constellation/internal/attestation/gcp/issuer.go
Otto Bittner 8f21972aec
attestation: add awsSEVSNP as new variant (#1900)
* variant: move into internal/attestation
* attesation: move aws attesation into subfolder nitrotpm
* config: add aws-sev-snp variant
* cli: add tf option to enable AWS SNP

For now the implementations in aws/nitrotpm and aws/snp
are identical. They both contain the aws/nitrotpm impl.
A separate commit will add the actual attestation logic.
2023-06-09 15:41:02 +02:00

88 lines
2.2 KiB
Go

/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
package gcp
import (
"context"
"encoding/json"
"errors"
"io"
"cloud.google.com/go/compute/metadata"
"github.com/edgelesssys/constellation/v2/internal/attestation"
"github.com/edgelesssys/constellation/v2/internal/attestation/variant"
"github.com/edgelesssys/constellation/v2/internal/attestation/vtpm"
tpmclient "github.com/google/go-tpm-tools/client"
"github.com/google/go-tpm-tools/proto/attest"
)
// Issuer for GCP confidential VM attestation.
type Issuer struct {
variant.GCPSEVES
*vtpm.Issuer
}
// NewIssuer initializes a new GCP Issuer.
func NewIssuer(log attestation.Logger) *Issuer {
return &Issuer{
Issuer: vtpm.NewIssuer(
vtpm.OpenVTPM,
tpmclient.GceAttestationKeyRSA,
getGCEInstanceInfo(metadataClient{}),
log,
),
}
}
// getGCEInstanceInfo fetches VM metadata used for attestation.
func getGCEInstanceInfo(client gcpMetadataClient) func(context.Context, io.ReadWriteCloser, []byte) ([]byte, error) {
// Ideally we would want to use the endorsement public key certificate
// However, this is not available on GCE instances
// Workaround: Provide ShieldedVM instance info
// The attestating party can request the VMs signing key using Google's API
return func(context.Context, io.ReadWriteCloser, []byte) ([]byte, error) {
projectID, err := client.projectID()
if err != nil {
return nil, errors.New("unable to fetch projectID")
}
zone, err := client.zone()
if err != nil {
return nil, errors.New("unable to fetch zone")
}
instanceName, err := client.instanceName()
if err != nil {
return nil, errors.New("unable to fetch instance name")
}
return json.Marshal(attest.GCEInstanceInfo{
Zone: zone,
ProjectId: projectID,
InstanceName: instanceName,
})
}
}
type gcpMetadataClient interface {
projectID() (string, error)
instanceName() (string, error)
zone() (string, error)
}
type metadataClient struct{}
func (c metadataClient) projectID() (string, error) {
return metadata.ProjectID()
}
func (c metadataClient) instanceName() (string, error) {
return metadata.InstanceName()
}
func (c metadataClient) zone() (string, error) {
return metadata.Zone()
}