attesters: add NVIDIA GPU evidence plugin

attesters/Makefile

@@ -3,6 +3,7 @@
 
 SUBDIR := tsm
 SUBDIR += mocktsm
+SUBDIR += gpu
 
 clean: ; $(RM) -rf ./bin
 

attesters/gpu/Makefile

@@ -0,0 +1,10 @@
+# Copyright 2026 Contributors to the Veraison project.
+# SPDX-License-Identifier: Apache-2.0
+.DEFAULT_GOAL := test
+
+GOPKG := github.com/veraison/ratsd/attesters/gpu
+SRCS := $(wildcard *.go)
+
+SUBDIR += plugin
+
+include ../../mk/subdir.mk

attesters/gpu/gpu.go

@@ -0,0 +1,214 @@
+// Copyright 2026 Contributors to the Veraison project.
+// SPDX-License-Identifier: Apache-2.0
+package gpu
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/NVIDIA/go-nvml/pkg/nvml"
+	nvgpu "github.com/confidentsecurity/go-nvtrust/pkg/gonvtrust/gpu"
+	"github.com/veraison/ratsd/proto/compositor"
+	"github.com/veraison/ratsd/tokens"
+)
+
+const (
+	ApplicationvndVeraisonNvGpuEvidenceJSON = tokens.GPUEvidenceMediaTypeJSON
+	ApplicationvndVeraisonNvGpuEvidenceCBOR = tokens.GPUEvidenceMediaTypeCBOR
+	gpuNonceSize                            = nvml.CC_GPU_CEC_NONCE_SIZE
+)
+
+var (
+	sid = &compositor.SubAttesterID{
+		Name:    "nv-gpu-evidence",
+		Version: "1.0.0",
+	}
+
+	supportedFormats = []*compositor.Format{
+		{
+			ContentType: ApplicationvndVeraisonNvGpuEvidenceJSON,
+			NonceSize:   gpuNonceSize,
+		},
+		{
+			ContentType: ApplicationvndVeraisonNvGpuEvidenceCBOR,
+			NonceSize:   gpuNonceSize,
+		},
+	}
+
+	statusSucceeded = &compositor.Status{Result: true, Error: ""}
+)
+
+type evidenceCollector interface {
+	CollectEvidence(nonce []byte) ([]nvgpu.GPUDevice, error)
+	Shutdown() error
+}
+
+type collectorFactory func() (evidenceCollector, error)
+
+type GPUPlugin struct {
+	newCollector collectorFactory
+}
+
+func NewPlugin() *GPUPlugin {
+	return &GPUPlugin{newCollector: defaultCollectorFactory}
+}
+
+func defaultCollectorFactory() (evidenceCollector, error) {
+	return nvgpu.NewNvmlGPUAdmin(nil)
+}
+
+func getEvidenceError(e error) *compositor.EvidenceOut {
+	return &compositor.EvidenceOut{
+		Status: &compositor.Status{
+			Result: false,
+			Error:  e.Error(),
+		},
+	}
+}
+
+func (g *GPUPlugin) GetOptions() *compositor.OptionsOut {
+	return &compositor.OptionsOut{
+		Options: []*compositor.Option{},
+		Status:  statusSucceeded,
+	}
+}
+
+func (g *GPUPlugin) GetSubAttesterID() *compositor.SubAttesterIDOut {
+	return &compositor.SubAttesterIDOut{
+		SubAttesterID: sid,
+		Status:        statusSucceeded,
+	}
+}
+
+func (g *GPUPlugin) GetSupportedFormats() *compositor.SupportedFormatsOut {
+	collector, err := g.newCollector()
+	if err != nil {
+		return &compositor.SupportedFormatsOut{
+			Status: &compositor.Status{
+				Result: false,
+				Error:  fmt.Sprintf("GPU evidence collection is not available: %s", err.Error()),
+			},
+		}
+	}
+
+	if err := collector.Shutdown(); err != nil {
+		return &compositor.SupportedFormatsOut{
+			Status: &compositor.Status{
+				Result: false,
+				Error:  fmt.Sprintf("GPU evidence collection is not available: %s", err.Error()),
+			},
+		}
+	}
+
+	return &compositor.SupportedFormatsOut{
+		Status:  statusSucceeded,
+		Formats: supportedFormats,
+	}
+}
+
+func (g *GPUPlugin) GetEvidence(in *compositor.EvidenceIn) *compositor.EvidenceOut {
+	if uint32(len(in.Nonce)) != gpuNonceSize {
+		errMsg := fmt.Errorf(
+			"nonce size of the GPU attester should be %d, got %d",
+			gpuNonceSize, uint32(len(in.Nonce)),
+		)
+		return getEvidenceError(errMsg)
+	}
+
+	if err := validateOptions(in.Options); err != nil {
+		return getEvidenceError(err)
+	}
+
+	if !supportsFormat(in.ContentType) {
+		return getEvidenceError(fmt.Errorf("no supported format in gpu plugin matches the requested format"))
+	}
+
+	collector, err := g.newCollector()
+	if err != nil {
+		return getEvidenceError(fmt.Errorf("failed to initialize GPU evidence collector: %v", err))
+	}
+
+	devices, collectErr := collector.CollectEvidence(in.Nonce)
+	shutdownErr := collector.Shutdown()
+
+	if collectErr != nil {
+		return getEvidenceError(fmt.Errorf("failed to collect GPU evidence: %v", collectErr))
+	}
+	if shutdownErr != nil {
+		return getEvidenceError(fmt.Errorf("failed to shutdown GPU evidence collector: %v", shutdownErr))
+	}
+
+	encodedEvidence, err := encodeEvidence(in.ContentType, in.Nonce, devices)
+	if err != nil {
+		return getEvidenceError(err)
+	}
+
+	return &compositor.EvidenceOut{
+		Status:   statusSucceeded,
+		Evidence: encodedEvidence,
+	}
+}
+
+func supportsFormat(contentType string) bool {
+	for _, format := range supportedFormats {
+		if format.ContentType == contentType {
+			return true
+		}
+	}
+
+	return false
+}
+
+func validateOptions(options []byte) error {
+	if len(options) == 0 || string(options) == "null" {
+		return nil
+	}
+
+	var parsed map[string]json.RawMessage
+	if err := json.Unmarshal(options, &parsed); err != nil {
+		return fmt.Errorf("failed to parse %s: %v", options, err)
+	}
+
+	if len(parsed) > 0 {
+		return fmt.Errorf("gpu attester does not support options")
+	}
+
+	return nil
+}
+
+func encodeEvidence(contentType string, nonce []byte, devices []nvgpu.GPUDevice) ([]byte, error) {
+	token := &tokens.GPUEvidence{
+		Devices: make([]tokens.GPUDeviceEvidence, len(devices)),
+	}
+
+	for i, device := range devices {
+		certChain, err := device.Certificate().EncodeBase64()
+		if err != nil {
+			return nil, fmt.Errorf("failed to encode GPU certificate chain for device %d: %v", i, err)
+		}
+
+		token.Devices[i] = tokens.GPUDeviceEvidence{
+			Nonce:             nonce,
+			Arch:              device.Arch(),
+			AttestationReport: device.AttestationReport(),
+			CertificateChain:  certChain,
+		}
+	}
+
+	switch contentType {
+	case ApplicationvndVeraisonNvGpuEvidenceJSON:
+		encodedEvidence, err := token.ToJSON()
+		if err != nil {
+			return nil, fmt.Errorf("failed to JSON encode GPU evidence: %v", err)
+		}
+		return encodedEvidence, nil
+	case ApplicationvndVeraisonNvGpuEvidenceCBOR:
+		encodedEvidence, err := token.ToCBOR()
+		if err != nil {
+			return nil, fmt.Errorf("failed to CBOR encode GPU evidence: %v", err)
+		}
+		return encodedEvidence, nil
+	default:
+		return nil, fmt.Errorf("no supported format in gpu plugin matches the requested format")
+	}
+}