rootshell: use seteuid/setegid instead

This is also what sshell does.

rootshell/src/main.rs

@@ -1,5 +1,3 @@
-#![feature(setgroups)]
-
 //! a simple shell for uploading to the orbic device.
 //! 
 //! It literally just runs bash as UID/GID 0 
@@ -7,23 +5,19 @@ use std::process::Command;
 use std::os::unix::process::CommandExt;
 use std::env;
 
-const ANDROID_PARANOID_NETWORK_GROUPS: &[u32] = &[
-   3001, // AID_BT
-   3002, // AID_BT_NET
-   3003, // AID_INET
-   3004, // AID_NET_RAW
-   3005, // AID_ADMIN
-];
+use nix::unistd::{Gid, Uid};
 
 fn main() {
    let mut args = env::args();
 
+   nix::unistd::setegid(Gid::from_raw(0)).expect("setegid(0) failed");
+   nix::unistd::seteuid(Uid::from_raw(0)).expect("seteuid(0) failed");
+
    // discard argv[0]
    let _ = args.next();
    Command::new("/bin/bash")
 	.args(args)
 	.uid(0)
 	.gid(0)
-   .groups(ANDROID_PARANOID_NETWORK_GROUPS)
 	.exec();
 }