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

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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
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12
passbook/core/models.py
View file

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

94
passbook/policies/expression/evaluator.py
View file

@ -1,8 +1,9 @@
"""passbook expression policy evaluator"""
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.http import HttpRequest
from jinja2 import Undefined
from jinja2.exceptions import TemplateSyntaxError
from jinja2.nativetypes import NativeEnvironment
@ -25,12 +26,32 @@ class Evaluator:
_env: NativeEnvironment
_context: Dict[str, Any]
_messages: List[str]
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 docs/policies/expression/index.md
self._env.filters["regex_match"] = Evaluator.jinja2_filter_regex_match
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
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`"""
return user.groups.filter(name=group_name).exists()
def _get_expression_context(
self, request: PolicyRequest, **kwargs
) -> Dict[str, Any]:
"""Return dictionary with additional global variables passed to expression"""
def jinja2_func_message(self, message: str):
"""Wrapper to append to messages list, which is returned with PolicyResult"""
self._messages.append(message)
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 docs/policies/expression/index.md
kwargs["pb_is_group_member"] = Evaluator.jinja2_func_is_group_member
kwargs["pb_logger"] = get_logger()
kwargs["requests"] = Session()
kwargs["pb_is_sso_flow"] = request.context.get(PLAN_CONTEXT_SSO, False)
self._context["pb_is_sso_flow"] = request.context.get(PLAN_CONTEXT_SSO, False)
self._context["request"] = request
if request.http_request:
kwargs["pb_client_ip"] = (
get_client_ip(request.http_request) or "255.255.255.255"
)
if SESSION_KEY_PLAN in request.http_request.session:
kwargs["pb_flow_plan"] = request.http_request.session[SESSION_KEY_PLAN]
return kwargs
self.set_http_request(request.http_request)
def evaluate(self, expression_source: str, request: PolicyRequest) -> PolicyResult:
"""Parse and evaluate expression.
If the Expression evaluates to a list with 2 items, the first is used as passing bool and
the second as messages.
If the Expression evaluates to a truthy-object, it is used as passing bool."""
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"
)
self._context["request"] = request
if SESSION_KEY_PLAN in request.http_request.session:
self._context["pb_flow_plan"] = request.http_request.session[
SESSION_KEY_PLAN
]
def evaluate(self, expression_source: str) -> PolicyResult:
"""Parse and evaluate expression. Policy is expected to return a truthy object.
Messages can be added using 'do pb_message()'."""
try:
expression = self._env.from_string(expression_source)
expression = self._env.from_string(expression_source.lstrip().rstrip())
except TemplateSyntaxError as exc:
return PolicyResult(False, str(exc))
try:
result: Optional[Any] = expression.render(
request=request, **self._get_expression_context(request)
)
result: Optional[Any] = expression.render(self._context)
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):
LOGGER.warning(
"Expression policy returned undefined",
src=expression_source,
req=request,
req=self._context,
)
return PolicyResult(False)
if isinstance(result, (list, tuple)) and len(result) == 2:
return PolicyResult(*result)
policy_result.passing = False
if result:
return PolicyResult(bool(result))
return PolicyResult(False)
except Exception as exc: # pylint: disable=broad-except
LOGGER.warning("Expression error", exc=exc)
return PolicyResult(False, str(exc))
policy_result.passing = bool(result)
return policy_result
def validate(self, expression: str):
"""Validate expression's syntax, raise ValidationError if Syntax is invalid"""

4
passbook/policies/expression/models.py
View file

@ -16,7 +16,9 @@ class ExpressionPolicy(Policy):
def passes(self, request: PolicyRequest) -> PolicyResult:
"""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):
Evaluator().validate(self.expression)

14
passbook/policies/expression/tests/test_evaluator.py
View file

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