On Thu, 7 Sept 2023 at 01:29, Alejandro Hernandez Samaniego
<a...@linux.microsoft.com> wrote:
>
>
> On 9/2/23 00:53, Richard Purdie wrote:
> > On Fri, 2023-09-01 at 23:32 +0000, Michelle Lin wrote:
> >> Currently, there is not a class to support the building of unified kernel
> >> images. Adding a uki.bbclass to support the creation of UKIs. This class
> >> calls
> >> the systemd Ukify tool, which will combine the kernel/initrd/stub
> >> components to
> >> build the UKI. To sign the UKI (i.e. SecureBoot, TPM PCR signing), the
> >> keys/cert
> >> files are to be specified in a separate configuration file, and the path
> >> to the
> >> file is passed to the Ukify tool. UKIs are supported by UEFI and can
> >> improve
> >> security through predicted TPM PCR states, and reduce the build burden due
> >> to
> >> its single PE binary format.
> >>
> >> Signed-off-by: Michelle Lin <michelle.lint...@gmail.com>
> >> ---
> >> meta/classes/uki.bbclass | 140 +++++++++++++++++++++++
> >> meta/recipes-core/systemd/systemd_254.bb | 23 ++++
> >> 2 files changed, 163 insertions(+)
> >> create mode 100644 meta/classes/uki.bbclass
> >>
> >> diff --git a/meta/classes/uki.bbclass b/meta/classes/uki.bbclass
> >> new file mode 100644
> >> index 0000000000..2eff387c75
> >> --- /dev/null
> >> +++ b/meta/classes/uki.bbclass
> >> @@ -0,0 +1,140 @@
> >> +#
> >> +# Unified kernel image (UKI) class
> >> +#
> >> +#
> >> +# This bbclass is designed to repack an Overlake image as a UKI, to be
> >> booted on a qemuarm64 with SecureBoot
> >> +# signing and embedded with TPM PCR measurements.
> >> +#
> >> +# The UKI is composed by:
> >> +# - an UEFI stub
> >> +# The linux kernel can generate a UEFI stub, however the one from
> >> systemd-boot can fetch
> >> +# the command line from a separate section of the EFI application,
> >> avoiding the need to
> >> +# rebuild the kernel.
> >> +# - the kernel
> >> +# - an initramfs
> >> +# - other metadata (e.g. PCR measurements)
> >> +#
> >> +#
> >> +#
> >> +
> >> +# List build time dependencies
> >> +DEPENDS += "systemd-native \
> >> + sbsigntool-native \
> >> + virtual/${TARGET_PREFIX}binutils \
> >> + "
> >> +
> >> +REQUIRED_DISTRO_FEATURES += "usrmerge systemd"
> >> +
> >> +inherit features_check
> >> +require ../conf/image-uefi.conf
> >> +
> >> +INITRD_IMAGE ?= "core-image-minimal-initramfs"
> >> +
> >> +INITRD_LIVE ?= "${@ ('${DEPLOY_DIR_IMAGE}/' + d.getVar('INITRD_IMAGE') +
> >> '-${MACHINE}.cpio.gz') if d.getVar('INITRD_IMAGE') else ''}"
> >> +
> >> +UKI_CONFIG_FILE ?= "${WORKDIR}/core-image-minimal-uki.conf"
> >> +UKI_FILENAME ?= "${@ 'UKI.signed.efi' if d.getVar('UKI_CONFIG_FILE') else
> >> 'UKI.unsigned.efi'}"
> >> +
> >> +do_uki[depends] += " \
> >> + systemd-boot:do_deploy \
> >> + virtual/kernel:do_deploy \
> >> + "
> >> +
> >> +# INITRD_IMAGE is added to INITRD_LIVE, which we use to create our
> >> initrd, so depend on it if it is set
> >> +# So we want to generate the initrd image if INITRD_IMAGE exists
> >> +do_uki[depends] += "${@ '${INITRD_IMAGE}:do_image_complete' if
> >> d.getVar('INITRD_IMAGE') else ''}"
> >> +
> >> +# ensure that the build directory is empty everytime we generate a
> >> newly-created uki
> >> +do_uki[cleandirs] = "${B}"
> >> +# influence the build directory at the start of the builds
> >> +do_uki[dirs] = "${B}"
> >> +
> >> +# we want to allow specifying files in SRC_URI, such as for signing the
> >> UKI
> >> +python () {
> >> + d.delVarFlag("do_fetch","noexec")
> >> + d.delVarFlag("do_unpack","noexec")
> >> +}
> >> +
> >> +# main task
> >> +python do_uki() {
> >> + import glob
> >> + import subprocess
> >> +
> >> + # Construct the ukify command
> >> + ukify_cmd = ("ukify build")
> >> +
> >> + # Handle the creation of an initrd image by reading and concatenating
> >> multiple cpio files.
> >> + # If the INITRD_LIVE variable is defined and not empty, it opens the
> >> necessary files, reads their contents,
> >> + # and constructs a list.
> >> + if d.getVar('INITRD_LIVE'):
> >> + initrd_list = ""
> >> + for cpio in d.getVar('INITRD_LIVE').split():
> >> + # get a list of initrds
> >> + initrd_list += cpio + ' '
> >> +
> >> + ukify_cmd += " --initrd=%s" % initrd_list
> >> + else:
> >> + bb.fatal("ERROR - Required argument: INITRD")
> >> +
> >> + deploy_dir_image = d.getVar('DEPLOY_DIR_IMAGE')
> >> +
> >> + # Kernel
> >> + if d.getVar('KERNEL_IMAGETYPE'):
> >> + kernel = "%s/%s" % (deploy_dir_image,
> >> d.getVar('KERNEL_IMAGETYPE'))
> >> + kernel_version = d.getVar('KERNEL_VERSION')
> >> + if not os.path.exists(kernel):
> >> + bb.fatal(f"ERROR: cannot find {kernel}.")
> >> +
> >> + ukify_cmd += " --linux=%s --uname %s" % (kernel, kernel_version)
> >> + else:
> >> + bb.fatal("ERROR - Required argument: KERNEL")
> >> +
> >> + # Architecture
> >> + target_arch = d.getVar('EFI_ARCH')
> >> + ukify_cmd += " --efi-arch %s" % target_arch
> >> +
> >> + # Stub
> >> + stub = "%s/linux%s.efi.stub" % (deploy_dir_image, target_arch)
> >> + if not os.path.exists(stub):
> >> + bb.fatal(f"ERROR: cannot find {stub}.")
> >> + ukify_cmd += " --stub %s" % stub
> >> +
> >> + # Add option for dtb
> >> + if d.getVar('KERNEL_DEVICETREE'):
> >> + first_dtb = d.getVar('KERNEL_DEVICETREE').split()[0]
> >> + dtb_path = "%s/%s" % (deploy_dir_image, first_dtb)
> >> +
> >> + if not os.path.exists(dtb_path):
> >> + bb.fatal(f"ERROR: cannot find {dtb_path}.")
> >> +
> >> + ukify_cmd += " --devicetree %s" % dtb_path
> >> +
> >> + # Add option to pass a config file to sign the UKI.
> >> + if os.path.exists(d.getVar('UKI_CONFIG_FILE')):
> >> + ukify_cmd += " --config=%s" % d.getVar('UKI_CONFIG_FILE')
> >> + ukify_cmd += " --tools=%s%s/lib/systemd/tools" %
> >> (d.getVar("RECIPE_SYSROOT_NATIVE"), d.getVar("prefix"))
> >> + bb.note("Pulling keys from config file")
> >> + else:
> >> + bb.note("Generating unsigned UKI")
> >> +
> >> + # Custom UKI name
> >> + output = " --output=%s" % d.getVar('UKI_FILENAME')
> >> + ukify_cmd += " %s" % output
> >> +
> >> + # Set env to determine where bitbake should look for dynamic libraries
> >> + env = os.environ.copy() # get the env variables
> >> + env['LD_LIBRARY_PATH'] =
> >> d.expand("${RECIPE_SYSROOT_NATIVE}/usr/lib/systemd:${LD_LIBRARY_PATH}")
> >> +
> >> + # Run the ukify command
> >> + subprocess.check_call(ukify_cmd, env=env, shell=True)
> >> +}
> >> +
> >> +inherit deploy
> >> +
> >> +do_deploy () {
> >> + # Copy generated UKI into DEPLOYDIR
> >> + install ${B}/${UKI_FILENAME} ${DEPLOYDIR}
> >> +}
> >> +
> >> +addtask uki before do_deploy do_image after do_rootfs
> >> +addtask deploy before do_build after do_compile
> >> \ No newline at end of file
> >> diff --git a/meta/recipes-core/systemd/systemd_254.bb
> >> b/meta/recipes-core/systemd/systemd_254.bb
> >> index 8d5cf13095..65f132abb8 100644
> >> --- a/meta/recipes-core/systemd/systemd_254.bb
> >> +++ b/meta/recipes-core/systemd/systemd_254.bb
> >> @@ -6,6 +6,9 @@ PE = "1"
> >>
> >> DEPENDS = "intltool-native gperf-native libcap util-linux
> >> python3-jinja2-native"
> >>
> >> +# The Ukify tool requires this module
> >> +DEPENDS:append:class-native = " python3-pefile-native"
> > Do we need to add this to OE-Core? I think this will cause current
> > builds to fail?
>
>
> I think you are right, there are some dependencies from this that are
> not present in OE-core, this probably belongs in a different layer, at
> least for the time being.
I think that ukify is useful in OE-core. Having it in another layer
would mean that we can not use it from the BSP layer.
As the ukify is usable even without sbsign and pesign, I think we can
do either of the following things:
- Mark sbsign and pesign as recomendations instead of dependencies
- Add PACAKGECONFIG for the signing support. If it is not enabled,
replace sbsign and pesign support with the error message.
--
With best wishes
Dmitry
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