lbmk/resources/scripts/update/module/mrc

#!/usr/bin/env sh

# Download Intel MRC images
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, version 2 of the License.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

[ "x${DEBUG+set}" = 'xset' ] && set -v
set -u -e
export PATH="${PATH}:/sbin"

# This file is forked from util/chromeos/crosfirmware.sh in coreboot cfc26ce278
# Changes to it in *this version* are copyright 2021 and 2023 Leah Rowe, under
# the same license as above.

# use updated manifest from wayback machine, when updating mrc.bin,
# and update the other variables below accordingly. current manifest used:
# https://web.archive.org/web/20210211071412/https://dl.google.com/dl/edgedl/chromeos/recovery/recovery.conf

# the wayback machine is used so that we get the same manifest. google
# does not seem to version the manifest, but archives are available

# variables taken from that manifest:

_board="peppy"
_file="chromeos_12239.92.0_peppy_recovery_stable-channel_mp-v3.bin"
_url="https://dl.google.com/dl/edgedl/chromeos/recovery/chromeos_12239.92.0_peppy_recovery_stable-channel_mp-v3.bin.zip"
_url2="https://web.archive.org/web/20200516070928/https://dl.google.com/dl/edgedl/chromeos/recovery/chromeos_12239.92.0_peppy_recovery_stable-channel_mp-v3.bin.zip"
_sha1sum="cd5917cbe7f821ad769bf0fd87046898f9e175c8"
_mrc_complete_hash="d18de1e3d52c0815b82ea406ca07897c56c65696"
_mrc_complete="mrc/haswell/mrc.bin"

cbdir="coreboot/default"
cbfstool="cbutils/default/cbfstool"

sname=""

main()
{
	sname=${0}
	printf "Downloading Intel MRC blobs\n"

	check_existing && exit 0
	build_dependencies || fail "could not build dependencies"
	fetch_mrc || fail "could not fetch mrc.bin"
}

check_existing()
{
	if [ ! -f ${_mrc_complete} ]; then
		return 1
	fi
	printf 'found existing mrc.bin, checking its hash\n'
	if [ "$(sha1sum ${_mrc_complete} | awk '{print $1}')" \
			= "${_mrc_complete_hash}" ]; then
		printf 'checksums matched, skipping downloading\n'
		return 0
	else
		printf 'hashes did not match, starting over\n'
		return 1
	fi
}

build_dependencies()
{
	if [ ! -d "${cbdir}/" ]; then
	    ./fetch_trees coreboot default || return 1
	fi
	./build module cbutils default || return 1
	return 0
}

fetch_mrc()
{
	mkdir -p mrc/haswell/ || return 1

	(
	cd mrc/haswell/

	download_image ${_url} ${_file} ${_sha1sum}
	if [ ! -f ${_file} ]; then
		download_image ${_url2} ${_file} ${_sha1sum}
	fi
	if [ ! -f $_file ]; then
		fail "%{_file} not downloaded / verification failed."
	fi

	extract_partition ROOT-A ${_file} root-a.ext2
	extract_shellball root-a.ext2 chromeos-firmwareupdate-${_board}

	extract_coreboot chromeos-firmwareupdate-${_board}

	../../${cbfstool} coreboot-*.bin extract -f mrc.bin \
			-n mrc.bin -r RO_SECTION \
					|| fail "Could not fetch mrc.bin"
	rm -f "chromeos-firmwareupdate-${_board}" coreboot-*.bin \
			"${_file}" "root-a.ext2"

	printf "\n\nmrc.bin saved to ${_mrc_complete}\n\n"
	)

	return 0
}

download_image()
{
	url=${1}
	_file=${2}
	_sha1sum=${3}

	echo "Downloading recovery image"
	curl "$url" > "$_file.zip"
	if [ "$(sha1sum ${_file}.zip | awk '{print $1}')" = "${_sha1sum}" ]
	then
		unzip -q "${_file}.zip"
		rm "${_file}.zip"
		echo "Checksum verification passed for recovery image."
		return 0
	else
		rm "${_file}.zip"
		echo "Bad checksum. Recovery image deleted."
		return 1
	fi
}

extract_partition()
{
	NAME=${1}
	FILE=${2}
	ROOTFS=${3}
	_bs=1024

	echo "Extracting ROOT-A partition"
	ROOTP=$( printf "unit\nB\nprint\nquit\n" | \
		 parted ${FILE} 2>/dev/null | grep ${NAME} )

	START=$(( $( echo ${ROOTP} | cut -f2 -d\ | tr -d "B" ) ))
	SIZE=$(( $( echo ${ROOTP} | cut -f4 -d\ | tr -d "B" ) ))

	dd if=${FILE} of=${ROOTFS} bs=${_bs} skip=$(( ${START} / ${_bs} )) \
		count=$(( ${SIZE} / ${_bs} ))  > /dev/null
}

extract_shellball()
{
	ROOTFS=${1}
	SHELLBALL=${2}

	echo "Extracting chromeos-firmwareupdate"
	printf "cd /usr/sbin\ndump chromeos-firmwareupdate ${SHELLBALL}\nquit" \
		| debugfs ${ROOTFS} > /dev/null 2>&1
}

extract_coreboot()
{
	_shellball=${1}
	_unpacked=$( mktemp -d )

	echo "Extracting coreboot image"
	sh ${_shellball} --unpack ${_unpacked} > /dev/null

	_version=$( cat ${_unpacked}/VERSION | grep BIOS\ version: | \
			cut -f2 -d: | tr -d \  )

	cp ${_unpacked}/bios.bin coreboot-${_version}.bin
	rm -r "${_unpacked}"
}

fail()
{
	printf "%s: ERROR: %s\n"
			${sname} ${1}
	exit 1
}

main $@