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@ -28,7 +28,6 @@ import (
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"github.com/fxamacker/cbor/v2"
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"github.com/google/go-attestation/attest"
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"github.com/google/go-tpm/tpm2"
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"github.com/ryboe/q"
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"go.step.sm/crypto/jose"
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"go.step.sm/crypto/keyutil"
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@ -448,7 +447,6 @@ func deviceAttest01Validate(ctx context.Context, ch *Challenge, db DB, jwk *jose
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data, err := doTPMAttestationFormat(ctx, ch, db, jwk, &att)
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if err != nil {
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var acmeError *Error
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q.Q("att error: %w", err)
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if errors.As(err, &acmeError) {
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if acmeError.Status == 500 {
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return acmeError
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@ -494,6 +492,10 @@ func keyAuthDigest(jwk *jose.JSONWebKey, token string) ([]byte, error) {
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return digest[:], err
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}
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var (
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oidSubjectAlternativeName = asn1.ObjectIdentifier{2, 5, 29, 17}
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)
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type tpmAttestationData struct {
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Certificate *x509.Certificate
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VerifiedChains [][]*x509.Certificate
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@ -554,17 +556,10 @@ func doTPMAttestationFormat(ctx context.Context, ch *Challenge, db DB, jwk *jose
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unhandledCriticalExtensions := leaf.UnhandledCriticalExtensions[:0]
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for _, extOID := range leaf.UnhandledCriticalExtensions {
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switch {
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case extOID.Equal(asn1.ObjectIdentifier{2, 5, 29, 17}): // Subject Alternative Name
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// TODO(hs): decide when the processed extension is "OK"; permanent-identifier/hardware-module-name
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for _, e := range leaf.Extensions {
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if e.Id.Equal(extOID) {
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// TODO(hs): validate this is in fact a valid PermanentIdentifier/HardwareModuleName
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q.Q(e)
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}
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}
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continue
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case extOID.Equal(oidSubjectAlternativeName):
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// allow Subject Alternative Names, including PermanentIdentifier, HardwareModuleName, TPM attributes, etc
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default:
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// OIDs that are not in the switch remain unhandled
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// OIDs that are not in the switch with explicitly allowed OIDs remain unhandled
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unhandledCriticalExtensions = append(unhandledCriticalExtensions, extOID)
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}
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}
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@ -573,7 +568,7 @@ func doTPMAttestationFormat(ctx context.Context, ch *Challenge, db DB, jwk *jose
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roots, ok := prov.GetAttestationRoots()
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if !ok {
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return nil, NewErrorISE("error getting tpm attestation root CAs")
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return nil, NewErrorISE("failed getting tpm attestation root CAs")
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}
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verifiedChains, err := leaf.Verify(x509.VerifyOptions{
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@ -620,19 +615,22 @@ func doTPMAttestationFormat(ctx context.Context, ch *Challenge, db DB, jwk *jose
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return nil, NewError(ErrorBadAttestationStatementType, "invalid certInfo in attestation statement")
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}
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// recreate the generated key certification parameter values and verify
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// the attested key using the public key of the AK.
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certificationParameters := &attest.CertificationParameters{
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Public: pubArea,
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CreateSignature: sig,
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CreateAttestation: certInfo,
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Public: pubArea, // the public key that was attested
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CreateAttestation: certInfo, // the attested properties of the key
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CreateSignature: sig, // signature over the attested properties
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}
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verifyOpts := attest.VerifyOpts{
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Public: leaf.PublicKey, // signature created by the AK that attested the key
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Public: leaf.PublicKey, // public key of the AK that attested the key
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Hash: hash,
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}
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if err = certificationParameters.Verify(verifyOpts); err != nil {
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return nil, WrapError(ErrorBadAttestationStatementType, err, "invalid certification parameters")
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}
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// decode the "certInfo" data
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tpmCertInfo, err := tpm2.DecodeAttestationData(certInfo)
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if err != nil {
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return nil, WrapError(ErrorBadAttestationStatementType, err, "failed decoding attestation data")
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@ -649,6 +647,7 @@ func doTPMAttestationFormat(ctx context.Context, ch *Challenge, db DB, jwk *jose
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return nil, NewError(ErrorBadAttestationStatementType, "key authorization doesn not match")
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}
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// decode the (attested) public key and determine its fingerprint
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pub, err := tpm2.DecodePublic(pubArea)
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if err != nil {
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return nil, WrapError(ErrorBadAttestationStatementType, err, "failed decoding pubArea")
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Herman Slatman
1 year ago