database.rules.json

{
  "rules": {
    "rooms": {
      ".read": false,
      ".write": "auth != null",
      "$roomId": {
        ".read": true,
        ".write": "auth != null && (!data.exists() || data.child('authorId').val() == auth.id)",
        "questions": {
          ".read": true,
          ".write": "auth != null && (!data.exists() || data.parent().child('authorId').val() == auth.id)",
          "likes": {
            ".read": true,
            ".write": "auth != null && (!data.exists() || data.child('authorId').val() == auth.id)"  
          }
        }
      }
    }
  }
}