Enforce 10s timeout on Bootz HMAC challenge

MODULE.bazel

@@ -33,7 +33,7 @@ go_sdk.download(version = "1.26.4")
 
 go_deps = use_extension("@bazel_gazelle//:extensions.bzl", "go_deps")
 go_deps.from_file(go_mod = "//:go.mod")
-use_repo(go_deps, "com_github_coredhcp_coredhcp", "com_github_golang_glog", "com_github_google_go_cmp", "com_github_google_go_tpm", "com_github_insomniacslk_dhcp", "com_github_openconfig_monax", "org_golang_google_grpc", "org_golang_google_grpc_cmd_protoc_gen_go_grpc", "org_golang_google_protobuf", "org_golang_x_net", "org_mozilla_go_pkcs7")
+use_repo(go_deps, "com_github_coredhcp_coredhcp", "com_github_golang_glog", "com_github_google_go_cmp", "com_github_google_go_tpm", "com_github_insomniacslk_dhcp", "com_github_jonboulle_clockwork", "com_github_openconfig_monax", "org_golang_google_grpc", "org_golang_google_grpc_cmd_protoc_gen_go_grpc", "org_golang_google_protobuf", "org_golang_x_net", "org_mozilla_go_pkcs7")
 
 go_deps_dev = use_extension("@bazel_gazelle//:extensions.bzl", "go_deps", dev_dependency = True)
 

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/google/go-cmp v0.7.0
 	github.com/google/go-tpm v0.9.8
 	github.com/insomniacslk/dhcp v0.0.0-20260603135910-a415979eb11e
+	github.com/jonboulle/clockwork v0.5.0
 	github.com/openconfig/attestz v0.6.15
 	github.com/openconfig/gnsi v1.9.1
 	github.com/openconfig/monax v0.0.0-20260720151517-883500dc841b

go.sum

@@ -101,6 +101,8 @@ github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/insomniacslk/dhcp v0.0.0-20260603135910-a415979eb11e h1:7j1+lOuGBg7PQF1RxeVx0iP+/GpiAxSG/F+9t5JOS94=
 github.com/insomniacslk/dhcp v0.0.0-20260603135910-a415979eb11e/go.mod h1:qfvBmyDNp+/liLEYWRvqny/PEz9hGe2Dz833eXILSmo=
+github.com/jonboulle/clockwork v0.5.0 h1:Hyh9A8u51kptdkR+cqRpT1EebBwTn1oK9YfGYbdFz6I=
+github.com/jonboulle/clockwork v0.5.0/go.mod h1:3mZlmanh0g2NDKO5TWZVJAfofYk64M7XN3SzBPjZF60=
 github.com/josharian/native v1.1.0 h1:uuaP0hAbW7Y4l0ZRQ6C9zfb7Mg1mbFKry/xzDAfmtLA=
 github.com/josharian/native v1.1.0/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
 github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=

server/service/BUILD.bazel

@@ -27,6 +27,7 @@ go_library(
         "//proto:bootz",
         "@com_github_golang_glog//:glog",
         "@com_github_google_go_tpm//tpm2",
+        "@com_github_jonboulle_clockwork//:clockwork",
         "@openconfig_attestz//proto:tpm_enrollz_go",
         "@openconfig_attestz//service/biz:enrollz_biz",
         "@openconfig_attestz//service/biz:tpm20_utils",
@@ -50,6 +51,7 @@ go_test(
         "//proto:bootz",
         "@com_github_google_go_cmp//cmp",
         "@com_github_google_go_tpm//tpm2",
+        "@com_github_jonboulle_clockwork//:clockwork",
         "@openconfig_attestz//proto:tpm_enrollz_go",
         "@openconfig_attestz//service/biz:enrollz_biz",
         "@openconfig_attestz//service/biz:tpm20_utils",

server/service/service.go

@@ -34,9 +34,11 @@ import (
 	"net"
 	"slices"
 	"strings"
+	"time"
 
 	log "github.com/golang/glog"
 	"github.com/google/go-tpm/tpm2"
+	"github.com/jonboulle/clockwork"
 	"github.com/openconfig/attestz/service/biz"
 	ownercertificate "github.com/openconfig/bootz/common/owner_certificate"
 	"github.com/openconfig/bootz/common/signature"
@@ -62,6 +64,10 @@ const (
 	stateAttested
 )
 
+const (
+	hmacChallengeTimeout = 10 * time.Second
+)
+
 // ArtifactManager is an interface for providing security artifacts to the Bootz service. These artifacts are
 // associated either with the Bootz server itself (e.g. the Bootz server trust anchor keypair), or with a specific
 // control card in a chassis (e.g. Ownership Vouchers, EK/PPK keys).
@@ -95,27 +101,30 @@ type Service struct {
 	am    ArtifactManager
 	cm    ChassisManager
 	tpm20 biz.TPM20Utils
+	clock clockwork.Clock
 }
 
 type streamSession struct {
-	stream        bpb.Bootstrap_BootstrapStreamServer
-	currentState  int
-	chassis       *types.Chassis           // Store chassis info for later stages
-	status        *bpb.ReportStatusRequest // Store status for later stages
-	clientNonce   string                   // client nonce from bootstrap request
-	serverNonce   string                   // For TPM 2.0 with IDevID nonce challenge
-	hmacSensitive *tpm2.TPMTSensitive      // For TPM 2.0 without IDevID HMAC challenge
+	stream            bpb.Bootstrap_BootstrapStreamServer
+	currentState      int
+	chassis           *types.Chassis           // Store chassis info for later stages
+	status            *bpb.ReportStatusRequest // Store status for later stages
+	clientNonce       string                   // client nonce from bootstrap request
+	serverNonce       string                   // For TPM 2.0 with IDevID nonce challenge
+	hmacSensitive     *tpm2.TPMTSensitive      // For TPM 2.0 without IDevID HMAC challenge
+	challengeSentTime time.Time
 }
 
 type streamSessionV1 struct {
-	stream        bpb.Bootstrap_BootstrapStreamV1Server
-	currentState  int
-	chassis       *types.Chassis           // Store chassis info for later stages
-	status        *bpb.ReportStatusRequest // Store status for later stages
-	clientNonce   string                   // client nonce from bootstrap request
-	serverNonce   []byte                   // For TPM 2.0 with IDevID nonce challenge
-	hmacSensitive *tpm2.TPMTSensitive      // For TPM 2.0 without IDevID HMAC challenge
-	hmacKey       []byte                   // For TPM 1.2 EK challenge
+	stream            bpb.Bootstrap_BootstrapStreamV1Server
+	currentState      int
+	chassis           *types.Chassis           // Store chassis info for later stages
+	status            *bpb.ReportStatusRequest // Store status for later stages
+	clientNonce       string                   // client nonce from bootstrap request
+	serverNonce       []byte                   // For TPM 2.0 with IDevID nonce challenge
+	hmacSensitive     *tpm2.TPMTSensitive      // For TPM 2.0 without IDevID HMAC challenge
+	hmacKey           []byte                   // For TPM 1.2 EK challenge
+	challengeSentTime time.Time
 }
 
 // TPMAsymCAContents is the TPM_ASYM_CA_CONTENTS structure defined in the TPM 1.2 specification.
@@ -344,6 +353,10 @@ func (s *Service) BootstrapStream(stream bpb.Bootstrap_BootstrapStreamServer) er
 				if session.hmacSensitive == nil {
 					return status.Errorf(codes.FailedPrecondition, "received unexpected TPM 2.0 HMAC challenge response")
 				}
+				if elapsed := s.clock.Since(session.challengeSentTime); elapsed > hmacChallengeTimeout {
+					log.Errorf("HMAC challenge timeout exceeded for device %s: took %v, limit %v", session.chassis.ActiveSerial, elapsed, hmacChallengeTimeout)
+					return status.Errorf(codes.DeadlineExceeded, "HMAC challenge timeout exceeded")
+				}
 				hmacResponse := challengeResponse.GetHmacChallengeResponse()
 
 				tpm2BAttest, err := tpm2.Unmarshal[tpm2.TPM2BAttest](hmacResponse.GetIakCertifyInfo())
@@ -537,6 +550,10 @@ func (s *Service) BootstrapStreamV1(stream bpb.Bootstrap_BootstrapStreamV1Server
 				if session.hmacSensitive == nil {
 					return status.Errorf(codes.FailedPrecondition, "received unexpected TPM20HMAC challenge response")
 				}
+				if elapsed := s.clock.Since(session.challengeSentTime); elapsed > hmacChallengeTimeout {
+					log.Errorf("HMAC challenge timeout exceeded for device %s: took %v, limit %v", session.chassis.ActiveSerial, elapsed, hmacChallengeTimeout)
+					return status.Errorf(codes.DeadlineExceeded, "HMAC challenge timeout exceeded")
+				}
 				// Verify HMAC challenge response.
 				mac := challengeResponse.GetTpm20Hmac().GetHmac()
 				tpm2BAttest, err := tpm2.Unmarshal[tpm2.TPM2BAttest](mac.GetIakCertifyInfo())
@@ -710,6 +727,9 @@ func (s *Service) BootstrapStreamV1(stream bpb.Bootstrap_BootstrapStreamV1Server
 			return status.Errorf(codes.Internal, "failed to send BootstrapStreamResponseV1 message: %v", err)
 		}
 		log.Infof("Sent BootstrapStreamResponseV1 message to device %s", session.chassis.ActiveSerial)
+		if (session.currentState == stateChallengeSent || session.currentState == stateReauthChallengeSent) && session.hmacSensitive != nil {
+			session.challengeSentTime = s.clock.Now()
+		}
 	}
 }
 
@@ -1050,6 +1070,9 @@ func (s *Service) establishSessionAndSendChallenge(session *streamSession) error
 		return err
 	}
 	log.Infof("Sent challenge to device %s", session.chassis.ActiveSerial)
+	if session.hmacSensitive != nil {
+		session.challengeSentTime = s.clock.Now()
+	}
 	return nil
 }
 
@@ -1150,5 +1173,6 @@ func New(am ArtifactManager, cm ChassisManager, tpm20 biz.TPM20Utils) (*Service,
 		am:    am,
 		cm:    cm,
 		tpm20: tpm20,
+		clock: clockwork.NewRealClock(),
 	}, nil
 }

server/service/service_test.go

@@ -31,9 +31,11 @@ import (
 	"math/big"
 	"net"
 	"testing"
+	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-tpm/tpm2"
+	"github.com/jonboulle/clockwork"
 	"github.com/openconfig/attestz/service/biz"
 	ownercertificate "github.com/openconfig/bootz/common/owner_certificate"
 	ownershipvoucher "github.com/openconfig/bootz/common/ownership_voucher"
@@ -239,12 +241,13 @@ func TestBootstrapStream(t *testing.T) {
 	idNoIdevid := &bpb.Identity{Type: &bpb.Identity_EkPpkPub{EkPpkPub: true}}
 
 	tests := []struct {
-		name         string
-		req          *bpb.BootstrapStreamRequest
-		id           *bpb.Identity
-		wantErrCode  codes.Code
-		signedNonce  []byte
-		reportStatus bool
+		name                  string
+		req                   *bpb.BootstrapStreamRequest
+		id                    *bpb.Identity
+		wantErrCode           codes.Code
+		wantSecondRecvErrCode codes.Code
+		signedNonce           []byte
+		reportStatus          bool
 	}{
 		{
 			name:        "Missing Identity - Invalid Argument",
@@ -271,6 +274,12 @@ func TestBootstrapStream(t *testing.T) {
 			req:  statusReq,
 			id:   idNoIdevid,
 		},
+		{
+			name:                  "TPM 2.0 no-IDevID Flow Timeout - Failure",
+			req:                   initialReq,
+			id:                    idNoIdevid,
+			wantSecondRecvErrCode: codes.DeadlineExceeded,
+		},
 	}
 
 	for _, test := range tests {
@@ -279,6 +288,11 @@ func TestBootstrapStream(t *testing.T) {
 			if err != nil {
 				t.Fatalf("New() failed: %v", err)
 			}
+			var fakeClock *clockwork.FakeClock
+			if test.name == "TPM 2.0 no-IDevID Flow Timeout - Failure" {
+				fakeClock = clockwork.NewFakeClock()
+				s.clock = fakeClock
+			}
 			srv := grpc.NewServer(grpc.Creds(insecure.NewCredentials()))
 			bpb.RegisterBootstrapServer(srv, s)
 			addr := startTestServer(t, srv)
@@ -371,12 +385,23 @@ func TestBootstrapStream(t *testing.T) {
 			default:
 				t.Fatalf("Unexpected challenge type %T", challengeType)
 			}
+			if fakeClock != nil {
+				fakeClock.Advance(11 * time.Second)
+			}
 			if err := stream.Send(responseReq); err != nil {
 				t.Fatalf("stream.Send(responseReq) failed: %v", err)
 			}
 
 			// === Second Recv: Expect Bootstrap Data or Error ===
 			finalResp, err := stream.Recv()
+			if test.wantSecondRecvErrCode != codes.OK {
+				if err == nil {
+					t.Errorf("stream.Recv() got response %v, want error code %v", finalResp, test.wantSecondRecvErrCode)
+				} else if stat, ok := status.FromError(err); ok && stat.Code() != test.wantSecondRecvErrCode {
+					t.Errorf("stream.Recv() got error code %v, want %v: %v", stat.Code(), test.wantSecondRecvErrCode, err)
+				}
+				return
+			}
 			if err != nil {
 				t.Fatalf("stream.Recv() for final response got unexpected error: %v", err)
 			}
@@ -530,6 +555,12 @@ func TestBootstrapStreamV1(t *testing.T) {
 			id:        idIdevid,
 			wantCodes: []codes.Code{codes.OK, codes.OK},
 		},
+		{
+			name:      "TPM 2.0 EK Flow Timeout - Failure",
+			req:       initialReq,
+			id:        idTPM20EK,
+			wantCodes: []codes.Code{codes.OK, codes.DeadlineExceeded},
+		},
 	}
 
 	for _, test := range tests {
@@ -538,6 +569,11 @@ func TestBootstrapStreamV1(t *testing.T) {
 			if err != nil {
 				t.Fatalf("New() failed: %v", err)
 			}
+			var fakeClock *clockwork.FakeClock
+			if test.name == "TPM 2.0 EK Flow Timeout - Failure" {
+				fakeClock = clockwork.NewFakeClock()
+				s.clock = fakeClock
+			}
 			srv := grpc.NewServer(grpc.Creds(insecure.NewCredentials()))
 			bpb.RegisterBootstrapServer(srv, s)
 			addr := startTestServer(t, srv)
@@ -643,6 +679,9 @@ func TestBootstrapStreamV1(t *testing.T) {
 							},
 						}
 					}
+					if fakeClock != nil {
+						fakeClock.Advance(11 * time.Second)
+					}
 				case 2: // Send Report Status Request.
 					request = proto.Clone(statusReq).(*bpb.BootstrapStreamRequestV1)
 				}