policies/expression: use pb_message() for messages instead of returning a tuple

This commit is contained in:
Jens Langhammer 2020-06-01 15:25:38 +02:00
parent 6ed822fa38
commit 82d12ecfdf
4 changed files with 80 additions and 44 deletions

View File

@ -13,7 +13,6 @@ from django.utils.translation import gettext_lazy as _
from guardian.mixins import GuardianUserMixin from guardian.mixins import GuardianUserMixin
from jinja2 import Undefined from jinja2 import Undefined
from jinja2.exceptions import TemplateSyntaxError, UndefinedError from jinja2.exceptions import TemplateSyntaxError, UndefinedError
from jinja2.nativetypes import NativeEnvironment
from model_utils.managers import InheritanceManager from model_utils.managers import InheritanceManager
from structlog import get_logger from structlog import get_logger
@ -24,7 +23,6 @@ from passbook.lib.models import CreatedUpdatedModel
from passbook.policies.models import PolicyBindingModel from passbook.policies.models import PolicyBindingModel
LOGGER = get_logger() LOGGER = get_logger()
NATIVE_ENVIRONMENT = NativeEnvironment()
def default_token_duration(): def default_token_duration():
@ -208,8 +206,11 @@ class PropertyMapping(models.Model):
self, user: Optional[User], request: Optional[HttpRequest], **kwargs self, user: Optional[User], request: Optional[HttpRequest], **kwargs
) -> Any: ) -> Any:
"""Evaluate `self.expression` using `**kwargs` as Context.""" """Evaluate `self.expression` using `**kwargs` as Context."""
from passbook.policies.expression.evaluator import Evaluator
evaluator = Evaluator()
try: try:
expression = NATIVE_ENVIRONMENT.from_string(self.expression) expression = evaluator.env.from_string(self.expression)
except TemplateSyntaxError as exc: except TemplateSyntaxError as exc:
raise PropertyMappingExpressionException from exc raise PropertyMappingExpressionException from exc
try: try:
@ -221,8 +222,11 @@ class PropertyMapping(models.Model):
raise PropertyMappingExpressionException from exc raise PropertyMappingExpressionException from exc
def save(self, *args, **kwargs): def save(self, *args, **kwargs):
from passbook.policies.expression.evaluator import Evaluator
evaluator = Evaluator()
try: try:
NATIVE_ENVIRONMENT.from_string(self.expression) evaluator.env.from_string(self.expression)
except TemplateSyntaxError as exc: except TemplateSyntaxError as exc:
raise ValidationError("Expression Syntax Error") from exc raise ValidationError("Expression Syntax Error") from exc
return super().save(*args, **kwargs) return super().save(*args, **kwargs)

View File

@ -1,8 +1,9 @@
"""passbook expression policy evaluator""" """passbook expression policy evaluator"""
import re import re
from typing import TYPE_CHECKING, Any, Dict, Optional from typing import TYPE_CHECKING, Any, Dict, List, Optional
from django.core.exceptions import ValidationError from django.core.exceptions import ValidationError
from django.http import HttpRequest
from jinja2 import Undefined from jinja2 import Undefined
from jinja2.exceptions import TemplateSyntaxError from jinja2.exceptions import TemplateSyntaxError
from jinja2.nativetypes import NativeEnvironment from jinja2.nativetypes import NativeEnvironment
@ -25,12 +26,32 @@ class Evaluator:
_env: NativeEnvironment _env: NativeEnvironment
_context: Dict[str, Any]
_messages: List[str]
def __init__(self): def __init__(self):
self._env = NativeEnvironment() self._env = NativeEnvironment(
extensions=["jinja2.ext.do",],
trim_blocks=True,
lstrip_blocks=True,
line_statement_prefix=">",
)
# update passbook/policies/expression/templates/policy/expression/form.html # update passbook/policies/expression/templates/policy/expression/form.html
# update docs/policies/expression/index.md # update docs/policies/expression/index.md
self._env.filters["regex_match"] = Evaluator.jinja2_filter_regex_match self._env.filters["regex_match"] = Evaluator.jinja2_filter_regex_match
self._env.filters["regex_replace"] = Evaluator.jinja2_filter_regex_replace self._env.filters["regex_replace"] = Evaluator.jinja2_filter_regex_replace
self._env.globals["pb_message"] = self.jinja2_func_message
self._context = {
"pb_is_group_member": Evaluator.jinja2_func_is_group_member,
"pb_logger": get_logger(),
"requests": Session(),
}
self._messages = []
@property
def env(self) -> NativeEnvironment:
"""Access to our custom NativeEnvironment"""
return self._env
@staticmethod @staticmethod
def jinja2_filter_regex_match(value: Any, regex: str) -> bool: def jinja2_filter_regex_match(value: Any, regex: str) -> bool:
@ -47,52 +68,57 @@ class Evaluator:
"""Check if `user` is member of group with name `group_name`""" """Check if `user` is member of group with name `group_name`"""
return user.groups.filter(name=group_name).exists() return user.groups.filter(name=group_name).exists()
def _get_expression_context( def jinja2_func_message(self, message: str):
self, request: PolicyRequest, **kwargs """Wrapper to append to messages list, which is returned with PolicyResult"""
) -> Dict[str, Any]: self._messages.append(message)
"""Return dictionary with additional global variables passed to expression"""
def set_policy_request(self, request: PolicyRequest):
"""Update context based on policy request (if http request is given, update that too)"""
# update passbook/policies/expression/templates/policy/expression/form.html # update passbook/policies/expression/templates/policy/expression/form.html
# update docs/policies/expression/index.md # update docs/policies/expression/index.md
kwargs["pb_is_group_member"] = Evaluator.jinja2_func_is_group_member self._context["pb_is_sso_flow"] = request.context.get(PLAN_CONTEXT_SSO, False)
kwargs["pb_logger"] = get_logger() self._context["request"] = request
kwargs["requests"] = Session()
kwargs["pb_is_sso_flow"] = request.context.get(PLAN_CONTEXT_SSO, False)
if request.http_request: if request.http_request:
kwargs["pb_client_ip"] = ( self.set_http_request(request.http_request)
def set_http_request(self, request: HttpRequest):
"""Update context based on http request"""
# update passbook/policies/expression/templates/policy/expression/form.html
# update docs/policies/expression/index.md
self._context["pb_client_ip"] = (
get_client_ip(request.http_request) or "255.255.255.255" get_client_ip(request.http_request) or "255.255.255.255"
) )
self._context["request"] = request
if SESSION_KEY_PLAN in request.http_request.session: if SESSION_KEY_PLAN in request.http_request.session:
kwargs["pb_flow_plan"] = request.http_request.session[SESSION_KEY_PLAN] self._context["pb_flow_plan"] = request.http_request.session[
return kwargs SESSION_KEY_PLAN
]
def evaluate(self, expression_source: str, request: PolicyRequest) -> PolicyResult: def evaluate(self, expression_source: str) -> PolicyResult:
"""Parse and evaluate expression. """Parse and evaluate expression. Policy is expected to return a truthy object.
If the Expression evaluates to a list with 2 items, the first is used as passing bool and Messages can be added using 'do pb_message()'."""
the second as messages.
If the Expression evaluates to a truthy-object, it is used as passing bool."""
try: try:
expression = self._env.from_string(expression_source) expression = self._env.from_string(expression_source.lstrip().rstrip())
except TemplateSyntaxError as exc: except TemplateSyntaxError as exc:
return PolicyResult(False, str(exc)) return PolicyResult(False, str(exc))
try: try:
result: Optional[Any] = expression.render( result: Optional[Any] = expression.render(self._context)
request=request, **self._get_expression_context(request) except Exception as exc: # pylint: disable=broad-except
) LOGGER.warning("Expression error", exc=exc)
return PolicyResult(False, str(exc))
else:
policy_result = PolicyResult(False)
policy_result.messages = tuple(self._messages)
if isinstance(result, Undefined): if isinstance(result, Undefined):
LOGGER.warning( LOGGER.warning(
"Expression policy returned undefined", "Expression policy returned undefined",
src=expression_source, src=expression_source,
req=request, req=self._context,
) )
return PolicyResult(False) policy_result.passing = False
if isinstance(result, (list, tuple)) and len(result) == 2:
return PolicyResult(*result)
if result: if result:
return PolicyResult(bool(result)) policy_result.passing = bool(result)
return PolicyResult(False) return policy_result
except Exception as exc: # pylint: disable=broad-except
LOGGER.warning("Expression error", exc=exc)
return PolicyResult(False, str(exc))
def validate(self, expression: str): def validate(self, expression: str):
"""Validate expression's syntax, raise ValidationError if Syntax is invalid""" """Validate expression's syntax, raise ValidationError if Syntax is invalid"""

View File

@ -16,7 +16,9 @@ class ExpressionPolicy(Policy):
def passes(self, request: PolicyRequest) -> PolicyResult: def passes(self, request: PolicyRequest) -> PolicyResult:
"""Evaluate and render expression. Returns PolicyResult(false) on error.""" """Evaluate and render expression. Returns PolicyResult(false) on error."""
return Evaluator().evaluate(self.expression, request) evaluator = Evaluator()
evaluator.set_policy_request(request)
return evaluator.evaluate(self.expression)
def save(self, *args, **kwargs): def save(self, *args, **kwargs):
Evaluator().validate(self.expression) Evaluator().validate(self.expression)

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@ -17,13 +17,15 @@ class TestEvaluator(TestCase):
"""test simple value expression""" """test simple value expression"""
template = "True" template = "True"
evaluator = Evaluator() evaluator = Evaluator()
self.assertEqual(evaluator.evaluate(template, self.request).passing, True) evaluator.set_policy_request(self.request)
self.assertEqual(evaluator.evaluate(template).passing, True)
def test_messages(self): def test_messages(self):
"""test expression with message return""" """test expression with message return"""
template = "False, 'some message'" template = '{% do pb_message("some message") %}False'
evaluator = Evaluator() evaluator = Evaluator()
result = evaluator.evaluate(template, self.request) evaluator.set_policy_request(self.request)
result = evaluator.evaluate(template)
self.assertEqual(result.passing, False) self.assertEqual(result.passing, False)
self.assertEqual(result.messages, ("some message",)) self.assertEqual(result.messages, ("some message",))
@ -31,7 +33,8 @@ class TestEvaluator(TestCase):
"""test invalid syntax""" """test invalid syntax"""
template = "{%" template = "{%"
evaluator = Evaluator() evaluator = Evaluator()
result = evaluator.evaluate(template, self.request) evaluator.set_policy_request(self.request)
result = evaluator.evaluate(template)
self.assertEqual(result.passing, False) self.assertEqual(result.passing, False)
self.assertEqual(result.messages, ("tag name expected",)) self.assertEqual(result.messages, ("tag name expected",))
@ -39,7 +42,8 @@ class TestEvaluator(TestCase):
"""test undefined result""" """test undefined result"""
template = "{{ foo.bar }}" template = "{{ foo.bar }}"
evaluator = Evaluator() evaluator = Evaluator()
result = evaluator.evaluate(template, self.request) evaluator.set_policy_request(self.request)
result = evaluator.evaluate(template)
self.assertEqual(result.passing, False) self.assertEqual(result.passing, False)
self.assertEqual(result.messages, ("'foo' is undefined",)) self.assertEqual(result.messages, ("'foo' is undefined",))