examples: Add a spawn gating example

Author: oleavr

examples/spawn_gating.py

@@ -0,0 +1,80 @@
+import threading
+
+from frida_tools.application import Reactor
+
+import frida
+
+
+class Application:
+    def __init__(self):
+        self._stop_requested = threading.Event()
+        self._reactor = Reactor(run_until_return=lambda reactor: self._stop_requested.wait())
+
+        self._device = frida.get_usb_device()
+        self._sessions = set()
+        self._sessions_lock = threading.Lock()
+
+        self._device.on("spawn-added", lambda spawn: self._reactor.schedule(lambda: self._on_spawn_added(spawn)))
+        self._device.on("spawn-removed", lambda spawn: self._reactor.schedule(lambda: self._on_spawn_removed(spawn)))
+
+    def run(self):
+        self._reactor.schedule(lambda: self._start())
+        self._reactor.run()
+
+    def _start(self):
+        self._device.enable_spawn_gating()
+
+    def _instrument(self, pid):
+        print(f"✔ attach(pid={pid})")
+        session = self._device.attach(pid)
+        session.on("detached", lambda reason: self._reactor.schedule(lambda: self._on_detached(pid, session, reason)))
+        print("✔ create_script()")
+        script = session.create_script(
+            """\
+const puts = new NativeFunction(Module.getGlobalExportByName('puts'), 'int', ['pointer']);
+puts(Memory.allocUtf8String('Hello from Frida agent'));
+Interceptor.attach(Module.getGlobalExportByName('open'), {
+  onEnter(args) {
+    send({
+      type: 'open',
+      path: args[0].readUtf8String()
+    });
+  }
+});
+"""
+        )
+        script.on("message", lambda message, data: self._reactor.schedule(lambda: self._on_message(pid, message)))
+        print("✔ load()")
+        script.load()
+        print(f"✔ resume(pid={pid})")
+        self._device.resume(pid)
+        with self._sessions_lock:
+            self._sessions.add(session)
+
+    def _on_spawn_added(self, spawn):
+        print(f"⚡ spawn_added: {spawn}")
+        t = threading.Thread(target=self._handle_spawn, args=(spawn,))
+        t.start()
+
+    def _handle_spawn(self, spawn):
+        if "/bin/ls" in spawn.identifier:
+            self._instrument(spawn.pid)
+        else:
+            pid = spawn.pid
+            print(f"✔ resume(pid={pid})")
+            self._device.resume(pid)
+
+    def _on_spawn_removed(self, spawn):
+        print(f"⚡ spawn_removed: {spawn}")
+
+    def _on_detached(self, pid, session, reason):
+        print(f"⚡ detached: pid={pid}, reason='{reason}'")
+        with self._sessions_lock:
+            self._sessions.remove(session)
+
+    def _on_message(self, pid, message):
+        print(f"⚡ message: pid={pid}, payload={message['payload']}")
+
+
+app = Application()
+app.run()