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# pam.py - functions authentication, authorisation and session handling
#
# Copyright (C) 2010, 2011, 2012 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 socket
from ldap.filter import escape_filter_chars as escape
import ldap
import cfg
import common
import constants
import passwd
def try_bind(userdn, password):
# open a new connection
conn = ldap.initialize(cfg.uri)
# bind using the specified credentials
conn.simple_bind_s(userdn, password)
# perform search for own object (just to do any kind of search)
res = conn.search_s(userdn, ldap.SCOPE_BASE, '(objectClass=*)', ['dn', ])
for entry in res:
if entry[0] == userdn:
return
raise ldap.NO_SUCH_OBJECT()
class PAMRequest(common.Request):
def validate_request(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:
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', dn, passwd.attmap['uid'])
value = values[0]
# check the username
if value and not common.isvalidname(value):
raise ValueError('%s: has invalid %s attribute', dn, 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(),
ignore_userdn=fp.read_string(),
service=fp.read_string(),
password=fp.read_string())
#self.validate_request()
# TODO: log call with parameters
def write(self, parameters, code=constants.NSLCD_PAM_SUCCESS, msg=''):
self.fp.write_int32(constants.NSLCD_RESULT_BEGIN)
self.fp.write_string(parameters['username'])
self.fp.write_string('') # userdn
self.fp.write_int32(code) # authc
self.fp.write_int32(constants.NSLCD_PAM_SUCCESS) # authz
self.fp.write_string(msg) # authzmsg
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
userdn = 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_request(parameters)
userdn = parameters['userdn']
password = parameters['password']
# try authentication
try:
try_bind(userdn, password)
logging.debug('bind successful')
self.write(parameters)
except ldap.INVALID_CREDENTIALS, e:
try:
msg = e[0]['desc']
except:
msg = str(e)
logging.debug('bind failed: %s', msg)
self.write(parameters, constants.NSLCD_PAM_AUTH_ERR, msg)
class PAMAuthorisationRequest(PAMRequest):
action = constants.NSLCD_ACTION_PAM_AUTHZ
def read_parameters(self, fp):
return dict(username=fp.read_string(),
ignore_userdn=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, parameters, code=constants.NSLCD_PAM_SUCCESS, msg=''):
self.fp.write_int32(constants.NSLCD_RESULT_BEGIN)
self.fp.write_string(parameters['username'])
self.fp.write_string('') # userdn
self.fp.write_int32(code)
self.fp.write_string(msg)
self.fp.write_int32(constants.NSLCD_RESULT_END)
def check_authzsearch(self, parameters):
if not cfg.pam_authz_searches:
return
# escape all parameters
variables = dict((k, escape(v)) for k, v in parameters.items())
variables.update(
hostname=escape(socket.gethostname()),
fqdn=escape(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)
search = common.Search(self.conn, filter=filter, attributes=('dn', ))
try:
dn, values = search.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_request(parameters)
# check authorisation search
try:
self.check_authzsearch(parameters)
except StopIteration:
self.write(parameters, constants.NSLCD_PAM_PERM_DENIED,
'LDAP authorisation check failed')
return
# all tests passed, return OK response
self.write(parameters)
#NSLCD_ACTION_PAM_SESS_O
#NSLCD_ACTION_PAM_SESS_C
#NSLCD_ACTION_PAM_PWMOD
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