Island: Raise FileRetrievalError in DirectoryFileStorageService

monkey/monkey_island/cc/resources/pba_file_download.py

@@ -3,7 +3,7 @@ import logging
 import flask_restful
 from flask import make_response, send_file
 
-from monkey_island.cc.services import IFileStorageService
+from monkey_island.cc.services import FileRetrievalError, IFileStorageService
 
 logger = logging.getLogger(__file__)
 
@@ -23,7 +23,7 @@ class PBAFileDownload(flask_restful.Resource):
 
             # `send_file()` handles the closing of the open file.
             return send_file(file, mimetype="application/octet-stream")
-        except OSError as ex:
-            error_msg = f"Failed to open file {filename}: {ex}"
+        except FileRetrievalError as err:
+            error_msg = f"Failed to open file {filename}: {err}"
             logger.error(error_msg)
             return make_response({"error": error_msg}, 404)

monkey/monkey_island/cc/resources/pba_file_upload.py

@@ -9,7 +9,7 @@ from werkzeug.utils import secure_filename
 
 from common.config_value_paths import PBA_LINUX_FILENAME_PATH, PBA_WINDOWS_FILENAME_PATH
 from monkey_island.cc.resources.auth.auth import jwt_required
-from monkey_island.cc.services import IFileStorageService
+from monkey_island.cc.services import FileRetrievalError, IFileStorageService
 from monkey_island.cc.services.config import ConfigService
 
 logger = logging.getLogger(__file__)
@@ -53,8 +53,8 @@ class FileUpload(flask_restful.Resource):
 
             # `send_file()` handles the closing of the open file.
             return send_file(file, mimetype="application/octet-stream")
-        except OSError as ex:
-            error_msg = f"Failed to open file {filename}: {ex}"
+        except FileRetrievalError as err:
+            error_msg = f"Failed to open file {filename}: {err}"
             logger.error(error_msg)
             return make_response({"error": error_msg}, 404)
 

monkey/monkey_island/cc/services/__init__.py

@@ -1,4 +1,4 @@
-from .i_file_storage_service import IFileStorageService
+from .i_file_storage_service import IFileStorageService, FileRetrievalError
 from .directory_file_storage_service import DirectoryFileStorageService
 
 from .authentication.authentication_service import AuthenticationService

monkey/monkey_island/cc/services/directory_file_storage_service.py

@@ -5,7 +5,7 @@ from typing import BinaryIO
 from common.utils.file_utils import get_all_regular_files_in_directory
 from monkey_island.cc.server_utils.file_utils import create_secure_directory
 
-from . import IFileStorageService
+from . import FileRetrievalError, IFileStorageService
 
 
 class DirectoryFileStorageService(IFileStorageService):
@@ -35,7 +35,11 @@ class DirectoryFileStorageService(IFileStorageService):
 
     def open_file(self, unsafe_file_name: str) -> BinaryIO:
         safe_file_path = self._get_safe_file_path(unsafe_file_name)
-        return open(safe_file_path, "rb")
+
+        try:
+            return open(safe_file_path, "rb")
+        except OSError as err:
+            raise FileRetrievalError(f"Failed to retrieve file {safe_file_path}: {err}") from err
 
     def delete_file(self, unsafe_file_name: str):
         safe_file_path = self._get_safe_file_path(unsafe_file_name)

monkey/monkey_island/cc/services/i_file_storage_service.py

@@ -2,6 +2,10 @@ import abc
 from typing import BinaryIO
 
 
+class FileRetrievalError(ValueError):
+    pass
+
+
 class IFileStorageService(metaclass=abc.ABCMeta):
     """
     A service that allows the storage and retrieval of individual files.
@@ -25,6 +29,7 @@ class IFileStorageService(metaclass=abc.ABCMeta):
         :param unsafe_file_name: An unsanitized file name that identifies the file to be opened
         :return: A file-like object providing access to the file's contents
         :rtype: io.BinaryIO
+        :raises FileRetrievalError: if the file cannot be opened
         """
         pass
 

monkey/tests/unit_tests/monkey_island/cc/resources/test_pba_file_download.py

@@ -4,7 +4,7 @@ from typing import BinaryIO
 import pytest
 
 from common import DIContainer
-from monkey_island.cc.services import IFileStorageService
+from monkey_island.cc.services import FileRetrievalError, IFileStorageService
 
 FILE_NAME = "test_file"
 FILE_CONTENTS = b"HelloWorld!"
@@ -19,7 +19,7 @@ class MockFileStorageService(IFileStorageService):
 
     def open_file(self, unsafe_file_name: str) -> BinaryIO:
         if unsafe_file_name != FILE_NAME:
-            raise OSError()
+            raise FileRetrievalError()
 
         return self._file
 

monkey/tests/unit_tests/monkey_island/cc/resources/test_pba_file_upload.py

@@ -6,7 +6,7 @@ from tests.utils import raise_
 
 from common import DIContainer
 from monkey_island.cc.resources.pba_file_upload import LINUX_PBA_TYPE, WINDOWS_PBA_TYPE
-from monkey_island.cc.services import IFileStorageService
+from monkey_island.cc.services import FileRetrievalError, IFileStorageService
 
 TEST_FILE_CONTENTS = b"m0nk3y"
 TEST_FILE = (
@@ -48,8 +48,7 @@ class MockFileStorageService(IFileStorageService):
 
     def open_file(self, unsafe_file_name: str) -> BinaryIO:
         if self._file is None:
-            # TODO: Add FileRetrievalError
-            raise OSError()
+            raise FileRetrievalError()
         return self._file
 
     def delete_file(self, unsafe_file_name: str):

monkey/tests/unit_tests/monkey_island/cc/services/test_directory_file_storage_service.py

@@ -5,10 +5,10 @@ import pytest
 from tests.monkey_island.utils import assert_linux_permissions, assert_windows_permissions
 
 from monkey_island.cc.server_utils.file_utils import is_windows_os
-from monkey_island.cc.services import DirectoryFileStorageService
+from monkey_island.cc.services import DirectoryFileStorageService, FileRetrievalError
 
 
-def test_error_if_file(tmp_path):
+def test_error_if_storage_directory_is_file(tmp_path):
     new_file = tmp_path / "new_file.txt"
     new_file.write_text("HelloWorld!")
 
@@ -126,3 +126,10 @@ def test_remove_nonexistant_file(tmp_path):
 
     # This test will fail if this call raises an exception.
     fss.delete_file("nonexistant_file.txt")
+
+
+def test_open_nonexistant_file(tmp_path):
+    fss = DirectoryFileStorageService(tmp_path)
+
+    with pytest.raises(FileRetrievalError):
+        fss.open_file("nonexistant_file.txt")