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https://github.com/edgelesssys/constellation.git
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cdc91b50bc
With the introduction of SNP-based attestation on AWS some of the information in the report (MAAToken) is not applicable to all attestation reports anymore. Thus, make verify cmd CSP-agnostic and move CSP-specific logic to internal/verify. Also make internal/attestation/snp CSP aware.
104 lines
2.5 KiB
Go
104 lines
2.5 KiB
Go
/*
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Copyright (c) Edgeless Systems GmbH
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SPDX-License-Identifier: AGPL-3.0-only
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*/
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package snp
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import (
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"context"
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"encoding/json"
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"fmt"
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"io"
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"github.com/edgelesssys/constellation/v2/internal/attestation"
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"github.com/edgelesssys/constellation/v2/internal/attestation/snp"
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"github.com/edgelesssys/constellation/v2/internal/attestation/variant"
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"github.com/edgelesssys/constellation/v2/internal/attestation/vtpm"
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"github.com/edgelesssys/go-azguestattestation/maa"
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tpmclient "github.com/google/go-tpm-tools/client"
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)
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const tpmAkIdx = 0x81000003
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// Issuer for Azure TPM attestation.
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type Issuer struct {
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variant.AzureSEVSNP
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*vtpm.Issuer
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imds imdsAPI
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maa maaTokenCreator
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}
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// NewIssuer initializes a new Azure Issuer.
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func NewIssuer(log attestation.Logger) *Issuer {
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i := &Issuer{
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imds: newIMDSClient(),
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maa: newMAAClient(),
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}
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i.Issuer = vtpm.NewIssuer(
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vtpm.OpenVTPM,
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getAttestationKey,
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i.getInstanceInfo,
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log,
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)
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return i
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}
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func (i *Issuer) getInstanceInfo(ctx context.Context, tpm io.ReadWriteCloser, userData []byte) ([]byte, error) {
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params, err := i.maa.newParameters(ctx, userData, tpm)
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if err != nil {
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return nil, fmt.Errorf("getting system parameters: %w", err)
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}
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var maaToken string
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maaURL, err := i.imds.getMAAURL(ctx)
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if err != nil {
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return nil, fmt.Errorf("retrieving MAA URL from IMDS API: %w", err)
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}
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if maaURL != "" {
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maaToken, err = i.maa.createToken(ctx, tpm, maaURL, userData, params)
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if err != nil {
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return nil, fmt.Errorf("creating MAA token: %w", err)
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}
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}
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instanceInfo := snp.InstanceInfo{
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ReportSigner: params.VcekCert,
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CertChain: params.VcekChain,
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AttestationReport: params.SNPReport,
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Azure: &snp.AzureInstanceInfo{
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RuntimeData: params.RuntimeData,
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MAAToken: maaToken,
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},
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}
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statement, err := json.Marshal(instanceInfo)
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if err != nil {
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return nil, fmt.Errorf("marshalling AzureInstanceInfo: %w", err)
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}
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return statement, nil
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}
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// getAttestationKey reads the attestation key put into the TPM during early boot.
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func getAttestationKey(tpm io.ReadWriter) (*tpmclient.Key, error) {
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ak, err := tpmclient.LoadCachedKey(tpm, tpmAkIdx, tpmclient.NullSession{})
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if err != nil {
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return nil, fmt.Errorf("reading HCL attestation key from TPM: %w", err)
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}
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return ak, nil
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}
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type imdsAPI interface {
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getMAAURL(ctx context.Context) (string, error)
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}
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type maaTokenCreator interface {
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newParameters(context.Context, []byte, io.ReadWriter) (maa.Parameters, error)
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createToken(context.Context, io.ReadWriter, string, []byte, maa.Parameters) (string, error)
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}
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