meta-security/classes/dm-verity-img.bbclass - mdmillerii/openbmc - Gitiles

 # SPDX-License-Identifier: MIT
 #
 # Copyright (C) 2020 BayLibre SAS
 # Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
 #
 # This bbclass allows creating of dm-verity protected partition images. It
 # generates a device image file with dm-verity hash data appended at the end
 # plus the corresponding .env file containing additional information needed
 # to mount the image such as the root hash in the form of ell variables. To
 # assure data integrity, the root hash must be stored in a trusted location
 # or cryptographically signed and verified.
 #
 # Optionally, we can store the hash data on a separate device or partition
 # for improved compartmentalization and ease of use/deployment.
 #
 # Usage:
 #     DM_VERITY_IMAGE = "core-image-full-cmdline" # or other image
 #     DM_VERITY_IMAGE_TYPE = "ext4" # or ext2, ext3 & btrfs
 #     DM_VERITY_SEPARATE_HASH = "1" # optional; store hash on separate dev
 #     IMAGE_CLASSES += "dm-verity-img"
 #
 # Using the GPT UUIDs specified in the standard can also be useful in that
 # they are displayed and translated in cfdisk output.
 #
 #     DM_VERITY_ROOT_GUID = <UUID for your architecture and root-fs>
 #     DM_VERITY_RHASH_GUID = <UUID for your architecture and verity-hash>
 # https://uapi-group.org/specifications/specs/discoverable_partitions_specification/

 # The resulting image can then be used to implement the device mapper block
 # integrity checking on the target device.

 # Define the location where the DM_VERITY_IMAGE specific dm-verity root hash
 # is stored where it can be installed into associated initramfs rootfs.
 STAGING_VERITY_DIR ?= "${TMPDIR}/work-shared/${MACHINE}/dm-verity"

 # location of images, default current image recipe. Set to DEPLOY_DIR_IMAGE
 # if non-verity images want to embed the .wks and verity image.
 DM_VERITY_DEPLOY_DIR ?= "${IMGDEPLOYDIR}"

 # Define the data block size to use in veritysetup.
 DM_VERITY_IMAGE_DATA_BLOCK_SIZE ?= "1024"

 # Define the hash block size to use in veritysetup.
 DM_VERITY_IMAGE_HASH_BLOCK_SIZE ?= "4096"

 # Should we store the hash data on a separate device/partition?
 DM_VERITY_SEPARATE_HASH ?= "0"

 # These are arch specific.  We could probably intelligently auto-assign these?
 # Take x86-64 values as defaults. No impact on functionality currently.
 # See SD_GPT_ROOT_X86_64 and SD_GPT_ROOT_X86_64_VERITY in the spec.
 # Note - these are passed directly to sgdisk so hyphens needed.
 DM_VERITY_ROOT_GUID ?= "4f68bce3-e8cd-4db1-96e7-fbcaf984b709"
 DM_VERITY_RHASH_GUID ?= "2c7357ed-ebd2-46d9-aec1-23d437ec2bf5"

 DEPENDS += "bc-native"

 # Process the output from veritysetup and generate the corresponding .env
 # file. The output from veritysetup is not very machine-friendly so we need to
 # convert it to some better format. Let's drop the first line (doesn't contain
 # any useful info) and feed the rest to a script.
 process_verity() {
     local ENV="${STAGING_VERITY_DIR}/${IMAGE_BASENAME}.$TYPE.verity.env"
     local WKS_INC="${STAGING_VERITY_DIR}/${IMAGE_BASENAME}.$TYPE.wks.in"
     rm -f $ENV

     # Each line contains a key and a value string delimited by ':'. Read the
     # two parts into separate variables and process them separately. For the
     # key part: convert the names to upper case and replace spaces with
     # underscores to create correct shell variable names. For the value part:
     # just trim all white-spaces.
     IFS=":"
     while read KEY VAL; do
         printf '%s=%s\n' \
             "$(echo "$KEY" | tr '[:lower:]' '[:upper:]' | sed 's/ /_/g')" \
             "$(echo "$VAL" | tr -d ' \t')" >> $ENV
     done

     # Add partition size
     echo "DATA_SIZE=$SIZE" >> $ENV

     # Add whether we are storing the hash data separately
     echo "SEPARATE_HASH=${DM_VERITY_SEPARATE_HASH}" >> $ENV

     # Configured for single partition use of veritysetup?  OK, we are done.
     if [ ${DM_VERITY_SEPARATE_HASH} -eq 0 ]; then
         return
     fi

     # Craft up the UUIDs that are part of the verity standard for root & hash
     # while we are here and in shell.  Re-read our output to get ROOT_HASH
     # and then cut it in 1/2 ; HI for data UUID and LO for hash-data UUID.
     # https://uapi-group.org/specifications/specs/discoverable_partitions_specification/

     ROOT_HASH=$(cat $ENV | grep ^ROOT_HASH | sed 's/ROOT_HASH=//' | tr a-f A-F)
     ROOT_HI=$(echo "obase=16;ibase=16;$ROOT_HASH/2^80" | bc)
     ROOT_LO=$(echo "obase=16;ibase=16;$ROOT_HASH%2^80" | bc)

     # Hyphenate as per UUID spec and as expected by wic+sgdisk parameters.
     # Prefix with leading zeros, in case hash chunks weren't using highest bits
     # "bc" needs upper case, /dev/disk/by-partuuid/ is lower case. <sigh>
     ROOT_UUID=$(echo 00000000$ROOT_HI | sed 's/.*\(.\{32\}\)$/\1/' | \
         sed 's/./-&/9;s/./-&/14;s/./-&/19;s/./-&/24' | tr A-F a-f )
     RHASH_UUID=$(echo 00000000$ROOT_LO | sed 's/.*\(.\{32\}\)$/\1/' | \
         sed 's/./-&/9;s/./-&/14;s/./-&/19;s/./-&/24' | tr A-F a-f )

     # Emit the values needed for a veritysetup run in the initramfs
     echo "ROOT_UUID=$ROOT_UUID" >> $ENV
     echo "RHASH_UUID=$RHASH_UUID" >> $ENV

     # Create wks.in fragment with build specific UUIDs for partitions.
     # Unfortunately the wks.in does not support line continuations...
     # First, the unappended filesystem data partition.
     echo 'part / --source rawcopy --ondisk sda --sourceparams="file=${DM_VERITY_DEPLOY_DIR}/${DM_VERITY_IMAGE}-${MACHINE}.rootfs.${DM_VERITY_IMAGE_TYPE}.verity" --part-name verityroot --part-type="${DM_VERITY_ROOT_GUID}"'" --uuid=\"$ROOT_UUID\"" > $WKS_INC

     # note: no default mount point for hash data partition
     echo 'part --source rawcopy --ondisk sda --sourceparams="file=${DM_VERITY_DEPLOY_DIR}/${DM_VERITY_IMAGE}-${MACHINE}.${DM_VERITY_IMAGE_TYPE}.vhash" --part-name verityhash --part-type="${DM_VERITY_RHASH_GUID}"'" --uuid=\"$RHASH_UUID\"" >> $WKS_INC
 }

 verity_setup() {
     local TYPE=$1
     local INPUT=${IMAGE_NAME}.$TYPE
     local SIZE=$(stat --printf="%s" $INPUT)
     local OUTPUT=$INPUT.verity
     local OUTPUT_HASH=$INPUT.verity
     local HASH_OFFSET=""
     local SETUP_ARGS=""
     local SAVED_ARGS="${STAGING_VERITY_DIR}/${IMAGE_BASENAME}.$TYPE.verity.args"

     install -d ${STAGING_VERITY_DIR}

     if [ ${DM_VERITY_IMAGE_DATA_BLOCK_SIZE} -ge ${DM_VERITY_IMAGE_HASH_BLOCK_SIZE} ]; then
         align=${DM_VERITY_IMAGE_DATA_BLOCK_SIZE}
     else
         align=${DM_VERITY_IMAGE_HASH_BLOCK_SIZE}
     fi
     SIZE=$(expr \( $SIZE + $align - 1 \) / $align \* $align)

     # Assume some users may want separate hash vs. appended hash
     if [ ${DM_VERITY_SEPARATE_HASH} -eq 1 ]; then
         OUTPUT_HASH=$INPUT.vhash
     else
         HASH_OFFSET="--hash-offset="$SIZE
     fi

     cp -a $INPUT $OUTPUT

     SETUP_ARGS=" \
         --data-block-size=${DM_VERITY_IMAGE_DATA_BLOCK_SIZE} \
         --hash-block-size=${DM_VERITY_IMAGE_HASH_BLOCK_SIZE} \
         $HASH_OFFSET format $OUTPUT $OUTPUT_HASH \
     "

     echo "veritysetup $SETUP_ARGS" > $SAVED_ARGS

     # Let's drop the first line of output (doesn't contain any useful info)
     # and feed the rest to another function.
     veritysetup $SETUP_ARGS | tail -n +2 | process_verity
 }

 # make "dateless" symlink for the hash so the wks can find it.
 verity_hash() {
     cd ${IMGDEPLOYDIR}
     ln -sf ${IMAGE_NAME}.${DM_VERITY_IMAGE_TYPE}.vhash \
         ${IMAGE_BASENAME}-${MACHINE}.${DM_VERITY_IMAGE_TYPE}.vhash
 }

 VERITY_TYPES = " \
     ext2.verity ext3.verity ext4.verity \
     btrfs.verity \
     erofs.verity erofs-lz4.verity erofs-lz4hc.verity \
     squashfs.verity squashfs-xz.verity squashfs-lzo.verity squashfs-lz4.verity squashfs-zst.verity \
 "
 IMAGE_TYPES += "${VERITY_TYPES}"
 CONVERSIONTYPES += "verity"
 CONVERSION_CMD:verity = "verity_setup ${type}"
 CONVERSION_DEPENDS_verity = "cryptsetup-native"
 IMAGE_CMD:vhash = "verity_hash"

 python __anonymous() {
     verity_image = d.getVar('DM_VERITY_IMAGE')
     verity_type = d.getVar('DM_VERITY_IMAGE_TYPE')
     verity_hash = d.getVar('DM_VERITY_SEPARATE_HASH')
     image_fstypes = d.getVar('IMAGE_FSTYPES')
     pn = d.getVar('PN')

     if not verity_image or not verity_type:
         bb.warn('dm-verity-img class inherited but not used')
         return

     if verity_image != pn:
         return # This doesn't concern this image

     if len(verity_type.split()) != 1:
         bb.fatal('DM_VERITY_IMAGE_TYPE must contain exactly one type')

     d.appendVar('IMAGE_FSTYPES', ' %s.verity' % verity_type)
     if verity_hash == "1":
         d.appendVar('IMAGE_FSTYPES', ' vhash')

     # If we're using wic: we'll have to use partition images and not the rootfs
     # source plugin so add the appropriate dependency.
     if 'wic' in image_fstypes:
         dep = ' %s:do_image_%s' % (pn, verity_type.replace("-", "_"))
         d.appendVarFlag('do_image_wic', 'depends', dep)
 }
	# SPDX-License-Identifier: MIT
	#
	# Copyright (C) 2020 BayLibre SAS
	# Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
	#
	# This bbclass allows creating of dm-verity protected partition images. It
	# generates a device image file with dm-verity hash data appended at the end
	# plus the corresponding .env file containing additional information needed
	# to mount the image such as the root hash in the form of ell variables. To
	# assure data integrity, the root hash must be stored in a trusted location
	# or cryptographically signed and verified.
	#
	# Optionally, we can store the hash data on a separate device or partition
	# for improved compartmentalization and ease of use/deployment.
	#
	# Usage:
	# DM_VERITY_IMAGE = "core-image-full-cmdline" # or other image
	# DM_VERITY_IMAGE_TYPE = "ext4" # or ext2, ext3 & btrfs
	# DM_VERITY_SEPARATE_HASH = "1" # optional; store hash on separate dev
	# IMAGE_CLASSES += "dm-verity-img"
	#
	# Using the GPT UUIDs specified in the standard can also be useful in that
	# they are displayed and translated in cfdisk output.
	#
	# DM_VERITY_ROOT_GUID = <UUID for your architecture and root-fs>
	# DM_VERITY_RHASH_GUID = <UUID for your architecture and verity-hash>
	# https://uapi-group.org/specifications/specs/discoverable_partitions_specification/

	# The resulting image can then be used to implement the device mapper block
	# integrity checking on the target device.

	# Define the location where the DM_VERITY_IMAGE specific dm-verity root hash
	# is stored where it can be installed into associated initramfs rootfs.
	STAGING_VERITY_DIR ?= "${TMPDIR}/work-shared/${MACHINE}/dm-verity"

	# location of images, default current image recipe. Set to DEPLOY_DIR_IMAGE
	# if non-verity images want to embed the .wks and verity image.
	DM_VERITY_DEPLOY_DIR ?= "${IMGDEPLOYDIR}"

	# Define the data block size to use in veritysetup.
	DM_VERITY_IMAGE_DATA_BLOCK_SIZE ?= "1024"

	# Define the hash block size to use in veritysetup.
	DM_VERITY_IMAGE_HASH_BLOCK_SIZE ?= "4096"

	# Should we store the hash data on a separate device/partition?
	DM_VERITY_SEPARATE_HASH ?= "0"

	# These are arch specific. We could probably intelligently auto-assign these?
	# Take x86-64 values as defaults. No impact on functionality currently.
	# See SD_GPT_ROOT_X86_64 and SD_GPT_ROOT_X86_64_VERITY in the spec.
	# Note - these are passed directly to sgdisk so hyphens needed.
	DM_VERITY_ROOT_GUID ?= "4f68bce3-e8cd-4db1-96e7-fbcaf984b709"
	DM_VERITY_RHASH_GUID ?= "2c7357ed-ebd2-46d9-aec1-23d437ec2bf5"

	DEPENDS += "bc-native"

	# Process the output from veritysetup and generate the corresponding .env
	# file. The output from veritysetup is not very machine-friendly so we need to
	# convert it to some better format. Let's drop the first line (doesn't contain
	# any useful info) and feed the rest to a script.
	process_verity() {
	local ENV="${STAGING_VERITY_DIR}/${IMAGE_BASENAME}.$TYPE.verity.env"
	local WKS_INC="${STAGING_VERITY_DIR}/${IMAGE_BASENAME}.$TYPE.wks.in"
	rm -f $ENV

	# Each line contains a key and a value string delimited by ':'. Read the
	# two parts into separate variables and process them separately. For the
	# key part: convert the names to upper case and replace spaces with
	# underscores to create correct shell variable names. For the value part:
	# just trim all white-spaces.
	IFS=":"
	while read KEY VAL; do
	printf '%s=%s\n' \
	"$(echo "$KEY" \| tr '[:lower:]' '[:upper:]' \| sed 's/ /_/g')" \
	"$(echo "$VAL" \| tr -d ' \t')" >> $ENV
	done

	# Add partition size
	echo "DATA_SIZE=$SIZE" >> $ENV

	# Add whether we are storing the hash data separately
	echo "SEPARATE_HASH=${DM_VERITY_SEPARATE_HASH}" >> $ENV

	# Configured for single partition use of veritysetup? OK, we are done.
	if [ ${DM_VERITY_SEPARATE_HASH} -eq 0 ]; then
	return
	fi

	# Craft up the UUIDs that are part of the verity standard for root & hash
	# while we are here and in shell. Re-read our output to get ROOT_HASH
	# and then cut it in 1/2 ; HI for data UUID and LO for hash-data UUID.
	# https://uapi-group.org/specifications/specs/discoverable_partitions_specification/

	ROOT_HASH=$(cat $ENV \| grep ^ROOT_HASH \| sed 's/ROOT_HASH=//' \| tr a-f A-F)
	ROOT_HI=$(echo "obase=16;ibase=16;$ROOT_HASH/2^80" \| bc)
	ROOT_LO=$(echo "obase=16;ibase=16;$ROOT_HASH%2^80" \| bc)

	# Hyphenate as per UUID spec and as expected by wic+sgdisk parameters.
	# Prefix with leading zeros, in case hash chunks weren't using highest bits
	# "bc" needs upper case, /dev/disk/by-partuuid/ is lower case. <sigh>
	ROOT_UUID=$(echo 00000000$ROOT_HI \| sed 's/.*\(.\{32\}\)$/\1/' \| \
	sed 's/./-&/9;s/./-&/14;s/./-&/19;s/./-&/24' \| tr A-F a-f )
	RHASH_UUID=$(echo 00000000$ROOT_LO \| sed 's/.*\(.\{32\}\)$/\1/' \| \
	sed 's/./-&/9;s/./-&/14;s/./-&/19;s/./-&/24' \| tr A-F a-f )

	# Emit the values needed for a veritysetup run in the initramfs
	echo "ROOT_UUID=$ROOT_UUID" >> $ENV
	echo "RHASH_UUID=$RHASH_UUID" >> $ENV

	# Create wks.in fragment with build specific UUIDs for partitions.
	# Unfortunately the wks.in does not support line continuations...
	# First, the unappended filesystem data partition.
	echo 'part / --source rawcopy --ondisk sda --sourceparams="file=${DM_VERITY_DEPLOY_DIR}/${DM_VERITY_IMAGE}-${MACHINE}.rootfs.${DM_VERITY_IMAGE_TYPE}.verity" --part-name verityroot --part-type="${DM_VERITY_ROOT_GUID}"'" --uuid=\"$ROOT_UUID\"" > $WKS_INC

	# note: no default mount point for hash data partition
	echo 'part --source rawcopy --ondisk sda --sourceparams="file=${DM_VERITY_DEPLOY_DIR}/${DM_VERITY_IMAGE}-${MACHINE}.${DM_VERITY_IMAGE_TYPE}.vhash" --part-name verityhash --part-type="${DM_VERITY_RHASH_GUID}"'" --uuid=\"$RHASH_UUID\"" >> $WKS_INC
	}

	verity_setup() {
	local TYPE=$1
	local INPUT=${IMAGE_NAME}.$TYPE
	local SIZE=$(stat --printf="%s" $INPUT)
	local OUTPUT=$INPUT.verity
	local OUTPUT_HASH=$INPUT.verity
	local HASH_OFFSET=""
	local SETUP_ARGS=""
	local SAVED_ARGS="${STAGING_VERITY_DIR}/${IMAGE_BASENAME}.$TYPE.verity.args"

	install -d ${STAGING_VERITY_DIR}

	if [ ${DM_VERITY_IMAGE_DATA_BLOCK_SIZE} -ge ${DM_VERITY_IMAGE_HASH_BLOCK_SIZE} ]; then
	align=${DM_VERITY_IMAGE_DATA_BLOCK_SIZE}
	else
	align=${DM_VERITY_IMAGE_HASH_BLOCK_SIZE}
	fi
	SIZE=$(expr \( $SIZE + $align - 1 \) / $align \* $align)

	# Assume some users may want separate hash vs. appended hash
	if [ ${DM_VERITY_SEPARATE_HASH} -eq 1 ]; then
	OUTPUT_HASH=$INPUT.vhash
	else
	HASH_OFFSET="--hash-offset="$SIZE
	fi

	cp -a $INPUT $OUTPUT

	SETUP_ARGS=" \
	--data-block-size=${DM_VERITY_IMAGE_DATA_BLOCK_SIZE} \
	--hash-block-size=${DM_VERITY_IMAGE_HASH_BLOCK_SIZE} \
	$HASH_OFFSET format $OUTPUT $OUTPUT_HASH \
	"

	echo "veritysetup $SETUP_ARGS" > $SAVED_ARGS

	# Let's drop the first line of output (doesn't contain any useful info)
	# and feed the rest to another function.
	veritysetup $SETUP_ARGS \| tail -n +2 \| process_verity
	}

	# make "dateless" symlink for the hash so the wks can find it.
	verity_hash() {
	cd ${IMGDEPLOYDIR}
	ln -sf ${IMAGE_NAME}.${DM_VERITY_IMAGE_TYPE}.vhash \
	${IMAGE_BASENAME}-${MACHINE}.${DM_VERITY_IMAGE_TYPE}.vhash
	}

	VERITY_TYPES = " \
	ext2.verity ext3.verity ext4.verity \
	btrfs.verity \
	erofs.verity erofs-lz4.verity erofs-lz4hc.verity \
	squashfs.verity squashfs-xz.verity squashfs-lzo.verity squashfs-lz4.verity squashfs-zst.verity \
	"
	IMAGE_TYPES += "${VERITY_TYPES}"
	CONVERSIONTYPES += "verity"
	CONVERSION_CMD:verity = "verity_setup ${type}"
	CONVERSION_DEPENDS_verity = "cryptsetup-native"
	IMAGE_CMD:vhash = "verity_hash"

	python __anonymous() {
	verity_image = d.getVar('DM_VERITY_IMAGE')
	verity_type = d.getVar('DM_VERITY_IMAGE_TYPE')
	verity_hash = d.getVar('DM_VERITY_SEPARATE_HASH')
	image_fstypes = d.getVar('IMAGE_FSTYPES')
	pn = d.getVar('PN')

	if not verity_image or not verity_type:
	bb.warn('dm-verity-img class inherited but not used')
	return

	if verity_image != pn:
	return # This doesn't concern this image

	if len(verity_type.split()) != 1:
	bb.fatal('DM_VERITY_IMAGE_TYPE must contain exactly one type')

	d.appendVar('IMAGE_FSTYPES', ' %s.verity' % verity_type)
	if verity_hash == "1":
	d.appendVar('IMAGE_FSTYPES', ' vhash')

	# If we're using wic: we'll have to use partition images and not the rootfs
	# source plugin so add the appropriate dependency.
	if 'wic' in image_fstypes:
	dep = ' %s:do_image_%s' % (pn, verity_type.replace("-", "_"))
	d.appendVarFlag('do_image_wic', 'depends', dep)
	}