diff --git a/etc/tuskar/tuskar.conf.sample b/etc/tuskar/tuskar.conf.sample index acbe89bb..a8be9574 100644 --- a/etc/tuskar/tuskar.conf.sample +++ b/etc/tuskar/tuskar.conf.sample @@ -168,18 +168,6 @@ #syslog_log_facility=LOG_USER -# -# Options defined in tuskar.openstack.common.policy -# - -# The JSON file that defines policies. (string value) -#policy_file=policy.json - -# Default rule. Enforced when a requested rule is not found. -# (string value) -#policy_default_rule=default - - # # Options defined in tuskar.storage.drivers.sqlalchemy # diff --git a/tuskar/openstack/common/policy.py b/tuskar/openstack/common/policy.py deleted file mode 100644 index e45edb11..00000000 --- a/tuskar/openstack/common/policy.py +++ /dev/null @@ -1,898 +0,0 @@ -# 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 can be expressed in one of two forms: A list of lists, or a -string written in the new policy language. - -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. This is the original way of -expressing policies, but there now exists a new way: the policy -language. - -In the policy language, each check is specified the same way as in the -list-of-lists representation: a simple "a:b" pair that is matched to -the correct code to perform that check. However, conjunction -operators are available, allowing for more expressiveness in crafting -policies. - -As an example, take the following rule, expressed in the list-of-lists -representation:: - - [["role:admin"], ["project_id:%(project_id)s", "role:projectadmin"]] - -In the policy language, this becomes:: - - 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 - -It is possible to perform policy checks on the following user -attributes (obtained through the token): user_id, domain_id or -project_id:: - - domain_id: - -Attributes sent along with API calls can be used by the policy engine -(on the right side of the expression), by using the following syntax:: - - :user.id - -Contextual attributes of objects identified by their IDs are loaded -from the database. They are also available to the policy engine and -can be checked through the `target` keyword:: - - :target.role.name - -All of these attributes (related to users, API calls, and context) can be -checked against each other or against constants, be it literals (True, -) or strings. - -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. -""" - -import abc -import ast -import re - -from oslo.config import cfg -import six -import six.moves.urllib.parse as urlparse -import six.moves.urllib.request as urlrequest - -from tuskar.openstack.common import fileutils -from tuskar.openstack.common.gettextutils import _, _LE -from tuskar.openstack.common import jsonutils -from tuskar.openstack.common import log as logging - - -policy_opts = [ - cfg.StrOpt('policy_file', - default='policy.json', - help=_('The JSON file that defines policies.')), - cfg.StrOpt('policy_default_rule', - default='default', - help=_('Default rule. Enforced when a requested rule is not ' - 'found.')), -] - -CONF = cfg.CONF -CONF.register_opts(policy_opts) - -LOG = logging.getLogger(__name__) - -_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.""" - - @classmethod - def load_json(cls, data, default_rule=None): - """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 - jsonutils.loads(data).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, 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, 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 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. - :param use_conf: Whether to load rules from cache or config file. - """ - - def __init__(self, policy_file=None, rules=None, - default_rule=None, use_conf=True): - 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 - self.use_conf = use_conf - - def set_rules(self, rules, overwrite=True, use_conf=False): - """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. - :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 - 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 force_reload: - self.use_conf = force_reload - - if self.use_conf: - 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((self.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 do_raise and not result: - if exc: - raise exc(*args, **kwargs) - - raise PolicyNotAuthorized(rule) - - return result - - -@six.add_metaclass(abc.ABCMeta) -class BaseCheck(object): - """Abstract base class for Check classes.""" - - @abc.abstractmethod - def __str__(self): - """String representation of the Check tree rooted at this node.""" - - pass - - @abc.abstractmethod - 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. - """ - - pass - - -class FalseCheck(BaseCheck): - """A policy check that always returns False (disallow).""" - - def __str__(self): - """Return a string representation of this check.""" - - return "!" - - def __call__(self, target, cred, enforcer): - """Check the policy.""" - - return False - - -class TrueCheck(BaseCheck): - """A policy check that always returns True (allow).""" - - def __str__(self): - """Return a string representation of this check.""" - - return "@" - - def __call__(self, target, cred, enforcer): - """Check the policy.""" - - return True - - -class Check(BaseCheck): - """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 - the ':'. - """ - - self.kind = kind - self.match = match - - def __str__(self): - """Return a string representation of this check.""" - - return "%s:%s" % (self.kind, self.match) - - -class NotCheck(BaseCheck): - """Implements the "not" logical operator. - - A policy check that inverts the result of another policy check. - """ - - def __init__(self, rule): - """Initialize the 'not' check. - - :param rule: The rule to negate. Must be a Check. - """ - - self.rule = rule - - def __str__(self): - """Return a string representation of this check.""" - - return "not %s" % self.rule - - def __call__(self, target, cred, enforcer): - """Check the policy. - - Returns the logical inverse of the wrapped check. - """ - - return not self.rule(target, cred, enforcer) - - -class AndCheck(BaseCheck): - """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. - - :param rules: A list of rules that will be tested. - """ - - self.rules = rules - - def __str__(self): - """Return a string representation of this check.""" - - return "(%s)" % ' and '.join(str(r) for r in self.rules) - - 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, 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. - """ - - self.rules.append(rule) - return self - - -class OrCheck(BaseCheck): - """Implements the "or" operator. - - A policy check that requires that at least one of a list of other - checks returns True. - """ - - def __init__(self, rules): - """Initialize the 'or' check. - - :param rules: A list of rules that will be tested. - """ - - self.rules = rules - - def __str__(self): - """Return a string representation of this check.""" - - return "(%s)" % ' or '.join(str(r) for r in self.rules) - - 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, 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. - """ - - self.rules.append(rule) - return self - - -def _parse_check(rule): - """Parse a single base check rule into an appropriate Check object.""" - - # Handle the special checks - if rule == '!': - return FalseCheck() - elif rule == '@': - return TrueCheck() - - try: - kind, match = rule.split(':', 1) - except Exception: - LOG.exception(_LE("Failed to understand rule %s") % rule) - # If the rule is invalid, we'll fail closed - return FalseCheck() - - # Find what implements the check - if kind in _checks: - return _checks[kind](kind, match) - elif None in _checks: - return _checks[None](kind, match) - else: - LOG.error(_LE("No handler for matches of kind %s") % kind) - return FalseCheck() - - -def _parse_list_rule(rule): - """Translates the old list-of-lists syntax into a tree of Check objects. - - Provided for backwards compatibility. - """ - - # Empty rule defaults to True - if not rule: - return TrueCheck() - - # Outer list is joined by "or"; inner list by "and" - or_list = [] - for inner_rule in rule: - # Elide empty inner lists - if not inner_rule: - continue - - # Handle bare strings - if isinstance(inner_rule, six.string_types): - inner_rule = [inner_rule] - - # Parse the inner rules into Check objects - and_list = [_parse_check(r) for r in inner_rule] - - # Append the appropriate check to the or_list - if len(and_list) == 1: - or_list.append(and_list[0]) - else: - or_list.append(AndCheck(and_list)) - - # If we have only one check, omit the "or" - if not or_list: - return FalseCheck() - elif len(or_list) == 1: - return or_list[0] - - return OrCheck(or_list) - - -# Used for tokenizing the policy language -_tokenize_re = re.compile(r'\s+') - - -def _parse_tokenize(rule): - """Tokenizer for the policy language. - - Most of the single-character tokens are specified in the - _tokenize_re; however, parentheses need to be handled specially, - because they can appear inside a check string. Thankfully, those - parentheses that appear inside a check string can never occur at - the very beginning or end ("%(variable)s" is the correct syntax). - """ - - for tok in _tokenize_re.split(rule): - # Skip empty tokens - if not tok or tok.isspace(): - continue - - # Handle leading parens on the token - clean = tok.lstrip('(') - for i in range(len(tok) - len(clean)): - yield '(', '(' - - # If it was only parentheses, continue - if not clean: - continue - else: - tok = clean - - # Handle trailing parens on the token - clean = tok.rstrip(')') - trail = len(tok) - len(clean) - - # Yield the cleaned token - lowered = clean.lower() - if lowered in ('and', 'or', 'not'): - # Special tokens - yield lowered, clean - elif clean: - # Not a special token, but not composed solely of ')' - if len(tok) >= 2 and ((tok[0], tok[-1]) in - [('"', '"'), ("'", "'")]): - # It's a quoted string - yield 'string', tok[1:-1] - else: - yield 'check', _parse_check(clean) - - # Yield the trailing parens - for i in range(trail): - yield ')', ')' - - -class ParseStateMeta(type): - """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. - """ - - reducers = [] - - for key, value in cls_dict.items(): - if not hasattr(value, 'reducers'): - continue - for reduction in value.reducers: - reducers.append((reduction, key)) - - cls_dict['reducers'] = reducers - - return super(ParseStateMeta, mcs).__new__(mcs, name, bases, cls_dict) - - -def reducer(*tokens): - """Decorator for reduction methods. - - Arguments are a sequence of tokens, in order, which should trigger running - this reduction method. - """ - - def decorator(func): - # Make sure we have a list of reducer sequences - if not hasattr(func, 'reducers'): - func.reducers = [] - - # Add the tokens to the list of reducer sequences - func.reducers.append(list(tokens)) - - return func - - return decorator - - -@six.add_metaclass(ParseStateMeta) -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. - - Note: error reporting is rather lacking. The best we can get with - this parser formulation is an overall "parse failed" error. - Fortunately, the policy language is simple enough that this - shouldn't be that big a problem. - """ - - def __init__(self): - """Initialize the ParseState.""" - - self.tokens = [] - 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. - """ - - 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) - - # 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] - - # Check for any more reductions - return self.reduce() - - def shift(self, tok, value): - """Adds one more token to the state. Calls reduce().""" - - self.tokens.append(tok) - self.values.append(value) - - # Do a greedy reduce... - self.reduce() - - @property - def result(self): - """Obtain the final result of the parse. - - Raises ValueError if the parse failed to reduce to a single result. - """ - - if len(self.values) != 1: - raise ValueError("Could not parse rule") - return self.values[0] - - @reducer('(', 'check', ')') - @reducer('(', 'and_expr', ')') - @reducer('(', 'or_expr', ')') - def _wrap_check(self, _p1, check, _p2): - """Turn parenthesized expressions into a 'check' token.""" - - return [('check', check)] - - @reducer('check', 'and', 'check') - def _make_and_expr(self, check1, _and, check2): - """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.""" - - return [('and_expr', and_expr.add_check(check))] - - @reducer('check', 'or', 'check') - def _make_or_expr(self, check1, _or, check2): - """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.""" - - return [('or_expr', or_expr.add_check(check))] - - @reducer('not', 'check') - def _make_not_expr(self, _not, check): - """Invert the result of another check.""" - - return [('check', NotCheck(check))] - - -def _parse_text_rule(rule): - """Parses policy to the tree. - - Translates a policy written in the policy language into a tree of - Check objects. - """ - - # Empty rule means always accept - if not rule: - return TrueCheck() - - # Parse the token stream - state = ParseState() - for tok, value in _parse_tokenize(rule): - state.shift(tok, value) - - try: - return state.result - except ValueError: - # Couldn't parse the rule - LOG.exception(_LE("Failed to understand rule %r") % rule) - - # Fail closed - return FalseCheck() - - -def parse_rule(rule): - """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, six.string_types): - return _parse_text_rule(rule) - return _parse_list_rule(rule) - - -def register(name, func=None): - """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 - 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. - """ - - # Perform the actual decoration by registering the function or - # class. Returns the function or class for compliance with the - # decorator interface. - def decorator(func): - _checks[name] = func - return func - - # If the function or class is given, do the registration - if func: - return decorator(func) - - return decorator - - -@register("rule") -class RuleCheck(Check): - def __call__(self, target, creds, enforcer): - """Recursively checks credentials based on the defined rules.""" - - try: - return enforcer.rules[self.match](target, creds, enforcer) - except KeyError: - # We don't have any matching rule; fail closed - return False - - -@register("role") -class RoleCheck(Check): - 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']] - - -@register('http') -class HttpCheck(Check): - 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'. - """ - - url = ('http:' + self.match) % target - data = {'target': jsonutils.dumps(target), - 'credentials': jsonutils.dumps(creds)} - post_data = urlparse.urlencode(data) - f = urlrequest.urlopen(url, post_data) - return f.read() == "True" - - -@register(None) -class GenericCheck(Check): - def __call__(self, target, creds, enforcer): - """Check an individual match. - - Matches look like: - - tenant:%(tenant_id)s - role:compute:admin - True:%(user.enabled)s - 'Member':%(role.name)s - """ - - # TODO(termie): do dict inspection via dot syntax - try: - match = self.match % target - except KeyError: - # While doing GenericCheck if key not - # present in Target return false - return False - - try: - # Try to interpret self.kind as a literal - leftval = ast.literal_eval(self.kind) - except ValueError: - try: - leftval = creds[self.kind] - except KeyError: - return False - return match == six.text_type(leftval)