# pam.py - functions authentication, authorisation and session handling
#
# Copyright (C) 2010, 2011, 2012, 2013 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
import logging
import random
import socket
import time
from ldap.controls.ppolicy import PasswordPolicyControl, PasswordPolicyError
from ldap.filter import escape_filter_chars
import ldap
import cfg
import common
import constants
import passwd
import search
import shadow
random = random.SystemRandom()
def authenticate(binddn, password):
# open a new connection
conn = search.Connection()
# bind using the specified credentials
pwctrl = PasswordPolicyControl()
res, data, msgid, ctrls = conn.simple_bind_s(binddn, password, serverctrls=[pwctrl])
# go over bind result server controls
for ctrl in ctrls:
if ctrl.controlType == PasswordPolicyControl.controlType:
# found a password policy control
logging.debug('PasswordPolicyControl found: error=%s (%s), timeBeforeExpiration=%s, graceAuthNsRemaining=%s',
'None' if ctrl.error is None else PasswordPolicyError(ctrl.error).prettyPrint(),
ctrl.error, ctrl.timeBeforeExpiration, ctrl.graceAuthNsRemaining)
if ctrl.error == 0: # passwordExpired
return conn, constants.NSLCD_PAM_AUTHTOK_EXPIRED, PasswordPolicyError(ctrl.error).prettyPrint()
elif ctrl.error == 1: # accountLocked
return conn, constants.NSLCD_PAM_ACCT_EXPIRED, PasswordPolicyError(ctrl.error).prettyPrint()
elif ctrl.error == 2: # changeAfterReset
return conn, constants.NSLCD_PAM_NEW_AUTHTOK_REQD, 'Password change is needed after reset'
elif ctrl.error:
return conn, constants.NSLCD_PAM_PERM_DENIED, PasswordPolicyError(ctrl.error).prettyPrint()
elif ctrl.timeBeforeExpiration is not None:
return conn, constants.NSLCD_PAM_NEW_AUTHTOK_REQD, 'Password will expire in %d seconds' % ctrl.timeBeforeExpiration
elif ctrl.graceAuthNsRemaining is not None:
return conn, constants.NSLCD_PAM_NEW_AUTHTOK_REQD, 'Password expired, %d grace logins left' % ctrl.graceAuthNsRemaining
# perform search for own object (just to do any kind of search)
results = search.LDAPSearch(conn, base=binddn, scope=ldap.SCOPE_BASE,
filter='(objectClass=*)', attributes=['dn', ])
for entry in results:
if entry[0] == binddn:
return conn, constants.NSLCD_PAM_SUCCESS, ''
# if our DN wasn't found raise an error to signal bind failure
raise ldap.NO_SUCH_OBJECT()
def pwmod(conn, userdn, oldpassword, newpassword):
# perform request without old password
try:
conn.passwd_s(userdn, None, newpassword)
except ldap.LDAPError:
# retry with old password
if oldpassword:
conn.passwd_s(userdn, oldpassword, newpassword)
else:
raise
def update_lastchange(conns, userdn):
"""Try to update the shadowLastChange attribute of the entry."""
attribute = shadow.attmap['shadowLastChange']
if attribute == '${shadowLastChange:--1}':
attribute = 'shadowLastChange'
if not attribute or '$' in attribute:
raise ValueError('shadowLastChange has unsupported mapping')
# build the value for the new attribute
if attribute.lower() == 'pwdlastset':
# for AD we use another timestamp */
value = '%d000000000' % (time.time() / 100L + (134774L * 864L))
else:
# time in days since Jan 1, 1970
value = '%d' % (time.time() / (60 * 60 * 24))
# perform the modification, return at first success
for conn in conns:
try:
conn.modify_s(userdn, [(ldap.MOD_REPLACE, attribute, [value])])
return
except ldap.LDAPError:
pass # ignore error and try next connection
class PAMRequest(common.Request):
def validate(self, parameters):
"""This method checks the provided username for validity and fills
in the DN if needed."""
# check username for validity
common.validate_name(parameters['username'])
# look up user DN
entry = passwd.uid2entry(self.conn, parameters['username'])
if not entry:
# FIXME: we should close the stream with an empty response here
raise ValueError('%r: user not found' % parameters['username'])
# save the DN
parameters['userdn'] = entry[0]
# get the "real" username
value = passwd.attmap.get_rdn_value(entry[0], 'uid')
if not value:
# get the username from the uid attribute
values = entry[1]['uid']
if not values or not values[0]:
logging.warning('%s: is missing a %s attribute', entry[0], passwd.attmap['uid'])
value = values[0]
# check the username
if value and not common.is_valid_name(value):
raise ValueError('%s: has invalid %s attribute', entry[0], passwd.attmap['uid'])
# check if the username is different and update it if needed
if value != parameters['username']:
logging.info('username changed from %r to %r', parameters['username'], value)
parameters['username'] = value
class PAMAuthenticationRequest(PAMRequest):
action = constants.NSLCD_ACTION_PAM_AUTHC
def read_parameters(self, fp):
return dict(username=fp.read_string(),
service=fp.read_string(),
ruser=fp.read_string(),
rhost=fp.read_string(),
tty=fp.read_string(),
password=fp.read_string())
# TODO: log call with parameters
def write(self, username, authc=constants.NSLCD_PAM_SUCCESS,
authz=constants.NSLCD_PAM_SUCCESS, msg=''):
self.fp.write_int32(constants.NSLCD_RESULT_BEGIN)
self.fp.write_int32(authc)
self.fp.write_string(username)
self.fp.write_int32(authz)
self.fp.write_string(msg)
self.fp.write_int32(constants.NSLCD_RESULT_END)
def handle_request(self, parameters):
# if the username is blank and rootpwmoddn is configured, try to
# authenticate as administrator, otherwise validate request as usual
if not parameters['username'] and cfg.rootpwmoddn:
# authenticate as rootpwmoddn
binddn = cfg.rootpwmoddn
# if the caller is root we will allow the use of rootpwmodpw
if not parameters['password'] and self.calleruid == 0 and cfg.rootpwmodpw:
password = cfg.rootpwmodpw
elif parameters['password']:
password = parameters['password']
else:
raise ValueError('password missing')
else:
self.validate(parameters)
binddn = parameters['userdn']
password = parameters['password']
# try authentication
try:
conn, authz, msg = authenticate(binddn, password)
except ldap.INVALID_CREDENTIALS, e:
try:
msg = e[0]['desc']
except:
msg = str(e)
logging.debug('bind failed: %s', msg)
self.write(parameters['username'], authc=constants.NSLCD_PAM_AUTH_ERR, msg=msg)
return
if authz != constants.NSLCD_PAM_SUCCESS:
logging.warning('%s: %s: %s', binddn, parameters['username'], msg)
else:
logging.debug('bind successful')
# FIXME: perform shadow attribute checks with check_shadow()
self.write(parameters['username'], authz=authz, msg=msg)
class PAMAuthorisationRequest(PAMRequest):
action = constants.NSLCD_ACTION_PAM_AUTHZ
def read_parameters(self, fp):
return dict(username=fp.read_string(),
service=fp.read_string(),
ruser=fp.read_string(),
rhost=fp.read_string(),
tty=fp.read_string())
# TODO: log call with parameters
def write(self, authz=constants.NSLCD_PAM_SUCCESS, msg=''):
self.fp.write_int32(constants.NSLCD_RESULT_BEGIN)
self.fp.write_int32(authz)
self.fp.write_string(msg)
self.fp.write_int32(constants.NSLCD_RESULT_END)
def check_authz_search(self, parameters):
if not cfg.pam_authz_searches:
return
# escape all parameters
variables = dict((k, escape_filter_chars(v)) for k, v in parameters.items())
variables.update(
hostname=escape_filter_chars(socket.gethostname()),
fqdn=escape_filter_chars(socket.getfqdn()),
dn=variables['userdn'],
uid=variables['username'],
)
# go over all authz searches
for x in cfg.pam_authz_searches:
filter = x.value(variables)
logging.debug('trying pam_authz_search "%s"', filter)
srch = search.LDAPSearch(self.conn, filter=filter, attributes=('dn', ))
try:
dn, values = srch.items().next()
except StopIteration:
logging.error('pam_authz_search "%s" found no matches', filter)
raise
logging.debug('pam_authz_search found "%s"', dn)
def handle_request(self, parameters):
# fill in any missing userdn, etc.
self.validate(parameters)
# check authorisation search
try:
self.check_authz_search(parameters)
except StopIteration:
self.write(constants.NSLCD_PAM_PERM_DENIED,
'LDAP authorisation check failed')
return
# all tests passed, return OK response
self.write()
class PAMPasswordModificationRequest(PAMRequest):
action = constants.NSLCD_ACTION_PAM_PWMOD
def read_parameters(self, fp):
return dict(username=fp.read_string(),
service=fp.read_string(),
ruser=fp.read_string(),
rhost=fp.read_string(),
tty=fp.read_string(),
asroot=fp.read_int32(),
oldpassword=fp.read_string(),
newpassword=fp.read_string())
# TODO: log call with parameters
def write(self, rc=constants.NSLCD_PAM_SUCCESS, msg=''):
self.fp.write_int32(constants.NSLCD_RESULT_BEGIN)
self.fp.write_int32(rc)
self.fp.write_string(msg)
self.fp.write_int32(constants.NSLCD_RESULT_END)
def handle_request(self, parameters):
# fill in any missing userdn, etc.
self.validate(parameters)
# check if pam_password_prohibit_message is set
if cfg.pam_password_prohibit_message:
self.write(constants.NSLCD_PAM_PERM_DENIED,
cfg.pam_password_prohibit_message)
return
# check if the the user passed the rootpwmoddn
if parameters['asroot']:
binddn = cfg.rootpwmoddn
# check if rootpwmodpw should be used
if not parameters['oldpassword'] and self.calleruid == 0 and cfg.rootpwmodpw:
password = cfg.rootpwmodpw
elif parameters['oldpassword']:
password = parameters['oldpassword']
else:
raise ValueError('password missing')
else:
binddn = parameters['userdn']
password = parameters['oldpassword']
# TODO: check if shadow properties allow password change
# perform password modification
try:
conn, authz, msg = authenticate(binddn, password)
pwmod(conn, parameters['userdn'], parameters['oldpassword'], parameters['newpassword'])
# try to update lastchange with normal or user connection
update_lastchange((self.conn, conn), parameters['userdn'])
except ldap.INVALID_CREDENTIALS, e:
try:
msg = e[0]['desc']
except:
msg = str(e)
logging.debug('pwmod failed: %s', msg)
self.write(constants.NSLCD_PAM_PERM_DENIED, msg)
return
logging.debug('pwmod successful')
self.write()
SESSION_ID_LENGTH = 25
SESSION_ID_ALPHABET = (
"ABCDEFGHIJKLMNOPQRSTUVWXYZ" +
"abcdefghijklmnopqrstuvwxyz" +
"01234567890"
)
def generate_session_id():
return ''.join(
random.choice(SESSION_ID_ALPHABET)
for i in range(SESSION_ID_LENGTH)
)
class PAMSessionOpenRequest(PAMRequest):
action = constants.NSLCD_ACTION_PAM_SESS_O
def read_parameters(self, fp):
return dict(username=fp.read_string(),
service=fp.read_string(),
ruser=fp.read_string(),
rhost=fp.read_string(),
tty=fp.read_string())
# TODO: log call with parameters
def write(self, sessionid):
self.fp.write_int32(constants.NSLCD_RESULT_BEGIN)
self.fp.write_string(sessionid)
self.fp.write_int32(constants.NSLCD_RESULT_END)
def handle_request(self, parameters):
# generate a session id
session_id = generate_session_id()
self.write(session_id)
class PAMSessionCloseRequest(PAMRequest):
action = constants.NSLCD_ACTION_PAM_SESS_C
def read_parameters(self, fp):
return dict(username=fp.read_string(),
service=fp.read_string(),
ruser=fp.read_string(),
rhost=fp.read_string(),
tty=fp.read_string(),
session_id=fp.read_string())
# TODO: log call with parameters
def write(self):
self.fp.write_int32(constants.NSLCD_RESULT_BEGIN)
self.fp.write_int32(constants.NSLCD_RESULT_END)
def handle_request(self, parameters):
self.write()