Add initramfs-tools hooks

[diabonas]

In order to display the TOTP during boot on Debian/Ubuntu/..., add initramfs-tools hooks to add (plymouth-)tpm2-totp to the initramfs generated by these distributions.

[diabonas]

From reading the initramfs-tools man page, I think something like this should work:

/etc/initramfs-tools/hooks/tpm2-totp

#!/bin/sh

PREREQ='plymouth'
prereqs() {
    echo "$PREREQ"
}

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

. /usr/share/initramfs-tools/hook-functions

copy_exec @LIBEXECDIR@/plymouth-tpm2-totp /bin
copy_modules_dir kernel/drivers/char/tpm

/etc/initramfs-tools/scripts/init-premount/tpm2-totp

#!/bin/sh

PREREQ='plymouth'
prereqs() {
    echo "$PREREQ"
}

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

for arg in $(cat /proc/cmdline); do
    case "$arg" in
        rd.tpm2-totp.nvindex=*)
            nvindex="${arg#rd.tpm2-totp.nvindex=}"
            ;;
    esac
done

TSS2_LOG=esys+error /bin/plymouth-tpm2-totp ${nvindex:+--nvindex "$nvindex"} &

Note that this is completely untested since I don't have a distribution using initramfs-tools.

For integrating this into the build system, something similar to the existing mkinitcpio hooks should work:

configure.ac

AC_CHECK_PROG([mkinitramfs], [mkinitramfs], [yes])
AC_ARG_WITH([mkinitramfstoolsdir],
            AS_HELP_STRING([--with-initramfstoolsdir=DIR], [directory for initramfs-tools scripts]),,
            [AS_IF([test "x$mkinitramfs" = xyes], [with_initramfstoolsdir=$sysconfdir/initramfs-tools])])
AM_CONDITIONAL(HAVE_INITRAMFSTOOLS, [test -n "$with_initramfstoolsdir" -a "x$with_initramfstoolsdir" != xno])
AM_COND_IF([HAVE_INITRAMFSTOOLS],
           [AC_SUBST([initramfstools_hooksdir], [$with_initramfstoolsdir/hooks])
            AC_SUBST([initramfstools_scriptsdir], [$with_initramfstoolsdir/scripts/init-premount])
])

Makefile.am

if HAVE_INITRAMFSTOOLS
if HAVE_PLYMOUTH
initramfstools_hooks_DATA = dist/initramfs-tools/hooks/tpm2-totp
initramfstools_scripts_DATA = dist/initramfs-tools/scripts/init-premount/tpm2-totp
endif # HAVE_PLYMOUTH
endif # HAVE_INITRAMFSTOOLS
EXTRA_DIST += dist/initramfs-tools/scripts/init-premount/tpm2-totp

[diabonas]

If anybody is interested in testing this, I have setup a new branch at https://github.com/diabonas/tpm2-totp/tree/initramfs-tools. Compile and install it with

git clone --branch initramfs-tools https://github.com/diabonas/tpm2-totp.git
cd tpm2-totp
./bootstrap
./configure --sysconfdir=/etc
make
sudo make install
tpm2-totp generate

I don't expect this to work out of the box, but I appreciate any testing feedback.