Fix: correctly serve app logo specified in env (#13561)

src/documents/tests/test_api_app_config.py

@@ -12,6 +12,7 @@ from rest_framework import status
 from rest_framework.test import APITestCase
 
 from documents.tests.utils import DirectoriesMixin
+from documents.tests.utils import read_streaming_response
 from paperless.models import ApplicationConfiguration
 from paperless.models import ColorConvertChoices
 
@@ -193,6 +194,7 @@ class TestApiAppConfig(DirectoriesMixin, APITestCase):
         response = self.client.get("/logo/simple.jpg")
         self.assertEqual(response.status_code, status.HTTP_200_OK)
         self.assertIn("image/jpeg", response["Content-Type"])
+        response.close()
 
         config = ApplicationConfiguration.objects.first()
         assert config is not None
@@ -212,6 +214,46 @@ class TestApiAppConfig(DirectoriesMixin, APITestCase):
         )
         self.assertFalse(Path(old_logo.path).exists())
 
+    @override_settings(APP_LOGO="/logo/simple.jpg")
+    def test_serve_app_logo_from_environment_setting(self) -> None:
+        """
+        GIVEN:
+            - No uploaded app logo
+            - PAPERLESS_APP_LOGO points to a file in the media logo directory
+        WHEN:
+            - The configured logo URL is requested
+        THEN:
+            - The environment-configured logo is served
+        """
+        logo = self.dirs.media_dir / "logo" / "simple.jpg"
+        logo.parent.mkdir()
+        expected_content = (
+            Path(__file__).parent / "samples" / "simple.jpg"
+        ).read_bytes()
+        logo.write_bytes(expected_content)
+
+        response = self.client.get("/logo/simple.jpg")
+
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertIn("image/jpeg", response["Content-Type"])
+        self.assertEqual(read_streaming_response(response), expected_content)
+
+    @override_settings(APP_LOGO="/logo/../outside-logo.jpg")
+    def test_environment_app_logo_must_be_inside_logo_directory(self) -> None:
+        """
+        GIVEN:
+            - PAPERLESS_APP_LOGO resolves outside the media logo directory
+        WHEN:
+            - The configured logo URL is requested
+        THEN:
+            - The file is not served
+        """
+        (self.dirs.media_dir / "outside-logo.jpg").write_bytes(b"not a logo")
+
+        response = self.client.get("/logo/outside-logo.jpg")
+
+        self.assertEqual(response.status_code, status.HTTP_404_NOT_FOUND)
+
     def test_api_strips_exif_data_from_uploaded_logo(self) -> None:
         """
         GIVEN:

src/documents/views.py

@@ -5348,15 +5348,26 @@ def serve_logo(request: HttpRequest, filename: str | None = None) -> FileRespons
     config = ApplicationConfiguration.objects.first()
     app_logo = config.app_logo
 
-    if not app_logo:
-        raise Http404("No logo configured")
+    if app_logo:
+        path = Path(app_logo.path)
+        logo_name = app_logo.name
+    else:
+        if not settings.APP_LOGO:
+            raise Http404("No logo configured")
+
+        logo_root = (Path(settings.MEDIA_ROOT) / "logo").resolve()
+        path = (Path(settings.MEDIA_ROOT) / settings.APP_LOGO.lstrip("/")).resolve()
+        if not path.is_relative_to(logo_root) or not path.is_file():
+            raise Http404("Configured logo not found")
+
+        logo_name = path.name
 
-    path = app_logo.path
     content_type = magic.from_file(path, mime=True) or "application/octet-stream"
+    logo_file = app_logo.open("rb") if app_logo else path.open("rb")
 
     return FileResponse(
-        app_logo.open("rb"),
+        logo_file,
         content_type=content_type,
-        filename=app_logo.name,
+        filename=logo_name,
         as_attachment=True,
     )