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1 changed files with 80 additions and 217 deletions
297
menhera.sh
297
menhera.sh
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@ -3,68 +3,25 @@ set -Eeuo pipefail
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# disable command path hashing as we are going to move fast and break things
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set +h
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# config
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WORKDIR="/tmp/menhera"
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ROOTFS=""
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declare -A ARCH_MAP=(
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["x86_64"]="amd64"
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)
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MIRROR="https://iso.meson.cc/ultralite/archlinux"
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ROOTFS="${MIRROR}/iso/latest/arch/x86_64/airootfs.sfs"
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# internal global variables
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OLDROOT="/"
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NEWROOT=""
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MACHINE_TYPE=$(uname -m)
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ARCH_ID=${ARCH_MAP[$MACHINE_TYPE]:-$MACHINE_TYPE}
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[[ "$(uname -m)" == "x86_64" ]] || { echo "error: wrong arch $(uname -m) (not x86_64)"; exit 1; }
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# fix possible PATH pMYMAP[missing]+_roblems
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export PATH="$PATH:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
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PUBKEY="./key.pub"
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[ -f "$PUBKEY" ] || { echo "error: you should put your ssh public key at ${PUBKEY} in order to ssh with root account and this key later"; exit 1; }
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menhera::reset_sshd_config() {
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cat > /etc/ssh/sshd_config <<EOF
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PermitRootLogin yes
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AcceptEnv LANG LC_*
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EOF
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}
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if [[ $EUID -ne 0 ]]; then
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echo "This script must be run as root"
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exit 1
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fi
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# environment compatibility
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menhera::__compat_restart_ssh() {
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if [ -x "$(command -v systemctl)" ]; then
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systemctl daemon-reload
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if ! systemctl restart ssh; then
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echo "SSH daemon start failed, try resetting config..."
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menhera::reset_sshd_config
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if ! systemctl restart ssh; then
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echo "SSH daemon fail to start, dropping you to a shell..."
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sh
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fi
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fi
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elif [ -x "$(command -v service)" ]; then
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if ! service ssh restart; then
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echo "SSH daemon start failed, try resetting config..."
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menhera::reset_sshd_config
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if ! service ssh restart; then
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echo "SSH daemon fail to start, dropping you to a shell..."
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sh
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fi
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fi
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else
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echo "ERROR: Cannot restart SSH server, init system not recoginzed" >&2
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exit 1
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fi
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}
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menhera::__compat_reload_init() {
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if [ -x "$(command -v systemctl)" ]; then
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systemctl daemon-reexec
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elif [ -x "$(command -v telinit)" ]; then
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telinit u
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else
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echo "ERROR: Cannot re-exec init, init system not recoginzed" >&2
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exit 1
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fi
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}
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systemctl status > /dev/null || { echo "error: no systemd"; exit 1; }
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# helper functions
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# https://stackoverflow.com/a/3232082/2646069
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@ -72,7 +29,7 @@ menhera::confirm() {
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# call with a prompt string or use a default
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read -r -p "${1:-Are you sure? [y/N]} " response
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case "$response" in
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[yY][eE][sS]|[yY])
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[yY][eE][sS]|[yY])
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true
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;;
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*)
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@ -81,159 +38,6 @@ menhera::confirm() {
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esac
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}
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# jobs
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menhera::get_rootfs() {
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if [ -n ${ROOTFS} ]; then
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echo "Getting rootfs URL..."
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# forgive me for parsing HTML with these shit
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# and hope it works
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ROOTFS_TIME=$(wget -qO- --show-progress "https://images.linuxcontainers.org/images/debian/buster/${ARCH_ID}/default/?C=M;O=D" | grep -oP '(\d{8}_\d{2}:\d{2})' | head -n 1)
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ROOTFS="https://images.linuxcontainers.org/images/debian/buster/${ARCH_ID}/default/${ROOTFS_TIME}/rootfs.squashfs"
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else
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echo "\$ROOTFS is set to '$ROOTFS'"
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fi
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}
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menhera::sync_filesystem() {
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echo "Syncing..."
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sync
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sync
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}
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menhera::prepare_environment() {
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echo "Loading kernel modules..."
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modprobe overlay
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modprobe squashfs
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sysctl kernel.panic=10
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echo "Creating workspace in '${WORKDIR}'..."
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# workspace
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mkdir -p "${WORKDIR}"
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mount -t tmpfs -o size=100% tmpfs "${WORKDIR}"
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# new rootfs
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mkdir -p "${WORKDIR}/newroot"
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# readonly part of new rootfs
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mkdir -p "${WORKDIR}/newrootro"
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# writeable part of new rootfs
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mkdir -p "${WORKDIR}/newrootrw"
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# overlayfs workdir
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mkdir -p "${WORKDIR}/overlayfs_workdir"
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echo "Downloading temporary rootfs..."
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wget -q --show-progress -O "${WORKDIR}/rootfs.squashfs" "${ROOTFS}"
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}
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menhera::mount_new_rootfs() {
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echo "Mounting temporary rootfs..."
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mount -t squashfs "${WORKDIR}/rootfs.squashfs" "${WORKDIR}/newrootro"
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mount -t overlay overlay -o rw,lowerdir="${WORKDIR}/newrootro",upperdir="${WORKDIR}/newrootrw",workdir="${WORKDIR}/overlayfs_workdir" "${WORKDIR}/newroot"
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NEWROOT="${WORKDIR}/newroot"
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}
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menhera::install_software() {
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echo "Installing OpenSSH Server into new rootfs..."
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# disable APT cache
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echo -e 'Dir::Cache "";\nDir::Cache::archives "";' > "${NEWROOT}/etc/apt/apt.conf.d/00_disable-cache-directories"
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DEBIAN_FRONTEND=noninteractive chroot "${NEWROOT}" apt-get update -y
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DEBIAN_FRONTEND=noninteractive chroot "${NEWROOT}" apt-get -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" install -y openssh-server
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}
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menhera::copy_config() {
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echo "Copying important config into new rootfs..."
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! cp -axL "${OLDROOT}/etc/resolv.conf" "${NEWROOT}/etc"
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! cp -axr "${OLDROOT}/etc/ssh" "${NEWROOT}/etc"
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! cp -ax "${OLDROOT}/etc/"{passwd,shadow} "${NEWROOT}/etc"
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! cp -axr "${OLDROOT}/root/.ssh" "${NEWROOT}/root"
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chroot "${NEWROOT}" chsh -s /bin/bash root
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cat > "${NEWROOT}/etc/motd" <<EOF
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Download menhera.sh at https://github.com/Jamesits/menhera.sh
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!!!NOTICE!!!
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This is a minimal RAM system created by menhera.sh. Feel free to format your disk, but don't blame anyone
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except yourself if you lost important files or your system is broken.
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If you think you've done something wrong, reboot immediately -- there is still hope.
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Your original rootfs is at /mnt/oldroot. Be careful dealing with it.
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Have a lot of fun...
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EOF
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}
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menhera::swap_root() {
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echo "Swapping rootfs..."
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# prepare future mount point for our old rootfs
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mkdir -p "${WORKDIR}/newroot/mnt/oldroot"
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mount --make-rprivate /
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# swap root
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pivot_root "${WORKDIR}/newroot" "${WORKDIR}/newroot/mnt/oldroot"
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OLDROOT="/mnt/oldroot"
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NEWROOT="/"
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# move mounts
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for i in dev proc sys run; do
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if [ -d "${OLDROOT}/$i" ]; then
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mount --move "${OLDROOT}/$i" "${NEWROOT}/$i"
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fi
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done
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mount -t tmpfs -o size=100% tmpfs "${NEWROOT}/tmp"
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mkdir -p "${WORKDIR}"
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mount --move "${OLDROOT}/${WORKDIR}" "${WORKDIR}"
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echo "Restarting SSH daemon..."
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menhera::__compat_restart_ssh
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}
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menhera::clear_processes() {
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echo "Disabling swap..."
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swapoff -a
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echo "Restarting init process..."
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menhera::__compat_reload_init
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# hope 15s is enough
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sleep 15
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echo "Killing all programs still using the old root..."
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fuser -kvm "${OLDROOT}" -15
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# in most cases the parent process of this script will be killed, so goodbye
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}
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# main procedure
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LIBRARY_ONLY=0
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while test $# -gt 0
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do
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case "$1" in
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--lib) LIBRARY_ONLY=1
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;;
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esac
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shift
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done
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if [[ $LIBRARY_ONLY -eq 1 ]]; then
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# acting as a library only
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return 0
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fi
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if [[ $EUID -ne 0 ]]; then
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echo "This script must be run as root"
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exit 1
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fi
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echo -e "We will start a temporary RAM system as your recovery environment."
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echo -e "Note that this script will kill programs and umount filesystems without prompting."
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echo -e "Please confirm:"
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@ -241,23 +45,82 @@ echo -e "\tYou have closed all programs you can, and backed up all important dat
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echo -e "\tYou can SSH into your system as root user"
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menhera::confirm || exit -1
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menhera::get_rootfs
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menhera::sync_filesystem
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# fix possible PATH problems
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export PATH="$PATH:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
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menhera::prepare_environment
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menhera::mount_new_rootfs
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menhera::copy_config
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menhera::install_software
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menhera::swap_root
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echo "Loading kernel modules..."
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modprobe overlay
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modprobe squashfs
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sysctl kernel.panic=10
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echo "Creating workspace in '${WORKDIR}'..."
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# workspace
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mkdir -p "${WORKDIR}"
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mount -t tmpfs -o size=100% tmpfs "${WORKDIR}"
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mkdir -p "${WORKDIR}/newroot" # where iso is stored
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mkdir -p "${WORKDIR}/newrootro" # lower
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mkdir -p "${WORKDIR}/newrootrw" # upper
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mkdir -p "${WORKDIR}/overlayfs_workdir" # work
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echo "Downloading temporary rootfs..."
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wget -O "${WORKDIR}/rootfs.squashfs" "${ROOTFS}"
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echo "Mounting temporary rootfs..."
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mount -t squashfs "${WORKDIR}/rootfs.squashfs" "${WORKDIR}/newrootro"
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mount -t overlay overlay -o rw,lowerdir="${WORKDIR}/newrootro",upperdir="${WORKDIR}/newrootrw",workdir="${WORKDIR}/overlayfs_workdir" "${WORKDIR}/newroot"
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NEWROOT="${WORKDIR}/newroot"
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rm -f "${NEWROOT}/etc/resolv.conf"
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cat "${OLDROOT}/etc/resolv.conf" > "${NEWROOT}/etc/resolv.conf"
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install -DTm0600 <(cat "$PUBKEY") "${NEWROOT}/root/.ssh/authorized_keys"
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chmod 0700 "${NEWROOT}/root/.ssh"
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sync && sync # why sync twice? idk
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echo "Swapping rootfs..."
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# prepare future mount point for our old rootfs
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mkdir -p "${WORKDIR}/newroot/mnt/oldroot"
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mount --make-rprivate /
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# swap root
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pivot_root "${WORKDIR}/newroot" "${WORKDIR}/newroot/mnt/oldroot"
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OLDROOT="/mnt/oldroot"
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NEWROOT="/"
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# move mounts
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for i in dev proc sys run; do
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if [ -d "${OLDROOT}/$i" ]; then
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mount --move "${OLDROOT}/$i" "${NEWROOT}/$i"
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fi
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done
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mount -t tmpfs -o size=100% tmpfs "${NEWROOT}/tmp"
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mkdir -p "${WORKDIR}"
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mount --move "${OLDROOT}/${WORKDIR}" "${WORKDIR}"
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echo "Restarting SSH daemon..."
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systemctl daemon-reload
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systemctl is-active ssh && systemctl stop ssh || true
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systemctl restart sshd
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echo "Disabling swap..."
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swapoff -a
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echo "Restarting init process..."
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systemctl daemon-reexec
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systemctl --quiet is-system-running || true
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echo -e "If you are connecting from SSH, please create a second session to this host use root and"
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echo -e "confirm you can get a shell."
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echo -e "After your confirmation, we are going to kill the old SSH server."
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if menhera::confirm; then
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menhera::clear_processes
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if menhera::confirm; then
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echo "Killing all programs still using the old root..."
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fuser -kvm "${OLDROOT}" -15
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# in most cases the parent process of this script will be killed, so goodbye
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else
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echo -e "Please manually issue a reboot to recover your old OS. If you believe there is a bug in menhera.sh, "
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echo -e "raise a ticket at https://github.com/Jamesits/menhera.sh/issues ."
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exit 1
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fi
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