rust caused by salt solution & stainless steel
Chloride will pit/rust 304 ,not quite as much rust/pits on 316/317. Many things make it worse such as limited air access ( under deposit or crevice corrosion ).Oxygen can help rebuild the passive film. For your long term exposure ceramics and glass containers is the best fix. For metal containers ,much higher alloy is needed such as Incoloy 825.