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Refactor enforced/expected PCRs (#553)

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* Merge enforced and expected measurements

* Update measurement generation to new format

* Write expected measurements hex encoded by default

* Allow hex or base64 encoded expected measurements

* Allow hex or base64 encoded clusterID

* Allow security upgrades to warnOnly flag

* Upload signed measurements in JSON format

* Fetch measurements either from JSON or YAML

* Use yaml.v3 instead of yaml.v2

* Error on invalid enforced selection

* Add placeholder measurements to config

* Update e2e test to new measurement format

Signed-off-by: Daniel Weiße <dw@edgeless.systems>
This commit is contained in:
Daniel Weiße 2022-11-24 10:57:58 +01:00 • committed by GitHub
parent 8ce954e012
commit f8001efbc0
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GPG key ID: 4AEE18F83AFDEB23
46 changed files with 1180 additions and 801 deletions
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37
internal/attestation/vtpm/attestation.go
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@ -16,6 +16,7 @@ import (
"fmt"
"io"
"github.com/edgelesssys/constellation/v2/internal/attestation/measurements"
tpmClient "github.com/google/go-tpm-tools/client"
"github.com/google/go-tpm-tools/proto/attest"
tpmProto "github.com/google/go-tpm-tools/proto/tpm"
@ -144,8 +145,7 @@ func (i *Issuer) Issue(userData []byte, nonce []byte) ([]byte, error) {
// Validator handles validation of TPM based attestation.
type Validator struct {
expectedPCRs map[uint32][]byte
enforcedPCRs map[uint32]struct{}
expected measurements.M
getTrustedKey GetTPMTrustedAttestationPublicKey
validateCVM ValidateCVM
verifyUserData VerifyUserData
@ -154,18 +154,11 @@ type Validator struct {
}
// NewValidator returns a new Validator.
func NewValidator(expectedPCRs map[uint32][]byte, enforcedPCRs []uint32, getTrustedKey GetTPMTrustedAttestationPublicKey,
func NewValidator(expected measurements.M, getTrustedKey GetTPMTrustedAttestationPublicKey,
validateCVM ValidateCVM, verifyUserData VerifyUserData, log AttestationLogger,
) *Validator {
// Convert the enforced PCR list to a map for convenient and fast lookup
enforcedMap := make(map[uint32]struct{})
for _, pcr := range enforcedPCRs {
enforcedMap[pcr] = struct{}{}
}
return &Validator{
expectedPCRs: expectedPCRs,
enforcedPCRs: enforcedMap,
expected: expected,
getTrustedKey: getTrustedKey,
validateCVM: validateCVM,
verifyUserData: verifyUserData,
@ -212,9 +205,9 @@ func (v *Validator) Validate(attDocRaw []byte, nonce []byte) ([]byte, error) {
if err != nil {
return nil, err
}
for idx, pcr := range v.expectedPCRs {
if !bytes.Equal(pcr, attDoc.Attestation.Quotes[quoteIdx].Pcrs.Pcrs[idx]) {
if _, ok := v.enforcedPCRs[idx]; ok {
for idx, pcr := range v.expected {
if !bytes.Equal(pcr.Expected[:], attDoc.Attestation.Quotes[quoteIdx].Pcrs.Pcrs[idx]) {
if !pcr.WarnOnly {
return nil, fmt.Errorf("untrusted PCR value at PCR index %d", idx)
}
if v.log != nil {
@ -263,8 +256,8 @@ func VerifyPKCS1v15(pub crypto.PublicKey, hash crypto.Hash, hashed, sig []byte)
return rsa.VerifyPKCS1v15(key, hash, hashed, sig)
}
// GetSelectedPCRs returns a map of the selected PCR hashes.
func GetSelectedPCRs(open TPMOpenFunc, selection tpm2.PCRSelection) (map[uint32][]byte, error) {
// GetSelectedMeasurements returns a map of Measurments for the PCRs in selection.
func GetSelectedMeasurements(open TPMOpenFunc, selection tpm2.PCRSelection) (measurements.M, error) {
tpm, err := open()
if err != nil {
return nil, err
@ -276,5 +269,15 @@ func GetSelectedPCRs(open TPMOpenFunc, selection tpm2.PCRSelection) (map[uint32]
return nil, err
}
return pcrList.Pcrs, nil
m := make(measurements.M)
for i, pcr := range pcrList.Pcrs {
if len(pcr) != 32 {
return nil, fmt.Errorf("invalid measurement: invalid length: %d", len(pcr))
}
m[i] = measurements.Measurement{
Expected: *(*[32]byte)(pcr),
}
}
return m, nil
}