change mirror

copying home to overlayfs might not be a good idea

menhera.sh

@@ -3,25 +3,69 @@ set -Eeuo pipefail
 # disable command path hashing as we are going to move fast and break things
 set +h
 
+# config
 WORKDIR="/tmp/menhera"
-MIRROR="https://iso.meson.cc/ultralite/archlinux"
+MIRROR="https://iso-ultralite.meson.cc/archlinux"
 ROOTFS="${MIRROR}/iso/latest/arch/x86_64/airootfs.sfs"
 
+declare -A ARCH_MAP=(
+    ["x86_64"]="amd64"
+)
+
 # internal global variables
 OLDROOT="/"
 NEWROOT=""
 
-[[ "$(uname -m)" == "x86_64" ]] || { echo "error: wrong arch $(uname -m) (not x86_64)"; exit 1; }
+MACHINE_TYPE=$(uname -m)
+ARCH_ID=${ARCH_MAP[$MACHINE_TYPE]:-$MACHINE_TYPE}
 
-PUBKEY="./key.pub"
+# fix possible PATH pMYMAP[missing]+_roblems
-[ -f "$PUBKEY" ] || { echo "error: you should put your ssh public key at ${PUBKEY} in order to ssh with root account and this key later"; exit 1; }
+export PATH="$PATH:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
 
-if [[ $EUID -ne 0 ]]; then
+menhera::reset_sshd_config() {
-    echo "This script must be run as root"
+    cat > /etc/ssh/sshd_config <<EOF
+PermitRootLogin yes
+AcceptEnv LANG LC_*
+EOF
+}
+
+# environment compatibility
+menhera::__compat_restart_ssh() {
+    if [ -x "$(command -v systemctl)" ]; then
+        systemctl daemon-reload
+        if ! systemctl restart sshd; then
+            echo "SSH daemon start failed, try resetting config..."
+            menhera::reset_sshd_config
+            if ! systemctl restart sshd; then
+                echo "SSH daemon fail to start, dropping you to a shell..."
+                sh
+            fi
+        fi
+    elif false && [ -x "$(command -v service)" ]; then # there is no such thing in archlinux
+        if ! service ssh restart; then
+            echo "SSH daemon start failed, try resetting config..."
+            menhera::reset_sshd_config
+            if ! service ssh restart; then
+                echo "SSH daemon fail to start, dropping you to a shell..."
+                sh
+            fi
+        fi
+    else
+        echo "ERROR: Cannot restart SSH server, init system not recoginzed" >&2
         exit 1
-fi
+    fi
+}
 
-systemctl status > /dev/null || { echo "error: no systemd"; exit 1; }
+menhera::__compat_reload_init() {
+    if [ -x "$(command -v systemctl)" ]; then
+        systemctl daemon-reexec
+    elif [ -x "$(command -v telinit)" ]; then
+        telinit u
+    else
+        echo "ERROR: Cannot re-exec init, init system not recoginzed" >&2
+        exit 1
+    fi
+}
 
 # helper functions
 # https://stackoverflow.com/a/3232082/2646069
@@ -38,6 +82,160 @@ menhera::confirm() {
     esac
 }
 
+# jobs
+menhera::get_rootfs() {
+    if [ -z "${ROOTFS}" ]; then
+        echo "Getting rootfs URL..."
+
+        # forgive me for parsing HTML with these shit
+        # and hope it works
+        ROOTFS_TIME=$(wget -qO- --show-progress "https://images.linuxcontainers.org/images/debian/buster/${ARCH_ID}/default/?C=M;O=D" | grep -oP '(\d{8}_\d{2}:\d{2})' | head -n 1)
+
+        ROOTFS="https://images.linuxcontainers.org/images/debian/buster/${ARCH_ID}/default/${ROOTFS_TIME}/rootfs.squashfs"
+    else
+        echo "\$ROOTFS is set to '$ROOTFS'"
+    fi
+}
+
+menhera::sync_filesystem() {
+    echo "Syncing..."
+    sync
+    sync
+}
+
+menhera::prepare_environment() {
+    echo "Loading kernel modules..."
+    modprobe overlay
+    modprobe squashfs
+
+    sysctl kernel.panic=10
+
+    echo "Creating workspace in '${WORKDIR}'..."
+    # workspace
+    mkdir -p "${WORKDIR}"
+    mount -t tmpfs -o size=100% tmpfs "${WORKDIR}"
+
+    # new rootfs
+    mkdir -p "${WORKDIR}/newroot"
+    # readonly part of new rootfs
+    mkdir -p "${WORKDIR}/newrootro"
+    # writeable part of new rootfs
+    mkdir -p "${WORKDIR}/newrootrw"
+    # overlayfs workdir
+    mkdir -p "${WORKDIR}/overlayfs_workdir"
+
+    echo "Downloading temporary rootfs..."
+    wget -q --show-progress -O "${WORKDIR}/rootfs.squashfs" "${ROOTFS}"
+}
+
+menhera::mount_new_rootfs() {
+    echo "Mounting temporary rootfs..."
+    mount -t squashfs "${WORKDIR}/rootfs.squashfs" "${WORKDIR}/newrootro"
+    mount -t overlay overlay -o rw,lowerdir="${WORKDIR}/newrootro",upperdir="${WORKDIR}/newrootrw",workdir="${WORKDIR}/overlayfs_workdir" "${WORKDIR}/newroot"
+
+    NEWROOT="${WORKDIR}/newroot"
+}
+
+menhera::install_software() {
+    return
+    echo "Installing OpenSSH Server into new rootfs..."
+
+    # disable APT cache
+    echo -e 'Dir::Cache "";\nDir::Cache::archives "";' > "${NEWROOT}/etc/apt/apt.conf.d/00_disable-cache-directories"
+
+    DEBIAN_FRONTEND=noninteractive chroot "${NEWROOT}" apt-get update -y
+    DEBIAN_FRONTEND=noninteractive chroot "${NEWROOT}" apt-get -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" install -y openssh-server
+}
+
+menhera::copy_config() {
+    echo "Copying important config into new rootfs..."
+    ! cp -axL "${OLDROOT}/etc/resolv.conf" "${NEWROOT}/etc"
+    ! cp -axr "${OLDROOT}/etc/ssh" "${NEWROOT}/etc"
+    ! cp -ax "${OLDROOT}/etc/"{passwd,shadow} "${NEWROOT}/etc"
+    ! cp -axr "${OLDROOT}/root/.ssh" "${NEWROOT}/root"
+
+    chroot "${NEWROOT}" chsh -s /bin/bash root
+
+    cat > "${NEWROOT}/etc/motd" <<EOF
+
+Download menhera.sh at https://github.com/Jamesits/menhera.sh
+
+!!!NOTICE!!!
+
+This is a minimal RAM system created by menhera.sh. Feel free to format your disk, but don't blame anyone
+except yourself if you lost important files or your system is broken.
+
+If you think you've done something wrong, reboot immediately -- there is still hope.
+
+Your original rootfs is at /mnt/oldroot. Be careful dealing with it.
+
+Have a lot of fun...
+EOF
+}
+
+menhera::swap_root() {
+    echo "Swapping rootfs..."
+    # prepare future mount point for our old rootfs
+    mkdir -p "${WORKDIR}/newroot/mnt/oldroot"
+    mount --make-rprivate /
+
+    # swap root
+    pivot_root "${WORKDIR}/newroot" "${WORKDIR}/newroot/mnt/oldroot"
+
+    OLDROOT="/mnt/oldroot"
+    NEWROOT="/"
+
+    # move mounts
+    for i in dev proc sys run; do
+        if [ -d "${OLDROOT}/$i" ]; then
+            mount --move "${OLDROOT}/$i" "${NEWROOT}/$i"
+        fi
+    done
+    mount -t tmpfs -o size=100% tmpfs "${NEWROOT}/tmp"
+
+    mkdir -p "${WORKDIR}"
+    mount --move "${OLDROOT}/${WORKDIR}" "${WORKDIR}"
+
+    echo "Restarting SSH daemon..."
+    menhera::__compat_restart_ssh
+}
+
+menhera::clear_processes() {
+    echo "Disabling swap..."
+    swapoff -a
+
+    echo "Restarting init process..."
+    menhera::__compat_reload_init
+    # hope 15s is enough
+    sleep 15
+
+    echo "Killing all programs still using the old root..."
+    fuser -kvm "${OLDROOT}" -15
+    # in most cases the parent process of this script will be killed, so goodbye
+}
+
+# main procedure
+LIBRARY_ONLY=0
+
+while test $# -gt 0
+do
+    case "$1" in
+        --lib) LIBRARY_ONLY=1
+            ;;
+    esac
+    shift
+done
+
+if [[ $LIBRARY_ONLY -eq 1 ]]; then
+    # acting as a library only
+    return 0
+fi
+
+if [[ $EUID -ne 0 ]]; then
+    echo "This script must be run as root" 
+    exit 1
+fi
+
 echo -e "We will start a temporary RAM system as your recovery environment."
 echo -e "Note that this script will kill programs and umount filesystems without prompting."
 echo -e "Please confirm:"
@@ -45,82 +243,23 @@ echo -e "\tYou have closed all programs you can, and backed up all important dat
 echo -e "\tYou can SSH into your system as root user"
 menhera::confirm || exit -1
 
-# fix possible PATH problems
+menhera::get_rootfs
-export PATH="$PATH:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+menhera::sync_filesystem
 
-echo "Loading kernel modules..."
+menhera::prepare_environment
-modprobe overlay
+menhera::mount_new_rootfs
-modprobe squashfs
+menhera::copy_config
-sysctl kernel.panic=10
+menhera::install_software
-
+menhera::swap_root
-echo "Creating workspace in '${WORKDIR}'..."
-# workspace
-mkdir -p "${WORKDIR}"
-mount -t tmpfs -o size=100% tmpfs "${WORKDIR}"
-
-mkdir -p "${WORKDIR}/newroot" # where iso is stored
-mkdir -p "${WORKDIR}/newrootro" # lower
-mkdir -p "${WORKDIR}/newrootrw" # upper
-mkdir -p "${WORKDIR}/overlayfs_workdir" # work
-
-echo "Downloading temporary rootfs..."
-wget -O "${WORKDIR}/rootfs.squashfs" "${ROOTFS}"
-
-echo "Mounting temporary rootfs..."
-mount -t squashfs "${WORKDIR}/rootfs.squashfs" "${WORKDIR}/newrootro"
-mount -t overlay overlay -o rw,lowerdir="${WORKDIR}/newrootro",upperdir="${WORKDIR}/newrootrw",workdir="${WORKDIR}/overlayfs_workdir" "${WORKDIR}/newroot"
-NEWROOT="${WORKDIR}/newroot"
-
-rm -f "${NEWROOT}/etc/resolv.conf"
-cat "${OLDROOT}/etc/resolv.conf" > "${NEWROOT}/etc/resolv.conf"
-install -DTm0600 <(cat "$PUBKEY") "${NEWROOT}/root/.ssh/authorized_keys"
-chmod 0700 "${NEWROOT}/root/.ssh"
-sync && sync # why sync twice? idk
-
-echo "Swapping rootfs..."
-# prepare future mount point for our old rootfs
-mkdir -p "${WORKDIR}/newroot/mnt/oldroot"
-mount --make-rprivate /
-
-# swap root
-pivot_root "${WORKDIR}/newroot" "${WORKDIR}/newroot/mnt/oldroot"
-
-OLDROOT="/mnt/oldroot"
-NEWROOT="/"
-
-# move mounts
-for i in dev proc sys run; do
-    if [ -d "${OLDROOT}/$i" ]; then
-        mount --move "${OLDROOT}/$i" "${NEWROOT}/$i"
-    fi
-done
-mount -t tmpfs -o size=100% tmpfs "${NEWROOT}/tmp"
-
-mkdir -p "${WORKDIR}"
-mount --move "${OLDROOT}/${WORKDIR}" "${WORKDIR}"
-
-echo "Restarting SSH daemon..."
-systemctl daemon-reload
-systemctl is-active ssh && systemctl stop ssh || true
-systemctl restart sshd
-
-echo "Disabling swap..."
-swapoff -a
-
-echo "Restarting init process..."
-systemctl daemon-reexec
-
-systemctl --quiet is-system-running || true
 
 echo -e "If you are connecting from SSH, please create a second session to this host use root and"
 echo -e "confirm you can get a shell."
 echo -e "After your confirmation, we are going to kill the old SSH server."
 
 if menhera::confirm; then 
-    echo "Killing all programs still using the old root..."
+    menhera::clear_processes
-    fuser -kvm "${OLDROOT}" -15
-    # in most cases the parent process of this script will be killed, so goodbye
 else
     echo -e "Please manually issue a reboot to recover your old OS. If you believe there is a bug in menhera.sh, "
     echo -e "raise a ticket at https://github.com/Jamesits/menhera.sh/issues ."
+    exit 1
 fi