# -*- coding: utf-8 -*- # # Copyright (c) 2012 OpenStack Foundation. # All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); you may # not use this file except in compliance with the License. You may obtain # a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the # License for the specific language governing permissions and limitations # under the License. """ Common Policy Engine Implementation Policies are expressed as a target and an associated rule:: "": The `target` is specific to the service that is conducting policy enforcement. Typically, the target refers to an API call. For the `` part, see `Policy Rule Expressions`. Policy Rule Expressions ~~~~~~~~~~~~~~~~~~~~~~~ Policy rules can be expressed in one of two forms: a string written in the new policy language or a list of lists. The string format is preferred since it's easier for most people to understand. In the policy language, each check is specified as a simple "a:b" pair that is matched to the correct class to perform that check: +--------------------------------+------------------------------------------+ | TYPE | SYNTAX | +================================+==========================================+ |User's Role | role:admin | +--------------------------------+------------------------------------------+ |Rules already defined on policy | rule:admin_required | +--------------------------------+------------------------------------------+ |Against URLs¹ | http://my-url.org/check | +--------------------------------+------------------------------------------+ |User attributes² | project_id:%(target.project.id)s | +--------------------------------+------------------------------------------+ |Strings | - :'xpto2035abc' | | | - 'myproject': | +--------------------------------+------------------------------------------+ | | - project_id:xpto2035abc | |Literals | - domain_id:20 | | | - True:%(user.enabled)s | +--------------------------------+------------------------------------------+ ¹URL checking must return ``True`` to be valid ²User attributes (obtained through the token): user_id, domain_id or project_id Conjunction operators ``and`` and ``or`` are available, allowing for more expressiveness in crafting policies. For example:: "role:admin or (project_id:%(project_id)s and role:projectadmin)" The policy language also has the ``not`` operator, allowing a richer policy rule:: "project_id:%(project_id)s and not role:dunce" Operator precedence is below: +------------+-------------+-------------+ | PRECEDENCE | TYPE | EXPRESSION | +============+=============+=============+ | 4 | Grouping | (...) | +------------+-------------+-------------+ | 3 | Logical NOT | not ... | +------------+-------------+-------------+ | 2 | Logical AND | ... and ... | +------------+-------------+-------------+ | 1 | Logical OR | ... or ... | +------------+-------------+-------------+ Operator with larger precedence number precedes others with smaller numbers. In the list-of-lists representation, each check inside the innermost list is combined as with an "and" conjunction -- for that check to pass, all the specified checks must pass. These innermost lists are then combined as with an "or" conjunction. As an example, take the following rule, expressed in the list-of-lists representation:: [["role:admin"], ["project_id:%(project_id)s", "role:projectadmin"]] Finally, two special policy checks should be mentioned; the policy check "@" will always accept an access, and the policy check "!" will always reject an access. (Note that if a rule is either the empty list (``[]``) or the empty string (``""``), this is equivalent to the "@" policy check.) Of these, the "!" policy check is probably the most useful, as it allows particular rules to be explicitly disabled. Generic Checks ~~~~~~~~~~~~~~ A `generic` check is used to perform matching against attributes that are sent along with the API calls. These attributes can be used by the policy engine (on the right side of the expression), by using the following syntax:: :%(user.id)s The value on the right-hand side is either a string or resolves to a string using regular Python string substitution. The available attributes and values are dependent on the program that is using the common policy engine. All of these attributes (related to users, API calls, and context) can be checked against each other or against constants. It is important to note that these attributes are specific to the service that is conducting policy enforcement. Generic checks can be used to perform policy checks on the following user attributes obtained through a token: - user_id - domain_id or project_id (depending on the token scope) - list of roles held for the given token scope .. note:: Some resources which are exposed by the API do not support policy enforcement by user_id, and only support policy enforcement by project_id. Some global resources do not support policy enforcement by combination of user_id and project_id. For example, a check on the user_id would be defined as:: user_id: Together with the previously shown example, a complete generic check would be:: user_id:%(user.id)s It is also possible to perform checks against other attributes that represent the credentials. This is done by adding additional values to the ``creds`` dict that is passed to the :meth:`~oslo_policy.policy.Enforcer.enforce` method. Special Checks ~~~~~~~~~~~~~~ Special checks allow for more flexibility than is possible using generic checks. The built-in special check types are ``role``, ``rule``, and ``http`` checks. Role Check ^^^^^^^^^^ A ``role`` check is used to check if a specific role is present in the supplied credentials. A role check is expressed as:: "role:" Rule Check ^^^^^^^^^^ A :class:`rule check ` is used to reference another defined rule by its name. This allows for common checks to be defined once as a reusable rule, which is then referenced within other rules. It also allows one to define a set of checks as a more descriptive name to aid in readability of policy. A rule check is expressed as:: "rule:" The following example shows a role check that is defined as a rule, which is then used via a rule check:: "admin_required": "role:admin" "": "rule:admin_required" HTTP Check ^^^^^^^^^^ An ``http`` check is used to make an HTTP request to a remote server to determine the results of the check. The target and credentials are passed to the remote server for evaluation. The action is authorized if the remote server returns a response of ``True``. An http check is expressed as:: "http:" It is expected that the target URI contains a string formatting keyword, where the keyword is a key from the target dictionary. An example of an http check where the `name` key from the target is used to construct the URL is would be defined as:: "http://server.test/%(name)s" Registering New Special Checks ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ It is also possible for additional special check types to be registered using the :func:`~oslo_policy.policy.register` function. The following classes can be used as parents for custom special check types: * :class:`~oslo_policy.policy.AndCheck` * :class:`~oslo_policy.policy.NotCheck` * :class:`~oslo_policy.policy.OrCheck` * :class:`~oslo_policy.policy.RuleCheck` Default Rule ~~~~~~~~~~~~ A default rule can be defined, which will be enforced when a rule does not exist for the target that is being checked. By default, the rule associated with the rule name of ``default`` will be used as the default rule. It is possible to use a different rule name as the default rule by setting the ``policy_default_rule`` configuration setting to the desired rule name. """ import collections import copy import logging import os import warnings from oslo_config import cfg from oslo_context import context from oslo_serialization import jsonutils from oslo_utils import strutils import six import yaml from oslo_policy import _cache_handler from oslo_policy import _checks from oslo_policy._i18n import _ from oslo_policy import _parser from oslo_policy import opts LOG = logging.getLogger(__name__) register = _checks.register """Register a function or :class:`.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 will be registered. :param func: If given, provides the function or class to register. If not given, returns a function taking one argument to specify the function or class to register, allowing use as a decorator. """ Check = _checks.Check """A base class to allow for user-defined policy checks. :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 the ``:``. """ AndCheck = _checks.AndCheck """Implements the "and" logical operator. A policy check that requires that a list of other checks all return True. :param list rules: rules that will be tested. """ NotCheck = _checks.NotCheck """Implements the "not" logical operator. A policy check that inverts the result of another policy check. :param rule: The rule to negate. """ OrCheck = _checks.OrCheck """Implements the "or" operator. A policy check that requires that at least one of a list of other checks returns ``True``. :param rules: A list of rules that will be tested. """ RuleCheck = _checks.RuleCheck """Recursively checks credentials based on the defined rules.""" class PolicyNotAuthorized(Exception): """Default exception raised for policy enforcement failure.""" def __init__(self, rule, target, creds): msg = _("%(rule)s is disallowed by policy") % {'rule': rule} super(PolicyNotAuthorized, self).__init__(msg) class InvalidScope(Exception): """Raised when the scope of the request mismatches the policy scope.""" def __init__(self, rule, operation_scopes, token_scope): msg = ( "%(rule)s requires a scope of %(operation_scopes)s, request " "was made with %(token_scope)s scope." % { 'rule': rule, 'operation_scopes': operation_scopes, 'token_scope': token_scope } ) super(InvalidScope, self).__init__(msg) class DuplicatePolicyError(Exception): def __init__(self, name): msg = _('Policy %(name)s is already registered') % {'name': name} super(DuplicatePolicyError, self).__init__(msg) class PolicyNotRegistered(Exception): def __init__(self, name): msg = _('Policy %(name)s has not been registered') % {'name': name} super(PolicyNotRegistered, self).__init__(msg) class InvalidDefinitionError(Exception): def __init__(self, names): msg = _('Policies %(names)s are not well defined. Check logs for ' 'more details.') % {'names': names} super(InvalidDefinitionError, self).__init__(msg) class InvalidRuleDefault(Exception): def __init__(self, error): msg = (_('Invalid policy rule default: ' '%(error)s.') % {'error': error}) super(InvalidRuleDefault, self).__init__(msg) class InvalidContextObject(Exception): def __init__(self, error): msg = (_('Invalid context object: ' '%(error)s.') % {'error': error}) super(InvalidContextObject, self).__init__(msg) def parse_file_contents(data): """Parse the raw contents of a policy file. Parses the contents of a policy file which currently can be in either yaml or json format. Both can be parsed as yaml. :param data: A string containing the contents of a policy file. :returns: A dict of the form {'policy_name1': 'policy1', 'policy_name2': 'policy2,...} """ try: # NOTE(snikitin): jsonutils.loads() is much faster than # yaml.safe_load(). However jsonutils.loads() parses only JSON while # yaml.safe_load() parses JSON and YAML. So here we try to parse data # by jsonutils.loads() first. In case of failure yaml.safe_load() # will be used instead. parsed = jsonutils.loads(data) except ValueError: try: parsed = yaml.safe_load(data) except yaml.YAMLError as e: # For backwards-compatibility, convert yaml error to ValueError, # which is what JSON loader raised. raise ValueError(six.text_type(e)) return parsed or {} class Rules(dict): """A store for rules. Handles the default_rule setting directly.""" @classmethod def load(cls, data, default_rule=None): """Allow loading of YAML/JSON rule data. .. versionadded:: 1.5.0 """ parsed_file = parse_file_contents(data) # Parse the rules rules = {k: _parser.parse_rule(v) for k, v in parsed_file.items()} return cls(rules, default_rule) @classmethod def load_json(cls, data, default_rule=None): """Allow loading of YAML/JSON rule data. .. warning:: This method is deprecated as of the 1.5.0 release in favor of :meth:`load` and may be removed in the 2.0 release. """ warnings.warn( 'The load_json() method is deprecated as of the 1.5.0 release in ' 'favor of load() and may be removed in the 2.0 release.', DeprecationWarning) return cls.load(data, default_rule) @classmethod def from_dict(cls, rules_dict, default_rule=None): """Allow loading of rule data from a dictionary.""" # Parse the rules stored in the dictionary rules = {k: _parser.parse_rule(v) for k, v in rules_dict.items()} return cls(rules, default_rule) def __init__(self, rules=None, default_rule=None): """Initialize the Rules store.""" super(Rules, self).__init__(rules or {}) self.default_rule = default_rule 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: raise KeyError(key) if isinstance(self.default_rule, _checks.BaseCheck): return self.default_rule # We need to check this or we can get infinite recursion if self.default_rule not in self: raise KeyError(key) elif isinstance(self.default_rule, six.string_types): return self[self.default_rule] def __str__(self): """Dumps a string representation of the rules.""" # Start by building the canonical strings for the rules out_rules = {} for key, value in self.items(): # Use empty string for singleton TrueCheck instances if isinstance(value, _checks.TrueCheck): out_rules[key] = '' else: out_rules[key] = str(value) # Dump a pretty-printed JSON representation return jsonutils.dumps(out_rules, indent=4) class Enforcer(object): """Responsible for loading and enforcing rules. :param conf: A configuration object. :param policy_file: Custom policy file to use, if none is specified, ``conf.oslo_policy.policy_file`` will be used. :param rules: Default dictionary / Rules to use. It will be considered just in the first instantiation. If :meth:`load_rules` with ``force_reload=True``, :meth:`clear` or :meth:`set_rules` with ``overwrite=True`` is called this will be overwritten. :param default_rule: Default rule to use, conf.default_rule will be used if none is specified. :param use_conf: Whether to load rules from cache or config file. :param overwrite: Whether to overwrite existing rules when reload rules from config file. """ def __init__(self, conf, policy_file=None, rules=None, default_rule=None, use_conf=True, overwrite=True): self.conf = conf opts._register(conf) self.default_rule = (default_rule or self.conf.oslo_policy.policy_default_rule) self.rules = Rules(rules, self.default_rule) self.registered_rules = {} self.file_rules = {} self.policy_path = None self.policy_file = policy_file or self.conf.oslo_policy.policy_file self.use_conf = use_conf self._need_check_rule = True self.overwrite = overwrite self._loaded_files = [] self._policy_dir_mtimes = {} self._file_cache = {} self._informed_no_policy_file = False def set_rules(self, rules, overwrite=True, use_conf=False): """Create a new :class:`Rules` based on the provided dict of rules. :param dict rules: New rules to use. :param overwrite: Whether to overwrite current rules or update them with the new rules. :param use_conf: Whether to reload rules from cache or config file. """ if not isinstance(rules, dict): raise TypeError(_('Rules must be an instance of dict or Rules, ' 'got %s instead') % type(rules)) self.use_conf = use_conf self._need_check_rule = True if overwrite: self.rules = Rules(rules, self.default_rule) else: self.rules.update(rules) def clear(self): """Clears :class:`Enforcer` contents. This will clear this instances rules, policy's cache, file cache and policy's path. """ self.set_rules({}) self.default_rule = None self.policy_path = None self._loaded_files = [] self._policy_dir_mtimes = {} self._file_cache.clear() self.registered_rules = {} self.file_rules = {} self._informed_no_policy_file = False 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 reload rules from config file. """ if force_reload: self.use_conf = force_reload if self.use_conf: if not self.policy_path: try: self.policy_path = self._get_policy_path(self.policy_file) except cfg.ConfigFilesNotFoundError: if not self._informed_no_policy_file: LOG.debug('The policy file %s could not be found.', self.policy_file) self._informed_no_policy_file = True if self.policy_path: self._load_policy_file(self.policy_path, force_reload, overwrite=self.overwrite) for path in self.conf.oslo_policy.policy_dirs: try: path = self._get_policy_path(path) except cfg.ConfigFilesNotFoundError: continue if (force_reload or self._is_directory_updated( self._policy_dir_mtimes, path)): self._walk_through_policy_directory(path, self._load_policy_file, force_reload, False) for default in self.registered_rules.values(): if default.deprecated_for_removal: self._emit_deprecated_for_removal_warning(default) elif default.deprecated_rule: self._handle_deprecated_rule(default) if default.name not in self.rules: self.rules[default.name] = default.check # Detect and log obvious incorrect rule definitions if self._need_check_rule: self.check_rules() self._need_check_rule = False def check_rules(self, raise_on_violation=False): """Look for rule definitions that are obviously incorrect.""" undefined_checks = [] cyclic_checks = [] violation = False for name, check in self.rules.items(): if self._undefined_check(check): undefined_checks.append(name) violation = True if self._cycle_check(check): cyclic_checks.append(name) violation = True if undefined_checks: LOG.warning('Policies %(names)s reference a rule that is not ' 'defined.', {'names': undefined_checks}) if cyclic_checks: LOG.warning('Policies %(names)s are part of a cyclical ' 'reference.', {'names': cyclic_checks}) if raise_on_violation and violation: raise InvalidDefinitionError(undefined_checks + cyclic_checks) return not violation def _emit_deprecated_for_removal_warning(self, default): # If the policy is being removed completely, we need to let operators # know that the policy is going to be silently ignored in the future # and they can remove it from their overrides since it isn't being # replaced by another policy. if default.name in self.file_rules: warnings.warn( 'Policy "%(policy)s":"%(check_str)s" was deprecated for ' 'removal in %(release)s. Reason: %(reason)s. Its value may be ' 'silently ignored in the future.' % { 'policy': default.name, 'check_str': default.check_str, 'release': default.deprecated_since, 'reason': default.deprecated_reason } ) def _handle_deprecated_rule(self, default): """Handle cases where a policy rule has been deprecated. :param default: an instance of RuleDefault that contains an instance of DeprecatedRule """ deprecated_rule = default.deprecated_rule deprecated_msg = ( 'Policy "%(old_name)s":"%(old_check_str)s" was deprecated in ' '%(release)s in favor of "%(name)s":"%(check_str)s". Reason: ' '%(reason)s. Either ensure your deployment is ready for the new ' 'default or copy/paste the deprecated policy into your policy ' 'file and maintain it manually.' % { 'old_name': deprecated_rule.name, 'old_check_str': deprecated_rule.check_str, 'release': default.deprecated_since, 'name': default.name, 'check_str': default.check_str, 'reason': default.deprecated_reason } ) # Print a warning because the actual policy name is changing. If # operators are relying on an override for foo:bar and it's getting # renamed to foo:create_bar then they need to be able to see that # before they roll out the next release. If the policy name is in # self.file_rules, we know that it's being overridden. if deprecated_rule.name != default.name and ( deprecated_rule.name in self.file_rules): warnings.warn(deprecated_msg) # If the deprecated policy is being overridden and doesn't match # the default deprecated policy, override the new policy's default # with the old check string. This should prevents unwanted exposure # to APIs on upgrade. # There's one exception to this: When we generate a sample policy, # we set the deprecated rule name to reference the new rule. If we # see that the deprecated override rule is just the new rule, then # we shouldn't mess with it. if (self.file_rules[deprecated_rule.name].check != _parser.parse_rule(deprecated_rule.check_str) and str(self.file_rules[deprecated_rule.name].check) != 'rule:%s' % default.name): if default.name not in self.file_rules.keys(): self.rules[default.name] = self.file_rules[ deprecated_rule.name ].check # In this case, the default check string is changing. We need to let # operators know that this is going to change. If they don't want to # override it, they are going to have to make sure the right # infrastructure exists before they upgrade. This overrides the new # check with an OrCheck that combines the new and old check_str # attributes from the new and deprecated policies. This will make it so # that deployments don't break on upgrade, but they receive log # messages telling them stuff is going to change if they don't maintain # the policy manually or add infrastructure to their deployment to # support the new policy. if (deprecated_rule.check_str != default.check_str and default.name not in self.file_rules): default.check = _parser.parse_rule( default.check_str + ' or ' + deprecated_rule.check_str ) warnings.warn(deprecated_msg) def _undefined_check(self, check): '''Check if a RuleCheck references an undefined rule.''' if isinstance(check, RuleCheck): if check.match not in self.rules: # Undefined rule return True # An AndCheck or OrCheck is composed of multiple rules so check # each of those. rules = getattr(check, 'rules', None) if rules: for rule in rules: if self._undefined_check(rule): return True return False def _cycle_check(self, check, seen=None): '''Check if RuleChecks cycle. Looking for something like: "foo": "rule:bar" "bar": "rule:foo" ''' if seen is None: seen = set() if isinstance(check, RuleCheck): if check.match in seen: # Cycle found return True seen.add(check.match) if check.match in self.rules: # There can only be a cycle if the referenced rule is defined. if self._cycle_check(self.rules[check.match], seen): return True # An AndCheck or OrCheck is composed of multiple rules so check # each of those. rules = getattr(check, 'rules', None) if rules: for rule in rules: # As there being an OrCheck or AndCheck, a copy of the father's # seen should be called here. In order that the checks in # different branchs are seperated. if self._cycle_check(rule, seen.copy()): return True return False @staticmethod def _is_directory_updated(cache, path): # Get the current modified time and compare it to what is in # the cache and check if the new mtime is greater than what # is in the cache mtime = 0 if os.path.exists(path): # Make a list of all the files files = [path] + [os.path.join(path, file) for file in os.listdir(path)] # Pick the newest one, let's use its time. mtime = os.path.getmtime(max(files, key=os.path.getmtime)) cache_info = cache.setdefault(path, {}) if mtime > cache_info.get('mtime', 0): cache_info['mtime'] = mtime return True return False @staticmethod def _walk_through_policy_directory(path, func, *args): if not os.path.isdir(path): raise ValueError('%s is not a directory' % path) # We do not iterate over sub-directories. policy_files = next(os.walk(path))[2] policy_files.sort() for policy_file in [p for p in policy_files if not p.startswith('.')]: func(os.path.join(path, policy_file), *args) def _record_file_rules(self, data, overwrite=False): """Store a copy of rules loaded from a file. It is useful to be able to distinguish between rules loaded from a file and those registered by a consuming service. In order to do so we keep a record of rules loaded from a file. :param data: The raw contents of a policy file. :param overwrite: If True clear out previously loaded rules. """ if overwrite: self.file_rules = {} parsed_file = parse_file_contents(data) for name, check_str in parsed_file.items(): self.file_rules[name] = RuleDefault(name, check_str) def _load_policy_file(self, path, force_reload, overwrite=True): reloaded, data = _cache_handler.read_cached_file( self._file_cache, path, force_reload=force_reload) if reloaded or not self.rules: rules = Rules.load(data, self.default_rule) self.set_rules(rules, overwrite=overwrite, use_conf=True) self._record_file_rules(data, overwrite) self._loaded_files.append(path) LOG.debug('Reloaded policy file: %(path)s', {'path': path}) def _get_policy_path(self, path): """Locate the policy YAML/JSON data file/path. :param path: It's value can be a full path or related path. When full path specified, this function just returns the full path. When related path specified, this function will search configuration directories to find one that exists. :returns: The policy path :raises: ConfigFilesNotFoundError if the file/path couldn't be located. """ policy_path = self.conf.find_file(path) if policy_path: return policy_path raise cfg.ConfigFilesNotFoundError((path,)) 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: The rule to evaluate. :type rule: string or :class:`BaseCheck` :param dict target: As much information about the object being operated on as possible. The target argument should be a dict instance or an instance of a class that fully supports the Mapping abstract base class and deep copying. :param dict creds: As much information about the user performing the action as possible. This parameter can also be an instance of ``oslo_context.context.RequestContext``. :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 :meth:`enforce` (both positional and keyword arguments) will be passed to the exception class. If not specified, :class:`PolicyNotAuthorized` will be used. :return: ``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. """ self.load_rules() if isinstance(creds, context.RequestContext): creds = self._map_context_attributes_into_creds(creds) # NOTE(lbragstad): The oslo.context library exposes the ability to call # a method on RequestContext objects that converts attributes of the # context object to policy values. However, ``to_policy_values()`` # doesn't actually return a dictionary, it's a subclass of # collections.MutableMapping, which behaves like a dictionary but # doesn't pass the type check. elif not isinstance(creds, collections.MutableMapping): msg = ( 'Expected type oslo_context.context.RequestContext, dict, or ' 'the output of ' 'oslo_context.context.RequestContext.to_policy_values but ' 'got %(creds_type)s instead' % {'creds_type': type(creds)} ) raise InvalidContextObject(msg) if LOG.isEnabledFor(logging.DEBUG): try: # NOTE(jdennis) Although a MutableMapping behaves like # a dict oslo.strutils.mask_dict_password() requires a # dict. Bug #1804528 was opened to fix this, once that # bug is fixed the conversion to dict can be removed. if isinstance(creds, dict): creds_dict = creds elif isinstance(creds, collections.MutableMapping): creds_dict = dict(creds) else: raise TypeError('unexpected type %(creds_type)s' % {'creds_type': type(creds)}) creds_dict = strutils.mask_dict_password( copy.deepcopy(creds_dict) ) creds_msg = jsonutils.dumps(creds_dict, skipkeys=True, sort_keys=True) except Exception as e: creds_msg = ('cannot format data, exception: %(exp)s' % {'exp': e}) try: target_dict = strutils.mask_dict_password( copy.deepcopy(target) ) target_msg = jsonutils.dumps(target_dict, skipkeys=True, sort_keys=True) except Exception as e: target_msg = ('cannot format data, exception: %(exp)s' % {'exp': e}) LOG.debug('enforce: rule=%s creds=%s target=%s', rule.__class__ if isinstance(rule, _checks.BaseCheck) else '"%s"' % rule, creds_msg, target_msg) # Allow the rule to be a Check tree if isinstance(rule, _checks.BaseCheck): # If the thing we're given is a Check, we don't know the # name of the rule, so pass None for current_rule. result = _checks._check( rule=rule, target=target, creds=creds, enforcer=self, current_rule=None, ) elif not self.rules: # No rules to reference means we're going to fail closed result = False else: try: to_check = self.rules[rule] except KeyError: LOG.debug('Rule [%s] does not exist', rule) # If the rule doesn't exist, fail closed result = False else: # Check the scope of the operation against the possible scope # attributes provided in `creds`. if creds.get('system'): token_scope = 'system' elif creds.get('domain_id'): token_scope = 'domain' else: # If the token isn't system-scoped or domain-scoped then # we're dealing with a project-scoped token. token_scope = 'project' registered_rule = self.registered_rules.get(rule) if registered_rule and registered_rule.scope_types: if token_scope not in registered_rule.scope_types: if self.conf.oslo_policy.enforce_scope: raise InvalidScope( rule, registered_rule.scope_types, token_scope ) # If we don't raise an exception we should at least # inform operators about policies that are being used # with improper scopes. msg = ( 'Policy %(rule)s failed scope check. The token ' 'used to make the request was %(token_scope)s ' 'scoped but the policy requires %(policy_scope)s ' 'scope. This behavior may change in the future ' 'where using the intended scope is required' % { 'rule': rule, 'token_scope': token_scope, 'policy_scope': registered_rule.scope_types } ) warnings.warn(msg) result = _checks._check( rule=to_check, target=target, creds=creds, enforcer=self, current_rule=rule, ) # If it is False, raise the exception if requested if do_raise and not result: if exc: raise exc(*args, **kwargs) raise PolicyNotAuthorized(rule, target, creds) return result def _map_context_attributes_into_creds(self, context): creds = {} # port public context attributes into the creds dictionary so long as # the attribute isn't callable context_values = context.to_policy_values() for k, v in context_values.items(): creds[k] = v # NOTE(lbragstad): We unfortunately have to special case this # attribute. Originally when the system scope when into oslo.policy, we # checked for a key called 'system' in creds. The oslo.context library # uses `system_scope` instead, and the compatibility between # oslo.policy and oslo.context was an afterthought. We'll have to # support services who've been setting creds['system'], but we can do # that by making sure we populate it with what's in the context object # if it has a system_scope attribute. if context.system_scope: creds['system'] = context.system_scope return creds def register_default(self, default): """Registers a RuleDefault. Adds a RuleDefault to the list of registered rules. Rules must be registered before using the Enforcer.authorize method. :param default: A RuleDefault object to register. """ if default.name in self.registered_rules: raise DuplicatePolicyError(default.name) self.registered_rules[default.name] = default def register_defaults(self, defaults): """Registers a list of RuleDefaults. Adds each RuleDefault to the list of registered rules. Rules must be registered before using the Enforcer.authorize method. :param default: A list of RuleDefault objects to register. """ for default in defaults: self.register_default(default) def authorize(self, rule, target, creds, do_raise=False, exc=None, *args, **kwargs): """A wrapper around 'enforce' that checks for policy registration. To ensure that a policy being checked has been registered this method should be used rather than enforce. By doing so a project can be sure that all of it's used policies are registered and therefore available for sample file generation. The parameters match the enforce method and a description of them can be found there. """ if rule not in self.registered_rules: raise PolicyNotRegistered(rule) return self.enforce(rule, target, creds, do_raise, exc, *args, **kwargs) class RuleDefault(object): """A class for holding policy definitions. It is required to supply a name and value at creation time. It is encouraged to also supply a description to assist operators. :param name: The name of the policy. This is used when referencing it from another rule or during policy enforcement. :param check_str: The policy. This is a string defining a policy that conforms to the policy language outlined at the top of the file. :param description: A plain text description of the policy. This will be used to comment sample policy files for use by deployers. :param deprecated_rule: :class:`.DeprecatedRule` :param deprecated_for_removal: indicates whether the policy is planned for removal in a future release. :param deprecated_reason: indicates why this policy is planned for removal in a future release. Silently ignored if deprecated_for_removal is False. :param deprecated_since: indicates which release this policy was deprecated in. Accepts any string, though valid version strings are encouraged. Silently ignored if deprecated_for_removal is False. :param scope_types: A list containing the intended scopes of the operation being done. .. versionchanged 1.29 Added *deprecated_rule* parameter. .. versionchanged 1.29 Added *deprecated_for_removal* parameter. .. versionchanged 1.29 Added *deprecated_reason* parameter. .. versionchanged 1.29 Added *deprecated_since* parameter. .. versionchanged 1.31 Added *scope_types* parameter. """ def __init__(self, name, check_str, description=None, deprecated_rule=None, deprecated_for_removal=False, deprecated_reason=None, deprecated_since=None, scope_types=None): self.name = name self.check_str = check_str self.check = _parser.parse_rule(check_str) self.description = description self.deprecated_rule = copy.deepcopy(deprecated_rule) or [] self.deprecated_for_removal = deprecated_for_removal self.deprecated_reason = deprecated_reason self.deprecated_since = deprecated_since if self.deprecated_rule: if not isinstance(self.deprecated_rule, DeprecatedRule): raise ValueError( 'deprecated_rule must be a DeprecatedRule object.' ) if (deprecated_for_removal or deprecated_rule) and ( deprecated_reason is None or deprecated_since is None): raise ValueError( '%(name)s deprecated without deprecated_reason or ' 'deprecated_since. Both must be supplied if deprecating a ' 'policy' % {'name': self.name} ) if scope_types: msg = 'scope_types must be a list of strings.' if not isinstance(scope_types, list): raise ValueError(msg) for scope_type in scope_types: if not isinstance(scope_type, six.string_types): raise ValueError(msg) if scope_types.count(scope_type) > 1: raise ValueError( 'scope_types must be a list of unique strings.' ) self.scope_types = scope_types def __str__(self): return '"%(name)s": "%(check_str)s"' % {'name': self.name, 'check_str': self.check_str} def __eq__(self, other): """Equality operator. All check objects have a stable string representation. It is used for comparison rather than check_str because multiple check_str's may parse to the same check object. For instance '' and '@' are equivalent and the parsed rule string representation for both is '@'. The description does not play a role in the meaning of the check so it is not considered for equality. """ # Name should match, check should match, and class should be equivalent # or one should be a subclass of the other. if (self.name == other.name and str(self.check) == str(other.check) and (isinstance(self, other.__class__) or isinstance(other, self.__class__))): return True return False class DocumentedRuleDefault(RuleDefault): """A class for holding policy-in-code policy objects definitions This class provides the same functionality as the RuleDefault class, but it also requires additional data about the policy rule being registered. This is necessary so that proper documentation can be rendered based on the attributes of this class. Eventually, all usage of RuleDefault should be converted to use DocumentedRuleDefault. :param operations: List of dicts containing each api url and corresponding http request method. Example:: operations=[{'path': '/foo', 'method': 'GET'}, {'path': '/some', 'method': 'POST'}] """ def __init__(self, name, check_str, description, operations, deprecated_rule=None, deprecated_for_removal=False, deprecated_reason=None, deprecated_since=None, scope_types=None): super(DocumentedRuleDefault, self).__init__( name, check_str, description, deprecated_rule=deprecated_rule, deprecated_for_removal=deprecated_for_removal, deprecated_reason=deprecated_reason, deprecated_since=deprecated_since, scope_types=scope_types ) self.operations = operations @property def description(self): return self._description @description.setter def description(self, value): # Validates description isn't empty. if not value: raise InvalidRuleDefault('Description is required') self._description = value @property def operations(self): return self._operations @operations.setter def operations(self, ops): if not isinstance(ops, list): raise InvalidRuleDefault('Operations must be a list') if not ops: raise InvalidRuleDefault('Operations list must not be empty') for op in ops: if 'path' not in op: raise InvalidRuleDefault('Operation must contain a path') if 'method' not in op: raise InvalidRuleDefault('Operation must contain a method') if len(op.keys()) > 2: raise InvalidRuleDefault('Operation contains > 2 keys') self._operations = ops class DeprecatedRule(object): """Represents a Deprecated policy or rule. Here's how you can use it to change a policy's default role or rule. Assume the following policy exists in code:: from oslo_policy import policy policy.DocumentedRuleDefault( name='foo:create_bar', check_str='role:fizz', description='Create a bar.', operations=[{'path': '/v1/bars', 'method': 'POST'}] ) The next snippet will maintain the deprecated option, but allow ``foo:create_bar`` to default to ``role:bang`` instead of ``role:fizz``:: deprecated_rule = policy.DeprecatedRule( name='foo:create_bar', check_str='role:fizz' ) policy.DocumentedRuleDefault( name='foo:create_bar', check_str='role:bang', description='Create a bar.', operations=[{'path': '/v1/bars', 'method': 'POST'}], deprecated_rule=deprecated_rule, deprecated_reason='role:bang is a better default', deprecated_since='N' ) DeprecatedRule can be used to change the policy name itself. Assume the following policy exists in code:: from oslo_policy import policy policy.DocumentedRuleDefault( name='foo:post_bar', check_str='role:fizz', description='Create a bar.', operations=[{'path': '/v1/bars', 'method': 'POST'}] ) For the sake of consistency, let's say we want to replace ``foo:post_bar`` with ``foo:create_bar``, but keep the same ``check_str`` as the default. We can accomplish this by doing:: deprecated_rule = policy.DeprecatedRule( name='foo:post_bar', check_str='role:fizz' ) policy.DocumentedRuleDefault( name='foo:create_bar', check_str='role:fizz', description='Create a bar.', operations=[{'path': '/v1/bars', 'method': 'POST'}], deprecated_rule=deprecated_rule, deprecated_reason='foo:create_bar is more consistent', deprecated_since='N' ) Finally, let's use DeprecatedRule to break a policy into more granular policies. Let's assume the following policy exists in code:: policy.DocumentedRuleDefault( name='foo:bar', check_str='role:bazz', description='Create, read, update, or delete a bar.', operations=[ { 'path': '/v1/bars', 'method': 'POST' }, { 'path': '/v1/bars', 'method': 'GET' }, { 'path': '/v1/bars/{bar_id}', 'method': 'GET' }, { 'path': '/v1/bars/{bar_id}', 'method': 'PATCH' }, { 'path': '/v1/bars/{bar_id}', 'method': 'DELETE' } ] ) Here we can see the same policy is used to protect multiple operations on bars. This prevents operators from being able to assign different roles to different actions that can be taken on bar. For example, what if an operator wanted to require a less restrictive role or rule to list bars but a more restrictive rule to delete them? The following will introduce a policy that helps achieve that and deprecate the original, overly-broad policy:: deprecated_rule = policy.DeprecatedRule( name='foo:bar', check_str='role:bazz' ) policy.DocumentedRuleDefault( name='foo:create_bar', check_str='role:bang', description='Create a bar.', operations=[{'path': '/v1/bars', 'method': 'POST'}], deprecated_rule=deprecated_rule, deprecated_reason='foo:create_bar is more granular than foo:bar', deprecated_since='N' ) policy.DocumentedRuleDefault( name='foo:list_bars', check_str='role:bazz', description='List bars.', operations=[{'path': '/v1/bars', 'method': 'GET'}], deprecated_rule=deprecated_rule, deprecated_reason='foo:list_bars is more granular than foo:bar', deprecated_since='N' ) policy.DocumentedRuleDefault( name='foo:get_bar', check_str='role:bazz', description='Get a bar.', operations=[{'path': '/v1/bars/{bar_id}', 'method': 'GET'}], deprecated_rule=deprecated_rule, deprecated_reason='foo:get_bar is more granular than foo:bar', deprecated_since='N' ) policy.DocumentedRuleDefault( name='foo:update_bar', check_str='role:bang', description='Update a bar.', operations=[{'path': '/v1/bars/{bar_id}', 'method': 'PATCH'}], deprecated_rule=deprecated_rule, deprecated_reason='foo:update_bar is more granular than foo:bar', deprecated_since='N' ) policy.DocumentedRuleDefault( name='foo:delete_bar', check_str='role:bang', description='Delete a bar.', operations=[{'path': '/v1/bars/{bar_id}', 'method': 'DELETE'}], deprecated_rule=deprecated_rule, deprecated_reason='foo:delete_bar is more granular than foo:bar', deprecated_since='N' ) .. versionchanged 1.29 Added *DeprecatedRule* object. """ def __init__(self, name, check_str): """Construct a DeprecatedRule object. :param name: the policy name :param check_str: the value of the policy's check string """ self.name = name self.check_str = check_str