Merge release-20200810.0-22-gb928d074b (automated)

8 files changed, 208 insertions, 90 deletions

diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go
index d0d1efd0d..680eafd16 100644
--- a/pkg/tcpip/header/ipv4.go
+++ b/pkg/tcpip/header/ipv4.go
@@ -315,3 +315,12 @@ func IsV4MulticastAddress(addr tcpip.Address) bool {
 	}
 	return (addr[0] & 0xf0) == 0xe0
 }
+
+// IsV4LoopbackAddress determines if the provided address is an IPv4 loopback
+// address (belongs to 127.0.0.1/8 subnet).
+func IsV4LoopbackAddress(addr tcpip.Address) bool {
+	if len(addr) != IPv4AddressSize {
+		return false
+	}
+	return addr[0] == 0x7f
+}
diff --git a/pkg/tcpip/header/ipv6.go b/pkg/tcpip/header/ipv6.go
index 4f367fe4c..ea3823898 100644
--- a/pkg/tcpip/header/ipv6.go
+++ b/pkg/tcpip/header/ipv6.go
@@ -98,6 +98,9 @@ const (
 	// section 5.
 	IPv6MinimumMTU = 1280
 
+	// IPv6Loopback is the IPv6 Loopback address.
+	IPv6Loopback tcpip.Address = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"
+
 	// IPv6Any is the non-routable IPv6 "any" meta address. It is also
 	// known as the unspecified address.
 	IPv6Any tcpip.Address = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 091bc5281..07c85ce59 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -958,6 +958,26 @@ type SocketDetachFilterOption int
 // and port of a redirected packet.
 type OriginalDestinationOption FullAddress
 
+// TCPTimeWaitReuseOption is used stack.(*Stack).TransportProtocolOption to
+// specify if the stack can reuse the port bound by an endpoint in TIME-WAIT for
+// new connections when it is safe from protocol viewpoint.
+type TCPTimeWaitReuseOption uint8
+
+const (
+	// TCPTimeWaitReuseDisabled indicates reuse of port bound by endponts in TIME-WAIT cannot
+	// be reused for new connections.
+	TCPTimeWaitReuseDisabled TCPTimeWaitReuseOption = iota
+
+	// TCPTimeWaitReuseGlobal indicates reuse of port bound by endponts in TIME-WAIT can
+	// be reused for new connections irrespective of the src/dest addresses.
+	TCPTimeWaitReuseGlobal
+
+	// TCPTimeWaitReuseLoopbackOnly indicates reuse of port bound by endpoint in TIME-WAIT can
+	// only be reused if the connection was a connection over loopback. i.e src/dest adddresses
+	// are loopback addresses.
+	TCPTimeWaitReuseLoopbackOnly
+)
+
 // IPPacketInfo is the message structure for IP_PKTINFO.
 //
 // +stateify savable
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go
index 8dd759ba2..46702906b 100644
--- a/pkg/tcpip/transport/tcp/connect.go
+++ b/pkg/tcpip/transport/tcp/connect.go
@@ -1706,7 +1706,7 @@ func (e *endpoint) doTimeWait() (twReuse func()) {
 			}
 		case notification:
 			n := e.fetchNotifications()
-			if n&notifyClose != 0 || n&notifyAbort != 0 {
+			if n&notifyAbort != 0 {
 				return nil
 			}
 			if n&notifyDrain != 0 {
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index b8b52b03d..d08cfe0ff 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -449,10 +449,11 @@ type endpoint struct {
 	// recentTS is the timestamp that should be sent in the TSEcr field of
 	// the timestamp for future segments sent by the endpoint. This field is
 	// updated if required when a new segment is received by this endpoint.
-	//
-	// recentTS must be read/written atomically.
 	recentTS uint32
 
+	// recentTSTime is the unix time when we updated recentTS last.
+	recentTSTime time.Time `state:".(unixTime)"`
+
 	// tsOffset is a randomized offset added to the value of the
 	// TSVal field in the timestamp option.
 	tsOffset uint32
@@ -795,15 +796,15 @@ func (e *endpoint) EndpointState() EndpointState {
 	return EndpointState(atomic.LoadUint32((*uint32)(&e.state)))
 }
 
-// setRecentTimestamp atomically sets the recentTS field to the
-// provided value.
+// setRecentTimestamp sets the recentTS field to the provided value.
 func (e *endpoint) setRecentTimestamp(recentTS uint32) {
-	atomic.StoreUint32(&e.recentTS, recentTS)
+	e.recentTS = recentTS
+	e.recentTSTime = time.Now()
 }
 
-// recentTimestamp atomically reads and returns the value of the recentTS field.
+// recentTimestamp returns the value of the recentTS field.
 func (e *endpoint) recentTimestamp() uint32 {
-	return atomic.LoadUint32(&e.recentTS)
+	return e.recentTS
 }
 
 // keepalive is a synchronization wrapper used to appease stateify. See the
@@ -902,7 +903,7 @@ func (e *endpoint) Readiness(mask waiter.EventMask) waiter.EventMask {
 	case StateInitial, StateBound, StateConnecting, StateSynSent, StateSynRecv:
 		// Ready for nothing.
 
-	case StateClose, StateError:
+	case StateClose, StateError, StateTimeWait:
 		// Ready for anything.
 		result = mask
 
@@ -2148,12 +2149,66 @@ func (e *endpoint) connect(addr tcpip.FullAddress, handshake bool, run bool) *tc
 		h.Write(portBuf)
 		portOffset := h.Sum32()
 
+		var twReuse tcpip.TCPTimeWaitReuseOption
+		if err := e.stack.TransportProtocolOption(ProtocolNumber, &twReuse); err != nil {
+			panic(fmt.Sprintf("e.stack.TransportProtocolOption(%d, %#v) = %s", ProtocolNumber, &twReuse, err))
+		}
+
+		reuse := twReuse == tcpip.TCPTimeWaitReuseGlobal
+		if twReuse == tcpip.TCPTimeWaitReuseLoopbackOnly {
+			switch netProto {
+			case header.IPv4ProtocolNumber:
+				reuse = header.IsV4LoopbackAddress(e.ID.LocalAddress) && header.IsV4LoopbackAddress(e.ID.RemoteAddress)
+			case header.IPv6ProtocolNumber:
+				reuse = e.ID.LocalAddress == header.IPv6Loopback && e.ID.RemoteAddress == header.IPv6Loopback
+			}
+		}
+
 		if _, err := e.stack.PickEphemeralPortStable(portOffset, func(p uint16) (bool, *tcpip.Error) {
 			if sameAddr && p == e.ID.RemotePort {
 				return false, nil
 			}
 			if _, err := e.stack.ReservePort(netProtos, ProtocolNumber, e.ID.LocalAddress, p, e.portFlags, e.bindToDevice, addr); err != nil {
-				return false, nil
+				if err != tcpip.ErrPortInUse || !reuse {
+					return false, nil
+				}
+				transEPID := e.ID
+				transEPID.LocalPort = p
+				// Check if an endpoint is registered with demuxer in TIME-WAIT and if
+				// we can reuse it. If we can't find a transport endpoint then we just
+				// skip using this port as it's possible that either an endpoint has
+				// bound the port but not registered with demuxer yet (no listen/connect
+				// done yet) or the reservation was freed between the check above and
+				// the FindTransportEndpoint below. But rather than retry the same port
+				// we just skip it and move on.
+				transEP := e.stack.FindTransportEndpoint(netProto, ProtocolNumber, transEPID, &r)
+				if transEP == nil {
+					// ReservePort failed but there is no registered endpoint with
+					// demuxer. Which indicates there is at least some endpoint that has
+					// bound the port.
+					return false, nil
+				}
+
+				tcpEP := transEP.(*endpoint)
+				tcpEP.LockUser()
+				// If the endpoint is not in TIME-WAIT or if it is in TIME-WAIT but
+				// less than 1 second has elapsed since its recentTS was updated then
+				// we cannot reuse the port.
+				if tcpEP.EndpointState() != StateTimeWait || time.Since(tcpEP.recentTSTime) < 1*time.Second {
+					tcpEP.UnlockUser()
+					return false, nil
+				}
+				// Since the endpoint is in TIME-WAIT it should be safe to acquire its
+				// Lock while holding the lock for this endpoint as endpoints in
+				// TIME-WAIT do not acquire locks on other endpoints.
+				tcpEP.workerCleanup = false
+				tcpEP.cleanupLocked()
+				tcpEP.notifyProtocolGoroutine(notifyAbort)
+				tcpEP.UnlockUser()
+				// Now try and Reserve again if it fails then we skip.
+				if _, err := e.stack.ReservePort(netProtos, ProtocolNumber, e.ID.LocalAddress, p, e.portFlags, e.bindToDevice, addr); err != nil {
+					return false, nil
+				}
 			}
 
 			id := e.ID
diff --git a/pkg/tcpip/transport/tcp/endpoint_state.go b/pkg/tcpip/transport/tcp/endpoint_state.go
index abf1ac5c9..723e47ddc 100644
--- a/pkg/tcpip/transport/tcp/endpoint_state.go
+++ b/pkg/tcpip/transport/tcp/endpoint_state.go
@@ -309,6 +309,16 @@ func (e *endpoint) loadLastError(s string) {
 	e.lastError = tcpip.StringToError(s)
 }
 
+// saveRecentTSTime is invoked by stateify.
+func (e *endpoint) saveRecentTSTime() unixTime {
+	return unixTime{e.recentTSTime.Unix(), e.recentTSTime.UnixNano()}
+}
+
+// loadRecentTSTime is invoked by stateify.
+func (e *endpoint) loadRecentTSTime(unix unixTime) {
+	e.recentTSTime = time.Unix(unix.second, unix.nano)
+}
+
 // saveHardError is invoked by stateify.
 func (e *EndpointInfo) saveHardError() string {
 	if e.HardError == nil {
diff --git a/pkg/tcpip/transport/tcp/protocol.go b/pkg/tcpip/transport/tcp/protocol.go
index 2e5093b36..49a673b42 100644
--- a/pkg/tcpip/transport/tcp/protocol.go
+++ b/pkg/tcpip/transport/tcp/protocol.go
@@ -191,8 +191,9 @@ type protocol struct {
 	congestionControl          string
 	availableCongestionControl []string
 	moderateReceiveBuffer      bool
-	tcpLingerTimeout           time.Duration
-	tcpTimeWaitTimeout         time.Duration
+	lingerTimeout              time.Duration
+	timeWaitTimeout            time.Duration
+	timeWaitReuse              tcpip.TCPTimeWaitReuseOption
 	minRTO                     time.Duration
 	maxRTO                     time.Duration
 	maxRetries                 uint32
@@ -358,7 +359,7 @@ func (p *protocol) SetOption(option interface{}) *tcpip.Error {
 			v = 0
 		}
 		p.mu.Lock()
-		p.tcpLingerTimeout = time.Duration(v)
+		p.lingerTimeout = time.Duration(v)
 		p.mu.Unlock()
 		return nil
 
@@ -367,7 +368,16 @@ func (p *protocol) SetOption(option interface{}) *tcpip.Error {
 			v = 0
 		}
 		p.mu.Lock()
-		p.tcpTimeWaitTimeout = time.Duration(v)
+		p.timeWaitTimeout = time.Duration(v)
+		p.mu.Unlock()
+		return nil
+
+	case tcpip.TCPTimeWaitReuseOption:
+		if v < tcpip.TCPTimeWaitReuseDisabled || v > tcpip.TCPTimeWaitReuseLoopbackOnly {
+			return tcpip.ErrInvalidOptionValue
+		}
+		p.mu.Lock()
+		p.timeWaitReuse = v
 		p.mu.Unlock()
 		return nil
 
@@ -468,13 +478,19 @@ func (p *protocol) Option(option interface{}) *tcpip.Error {
 
 	case *tcpip.TCPLingerTimeoutOption:
 		p.mu.RLock()
-		*v = tcpip.TCPLingerTimeoutOption(p.tcpLingerTimeout)
+		*v = tcpip.TCPLingerTimeoutOption(p.lingerTimeout)
 		p.mu.RUnlock()
 		return nil
 
 	case *tcpip.TCPTimeWaitTimeoutOption:
 		p.mu.RLock()
-		*v = tcpip.TCPTimeWaitTimeoutOption(p.tcpTimeWaitTimeout)
+		*v = tcpip.TCPTimeWaitTimeoutOption(p.timeWaitTimeout)
+		p.mu.RUnlock()
+		return nil
+
+	case *tcpip.TCPTimeWaitReuseOption:
+		p.mu.RLock()
+		*v = tcpip.TCPTimeWaitReuseOption(p.timeWaitReuse)
 		p.mu.RUnlock()
 		return nil
 
@@ -564,8 +580,9 @@ func NewProtocol() stack.TransportProtocol {
 		},
 		congestionControl:          ccReno,
 		availableCongestionControl: []string{ccReno, ccCubic},
-		tcpLingerTimeout:           DefaultTCPLingerTimeout,
-		tcpTimeWaitTimeout:         DefaultTCPTimeWaitTimeout,
+		lingerTimeout:              DefaultTCPLingerTimeout,
+		timeWaitTimeout:            DefaultTCPTimeWaitTimeout,
+		timeWaitReuse:              tcpip.TCPTimeWaitReuseLoopbackOnly,
 		synRcvdCount:               synRcvdCounter{threshold: SynRcvdCountThreshold},
 		synRetries:                 DefaultSynRetries,
 		minRTO:                     MinRTO,
diff --git a/pkg/tcpip/transport/tcp/tcp_state_autogen.go b/pkg/tcpip/transport/tcp/tcp_state_autogen.go
index 132131815..bed45e9a1 100644
--- a/pkg/tcpip/transport/tcp/tcp_state_autogen.go
+++ b/pkg/tcpip/transport/tcp/tcp_state_autogen.go
@@ -185,6 +185,7 @@ func (x *endpoint) StateFields() []string {
 		"workerCleanup",
 		"sendTSOk",
 		"recentTS",
+		"recentTSTime",
 		"tsOffset",
 		"shutdownFlags",
 		"sackPermitted",
@@ -230,8 +231,10 @@ func (x *endpoint) StateSave(m state.Sink) {
 	m.SaveValue(3, lastError)
 	var state EndpointState = x.saveState()
 	m.SaveValue(10, state)
+	var recentTSTime unixTime = x.saveRecentTSTime()
+	m.SaveValue(25, recentTSTime)
 	var acceptedChan []*endpoint = x.saveAcceptedChan()
-	m.SaveValue(50, acceptedChan)
+	m.SaveValue(51, acceptedChan)
 	m.Save(0, &x.EndpointInfo)
 	m.Save(1, &x.waiterQueue)
 	m.Save(2, &x.uniqueID)
@@ -255,41 +258,41 @@ func (x *endpoint) StateSave(m state.Sink) {
 	m.Save(22, &x.workerCleanup)
 	m.Save(23, &x.sendTSOk)
 	m.Save(24, &x.recentTS)
-	m.Save(25, &x.tsOffset)
-	m.Save(26, &x.shutdownFlags)
-	m.Save(27, &x.sackPermitted)
-	m.Save(28, &x.sack)
-	m.Save(29, &x.bindToDevice)
-	m.Save(30, &x.delay)
-	m.Save(31, &x.cork)
-	m.Save(32, &x.scoreboard)
-	m.Save(33, &x.slowAck)
-	m.Save(34, &x.segmentQueue)
-	m.Save(35, &x.synRcvdCount)
-	m.Save(36, &x.userMSS)
-	m.Save(37, &x.maxSynRetries)
-	m.Save(38, &x.windowClamp)
-	m.Save(39, &x.sndBufSize)
-	m.Save(40, &x.sndBufUsed)
-	m.Save(41, &x.sndClosed)
-	m.Save(42, &x.sndBufInQueue)
-	m.Save(43, &x.sndQueue)
-	m.Save(44, &x.cc)
-	m.Save(45, &x.packetTooBigCount)
-	m.Save(46, &x.sndMTU)
-	m.Save(47, &x.keepalive)
-	m.Save(48, &x.userTimeout)
-	m.Save(49, &x.deferAccept)
-	m.Save(51, &x.rcv)
-	m.Save(52, &x.snd)
-	m.Save(53, &x.connectingAddress)
-	m.Save(54, &x.amss)
-	m.Save(55, &x.sendTOS)
-	m.Save(56, &x.gso)
-	m.Save(57, &x.tcpLingerTimeout)
-	m.Save(58, &x.closed)
-	m.Save(59, &x.txHash)
-	m.Save(60, &x.owner)
+	m.Save(26, &x.tsOffset)
+	m.Save(27, &x.shutdownFlags)
+	m.Save(28, &x.sackPermitted)
+	m.Save(29, &x.sack)
+	m.Save(30, &x.bindToDevice)
+	m.Save(31, &x.delay)
+	m.Save(32, &x.cork)
+	m.Save(33, &x.scoreboard)
+	m.Save(34, &x.slowAck)
+	m.Save(35, &x.segmentQueue)
+	m.Save(36, &x.synRcvdCount)
+	m.Save(37, &x.userMSS)
+	m.Save(38, &x.maxSynRetries)
+	m.Save(39, &x.windowClamp)
+	m.Save(40, &x.sndBufSize)
+	m.Save(41, &x.sndBufUsed)
+	m.Save(42, &x.sndClosed)
+	m.Save(43, &x.sndBufInQueue)
+	m.Save(44, &x.sndQueue)
+	m.Save(45, &x.cc)
+	m.Save(46, &x.packetTooBigCount)
+	m.Save(47, &x.sndMTU)
+	m.Save(48, &x.keepalive)
+	m.Save(49, &x.userTimeout)
+	m.Save(50, &x.deferAccept)
+	m.Save(52, &x.rcv)
+	m.Save(53, &x.snd)
+	m.Save(54, &x.connectingAddress)
+	m.Save(55, &x.amss)
+	m.Save(56, &x.sendTOS)
+	m.Save(57, &x.gso)
+	m.Save(58, &x.tcpLingerTimeout)
+	m.Save(59, &x.closed)
+	m.Save(60, &x.txHash)
+	m.Save(61, &x.owner)
 }
 
 func (x *endpoint) StateLoad(m state.Source) {
@@ -316,44 +319,45 @@ func (x *endpoint) StateLoad(m state.Source) {
 	m.Load(22, &x.workerCleanup)
 	m.Load(23, &x.sendTSOk)
 	m.Load(24, &x.recentTS)
-	m.Load(25, &x.tsOffset)
-	m.Load(26, &x.shutdownFlags)
-	m.Load(27, &x.sackPermitted)
-	m.Load(28, &x.sack)
-	m.Load(29, &x.bindToDevice)
-	m.Load(30, &x.delay)
-	m.Load(31, &x.cork)
-	m.Load(32, &x.scoreboard)
-	m.Load(33, &x.slowAck)
-	m.LoadWait(34, &x.segmentQueue)
-	m.Load(35, &x.synRcvdCount)
-	m.Load(36, &x.userMSS)
-	m.Load(37, &x.maxSynRetries)
-	m.Load(38, &x.windowClamp)
-	m.Load(39, &x.sndBufSize)
-	m.Load(40, &x.sndBufUsed)
-	m.Load(41, &x.sndClosed)
-	m.Load(42, &x.sndBufInQueue)
-	m.LoadWait(43, &x.sndQueue)
-	m.Load(44, &x.cc)
-	m.Load(45, &x.packetTooBigCount)
-	m.Load(46, &x.sndMTU)
-	m.Load(47, &x.keepalive)
-	m.Load(48, &x.userTimeout)
-	m.Load(49, &x.deferAccept)
-	m.LoadWait(51, &x.rcv)
-	m.LoadWait(52, &x.snd)
-	m.Load(53, &x.connectingAddress)
-	m.Load(54, &x.amss)
-	m.Load(55, &x.sendTOS)
-	m.Load(56, &x.gso)
-	m.Load(57, &x.tcpLingerTimeout)
-	m.Load(58, &x.closed)
-	m.Load(59, &x.txHash)
-	m.Load(60, &x.owner)
+	m.Load(26, &x.tsOffset)
+	m.Load(27, &x.shutdownFlags)
+	m.Load(28, &x.sackPermitted)
+	m.Load(29, &x.sack)
+	m.Load(30, &x.bindToDevice)
+	m.Load(31, &x.delay)
+	m.Load(32, &x.cork)
+	m.Load(33, &x.scoreboard)
+	m.Load(34, &x.slowAck)
+	m.LoadWait(35, &x.segmentQueue)
+	m.Load(36, &x.synRcvdCount)
+	m.Load(37, &x.userMSS)
+	m.Load(38, &x.maxSynRetries)
+	m.Load(39, &x.windowClamp)
+	m.Load(40, &x.sndBufSize)
+	m.Load(41, &x.sndBufUsed)
+	m.Load(42, &x.sndClosed)
+	m.Load(43, &x.sndBufInQueue)
+	m.LoadWait(44, &x.sndQueue)
+	m.Load(45, &x.cc)
+	m.Load(46, &x.packetTooBigCount)
+	m.Load(47, &x.sndMTU)
+	m.Load(48, &x.keepalive)
+	m.Load(49, &x.userTimeout)
+	m.Load(50, &x.deferAccept)
+	m.LoadWait(52, &x.rcv)
+	m.LoadWait(53, &x.snd)
+	m.Load(54, &x.connectingAddress)
+	m.Load(55, &x.amss)
+	m.Load(56, &x.sendTOS)
+	m.Load(57, &x.gso)
+	m.Load(58, &x.tcpLingerTimeout)
+	m.Load(59, &x.closed)
+	m.Load(60, &x.txHash)
+	m.Load(61, &x.owner)
 	m.LoadValue(3, new(string), func(y interface{}) { x.loadLastError(y.(string)) })
 	m.LoadValue(10, new(EndpointState), func(y interface{}) { x.loadState(y.(EndpointState)) })
-	m.LoadValue(50, new([]*endpoint), func(y interface{}) { x.loadAcceptedChan(y.([]*endpoint)) })
+	m.LoadValue(25, new(unixTime), func(y interface{}) { x.loadRecentTSTime(y.(unixTime)) })
+	m.LoadValue(51, new([]*endpoint), func(y interface{}) { x.loadAcceptedChan(y.([]*endpoint)) })
 	m.AfterLoad(x.afterLoad)
 }