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freeipa/ipaserver/rpcserver.py
John Dennis bba4ccb3a0 add session manager and cache krb auth 
This patch adds a session manager and support for caching
authentication in the session. Major elements of the patch are:

* Add a session manager to support cookie based sessions which
  stores session data in a memcached entry.

* Add ipalib/krb_utils.py which contains functions to parse ccache
  names, format principals, format KRB timestamps, and a KRB_CCache
  class which reads ccache entry and allows one to extract information
  such as the principal, credentials, credential timestamps, etc.

* Move krb constants defined in ipalib/rpc.py to ipa_krb_utils.py so
  that all kerberos items are co-located.

* Modify javascript in ipa.js so that the IPA.command() RPC call
  checks for authentication needed error response and if it receives
  it sends a GET request to /ipa/login URL to refresh credentials.

* Add session_auth_duration config item to constants.py, used to
  configure how long a session remains valid.

* Add parse_time_duration utility to ipalib/util.py. Used to parse the
  session_auth_duration config item.

* Update the default.conf.5 man page to document session_auth_duration
  config item (also added documentation for log_manager config items
  which had been inadvertantly omitted from a previous commit).

* Add SessionError object to ipalib/errors.py

* Move Kerberos protection in Apache config from /ipa to /ipa/xml and
  /ipa/login

* Add SessionCCache class to session.py to manage temporary Kerberos
  ccache file in effect for the duration of an RPC command.

* Adds a krblogin plugin used to implement the /ipa/login
  handler. login handler sets the session expiration time, currently
  60 minutes or the expiration of the TGT, whichever is shorter. It
  also copies the ccache provied by mod_auth_kerb into the session
  data.  The json handler will later extract and validate the ccache
  belonging to the session.

* Refactored the WSGI handlers so that json and xlmrpc could have
  independent behavior, this also moves where create and destroy
  context occurs, now done in the individual handler rather than the
  parent class.

* The json handler now looks up the session data, validates the ccache
  bound to the session, if it's expired replies with authenicated
  needed error.

* Add documentation to session.py. Fully documents the entire process,
  got questions, read the doc.

* Add exclusions to make-lint as needed.
2012-02-09 13:20:45 -06:00

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# Authors:
# Jason Gerard DeRose <jderose@redhat.com>
#
# Copyright (C) 2008 Red Hat
# see file 'COPYING' for use and warranty information
#
# 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/>.
"""
RPC server.
Also see the `ipalib.rpc` module.
"""
from cgi import parse_qs
from xml.sax.saxutils import escape
from xmlrpclib import Fault
from ipalib.backend import Executioner
from ipalib.errors import PublicError, InternalError, CommandError, JSONError, ConversionError, CCacheError, RefererError
from ipalib.request import context, Connection, destroy_context
from ipalib.rpc import xml_dumps, xml_loads
from ipalib.util import make_repr, parse_time_duration
from ipalib.compat import json
from ipalib.session import session_mgr, read_krbccache_file, store_krbccache_file, delete_krbccache_file, fmt_time, default_max_session_lifetime
from ipalib.backend import Backend
from ipalib.krb_utils import krb5_parse_ccache, KRB5_CCache, krb5_format_tgt_principal_name, krb5_format_service_principal_name, krb_ticket_expiration_threshold
from wsgiref.util import shift_path_info
from ipapython.version import VERSION
import base64
import os
import string
import datetime
from decimal import Decimal
_not_found_template = """<html>
<head>
<title>404 Not Found</title>
</head>
<body>
<h1>Not Found</h1>
<p>
The requested URL <strong>%(url)s</strong> was not found on this server.
</p>
</body>
</html>"""
def not_found(environ, start_response):
"""
Return a 404 Not Found error.
"""
status = '404 Not Found'
response_headers = [('Content-Type', 'text/html')]
start_response(status, response_headers)
output = _not_found_template % dict(
url=escape(environ['SCRIPT_NAME'] + environ['PATH_INFO'])
)
return [output]
def read_input(environ):
"""
Read the request body from environ['wsgi.input'].
"""
try:
length = int(environ.get('CONTENT_LENGTH'))
except (ValueError, TypeError):
return
return environ['wsgi.input'].read(length)
def params_2_args_options(params):
if len(params) == 0:
return (tuple(), dict())
if len(params) == 1:
return (params[0], dict())
return (params[0], params[1])
def nicify_query(query, encoding='utf-8'):
if not query:
return
for (key, value) in query.iteritems():
if len(value) == 0:
yield (key, None)
elif len(value) == 1:
yield (key, value[0].decode(encoding))
else:
yield (key, tuple(v.decode(encoding) for v in value))
def extract_query(environ):
"""
Return the query as a ``dict``, or ``None`` if no query is presest.
"""
qstr = None
if environ['REQUEST_METHOD'] == 'POST':
if environ['CONTENT_TYPE'] == 'application/x-www-form-urlencoded':
qstr = read_input(environ)
elif environ['REQUEST_METHOD'] == 'GET':
qstr = environ['QUERY_STRING']
if qstr:
query = dict(nicify_query(
parse_qs(qstr)#, keep_blank_values=True)
))
else:
query = {}
environ['wsgi.query'] = query
return query
class session(Executioner):
"""
WSGI routing middleware and entry point into IPA server.
The `session` plugin is the entry point into the IPA server. It will create
an LDAP connection (from a session cookie or the KRB5CCNAME header) and then
dispatch the request to the appropriate application. In WSGI parlance,
`session` is *middleware*.
"""
def __init__(self):
super(session, self).__init__()
self.__apps = {}
def __iter__(self):
for key in sorted(self.__apps):
yield key
def __getitem__(self, key):
return self.__apps[key]
def __contains__(self, key):
return key in self.__apps
def __call__(self, environ, start_response):
self.debug('WSGI session.__call__:')
try:
return self.route(environ, start_response)
finally:
destroy_context()
def _on_finalize(self):
self.url = self.env['mount_ipa']
super(session, self)._on_finalize()
def route(self, environ, start_response):
key = shift_path_info(environ)
if key in self.__apps:
app = self.__apps[key]
return app(environ, start_response)
return not_found(environ, start_response)
def mount(self, app, key):
"""
Mount the WSGI application *app* at *key*.
"""
# if self.__islocked__():
# raise StandardError('%s.mount(): locked, cannot mount %r at %r' % (
# self.name, app, key)
# )
if key in self.__apps:
raise StandardError('%s.mount(): cannot replace %r with %r at %r' % (
self.name, self.__apps[key], app, key)
)
self.debug('Mounting %r at %r', app, key)
self.__apps[key] = app
class WSGIExecutioner(Executioner):
"""
Base class for execution backends with a WSGI application interface.
"""
content_type = None
key = ''
def set_api(self, api):
super(WSGIExecutioner, self).set_api(api)
if 'session' in self.api.Backend:
self.api.Backend.session.mount(self, self.key)
def _on_finalize(self):
self.url = self.env.mount_ipa + self.key
super(WSGIExecutioner, self)._on_finalize()
def wsgi_execute(self, environ):
result = None
error = None
_id = None
lang = os.environ['LANG']
name = None
args = ()
options = {}
if not 'HTTP_REFERER' in environ:
return self.marshal(result, RefererError(referer='missing'), _id)
if not environ['HTTP_REFERER'].startswith('https://%s/ipa' % self.api.env.host) and not self.env.in_tree:
return self.marshal(result, RefererError(referer=environ['HTTP_REFERER']), _id)
try:
if ('HTTP_ACCEPT_LANGUAGE' in environ):
lang_reg_w_q = environ['HTTP_ACCEPT_LANGUAGE'].split(',')[0]
lang_reg = lang_reg_w_q.split(';')[0]
lang_ = lang_reg.split('-')[0]
if '-' in lang_reg:
reg = lang_reg.split('-')[1].upper();
else:
reg = lang_.upper()
os.environ['LANG'] = '%s_%s' % (lang_, reg)
if (
environ.get('CONTENT_TYPE', '').startswith(self.content_type)
and environ['REQUEST_METHOD'] == 'POST'
):
data = read_input(environ)
(name, args, options, _id) = self.unmarshal(data)
else:
(name, args, options, _id) = self.simple_unmarshal(environ)
if name not in self.Command:
raise CommandError(name=name)
result = self.Command[name](*args, **options)
except PublicError, e:
error = e
except StandardError, e:
self.exception(
'non-public: %s: %s', e.__class__.__name__, str(e)
)
error = InternalError()
finally:
os.environ['LANG'] = lang
if name:
try:
params = self.Command[name].args_options_2_params(*args, **options)
except Exception, e:
self.info(
'exception %s caught when converting options: %s', e.__class__.__name__, str(e)
)
# get at least some context of what is going on
params = options
if error:
self.info('%s: %s(%s): %s', context.principal, name, ', '.join(self.Command[name]._repr_iter(**params)), e.__class__.__name__)
else:
self.info('%s: %s(%s): SUCCESS', context.principal, name, ', '.join(self.Command[name]._repr_iter(**params)))
else:
self.info('%s: %s', context.principal, e.__class__.__name__)
return self.marshal(result, error, _id)
def simple_unmarshal(self, environ):
name = environ['PATH_INFO'].strip('/')
options = extract_query(environ)
return (name, tuple(), options, None)
def __call__(self, environ, start_response):
"""
WSGI application for execution.
"""
self.debug('WSGI WSGIExecutioner.__call__:')
try:
status = '200 OK'
response = self.wsgi_execute(environ)
headers = [('Content-Type', self.content_type + '; charset=utf-8')]
except StandardError, e:
self.exception('WSGI %s.__call__():', self.name)
status = '500 Internal Server Error'
response = status
headers = [('Content-Type', 'text/plain')]
session_data = getattr(context, 'session_data', None)
if session_data is not None:
# Send session cookie back and store session data
# FIXME: the URL path should be retreived from somewhere (but where?), not hardcoded
session_cookie = session_mgr.generate_cookie('/ipa', session_data['session_id'])
headers.append(('Set-Cookie', session_cookie))
start_response(status, headers)
return [response]
def unmarshal(self, data):
raise NotImplementedError('%s.unmarshal()' % self.fullname)
def marshal(self, result, error, _id=None):
raise NotImplementedError('%s.marshal()' % self.fullname)
class xmlserver(WSGIExecutioner):
"""
Execution backend plugin for XML-RPC server.
Also see the `ipalib.rpc.xmlclient` plugin.
"""
content_type = 'text/xml'
key = 'xml'
def _on_finalize(self):
self.__system = {
'system.listMethods': self.listMethods,
'system.methodSignature': self.methodSignature,
'system.methodHelp': self.methodHelp,
}
super(xmlserver, self)._on_finalize()
def __call__(self, environ, start_response):
'''
'''
self.debug('WSGI xmlserver.__call__:')
self.create_context(ccache=environ.get('KRB5CCNAME'))
try:
response = super(xmlserver, self).__call__(environ, start_response)
finally:
destroy_context()
return response
def listMethods(self, *params):
return tuple(name.decode('UTF-8') for name in self.Command)
def methodSignature(self, *params):
return u'methodSignature not implemented'
def methodHelp(self, *params):
return u'methodHelp not implemented'
def marshaled_dispatch(self, data, ccache, client_ip):
"""
Execute the XML-RPC request contained in ``data``.
"""
try:
self.create_context(ccache=ccache, client_ip=client_ip)
(params, name) = xml_loads(data)
if name in self.__system:
response = (self.__system[name](*params),)
else:
(args, options) = params_2_args_options(params)
response = (self.execute(name, *args, **options),)
except PublicError, e:
self.debug('response: %s: %s', e.__class__.__name__, str(e))
response = Fault(e.errno, e.strerror)
return xml_dumps(response, methodresponse=True)
def unmarshal(self, data):
(params, name) = xml_loads(data)
(args, options) = params_2_args_options(params)
return (name, args, options, None)
def marshal(self, result, error, _id=None):
if error:
self.debug('response: %s: %s', error.__class__.__name__, str(error))
response = Fault(error.errno, error.strerror)
else:
if isinstance(result, dict):
self.debug('response: entries returned %d', result.get('count', 1))
response = (result,)
return xml_dumps(response, methodresponse=True)
def json_encode_binary(val):
'''
JSON cannot encode binary values. We encode binary values in Python str
objects and text in Python unicode objects. In order to allow a binary
object to be passed through JSON we base64 encode it thus converting it to
text which JSON can transport. To assure we recognize the value is a base64
encoded representation of the original binary value and not confuse it with
other text we convert the binary value to a dict in this form:
{'__base64__' : base64_encoding_of_binary_value}
This modification of the original input value cannot be done "in place" as
one might first assume (e.g. replacing any binary items in a container
(e.g. list, tuple, dict) with the base64 dict because the container might be
an immutable object (i.e. a tuple). Therefore this function returns a copy
of any container objects it encounters with tuples replaced by lists. This
is O.K. because the JSON encoding will map both lists and tuples to JSON
arrays.
'''
if isinstance(val, dict):
new_dict = {}
for k,v in val.items():
if isinstance(v, str):
new_dict[k] = {'__base64__' : base64.b64encode(v)}
else:
new_dict[k] = json_encode_binary(v)
del val
return new_dict
elif isinstance(val, (list, tuple)):
new_list = []
n = len(val)
i = 0
while i < n:
v = val[i]
if isinstance(v, str):
new_list.append({'__base64__' : base64.b64encode(v)})
else:
new_list.append(json_encode_binary(v))
i += 1
del val
return new_list
elif isinstance(val, str):
return {'__base64__' : base64.b64encode(val)}
elif isinstance(val, Decimal):
return {'__base64__' : base64.b64encode(str(val))}
else:
return val
def json_decode_binary(val):
'''
JSON cannot transport binary data. In order to transport binary data we
convert binary data to a form like this:
{'__base64__' : base64_encoding_of_binary_value}
see json_encode_binary()
After JSON had decoded the JSON stream back into a Python object we must
recursively scan the object looking for any dicts which might represent
binary values and replace the dict containing the base64 encoding of the
binary value with the decoded binary value. Unlike the encoding problem
where the input might consist of immutable object, all JSON decoded
container are mutable so the conversion could be done in place. However we
don't modify objects in place because of side effects which may be
dangerous. Thus we elect to spend a few more cycles and avoid the
possibility of unintended side effects in favor of robustness.
'''
if isinstance(val, dict):
if val.has_key('__base64__'):
return base64.b64decode(val['__base64__'])
else:
new_dict = {}
for k,v in val.items():
if isinstance(v, dict) and v.has_key('__base64__'):
new_dict[k] = base64.b64decode(v['__base64__'])
else:
new_dict[k] = json_decode_binary(v)
del val
return new_dict
elif isinstance(val, list):
new_list = []
n = len(val)
i = 0
while i < n:
v = val[i]
if isinstance(v, dict) and v.has_key('__base64__'):
binary_val = base64.b64decode(v['__base64__'])
new_list.append(binary_val)
else:
new_list.append(json_decode_binary(v))
i += 1
del val
return new_list
else:
if isinstance(val, basestring):
try:
return val.decode('utf-8')
except UnicodeDecodeError:
raise ConversionError(
name=val,
error='incorrect type'
)
else:
return val
class jsonserver(WSGIExecutioner):
"""
JSON RPC server.
For information on the JSON-RPC spec, see:
http://json-rpc.org/wiki/specification
"""
content_type = 'application/json'
key = 'json'
def need_login(self, start_response):
status = '401 Unauthorized'
headers = []
response = ''
self.debug('jsonserver: %s', status)
start_response(status, headers)
return [response]
def __call__(self, environ, start_response):
'''
'''
self.debug('WSGI jsonserver.__call__:')
# Load the session data
session_data = session_mgr.load_session_data(environ.get('HTTP_COOKIE'))
session_id = session_data['session_id']
self.debug('jsonserver.__call__: session_id=%s start_timestamp=%s write_timestamp=%s expiration_timestamp=%s',
session_id,
fmt_time(session_data['session_start_timestamp']),
fmt_time(session_data['session_write_timestamp']),
fmt_time(session_data['session_expiration_timestamp']))
ccache_data = session_data.get('ccache_data')
# Redirect to login if no Kerberos credentials
if ccache_data is None:
self.debug('no ccache, need login')
return self.need_login(start_response)
krbccache_pathname = store_krbccache_file(ccache_data)
# Redirect to login if Kerberos credentials are expired
cc = KRB5_CCache(krbccache_pathname)
ldap_principal = krb5_format_service_principal_name('ldap', self.api.env.host, self.api.env.realm)
tgt_principal = krb5_format_tgt_principal_name(self.api.env.realm)
if not (cc.credential_is_valid(ldap_principal) or cc.credential_is_valid(tgt_principal)):
self.debug('ccache expired, deleting session, need login')
session_mgr.delete_session_data(session_id)
delete_krbccache_file(krbccache_pathname)
return self.need_login(start_response)
# Store the session data in the per-thread context
setattr(context, 'session_data', session_data)
self.create_context(ccache=krbccache_pathname)
try:
response = super(jsonserver, self).__call__(environ, start_response)
finally:
# Kerberos may have updated the ccache data, refresh our copy of it
session_data['ccache_data'] = read_krbccache_file(krbccache_pathname)
# Delete the temporary ccache file we used
delete_krbccache_file(krbccache_pathname)
# Store the session data.
session_mgr.store_session_data(session_data)
destroy_context()
return response
def marshal(self, result, error, _id=None):
if error:
assert isinstance(error, PublicError)
error = dict(
code=error.errno,
message=error.strerror,
name=error.__class__.__name__,
)
response = dict(
result=result,
error=error,
id=_id,
principal=unicode(context.principal),
version=unicode(VERSION),
)
response = json_encode_binary(response)
return json.dumps(response, sort_keys=True, indent=4)
def unmarshal(self, data):
try:
d = json.loads(data)
except ValueError, e:
raise JSONError(error=e)
if not isinstance(d, dict):
raise JSONError(error='Request must be a dict')
if 'method' not in d:
raise JSONError(error='Request is missing "method"')
if 'params' not in d:
raise JSONError(error='Request is missing "params"')
d = json_decode_binary(d)
method = d['method']
params = d['params']
_id = d.get('id')
if not isinstance(params, (list, tuple)):
raise JSONError(error='params must be a list')
if len(params) != 2:
raise JSONError(
error='params must contain [args, options]'
)
args = params[0]
if not isinstance(args, (list, tuple)):
raise JSONError(
error='params[0] (aka args) must be a list'
)
options = params[1]
if not isinstance(options, dict):
raise JSONError(
error='params[1] (aka options) must be a dict'
)
options = dict((str(k), v) for (k, v) in options.iteritems())
return (method, args, options, _id)
class krblogin(Backend):
key = 'login'
def __init__(self):
super(krblogin, self).__init__()
def _on_finalize(self):
super(krblogin, self)._on_finalize()
self.api.Backend.session.mount(self, self.key)
# Set the session expiration time
try:
seconds = parse_time_duration(self.api.env.session_auth_duration)
self.session_auth_duration = int(seconds)
self.debug("session_auth_duration: %s", datetime.timedelta(seconds=self.session_auth_duration))
except Exception, e:
self.session_auth_duration = default_max_session_lifetime
self.error('unable to parse session_auth_duration, defaulting to %d: %s',
self.session_auth_duration, e)
def __call__(self, environ, start_response):
headers = []
self.debug('WSGI krblogin.__call__:')
# Get the ccache created by mod_auth_kerb
ccache=environ.get('KRB5CCNAME')
if ccache is None:
status = '500 Internal Error'
response = 'KRB5CCNAME not defined'
start_response(status, headers)
return [response]
ccache_scheme, ccache_location = krb5_parse_ccache(ccache)
assert ccache_scheme == 'FILE'
# Retrieve the session data (or newly create)
session_data = session_mgr.load_session_data(environ.get('HTTP_COOKIE'))
session_id = session_data['session_id']
# Copy the ccache file contents into the session data
session_data['ccache_data'] = read_krbccache_file(ccache_location)
# Compute when the session will expire
cc = KRB5_CCache(ccache)
tgt_principal = krb5_format_tgt_principal_name(self.api.env.realm)
authtime, starttime, endtime, renew_till = cc.get_credential_times(tgt_principal)
# Account for clock skew and/or give us some time leeway
krb_expiration = endtime - krb_ticket_expiration_threshold
# Set the session expiration time
session_mgr.set_session_expiration_time(session_data,
lifetime=self.session_auth_duration,
max_age=krb_expiration)
# Store the session data now that it's been updated with the ccache
session_mgr.store_session_data(session_data)
self.debug('krblogin: ccache="%s" session_id="%s" ccache="%s"',
ccache, session_id, ccache)
# Return success and set session cookie
status = '200 Success'
response = ''
session_cookie = session_mgr.generate_cookie('/ipa', session_data['session_id'])
headers.append(('Set-Cookie', session_cookie))
start_response(status, headers)
return [response]
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