openstack/keystone
Code Issues Proposed changes

sync oslo policy

Browse Source 
Related-Bug: 1221889
Change-Id: I0fd0be982879647ef73081326708ec37b1cb9fd9
This commit is contained in:
guang-yee 2013-09-24 14:47:31 -05:00
parent 328d1673db
commit af68f75978
4 changed files with 304 additions and 205 deletions
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2
keystone/common/config.py
View File

@ -37,8 +37,6 @@ FILE_OPTIONS = {
default='http://localhost:%(admin_port)s/'),
cfg.StrOpt('onready'),
cfg.StrOpt('auth_admin_prefix', default=''),
cfg.StrOpt('policy_file', default='policy.json'),
cfg.StrOpt('policy_default_rule', default=None),
# default max request size is 112k
cfg.IntOpt('max_request_body_size', default=114688),
cfg.IntOpt('max_param_size', default=64),

470
keystone/openstack/common/policy.py
View File

@ -1,6 +1,6 @@
# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright (c) 2012 OpenStack Foundation
# Copyright (c) 2012 OpenStack Foundation.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
@ -57,33 +57,48 @@ as it allows particular rules to be explicitly disabled.
"""
import abc
import logging
import re
import urllib
import urllib2
from keystone.openstack.common.gettextutils import _
from keystone.openstack.common import jsonutils
from oslo.config import cfg
import six
from keystone.openstack.common import fileutils
from keystone.openstack.common.gettextutils import _ # noqa
from keystone.openstack.common import jsonutils
from keystone.openstack.common import log as logging
policy_opts = [
cfg.StrOpt('policy_file',
default='policy.json',
help=_('JSON file containing policy')),
cfg.StrOpt('policy_default_rule',
default='default',
help=_('Rule enforced when requested rule is not found')),
]
CONF = cfg.CONF
CONF.register_opts(policy_opts)
LOG = logging.getLogger(__name__)
_rules = None
_checks = {}
class PolicyNotAuthorized(Exception):
def __init__(self, rule):
msg = _("Policy doesn't allow %s to be performed.") % rule
super(PolicyNotAuthorized, self).__init__(msg)
class Rules(dict):
"""
A store for rules. Handles the default_rule setting directly.
"""
"""A store for rules. Handles the default_rule setting directly."""
@classmethod
def load_json(cls, data, default_rule=None):
"""
Allow loading of JSON rule data.
"""
"""Allow loading of JSON rule data."""
# Suck in the JSON data and parse the rules
rules = dict((k, parse_rule(v)) for k, v in
@ -100,12 +115,18 @@ class Rules(dict):
def __missing__(self, key):
"""Implements the default rule handling."""
if isinstance(self.default_rule, dict):
raise KeyError(key)
# If the default rule isn't actually defined, do something
# reasonably intelligent
if not self.default_rule or self.default_rule not in self:
raise KeyError(key)
return self[self.default_rule]
if isinstance(self.default_rule, BaseCheck):
return self.default_rule
elif isinstance(self.default_rule, six.string_types):
return self[self.default_rule]
def __str__(self):
"""Dumps a string representation of the rules."""
@ -123,87 +144,157 @@ class Rules(dict):
return jsonutils.dumps(out_rules, indent=4)
# Really have to figure out a way to deprecate this
def set_rules(rules):
"""Set the rules in use for policy checks."""
class Enforcer(object):
"""Responsible for loading and enforcing rules.
global _rules
_rules = rules
# Ditto
def reset():
"""Clear the rules used for policy checks."""
global _rules
_rules = None
def check(rule, target, creds, exc=None, *args, **kwargs):
"""
Checks authorization of a rule against the target and credentials.
:param rule: The rule to evaluate.
:param target: As much information about the object being operated
on as possible, as a dictionary.
:param creds: As much information about the user performing the
action as possible, as a dictionary.
:param exc: Class of the exception to raise if the check fails.
Any remaining arguments passed to check() (both
positional and keyword arguments) will be passed to
the exception class. If exc is not provided, returns
False.
:return: Returns False if the policy does not allow the action and
exc is not provided; otherwise, returns a value that
evaluates to True. Note: for rules using the "case"
expression, this True value will be the specified string
from the expression.
:param policy_file: Custom policy file to use, if none is
specified, `CONF.policy_file` will be
used.
:param rules: Default dictionary / Rules to use. It will be
considered just in the first instantiation. If
`load_rules(True)`, `clear()` or `set_rules(True)`
is called this will be overwritten.
:param default_rule: Default rule to use, CONF.default_rule will
be used if none is specified.
"""
# Allow the rule to be a Check tree
if isinstance(rule, BaseCheck):
result = rule(target, creds)
elif not _rules:
# No rules to reference means we're going to fail closed
result = False
else:
try:
# Evaluate the rule
result = _rules[rule](target, creds)
except KeyError:
# If the rule doesn't exist, fail closed
def __init__(self, policy_file=None, rules=None, default_rule=None):
self.rules = Rules(rules, default_rule)
self.default_rule = default_rule or CONF.policy_default_rule
self.policy_path = None
self.policy_file = policy_file or CONF.policy_file
def set_rules(self, rules, overwrite=True):
"""Create a new Rules object based on the provided dict of rules.
:param rules: New rules to use. It should be an instance of dict.
:param overwrite: Whether to overwrite current rules or update them
with the new rules.
"""
if not isinstance(rules, dict):
raise TypeError(_("Rules must be an instance of dict or Rules, "
"got %s instead") % type(rules))
if overwrite:
self.rules = Rules(rules, self.default_rule)
else:
self.rules.update(rules)
def clear(self):
"""Clears Enforcer rules, policy's cache and policy's path."""
self.set_rules({})
self.default_rule = None
self.policy_path = None
def load_rules(self, force_reload=False):
"""Loads policy_path's rules.
Policy file is cached and will be reloaded if modified.
:param force_reload: Whether to overwrite current rules.
"""
if not self.policy_path:
self.policy_path = self._get_policy_path()
reloaded, data = fileutils.read_cached_file(self.policy_path,
force_reload=force_reload)
if reloaded or not self.rules:
rules = Rules.load_json(data, self.default_rule)
self.set_rules(rules)
LOG.debug(_("Rules successfully reloaded"))
def _get_policy_path(self):
"""Locate the policy json data file.
:param policy_file: Custom policy file to locate.
:returns: The policy path
:raises: ConfigFilesNotFoundError if the file couldn't
be located.
"""
policy_file = CONF.find_file(self.policy_file)
if policy_file:
return policy_file
raise cfg.ConfigFilesNotFoundError((CONF.policy_file,))
def enforce(self, rule, target, creds, do_raise=False,
exc=None, *args, **kwargs):
"""Checks authorization of a rule against the target and credentials.
:param rule: A string or BaseCheck instance specifying the rule
to evaluate.
:param target: As much information about the object being operated
on as possible, as a dictionary.
:param creds: As much information about the user performing the
action as possible, as a dictionary.
:param do_raise: Whether to raise an exception or not if check
fails.
:param exc: Class of the exception to raise if the check fails.
Any remaining arguments passed to check() (both
positional and keyword arguments) will be passed to
the exception class. If not specified, PolicyNotAuthorized
will be used.
:return: Returns False if the policy does not allow the action and
exc is not provided; otherwise, returns a value that
evaluates to True. Note: for rules using the "case"
expression, this True value will be the specified string
from the expression.
"""
# NOTE(flaper87): Not logging target or creds to avoid
# potential security issues.
LOG.debug(_("Rule %s will be now enforced") % rule)
self.load_rules()
# Allow the rule to be a Check tree
if isinstance(rule, BaseCheck):
result = rule(target, creds, self)
elif not self.rules:
# No rules to reference means we're going to fail closed
result = False
else:
try:
# Evaluate the rule
result = self.rules[rule](target, creds, self)
except KeyError:
LOG.debug(_("Rule [%s] doesn't exist") % rule)
# If the rule doesn't exist, fail closed
result = False
# If it is False, raise the exception if requested
if exc and result is False:
raise exc(*args, **kwargs)
# If it is False, raise the exception if requested
if do_raise and not result:
if exc:
raise exc(*args, **kwargs)
return result
raise PolicyNotAuthorized(rule)
return result
class BaseCheck(object):
"""
Abstract base class for Check classes.
"""
"""Abstract base class for Check classes."""
__metaclass__ = abc.ABCMeta
@abc.abstractmethod
def __str__(self):
"""
Retrieve a string representation of the Check tree rooted at
this node.
"""
"""String representation of the Check tree rooted at this node."""
pass
@abc.abstractmethod
def __call__(self, target, cred):
"""
Perform the check. Returns False to reject the access or a
def __call__(self, target, cred, enforcer):
"""Triggers if instance of the class is called.
Performs the check. Returns False to reject the access or a
true value (not necessary True) to accept the access.
"""
@ -211,44 +302,39 @@ class BaseCheck(object):
class FalseCheck(BaseCheck):
"""
A policy check that always returns False (disallow).
"""
"""A policy check that always returns False (disallow)."""
def __str__(self):
"""Return a string representation of this check."""
return "!"
def __call__(self, target, cred):
def __call__(self, target, cred, enforcer):
"""Check the policy."""
return False
class TrueCheck(BaseCheck):
"""
A policy check that always returns True (allow).
"""
"""A policy check that always returns True (allow)."""
def __str__(self):
"""Return a string representation of this check."""
return "@"
def __call__(self, target, cred):
def __call__(self, target, cred, enforcer):
"""Check the policy."""
return True
class Check(BaseCheck):
"""
A base class to allow for user-defined policy checks.
"""
"""A base class to allow for user-defined policy checks."""
def __init__(self, kind, match):
"""
"""Initiates Check instance.
:param kind: The kind of the check, i.e., the field before the
':'.
:param match: The match of the check, i.e., the field after
@ -265,14 +351,13 @@ class Check(BaseCheck):
class NotCheck(BaseCheck):
"""
"""Implements the "not" logical operator.
A policy check that inverts the result of another policy check.
Implements the "not" operator.
"""
def __init__(self, rule):
"""
Initialize the 'not' check.
"""Initialize the 'not' check.
:param rule: The rule to negate. Must be a Check.
"""
@ -284,24 +369,23 @@ class NotCheck(BaseCheck):
return "not %s" % self.rule
def __call__(self, target, cred):
"""
Check the policy. Returns the logical inverse of the wrapped
check.
def __call__(self, target, cred, enforcer):
"""Check the policy.
Returns the logical inverse of the wrapped check.
"""
return not self.rule(target, cred)
return not self.rule(target, cred, enforcer)
class AndCheck(BaseCheck):
"""
A policy check that requires that a list of other checks all
return True. Implements the "and" operator.
"""Implements the "and" logical operator.
A policy check that requires that a list of other checks all return True.
"""
def __init__(self, rules):
"""
Initialize the 'and' check.
"""Initialize the 'and' check.
:param rules: A list of rules that will be tested.
"""
@ -313,20 +397,21 @@ class AndCheck(BaseCheck):
return "(%s)" % ' and '.join(str(r) for r in self.rules)
def __call__(self, target, cred):
"""
Check the policy. Requires that all rules accept in order to
return True.
def __call__(self, target, cred, enforcer):
"""Check the policy.
Requires that all rules accept in order to return True.
"""
for rule in self.rules:
if not rule(target, cred):
if not rule(target, cred, enforcer):
return False
return True
def add_check(self, rule):
"""
"""Adds rule to be tested.
Allows addition of another rule to the list of rules that will
be tested. Returns the AndCheck object for convenience.
"""
@ -336,14 +421,14 @@ class AndCheck(BaseCheck):
class OrCheck(BaseCheck):
"""
"""Implements the "or" operator.
A policy check that requires that at least one of a list of other
checks returns True. Implements the "or" operator.
checks returns True.
"""
def __init__(self, rules):
"""
Initialize the 'or' check.
"""Initialize the 'or' check.
:param rules: A list of rules that will be tested.
"""
@ -355,20 +440,20 @@ class OrCheck(BaseCheck):
return "(%s)" % ' or '.join(str(r) for r in self.rules)
def __call__(self, target, cred):
"""
Check the policy. Requires that at least one rule accept in
order to return True.
def __call__(self, target, cred, enforcer):
"""Check the policy.
Requires that at least one rule accept in order to return True.
"""
for rule in self.rules:
if rule(target, cred):
if rule(target, cred, enforcer):
return True
return False
def add_check(self, rule):
"""
"""Adds rule to be tested.
Allows addition of another rule to the list of rules that will
be tested. Returns the OrCheck object for convenience.
"""
@ -378,9 +463,7 @@ class OrCheck(BaseCheck):
def _parse_check(rule):
"""
Parse a single base check rule into an appropriate Check object.
"""
"""Parse a single base check rule into an appropriate Check object."""
# Handle the special checks
if rule == '!':
@ -391,7 +474,7 @@ def _parse_check(rule):
try:
kind, match = rule.split(':', 1)
except Exception:
LOG.exception(_("Failed to understand rule %(rule)s") % locals())
LOG.exception(_("Failed to understand rule %s") % rule)
# If the rule is invalid, we'll fail closed
return FalseCheck()
@ -406,9 +489,9 @@ def _parse_check(rule):
def _parse_list_rule(rule):
"""
Provided for backwards compatibility. Translates the old
list-of-lists syntax into a tree of Check objects.
"""Translates the old list-of-lists syntax into a tree of Check objects.
Provided for backwards compatibility.
"""
# Empty rule defaults to True
@ -436,7 +519,7 @@ def _parse_list_rule(rule):
or_list.append(AndCheck(and_list))
# If we have only one check, omit the "or"
if len(or_list) == 0:
if not or_list:
return FalseCheck()
elif len(or_list) == 1:
return or_list[0]
@ -449,8 +532,7 @@ _tokenize_re = re.compile(r'\s+')
def _parse_tokenize(rule):
"""
Tokenizer for the policy language.
"""Tokenizer for the policy language.
Most of the single-character tokens are specified in the
_tokenize_re; however, parentheses need to be handled specially,
@ -499,16 +581,16 @@ def _parse_tokenize(rule):
class ParseStateMeta(type):
"""
Metaclass for the ParseState class. Facilitates identifying
reduction methods.
"""Metaclass for the ParseState class.
Facilitates identifying reduction methods.
"""
def __new__(mcs, name, bases, cls_dict):
"""
Create the class. Injects the 'reducers' list, a list of
tuples matching token sequences to the names of the
corresponding reduction methods.
"""Create the class.
Injects the 'reducers' list, a list of tuples matching token sequences
to the names of the corresponding reduction methods.
"""
reducers = []
@ -525,10 +607,10 @@ class ParseStateMeta(type):
def reducer(*tokens):
"""
Decorator for reduction methods. Arguments are a sequence of
tokens, in order, which should trigger running this reduction
method.
"""Decorator for reduction methods.
Arguments are a sequence of tokens, in order, which should trigger running
this reduction method.
"""
def decorator(func):
@ -545,10 +627,10 @@ def reducer(*tokens):
class ParseState(object):
"""
Implement the core of parsing the policy language. Uses a greedy
reduction algorithm to reduce a sequence of tokens into a single
terminal, the value of which will be the root of the Check tree.
"""Implement the core of parsing the policy language.
Uses a greedy reduction algorithm to reduce a sequence of tokens into
a single terminal, the value of which will be the root of the Check tree.
Note: error reporting is rather lacking. The best we can get with
this parser formulation is an overall "parse failed" error.
@ -565,28 +647,28 @@ class ParseState(object):
self.values = []
def reduce(self):
"""
Perform a greedy reduction of the token stream. If a reducer
method matches, it will be executed, then the reduce() method
will be called recursively to search for any more possible
reductions.
"""Perform a greedy reduction of the token stream.
If a reducer method matches, it will be executed, then the
reduce() method will be called recursively to search for any more
possible reductions.
"""
for reduction, methname in self.reducers:
if (len(self.tokens) >= len(reduction) and
self.tokens[-len(reduction):] == reduction):
# Get the reduction method
meth = getattr(self, methname)
self.tokens[-len(reduction):] == reduction):
# Get the reduction method
meth = getattr(self, methname)
# Reduce the token stream
results = meth(*self.values[-len(reduction):])
# Reduce the token stream
results = meth(*self.values[-len(reduction):])
# Update the tokens and values
self.tokens[-len(reduction):] = [r[0] for r in results]
self.values[-len(reduction):] = [r[1] for r in results]
# Update the tokens and values
self.tokens[-len(reduction):] = [r[0] for r in results]
self.values[-len(reduction):] = [r[1] for r in results]
# Check for any more reductions
return self.reduce()
# Check for any more reductions
return self.reduce()
def shift(self, tok, value):
"""Adds one more token to the state. Calls reduce()."""
@ -599,9 +681,9 @@ class ParseState(object):
@property
def result(self):
"""
Obtain the final result of the parse. Raises ValueError if
the parse failed to reduce to a single result.
"""Obtain the final result of the parse.
Raises ValueError if the parse failed to reduce to a single result.
"""
if len(self.values) != 1:
@ -618,35 +700,31 @@ class ParseState(object):
@reducer('check', 'and', 'check')
def _make_and_expr(self, check1, _and, check2):
"""
Create an 'and_expr' from two checks joined by the 'and'
operator.
"""Create an 'and_expr'.
Join two checks by the 'and' operator.
"""
return [('and_expr', AndCheck([check1, check2]))]
@reducer('and_expr', 'and', 'check')
def _extend_and_expr(self, and_expr, _and, check):
"""
Extend an 'and_expr' by adding one more check.
"""
"""Extend an 'and_expr' by adding one more check."""
return [('and_expr', and_expr.add_check(check))]
@reducer('check', 'or', 'check')
def _make_or_expr(self, check1, _or, check2):
"""
Create an 'or_expr' from two checks joined by the 'or'
operator.
"""Create an 'or_expr'.
Join two checks by the 'or' operator.
"""
return [('or_expr', OrCheck([check1, check2]))]
@reducer('or_expr', 'or', 'check')
def _extend_or_expr(self, or_expr, _or, check):
"""
Extend an 'or_expr' by adding one more check.
"""
"""Extend an 'or_expr' by adding one more check."""
return [('or_expr', or_expr.add_check(check))]
@ -658,7 +736,8 @@ class ParseState(object):
def _parse_text_rule(rule):
"""
"""Parses policy to the tree.
Translates a policy written in the policy language into a tree of
Check objects.
"""
@ -676,16 +755,14 @@ def _parse_text_rule(rule):
return state.result
except ValueError:
# Couldn't parse the rule
LOG.exception(_("Failed to understand rule %(rule)r") % locals())
LOG.exception(_("Failed to understand rule %r") % rule)
# Fail closed
return FalseCheck()
def parse_rule(rule):
"""
Parses a policy rule into a tree of Check objects.
"""
"""Parses a policy rule into a tree of Check objects."""
# If the rule is a string, it's in the policy language
if isinstance(rule, basestring):
@ -694,8 +771,7 @@ def parse_rule(rule):
def register(name, func=None):
"""
Register a function or Check class as a policy check.
"""Register a function or Check class as a policy check.
:param name: Gives the name of the check type, e.g., 'rule',
'role', etc. If name is None, a default check type
@ -722,13 +798,11 @@ def register(name, func=None):
@register("rule")
class RuleCheck(Check):
def __call__(self, target, creds):
"""
Recursively checks credentials based on the defined rules.
"""
def __call__(self, target, creds, enforcer):
"""Recursively checks credentials based on the defined rules."""
try:
return _rules[self.match](target, creds)
return enforcer.rules[self.match](target, creds, enforcer)
except KeyError:
# We don't have any matching rule; fail closed
return False
@ -736,7 +810,7 @@ class RuleCheck(Check):
@register("role")
class RoleCheck(Check):
def __call__(self, target, creds):
def __call__(self, target, creds, enforcer):
"""Check that there is a matching role in the cred dict."""
return self.match.lower() in [x.lower() for x in creds['roles']]
@ -744,9 +818,8 @@ class RoleCheck(Check):
@register('http')
class HttpCheck(Check):
def __call__(self, target, creds):
"""
Check http: rules by calling to a remote server.
def __call__(self, target, creds, enforcer):
"""Check http: rules by calling to a remote server.
This example implementation simply verifies that the response
is exactly 'True'.
@ -762,9 +835,8 @@ class HttpCheck(Check):
@register(None)
class GenericCheck(Check):
def __call__(self, target, creds):
"""
Check an individual match.
def __call__(self, target, creds, enforcer):
"""Check an individual match.
Matches look like:
@ -773,7 +845,13 @@ class GenericCheck(Check):
"""
# TODO(termie): do dict inspection via dot syntax
match = self.match % target
try:
match = self.match % target
except KeyError:
# While doing GenericCheck if key not
# present in Target return false
return False
if self.kind in creds:
return match == unicode(creds[self.kind])
return match == six.text_type(creds[self.kind])
return False

15
keystone/policy/backends/rules.py
View File

@ -31,6 +31,7 @@ CONF = config.CONF
LOG = logging.getLogger(__name__)
_ENFORCER = None
_POLICY_PATH = None
_POLICY_CACHE = {}
@ -38,26 +39,31 @@ _POLICY_CACHE = {}
def reset():
global _POLICY_PATH
global _POLICY_CACHE
global _ENFORCER
_POLICY_PATH = None
_POLICY_CACHE = {}
common_policy.reset()
_ENFORCER = None
def init():
global _POLICY_PATH
global _POLICY_CACHE
global _ENFORCER
if not _POLICY_PATH:
_POLICY_PATH = CONF.policy_file
if not os.path.exists(_POLICY_PATH):
_POLICY_PATH = CONF.find_file(_POLICY_PATH)
if not _ENFORCER:
_ENFORCER = common_policy.Enforcer(policy_file=_POLICY_PATH)
utils.read_cached_file(_POLICY_PATH,
_POLICY_CACHE,
reload_func=_set_rules)
def _set_rules(data):
global _ENFORCER
default_rule = CONF.policy_default_rule
common_policy.set_rules(common_policy.Rules.load_json(
_ENFORCER.set_rules(common_policy.Rules.load_json(
data, default_rule))
@ -83,9 +89,10 @@ def enforce(credentials, action, target, do_raise=True):
# Add the exception arguments if asked to do a raise
extra = {}
if do_raise:
extra.update(exc=exception.ForbiddenAction, action=action)
extra.update(exc=exception.ForbiddenAction, action=action,
do_raise=do_raise)
return common_policy.check(action, target, credentials, **extra)
return _ENFORCER.enforce(action, target, credentials, **extra)
class Policy(policy.Driver):

22
keystone/tests/test_policy.py
View File

@ -85,7 +85,7 @@ class PolicyTestCase(tests.TestCase):
these_rules = common_policy.Rules(
dict((k, common_policy.parse_rule(v))
for k, v in self.rules.items()))
common_policy.set_rules(these_rules)
rules._ENFORCER.set_rules(these_rules)
def tearDown(self):
rules.reset()
@ -167,14 +167,24 @@ class DefaultPolicyTestCase(tests.TestCase):
self._set_rules('default')
self.credentials = {}
# FIXME(gyee): latest Oslo policy Enforcer class reloads the rules in
# its enforce() method even though rules has been initialized via
# set_rules(). To make it easier to do our tests, we're going to
# monkeypatch load_roles() so it does nothing. This seem like a bug in
# Oslo policy as we shoudn't have to reload the rules if they have
# already been set using set_rules().
self._old_load_rules = rules._ENFORCER.load_rules
setattr(rules._ENFORCER, 'load_rules', lambda *args, **kwargs: None)
def _set_rules(self, default_rule):
these_rules = common_policy.Rules(
dict((k, common_policy.parse_rule(v))
for k, v in self.rules.items()), default_rule)
common_policy.set_rules(these_rules)
rules._ENFORCER.set_rules(these_rules)
def tearDown(self):
super(DefaultPolicyTestCase, self).tearDown()
rules._ENFORCER.load_rules = self._old_load_rules
rules.reset()
def test_policy_called(self):
@ -185,6 +195,12 @@ class DefaultPolicyTestCase(tests.TestCase):
rules.enforce(self.credentials, "example:noexist", {})
def test_default_not_found(self):
self._set_rules("default_noexist")
new_default_rule = "default_noexist"
# FIXME(gyee): need to overwrite the Enforcer's default_rule first
# as it is recreating the rules with its own default_rule instead
# of the default_rule passed in from set_rules(). I think this is a
# bug in Oslo policy.
rules._ENFORCER.default_rule = new_default_rule
self._set_rules(new_default_rule)
self.assertRaises(exception.ForbiddenAction, rules.enforce,
self.credentials, "example:noexist", {})