kmsv2: validate encrypt response at DEK generation time

Prior to this change, we wait until the DEK is used to perform an
encryption before validating the response.  This means that the
plugin could report healthy but all TransformToStorage calls would
fail.  Now we correctly cause the plugin to become unhealthy and do
not attempt to use the newly generated DEK.

Signed-off-by: Monis Khan <mok@microsoft.com>

staging/src/k8s.io/apiserver/pkg/server/options/encryptionconfig/config_test.go

@@ -81,9 +81,10 @@ func (t *testEnvelopeService) Encrypt(data []byte) ([]byte, error) {
 // testKMSv2EnvelopeService is a mock kmsv2 envelope service which can be used to simulate remote Envelope v2 services
 // for testing of the envelope transformer with other transformers.
 type testKMSv2EnvelopeService struct {
-	err          error
-	keyID        string
-	encryptCalls int
+	err                error
+	keyID              string
+	encryptCalls       int
+	encryptAnnotations map[string][]byte
 }
 
 func (t *testKMSv2EnvelopeService) Decrypt(ctx context.Context, uid string, req *kmsservice.DecryptRequest) ([]byte, error) {
@@ -99,8 +100,9 @@ func (t *testKMSv2EnvelopeService) Encrypt(ctx context.Context, uid string, data
 		return nil, t.err
 	}
 	return &kmsservice.EncryptResponse{
-		Ciphertext: []byte(base64.StdEncoding.EncodeToString(data)),
-		KeyID:      t.keyID,
+		Ciphertext:  []byte(base64.StdEncoding.EncodeToString(data)),
+		KeyID:       t.keyID,
+		Annotations: t.encryptAnnotations,
 	}, nil
 }
 
@@ -123,17 +125,17 @@ func newMockErrorEnvelopeService(endpoint string, timeout time.Duration) (envelo
 
 // The factory method to create mock envelope kmsv2 service.
 func newMockEnvelopeKMSv2Service(ctx context.Context, endpoint, providerName string, timeout time.Duration) (kmsservice.Service, error) {
-	return &testKMSv2EnvelopeService{nil, "1", 0}, nil
+	return &testKMSv2EnvelopeService{nil, "1", 0, nil}, nil
 }
 
 // The factory method to create mock envelope kmsv2 service which always returns error.
 func newMockErrorEnvelopeKMSv2Service(endpoint string, timeout time.Duration) (kmsservice.Service, error) {
-	return &testKMSv2EnvelopeService{errors.New("test"), "1", 0}, nil
+	return &testKMSv2EnvelopeService{errors.New("test"), "1", 0, nil}, nil
 }
 
 // The factory method to create mock envelope kmsv2 service that always returns invalid keyID.
 func newMockInvalidKeyIDEnvelopeKMSv2Service(ctx context.Context, endpoint string, timeout time.Duration, keyID string) (kmsservice.Service, error) {
-	return &testKMSv2EnvelopeService{nil, keyID, 0}, nil
+	return &testKMSv2EnvelopeService{nil, keyID, 0, nil}, nil
 }
 
 func TestLegacyConfig(t *testing.T) {
@@ -1758,6 +1760,39 @@ func Test_kmsv2PluginProbe_rotateDEKOnKeyIDChange(t *testing.T) {
 				`errState=<nil>, errGen=failed to encrypt DEK, error: broken, statusKeyID="5", ` +
 				`encryptKeyID="", stateKeyID="4", expirationTimestamp=` + now.Add(7*time.Minute).Format(time.RFC3339),
 		},
+		{
+			name:             "invalid service response, no previous state",
+			service:          &testKMSv2EnvelopeService{keyID: "1", encryptAnnotations: map[string][]byte{"panda": nil}},
+			state:            envelopekmsv2.State{},
+			statusKeyID:      "1",
+			wantState:        envelopekmsv2.State{},
+			wantEncryptCalls: 1,
+			wantLogs: []string{
+				`"encrypting content using envelope service" uid="panda"`,
+			},
+			wantErr: `failed to rotate DEK uid="panda", ` +
+				`errState=got unexpected nil transformer, errGen=failed to validate annotations: annotations: Invalid value: "panda": ` +
+				`should be a domain with at least two segments separated by dots, statusKeyID="1", ` +
+				`encryptKeyID="", stateKeyID="", expirationTimestamp=` + (time.Time{}).Format(time.RFC3339),
+		},
+		{
+			name:        "invalid service response, with previous state",
+			service:     &testKMSv2EnvelopeService{keyID: "3", encryptAnnotations: map[string][]byte{"panda": nil}},
+			state:       validState("2", now),
+			statusKeyID: "3",
+			wantState: envelopekmsv2.State{
+				KeyID:               "2",
+				ExpirationTimestamp: now,
+			},
+			wantEncryptCalls: 1,
+			wantLogs: []string{
+				`"encrypting content using envelope service" uid="panda"`,
+			},
+			wantErr: `failed to rotate DEK uid="panda", ` +
+				`errState=<nil>, errGen=failed to validate annotations: annotations: Invalid value: "panda": ` +
+				`should be a domain with at least two segments separated by dots, statusKeyID="3", ` +
+				`encryptKeyID="", stateKeyID="2", expirationTimestamp=` + now.Format(time.RFC3339),
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

staging/src/k8s.io/apiserver/pkg/storage/value/encrypt/envelope/kmsv2/envelope.go

@@ -278,6 +278,15 @@ func GenerateTransformer(ctx context.Context, uid string, envelopeService kmsser
 		return nil, nil, nil, fmt.Errorf("failed to encrypt DEK, error: %w", err)
 	}
 
+	if err := validateEncryptedObject(&kmstypes.EncryptedObject{
+		KeyID:         resp.KeyID,
+		EncryptedDEK:  resp.Ciphertext,
+		EncryptedData: []byte{0}, // any non-empty value to pass validation
+		Annotations:   resp.Annotations,
+	}); err != nil {
+		return nil, nil, nil, err
+	}
+
 	cacheKey, err := generateCacheKey(resp.Ciphertext, resp.KeyID, resp.Annotations)
 	if err != nil {
 		return nil, nil, nil, err