Enable RACK by default in netstack.

PiperOrigin-RevId: 385944428

pkg/tcpip/transport/tcp/endpoint.go

@@ -478,7 +478,7 @@ type endpoint struct {
 	// shutdownFlags represent the current shutdown state of the endpoint.
 	shutdownFlags tcpip.ShutdownFlags
 
-	// tcpRecovery is the loss deteoction algorithm used by TCP.
+	// tcpRecovery is the loss recovery algorithm used by TCP.
 	tcpRecovery tcpip.TCPRecovery
 
 	// sack holds TCP SACK related information for this endpoint.
@@ -869,8 +869,6 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQue
 		e.maxSynRetries = uint8(synRetries)
 	}
 
-	s.TransportProtocolOption(ProtocolNumber, &e.tcpRecovery)
-
 	if p := s.GetTCPProbe(); p != nil {
 		e.probe = p
 	}
@@ -2922,6 +2920,7 @@ func (e *endpoint) maybeEnableSACKPermitted(synOpts *header.TCPSynOptions) {
 	}
 	if bool(v) && synOpts.SACKPermitted {
 		e.SACKPermitted = true
+		e.stack.TransportProtocolOption(ProtocolNumber, &e.tcpRecovery)
 	}
 }
 

pkg/tcpip/transport/tcp/protocol.go

@@ -478,8 +478,7 @@ func NewProtocol(s *stack.Stack) stack.TransportProtocol {
 		minRTO:                     MinRTO,
 		maxRTO:                     MaxRTO,
 		maxRetries:                 MaxRetries,
-		// TODO(gvisor.dev/issue/5243): Set recovery to tcpip.TCPRACKLossDetection.
-		recovery: 0,
+		recovery:                   tcpip.TCPRACKLossDetection,
 	}
 	p.dispatcher.init(s.Rand(), runtime.GOMAXPROCS(0))
 	return &p

pkg/tcpip/transport/tcp/tcp_rack_test.go

@@ -36,9 +36,9 @@ const (
 	latency          = 5 * time.Millisecond
 )
 
-func setStackRACKPermitted(t *testing.T, c *context.Context) {
+func setStackTCPRecovery(t *testing.T, c *context.Context, recovery int) {
 	t.Helper()
-	opt := tcpip.TCPRACKLossDetection
+	opt := tcpip.TCPRecovery(recovery)
 	if err := c.Stack().SetTransportProtocolOption(header.TCPProtocolNumber, &opt); err != nil {
 		t.Fatalf("c.s.SetTransportProtocolOption(%d, &%v(%v)): %s", header.TCPProtocolNumber, opt, opt, err)
 	}
@@ -70,7 +70,6 @@ func TestRACKUpdate(t *testing.T) {
 		close(probeDone)
 	})
 	setStackSACKPermitted(t, c, true)
-	setStackRACKPermitted(t, c)
 	createConnectedWithSACKAndTS(c)
 
 	data := make([]byte, maxPayload)
@@ -129,7 +128,6 @@ func TestRACKDetectReorder(t *testing.T) {
 		close(probeDone)
 	})
 	setStackSACKPermitted(t, c, true)
-	setStackRACKPermitted(t, c)
 	createConnectedWithSACKAndTS(c)
 	data := make([]byte, ackNumToVerify*maxPayload)
 	for i := range data {
@@ -162,8 +160,8 @@ func TestRACKDetectReorder(t *testing.T) {
 
 func sendAndReceiveWithSACK(t *testing.T, c *context.Context, numPackets int, enableRACK bool) []byte {
 	setStackSACKPermitted(t, c, true)
-	if enableRACK {
-		setStackRACKPermitted(t, c)
+	if !enableRACK {
+		setStackTCPRecovery(t, c, 0)
 	}
 	createConnectedWithSACKAndTS(c)
 
@@ -998,7 +996,6 @@ func TestRACKWithWindowFull(t *testing.T) {
 	defer c.Cleanup()
 
 	setStackSACKPermitted(t, c, true)
-	setStackRACKPermitted(t, c)
 	createConnectedWithSACKAndTS(c)
 
 	seq := seqnum.Value(context.TestInitialSequenceNumber).Add(1)

pkg/tcpip/transport/tcp/tcp_sack_test.go

@@ -61,6 +61,7 @@ func TestSackPermittedConnect(t *testing.T) {
 			defer c.Cleanup()
 
 			setStackSACKPermitted(t, c, sackEnabled)
+			setStackTCPRecovery(t, c, 0)
 			rep := createConnectedWithSACKPermittedOption(c)
 			data := []byte{1, 2, 3}
 
@@ -105,6 +106,7 @@ func TestSackDisabledConnect(t *testing.T) {
 			defer c.Cleanup()
 
 			setStackSACKPermitted(t, c, sackEnabled)
+			setStackTCPRecovery(t, c, 0)
 
 			rep := c.CreateConnectedWithOptions(header.TCPSynOptions{})
 
@@ -166,6 +168,7 @@ func TestSackPermittedAccept(t *testing.T) {
 						}
 					}
 					setStackSACKPermitted(t, c, sackEnabled)
+					setStackTCPRecovery(t, c, 0)
 
 					rep := c.AcceptWithOptions(tc.wndScale, header.TCPSynOptions{MSS: defaultIPv4MSS, SACKPermitted: tc.sackPermitted})
 					//  Now verify no SACK blocks are
@@ -239,6 +242,7 @@ func TestSackDisabledAccept(t *testing.T) {
 					}
 
 					setStackSACKPermitted(t, c, sackEnabled)
+					setStackTCPRecovery(t, c, 0)
 
 					rep := c.AcceptWithOptions(tc.wndScale, header.TCPSynOptions{MSS: defaultIPv4MSS})
 
@@ -386,6 +390,7 @@ func TestSACKRecovery(t *testing.T) {
 		log.Printf("state: %+v\n", s)
 	})
 	setStackSACKPermitted(t, c, true)
+	setStackTCPRecovery(t, c, 0)
 	createConnectedWithSACKAndTS(c)
 
 	const iterations = 3

test/syscalls/linux/proc_net.cc

@@ -498,13 +498,7 @@ TEST(ProcSysNetIpv4Recovery, CanReadAndWrite) {
   // Check initial value is set to 1.
   EXPECT_THAT(PreadFd(fd.get(), &buf, sizeof(buf), 0),
               SyscallSucceedsWithValue(sizeof(to_write) + 1));
-  if (IsRunningOnGvisor()) {
-    // TODO(gvisor.dev/issue/5243): TCPRACKLossDetection = 1 should be turned on
-    // by default.
-    EXPECT_EQ(strcmp(buf, "0\n"), 0);
-  } else {
-    EXPECT_EQ(strcmp(buf, "1\n"), 0);
-  }
+  EXPECT_EQ(strcmp(buf, "1\n"), 0);
 
   // Set tcp_recovery to one of the allowed constants.
   EXPECT_THAT(PwriteFd(fd.get(), &to_write, sizeof(to_write), 0),