Download the root file kernel For root the Galaxy S8 Plus SM-G955F
Model Number : SM-G955F
Android Version : Nougat & Oreo (7.0 & 8.0)
Extract the kernel placed in this post after download and Flash the file in the pda section in the odin software.
This file is only for Galaxy S8 Plus SM-G955F model, dont use this file for other models .if use it can damaged your device