Disable extension loading once --load-extension extensions are loaded

Refs GHSA-2mvv-ffvc-q5p6

Co-authored-by: Alex Garcia <15178711+asg017@users.noreply.github.com>

tests/test_load_extensions.py

@@ -1,4 +1,5 @@
 from pathlib import Path
+from unittest import mock
 
 import pytest
 
@@ -20,6 +21,29 @@ def has_compiled_ext():
     return False
 
 
+@pytest.mark.parametrize("load_fails", (False, True))
+def test_load_extension_is_disabled(load_fails):
+    ds = Datasette(sqlite_extensions=[COMPILED_EXTENSION_PATH])
+    connection = mock.Mock()
+    if load_fails:
+        connection.load_extension.side_effect = RuntimeError
+
+    if load_fails:
+        with pytest.raises(RuntimeError):
+            ds._prepare_connection(connection, "data")
+    else:
+        ds._prepare_connection(connection, "data")
+
+    # Extensions are loaded using the Python API, never via SQL
+    assert connection.load_extension.mock_calls == [
+        mock.call(COMPILED_EXTENSION_PATH),
+    ]
+    assert connection.enable_load_extension.mock_calls == [
+        mock.call(True),
+        mock.call(False),
+    ]
+
+
 @pytest.mark.asyncio
 @pytest.mark.skipif(not has_compiled_ext(), reason="Requires compiled ext.c")
 async def test_load_extension_default_entrypoint():
@@ -64,3 +88,20 @@ async def test_load_extension_multiple_entrypoints():
     response = await ds.client.get("/_memory/-/query.json?_shape=arrays&sql=select+c()")
     assert response.status_code == 200
     assert response.json()["rows"][0][0] == "c"
+
+
+@pytest.mark.asyncio
+@pytest.mark.skipif(not has_compiled_ext(), reason="Requires compiled ext.c")
+async def test_sql_cannot_load_additional_extension():
+    ds = Datasette(sqlite_extensions=[COMPILED_EXTENSION_PATH])
+
+    response = await ds.client.get(
+        "/_memory/-/query.json",
+        params={
+            "sql": "select load_extension(:path, :entrypoint)",
+            "path": COMPILED_EXTENSION_PATH,
+            "entrypoint": "sqlite3_ext_b_init",
+        },
+    )
+    assert response.status_code == 400
+    assert response.json()["error"] == "not authorized"