constellation/internal/attestation/aws/issuer.go

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/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
package aws
import (
"context"
"encoding/json"
"errors"
"io"
"log"
"github.com/aws/aws-sdk-go-v2/feature/ec2/imds"
"github.com/edgelesssys/constellation/v2/internal/attestation/vtpm"
"github.com/edgelesssys/constellation/v2/internal/oid"
"github.com/google/go-tpm-tools/client"
tpmclient "github.com/google/go-tpm-tools/client"
)
// Issuer for AWS TPM attestation.
type Issuer struct {
oid.AWS
*vtpm.Issuer
}
func NewIssuer() *Issuer {
return &Issuer{
Issuer: vtpm.NewIssuer(
vtpm.OpenVTPM,
getAttestationKey,
getInstanceInfo(imds.New(imds.Options{})),
),
}
}
// getAttestationKey returns a new attestation key.
func getAttestationKey(tpm io.ReadWriter) (*tpmclient.Key, error) {
tpmAk, err := client.AttestationKeyRSA(tpm)
if err != nil {
log.Fatalf("error creating RSA Endorsement key!")
return nil, err
}
return tpmAk, nil
}
// getInstanceInfo returns information about the current instance using the aws Metadata SDK.
// The returned bytes will be written into the attestation document.
func getInstanceInfo(client awsMetaData) func(tpm io.ReadWriteCloser) ([]byte, error) {
return func(io.ReadWriteCloser) ([]byte, error) {
ec2InstanceIdentityOutput, err := client.GetInstanceIdentityDocument(context.Background(), &imds.GetInstanceIdentityDocumentInput{})
if err != nil {
return nil, errors.New("unable to fetch instance identity document")
}
return json.Marshal(ec2InstanceIdentityOutput.InstanceIdentityDocument)
}
}
type awsMetaData interface {
GetInstanceIdentityDocument(context.Context, *imds.GetInstanceIdentityDocumentInput, ...func(*imds.Options)) (*imds.GetInstanceIdentityDocumentOutput, error)
}