user management fix

app/ipc.py

@@ -1,6 +1,8 @@
+
 import json
 import os
 import socket
+import sqlite3
 import struct
 import subprocess
 import threading
@@ -16,6 +18,10 @@ BUFFER_SIZE = 65536
 POLKIT_ACTION = "org.sarlink.parentalcontrol.modify"
 
 
+# ============================================================
+# Peer credentials and authorization
+# ============================================================
+
 def get_peer_credentials(connection):
     credentials = connection.getsockopt(
         socket.SOL_SOCKET,
@@ -26,7 +32,19 @@ def get_peer_credentials(connection):
     return struct.unpack("3i", credentials)
 
 
-def authorize_write(pid: int) -> bool:
+def authorize_write(pid: int, uid: int) -> bool:
+    """
+    Authorize administrative operations.
+
+    Root is automatically authorized.
+
+    Non-root users must pass Polkit authorization.
+    """
+
+    # Root is already an administrator.
+    if uid == 0:
+        return True
+
     try:
         os.kill(pid, 0)
     except OSError:
@@ -53,6 +71,10 @@ def authorize_write(pid: int) -> bool:
         return False
 
 
+# ============================================================
+# Database operations
+# ============================================================
+
 class IPCOperations:
 
     @staticmethod
@@ -359,6 +381,10 @@ class IPCOperations:
             )
 
 
+# ============================================================
+# Allowed IPC methods
+# ============================================================
+
 READ_METHODS = {
     "get_users",
     "get_user",
@@ -377,7 +403,15 @@ WRITE_METHODS = {
 }
 
 
-def handle_request(request, pid):
+# ============================================================
+# Request handling
+# ============================================================
+
+def handle_request(
+    request,
+    pid,
+    uid,
+):
     method = request.get("method")
     arguments = request.get("args", {})
 
@@ -396,7 +430,7 @@ def handle_request(request, pid):
         return operation(**arguments)
 
     if method in WRITE_METHODS:
-        if not authorize_write(pid):
+        if not authorize_write(pid, uid):
             raise PermissionError(
                 "Administrative authorization required"
             )
@@ -419,6 +453,10 @@ def handle_request(request, pid):
     )
 
 
+# ============================================================
+# Client handling
+# ============================================================
+
 def handle_client(connection):
     try:
         pid, uid, gid = get_peer_credentials(
@@ -456,6 +494,7 @@ def handle_client(connection):
             result = handle_request(
                 request,
                 pid,
+                uid,
             )
 
             response = {
@@ -470,6 +509,13 @@ def handle_client(connection):
                 "error_type": "authorization",
             }
 
+        except sqlite3.IntegrityError as exc:
+            response = {
+                "ok": False,
+                "error": str(exc),
+                "error_type": "database",
+            }
+
         except Exception as exc:
             response = {
                 "ok": False,
@@ -500,6 +546,10 @@ def handle_client(connection):
         connection.close()
 
 
+# ============================================================
+# IPC server
+# ============================================================
+
 class IPCServer:
 
     def __init__(
@@ -515,7 +565,10 @@ class IPCServer:
         self._stop_event = threading.Event()
 
     def start(self):
-        if self._thread is not None:
+        if (
+            self._thread is not None
+            and self._thread.is_alive()
+        ):
             return
 
         self.socket_path.parent.mkdir(
@@ -564,7 +617,9 @@ class IPCServer:
                 pass
 
         if self._thread is not None:
-            self._thread.join(timeout=2)
+            self._thread.join(
+                timeout=2
+            )
 
         self._thread = None
         self.server_socket = None