#!/bin/sh
#
# Copyright (c) 2006-2007, Gregory Fleischer (gfleischer@gmail.com)
# 
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#   
#   1. Redistributions of source code must retain the above copyright
#      notice, this list of conditions and the following disclaimer.
#   2. Redistributions in binary form must reproduce the above copyright
#      notice, this list of conditions and the following disclaimer in
#      the documentation and/or other materials provided with the
#      distribution.
#   3. The names of the authors may not be used to endorse or promote
#      products derived from this software without specific prior
#      written permission.
#   
# THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
#

set -e -u

if [ 0 != "$UID" ]; then
	echo "must run as root"
	exit 1
fi

if [ ! -f "runsh" ]; then
    echo "missing 'runsh' file"
    exit 1
fi

# add the lamp user
if ! egrep -q '^lamp:' /etc/passwd 2>/dev/null; then
        adduser lamp
fi

# where's the challenge?
DEST=/challenge

# create the directory
if [ -d $DEST ]; then rm -rfv $DEST; fi
mkdir -v $DEST
chmod -v 0500 $DEST
chown -v lamp:lamp $DEST

# build the chimney
mkfifo $DEST/chimney
chmod -v 666 $DEST/chimney 

# install nc
install -v -m0755 /bin/nc $DEST

# create a bin directory
BINDEST=$DEST-bin
if [ -d $BINDEST ]; then rm -rfv $BINDEST; fi
mkdir $BINDEST

ln -vs /usr/bin/id $BINDEST
ln -vs /bin/ls $BINDEST

# create the runlamp wrapper
cat >runlamp.c <<EOF
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

int
main(int argc, char **argv)
{

        char *cmd[] = {"/bin/bash", "-c", "/home/lamp/runsh", 0};
        execv(cmd[0], cmd);
        perror("execv failed");
        exit(-1);
}
EOF

gcc -Wall -s -o runlamp runlamp.c
install -v -m0755 runlamp /etc/smrsh/
chown -v lamp:lamp /etc/smrsh/runlamp

cat >/home/lamp/.forward <<EOF
\root, "|runlamp"
EOF

install -v -m0755 runsh /home/lamp

exit 0

# eof