net/tcp/setockopt: impelment setsockopt(fd, SOL_TCP, TCP_INQ)

PiperOrigin-RevId: 258859507

4 files changed, 96 insertions, 24 deletions

diff --git a/pkg/sentry/socket/control/control.go b/pkg/sentry/socket/control/control.go
index 4f4a20dfe..4e95101b7 100644
--- a/pkg/sentry/socket/control/control.go
+++ b/pkg/sentry/socket/control/control.go
@@ -225,14 +225,14 @@ func putCmsg(buf []byte, flags int, msgType uint32, align uint, data []int32) ([
 	return alignSlice(buf, align), flags
 }
 
-func putCmsgStruct(buf []byte, msgType uint32, align uint, data interface{}) []byte {
+func putCmsgStruct(buf []byte, msgLevel, msgType uint32, align uint, data interface{}) []byte {
 	if cap(buf)-len(buf) < linux.SizeOfControlMessageHeader {
 		return buf
 	}
 	ob := buf
 
 	buf = putUint64(buf, uint64(linux.SizeOfControlMessageHeader))
-	buf = putUint32(buf, linux.SOL_SOCKET)
+	buf = putUint32(buf, msgLevel)
 	buf = putUint32(buf, msgType)
 
 	hdrBuf := buf
@@ -307,12 +307,24 @@ func alignSlice(buf []byte, align uint) []byte {
 func PackTimestamp(t *kernel.Task, timestamp int64, buf []byte) []byte {
 	return putCmsgStruct(
 		buf,
+		linux.SOL_SOCKET,
 		linux.SO_TIMESTAMP,
 		t.Arch().Width(),
 		linux.NsecToTimeval(timestamp),
 	)
 }
 
+// PackInq packs a TCP_INQ socket control message.
+func PackInq(t *kernel.Task, inq int32, buf []byte) []byte {
+	return putCmsgStruct(
+		buf,
+		linux.SOL_TCP,
+		linux.TCP_INQ,
+		4,
+		inq,
+	)
+}
+
 // Parse parses a raw socket control message into portable objects.
 func Parse(t *kernel.Task, socketOrEndpoint interface{}, buf []byte) (transport.ControlMessages, error) {
 	var (
diff --git a/pkg/sentry/socket/epsocket/epsocket.go b/pkg/sentry/socket/epsocket/epsocket.go
index 69eff7373..e57aed927 100644
--- a/pkg/sentry/socket/epsocket/epsocket.go
+++ b/pkg/sentry/socket/epsocket/epsocket.go
@@ -207,6 +207,10 @@ type commonEndpoint interface {
 	// GetSockOpt implements tcpip.Endpoint.GetSockOpt and
 	// transport.Endpoint.GetSockOpt.
 	GetSockOpt(interface{}) *tcpip.Error
+
+	// GetSockOptInt implements tcpip.Endpoint.GetSockOptInt and
+	// transport.Endpoint.GetSockOpt.
+	GetSockOptInt(opt tcpip.SockOpt) (int, *tcpip.Error)
 }
 
 // SocketOperations encapsulates all the state needed to represent a network stack
@@ -249,6 +253,10 @@ type SocketOperations struct {
 	// timestampNS holds the timestamp to use with SIOCTSTAMP. It is only
 	// valid when timestampValid is true. It is protected by readMu.
 	timestampNS int64
+
+	// sockOptInq corresponds to TCP_INQ. It is implemented on the epsocket
+	// level, because it takes into account data from readView.
+	sockOptInq bool
 }
 
 // New creates a new endpoint socket.
@@ -634,6 +642,18 @@ func (s *SocketOperations) GetSockOpt(t *kernel.Task, level, name, outLen int) (
 		}
 		return val, nil
 	}
+	if level == linux.SOL_TCP && name == linux.TCP_INQ {
+		if outLen < sizeOfInt32 {
+			return nil, syserr.ErrInvalidArgument
+		}
+		val := int32(0)
+		s.readMu.Lock()
+		defer s.readMu.Unlock()
+		if s.sockOptInq {
+			val = 1
+		}
+		return val, nil
+	}
 
 	return GetSockOpt(t, s, s.Endpoint, s.family, s.skType, level, name, outLen)
 }
@@ -1048,6 +1068,15 @@ func (s *SocketOperations) SetSockOpt(t *kernel.Task, level int, name int, optVa
 		s.sockOptTimestamp = usermem.ByteOrder.Uint32(optVal) != 0
 		return nil
 	}
+	if level == linux.SOL_TCP && name == linux.TCP_INQ {
+		if len(optVal) < sizeOfInt32 {
+			return syserr.ErrInvalidArgument
+		}
+		s.readMu.Lock()
+		defer s.readMu.Unlock()
+		s.sockOptInq = usermem.ByteOrder.Uint32(optVal) != 0
+		return nil
+	}
 
 	return SetSockOpt(t, s, s.Endpoint, level, name, optVal)
 }
@@ -1267,6 +1296,7 @@ func setSockOptTCP(t *kernel.Task, ep commonEndpoint, name int, optVal []byte) *
 			return syserr.TranslateNetstackError(err)
 		}
 		return nil
+
 	case linux.TCP_REPAIR_OPTIONS:
 		t.Kernel().EmitUnimplementedEvent(t)
 
@@ -1492,7 +1522,6 @@ func emitUnimplementedEventTCP(t *kernel.Task, name int) {
 		linux.TCP_FASTOPEN_CONNECT,
 		linux.TCP_FASTOPEN_KEY,
 		linux.TCP_FASTOPEN_NO_COOKIE,
-		linux.TCP_INQ,
 		linux.TCP_KEEPCNT,
 		linux.TCP_KEEPIDLE,
 		linux.TCP_KEEPINTVL,
@@ -1747,6 +1776,18 @@ func (s *SocketOperations) coalescingRead(ctx context.Context, dst usermem.IOSeq
 	return 0, err
 }
 
+func (s *SocketOperations) fillCmsgInq(cmsg *socket.ControlMessages) {
+	if !s.sockOptInq {
+		return
+	}
+	rcvBufUsed, err := s.Endpoint.GetSockOptInt(tcpip.ReceiveQueueSizeOption)
+	if err != nil {
+		return
+	}
+	cmsg.IP.HasInq = true
+	cmsg.IP.Inq = int32(len(s.readView) + rcvBufUsed)
+}
+
 // nonBlockingRead issues a non-blocking read.
 //
 // TODO(b/78348848): Support timestamps for stream sockets.
@@ -1766,7 +1807,9 @@ func (s *SocketOperations) nonBlockingRead(ctx context.Context, dst usermem.IOSe
 		s.readMu.Lock()
 		n, err := s.coalescingRead(ctx, dst, trunc)
 		s.readMu.Unlock()
-		return n, 0, nil, 0, socket.ControlMessages{}, err
+		cmsg := s.controlMessages()
+		s.fillCmsgInq(&cmsg)
+		return n, 0, nil, 0, cmsg, err
 	}
 
 	s.readMu.Lock()
@@ -1779,8 +1822,8 @@ func (s *SocketOperations) nonBlockingRead(ctx context.Context, dst usermem.IOSe
 	if !isPacket && peek && trunc {
 		// MSG_TRUNC with MSG_PEEK on a TCP socket returns the
 		// amount that could be read.
-		var rql tcpip.ReceiveQueueSizeOption
-		if err := s.Endpoint.GetSockOpt(&rql); err != nil {
+		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)
@@ -1848,7 +1891,9 @@ func (s *SocketOperations) nonBlockingRead(ctx context.Context, dst usermem.IOSe
 		n = msgLen
 	}
 
-	return n, flags, addr, addrLen, s.controlMessages(), syserr.FromError(err)
+	cmsg := s.controlMessages()
+	s.fillCmsgInq(&cmsg)
+	return n, flags, addr, addrLen, cmsg, syserr.FromError(err)
 }
 
 func (s *SocketOperations) controlMessages() socket.ControlMessages {
@@ -2086,9 +2131,9 @@ func Ioctl(ctx context.Context, ep commonEndpoint, io usermem.IO, args arch.Sysc
 		return 0, err
 
 	case linux.TIOCINQ:
-		var v tcpip.ReceiveQueueSizeOption
-		if err := ep.GetSockOpt(&v); err != nil {
-			return 0, syserr.TranslateNetstackError(err).ToError()
+		v, terr := ep.GetSockOptInt(tcpip.ReceiveQueueSizeOption)
+		if terr != nil {
+			return 0, syserr.TranslateNetstackError(terr).ToError()
 		}
 
 		if v > math.MaxInt32 {
diff --git a/pkg/sentry/socket/unix/transport/unix.go b/pkg/sentry/socket/unix/transport/unix.go
index b0765ba55..7fb9cb1e0 100644
--- a/pkg/sentry/socket/unix/transport/unix.go
+++ b/pkg/sentry/socket/unix/transport/unix.go
@@ -179,6 +179,10 @@ type Endpoint interface {
 	// tcpip.*Option types.
 	GetSockOpt(opt interface{}) *tcpip.Error
 
+	// GetSockOptInt gets a socket option for simple cases when a return
+	// value has the int type.
+	GetSockOptInt(opt tcpip.SockOpt) (int, *tcpip.Error)
+
 	// State returns the current state of the socket, as represented by Linux in
 	// procfs.
 	State() uint32
@@ -834,33 +838,39 @@ func (e *baseEndpoint) SetSockOpt(opt interface{}) *tcpip.Error {
 	return nil
 }
 
-// GetSockOpt implements tcpip.Endpoint.GetSockOpt.
-func (e *baseEndpoint) GetSockOpt(opt interface{}) *tcpip.Error {
-	switch o := opt.(type) {
-	case tcpip.ErrorOption:
-		return nil
-
-	case *tcpip.SendQueueSizeOption:
+func (e *baseEndpoint) GetSockOptInt(opt tcpip.SockOpt) (int, *tcpip.Error) {
+	switch opt {
+	case tcpip.ReceiveQueueSizeOption:
+		v := 0
 		e.Lock()
 		if !e.Connected() {
 			e.Unlock()
-			return tcpip.ErrNotConnected
+			return -1, tcpip.ErrNotConnected
 		}
-		qs := tcpip.SendQueueSizeOption(e.connected.SendQueuedSize())
+		v = int(e.receiver.RecvQueuedSize())
 		e.Unlock()
-		if qs < 0 {
-			return tcpip.ErrQueueSizeNotSupported
+		if v < 0 {
+			return -1, tcpip.ErrQueueSizeNotSupported
 		}
-		*o = qs
+		return v, nil
+	default:
+		return -1, tcpip.ErrUnknownProtocolOption
+	}
+}
+
+// GetSockOpt implements tcpip.Endpoint.GetSockOpt.
+func (e *baseEndpoint) GetSockOpt(opt interface{}) *tcpip.Error {
+	switch o := opt.(type) {
+	case tcpip.ErrorOption:
 		return nil
 
-	case *tcpip.ReceiveQueueSizeOption:
+	case *tcpip.SendQueueSizeOption:
 		e.Lock()
 		if !e.Connected() {
 			e.Unlock()
 			return tcpip.ErrNotConnected
 		}
-		qs := tcpip.ReceiveQueueSizeOption(e.receiver.RecvQueuedSize())
+		qs := tcpip.SendQueueSizeOption(e.connected.SendQueuedSize())
 		e.Unlock()
 		if qs < 0 {
 			return tcpip.ErrQueueSizeNotSupported
diff --git a/pkg/sentry/syscalls/linux/sys_socket.go b/pkg/sentry/syscalls/linux/sys_socket.go
index 195734257..fa568a660 100644
--- a/pkg/sentry/syscalls/linux/sys_socket.go
+++ b/pkg/sentry/syscalls/linux/sys_socket.go
@@ -802,6 +802,11 @@ func recvSingleMsg(t *kernel.Task, s socket.Socket, msgPtr usermem.Addr, flags i
 		controlData = control.PackTimestamp(t, cms.IP.Timestamp, controlData)
 	}
 
+	if cms.IP.HasInq {
+		// In Linux, TCP_CM_INQ is added after SO_TIMESTAMP.
+		controlData = control.PackInq(t, cms.IP.Inq, controlData)
+	}
+
 	if cms.Unix.Rights != nil {
 		controlData, mflags = control.PackRights(t, cms.Unix.Rights.(control.SCMRights), flags&linux.MSG_CMSG_CLOEXEC != 0, controlData, mflags)
 	}