mirror of
https://github.com/raspberrypi/rpi-eeprom.git
synced 2026-01-21 06:13:33 +08:00
c6b8de409d
If used in a build environment that sets SOURCE_DATE_EPOCH, we should honour that in order to generate reproducible binaries. See https://reproducible-builds.org/specs/source-date-epoch/ .
152 lines
4.1 KiB
Bash
Executable File
152 lines
4.1 KiB
Bash
Executable File
#!/bin/sh
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# Helper script to generate .sig files for use with the Raspberry Pi bootloader.
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# This has been implemented in a separate script in order to have avoid having
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# a hard dependency on OpenSSL.
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set -e
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OPENSSL=${OPENSSL:-openssl}
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die() {
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echo "$@" >&2
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exit 1
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}
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TMP_DIR=""
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cleanup() {
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if [ -d "${TMP_DIR}" ]; then
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rm -rf "${TMP_DIR}"
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fi
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}
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checkDependencies() {
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if ! command -v sha256sum > /dev/null; then
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die "sha256sum not found. Try installing the coreutilities package."
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fi
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if [ -n "${KEY}" ] || [ "${VERIFY}" = 1 ]; then
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if ! command -v openssl > /dev/null; then
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die "openssl not found. Try installing the openssl package."
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fi
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if ! command -v xxd > /dev/null; then
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die "xxd not found. Try installing the xxd package."
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fi
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fi
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}
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usage() {
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cat <<EOF
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rpi-eeprom-digest [-k RSA_KEY] -i IMAGE -o OUTPUT
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Tool to generate .sig files containing the SHA256 digest and optional
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RSA signature. Typically this tool is used by rpi-eeprom-update to
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generate a hash to guard against file-system corruption for EEPROM updates
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OR for signing OS images (boot.img) for secure-boot.
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This tool CANNOT be used directly to sign an bootloader EEPROM image
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for secure-boot because the signed data is bootloader configuration file
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rather than the entire flash image.
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To create signed bootloader images please see
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https://github.com/raspberrypi/usbboot/tree/master/secure-boot-recovery/README.md
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Options:
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-i The source image e.g. boot.img
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-o The name of the digest/signature file.
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-k Optional RSA private key.
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RSA signing
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If a private key in PEM format is supplied then the RSA signature of the
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sha256 digest is included in the .sig file. Currently, the bootloader only
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supports sha256 digests signed with a 2048bit RSA key.
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The bootloader only verifies RSA signatures in signed boot mode
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and only for the EEPROM config file and the signed image.
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Examples:
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# Generate the normal sha256 hash to guard against file-system corruption
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rpi-eeprom-digest -i pieeprom.bin -o pieeprom.sig
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rpi-eeprom-digest -i vl805.bin -o vl805.sig
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# Generate a signed OS ramdisk image for secure-boot
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rpi-eeprom-digest -k private.pem -i boot.img -o boot.sig
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# Generate RSA signature for the EEPROM config file
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# As used by update-pieeprom.sh in usbboot/secure-boot-recovery
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rpi-eeprom-digest -k private.pem -i bootconf.txt -o bootconf.sig
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# To verify the signature of an existing .sig file using the public key.
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# N.B The key file must be the PUBLIC key in PEM format.
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rpi-eeprom-digest -k public.pem -i boot.bin -v boot.sig
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EOF
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exit 0
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}
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writeSig() {
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TMP_DIR=$(mktemp -d)
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SIG_TMP="${TMP_DIR}/tmp.sig"
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sha256sum "${IMAGE}" | awk '{print $1}' > "${OUTPUT}"
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# Include the update-timestamp
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if [ -n "${SOURCE_DATE_EPOCH}" ] ; then
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echo "ts: ${SOURCE_DATE_EPOCH}" >> "${OUTPUT}"
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else
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echo "ts: $(date -u +%s)" >> "${OUTPUT}"
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fi
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if [ -n "${KEY}" ]; then
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[ -f "${KEY}" ] || die "RSA private \"${KEY}\" not found"
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"${OPENSSL}" dgst -sign "${KEY}" -keyform PEM -sha256 -out "${SIG_TMP}" "${IMAGE}"
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echo "rsa2048: $(xxd -c 4096 -p < "${SIG_TMP}")" >> "${OUTPUT}"
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fi
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}
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verifySig() {
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TMP_DIR=$(mktemp -d)
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sig_file="${1}"
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[ -f "${sig_file}" ] || die "Signature file ${sig_file} not found"
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sig_hex="$(grep rsa2048 "${sig_file}" | cut -f 2 -d ' ')"
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[ -n "${sig_hex}" ] || die "No RSA signature in ${sig_file}"
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echo ${sig_hex} | xxd -c 4096 -p -r > "${TMP_DIR}/sig.bin"
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"${OPENSSL}" dgst -verify "${KEY}" -signature "${TMP_DIR}/sig.bin" "${IMAGE}" || die "${IMAGE} not verified"
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}
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OUTPUT=""
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VERIFY=0
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while getopts i:k:ho:v: option; do
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case "${option}" in
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i) IMAGE="${OPTARG}"
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;;
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k) KEY="${OPTARG}"
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;;
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o) OUTPUT="${OPTARG}"
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;;
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v) SIGNATURE="${OPTARG}"
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VERIFY=1
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;;
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h) usage
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;;
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*) echo "Unknown argument \"${option}\""
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usage
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;;
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esac
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done
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trap cleanup EXIT
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checkDependencies
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[ -n "${IMAGE}" ] || usage
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[ -f "${IMAGE}" ] || die "Source image \"${IMAGE}\" not found"
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if [ "${VERIFY}" = 1 ]; then
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verifySig "${SIGNATURE}"
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else
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[ -n "${OUTPUT}" ] || usage
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writeSig
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fi
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