new file mode 100644
@@ -0,0 +1,17 @@
+FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
+
+SRC_URI += "file://uefi-secureboot.cfg"
+
+inherit sbsign
+
+DEPENDS += 'python3-pyopenssl-native'
+
+do_compile:prepend() {
+ export CRYPTOGRAPHY_OPENSSL_NO_LEGACY=1
+
+ "${S}"/tools/efivar.py set -i "${S}"/ubootefi.var -n pk -d "${SBSIGN_KEYS_DIR}"/PK.esl -t file
+ "${S}"/tools/efivar.py set -i "${S}"/ubootefi.var -n kek -d "${SBSIGN_KEYS_DIR}"/KEK.esl -t file
+ "${S}"/tools/efivar.py set -i "${S}"/ubootefi.var -n db -d "${SBSIGN_KEYS_DIR}"/db.esl -t file
+ "${S}"/tools/efivar.py set -i "${S}"/ubootefi.var -n dbx -d "${SBSIGN_KEYS_DIR}"/dbx.esl -t file
+ "${S}"/tools/efivar.py print -i "${S}"/ubootefi.var
+}
new file mode 100644
@@ -0,0 +1,10 @@
+CONFIG_CMD_BOOTMENU=y
+CONFIG_USE_BOOTCOMMAND=y
+CONFIG_BOOTCOMMAND="bootmenu"
+CONFIG_USE_PREBOOT=y
+CONFIG_EFI_VAR_BUF_SIZE=65536
+CONFIG_FIT_SIGNATURE=y
+CONFIG_EFI_SECURE_BOOT=y
+CONFIG_EFI_VARIABLES_PRESEED=y
+CONFIG_PREBOOT="setenv bootmenu_0 UEFI Boot Manager=bootefi bootmgr; setenv bootmenu_1 UEFI Maintenance Menu=eficonfig"
+CONFIG_PREBOOT_DEFINED=y
\ No newline at end of file
@@ -5,6 +5,7 @@ MACHINE_U-BOOT_REQUIRE:corstone1000 = "u-boot-corstone1000.inc"
MACHINE_U-BOOT_REQUIRE:fvp-base = "u-boot-fvp-base.inc"
MACHINE_U-BOOT_REQUIRE:juno = "u-boot-juno.inc"
MACHINE_U-BOOT_REQUIRE:tc = "u-boot-tc.inc"
+MACHINE_U-BOOT_REQUIRE += "${@bb.utils.contains('MACHINE_FEATURES', 'uefi-secureboot', 'u-boot-uefi-secureboot.inc', '', d)}"
require ${MACHINE_U-BOOT_REQUIRE}
@@ -7,4 +7,4 @@ part /boot --source bootimg-efi --sourceparams="loader=${EFI_PROVIDER}" --label
part / --source rootfs --fstype=ext4 --label root --align 1024 --use-uuid --exclude-path boot/
-bootloader --ptable gpt --timeout=1 --append="${GRUB_LINUX_APPEND}"
+bootloader --ptable gpt --timeout=5
new file mode 100644
@@ -0,0 +1,31 @@
+# Sign binaries for UEFI Secure Boot
+#
+# Usage in recipes:
+#
+# Set binary to sign per recipe:
+# SBSIGN_TARGET_BINARY = "${B}/binary_to_sign"
+#
+# Then call do_sbsign() in correct stage of the build
+# do_compile:append() {
+# do_sbsign
+# }
+
+DEPENDS += 'gen-sbkeys'
+DEPENDS += "sbsigntool-native"
+
+SBSIGN_KEY = "${SBSIGN_KEYS_DIR}/db.key"
+SBSIGN_CERT = "${SBSIGN_KEYS_DIR}/db.crt"
+SBSIGN_TARGET_BINARY ?= "binary_to_sign"
+
+# Not adding as task since recipes may need to sign binaries at different
+# stages. Instead they can call this function when needed by calling this function
+do_sbsign() {
+ bbnote "Signing ${PN} binary ${SBSIGN_TARGET_BINARY} with ${SBSIGN_KEY} and ${SBSIGN_CERT}"
+ ${STAGING_BINDIR_NATIVE}/sbsign \
+ --key "${SBSIGN_KEY}" \
+ --cert "${SBSIGN_CERT}" \
+ --output "${SBSIGN_TARGET_BINARY}.signed" \
+ "${SBSIGN_TARGET_BINARY}"
+ cp "${SBSIGN_TARGET_BINARY}" "${SBSIGN_TARGET_BINARY}.unsigned"
+ cp "${SBSIGN_TARGET_BINARY}.signed" "${SBSIGN_TARGET_BINARY}"
+}
\ No newline at end of file
new file mode 100644
@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: MIT
+
+SUMMARY = "Generate Signing UEFI keys for Secure Boot"
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
+
+DEPENDS += "bash-native"
+DEPENDS += "coreutils-native"
+DEPENDS += "efitools-native"
+DEPENDS += "openssl-native"
+
+SRC_URI = "file://gen_sbkeys.sh"
+
+UNPACKDIR = "${S}"
+
+do_patch[noexec] = "1"
+do_compile[noexec] = "1"
+do_configure[noexec] = "1"
+do_install[nostamp] = "1"
+
+python do_install() {
+ keys_dir = d.getVar('SBSIGN_KEYS_DIR', True)
+
+ keys_to_check = [
+ keys_dir + "/PK.esl",
+ keys_dir + "/KEK.esl",
+ keys_dir + "/db.esl",
+ keys_dir + "/dbx.esl",
+ keys_dir + "/db.key",
+ keys_dir + "/db.crt",
+ ]
+
+ missing_keys = [f for f in keys_to_check if not os.path.exists(f)]
+
+ if not missing_keys:
+ bb.debug(2, "All UEFI keys found in '%s' to sign binaries'" % keys_dir)
+ return
+
+ gen_sbkeys = d.getVar('UNPACKDIR', True) + "/gen_sbkeys.sh"
+
+ import subprocess
+ bb.debug(2, "Calling '%s' to generate UEFI keys in path: '%s'" % (gen_sbkeys, keys_dir))
+ cmd = "%s %s" % (gen_sbkeys, keys_dir)
+ subprocess.Popen(cmd, shell=True)
+}
+
+FILES:${PN} += "${SBSIGN_KEYS_DIR}/db.key"
+FILES:${PN} += "${SBSIGN_KEYS_DIR}/db.crt"
new file mode 100755
@@ -0,0 +1,52 @@
+#!/bin/bash
+#
+# SPDX-License-Identifier: MIT
+#
+#
+# Set up UEFI Secure Boot keys. Generate keys and certificates, convert them
+# into EFI Signature Lists, and sign them. By managing these keys, you can
+# control what is considered trusted on your system.
+
+set -eux
+
+KEYS_PATH=${1:-./}
+SUBJECT="/CN=OpenEmbedded/"
+
+# The number used is just a GUID random number that has not special meaning.
+# GUID (Globally Unique Identifier) is associated with the signature list. GUIDs
+# in this context are used to uniquely identify the owner or the purpose of the
+# keys within the EFI environment. This GUID can be used to distinguish
+# different lists or purposes within the UEFI firmware settings
+GUID="11111111-2222-3333-4444-123456789abc"
+
+if [ ! -d "${KEYS_PATH}" ]; then
+ mkdir -p "${KEYS_PATH}"
+fi
+
+if [ -f "${KEYS_PATH}"/PK.crt ]; then
+ exit 0
+fi
+
+# Platform Key (PK): The root key in Secure Boot, which authorizes changes to
+# the KEK
+openssl req -x509 -sha256 -newkey rsa:2048 -subj "${SUBJECT}" \
+ -keyout "${KEYS_PATH}"/PK.key -out "${KEYS_PATH}"/PK.crt \
+ -nodes -days 3650
+cert-to-efi-sig-list -g ${GUID} \
+ "${KEYS_PATH}"/PK.crt "${KEYS_PATH}"/PK.esl
+sign-efi-sig-list -c "${KEYS_PATH}"/PK.crt -k "${KEYS_PATH}"/PK.key \
+ "${KEYS_PATH}"/PK "${KEYS_PATH}"/PK.esl "${KEYS_PATH}"/PK.auth
+
+# Key Exchange Key (KEK): Allows for updates to the db and dbx lists
+#
+# db and dbx: Control lists for allowed and disallowed executable files and
+# drivers
+for key in KEK db dbx; do
+ openssl req -x509 -sha256 -newkey rsa:2048 -subj "${SUBJECT}" \
+ -keyout "${KEYS_PATH}"/${key}.key -out "${KEYS_PATH}"/${key}.crt \
+ -nodes -days 3650
+ cert-to-efi-sig-list -g ${GUID} \
+ "${KEYS_PATH}"/${key}.crt "${KEYS_PATH}"/${key}.esl
+ sign-efi-sig-list -c "${KEYS_PATH}"/PK.crt -k "${KEYS_PATH}"/PK.key \
+ "${KEYS_PATH}"/${key} "${KEYS_PATH}"/${key}.esl "${KEYS_PATH}"/${key}.auth
+done
new file mode 100644
@@ -0,0 +1,7 @@
+inherit sbsign
+
+SBSIGN_TARGET_BINARY = "${B}/src/boot/efi/systemd-boot${EFI_ARCH}.efi"
+
+do_compile:append() {
+ do_sbsign
+}
new file mode 100644
@@ -0,0 +1 @@
+require ${@bb.utils.contains('MACHINE_FEATURES', 'uefi-secureboot', 'systemd-boot-uefi-secureboot.inc', '', d)}
\ No newline at end of file
new file mode 100644
@@ -0,0 +1 @@
+PACKAGECONFIG:append = " efi"
new file mode 100644
@@ -0,0 +1 @@
+require ${@bb.utils.contains('MACHINE_FEATURES', 'efi', 'systemd-efi.inc', '', d)}
@@ -25,3 +25,5 @@ SRC_URI:append:qemuarm = " \
FFA_TRANSPORT_INCLUDE = "${@bb.utils.contains('MACHINE_FEATURES', 'arm-ffa', 'arm-ffa-transport.inc', '' , d)}"
require ${FFA_TRANSPORT_INCLUDE}
+
+require ${@bb.utils.contains('MACHINE_FEATURES', 'uefi-secureboot', 'linux-yocto-uefi-secureboot.inc', '', d)}
\ No newline at end of file
new file mode 100644
@@ -0,0 +1,14 @@
+KERNEL_FEATURES += "cfg/efi-ext.scc"
+
+inherit sbsign
+
+# shell variable set inside do_compile task
+SBSIGN_TARGET_BINARY = "$KERNEL_IMAGE"
+
+do_compile:append() {
+ KERNEL_IMAGE=$(find ${B} -name ${KERNEL_IMAGETYPE} -print -quit)
+ do_sbsign
+}
+
+RRECOMMENDS:${PN} += "kernel-module-efivarfs"
+RRECOMMENDS:${PN} += "kernel-module-efivars"
In the target, Secure Boot starts from the firmware (u-boot), adds the signing keys, and verifies the bootloader (systemd-boot) and kernel (Linux). The gen-sbkeys recipe generates keys in the host during build time. If keys are found, it will skip the keys generation. As long as the keys are the same, it will guarantee build reproducibility. sbsign bbclass is used to sign the binaries. sbsign is the name of the tool used to sign these binaries. Hence the name of this class to sbsign and variables with SBSIGN prefix. Signed-off-by: Javier Tia <javier.tia@linaro.org> --- .../u-boot/u-boot-uefi-secureboot.inc | 17 ++++++ .../u-boot/u-boot/uefi-secureboot.cfg | 10 ++++ .../recipes-bsp/u-boot/u-boot_%.bbappend | 1 + meta-arm-bsp/wic/efi-disk-no-swap.wks.in | 2 +- meta-arm/classes/sbsign.bbclass | 31 +++++++++++ meta-arm/recipes-bsp/uefi/gen-sbkeys.bb | 48 +++++++++++++++++ .../recipes-bsp/uefi/gen-sbkeys/gen_sbkeys.sh | 52 +++++++++++++++++++ .../systemd/systemd-boot-uefi-secureboot.inc | 7 +++ .../systemd/systemd-boot_%.bbappend | 1 + meta-arm/recipes-core/systemd/systemd-efi.inc | 1 + .../recipes-core/systemd/systemd_%.bbappend | 1 + .../linux/linux-yocto%.bbappend | 2 + .../linux/linux-yocto-uefi-secureboot.inc | 14 +++++ 13 files changed, 186 insertions(+), 1 deletion(-) create mode 100644 meta-arm-bsp/recipes-bsp/u-boot/u-boot-uefi-secureboot.inc create mode 100644 meta-arm-bsp/recipes-bsp/u-boot/u-boot/uefi-secureboot.cfg create mode 100644 meta-arm/classes/sbsign.bbclass create mode 100644 meta-arm/recipes-bsp/uefi/gen-sbkeys.bb create mode 100755 meta-arm/recipes-bsp/uefi/gen-sbkeys/gen_sbkeys.sh create mode 100644 meta-arm/recipes-core/systemd/systemd-boot-uefi-secureboot.inc create mode 100644 meta-arm/recipes-core/systemd/systemd-boot_%.bbappend create mode 100644 meta-arm/recipes-core/systemd/systemd-efi.inc create mode 100644 meta-arm/recipes-core/systemd/systemd_%.bbappend create mode 100644 meta-arm/recipes-kernel/linux/linux-yocto-uefi-secureboot.inc