fix: always use codejail.safe_exec.safe_exec when executing code (#26)

Usage of unsafely is determined by the setting
`COURSES_WITH_UNSAFE_CODE` in the edx-platform code, when True, the
jailed code would skip the sandboxed environment and run directly on the
service environment.

Allowing the use of unsafely through an HTTP call is an unnecesary
attack vector.

Author: MoisesGSalas

codejailservice/routes/code_exec_service.py

@@ -28,7 +28,7 @@ def code_exec():
     # Lazy imports of codejail functions according(after) the configuration  app.
     (
         safe_exec_exception,
-        codejail_not_safe_exec,
+        _,
         codejail_safe_exec,
     ) = import_code_jail_safe_exec()
 
@@ -37,9 +37,7 @@ def code_exec():
 
     unsafely = payload["unsafely"]
     if unsafely:
-        exec_fn = codejail_not_safe_exec
-    else:
-        exec_fn = codejail_safe_exec
+        log.warning("Ignoring execution with unsafely=true")
 
     try:
         python_path = payload["python_path"]
@@ -55,7 +53,7 @@ def code_exec():
             course_id,
         )
         start = timeit.default_timer()
-        exec_fn(
+        codejail_safe_exec(
             payload["code"],
             globals_dict,
             python_path=python_path,

codejailservice/tests/test_code_exec_service.py

@@ -103,15 +103,15 @@ def test_unsafe_code_exec_success(self, import_code_jail_safe_exec):
 
         self.assertEqual(200, response.status_code)
         self.assertDictEqual(expected_result, response.json)
-        unsafe_exec.assert_called_once_with(
+        safe_exec.assert_called_once_with(
             payload["code"],
             payload["globals_dict"],
             python_path=payload["python_path"],
             extra_files=[],
             limit_overrides_context=payload["limit_overrides_context"],
             slug=payload["slug"],
         )
-        safe_exec.assert_not_called()
+        unsafe_exec.assert_not_called()
 
     @mock.patch("codejailservice.routes.code_exec_service.import_code_jail_safe_exec")
     def test_unsafe_code_exec_failure(self, import_code_jail_safe_exec):
@@ -128,7 +128,7 @@ def test_unsafe_code_exec_failure(self, import_code_jail_safe_exec):
             unsafe_exec,
             safe_exec,
         )
-        unsafe_exec.side_effect = Exception("SyntaxError: invalid syntax ' with status code: 1")
+        safe_exec.side_effect = Exception("SyntaxError: invalid syntax ' with status code: 1")
         payload = {
             "code": "Syntax error",
             "globals_dict": {"seed": 1, "anonymous_student_id": "student"},
@@ -152,6 +152,7 @@ def test_unsafe_code_exec_failure(self, import_code_jail_safe_exec):
         self.assertEqual(200, response.status_code)
         self.assertEqual(expected_result['emsg'], response.json["emsg"])
         self.assertEqual(expected_result['globals_dict'], response.json["globals_dict"])
+        unsafe_exec.assert_not_called()
 
     @mock.patch("codejailservice.routes.code_exec_service.import_code_jail_safe_exec")
     def test_safe_code_exec_failure(self, import_code_jail_safe_exec):
@@ -192,3 +193,4 @@ def test_safe_code_exec_failure(self, import_code_jail_safe_exec):
         self.assertEqual(200, response.status_code)
         self.assertEqual(expected_result['emsg'], response.json["emsg"])
         self.assertEqual(expected_result['globals_dict'], response.json["globals_dict"])
+        unsafe_exec.assert_not_called()