kernel-build.eclass: create multi-profile generic UKIs

systemd 257's ukify gains the ability to specify multiple "profiles" for an
UKI. This allows us to finally solve Bug 921195, which made it impossible to
simultaneously enforce verification of the kernel image (secureboot) and
enforce verification of the kernel modules (lockdown=integrity).

We also add a profile for "quiet splash", and change KERNEL_GENERIC_UKI_CMDLINE
to add another profile instead of overwriting the built-in kernel cmdline. To
support splash we add the plymouth and drm dracut modules but omit the drm
kernel modules that pull in huge firmware files. This will result in a less
visually smooth boot, but significantly decreases the size of the image.

Ukify can now also pass on the signing engine argument to systemd-measure
which enables the usage of pkcs11 uri's for measured boot.

Minimal version of systemd for USE=generic-uki is bumped to 257.

Closes: https://bugs.gentoo.org/921195
Signed-off-by: Nowa Ammerlaan <[email protected]>
Signed-off-by: Michał Górny <[email protected]>

eclass/kernel-build.eclass

@@ -1,4 +1,4 @@
-# Copyright 2020-2024 Gentoo Authors
+# Copyright 2020-2025 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 # @ECLASS: kernel-build.eclass
@@ -120,10 +120,14 @@ IUSE="+strip"
 # @ECLASS_VARIABLE: KERNEL_GENERIC_UKI_CMDLINE
 # @USER_VARIABLE
 # @DESCRIPTION:
-# If KERNEL_IUSE_GENERIC_UKI is set, this variable allows setting the
-# built-in kernel command line for the UKI. If unset, the default is
-# root=/dev/gpt-auto-root ro
-: "${KERNEL_GENERIC_UKI_CMDLINE:="root=/dev/gpt-auto-root ro"}"
+# If KERNEL_IUSE_GENERIC_UKI is set, and this variable is not
+# empty, then the contents are used as the first kernel cmdline
+# option of the multi-profile generic UKI. Supplementing the four
+# standard options of:
+# - root=/dev/gpt-auto-root ro
+# - root=/dev/gpt-auto-root ro quiet splash
+# - root=/dev/gpt-auto-root ro lockdown=integrity
+# - root=/dev/gpt-auto-root ro quiet splash lockdown=integrity
 
 if [[ ${KERNEL_IUSE_MODULES_SIGN} ]]; then
 	IUSE+=" modules-sign"
@@ -547,10 +551,10 @@ kernel-build_src_install() {
 
 			local dracut_modules=(
 				base bash btrfs cifs crypt crypt-gpg crypt-loop dbus dbus-daemon
-				dm dmraid dracut-systemd fido2 i18n fs-lib kernel-modules
+				dm dmraid dracut-systemd drm fido2 i18n fs-lib kernel-modules
 				kernel-network-modules kernel-modules-extra lunmask lvm nbd
 				mdraid modsign network network-manager nfs nvdimm nvmf pcsc
-				pkcs11 qemu qemu-net resume rngd rootfs-block shutdown
+				pkcs11 plymouth qemu qemu-net resume rngd rootfs-block shutdown
 				systemd systemd-ac-power systemd-ask-password systemd-initrd
 				systemd-integritysetup systemd-pcrphase systemd-sysusers
 				systemd-udevd systemd-veritysetup terminfo tpm2-tss udev-rules
@@ -576,37 +580,85 @@ kernel-build_src_install() {
 				--ro-mnt
 				--modules "${dracut_modules[*]}"
 				# Pulls in huge firmware files
-				--omit-drivers "nfp"
+				--omit-drivers "amdgpu i915 nfp nouveau nvidia xe"
 			)
 
 			# Tries to update ld cache
 			addpredict /etc/ld.so.cache~
 			dracut "${dracut_args[@]}" "${image%/*}/initrd" ||
 				die "Failed to generate initramfs"
 
+			# Note, we cannot use an associative array here because those are
+			# not ordered.
+			local profiles=()
+			local cmdlines=()
+
+			# If defined, make the user entry the first and default
+			if [[ -n ${KERNEL_GENERIC_UKI_CMDLINE} ]]; then
+				profiles+=(
+					$'TITLE=User specified at build time\nID=user'
+				)
+				cmdlines+=( "${KERNEL_GENERIC_UKI_CMDLINE}" )
+			fi
+
+			profiles+=(
+				$'TITLE=Default\nID=default'
+				$'TITLE=Default with splash\nID=splash'
+				$'TITLE=Default with lockdown\nID=lockdown'
+				$'TITLE=Default with splash and lockdown\nID=splash-lockdown'
+			)
+
+			cmdlines+=(
+				"root=/dev/gpt-auto-root ro"
+				"root=/dev/gpt-auto-root ro quiet splash"
+				"root=/dev/gpt-auto-root ro lockdown=integrity"
+				"root=/dev/gpt-auto-root ro quiet splash lockdown=integrity"
+			)
+
 			local ukify_args=(
 				--linux="${image}"
 				--initrd="${image%/*}/initrd"
-				--cmdline="${KERNEL_GENERIC_UKI_CMDLINE}"
 				--uname="${KV_FULL}"
 				--output="${image%/*}/uki.efi"
-			)
+				--profile="${profiles[0]}"
+				--cmdline="${cmdlines[0]}"
+			) # 0th profile is default
+
+			# Additional profiles have to be added with --join-profile
+			local i
+			for (( i=1; i<"${#profiles[@]}"; i++ )); do
+				ukify build \
+					--profile="${profiles[i]}" \
+					--cmdline="${cmdlines[i]}" \
+					--output="${T}/profile${i}.efi" ||
+						die "Failed to create profile ${i}"
+
+				ukify_args+=( --join-profile="${T}/profile${i}.efi" )
+			done
 
 			if [[ ${KERNEL_IUSE_MODULES_SIGN} ]] && use secureboot; then
+				openssl x509 \
+					-in "${SECUREBOOT_SIGN_CERT}" -inform PEM \
+					-out ${T}/pcrpkey.der -outform DER ||
+						die "Failed to convert certificate to DER format"
 				ukify_args+=(
-					--signtool=sbsign
 					--secureboot-private-key="${SECUREBOOT_SIGN_KEY}"
 					--secureboot-certificate="${SECUREBOOT_SIGN_CERT}"
+					--pcrpkey="${T}/pcrpkey.der"
+					--measure
 				)
 				if [[ ${SECUREBOOT_SIGN_KEY} == pkcs11:* ]]; then
 					ukify_args+=(
 						--signing-engine="pkcs11"
+						--pcr-private-key="${SECUREBOOT_SIGN_KEY}"
+						--pcr-public-key="${SECUREBOOT_SIGN_CERT}"
+						--phases="enter-initrd"
+						--pcr-private-key="${SECUREBOOT_SIGN_KEY}"
+						--pcr-public-key="${SECUREBOOT_SIGN_CERT}"
+						--phases="enter-initrd:leave-initrd enter-initrd:leave-initrd:sysinit enter-initrd:leave-initrd:sysinit:ready"
 					)
 				else
-					# Sytemd-measure does not currently support pkcs11
 					ukify_args+=(
-						--measure
-						--pcrpkey="${ED}${kernel_dir}/certs/signing_key.x509"
 						--pcr-private-key="${SECUREBOOT_SIGN_KEY}"
 						--phases="enter-initrd"
 						--pcr-private-key="${SECUREBOOT_SIGN_KEY}"
@@ -615,9 +667,7 @@ kernel-build_src_install() {
 				fi
 			fi
 
-			# systemd<255 does not install ukify in /usr/bin
-			PATH="${PATH}:${BROOT}/usr/lib/systemd:${BROOT}/lib/systemd" \
-				ukify build "${ukify_args[@]}" || die "Failed to generate UKI"
+			ukify build "${ukify_args[@]}" || die "Failed to generate UKI"
 
 			# Overwrite unnecessary image types to save space
 			> "${image}" || die