp_log
param gp_ext_name - Name of the extension which applied policy
param attribute - The attribute being retrieved
return - The value of the attribute prior to policy
application
'''
user_obj = self.gpdb.find('user[@name="%s"]' % self.user)
guid_obj = user_obj.find('guid[@value="%s"]' % self.guid)
assert guid_obj is not None, "gpo guid was not set"
ext = guid_obj.find('gp_ext[@name="%s"]' % gp_ext_name)
if ext is not None:
attr = ext.find('attribute[@name="%s"]' % attribute)
if attr is not None:
return attr.text
return None
def list(self, gp_extensions):
''' Return a list of attributes, their previous values, and functions
to set them
param gp_extensions - list of extension objects, for retrieving attr to
func mappings
return - list of (attr, value, apply_func) tuples for
unapplying policy
'''
user_obj = self.gpdb.find('user[@name="%s"]' % self.user)
guid_obj = user_obj.find('guid[@value="%s"]' % self.guid)
assert guid_obj is not None, "gpo guid was not set"
ret = []
data_maps = {}
for gp_ext in gp_extensions:
data_maps.update(gp_ext.apply_map())
exts = guid_obj.findall('gp_ext')
if exts is not None:
for ext in exts:
attrs = ext.findall('attribute')
for attr in attrs:
func = None
if attr.attrib['name'] in data_maps[ext.attrib['name']]:
func = data_maps[ext.attrib['name']]\
[attr.attrib['name']][-1]
else:
for dmap in data_maps[ext.attrib['name']].keys():
if data_maps[ext.attrib['name']][dmap][0] == \
attr.attrib['name']:
func = data_maps[ext.attrib['name']][dmap][-1]
break
ret.append((attr.attrib['name'], attr.text, func))
return ret
def delete(self, gp_ext_name, attribute):
''' Remove an attribute from the gp_log
param gp_ext_name - name of extension from which to remove the
attribute
param attribute - attribute to remove
'''
user_obj = self.gpdb.find('user[@name="%s"]' % self.user)
guid_obj = user_obj.find('guid[@value="%s"]' % self.guid)
assert guid_obj is not None, "gpo guid was not set"
ext = guid_obj.find('gp_ext[@name="%s"]' % gp_ext_name)
if ext is not None:
attr = ext.find('attribute[@name="%s"]' % attribute)
if attr is not None:
ext.remove(attr)
if len(ext) == 0:
guid_obj.remove(ext)
def commit(self):
''' Write gp_log changes to disk '''
self.gpostore.store(self.username, etree.tostring(self.gpdb, 'utf-8'))
class GPOStorage:
def __init__(self, log_file):
if os.path.isfile(log_file):
self.log = tdb.open(log_file)
else:
self.log = tdb.Tdb(log_file, 0, tdb.DEFAULT, os.O_CREAT|os.O_RDWR)
def start(self):
self.log.transaction_start()
def get_int(self, key):
try:
return int(self.log.get(key))
except TypeError:
return None
def get(self, key):
return self.log.get(key)
def get_gplog(self, user):
return gp_log(user, self, self.log.get(user))
def store(self, key, val):
self.log.store(key, val)
def cancel(self):
self.log.transaction_cancel()
def delete(self, key):
self.log.delete(key)
def commit(self):
self.log.transaction_commit()
def __del__(self):
self.log.close()
class gp_ext(object):
__metaclass__ = ABCMeta
def __init__(self, logger):
self.logger = logger
@abstractmethod
def list(self, rootpath):
pass
@abstractmethod
def apply_map(self):
pass
@abstractmethod
def read(self, policy):
pass
def parse(self, afile, ldb, gp_db, lp):
self.ldb = ldb
self.gp_db = gp_db
self.lp = lp
local_path = self.lp.cache_path('gpo_cache')
data_file = os.path.join(local_path, check_safe_path(afile).upper())
if os.path.exists(data_file):
return self.read(open(data_file, 'r').read())
return None
@abstractmethod
def __str__(self):
pass
class gp_ext_setter():
__metaclass__ = ABCMeta
def __init__(self, logger, ldb, gp_db, lp, attribute, val):
self.logger = logger
self.ldb = ldb
self.attribute = attribute
self.val = val
self.lp = lp
self.gp_db = gp_db
def explicit(self):
return self.val
def update_samba(self):
(upd_sam, value) = self.mapper().get(self.attribute)
upd_sam(value())
@abstractmethod
def mapper(self):
pass
@abstractmethod
def __str__(self):
pass
class gp_inf_ext(gp_ext):
@abstractmethod
def list(self, rootpath):
pass
@abstractmethod
def apply_map(self):
pass
def read(self, policy):
ret = False
inftable = self.apply_map()
current_section = None
# So here we would declare a boolean,
# that would get changed to TRUE.
#
# If at any point in time a GPO was applied,
# then we return that boolean at the end.
inf_conf = ConfigParser()
inf_conf.optionxform=str
try:
inf_conf.readfp(StringIO(policy))
except:
inf_conf.readfp(StringIO(policy.decode('utf-16')))
for section in inf_conf.sections():
current_section = inftable.get(section)
if not current_section:
continue
for key, value in inf_conf.items(section):
if current_section.get(key):
(att, setter) = current_section.get(key)
value = value.encode('ascii', 'ignore')
ret = True
setter(self.logger, self.ldb, self.gp_db, self.lp, att,
value).update_samba()
self.gp_db.commit()
return ret
@abstractmethod
def __str__(self):
pass
''' Fetch the hostname of a writable DC '''
def get_dc_hostname(creds, lp):
net = Net(creds=creds, lp=lp)
cldap_ret = net.finddc(domain=lp.get('realm'), flags=(nbt.NBT_SERVER_LDAP |
nbt.NBT_SERVER_DS))
return cldap_ret.pdc_dns_name
''' Fetch a list of GUIDs for applicable GPOs '''
def get_gpo_list(dc_hostname, creds, lp):
gpos = []
ads = gpo.ADS_STRUCT(dc_hostname, lp, creds)
if ads.connect():
gpos = ads.get_gpo_list(creds.get_username())
return gpos
def cache_gpo_dir(conn, cache, sub_dir):
loc_sub_dir = sub_dir.upper()
local_dir = os.path.join(cache, loc_sub_dir)
try:
os.makedirs(local_dir, mode=0o755)
except OSError as e:
if e.errno != errno.EEXIST:
raise
for fdata in conn.list(sub_dir):
if fdata['attrib'] & smb.FILE_ATTRIBUTE_DIRECTORY:
cache_gpo_dir(conn, cache, os.path.join(sub_dir, fdata['name']))
else:
local_name = fdata['name'].upper()
f = NamedTemporaryFile(delete=False, dir=local_dir)
fname = os.path.join(sub_dir, fdata['name']).replace('/', '\\')
f.write(conn.loadfile(fname))
f.close()
os.rename(f.name, os.path.join(local_dir, local_name))
def check_safe_path(path):
dirs = re.split('/|\\\\', path)
if 'sysvol' in path:
dirs = dirs[dirs.index('sysvol')+1:]
if not '..' in dirs:
return os.path.join(*dirs)
raise OSError(path)
def check_refresh_gpo_list(dc_hostname, lp, creds, gpos):
conn = smb.SMB(dc_hostname, 'sysvol', lp=lp, creds=creds, sign=True)
cache_path = lp.cache_path('gpo_cache')
for gpo in gpos:
if not gpo.file_sys_path:
continue
cache_gpo_dir(conn, cache_path, check_safe_path(gpo.file_sys_path))
def gpo_version(lp, path):
# gpo.gpo_get_sysvol_gpt_version() reads the GPT.INI from a local file,
# read from the gpo client cache.
gpt_path = lp.cache_path(os.path.join('gpo_cache', path))
return int(gpo.gpo_get_sysvol_gpt_version(gpt_path)[1])
def apply_gp(lp, creds, test_ldb, logger, store, gp_extensions):
gp_db = store.get_gplog(creds.get_username())
dc_hostname = get_dc_hostname(creds, lp)
gpos = get_gpo_list(dc_hostname, creds, lp)
try:
check_refresh_gpo_list(dc_hostname, lp, creds, gpos)
except:
logger.error('Failed downloading gpt cache from \'%s\' using SMB' \
% dc_hostname)
return
for gpo_obj in gpos:
guid = gpo_obj.name
if guid == 'Local Policy':
continue
path = os.path.join(lp.get('realm'), 'Policies', guid).upper()
version = gpo_version(lp, path)
if version != store.get_int(guid):
logger.info('GPO %s has changed' % guid)
gp_db.state(GPOSTATE.APPLY)
else:
gp_db.state(GPOSTATE.ENFORCE)
gp_db.set_guid(guid)
store.start()
for ext in gp_extensions:
try:
ext.parse(ext.list(path), test_ldb, gp_db, lp)
except Exception as e:
logger.error('Failed to parse gpo %s for extension %s' % \
(guid, str(ext)))
logger.error('Message was: ' + str(e))
store.cancel()
continue
store.store(guid, '%i' % version)
store.commit()
def unapply_log(gp_db):
while True:
item = gp_db.apply_log_pop()
if item:
yield item
else:
break
def unapply_gp(lp, creds, test_ldb, logger, store, gp_extensions):
gp_db = store.get_gplog(creds.get_username())
gp_db.state(GPOSTATE.UNAPPLY)
for gpo_guid in unapply_log(gp_db):
gp_db.set_guid(gpo_guid)
unapply_attributes = gp_db.list(gp_extensions)
for attr in unapply_attributes:
attr_obj = attr[-1](logger, test_ldb, gp_db, lp, attr[0], attr[1])
attr_obj.mapper()[attr[0]][0](attr[1]) # Set the old value
gp_db.delete(str(attr_obj), attr[0])
gp_db.commit()
def parse_gpext_conf(smb_conf):
lp = LoadParm()
if smb_conf is not None:
lp.load(smb_conf)
else:
lp.load_default()
ext_conf = lp.state_path('gpext.conf')
parser = ConfigParser()
parser.read(ext_conf)
return lp, parser
def atomic_write_conf(lp, parser):
ext_conf = lp.state_path('gpext.conf')
with NamedTemporaryFile(delete=False, dir=os.path.dirname(ext_conf)) as f:
parser.write(f)
os.rename(f.name, ext_conf)
def check_guid(guid):
# Check for valid guid with curly braces
if guid[0] != '{' or guid[-1] != '}' or len(guid) != 38:
return False
try:
UUID(guid, version=4)
except ValueError:
return False
return True
def register_gp_extension(guid, name, path,
smb_conf=None, machine=True, user=True):
# Check that the module exists
if not os.path.exists(path):
return False
if not check_guid(guid):
return False
lp, parser = parse_gpext_conf(smb_conf)
if not guid in parser.sections():
parser.add_section(guid)
parser.set(guid, 'DllName', path)
parser.set(guid, 'ProcessGroupPolicy', name)
parser.set(guid, 'NoMachinePolicy', 0 if machine else 1)
parser.set(guid, 'NoUserPolicy', 0 if user else 1)
atomic_write_conf(lp, parser)
return True
def list_gp_extensions(smb_conf=None):
_, parser = parse_gpext_conf(smb_conf)
results = {}
for guid in parser.sections():
results[guid] = {}
results[guid]['DllName'] = parser.get(guid, 'DllName')
results[guid]['ProcessGroupPolicy'] = \
parser.get(guid, 'ProcessGroupPolicy')
results[guid]['MachinePolicy'] = \
not int(parser.get(guid, 'NoMachinePolicy'))
results[guid]['UserPolicy'] = not int(parser.get(guid, 'NoUserPolicy'))
return results
def unregister_gp_extension(guid, smb_conf=None):
if not check_guid(guid):
return False
lp, parser = parse_gpext_conf(smb_conf)
if guid in parser.sections():
parser.remove_section(guid)
atomic_write_conf(lp, parser)
return True
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