path: root/debian/initramfs/hooks/cryptroot

#!/bin/sh

PREREQ=""

prereqs()
{
    echo "$PREREQ"
}

case "$1" in
    prereqs)
        prereqs
        exit 0
        ;;
esac

. /usr/share/initramfs-tools/hook-functions
. /lib/cryptsetup/functions
TABFILE="/etc/crypttab"


# device_uuid($device)
#   Print the UUID attribute of given block special $device.  Return 0
#   on success, 1 on error.
device_uuid() {
    local device="$1" uuid
    if uuid="$(blkid -s UUID -o value -- "$device")" && [ -n "$uuid" ]; then
        printf '%s\n' "$uuid"
    else
        return 1
    fi
}

# resolve_device({$device | $spec})
#   Take a path to (or spec for) a block special device, and set DEV to
#   the (symlink to block) device, and MAJ (resp. MIN) to its major-ID
#   (resp. minor ID) decimal value.  On error these variables are not
#   changed and 1 is returned.
resolve_device() {
    local spec="$1" dev devno maj min
    if dev="$(resolve_device_spec "$spec")" &&
            devno="$(stat -L -c"%t:%T" -- "$dev" 2>/dev/null)" &&
            maj="${devno%:*}" && min="${devno#*:}" &&
            [ "$devno" = "$maj:$min" ] && [ -n "$maj" ] && [ -n "$min" ] &&
            maj=$(( 0x$maj )) && min=$(( 0x$min )) && [ $maj -gt 0 ]; then
        DEV="$dev"
        MAJ="$maj"
        MIN="$min"
        return 0
    else
        cryptsetup_message "ERROR: Couldn't resolve device $spec"
    fi
    return 1
}

# get_mnt_devno($mountpoint)
#   Print the major:minor device ID(s) holding the file system currently
#   mounted currenty mounted on $mountpoint.
#   Return 0 on success, 1 on error (if $mountpoint is not a mountpoint).
get_mnt_devno() {
    local wantmount="$1" devnos="" uuid dev IFS
    local spec mountpoint fstype _ DEV MAJ MIN

    while IFS=" 	" read -r spec mountpoint fstype _; do
        # treat lines starting with '#' as comments; /proc/mounts
        # doesn't seem to contain these but per procfs(5) the format of
        # that file is analogous to fstab(5)'s
        if [ "${spec#\#}" = "$spec" ] && [ -n "$spec" ] &&
                [ "$(printf '%b' "$mountpoint")" = "$wantmount" ]; then
            # take the last mountpoint if used several times (shadowed)
            unset -v devnos
            spec="$(printf '%b' "$spec")"
            resolve_device "$spec" || continue # resolve_device() already warns on error
            fstype="$(printf '%b' "$fstype")"
            if [ "$fstype" = "btrfs" ]; then
                # btrfs can span over multiple devices
                if uuid="$(device_uuid "$DEV")"; then
                    for dev in "/sys/fs/$fstype/$uuid/devices"/*/dev; do
                        devnos="${devnos:+$devnos }$(cat "$dev")"
                    done
                else
                    cryptsetup_message "ERROR: $spec: Couldn't determine UUID"
                fi
            elif [ -n "$fstype" ]; then
                devnos="$MAJ:$MIN"
            fi
        fi
    done </proc/mounts

    if [ -z "${devnos:+x}" ]; then
        return 1 # not found
    else
        printf '%s' "$devnos"
    fi
}

# get_dmcrypt_slaves({/sys/dev/block/$maj:$min | /sys/devices/...})
#   Recursively print the crypttab(5) entries to FD nr. 3, for each
#   dm-crypt device holding $maj:$min (typically corresponding to an md,
#   lv, or dm-crypt device).  Slaves that aren't dm-crypt devices are
#   NOT printed.
get_dmcrypt_slaves() {
    local d="$1" devno maj min name slave
    [ -d "$d/slaves" ] || return 0
    if [ -d "$d/dm" ] && devno="$(cat "$d/dev")" &&
            maj="${devno%:*}" && min="${devno#*:}" &&
            [ "$devno" = "$maj:$min" ] && [ -n "$maj" ] && [ -n "$min" ] &&
            [ "$(dmsetup info -c --noheadings -o subsystem -j "$maj" -m "$min")" = "CRYPT" ] &&
            name="$(dmsetup info -c --noheadings -o unmangled_name -j "$maj" -m "$min")"; then
        # search for a crypttab entry with the given unmangled name
        crypttab_find_and_print_entry "$name"
    fi
    for slave in "$d/slaves"/*; do
        if [ -d "$slave" ] && slave="$(realpath -e -- "$slave")"; then
            get_dmcrypt_slaves "$slave"
        fi
    done
}

# crypttab_find_and_print_entry($target)
#   Find the crypttab(5) entry for the given (unmangled) $target and
#   print it - preserving the mangling - to FD nr. 3; but only if the
#   target has not already been processed during an earlier function
#   call.  (Processed target names are stored in
#   $DESTDIR/cryptroot/targets.)
#   Return 0 on success, 1 on error.
crypttab_find_and_print_entry() {
    local target="$1"
    local _CRYPTTAB_NAME _CRYPTTAB_SOURCE _CRYPTTAB_KEY _CRYPTTAB_OPTIONS
    if ! grep -Fxqz -e "$target" -- "$DESTDIR/cryptroot/targets"; then
        printf '%s\0' "$target" >>"$DESTDIR/cryptroot/targets"
        crypttab_find_entry "$target" || return 1
        crypttab_parse_options --missing-path=warn || return 1
        crypttab_print_entry
    fi
}

# crypttab_print_entry()
#   Print an unmangled crypttab(5) entry to FD nr. 3, using CRYPTTAB_*
#   and _CRYPTTAB_* values.
#   _CRYPTTAB_SOURCE is replaced with /dev/mapper/$sourcename for mapped
#   sources, otherwise by UUID=<uuid> if possible (eg, for LUKS).  If
#   the entry uses the 'decrypt_derived' keyscript, the other
#   crypttab(5) entries it depends on are (recursively) printed before
#   hand.
#   Various checks are performed on the key and crypttab options, but no
#   parsing is done so it's the responsibility of the caller to call
#   crypttab_parse_options().
#   Return 0 on success, 1 on error.
crypttab_print_entry() {
    local DEV MAJ MIN sourcename uuid keyfile
    if resolve_device "$CRYPTTAB_SOURCE"; then
        if [ "$(dmsetup info -c --noheadings -o devnos_used -- "$CRYPTTAB_NAME" 2>/dev/null)" != "$MAJ:$MIN" ]; then
            cryptsetup_message "ERROR: $CRYPTTAB_NAME: Source mismatch"
        elif sourcename="$(dmsetup info -c --noheadings -o mangled_name -j "$MAJ" -m "$MIN" 2>/dev/null)" &&
               [ -b "/dev/mapper/$sourcename" ]; then
            # for mapped sources, use the dm name as the lvm
            # local-block script doesn't work with UUIDs (#902943)
            _CRYPTTAB_SOURCE="/dev/mapper/$sourcename"
        elif uuid="$(device_uuid "$DEV")"; then
            # otherwise, use its UUID if possible (eg. for LUKS)
            _CRYPTTAB_SOURCE="UUID=$uuid"
        fi
        # on failure resolve_device() prints a warning and we try our
        # luck with the unchanged _CRYPTTAB_SOURCE value
    fi

    # if keyscript is set, the "key" is just an argument to the script
    if [ -z "${CRYPTTAB_OPTION_keyscript+x}" ] && [ "$CRYPTTAB_KEY" != "none" ]; then
        crypttab_key_check || return 1
        case "$CRYPTTAB_KEY" in
            $KEYFILE_PATTERN)
                mkdir -pm0700 -- "$DESTDIR/cryptroot/keyfiles"
                # $CRYPTTAB_NAME can't contain '/' (even after unmangling)
                keyfile="/cryptroot/keyfiles/$CRYPTTAB_NAME.key"
                if [ ! -f "$DESTDIR$keyfile" ] && ! copy_file keyfile "$CRYPTTAB_KEY" "$keyfile"; then
                    cryptsetup_message "WARNING: couldn't copy keyfile $CRYPTTAB_KEY"
                fi
                _CRYPTTAB_KEY="/cryptroot/keyfiles/$_CRYPTTAB_NAME.key" # preserve mangled name
                ;;
            *)
                if [ "$usage" = rootfs ]; then
                    cryptsetup_message "WARNING: Skipping root target $CRYPTTAB_NAME: uses a key file"
                    return 1
                elif [ "$usage" = resume ]; then
                    cryptsetup_message "WARNING: Resume target $CRYPTTAB_NAME uses a key file"
                fi
                if [ -L "$CRYPTTAB_KEY" ] && keyfile="$(readlink -- "$CRYPTTAB_KEY")" &&
                        [ "${keyfile#/}" != "$keyfile" ]; then
                    cryptsetup_message "WARNING: Skipping target $CRYPTTAB_NAME: key file is a symlink with absolute target"
                    return 1
                elif [ -f "$CRYPTTAB_KEY" ] && [ "$(stat -L -c"%m" -- "$CRYPTTAB_KEY" 2>/dev/null)" != "/" ]; then
                    cryptsetup_message "WARNING: Skipping target $CRYPTTAB_NAME: key file is not on the root FS"
                    return 1
                fi
                if [ ! -e "$CRYPTTAB_KEY" ]; then
                    cryptsetup_message "WARNING: Target $CRYPTTAB_NAME has a non-existing key file $CRYPTTAB_KEY"
                else
                    _CRYPTTAB_KEY="/FIXME-initramfs-rootmnt$_CRYPTTAB_KEY" # preserve mangled name
                fi
        esac
    fi

    if [ -n "${CRYPTTAB_OPTION_keyscript+x}" ]; then
        copy_exec "$CRYPTTAB_OPTION_keyscript"
    fi
    if [ "${CRYPTTAB_OPTION_keyscript-}" = "/lib/cryptsetup/scripts/decrypt_derived" ]; then
        # (recursively) list first the device to derive the key from (so
        # the boot scripts unlock it first); since _CRYPTTAB_* are local
        # to crypttab_find_and_print_entry() the new value won't
        # override the new ones
        crypttab_find_and_print_entry "$CRYPTTAB_KEY"
    fi
    printf '%s %s %s %s\n' \
        "$_CRYPTTAB_NAME" "$_CRYPTTAB_SOURCE" "$_CRYPTTAB_KEY" "$_CRYPTTAB_OPTIONS" >&3
}

# get_cryptdevs($maj:$min, [$maj:$min ..])
#   Print the list of crypttab(5) entries to FD nr. 3, for dm-crypt
#   devices holding any of the given devices (which can be an md, a lv,
#   a mapped device, or a regular block device).
get_cryptdevs() {
    local devno base
    for devno in "$@"; do
        base="/sys/dev/block/$devno"
        if [ ! -d "$base" ]; then
            cryptsetup_message "ERROR: Couldn't find sysfs directory for $devno"
            return 1
        fi
        get_dmcrypt_slaves "$base"
    done
}

# get_resume_devno()
#   Return the device ID(s) used for system suspend/hibernate.
get_resume_devno() {
    local dev filename

    # uswsusp
    for filename in /etc/uswsusp.conf /etc/suspend.conf; do
        [ -e "$filename" ] || continue
        dev="$(sed -nr '/^resume device\s*[:=]\s*/ {s///p;q}' "$filename")"
        if [ -n "$dev" ] && [ "$dev" != "<path_to_resume_device_file>" ]; then
            # trim quotes
            dev="$(printf '%s' "$dev" | sed -re 's/^"(.*)"\s*$/\1/' -e "s/^'(.*)'\\s*$/\\1/")"
            print_devno "$(printf '%b' "$dev")" # unmangle
        fi
    done

    # regular swsusp
    dev="$(sed -nr 's,^(.*\s)?resume=(\S+)(\s.*)?$,\2,p' /proc/cmdline)"
    dev="$(printf '%b' "$dev")" # unmangle
    print_devno "$(printf '%b' "$dev")" # unmangle

    # initramfs-tools >=0.129
    dev="${RESUME:-auto}"
    if [ "$dev" != none ]; then
        if [ "$dev" = auto ]; then
            # next line from /usr/share/initramfs-tools/hooks/resume
            dev="$(grep ^/dev/ /proc/swaps | sort -rnk3 | head -n 1 | cut -d " " -f 1)"
        fi
        print_devno "$(printf '%b' "$dev")" # unmangle
    fi
}
print_devno() {
    local DEV MAJ MIN # locally scope the 3 variables resolve_device() sets
    if [ -n "$1" ] && resolve_device "$1"; then
        printf '%d:%d\n' "$MAJ" "$MIN"
    fi
}

# crypttab_print_initramfs_entry()
#   Print a crypttab(5) entry - unless it was already processed - if it
#   has the 'initramfs' option set.
crypttab_print_initramfs_entry() {
    local usage=
    if ! grep -Fxqz -e "$CRYPTTAB_NAME" -- "$DESTDIR/cryptroot/targets" &&
            crypttab_parse_options --quiet &&
            [ "${CRYPTTAB_OPTION_initramfs-no}" = "yes" ]; then
        printf '%s\0' "$CRYPTTAB_NAME" >>"$DESTDIR/cryptroot/targets"
        crypttab_print_entry
    fi
}

# generate_initrd_crypttab()
#   Generate the crypttab(5) snippet that is relevant at initramfs
#   stage.  (Devices that aren't required at initramfs stage are
#   ignored.)
generate_initrd_crypttab() {
    local devnos usage IFS="$(printf '\t\n ')"
    mkdir -- "$DESTDIR/cryptroot"
    true >"$DESTDIR/cryptroot/targets"

    {
        if devnos="$(get_mnt_devno /)"; then
            usage=rootfs get_cryptdevs $devnos
        else
            cryptsetup_message "WARNING: Couldn't determine root device"
        fi

        if devnos="$(get_resume_devno)"; then
            usage=resume get_cryptdevs $devnos
        fi

        if devnos="$(get_mnt_devno /usr)"; then
            usage="" get_cryptdevs $devnos
        fi

        # add crypttab entries with the 'initramfs' option set
        crypttab_foreach_entry crypttab_print_initramfs_entry
    } 3>"$DESTDIR/cryptroot/crypttab"
    rm -f "$DESTDIR/cryptroot/targets"
}

# populate_CRYPTO_MODULES()
#   Find out which crypto modules are required for a crypttab(5) entry,
#   and append them to the CRYPTO_MODULES variable.
populate_CRYPTO_MODULES() {
    local cipher iv

    # cf. dmsetup(8) and https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt
    cipher="$(dmsetup table --target crypt -- "$CRYPTTAB_NAME" | cut -d' ' -f4)"
    if [ -z "$cipher" ]; then
        cryptsetup_message "WARNING: Couldn't determine cipher modules to load for $CRYPTTAB_NAME"
    elif [ "${cipher#capi:}" = "$cipher" ]; then
        # direct specification "cipher[:keycount]-chainmode-ivmode[:ivopts]"
        CRYPTO_MODULES="${CRYPTO_MODULES:+$CRYPTO_MODULES }${cipher%%[-:]*}" # cipher
        cipher="${cipher#"${cipher%%-*}-"}" # chainmode-ivmode[:ivopts]"
        CRYPTO_MODULES="${CRYPTO_MODULES:+$CRYPTO_MODULES }${cipher%-*}" # chainmode
        iv="${cipher##*-}" # ivmode[:ivopts]"
        if [ "${iv#*:}" != "$iv" ]; then
            CRYPTO_MODULES="${CRYPTO_MODULES:+$CRYPTO_MODULES }${iv#*:}" # ivopts
        fi
    else
        # kernel crypto API format "capi:cipher_api_spec-ivmode[:ivopts]", since linux 4.12
        cipher="${cipher#capi:}"
        cryptsetup_message "WARNING: Couldn't determine cipher modules to load for $CRYPTTAB_NAME" \
            "(kernel crypto API format isn't supported yet)"
    fi
}

# add_modules($glob, $moduledir, [$moduledir ..])
#   Add modules matching under the given $moduledir(s), the name of
#   which matching $glob.
#   Return 0 if any module was found found, 1 if not.
add_modules() {
    local glob="$1" found=n
    shift
    for mod in $(find -H "$@" -name "$glob.ko" -type f -printf '%f\n'); do
        manual_add_modules "${mod%.ko}"
        found=y
    done
    [ "$found" = y ] && return 0 || return 1
}

# add_crypto_modules($name, [$name ..])
#   Determine kernel module name and add to initramfs.
add_crypto_modules() {
    local mod
    for mod in "$@"; do
        # We have several potential sources of modules (in order of preference):
        #
        #   a) /lib/modules/$VERSION/kernel/arch/$ARCH/crypto/$mod-$specific.ko
        #   b) /lib/modules/$VERSION/kernel/crypto/$mod_generic.ko
        #   c) /lib/modules/$VERSION/kernel/crypto/$mod.ko
        #
        # and (currently ignored):
        #
        #   d) /lib/modules/$VERSION/kernel/drivers/crypto/$specific-$mod.ko
        add_modules "$mod-*" "$MODULESDIR"/kernel/arch/*/crypto || true
        add_modules "${mod}_generic" "$MODULESDIR/kernel/crypto" \
            || add_modules "$mod" "$MODULESDIR/kernel/crypto" \
            || true
    done
}


#######################################################################
# Begin real processing

unset -v CRYPTSETUP KEYFILE_PATTERN
KEYFILE_PATTERN=

# Load the hook config
if [ -f "/etc/cryptsetup-initramfs/conf-hook" ]; then
    . /etc/cryptsetup-initramfs/conf-hook
fi

if [ "${CRYPTSETUP-}" = "n" ] || [ "${CRYPTSETUP-}" = "N" ]; then
    # XXX post-Buster: remove this warning and the auto-detection logic below
    cryptsetup_message "WARNING: Honoring CRYPTSETUP=\"n\" will deprecated in the future." \
        "Please uninstall the 'cryptsetup-initramfs' package instead" \
        "if you don't want the cryptsetup initramfs integration."
    exit 0
fi

if [ -n "$KEYFILE_PATTERN" ]; then
    case "${UMASK:-$(umask)}" in
        0[0-7]77) ;;
        *) cryptsetup_message "WARNING: Permissive UMASK (${UMASK:-$(umask)})." \
                "Private key material within the initrd might be left unprotected."
        ;;
    esac
fi

CRYPTO_MODULES=
if [ -r "$TABFILE" ]; then
    generate_initrd_crypttab
    TABFILE="$DESTDIR/cryptroot/crypttab"
    crypttab_foreach_entry populate_CRYPTO_MODULES
fi

# per comment in the config file a non-empty KEYFILE_PATTERN value
# implies CRYPTSETUP=y
if [ -z "${CRYPTSETUP-}" ] && [ -z "${KEYFILE_PATTERN-}" ] && [ -z "$CRYPTO_MODULES" ]; then
    cryptsetup_message "WARNING: The initramfs image may not contain cryptsetup binaries nor crypto modules." \
        "If that's on purpose, you may want to uninstall the 'cryptsetup-initramfs' package in" \
        "order to disable the cryptsetup initramfs integration and avoid this warning."
else
    # add required components
    manual_add_modules dm_mod
    manual_add_modules dm_crypt

    copy_exec /sbin/cryptsetup
    copy_exec /sbin/dmsetup
    copy_exec /lib/cryptsetup/askpass

    # libargon2 uses pthread_cancel
    LIBC_DIR="$(ldd /sbin/cryptsetup | sed -nr 's#.* => (/lib.*)/libc\.so\.[0-9.-]+ \(0x[[:xdigit:]]+\)$#\1#p')"
    find -L "$LIBC_DIR" -maxdepth 1 -name 'libgcc_s.*' -type f | while read so; do
        copy_exec "$so"
    done

    # We need sed. Either via busybox or as standalone binary.
    if [ "$BUSYBOX" = n ] || [ ! -e "$BUSYBOXDIR/busybox" ]; then
        copy_exec /bin/sed
    fi

    # detect whether the host CPU has AES-NI support
    if grep -Eq '^flags\s*:(.*\s)?aes(\s.*)?$' /proc/cpuinfo; then
        CRYPTO_MODULES="${CRYPTO_MODULES:+$CRYPTO_MODULES }aesni"
    fi

    # add userspace crypto module (only required for opening LUKS2 devices
    # we add the module unconditionally as it's the default format)
    CRYPTO_MODULES="${CRYPTO_MODULES:+$CRYPTO_MODULES }algif_skcipher"

    if [ "$MODULES" = most ]; then
        for d in "$MODULESDIR"/kernel/arch/*/crypto; do
            copy_modules_dir "${d#"$MODULESDIR/"}"
        done
        copy_modules_dir "kernel/crypto"
    else
        if [ "$MODULES" != "dep" ]; then
            # with large initramfs, we always add a basic subset of modules
            add_crypto_modules aes cbc chainiv cryptomgr krng sha256 xts
        fi
        add_crypto_modules $(printf '%s' "${CRYPTO_MODULES-}" | tr ' ' '\n' | sort -u)
    fi
    copy_file library /lib/cryptsetup/functions /lib/cryptsetup/functions
fi