Merge release-20201208.0-127-gb1de1da31 (automated)

14 files changed, 470 insertions, 482 deletions

diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index fe11fca9c..dcf898c0a 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -28,9 +28,9 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"math"
 	"reflect"
-	"sync/atomic"
 	"syscall"
 	"time"
 
@@ -43,7 +43,6 @@ import (
 	"gvisor.dev/gvisor/pkg/marshal"
 	"gvisor.dev/gvisor/pkg/marshal/primitive"
 	"gvisor.dev/gvisor/pkg/metric"
-	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
@@ -308,16 +307,8 @@ type socketOpsCommon struct {
 	skType   linux.SockType
 	protocol int
 
-	// readViewHasData is 1 iff readView has data to be read, 0 otherwise.
-	// Must be accessed using atomic operations. It must only be written
-	// with readMu held but can be read without holding readMu. The latter
-	// is required to avoid deadlocks in epoll Readiness checks.
-	readViewHasData uint32
-
 	// readMu protects access to the below fields.
 	readMu sync.Mutex `state:"nosave"`
-	// readView contains the remaining payload from the last packet.
-	readView buffer.View
 	// readCM holds control message information for the last packet read
 	// from Endpoint.
 	readCM         socket.IPControlMessages
@@ -336,8 +327,8 @@ type socketOpsCommon struct {
 	// valid when timestampValid is true. It is protected by readMu.
 	timestampNS int64
 
-	// sockOptInq corresponds to TCP_INQ. It is implemented at this level
-	// because it takes into account data from readView.
+	// TODO(b/153685824): Move this to SocketOptions.
+	// sockOptInq corresponds to TCP_INQ.
 	sockOptInq bool
 }
 
@@ -377,41 +368,23 @@ func (s *socketOpsCommon) isPacketBased() bool {
 	return s.skType == linux.SOCK_DGRAM || s.skType == linux.SOCK_SEQPACKET || s.skType == linux.SOCK_RDM || s.skType == linux.SOCK_RAW
 }
 
-// fetchReadView updates the readView field of the socket if it's currently
-// empty. It assumes that the socket is locked.
-//
 // Precondition: s.readMu must be held.
-func (s *socketOpsCommon) fetchReadView() *syserr.Error {
-	if len(s.readView) > 0 {
-		return nil
-	}
-	s.readView = nil
-	s.sender = tcpip.FullAddress{}
-	s.linkPacketInfo = tcpip.LinkPacketInfo{}
+func (s *socketOpsCommon) readLocked(dst io.Writer, count int, peek bool) (numRead, numTotal int, serr *syserr.Error) {
+	res, err := s.Endpoint.Read(dst, count, tcpip.ReadOptions{
+		Peek:               peek,
+		NeedRemoteAddr:     true,
+		NeedLinkPacketInfo: true,
+	})
 
-	var v buffer.View
-	var cms tcpip.ControlMessages
-	var err *tcpip.Error
+	// Assign these anyways.
+	s.readCM = socket.NewIPControlMessages(s.family, res.ControlMessages)
+	s.sender = res.RemoteAddr
+	s.linkPacketInfo = res.LinkPacketInfo
 
-	switch e := s.Endpoint.(type) {
-	// The ordering of these interfaces matters. The most specific
-	// interfaces must be specified before the more generic Endpoint
-	// interface.
-	case tcpip.PacketEndpoint:
-		v, cms, err = e.ReadPacket(&s.sender, &s.linkPacketInfo)
-	case tcpip.Endpoint:
-		v, cms, err = e.Read(&s.sender)
-	}
 	if err != nil {
-		atomic.StoreUint32(&s.readViewHasData, 0)
-		return syserr.TranslateNetstackError(err)
+		return 0, 0, syserr.TranslateNetstackError(err)
 	}
-
-	s.readView = v
-	s.readCM = socket.NewIPControlMessages(s.family, cms)
-	atomic.StoreUint32(&s.readViewHasData, 1)
-
-	return nil
+	return res.Count, res.Total, nil
 }
 
 // Release implements fs.FileOperations.Release.
@@ -460,38 +433,14 @@ func (s *SocketOperations) Read(ctx context.Context, _ *fs.File, dst usermem.IOS
 // WriteTo implements fs.FileOperations.WriteTo.
 func (s *SocketOperations) WriteTo(ctx context.Context, _ *fs.File, dst io.Writer, count int64, dup bool) (int64, error) {
 	s.readMu.Lock()
+	defer s.readMu.Unlock()
 
-	// Copy as much data as possible.
-	done := int64(0)
-	for count > 0 {
-		// This may return a blocking error.
-		if err := s.fetchReadView(); err != nil {
-			s.readMu.Unlock()
-			return done, err.ToError()
-		}
-
-		// Write to the underlying file.
-		n, err := dst.Write(s.readView)
-		done += int64(n)
-		count -= int64(n)
-		if dup {
-			// That's all we support for dup. This is generally
-			// supported by any Linux system calls, but the
-			// expectation is that now a caller will call read to
-			// actually remove these bytes from the socket.
-			break
-		}
-
-		// Drop that part of the view.
-		s.readView.TrimFront(n)
-		if err != nil {
-			s.readMu.Unlock()
-			return done, err
-		}
+	// This may return a blocking error.
+	n, _, err := s.readLocked(dst, int(count), dup /* peek */)
+	if err != nil {
+		return 0, err.ToError()
 	}
-
-	s.readMu.Unlock()
-	return done, nil
+	return int64(n), nil
 }
 
 // ioSequencePayload implements tcpip.Payload.
@@ -627,17 +576,7 @@ func (s *SocketOperations) ReadFrom(ctx context.Context, _ *fs.File, r io.Reader
 
 // Readiness returns a mask of ready events for socket s.
 func (s *socketOpsCommon) Readiness(mask waiter.EventMask) waiter.EventMask {
-	r := s.Endpoint.Readiness(mask)
-
-	// Check our cached value iff the caller asked for readability and the
-	// endpoint itself is currently not readable.
-	if (mask & ^r & waiter.EventIn) != 0 {
-		if atomic.LoadUint32(&s.readViewHasData) == 1 {
-			r |= waiter.EventIn
-		}
-	}
-
-	return r
+	return s.Endpoint.Readiness(mask)
 }
 
 func (s *socketOpsCommon) checkFamily(family uint16, exact bool) *syserr.Error {
@@ -2618,66 +2557,20 @@ func (s *socketOpsCommon) GetPeerName(t *kernel.Task) (linux.SockAddr, uint32, *
 	return a, l, nil
 }
 
-// coalescingRead is the fast path for non-blocking, non-peek, stream-based
-// case. It coalesces as many packets as possible before returning to the
-// caller.
+// streamRead is the fast path for non-blocking, non-peek, stream-based socket.
 //
 // Precondition: s.readMu must be locked.
-func (s *socketOpsCommon) coalescingRead(ctx context.Context, dst usermem.IOSequence, discard bool) (int, *syserr.Error) {
-	var err *syserr.Error
-	var copied int
-
-	// Copy as many views as possible into the user-provided buffer.
-	for {
-		// Always do at least one fetchReadView, even if the number of bytes to
-		// read is 0.
-		err = s.fetchReadView()
-		if err != nil || len(s.readView) == 0 {
-			break
-		}
-		if dst.NumBytes() == 0 {
-			break
-		}
-
-		var n int
-		var e error
-		if discard {
-			n = len(s.readView)
-			if int64(n) > dst.NumBytes() {
-				n = int(dst.NumBytes())
-			}
-		} else {
-			n, e = dst.CopyOut(ctx, s.readView)
-			// Set the control message, even if 0 bytes were read.
-			if e == nil {
-				s.updateTimestamp()
-			}
-		}
-		copied += n
-		s.readView.TrimFront(n)
-
-		dst = dst.DropFirst(n)
-		if e != nil {
-			err = syserr.FromError(e)
-			break
-		}
-		// If we are done reading requested data then stop.
-		if dst.NumBytes() == 0 {
-			break
-		}
-	}
-
-	if len(s.readView) == 0 {
-		atomic.StoreUint32(&s.readViewHasData, 0)
+func (s *socketOpsCommon) streamRead(ctx context.Context, dst io.Writer, count int) (int, *syserr.Error) {
+	// Always do at least one read, even if the number of bytes to read is 0.
+	var n int
+	n, _, err := s.readLocked(dst, count, false /* peek */)
+	if err != nil {
+		return 0, err
 	}
-
-	// If we managed to copy something, we must deliver it.
-	if copied > 0 {
-		s.Endpoint.ModerateRecvBuf(copied)
-		return copied, nil
+	if n > 0 {
+		s.Endpoint.ModerateRecvBuf(n)
 	}
-
-	return 0, err
+	return n, nil
 }
 
 func (s *socketOpsCommon) fillCmsgInq(cmsg *socket.ControlMessages) {
@@ -2689,7 +2582,7 @@ func (s *socketOpsCommon) fillCmsgInq(cmsg *socket.ControlMessages) {
 		return
 	}
 	cmsg.IP.HasInq = true
-	cmsg.IP.Inq = int32(len(s.readView) + rcvBufUsed)
+	cmsg.IP.Inq = int32(rcvBufUsed)
 }
 
 func toLinuxPacketType(pktType tcpip.PacketType) uint8 {
@@ -2726,7 +2619,21 @@ func (s *socketOpsCommon) nonBlockingRead(ctx context.Context, dst usermem.IOSeq
 		// bytes of data to be discarded, rather than passed back in a
 		// caller-supplied  buffer.
 		s.readMu.Lock()
-		n, err := s.coalescingRead(ctx, dst, trunc)
+
+		var w io.Writer
+		if trunc {
+			w = ioutil.Discard
+		} else {
+			w = dst.Writer(ctx)
+		}
+
+		n, err := s.streamRead(ctx, w, int(dst.NumBytes()))
+
+		if err == nil && !trunc {
+			// Set the control message, even if 0 bytes were read.
+			s.updateTimestamp()
+		}
+
 		cmsg := s.controlMessages()
 		s.fillCmsgInq(&cmsg)
 		s.readMu.Unlock()
@@ -2736,18 +2643,32 @@ func (s *socketOpsCommon) nonBlockingRead(ctx context.Context, dst usermem.IOSeq
 	s.readMu.Lock()
 	defer s.readMu.Unlock()
 
-	if err := s.fetchReadView(); err != nil {
+	// MSG_TRUNC with MSG_PEEK on a TCP socket returns the
+	// amount that could be read, and does not write to buffer.
+	isTCPPeekTrunc := !isPacket && peek && trunc
+
+	var w io.Writer
+	if isTCPPeekTrunc {
+		w = ioutil.Discard
+	} else {
+		w = dst.Writer(ctx)
+	}
+
+	var numRead, numTotal int
+	var err *syserr.Error
+	numRead, numTotal, err = s.readLocked(w, int(dst.NumBytes()), peek)
+	if err != nil {
 		return 0, 0, nil, 0, socket.ControlMessages{}, err
 	}
 
-	if !isPacket && peek && trunc {
-		// MSG_TRUNC with MSG_PEEK on a TCP socket returns the
-		// amount that could be read.
+	if isTCPPeekTrunc {
+		// TCP endpoint does not return the total bytes in buffer as numTotal.
+		// We need to query it from socket option.
 		rql, err := s.Endpoint.GetSockOptInt(tcpip.ReceiveQueueSizeOption)
 		if err != nil {
 			return 0, 0, nil, 0, socket.ControlMessages{}, syserr.TranslateNetstackError(err)
 		}
-		available := len(s.readView) + int(rql)
+		available := int(rql)
 		bufLen := int(dst.NumBytes())
 		if available < bufLen {
 			return available, 0, nil, 0, socket.ControlMessages{}, nil
@@ -2755,11 +2676,9 @@ func (s *socketOpsCommon) nonBlockingRead(ctx context.Context, dst usermem.IOSeq
 		return bufLen, 0, nil, 0, socket.ControlMessages{}, nil
 	}
 
-	n, err := dst.CopyOut(ctx, s.readView)
 	// Set the control message, even if 0 bytes were read.
-	if err == nil {
-		s.updateTimestamp()
-	}
+	s.updateTimestamp()
+
 	var addr linux.SockAddr
 	var addrLen uint32
 	if isPacket && senderRequested {
@@ -2772,58 +2691,33 @@ func (s *socketOpsCommon) nonBlockingRead(ctx context.Context, dst usermem.IOSeq
 	}
 
 	if peek {
-		if l := len(s.readView); trunc && l > n {
+		if trunc && numTotal > numRead {
 			// isPacket must be true.
-			return l, linux.MSG_TRUNC, addr, addrLen, s.controlMessages(), syserr.FromError(err)
+			return numTotal, linux.MSG_TRUNC, addr, addrLen, s.controlMessages(), nil
 		}
-
-		if isPacket || err != nil {
-			return n, 0, addr, addrLen, s.controlMessages(), syserr.FromError(err)
-		}
-
-		// We need to peek beyond the first message.
-		dst = dst.DropFirst(n)
-		num, err := dst.CopyOutFrom(ctx, safemem.FromVecReaderFunc{func(dsts [][]byte) (int64, error) {
-			n, err := s.Endpoint.Peek(dsts)
-			// TODO(b/78348848): Handle peek timestamp.
-			if err != nil {
-				return int64(n), syserr.TranslateNetstackError(err).ToError()
-			}
-			return int64(n), nil
-		}})
-		n += int(num)
-		if err == syserror.ErrWouldBlock && n > 0 {
-			// We got some data, so no need to return an error.
-			err = nil
-		}
-		return n, 0, nil, 0, s.controlMessages(), syserr.FromError(err)
+		return numRead, 0, nil, 0, s.controlMessages(), nil
 	}
 
 	var msgLen int
 	if isPacket {
-		msgLen = len(s.readView)
-		s.readView = nil
+		msgLen = numTotal
 	} else {
-		msgLen = int(n)
-		s.readView.TrimFront(int(n))
-	}
-
-	if len(s.readView) == 0 {
-		atomic.StoreUint32(&s.readViewHasData, 0)
+		msgLen = numRead
 	}
 
 	var flags int
-	if msgLen > int(n) {
+	if msgLen > numRead {
 		flags |= linux.MSG_TRUNC
 	}
 
+	n := numRead
 	if trunc {
 		n = msgLen
 	}
 
 	cmsg := s.controlMessages()
 	s.fillCmsgInq(&cmsg)
-	return n, flags, addr, addrLen, cmsg, syserr.FromError(err)
+	return n, flags, addr, addrLen, cmsg, nil
 }
 
 func (s *socketOpsCommon) controlMessages() socket.ControlMessages {
@@ -3090,11 +2984,6 @@ func (s *socketOpsCommon) ioctl(ctx context.Context, io usermem.IO, args arch.Sy
 			return 0, syserr.TranslateNetstackError(terr).ToError()
 		}
 
-		// Add bytes removed from the endpoint but not yet sent to the caller.
-		s.readMu.Lock()
-		v += len(s.readView)
-		s.readMu.Unlock()
-
 		if v > math.MaxInt32 {
 			v = math.MaxInt32
 		}
diff --git a/pkg/sentry/socket/netstack/netstack_state_autogen.go b/pkg/sentry/socket/netstack/netstack_state_autogen.go
index 8465d8743..9925e2e9e 100644
--- a/pkg/sentry/socket/netstack/netstack_state_autogen.go
+++ b/pkg/sentry/socket/netstack/netstack_state_autogen.go
@@ -41,8 +41,6 @@ func (s *socketOpsCommon) StateFields() []string {
 		"Endpoint",
 		"skType",
 		"protocol",
-		"readViewHasData",
-		"readView",
 		"readCM",
 		"sender",
 		"linkPacketInfo",
@@ -63,15 +61,13 @@ func (s *socketOpsCommon) StateSave(stateSinkObject state.Sink) {
 	stateSinkObject.Save(3, &s.Endpoint)
 	stateSinkObject.Save(4, &s.skType)
 	stateSinkObject.Save(5, &s.protocol)
-	stateSinkObject.Save(6, &s.readViewHasData)
-	stateSinkObject.Save(7, &s.readView)
-	stateSinkObject.Save(8, &s.readCM)
-	stateSinkObject.Save(9, &s.sender)
-	stateSinkObject.Save(10, &s.linkPacketInfo)
-	stateSinkObject.Save(11, &s.sockOptTimestamp)
-	stateSinkObject.Save(12, &s.timestampValid)
-	stateSinkObject.Save(13, &s.timestampNS)
-	stateSinkObject.Save(14, &s.sockOptInq)
+	stateSinkObject.Save(6, &s.readCM)
+	stateSinkObject.Save(7, &s.sender)
+	stateSinkObject.Save(8, &s.linkPacketInfo)
+	stateSinkObject.Save(9, &s.sockOptTimestamp)
+	stateSinkObject.Save(10, &s.timestampValid)
+	stateSinkObject.Save(11, &s.timestampNS)
+	stateSinkObject.Save(12, &s.sockOptInq)
 }
 
 func (s *socketOpsCommon) afterLoad() {}
@@ -83,15 +79,13 @@ func (s *socketOpsCommon) StateLoad(stateSourceObject state.Source) {
 	stateSourceObject.Load(3, &s.Endpoint)
 	stateSourceObject.Load(4, &s.skType)
 	stateSourceObject.Load(5, &s.protocol)
-	stateSourceObject.Load(6, &s.readViewHasData)
-	stateSourceObject.Load(7, &s.readView)
-	stateSourceObject.Load(8, &s.readCM)
-	stateSourceObject.Load(9, &s.sender)
-	stateSourceObject.Load(10, &s.linkPacketInfo)
-	stateSourceObject.Load(11, &s.sockOptTimestamp)
-	stateSourceObject.Load(12, &s.timestampValid)
-	stateSourceObject.Load(13, &s.timestampNS)
-	stateSourceObject.Load(14, &s.sockOptInq)
+	stateSourceObject.Load(6, &s.readCM)
+	stateSourceObject.Load(7, &s.sender)
+	stateSourceObject.Load(8, &s.linkPacketInfo)
+	stateSourceObject.Load(9, &s.sockOptTimestamp)
+	stateSourceObject.Load(10, &s.timestampValid)
+	stateSourceObject.Load(11, &s.timestampNS)
+	stateSourceObject.Load(12, &s.sockOptInq)
 }
 
 func (s *SocketVFS2) StateTypeName() string {
diff --git a/pkg/syserr/netstack.go b/pkg/syserr/netstack.go
index 77c3c110c..2756d4471 100644
--- a/pkg/syserr/netstack.go
+++ b/pkg/syserr/netstack.go
@@ -48,6 +48,7 @@ var (
 	ErrInvalidOptionValue    = New(tcpip.ErrInvalidOptionValue.String(), linux.EINVAL)
 	ErrBroadcastDisabled     = New(tcpip.ErrBroadcastDisabled.String(), linux.EACCES)
 	ErrNotPermittedNet       = New(tcpip.ErrNotPermitted.String(), linux.EPERM)
+	ErrBadBuffer             = New(tcpip.ErrBadBuffer.String(), linux.EFAULT)
 )
 
 var netstackErrorTranslations map[string]*Error
@@ -100,6 +101,7 @@ func init() {
 	addErrMapping(tcpip.ErrBroadcastDisabled, ErrBroadcastDisabled)
 	addErrMapping(tcpip.ErrNotPermitted, ErrNotPermittedNet)
 	addErrMapping(tcpip.ErrAddressFamilyNotSupported, ErrAddressFamilyNotSupported)
+	addErrMapping(tcpip.ErrBadBuffer, ErrBadBuffer)
 }
 
 // TranslateNetstackError converts an error from the tcpip package to a sentry
diff --git a/pkg/tcpip/adapters/gonet/gonet.go b/pkg/tcpip/adapters/gonet/gonet.go
index 4f551cd92..7193f56ad 100644
--- a/pkg/tcpip/adapters/gonet/gonet.go
+++ b/pkg/tcpip/adapters/gonet/gonet.go
@@ -286,45 +286,47 @@ type opErrorer interface {
 
 // commonRead implements the common logic between net.Conn.Read and
 // net.PacketConn.ReadFrom.
-func commonRead(ep tcpip.Endpoint, wq *waiter.Queue, deadline <-chan struct{}, addr *tcpip.FullAddress, errorer opErrorer, dontWait bool) ([]byte, error) {
+func commonRead(b []byte, ep tcpip.Endpoint, wq *waiter.Queue, deadline <-chan struct{}, addr *tcpip.FullAddress, errorer opErrorer) (int, error) {
 	select {
 	case <-deadline:
-		return nil, errorer.newOpError("read", &timeoutError{})
+		return 0, errorer.newOpError("read", &timeoutError{})
 	default:
 	}
 
-	read, _, err := ep.Read(addr)
+	w := tcpip.SliceWriter(b)
+	opts := tcpip.ReadOptions{NeedRemoteAddr: addr != nil}
+	res, err := ep.Read(&w, len(b), opts)
 
 	if err == tcpip.ErrWouldBlock {
-		if dontWait {
-			return nil, errWouldBlock
-		}
 		// Create wait queue entry that notifies a channel.
 		waitEntry, notifyCh := waiter.NewChannelEntry(nil)
 		wq.EventRegister(&waitEntry, waiter.EventIn)
 		defer wq.EventUnregister(&waitEntry)
 		for {
-			read, _, err = ep.Read(addr)
+			res, err = ep.Read(&w, len(b), opts)
 			if err != tcpip.ErrWouldBlock {
 				break
 			}
 			select {
 			case <-deadline:
-				return nil, errorer.newOpError("read", &timeoutError{})
+				return 0, errorer.newOpError("read", &timeoutError{})
 			case <-notifyCh:
 			}
 		}
 	}
 
 	if err == tcpip.ErrClosedForReceive {
-		return nil, io.EOF
+		return 0, io.EOF
 	}
 
 	if err != nil {
-		return nil, errorer.newOpError("read", errors.New(err.String()))
+		return 0, errorer.newOpError("read", errors.New(err.String()))
 	}
 
-	return read, nil
+	if addr != nil {
+		*addr = res.RemoteAddr
+	}
+	return res.Count, nil
 }
 
 // Read implements net.Conn.Read.
@@ -334,31 +336,11 @@ func (c *TCPConn) Read(b []byte) (int, error) {
 
 	deadline := c.readCancel()
 
-	numRead := 0
-	defer func() {
-		if numRead != 0 {
-			c.ep.ModerateRecvBuf(numRead)
-		}
-	}()
-	for numRead != len(b) {
-		if len(c.read) == 0 {
-			var err error
-			c.read, err = commonRead(c.ep, c.wq, deadline, nil, c, numRead != 0)
-			if err != nil {
-				if numRead != 0 {
-					return numRead, nil
-				}
-				return numRead, err
-			}
-		}
-		n := copy(b[numRead:], c.read)
-		c.read.TrimFront(n)
-		numRead += n
-		if len(c.read) == 0 {
-			c.read = nil
-		}
+	n, err := commonRead(b, c.ep, c.wq, deadline, nil, c)
+	if n != 0 {
+		c.ep.ModerateRecvBuf(n)
 	}
-	return numRead, nil
+	return n, err
 }
 
 // Write implements net.Conn.Write.
@@ -652,12 +634,11 @@ func (c *UDPConn) ReadFrom(b []byte) (int, net.Addr, error) {
 	deadline := c.readCancel()
 
 	var addr tcpip.FullAddress
-	read, err := commonRead(c.ep, c.wq, deadline, &addr, c, false)
+	n, err := commonRead(b, c.ep, c.wq, deadline, &addr, c)
 	if err != nil {
 		return 0, nil, err
 	}
-
-	return copy(b, read), fullToUDPAddr(addr), nil
+	return n, fullToUDPAddr(addr), nil
 }
 
 func (c *UDPConn) Write(b []byte) (int, error) {
diff --git a/pkg/tcpip/buffer/view.go b/pkg/tcpip/buffer/view.go
index 8db70a700..5dd1b1b6b 100644
--- a/pkg/tcpip/buffer/view.go
+++ b/pkg/tcpip/buffer/view.go
@@ -105,18 +105,18 @@ func (vv *VectorisedView) TrimFront(count int) {
 }
 
 // Read implements io.Reader.
-func (vv *VectorisedView) Read(v View) (copied int, err error) {
-	count := len(v)
+func (vv *VectorisedView) Read(b []byte) (copied int, err error) {
+	count := len(b)
 	for count > 0 && len(vv.views) > 0 {
 		if count < len(vv.views[0]) {
 			vv.size -= count
-			copy(v[copied:], vv.views[0][:count])
+			copy(b[copied:], vv.views[0][:count])
 			vv.views[0].TrimFront(count)
 			copied += count
 			return copied, nil
 		}
 		count -= len(vv.views[0])
-		copy(v[copied:], vv.views[0])
+		copy(b[copied:], vv.views[0])
 		copied += len(vv.views[0])
 		vv.removeFirst()
 	}
@@ -145,6 +145,35 @@ func (vv *VectorisedView) ReadToVV(dstVV *VectorisedView, count int) (copied int
 	return copied
 }
 
+// ReadTo reads up to count bytes from vv to dst. It also removes them from vv
+// unless peek is true.
+func (vv *VectorisedView) ReadTo(dst io.Writer, count int, peek bool) (int, error) {
+	var err error
+	done := 0
+	for _, v := range vv.Views() {
+		remaining := count - done
+		if remaining <= 0 {
+			break
+		}
+		if len(v) > remaining {
+			v = v[:remaining]
+		}
+
+		var n int
+		n, err = dst.Write(v)
+		if n > 0 {
+			done += n
+		}
+		if err != nil {
+			break
+		}
+	}
+	if !peek {
+		vv.TrimFront(done)
+	}
+	return done, err
+}
+
 // CapLength irreversibly reduces the length of the vectorised view.
 func (vv *VectorisedView) CapLength(length int) {
 	if length < 0 {
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index ef0f51f1a..f798056c0 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -31,6 +31,7 @@ package tcpip
 import (
 	"errors"
 	"fmt"
+	"io"
 	"math/bits"
 	"reflect"
 	"strconv"
@@ -39,7 +40,6 @@ import (
 	"time"
 
 	"gvisor.dev/gvisor/pkg/sync"
-	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
@@ -113,6 +113,7 @@ var (
 	ErrNotPermitted              = &Error{msg: "operation not permitted"}
 	ErrAddressFamilyNotSupported = &Error{msg: "address family not supported by protocol"}
 	ErrMalformedHeader           = &Error{msg: "header is malformed"}
+	ErrBadBuffer                 = &Error{msg: "bad buffer"}
 )
 
 var messageToError map[string]*Error
@@ -162,6 +163,7 @@ func StringToError(s string) *Error {
 			ErrNotPermitted,
 			ErrAddressFamilyNotSupported,
 			ErrMalformedHeader,
+			ErrBadBuffer,
 		}
 
 		messageToError = make(map[string]*Error)
@@ -496,6 +498,21 @@ func (s SlicePayload) Payload(size int) ([]byte, *Error) {
 	return s[:size], nil
 }
 
+var _ io.Writer = (*SliceWriter)(nil)
+
+// SliceWriter implements io.Writer for slices.
+type SliceWriter []byte
+
+// Write implements io.Writer.Write.
+func (s *SliceWriter) Write(b []byte) (int, error) {
+	n := copy(*s, b)
+	*s = (*s)[n:]
+	if n < len(b) {
+		return n, io.ErrShortWrite
+	}
+	return n, nil
+}
+
 // A ControlMessages contains socket control messages for IP sockets.
 //
 // +stateify savable
@@ -552,6 +569,40 @@ type PacketOwner interface {
 	GID() uint32
 }
 
+// ReadOptions contains options for Endpoint.Read.
+type ReadOptions struct {
+	// Peek indicates whether this read is a peek.
+	Peek bool
+
+	// NeedRemoteAddr indicates whether to return the remote address, if
+	// supported.
+	NeedRemoteAddr bool
+
+	// NeedLinkPacketInfo indicates whether to return the link-layer information,
+	// if supported.
+	NeedLinkPacketInfo bool
+}
+
+// ReadResult represents result for a successful Endpoint.Read.
+type ReadResult struct {
+	// Count is the number of bytes received and written to the buffer.
+	Count int
+
+	// Total is the number of bytes of the received packet. This can be used to
+	// determine whether the read is truncated.
+	Total int
+
+	// ControlMessages is the control messages received.
+	ControlMessages ControlMessages
+
+	// RemoteAddr is the remote address if ReadOptions.NeedAddr is true.
+	RemoteAddr FullAddress
+
+	// LinkPacketInfo is the link-layer information of the received packet if
+	// ReadOptions.NeedLinkPacketInfo is true.
+	LinkPacketInfo LinkPacketInfo
+}
+
 // Endpoint is the interface implemented by transport protocols (e.g., tcp, udp)
 // that exposes functionality like read, write, connect, etc. to users of the
 // networking stack.
@@ -566,11 +617,15 @@ type Endpoint interface {
 	// Abort is best effort; implementing Abort with Close is acceptable.
 	Abort()
 
-	// Read reads data from the endpoint and optionally returns the sender.
+	// Read reads data from the endpoint and optionally writes to dst.
+	//
+	// This method does not block if there is no data pending; in this case,
+	// ErrWouldBlock is returned.
 	//
-	// This method does not block if there is no data pending. It will also
-	// either return an error or data, never both.
-	Read(*FullAddress) (buffer.View, ControlMessages, *Error)
+	// If non-zero number of bytes are successfully read and written to dst, err
+	// must be nil. Otherwise, if dst failed to write anything, ErrBadBuffer
+	// should be returned.
+	Read(dst io.Writer, count int, opts ReadOptions) (res ReadResult, err *Error)
 
 	// Write writes data to the endpoint's peer. This method does not block if
 	// the data cannot be written.
@@ -592,11 +647,6 @@ type Endpoint interface {
 	// not). The channel is only non-nil in this case.
 	Write(Payloader, WriteOptions) (int64, <-chan struct{}, *Error)
 
-	// Peek reads data without consuming it from the endpoint.
-	//
-	// This method does not block if there is no data pending.
-	Peek([][]byte) (int64, *Error)
-
 	// Connect connects the endpoint to its peer. Specifying a NIC is
 	// optional.
 	//
@@ -703,17 +753,6 @@ type LinkPacketInfo struct {
 	PktType PacketType
 }
 
-// PacketEndpoint are additional methods that are only implemented by Packet
-// endpoints.
-type PacketEndpoint interface {
-	// ReadPacket reads a datagram/packet from the endpoint and optionally
-	// returns the sender and additional LinkPacketInfo.
-	//
-	// This method does not block if there is no data pending. It will also
-	// either return an error or data, never both.
-	ReadPacket(*FullAddress, *LinkPacketInfo) (buffer.View, ControlMessages, *Error)
-}
-
 // EndpointInfo is the interface implemented by each endpoint info struct.
 type EndpointInfo interface {
 	// IsEndpointInfo is an empty method to implement the tcpip.EndpointInfo
diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index d1e4a7cb7..2eb4457df 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -15,6 +15,8 @@
 package icmp
 
 import (
+	"io"
+
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
@@ -151,9 +153,8 @@ func (e *endpoint) SetOwner(owner tcpip.PacketOwner) {
 	e.owner = owner
 }
 
-// Read reads data from the endpoint. This method does not block if
-// there is no data pending.
-func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+// Read implements tcpip.Endpoint.Read.
+func (e *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
 	e.rcvMu.Lock()
 
 	if e.rcvList.Empty() {
@@ -163,20 +164,34 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 			err = tcpip.ErrClosedForReceive
 		}
 		e.rcvMu.Unlock()
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	p := e.rcvList.Front()
-	e.rcvList.Remove(p)
-	e.rcvBufSize -= p.data.Size()
+	if !opts.Peek {
+		e.rcvList.Remove(p)
+		e.rcvBufSize -= p.data.Size()
+	}
 
 	e.rcvMu.Unlock()
 
-	if addr != nil {
-		*addr = p.senderAddress
+	res := tcpip.ReadResult{
+		Total: p.data.Size(),
+		ControlMessages: tcpip.ControlMessages{
+			HasTimestamp: true,
+			Timestamp:    p.timestamp,
+		},
+	}
+	if opts.NeedRemoteAddr {
+		res.RemoteAddr = p.senderAddress
 	}
 
-	return p.data.ToView(), tcpip.ControlMessages{HasTimestamp: true, Timestamp: p.timestamp}, nil
+	n, err := p.data.ReadTo(dst, count, opts.Peek)
+	if n == 0 && err != nil {
+		return res, tcpip.ErrBadBuffer
+	}
+	res.Count = n
+	return res, nil
 }
 
 // prepareForWrite prepares the endpoint for sending data. In particular, it
@@ -329,11 +344,6 @@ func (e *endpoint) write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-c
 	return int64(len(v)), nil, nil
 }
 
-// Peek only returns data from a single datagram, so do nothing here.
-func (e *endpoint) Peek([][]byte) (int64, *tcpip.Error) {
-	return 0, nil
-}
-
 // SetSockOpt sets a socket option.
 func (e *endpoint) SetSockOpt(opt tcpip.SettableSocketOption) *tcpip.Error {
 	return nil
diff --git a/pkg/tcpip/transport/packet/endpoint.go b/pkg/tcpip/transport/packet/endpoint.go
index e5e247342..3ab060751 100644
--- a/pkg/tcpip/transport/packet/endpoint.go
+++ b/pkg/tcpip/transport/packet/endpoint.go
@@ -26,6 +26,7 @@ package packet
 
 import (
 	"fmt"
+	"io"
 
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -160,8 +161,8 @@ func (ep *endpoint) Close() {
 // ModerateRecvBuf implements tcpip.Endpoint.ModerateRecvBuf.
 func (ep *endpoint) ModerateRecvBuf(copied int) {}
 
-// Read implements tcpip.PacketEndpoint.ReadPacket.
-func (ep *endpoint) ReadPacket(addr *tcpip.FullAddress, info *tcpip.LinkPacketInfo) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+// Read implements tcpip.Endpoint.Read.
+func (ep *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
 	ep.rcvMu.Lock()
 
 	// If there's no data to read, return that read would block or that the
@@ -173,29 +174,37 @@ func (ep *endpoint) ReadPacket(addr *tcpip.FullAddress, info *tcpip.LinkPacketIn
 			err = tcpip.ErrClosedForReceive
 		}
 		ep.rcvMu.Unlock()
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	packet := ep.rcvList.Front()
-	ep.rcvList.Remove(packet)
-	ep.rcvBufSize -= packet.data.Size()
+	if !opts.Peek {
+		ep.rcvList.Remove(packet)
+		ep.rcvBufSize -= packet.data.Size()
+	}
 
 	ep.rcvMu.Unlock()
 
-	if addr != nil {
-		*addr = packet.senderAddr
+	res := tcpip.ReadResult{
+		Total: packet.data.Size(),
+		ControlMessages: tcpip.ControlMessages{
+			HasTimestamp: true,
+			Timestamp:    packet.timestampNS,
+		},
 	}
-
-	if info != nil {
-		*info = packet.packetInfo
+	if opts.NeedRemoteAddr {
+		res.RemoteAddr = packet.senderAddr
+	}
+	if opts.NeedLinkPacketInfo {
+		res.LinkPacketInfo = packet.packetInfo
 	}
 
-	return packet.data.ToView(), tcpip.ControlMessages{HasTimestamp: true, Timestamp: packet.timestampNS}, nil
-}
-
-// Read implements tcpip.Endpoint.Read.
-func (ep *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
-	return ep.ReadPacket(addr, nil)
+	n, err := packet.data.ReadTo(dst, count, opts.Peek)
+	if n == 0 && err != nil {
+		return res, tcpip.ErrBadBuffer
+	}
+	res.Count = n
+	return res, nil
 }
 
 func (*endpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-chan struct{}, *tcpip.Error) {
@@ -203,11 +212,6 @@ func (*endpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-cha
 	return 0, nil, tcpip.ErrInvalidOptionValue
 }
 
-// Peek implements tcpip.Endpoint.Peek.
-func (*endpoint) Peek([][]byte) (int64, *tcpip.Error) {
-	return 0, nil
-}
-
 // Disconnect implements tcpip.Endpoint.Disconnect. Packet sockets cannot be
 // disconnected, and this function always returns tpcip.ErrNotSupported.
 func (*endpoint) Disconnect() *tcpip.Error {
diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go
index 7befcfc9b..dd260535f 100644
--- a/pkg/tcpip/transport/raw/endpoint.go
+++ b/pkg/tcpip/transport/raw/endpoint.go
@@ -27,6 +27,7 @@ package raw
 
 import (
 	"fmt"
+	"io"
 
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -190,7 +191,7 @@ func (e *endpoint) SetOwner(owner tcpip.PacketOwner) {
 }
 
 // Read implements tcpip.Endpoint.Read.
-func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+func (e *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
 	e.rcvMu.Lock()
 
 	// If there's no data to read, return that read would block or that the
@@ -202,20 +203,34 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 			err = tcpip.ErrClosedForReceive
 		}
 		e.rcvMu.Unlock()
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	pkt := e.rcvList.Front()
-	e.rcvList.Remove(pkt)
-	e.rcvBufSize -= pkt.data.Size()
+	if !opts.Peek {
+		e.rcvList.Remove(pkt)
+		e.rcvBufSize -= pkt.data.Size()
+	}
 
 	e.rcvMu.Unlock()
 
-	if addr != nil {
-		*addr = pkt.senderAddr
+	res := tcpip.ReadResult{
+		Total: pkt.data.Size(),
+		ControlMessages: tcpip.ControlMessages{
+			HasTimestamp: true,
+			Timestamp:    pkt.timestampNS,
+		},
+	}
+	if opts.NeedRemoteAddr {
+		res.RemoteAddr = pkt.senderAddr
 	}
 
-	return pkt.data.ToView(), tcpip.ControlMessages{HasTimestamp: true, Timestamp: pkt.timestampNS}, nil
+	n, err := pkt.data.ReadTo(dst, count, opts.Peek)
+	if n == 0 && err != nil {
+		return res, tcpip.ErrBadBuffer
+	}
+	res.Count = n
+	return res, nil
 }
 
 // Write implements tcpip.Endpoint.Write.
@@ -363,11 +378,6 @@ func (e *endpoint) finishWrite(payloadBytes []byte, route *stack.Route) (int64,
 	return int64(len(payloadBytes)), nil, nil
 }
 
-// Peek implements tcpip.Endpoint.Peek.
-func (e *endpoint) Peek([][]byte) (int64, *tcpip.Error) {
-	return 0, nil
-}
-
 // Disconnect implements tcpip.Endpoint.Disconnect.
 func (*endpoint) Disconnect() *tcpip.Error {
 	return tcpip.ErrNotSupported
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 6e3c8860e..8f3981075 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -17,6 +17,7 @@ package tcp
 import (
 	"encoding/binary"
 	"fmt"
+	"io"
 	"math"
 	"runtime"
 	"strings"
@@ -27,7 +28,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sleep"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
-	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip/hash/jenkins"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/ports"
@@ -393,15 +393,28 @@ type endpoint struct {
 	lastErrorMu sync.Mutex   `state:"nosave"`
 	lastError   *tcpip.Error `state:".(string)"`
 
-	// The following fields are used to manage the receive queue. The
-	// protocol goroutine adds ready-for-delivery segments to rcvList,
-	// which are returned by Read() calls to users.
+	// rcvReadMu synchronizes calls to Read.
 	//
-	// Once the peer has closed its send side, rcvClosed is set to true
-	// to indicate to users that no more data is coming.
+	// mu and rcvListMu are temporarily released during data copying. rcvReadMu
+	// must be held during each read to ensure atomicity, so that multiple reads
+	// do not interleave.
+	//
+	// rcvReadMu should be held before holding mu.
+	rcvReadMu sync.Mutex `state:"nosave"`
+
+	// rcvListMu synchronizes access to rcvList.
 	//
 	// rcvListMu can be taken after the endpoint mu below.
-	rcvListMu sync.Mutex  `state:"nosave"`
+	rcvListMu sync.Mutex `state:"nosave"`
+
+	// rcvList is the queue for ready-for-delivery segments.
+	//
+	// rcvReadMu, mu and rcvListMu must be held, in the stated order, to read data
+	// and removing segments from list. A range of segment can be determined, then
+	// temporarily release mu and rcvListMu while processing the segment range.
+	// This allows new segments to be appended to the list while processing.
+	//
+	// rcvListMu must be held to append segments to list.
 	rcvList   segmentList `state:"wait"`
 	rcvClosed bool
 	// rcvBufSize is the total size of the receive buffer.
@@ -1309,8 +1322,69 @@ func (e *endpoint) UpdateLastError(err *tcpip.Error) {
 	e.UnlockUser()
 }
 
-// Read reads data from the endpoint.
-func (e *endpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+// Read implements tcpip.Endpoint.Read.
+func (e *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
+	e.rcvReadMu.Lock()
+	defer e.rcvReadMu.Unlock()
+
+	// N.B. Here we get a range of segments to be processed. It is safe to not
+	// hold rcvListMu when processing, since we hold rcvReadMu to ensure only we
+	// can remove segments from the list through commitRead().
+	first, last, serr := e.startRead()
+	if serr != nil {
+		if serr == tcpip.ErrClosedForReceive {
+			e.stats.ReadErrors.ReadClosed.Increment()
+		}
+		return tcpip.ReadResult{}, serr
+	}
+
+	var err error
+	done := 0
+	s := first
+	for s != nil && done < count {
+		var n int
+		n, err = s.data.ReadTo(dst, count-done, opts.Peek)
+		// Book keeping first then error handling.
+
+		done += n
+
+		if opts.Peek {
+			// For peek, we use the (first, last) range of segment returned from
+			// startRead. We don't consume the receive buffer, so commitRead should
+			// not be called.
+			//
+			// N.B. It is important to use `last` to determine the last segment, since
+			// appending can happen while we process, and will lead to data race.
+			if s == last {
+				break
+			}
+			s = s.Next()
+		} else {
+			// N.B. commitRead() conveniently returns the next segment to read, after
+			// removing the data/segment that is read.
+			s = e.commitRead(n)
+		}
+
+		if err != nil {
+			break
+		}
+	}
+
+	// If something is read, we must report it. Report error when nothing is read.
+	if done == 0 && err != nil {
+		return tcpip.ReadResult{}, tcpip.ErrBadBuffer
+	}
+	return tcpip.ReadResult{
+		Count: done,
+		Total: done,
+	}, nil
+}
+
+// startRead checks that endpoint is in a readable state, and return the
+// inclusive range of segments that can be read.
+//
+// Precondition: e.rcvReadMu must be held.
+func (e *endpoint) startRead() (first, last *segment, err *tcpip.Error) {
 	e.LockUser()
 	defer e.UnlockUser()
 
@@ -1319,7 +1393,7 @@ func (e *endpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages,
 	// on a receive. It can expect to read any data after the handshake
 	// is complete. RFC793, section 3.9, p58.
 	if e.EndpointState() == StateSynSent {
-		return buffer.View{}, tcpip.ControlMessages{}, tcpip.ErrWouldBlock
+		return nil, nil, tcpip.ErrWouldBlock
 	}
 
 	// The endpoint can be read if it's connected, or if it's already closed
@@ -1327,61 +1401,69 @@ func (e *endpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages,
 	// would cause the state to become StateError so we should allow the
 	// reads to proceed before returning a ECONNRESET.
 	e.rcvListMu.Lock()
+	defer e.rcvListMu.Unlock()
+
 	bufUsed := e.rcvBufUsed
 	if s := e.EndpointState(); !s.connected() && s != StateClose && bufUsed == 0 {
-		e.rcvListMu.Unlock()
 		if s == StateError {
 			if err := e.hardErrorLocked(); err != nil {
-				return buffer.View{}, tcpip.ControlMessages{}, err
+				return nil, nil, err
 			}
-			return buffer.View{}, tcpip.ControlMessages{}, tcpip.ErrClosedForReceive
+			return nil, nil, tcpip.ErrClosedForReceive
 		}
 		e.stats.ReadErrors.NotConnected.Increment()
-		return buffer.View{}, tcpip.ControlMessages{}, tcpip.ErrNotConnected
+		return nil, nil, tcpip.ErrNotConnected
 	}
 
-	v, err := e.readLocked()
-	e.rcvListMu.Unlock()
-
-	if err == tcpip.ErrClosedForReceive {
-		e.stats.ReadErrors.ReadClosed.Increment()
-	}
-	return v, tcpip.ControlMessages{}, err
-}
-
-func (e *endpoint) readLocked() (buffer.View, *tcpip.Error) {
 	if e.rcvBufUsed == 0 {
 		if e.rcvClosed || !e.EndpointState().connected() {
-			return buffer.View{}, tcpip.ErrClosedForReceive
+			return nil, nil, tcpip.ErrClosedForReceive
 		}
-		return buffer.View{}, tcpip.ErrWouldBlock
+		return nil, nil, tcpip.ErrWouldBlock
 	}
 
-	s := e.rcvList.Front()
-	views := s.data.Views()
-	v := views[s.viewToDeliver]
-	s.viewToDeliver++
+	return e.rcvList.Front(), e.rcvList.Back(), nil
+}
+
+// commitRead commits a read of done bytes and returns the next non-empty
+// segment to read. Data read from the segment must have also been removed from
+// the segment in order for this method to work correctly.
+//
+// It is performance critical to call commitRead frequently when servicing a big
+// Read request, so TCP can make progress timely. Right now, it is designed to
+// do this per segment read, hence this method conveniently returns the next
+// segment to read while holding the lock.
+//
+// Precondition: e.rcvReadMu must be held.
+func (e *endpoint) commitRead(done int) *segment {
+	e.LockUser()
+	defer e.UnlockUser()
+	e.rcvListMu.Lock()
+	defer e.rcvListMu.Unlock()
 
-	var delta int
-	if s.viewToDeliver >= len(views) {
+	memDelta := 0
+	s := e.rcvList.Front()
+	for s != nil && s.data.Size() == 0 {
 		e.rcvList.Remove(s)
-		// We only free up receive buffer space when the segment is released as the
-		// segment is still holding on to the views even though some views have been
-		// read out to the user.
-		delta = s.segMemSize()
+		// Memory is only considered released when the whole segment has been
+		// read.
+		memDelta += s.segMemSize()
 		s.decRef()
+		s = e.rcvList.Front()
 	}
+	e.rcvBufUsed -= done
 
-	e.rcvBufUsed -= len(v)
-	// If the window was small before this read and if the read freed up
-	// enough buffer space, to either fit an aMSS or half a receive buffer
-	// (whichever smaller), then notify the protocol goroutine to send a
-	// window update.
-	if crossed, above := e.windowCrossedACKThresholdLocked(delta); crossed && above {
-		e.notifyProtocolGoroutine(notifyNonZeroReceiveWindow)
+	if memDelta > 0 {
+		// If the window was small before this read and if the read freed up
+		// enough buffer space, to either fit an aMSS or half a receive buffer
+		// (whichever smaller), then notify the protocol goroutine to send a
+		// window update.
+		if crossed, above := e.windowCrossedACKThresholdLocked(memDelta); crossed && above {
+			e.notifyProtocolGoroutine(notifyNonZeroReceiveWindow)
+		}
 	}
 
-	return v, nil
+	return e.rcvList.Front()
 }
 
 // isEndpointWritableLocked checks if a given endpoint is writable
@@ -1499,64 +1581,6 @@ func (e *endpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-c
 	return queueAndSend()
 }
 
-// Peek reads data without consuming it from the endpoint.
-//
-// This method does not block if there is no data pending.
-func (e *endpoint) Peek(vec [][]byte) (int64, *tcpip.Error) {
-	e.LockUser()
-	defer e.UnlockUser()
-
-	// The endpoint can be read if it's connected, or if it's already closed
-	// but has some pending unread data.
-	if s := e.EndpointState(); !s.connected() && s != StateClose {
-		if s == StateError {
-			return 0, e.hardErrorLocked()
-		}
-		e.stats.ReadErrors.InvalidEndpointState.Increment()
-		return 0, tcpip.ErrInvalidEndpointState
-	}
-
-	e.rcvListMu.Lock()
-	defer e.rcvListMu.Unlock()
-
-	if e.rcvBufUsed == 0 {
-		if e.rcvClosed || !e.EndpointState().connected() {
-			e.stats.ReadErrors.ReadClosed.Increment()
-			return 0, tcpip.ErrClosedForReceive
-		}
-		return 0, tcpip.ErrWouldBlock
-	}
-
-	// Make a copy of vec so we can modify the slide headers.
-	vec = append([][]byte(nil), vec...)
-
-	var num int64
-	for s := e.rcvList.Front(); s != nil; s = s.Next() {
-		views := s.data.Views()
-
-		for i := s.viewToDeliver; i < len(views); i++ {
-			v := views[i]
-
-			for len(v) > 0 {
-				if len(vec) == 0 {
-					return num, nil
-				}
-				if len(vec[0]) == 0 {
-					vec = vec[1:]
-					continue
-				}
-
-				n := copy(vec[0], v)
-				v = v[n:]
-				vec[0] = vec[0][n:]
-				num += int64(n)
-			}
-		}
-	}
-
-	return num, nil
-}
-
 // selectWindowLocked returns the new window without checking for shrinking or scaling
 // applied.
 // Precondition: e.mu and e.rcvListMu must be held.
diff --git a/pkg/tcpip/transport/tcp/segment.go b/pkg/tcpip/transport/tcp/segment.go
index 5ef73ec74..c5a6d2fba 100644
--- a/pkg/tcpip/transport/tcp/segment.go
+++ b/pkg/tcpip/transport/tcp/segment.go
@@ -37,7 +37,7 @@ const (
 
 // segment represents a TCP segment. It holds the payload and parsed TCP segment
 // information, and can be added to intrusive lists.
-// segment is mostly immutable, the only field allowed to change is viewToDeliver.
+// segment is mostly immutable, the only field allowed to change is data.
 //
 // +stateify savable
 type segment struct {
@@ -60,10 +60,7 @@ type segment struct {
 	hdr header.TCP
 	// views is used as buffer for data when its length is large
 	// enough to store a VectorisedView.
-	views [8]buffer.View `state:"nosave"`
-	// viewToDeliver keeps track of the next View that should be
-	// delivered by the Read endpoint.
-	viewToDeliver  int
+	views          [8]buffer.View `state:"nosave"`
 	sequenceNumber seqnum.Value
 	ackNumber      seqnum.Value
 	flags          uint8
@@ -84,6 +81,9 @@ type segment struct {
 
 	// acked indicates if the segment has already been SACKed.
 	acked bool
+
+	// dataMemSize is the memory used by data initially.
+	dataMemSize int
 }
 
 func newIncomingSegment(id stack.TransportEndpointID, pkt *stack.PacketBuffer) *segment {
@@ -100,6 +100,7 @@ func newIncomingSegment(id stack.TransportEndpointID, pkt *stack.PacketBuffer) *
 	s.data = pkt.Data.Clone(s.views[:])
 	s.hdr = header.TCP(pkt.TransportHeader().View())
 	s.rcvdTime = time.Now()
+	s.dataMemSize = s.data.Size()
 	return s
 }
 
@@ -113,6 +114,7 @@ func newOutgoingSegment(id stack.TransportEndpointID, v buffer.View) *segment {
 		s.views[0] = v
 		s.data = buffer.NewVectorisedView(len(v), s.views[:1])
 	}
+	s.dataMemSize = s.data.Size()
 	return s
 }
 
@@ -127,12 +129,12 @@ func (s *segment) clone() *segment {
 		netProto:       s.netProto,
 		nicID:          s.nicID,
 		remoteLinkAddr: s.remoteLinkAddr,
-		viewToDeliver:  s.viewToDeliver,
 		rcvdTime:       s.rcvdTime,
 		xmitTime:       s.xmitTime,
 		xmitCount:      s.xmitCount,
 		ep:             s.ep,
 		qFlags:         s.qFlags,
+		dataMemSize:    s.dataMemSize,
 	}
 	t.data = s.data.Clone(t.views[:])
 	return t
@@ -204,7 +206,7 @@ func (s *segment) payloadSize() int {
 // segMemSize is the amount of memory used to hold the segment data and
 // the associated metadata.
 func (s *segment) segMemSize() int {
-	return SegSize + s.data.Size()
+	return SegSize + s.dataMemSize
 }
 
 // parse populates the sequence & ack numbers, flags, and window fields of the
diff --git a/pkg/tcpip/transport/tcp/segment_state.go b/pkg/tcpip/transport/tcp/segment_state.go
index 7dc2741a6..7422d8c02 100644
--- a/pkg/tcpip/transport/tcp/segment_state.go
+++ b/pkg/tcpip/transport/tcp/segment_state.go
@@ -24,16 +24,11 @@ import (
 func (s *segment) saveData() buffer.VectorisedView {
 	// We cannot save s.data directly as s.data.views may alias to s.views,
 	// which is not allowed by state framework (in-struct pointer).
-	v := make([]buffer.View, len(s.data.Views()))
-	// For views already delivered, we cannot save them directly as they may
-	// have already been sliced and saved elsewhere (e.g., readViews).
-	for i := 0; i < s.viewToDeliver; i++ {
-		v[i] = append([]byte(nil), s.data.Views()[i]...)
+	vs := make([]buffer.View, len(s.data.Views()))
+	for i, v := range s.data.Views() {
+		vs[i] = v
 	}
-	for i := s.viewToDeliver; i < len(v); i++ {
-		v[i] = s.data.Views()[i]
-	}
-	return buffer.NewVectorisedView(s.data.Size(), v)
+	return buffer.NewVectorisedView(s.data.Size(), vs)
 }
 
 // loadData is invoked by stateify.
diff --git a/pkg/tcpip/transport/tcp/tcp_state_autogen.go b/pkg/tcpip/transport/tcp/tcp_state_autogen.go
index 5922083a9..aab92b94f 100644
--- a/pkg/tcpip/transport/tcp/tcp_state_autogen.go
+++ b/pkg/tcpip/transport/tcp/tcp_state_autogen.go
@@ -595,7 +595,6 @@ func (s *segment) StateFields() []string {
 		"remoteLinkAddr",
 		"data",
 		"hdr",
-		"viewToDeliver",
 		"sequenceNumber",
 		"ackNumber",
 		"flags",
@@ -609,6 +608,7 @@ func (s *segment) StateFields() []string {
 		"xmitTime",
 		"xmitCount",
 		"acked",
+		"dataMemSize",
 	}
 }
 
@@ -619,11 +619,11 @@ func (s *segment) StateSave(stateSinkObject state.Sink) {
 	var dataValue buffer.VectorisedView = s.saveData()
 	stateSinkObject.SaveValue(9, dataValue)
 	var optionsValue []byte = s.saveOptions()
-	stateSinkObject.SaveValue(19, optionsValue)
+	stateSinkObject.SaveValue(18, optionsValue)
 	var rcvdTimeValue unixTime = s.saveRcvdTime()
-	stateSinkObject.SaveValue(21, rcvdTimeValue)
+	stateSinkObject.SaveValue(20, rcvdTimeValue)
 	var xmitTimeValue unixTime = s.saveXmitTime()
-	stateSinkObject.SaveValue(22, xmitTimeValue)
+	stateSinkObject.SaveValue(21, xmitTimeValue)
 	stateSinkObject.Save(0, &s.segmentEntry)
 	stateSinkObject.Save(1, &s.refCnt)
 	stateSinkObject.Save(2, &s.ep)
@@ -634,17 +634,17 @@ func (s *segment) StateSave(stateSinkObject state.Sink) {
 	stateSinkObject.Save(7, &s.nicID)
 	stateSinkObject.Save(8, &s.remoteLinkAddr)
 	stateSinkObject.Save(10, &s.hdr)
-	stateSinkObject.Save(11, &s.viewToDeliver)
-	stateSinkObject.Save(12, &s.sequenceNumber)
-	stateSinkObject.Save(13, &s.ackNumber)
-	stateSinkObject.Save(14, &s.flags)
-	stateSinkObject.Save(15, &s.window)
-	stateSinkObject.Save(16, &s.csum)
-	stateSinkObject.Save(17, &s.csumValid)
-	stateSinkObject.Save(18, &s.parsedOptions)
-	stateSinkObject.Save(20, &s.hasNewSACKInfo)
-	stateSinkObject.Save(23, &s.xmitCount)
-	stateSinkObject.Save(24, &s.acked)
+	stateSinkObject.Save(11, &s.sequenceNumber)
+	stateSinkObject.Save(12, &s.ackNumber)
+	stateSinkObject.Save(13, &s.flags)
+	stateSinkObject.Save(14, &s.window)
+	stateSinkObject.Save(15, &s.csum)
+	stateSinkObject.Save(16, &s.csumValid)
+	stateSinkObject.Save(17, &s.parsedOptions)
+	stateSinkObject.Save(19, &s.hasNewSACKInfo)
+	stateSinkObject.Save(22, &s.xmitCount)
+	stateSinkObject.Save(23, &s.acked)
+	stateSinkObject.Save(24, &s.dataMemSize)
 }
 
 func (s *segment) afterLoad() {}
@@ -660,21 +660,21 @@ func (s *segment) StateLoad(stateSourceObject state.Source) {
 	stateSourceObject.Load(7, &s.nicID)
 	stateSourceObject.Load(8, &s.remoteLinkAddr)
 	stateSourceObject.Load(10, &s.hdr)
-	stateSourceObject.Load(11, &s.viewToDeliver)
-	stateSourceObject.Load(12, &s.sequenceNumber)
-	stateSourceObject.Load(13, &s.ackNumber)
-	stateSourceObject.Load(14, &s.flags)
-	stateSourceObject.Load(15, &s.window)
-	stateSourceObject.Load(16, &s.csum)
-	stateSourceObject.Load(17, &s.csumValid)
-	stateSourceObject.Load(18, &s.parsedOptions)
-	stateSourceObject.Load(20, &s.hasNewSACKInfo)
-	stateSourceObject.Load(23, &s.xmitCount)
-	stateSourceObject.Load(24, &s.acked)
+	stateSourceObject.Load(11, &s.sequenceNumber)
+	stateSourceObject.Load(12, &s.ackNumber)
+	stateSourceObject.Load(13, &s.flags)
+	stateSourceObject.Load(14, &s.window)
+	stateSourceObject.Load(15, &s.csum)
+	stateSourceObject.Load(16, &s.csumValid)
+	stateSourceObject.Load(17, &s.parsedOptions)
+	stateSourceObject.Load(19, &s.hasNewSACKInfo)
+	stateSourceObject.Load(22, &s.xmitCount)
+	stateSourceObject.Load(23, &s.acked)
+	stateSourceObject.Load(24, &s.dataMemSize)
 	stateSourceObject.LoadValue(9, new(buffer.VectorisedView), func(y interface{}) { s.loadData(y.(buffer.VectorisedView)) })
-	stateSourceObject.LoadValue(19, new([]byte), func(y interface{}) { s.loadOptions(y.([]byte)) })
-	stateSourceObject.LoadValue(21, new(unixTime), func(y interface{}) { s.loadRcvdTime(y.(unixTime)) })
-	stateSourceObject.LoadValue(22, new(unixTime), func(y interface{}) { s.loadXmitTime(y.(unixTime)) })
+	stateSourceObject.LoadValue(18, new([]byte), func(y interface{}) { s.loadOptions(y.([]byte)) })
+	stateSourceObject.LoadValue(20, new(unixTime), func(y interface{}) { s.loadRcvdTime(y.(unixTime)) })
+	stateSourceObject.LoadValue(21, new(unixTime), func(y interface{}) { s.loadXmitTime(y.(unixTime)) })
 }
 
 func (q *segmentQueue) StateTypeName() string {
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 4e8bd8b04..075de1db0 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -16,6 +16,7 @@ package udp
 
 import (
 	"fmt"
+	"io"
 	"sync/atomic"
 
 	"gvisor.dev/gvisor/pkg/sync"
@@ -282,11 +283,10 @@ func (e *endpoint) Close() {
 // ModerateRecvBuf implements tcpip.Endpoint.ModerateRecvBuf.
 func (e *endpoint) ModerateRecvBuf(copied int) {}
 
-// Read reads data from the endpoint. This method does not block if
-// there is no data pending.
-func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+// Read implements tcpip.Endpoint.Read.
+func (e *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
 	if err := e.LastError(); err != nil {
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	e.rcvMu.Lock()
@@ -298,18 +298,17 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 			err = tcpip.ErrClosedForReceive
 		}
 		e.rcvMu.Unlock()
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	p := e.rcvList.Front()
-	e.rcvList.Remove(p)
-	e.rcvBufSize -= p.data.Size()
-	e.rcvMu.Unlock()
-
-	if addr != nil {
-		*addr = p.senderAddress
+	if !opts.Peek {
+		e.rcvList.Remove(p)
+		e.rcvBufSize -= p.data.Size()
 	}
+	e.rcvMu.Unlock()
 
+	// Control Messages
 	cm := tcpip.ControlMessages{
 		HasTimestamp: true,
 		Timestamp:    p.timestamp,
@@ -331,7 +330,22 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 		cm.HasOriginalDstAddress = true
 		cm.OriginalDstAddress = p.destinationAddress
 	}
-	return p.data.ToView(), cm, nil
+
+	// Read Result
+	res := tcpip.ReadResult{
+		Total:           p.data.Size(),
+		ControlMessages: cm,
+	}
+	if opts.NeedRemoteAddr {
+		res.RemoteAddr = p.senderAddress
+	}
+
+	n, err := p.data.ReadTo(dst, count, opts.Peek)
+	if n == 0 && err != nil {
+		return res, tcpip.ErrBadBuffer
+	}
+	res.Count = n
+	return res, nil
 }
 
 // prepareForWrite prepares the endpoint for sending data. In particular, it
@@ -566,11 +580,6 @@ func (e *endpoint) write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-c
 	return int64(len(v)), nil, nil
 }
 
-// Peek only returns data from a single datagram, so do nothing here.
-func (e *endpoint) Peek([][]byte) (int64, *tcpip.Error) {
-	return 0, nil
-}
-
 // OnReuseAddressSet implements tcpip.SocketOptionsHandler.OnReuseAddressSet.
 func (e *endpoint) OnReuseAddressSet(v bool) {
 	e.mu.Lock()