From 13a98df49ea1b36cd21c528293b626a6a3639f0b Mon Sep 17 00:00:00 2001
From: Rahat Mahmood <rahat@google.com>
Date: Thu, 8 Aug 2019 12:32:00 -0700
Subject: netstack: Don't start endpoint goroutines too soon on restore.

Endpoint protocol goroutines were previously started as part of
loading the endpoint. This is potentially too soon, as resources used
by these goroutine may not have been loaded. Protocol goroutines may
perform meaningful work as soon as they're started (ex: incoming
connect) which can cause them to indirectly access resources that
haven't been loaded yet.

This CL defers resuming all protocol goroutines until the end of
restore.

PiperOrigin-RevId: 262409429
---
 pkg/tcpip/transport/tcp/endpoint.go | 101 ++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)

(limited to 'pkg/tcpip/transport/tcp/endpoint.go')

diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 0e16877e7..e67169111 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -720,6 +720,107 @@ func (e *endpoint) IPTables() (iptables.IPTables, error) {
 	return e.stack.IPTables(), nil
 }
 
+// Resume implements tcpip.ResumableEndpoint.Resume.
+func (e *endpoint) Resume(s *stack.Stack) {
+	e.stack = s
+	e.segmentQueue.setLimit(MaxUnprocessedSegments)
+	e.workMu.Init()
+
+	state := e.state
+	switch state {
+	case StateInitial, StateBound, StateListen, StateConnecting, StateEstablished:
+		var ss SendBufferSizeOption
+		if err := e.stack.TransportProtocolOption(ProtocolNumber, &ss); err == nil {
+			if e.sndBufSize < ss.Min || e.sndBufSize > ss.Max {
+				panic(fmt.Sprintf("endpoint.sndBufSize %d is outside the min and max allowed [%d, %d]", e.sndBufSize, ss.Min, ss.Max))
+			}
+			if e.rcvBufSize < ss.Min || e.rcvBufSize > ss.Max {
+				panic(fmt.Sprintf("endpoint.rcvBufSize %d is outside the min and max allowed [%d, %d]", e.rcvBufSize, ss.Min, ss.Max))
+			}
+		}
+	}
+
+	bind := func() {
+		e.state = StateInitial
+		if len(e.bindAddress) == 0 {
+			e.bindAddress = e.id.LocalAddress
+		}
+		if err := e.Bind(tcpip.FullAddress{Addr: e.bindAddress, Port: e.id.LocalPort}); err != nil {
+			panic("endpoint binding failed: " + err.String())
+		}
+	}
+
+	switch state {
+	case StateEstablished, StateFinWait1, StateFinWait2, StateTimeWait, StateCloseWait, StateLastAck, StateClosing:
+		bind()
+		if len(e.connectingAddress) == 0 {
+			e.connectingAddress = e.id.RemoteAddress
+			// This endpoint is accepted by netstack but not yet by
+			// the app. If the endpoint is IPv6 but the remote
+			// address is IPv4, we need to connect as IPv6 so that
+			// dual-stack mode can be properly activated.
+			if e.netProto == header.IPv6ProtocolNumber && len(e.id.RemoteAddress) != header.IPv6AddressSize {
+				e.connectingAddress = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff" + e.id.RemoteAddress
+			}
+		}
+		// Reset the scoreboard to reinitialize the sack information as
+		// we do not restore SACK information.
+		e.scoreboard.Reset()
+		if err := e.connect(tcpip.FullAddress{NIC: e.boundNICID, Addr: e.connectingAddress, Port: e.id.RemotePort}, false, e.workerRunning); err != tcpip.ErrConnectStarted {
+			panic("endpoint connecting failed: " + err.String())
+		}
+		connectedLoading.Done()
+	case StateListen:
+		tcpip.AsyncLoading.Add(1)
+		go func() {
+			connectedLoading.Wait()
+			bind()
+			backlog := cap(e.acceptedChan)
+			if err := e.Listen(backlog); err != nil {
+				panic("endpoint listening failed: " + err.String())
+			}
+			listenLoading.Done()
+			tcpip.AsyncLoading.Done()
+		}()
+	case StateConnecting, StateSynSent, StateSynRecv:
+		tcpip.AsyncLoading.Add(1)
+		go func() {
+			connectedLoading.Wait()
+			listenLoading.Wait()
+			bind()
+			if err := e.Connect(tcpip.FullAddress{NIC: e.boundNICID, Addr: e.connectingAddress, Port: e.id.RemotePort}); err != tcpip.ErrConnectStarted {
+				panic("endpoint connecting failed: " + err.String())
+			}
+			connectingLoading.Done()
+			tcpip.AsyncLoading.Done()
+		}()
+	case StateBound:
+		tcpip.AsyncLoading.Add(1)
+		go func() {
+			connectedLoading.Wait()
+			listenLoading.Wait()
+			connectingLoading.Wait()
+			bind()
+			tcpip.AsyncLoading.Done()
+		}()
+	case StateClose:
+		if e.isPortReserved {
+			tcpip.AsyncLoading.Add(1)
+			go func() {
+				connectedLoading.Wait()
+				listenLoading.Wait()
+				connectingLoading.Wait()
+				bind()
+				e.state = StateClose
+				tcpip.AsyncLoading.Done()
+			}()
+		}
+		fallthrough
+	case StateError:
+		tcpip.DeleteDanglingEndpoint(e)
+	}
+}
+
 // Read reads data from the endpoint.
 func (e *endpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
 	e.mu.RLock()
-- 
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