File Manager

#!/bin/sh
# It receives as arguments:
# - $1 polydir path (see WARNING below)
# - $2 instance path (see WARNING below)
# - $3 flag whether the instance dir was newly created (0 - no, 1 - yes)
# - $4 user name
# - $5 flag whether the polydir path ($1) is safe (0 - unsafe, 1 -safe)
# - $6 flag whether the instance path ($2) is safe (0 - unsafe, 1 - safe)
#
# WARNING: This script is invoked with full root privileges. Accessing
# the polydir ($1) and the instance ($2) directories in this context may be
# extremely dangerous as those can be under user control. The flags $5 and $6
# are provided to let you know if all the segments part of the path (except the
# last one) are owned by root and are writable by root only. If the path does
# not meet these criteria, you expose yourself to possible symlink attacks when
# accessing these path.
# However, even if the path components are safe, the content of the
# directories may still be owned/writable by a user, so care must be taken!
#
# The following section will copy the contents of /etc/skel if this is a
# newly created home directory.

# Executes only if the polydir path is safe
if [ "$5" = 1 ]; then

    if [ "$3" = 1 ]; then
            # This line will fix the labeling on all newly created directories
            [ -x /sbin/restorecon ] && /sbin/restorecon "$1"
            user="$4"
            passwd=$(getent passwd "$user")
            homedir=$(echo "$passwd" | cut -f6 -d":")
            if [ "$1" = "$homedir" ]; then
                    gid=$(echo "$passwd" | cut -f4 -d":")
                    cp -rT /etc/skel "$homedir"
                    chown -R "$user":"$gid" "$homedir"
                    mask=$(sed -E -n 's/^UMASK[[:space:]]+([^#[:space:]]+).*/\1/p' /etc/login.defs)
                    mode=$(printf "%o" $((0777 & ~mask)))
                    chmod ${mode:-700} "$homedir"
                    [ -x /sbin/restorecon ] && /sbin/restorecon -R "$homedir"
            fi
    fi
fi
exit 0