improve minimize performance

policy_sentry/writing/minimize.py

@@ -21,59 +21,56 @@
 * For managed policies: You can add up to 10 managed policies to a user, role, or group.
 * The size of each managed policy cannot exceed 6,144 characters.
 """
+from __future__ import annotations
+
 import logging
 import functools
 
-# from policyuniverse.expander_minimizer import _get_prefixes_for_action
-
 logger = logging.getLogger(__name__)
 
 
 # Borrowed from policyuniverse to reduce size
 # https://github.com/Netflix-Skunkworks/policyuniverse/blob/master/policyuniverse/expander_minimizer.py#L45
 @functools.lru_cache(maxsize=1024)
-def _get_prefixes_for_action(action):
+def _get_prefixes_for_action(action: str) -> list[str]:
     """
     :param action: iam:cat
     :return: [ "iam:", "iam:c", "iam:ca", "iam:cat" ]
     """
-    (technology, permission) = action.split(":")
-    retval = ["{}:".format(technology)]
-    phrase = ""
-    for char in permission:
-        newphrase = "{}{}".format(phrase, char)
-        retval.append("{}:{}".format(technology, newphrase))
-        phrase = newphrase
+    technology, permission = action.split(":")
+    retval = [f"{technology}:{permission[:i]}" for i in range(len(permission) + 1)]
+
     return retval
 
 
 # Adapted version of policyuniverse's _get_denied_prefixes_from_desired, here:
 # https://github.com/Netflix-Skunkworks/policyuniverse/blob/master/policyuniverse/expander_minimizer.py#L101
 def get_denied_prefixes_from_desired(
-    desired_actions, all_actions
-):  # pylint: disable=missing-function-docstring
+    desired_actions: list[str], all_actions: set[str]
+) -> set[str]:  # pylint: disable=missing-function-docstring
     """
     Adapted version of policyuniverse's _get_denied_prefixes_from_desired, here: https://github.com/Netflix-Skunkworks/policyuniverse/blob/master/policyuniverse/expander_minimizer.py#L101
     """
     denied_actions = all_actions.difference(desired_actions)
-    denied_prefixes = set()
-    for denied_action in denied_actions:
-        for denied_prefix in _get_prefixes_for_action(denied_action):
-            denied_prefixes.add(denied_prefix)
+    denied_prefixes = {
+        denied_prefix
+        for denied_action in denied_actions
+        for denied_prefix in _get_prefixes_for_action(denied_action)
+    }
 
     return denied_prefixes
 
 
 # Adapted version of policyuniverse's _check_permission_length. We are commenting out the skipping prefix message
 # https://github.com/Netflix-Skunkworks/policyuniverse/blob/master/policyuniverse/expander_minimizer.py#L111
 def check_min_permission_length(
-    permission, minchars=None
-):  # pylint: disable=missing-function-docstring
+    permission: str, minchars: int | None = None
+) -> bool:  # pylint: disable=missing-function-docstring
     """
     Adapted version of policyuniverse's _check_permission_length. We are commenting out the skipping prefix message
     https://github.com/Netflix-Skunkworks/policyuniverse/blob/master/policyuniverse/expander_minimizer.py#L111
     """
-    if minchars and len(permission) < int(minchars) and permission != "":
+    if minchars and permission and len(permission) < int(minchars):
         # print(
         #     "Skipping prefix {} because length of {}".format(
         #         permission, len(permission)
@@ -87,8 +84,8 @@ def check_min_permission_length(
 # This is a condensed version of policyuniverse's minimize_statement_actions, changed for our purposes.
 # https://github.com/Netflix-Skunkworks/policyuniverse/blob/master/policyuniverse/expander_minimizer.py#L123
 def minimize_statement_actions(
-    desired_actions, all_actions, minchars=None
-):  # pylint: disable=missing-function-docstring
+    desired_actions: list[str], all_actions: set[str], minchars: int | None = None
+) -> list[str]:  # pylint: disable=missing-function-docstring
     """
     This is a condensed version of policyuniverse's minimize_statement_actions, changed for our purposes.
     https://github.com/Netflix-Skunkworks/policyuniverse/blob/master/policyuniverse/expander_minimizer.py#L123
@@ -110,16 +107,16 @@ def minimize_statement_actions(
                 continue
             # If the action name is not empty
             if prefix not in denied_prefixes:
-                if permission != "":
+                if permission:
                     if prefix not in desired_actions:
-                        prefix = "{}*".format(prefix)
+                        prefix = f"{prefix}*"
                     minimized_actions.add(prefix)
                     found_prefix = True
                     break
 
         if not found_prefix:
             logger.debug(
-                "Could not suitable prefix. Defaulting to %s".format(prefixes[-1])
+                f"Could not find suitable prefix. Defaulting to {prefixes[-1]}"
             )
             minimized_actions.add(prefixes[-1])
     # sort the actions

test/writing/test_minimize.py

@@ -1,7 +1,10 @@
 import unittest
 import json
 from policy_sentry.writing.sid_group import SidGroup
-from policy_sentry.writing.minimize import minimize_statement_actions
+from policy_sentry.writing.minimize import (
+    minimize_statement_actions,
+    check_min_permission_length,
+)
 from policy_sentry.querying.all import get_all_actions
 from policy_sentry.util.policy_files import get_sid_names_from_policy, get_statement_from_policy_using_sid
 
@@ -45,6 +48,35 @@ def test_minimize_statement_actions_funky_case(self):
             sorted(desired_result),
         )
 
+    def test_minimize_statement_actions_with_min_chars(self):
+        actions_to_minimize = [
+            "ec2:AuthorizeSecurityGroupEgress",
+            "ec2:AuthorizeSecurityGroupIngress",
+        ]
+        desired_result = ["ec2:authorizesecurity*"]
+        all_actions = get_all_actions(lowercase=True)
+        minchars = 17
+        self.maxDiff = None
+        self.assertListEqual(
+            sorted(
+                minimize_statement_actions(actions_to_minimize, all_actions, minchars)
+            ),
+            sorted(desired_result),
+        )
+
+    def test_minimize_statement_actions_with_wildcard(self):
+        actions_to_minimize = ["ec2:*"]
+        desired_result = ["ec2:*"]
+        all_actions = get_all_actions(lowercase=True)
+        minchars = None
+        self.maxDiff = None
+        self.assertListEqual(
+            sorted(
+                minimize_statement_actions(actions_to_minimize, all_actions, minchars)
+            ),
+            sorted(desired_result),
+        )
+
     def test_minimize_rw_same_one(self):
         cfg = {
             "mode": "crud",