chore(ci): Ensure kernels are signed (#268)

.github/workflows/reusable-build.yml

@@ -232,6 +232,25 @@ jobs:
           oci: false
           extra-args: |
             --target=${{ matrix.image_target }}
+  
+      - name: Check Secureboot
+        shell: bash
+        run: |
+          set -x
+          if [[ ! $(command -v sbverify) || ! $(command -v curl) || ! $(command -v openssl) ]]; then
+            sudo apt update
+            sudo apt install sbsigntool curl openssl
+          fi
+          podman run -d --rm --name ${{env.IMAGE_NAME}}-$(echo "${{ steps.generate-tags.outputs.alias_tags }}" | cut -d " " -f 1) "${{ env.IMAGE_NAME }}":$(echo "${{ steps.generate-tags.outputs.alias_tags }}" | cut -d " " -f 1) sleep 1000
+          podman cp ${{env.IMAGE_NAME}}-$(echo "${{ steps.generate-tags.outputs.alias_tags }}" | cut -d " " -f 1):/usr/lib/modules/${{ env.KERNEL_VERSION }}/vmlinuz .
+          podman rm -f ${{env.IMAGE_NAME}}-$(echo "${{ steps.generate-tags.outputs.alias_tags }}" | cut -d " " -f 1)
+          sbverify --list vmlinuz
+          curl --retry 3 -Lo kernel-sign.der https://github.com/ublue-os/kernel-cache/raw/main/certs/public_key.der
+          curl --retry 3 -Lo akmods.der https://github.com/ublue-os/kernel-cache/raw/main/certs/public_key_2.der
+          openssl x509 -in kernel-sign.der -out kernel-sign.crt
+          openssl x509 -in akmods.der -out akmods.crt
+          sbverify --cert kernel-sign.crt vmlinuz || exit 1
+          sbverify --cert akmods.crt vmlinuz || exit 1
 
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