[4/8] initdata-processor: support insecure platforms

initdata-processor/main.go

@@ -5,15 +5,22 @@ package main
 
 import (
 	"bytes"
+	"context"
+	"errors"
 	"fmt"
 	"io"
 	"io/fs"
 	"log"
+	"net"
+	"net/http"
 	"os"
 	"path/filepath"
+	"slices"
+	"strings"
 
 	"github.com/edgelesssys/contrast/initdata-processor/policy"
 	"github.com/edgelesssys/contrast/initdata-processor/validator"
+	"github.com/edgelesssys/contrast/internal/attestation/insecure"
 	"github.com/edgelesssys/contrast/internal/initdata"
 )
 
@@ -22,14 +29,20 @@ const (
 	insecureConfigPath = "/run/insecure-cfg"
 )
 
-var version = "0.0.0-dev"
+var (
+	version           = "0.0.0-dev"
+	kernelCmdlinePath = "/proc/cmdline"
+)
 
 // We always exit with status code 0 so that the Kata agent can start and propagate errors to
 // the runtime.
 func main() {
 	log.Printf("Contrast initdata-processor %s", version)
 	log.Print("Report issues at https://github.com/edgelesssys/contrast/issues")
 
+	var hostdata []byte
+	var insecurePlatform bool
+
 	// Handle initdata.
 	if err := os.MkdirAll(measuredConfigPath, 0o755); err != nil {
 		failf("Could not create directory %q: %v", measuredConfigPath, err)
@@ -45,7 +58,8 @@ func main() {
 		failf("%s is not an initdata device: %v", device, err)
 		return
 	}
-	if err := handleInitdata(doc); err != nil {
+	hostdata, insecurePlatform, err = handleInitdata(doc)
+	if err != nil {
 		failf("handling initdata: %v", err)
 		return
 	}
@@ -59,44 +73,107 @@ func main() {
 	device, err = checkDeviceAvailability("imagepuller")
 	if err != nil {
 		log.Println("No imagepuller auth config found, only unauthenticated pulls will be available")
-		return
-	}
-	doc, err = initdata.FromDevice(device, "imgpullr")
-	if err != nil {
-		failf("%s is not an imagepuller config device: %v", device, err)
-		return
+	} else {
+		doc, err = initdata.FromDevice(device, "imgpullr")
+		if err != nil {
+			failf("%s is not an imagepuller config device: %v", device, err)
+			return
+		}
+		if err := handleImagepullerAuthConfig(doc); err != nil {
+			failf("handling imagepuller auth config: %v", err)
+			return
+		}
+		log.Printf("Processed imagepuller auth config from %q ", device)
 	}
-	if err := handleImagepullerAuthConfig(doc); err != nil {
-		failf("handling imagepuller auth config: %v", err)
-		return
+
+	// Signal systemd that initdata processing is complete.
+	sdNotifyReady()
+
+	// On insecure platforms, serve the hostdata digest via HTTP so that
+	// the insecure aTLS issuer (running inside containers) can fetch it.
+	if insecurePlatform {
+		log.Printf("Starting insecure hostdata server on %s", insecure.HostdataAddr)
+		if err := serveHostdata(hostdata); err != nil {
+			log.Printf("Hostdata server error: %v", err)
+		}
 	}
-	log.Printf("Processed imagepuller auth config from %q ", device)
 }
 
-func handleInitdata(doc initdata.Raw) error {
+func handleInitdata(doc initdata.Raw) (hostdata []byte, insecurePlatform bool, retErr error) {
 	digest, err := doc.Digest()
 	if err != nil {
-		return fmt.Errorf("initdata validation failed: %w", err)
+		return nil, false, fmt.Errorf("computing initdata digest: %w", err)
 	}
-	validator, err := validator.New()
+
+	allowInsecure, err := allowInsecureAttestation()
 	if err != nil {
-		return fmt.Errorf("creating validator: %w", err)
+		return nil, false, err
 	}
-	if err := validator.ValidateDigest(digest); err != nil {
-		return fmt.Errorf("validating initdata digest: %w", err)
+
+	v, verr := validator.New()
+	if errors.Is(verr, validator.ErrNoPlatform) {
+		if !allowInsecure {
+			return nil, false, fmt.Errorf("no TEE platform detected and insecure attestation is not allowed")
+		}
+		log.Print("WARNING: No TEE platform detected, skipping initdata digest validation. This is expected on insecure platforms.")
+	} else if verr != nil {
+		return nil, false, fmt.Errorf("creating validator: %w", verr)
+	} else if err := v.ValidateDigest(digest); err != nil {
+		return nil, false, fmt.Errorf("validating initdata digest: %w", err)
 	}
+
 	data, err := doc.Parse()
 	if err != nil {
-		return fmt.Errorf("parsing initdata: %w", err)
+		return nil, false, fmt.Errorf("parsing initdata: %w", err)
 	}
 	for name, content := range data.Data {
 		name = filepath.Clean(name)
 		path := filepath.Join(measuredConfigPath, name)
 		if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
-			return fmt.Errorf("writing file %q: %w", path, err)
+			return nil, false, fmt.Errorf("writing file %q: %w", path, err)
 		}
 	}
-	return nil
+	return digest, allowInsecure, nil
+}
+
+func allowInsecureAttestation() (bool, error) {
+	cmdline, err := os.ReadFile(kernelCmdlinePath)
+	if err != nil {
+		return false, fmt.Errorf("reading kernel command line: %w", err)
+	}
+	if slices.Contains(strings.Fields(string(cmdline)), "contrast.allow_insecure_attestation=1") {
+		return true, nil
+	}
+	return false, nil
+}
+
+// serveHostdata starts an HTTP server that serves the hostdata digest.
+func serveHostdata(hostdata []byte) error {
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /hostdata", func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "application/octet-stream")
+		if _, err := w.Write(hostdata); err != nil {
+			log.Printf("hostdata write error: %v", err)
+		}
+	})
+	return http.ListenAndServe(insecure.HostdataAddr, mux)
+}
+
+// sdNotifyReady signals systemd that the service is ready.
+func sdNotifyReady() {
+	addr := os.Getenv("NOTIFY_SOCKET")
+	if addr == "" {
+		return
+	}
+	conn, err := (&net.Dialer{}).DialContext(context.Background(), "unixgram", addr)
+	if err != nil {
+		log.Printf("sd_notify: dial: %v", err)
+		return
+	}
+	defer conn.Close()
+	if _, err := conn.Write([]byte("READY=1")); err != nil {
+		log.Printf("sd_notify: write: %v", err)
+	}
 }
 
 func handleImagepullerAuthConfig(doc initdata.Raw) error {

initdata-processor/main_test.go

@@ -0,0 +1,47 @@
+// Copyright 2026 Edgeless Systems GmbH
+// SPDX-License-Identifier: BUSL-1.1
+
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAllowInsecureAttestation(t *testing.T) {
+	oldKernelCmdlinePath := kernelCmdlinePath
+	t.Cleanup(func() { kernelCmdlinePath = oldKernelCmdlinePath })
+
+	testCases := map[string]struct {
+		cmdline string
+		want    bool
+	}{
+		"absent": {
+			cmdline: "console=hvc0",
+			want:    false,
+		},
+		"disabled": {
+			cmdline: "console=hvc0 contrast.allow_insecure_attestation=0",
+			want:    false,
+		},
+		"enabled": {
+			cmdline: "console=hvc0 contrast.allow_insecure_attestation=1 quiet",
+			want:    true,
+		},
+	}
+
+	for name, tc := range testCases {
+		t.Run(name, func(t *testing.T) {
+			kernelCmdlinePath = filepath.Join(t.TempDir(), "cmdline")
+			require.NoError(t, os.WriteFile(kernelCmdlinePath, []byte(tc.cmdline), 0o644))
+
+			got, err := allowInsecureAttestation()
+			require.NoError(t, err)
+			assert.Equal(t, tc.want, got)
+		})
+	}
+}

initdata-processor/validator/validator.go

@@ -29,7 +29,7 @@ func New() (*Validator, error) {
 	if terr == nil {
 		return &Validator{&tdxDigestGetter{tqp}}, nil
 	}
-	return nil, fmt.Errorf("%w:\nTDX:%w\nSNP:%w", errBadPlatform, terr, serr)
+	return nil, fmt.Errorf("%w:\nTDX:%w\nSNP:%w", ErrNoPlatform, terr, serr)
 }
 
 // ValidateDigest compares the given digest with either MRCONFIGID or HOSTDATA, and returns an error if they don't match.
@@ -85,7 +85,9 @@ func getTDXQuoteProvider() (tdxclient.QuoteProvider, error) {
 }
 
 var (
-	errBadPlatform          = errors.New("no digest getter available for current platform")
+	// ErrNoPlatform is returned by New when no TEE platform is available for digest validation.
+	ErrNoPlatform = errors.New("no digest getter available for current platform")
+
 	errUnexpectedDigestSize = errors.New("unexpected digest size")
 	errDigestMismatch       = errors.New("digests don't match")
 )

nodeinstaller/internal/kataconfig/config.go

@@ -6,6 +6,7 @@ package kataconfig
 import (
 	"fmt"
 	"path/filepath"
+	"strings"
 
 	"github.com/edgelesssys/contrast/internal/platforms"
 	"github.com/pelletier/go-toml/v2"
@@ -75,6 +76,9 @@ func KataRuntimeConfig(
 
 	// Replace the kernel params entirely (and don't append) since that's
 	// also what we do when calculating the launch measurement.
+	if platforms.IsInsecure(platform) {
+		qemuExtraKernelParams = strings.TrimSpace(qemuExtraKernelParams + " contrast.allow_insecure_attestation=1")
+	}
 	config.Hypervisor["qemu"]["kernel_params"] = qemuExtraKernelParams
 	// Conditionally enable debug mode.
 	config.Hypervisor["qemu"]["enable_debug"] = debug

nodeinstaller/internal/kataconfig/testdata/runtime-go/expected-configuration-qemu-insecure-gpu.toml

@@ -44,7 +44,7 @@ image = '/share/kata-containers.img'
 indep_iothreads = 0
 initrd = '/share/kata-initrd.zst'
 kernel = '/share/kata-kernel'
-kernel_params = ''
+kernel_params = 'contrast.allow_insecure_attestation=1'
 kernel_verity_params = ''
 machine_accelerators = ''
 machine_type = 'q35'

nodeinstaller/internal/kataconfig/testdata/runtime-go/expected-configuration-qemu-insecure.toml

@@ -43,7 +43,7 @@ image = '/share/kata-containers.img'
 indep_iothreads = 0
 initrd = '/share/kata-initrd.zst'
 kernel = '/share/kata-kernel'
-kernel_params = ''
+kernel_params = 'contrast.allow_insecure_attestation=1'
 kernel_verity_params = ''
 machine_accelerators = ''
 machine_type = 'q35'

nodeinstaller/internal/kataconfig/testdata/runtime-rs/expected-configuration-qemu-insecure-gpu.toml

@@ -41,7 +41,7 @@ guest_memory_dump_path = ''
 image = '/share/kata-containers.img'
 initrd = '/share/kata-initrd.zst'
 kernel = '/share/kata-kernel'
-kernel_params = ''
+kernel_params = 'contrast.allow_insecure_attestation=1'
 kernel_verity_params = ''
 machine_accelerators = ''
 machine_type = 'q35'

nodeinstaller/internal/kataconfig/testdata/runtime-rs/expected-configuration-qemu-insecure.toml

@@ -41,7 +41,7 @@ guest_memory_dump_path = ''
 image = '/share/kata-containers.img'
 initrd = '/share/kata-initrd.zst'
 kernel = '/share/kata-kernel'
-kernel_params = ''
+kernel_params = 'contrast.allow_insecure_attestation=1'
 kernel_verity_params = ''
 machine_accelerators = ''
 machine_type = 'q35'

packages/by-name/initdata-processor/package.nix

@@ -48,6 +48,8 @@ buildGoModule (finalAttrs: {
         (path.append root "go.sum")
         (path.append root "initdata-processor/go.mod")
         (path.append root "initdata-processor/go.sum")
+        (fileset.fileFilter (file: hasSuffix ".go" file.name) (path.append root "internal/attestation"))
+        (fileset.fileFilter (file: hasSuffix ".go" file.name) (path.append root "internal/oid"))
         (fileset.fileFilter (file: hasSuffix ".go" file.name) (path.append root "internal/initdata"))
         (fileset.fileFilter (file: hasSuffix ".go" file.name) (path.append root "initdata-processor"))
       ];

packages/nixos/kata.nix

@@ -57,7 +57,12 @@ in
       wants = [ "initdata.target" ];
 
       serviceConfig = {
-        Type = "oneshot";
+        # notify: the process signals READY=1 when initdata processing is
+        # complete, allowing initdata.target to be reached. On insecure
+        # platforms the process stays alive to serve hostdata via HTTP;
+        # on CC platforms it exits after signaling.
+        Type = "notify";
+        NotifyAccess = "main";
         RemainAfterExit = "yes";
         ExecStart = lib.getExe pkgs.contrastPkgs.initdata-processor;
       };