Move SO_SNDBUF to socketops.

This CL moves {S,G}etsockopt of SO_SNDBUF from all endpoints to socketops. For
unix sockets, we do not support setting of this option.

PiperOrigin-RevId: 353871484

17 files changed, 203 insertions, 196 deletions

diff --git a/pkg/tcpip/socketops.go b/pkg/tcpip/socketops.go
index f3ad40fdf..4149b91da 100644
--- a/pkg/tcpip/socketops.go
+++ b/pkg/tcpip/socketops.go
@@ -15,11 +15,16 @@
 package tcpip
 
 import (
+	"math"
 	"sync/atomic"
 
 	"gvisor.dev/gvisor/pkg/sync"
 )
 
+// PacketOverheadFactor is used to multiply the value provided by the user on a
+// SetSockOpt for setting the send/receive buffer sizes sockets.
+const PacketOverheadFactor = 2
+
 // SocketOptionsHandler holds methods that help define endpoint specific
 // behavior for socket level socket options. These must be implemented by
 // endpoints to get notified when socket level options are set.
@@ -48,6 +53,12 @@ type SocketOptionsHandler interface {
 
 	// HasNIC is invoked to check if the NIC is valid for SO_BINDTODEVICE.
 	HasNIC(v int32) bool
+
+	// GetSendBufferSize is invoked to get the SO_SNDBUFSIZE.
+	GetSendBufferSize() (int64, *Error)
+
+	// IsUnixSocket is invoked to check if the socket is of unix domain.
+	IsUnixSocket() bool
 }
 
 // DefaultSocketOptionsHandler is an embeddable type that implements no-op
@@ -84,6 +95,27 @@ func (*DefaultSocketOptionsHandler) HasNIC(int32) bool {
 	return false
 }
 
+// GetSendBufferSize implements SocketOptionsHandler.GetSendBufferSize.
+func (*DefaultSocketOptionsHandler) GetSendBufferSize() (int64, *Error) {
+	return 0, nil
+}
+
+// IsUnixSocket implements SocketOptionsHandler.IsUnixSocket.
+func (*DefaultSocketOptionsHandler) IsUnixSocket() bool {
+	return false
+}
+
+// StackHandler holds methods to access the stack options. These must be
+// implemented by the stack.
+type StackHandler interface {
+	// Option allows retrieving stack wide options.
+	Option(option interface{}) *Error
+
+	// TransportProtocolOption allows retrieving individual protocol level
+	// option values.
+	TransportProtocolOption(proto TransportProtocolNumber, option GettableTransportProtocolOption) *Error
+}
+
 // SocketOptions contains all the variables which store values for SOL_SOCKET,
 // SOL_IP, SOL_IPV6 and SOL_TCP level options.
 //
@@ -91,6 +123,9 @@ func (*DefaultSocketOptionsHandler) HasNIC(int32) bool {
 type SocketOptions struct {
 	handler SocketOptionsHandler
 
+	// StackHandler is initialized at the creation time and will not change.
+	stackHandler StackHandler `state:"manual"`
+
 	// These fields are accessed and modified using atomic operations.
 
 	// broadcastEnabled determines whether datagram sockets are allowed to
@@ -170,6 +205,9 @@ type SocketOptions struct {
 	// bindToDevice determines the device to which the socket is bound.
 	bindToDevice int32
 
+	// sendBufferSize determines the send buffer size for this socket.
+	sendBufferSize int64
+
 	// mu protects the access to the below fields.
 	mu sync.Mutex `state:"nosave"`
 
@@ -180,8 +218,9 @@ type SocketOptions struct {
 
 // InitHandler initializes the handler. This must be called before using the
 // socket options utility.
-func (so *SocketOptions) InitHandler(handler SocketOptionsHandler) {
+func (so *SocketOptions) InitHandler(handler SocketOptionsHandler, stack StackHandler) {
 	so.handler = handler
+	so.stackHandler = stack
 }
 
 func storeAtomicBool(addr *uint32, v bool) {
@@ -518,3 +557,41 @@ func (so *SocketOptions) SetBindToDevice(bindToDevice int32) *Error {
 	atomic.StoreInt32(&so.bindToDevice, bindToDevice)
 	return nil
 }
+
+// GetSendBufferSize gets value for SO_SNDBUF option.
+func (so *SocketOptions) GetSendBufferSize() (int64, *Error) {
+	if so.handler.IsUnixSocket() {
+		return so.handler.GetSendBufferSize()
+	}
+	return atomic.LoadInt64(&so.sendBufferSize), nil
+}
+
+// SetSendBufferSize sets value for SO_SNDBUF option. notify indicates if the
+// stack handler should be invoked to set the send buffer size.
+func (so *SocketOptions) SetSendBufferSize(sendBufferSize int64, notify bool, getBufferLimits GetSendBufferLimits) {
+	v := sendBufferSize
+	ss := getBufferLimits(so.stackHandler)
+
+	if notify {
+		// TODO(b/176170271): Notify waiters after size has grown.
+		// Make sure the send buffer size is within the min and max
+		// allowed.
+		min := int64(ss.Min)
+		max := int64(ss.Max)
+		// Validate the send buffer size with min and max values.
+		// Multiply it by factor of 2.
+		if v > max {
+			v = max
+		}
+
+		if v < math.MaxInt32/PacketOverheadFactor {
+			v *= PacketOverheadFactor
+			if v < min {
+				v = min
+			}
+		} else {
+			v = math.MaxInt32
+		}
+	}
+	atomic.StoreInt64(&so.sendBufferSize, v)
+}
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index ee05c6013..fc7b9ea56 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -444,7 +444,7 @@ type Stack struct {
 
 	// sendBufferSize holds the min/default/max send buffer sizes for
 	// endpoints other than TCP.
-	sendBufferSize SendBufferSizeOption
+	sendBufferSize tcpip.SendBufferSizeOption
 
 	// receiveBufferSize holds the min/default/max receive buffer sizes for
 	// endpoints other than TCP.
@@ -646,7 +646,7 @@ func New(opts Options) *Stack {
 		uniqueIDGenerator:  opts.UniqueID,
 		nudDisp:            opts.NUDDisp,
 		randomGenerator:    mathrand.New(randSrc),
-		sendBufferSize: SendBufferSizeOption{
+		sendBufferSize: tcpip.SendBufferSizeOption{
 			Min:     MinBufferSize,
 			Default: DefaultBufferSize,
 			Max:     DefaultMaxBufferSize,
diff --git a/pkg/tcpip/stack/stack_options.go b/pkg/tcpip/stack/stack_options.go
index 0b093e6c5..92e70f94e 100644
--- a/pkg/tcpip/stack/stack_options.go
+++ b/pkg/tcpip/stack/stack_options.go
@@ -14,7 +14,9 @@
 
 package stack
 
-import "gvisor.dev/gvisor/pkg/tcpip"
+import (
+	"gvisor.dev/gvisor/pkg/tcpip"
+)
 
 const (
 	// MinBufferSize is the smallest size of a receive or send buffer.
@@ -29,14 +31,6 @@ const (
 	DefaultMaxBufferSize = 4 << 20 // 4 MiB
 )
 
-// SendBufferSizeOption is used by stack.(Stack*).Option/SetOption to
-// get/set the default, min and max send buffer sizes.
-type SendBufferSizeOption struct {
-	Min     int
-	Default int
-	Max     int
-}
-
 // ReceiveBufferSizeOption is used by stack.(Stack*).Option/SetOption to
 // get/set the default, min and max receive buffer sizes.
 type ReceiveBufferSizeOption struct {
@@ -48,7 +42,7 @@ type ReceiveBufferSizeOption struct {
 // SetOption allows setting stack wide options.
 func (s *Stack) SetOption(option interface{}) *tcpip.Error {
 	switch v := option.(type) {
-	case SendBufferSizeOption:
+	case tcpip.SendBufferSizeOption:
 		// Make sure we don't allow lowering the buffer below minimum
 		// required for stack to work.
 		if v.Min < MinBufferSize {
@@ -88,7 +82,7 @@ func (s *Stack) SetOption(option interface{}) *tcpip.Error {
 // Option allows retrieving stack wide options.
 func (s *Stack) Option(option interface{}) *tcpip.Error {
 	switch v := option.(type) {
-	case *SendBufferSizeOption:
+	case *tcpip.SendBufferSizeOption:
 		s.mu.RLock()
 		*v = s.sendBufferSize
 		s.mu.RUnlock()
diff --git a/pkg/tcpip/stack/stack_test.go b/pkg/tcpip/stack/stack_test.go
index b94568a8e..0f02f1d53 100644
--- a/pkg/tcpip/stack/stack_test.go
+++ b/pkg/tcpip/stack/stack_test.go
@@ -3336,21 +3336,21 @@ func TestStackSendBufferSizeOption(t *testing.T) {
 	const sMin = stack.MinBufferSize
 	testCases := []struct {
 		name string
-		ss   stack.SendBufferSizeOption
+		ss   tcpip.SendBufferSizeOption
 		err  *tcpip.Error
 	}{
 		// Invalid configurations.
-		{"min_below_zero", stack.SendBufferSizeOption{Min: -1, Default: sMin, Max: sMin}, tcpip.ErrInvalidOptionValue},
-		{"min_zero", stack.SendBufferSizeOption{Min: 0, Default: sMin, Max: sMin}, tcpip.ErrInvalidOptionValue},
-		{"default_below_min", stack.SendBufferSizeOption{Min: 0, Default: sMin - 1, Max: sMin - 1}, tcpip.ErrInvalidOptionValue},
-		{"default_above_max", stack.SendBufferSizeOption{Min: 0, Default: sMin + 1, Max: sMin}, tcpip.ErrInvalidOptionValue},
-		{"max_below_min", stack.SendBufferSizeOption{Min: sMin, Default: sMin + 1, Max: sMin - 1}, tcpip.ErrInvalidOptionValue},
+		{"min_below_zero", tcpip.SendBufferSizeOption{Min: -1, Default: sMin, Max: sMin}, tcpip.ErrInvalidOptionValue},
+		{"min_zero", tcpip.SendBufferSizeOption{Min: 0, Default: sMin, Max: sMin}, tcpip.ErrInvalidOptionValue},
+		{"default_below_min", tcpip.SendBufferSizeOption{Min: 0, Default: sMin - 1, Max: sMin - 1}, tcpip.ErrInvalidOptionValue},
+		{"default_above_max", tcpip.SendBufferSizeOption{Min: 0, Default: sMin + 1, Max: sMin}, tcpip.ErrInvalidOptionValue},
+		{"max_below_min", tcpip.SendBufferSizeOption{Min: sMin, Default: sMin + 1, Max: sMin - 1}, tcpip.ErrInvalidOptionValue},
 
 		// Valid Configurations
-		{"in_ascending_order", stack.SendBufferSizeOption{Min: sMin, Default: sMin + 1, Max: sMin + 2}, nil},
-		{"all_equal", stack.SendBufferSizeOption{Min: sMin, Default: sMin, Max: sMin}, nil},
-		{"min_default_equal", stack.SendBufferSizeOption{Min: sMin, Default: sMin, Max: sMin + 1}, nil},
-		{"default_max_equal", stack.SendBufferSizeOption{Min: sMin, Default: sMin + 1, Max: sMin + 1}, nil},
+		{"in_ascending_order", tcpip.SendBufferSizeOption{Min: sMin, Default: sMin + 1, Max: sMin + 2}, nil},
+		{"all_equal", tcpip.SendBufferSizeOption{Min: sMin, Default: sMin, Max: sMin}, nil},
+		{"min_default_equal", tcpip.SendBufferSizeOption{Min: sMin, Default: sMin, Max: sMin + 1}, nil},
+		{"default_max_equal", tcpip.SendBufferSizeOption{Min: sMin, Default: sMin + 1, Max: sMin + 1}, nil},
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
@@ -3359,7 +3359,7 @@ func TestStackSendBufferSizeOption(t *testing.T) {
 			if err := s.SetOption(tc.ss); err != tc.err {
 				t.Fatalf("s.SetOption(%+v) = %v, want: %v", tc.ss, err, tc.err)
 			}
-			var ss stack.SendBufferSizeOption
+			var ss tcpip.SendBufferSizeOption
 			if tc.err == nil {
 				if err := s.Option(&ss); err != nil {
 					t.Fatalf("s.Option(%+v) = %v, want: nil", ss, err)
diff --git a/pkg/tcpip/stack/transport_test.go b/pkg/tcpip/stack/transport_test.go
index dbf8b4db1..f1ac8b777 100644
--- a/pkg/tcpip/stack/transport_test.go
+++ b/pkg/tcpip/stack/transport_test.go
@@ -68,9 +68,9 @@ func (f *fakeTransportEndpoint) SocketOptions() *tcpip.SocketOptions {
 	return &f.ops
 }
 
-func newFakeTransportEndpoint(proto *fakeTransportProtocol, netProto tcpip.NetworkProtocolNumber, uniqueID uint64) tcpip.Endpoint {
-	ep := &fakeTransportEndpoint{TransportEndpointInfo: stack.TransportEndpointInfo{NetProto: netProto}, proto: proto, uniqueID: uniqueID}
-	ep.ops.InitHandler(ep)
+func newFakeTransportEndpoint(proto *fakeTransportProtocol, netProto tcpip.NetworkProtocolNumber, s *stack.Stack) tcpip.Endpoint {
+	ep := &fakeTransportEndpoint{TransportEndpointInfo: stack.TransportEndpointInfo{NetProto: netProto}, proto: proto, uniqueID: s.UniqueID()}
+	ep.ops.InitHandler(ep, s)
 	return ep
 }
 
@@ -234,7 +234,7 @@ func (f *fakeTransportEndpoint) HandlePacket(id stack.TransportEndpointID, pkt *
 		peerAddr: route.RemoteAddress,
 		route:    route,
 	}
-	ep.ops.InitHandler(ep)
+	ep.ops.InitHandler(ep, f.proto.stack)
 	f.acceptQueue = append(f.acceptQueue, ep)
 }
 
@@ -282,7 +282,7 @@ func (*fakeTransportProtocol) Number() tcpip.TransportProtocolNumber {
 }
 
 func (f *fakeTransportProtocol) NewEndpoint(netProto tcpip.NetworkProtocolNumber, _ *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
-	return newFakeTransportEndpoint(f, netProto, f.stack.UniqueID()), nil
+	return newFakeTransportEndpoint(f, netProto, f.stack), nil
 }
 
 func (*fakeTransportProtocol) NewRawEndpoint(tcpip.NetworkProtocolNumber, *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 32e4f02ca..4e2c4f906 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -826,10 +826,6 @@ const (
 	// number of unread bytes in the input buffer should be returned.
 	ReceiveQueueSizeOption
 
-	// SendBufferSizeOption is used by SetSockOptInt/GetSockOptInt to
-	// specify the send buffer size option.
-	SendBufferSizeOption
-
 	// ReceiveBufferSizeOption is used by SetSockOptInt/GetSockOptInt to
 	// specify the receive buffer size option.
 	ReceiveBufferSizeOption
@@ -1234,6 +1230,31 @@ type IPPacketInfo struct {
 	DestinationAddr Address
 }
 
+// SendBufferSizeOption is used by stack.(Stack*).Option/SetOption to
+// get/set the default, min and max send buffer sizes.
+type SendBufferSizeOption struct {
+	// Min is the minimum size for send buffer.
+	Min int
+
+	// Default is the default size for send buffer.
+	Default int
+
+	// Max is the maximum size for send buffer.
+	Max int
+}
+
+// GetSendBufferLimits is used to get the send buffer size limits.
+type GetSendBufferLimits func(StackHandler) SendBufferSizeOption
+
+// GetStackSendBufferLimits is used to get default, min and max send buffer size.
+func GetStackSendBufferLimits(so StackHandler) SendBufferSizeOption {
+	var ss SendBufferSizeOption
+	if err := so.Option(&ss); err != nil {
+		panic(fmt.Sprintf("s.Option(%#v) = %s", ss, err))
+	}
+	return ss
+}
+
 // Route is a row in the routing table. It specifies through which NIC (and
 // gateway) sets of packets should be routed. A row is considered viable if the
 // masked target address matches the destination address in the row.
diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index af00ed548..85b497365 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -69,8 +69,7 @@ type endpoint struct {
 	rcvClosed     bool
 
 	// The following fields are protected by the mu mutex.
-	mu         sync.RWMutex `state:"nosave"`
-	sndBufSize int
+	mu sync.RWMutex `state:"nosave"`
 	// shutdownFlags represent the current shutdown state of the endpoint.
 	shutdownFlags tcpip.ShutdownFlags
 	state         endpointState
@@ -94,11 +93,17 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, transProt
 		},
 		waiterQueue:   waiterQueue,
 		rcvBufSizeMax: 32 * 1024,
-		sndBufSize:    32 * 1024,
 		state:         stateInitial,
 		uniqueID:      s.UniqueID(),
 	}
-	ep.ops.InitHandler(ep)
+	ep.ops.InitHandler(ep, ep.stack)
+	ep.ops.SetSendBufferSize(32*1024, false /* notify */, tcpip.GetStackSendBufferLimits)
+
+	// Override with stack defaults.
+	var ss tcpip.SendBufferSizeOption
+	if err := s.Option(&ss); err == nil {
+		ep.ops.SetSendBufferSize(int64(ss.Default), false /* notify */, tcpip.GetStackSendBufferLimits)
+	}
 	return ep, nil
 }
 
@@ -363,11 +368,6 @@ func (e *endpoint) GetSockOptInt(opt tcpip.SockOptInt) (int, *tcpip.Error) {
 		}
 		e.rcvMu.Unlock()
 		return v, nil
-	case tcpip.SendBufferSizeOption:
-		e.mu.Lock()
-		v := e.sndBufSize
-		e.mu.Unlock()
-		return v, nil
 
 	case tcpip.ReceiveBufferSizeOption:
 		e.rcvMu.Lock()
diff --git a/pkg/tcpip/transport/icmp/endpoint_state.go b/pkg/tcpip/transport/icmp/endpoint_state.go
index 9d263c0ec..9335cbc5a 100644
--- a/pkg/tcpip/transport/icmp/endpoint_state.go
+++ b/pkg/tcpip/transport/icmp/endpoint_state.go
@@ -69,6 +69,7 @@ func (e *endpoint) afterLoad() {
 // Resume implements tcpip.ResumableEndpoint.Resume.
 func (e *endpoint) Resume(s *stack.Stack) {
 	e.stack = s
+	e.ops.InitHandler(e, e.stack)
 
 	if e.state != stateBound && e.state != stateConnected {
 		return
diff --git a/pkg/tcpip/transport/packet/endpoint.go b/pkg/tcpip/transport/packet/endpoint.go
index 6fd116a98..9ca9c9780 100644
--- a/pkg/tcpip/transport/packet/endpoint.go
+++ b/pkg/tcpip/transport/packet/endpoint.go
@@ -79,13 +79,11 @@ type endpoint struct {
 	rcvClosed     bool
 
 	// The following fields are protected by mu.
-	mu            sync.RWMutex `state:"nosave"`
-	sndBufSize    int
-	sndBufSizeMax int
-	closed        bool
-	stats         tcpip.TransportEndpointStats `state:"nosave"`
-	bound         bool
-	boundNIC      tcpip.NICID
+	mu       sync.RWMutex `state:"nosave"`
+	closed   bool
+	stats    tcpip.TransportEndpointStats `state:"nosave"`
+	bound    bool
+	boundNIC tcpip.NICID
 
 	// lastErrorMu protects lastError.
 	lastErrorMu sync.Mutex   `state:"nosave"`
@@ -106,14 +104,13 @@ func NewEndpoint(s *stack.Stack, cooked bool, netProto tcpip.NetworkProtocolNumb
 		netProto:      netProto,
 		waiterQueue:   waiterQueue,
 		rcvBufSizeMax: 32 * 1024,
-		sndBufSize:    32 * 1024,
 	}
-	ep.ops.InitHandler(ep)
+	ep.ops.InitHandler(ep, ep.stack)
 
 	// Override with stack defaults.
-	var ss stack.SendBufferSizeOption
+	var ss tcpip.SendBufferSizeOption
 	if err := s.Option(&ss); err == nil {
-		ep.sndBufSizeMax = ss.Default
+		ep.ops.SetSendBufferSize(int64(ss.Default), false /* notify */, tcpip.GetStackSendBufferLimits)
 	}
 
 	var rs stack.ReceiveBufferSizeOption
@@ -320,24 +317,6 @@ func (ep *endpoint) SetSockOpt(opt tcpip.SettableSocketOption) *tcpip.Error {
 // SetSockOptInt implements tcpip.Endpoint.SetSockOptInt.
 func (ep *endpoint) SetSockOptInt(opt tcpip.SockOptInt, v int) *tcpip.Error {
 	switch opt {
-	case tcpip.SendBufferSizeOption:
-		// Make sure the send buffer size is within the min and max
-		// allowed.
-		var ss stack.SendBufferSizeOption
-		if err := ep.stack.Option(&ss); err != nil {
-			panic(fmt.Sprintf("s.Option(%#v) = %s", ss, err))
-		}
-		if v > ss.Max {
-			v = ss.Max
-		}
-		if v < ss.Min {
-			v = ss.Min
-		}
-		ep.mu.Lock()
-		ep.sndBufSizeMax = v
-		ep.mu.Unlock()
-		return nil
-
 	case tcpip.ReceiveBufferSizeOption:
 		// Make sure the receive buffer size is within the min and max
 		// allowed.
@@ -395,12 +374,6 @@ func (ep *endpoint) GetSockOptInt(opt tcpip.SockOptInt) (int, *tcpip.Error) {
 		ep.rcvMu.Unlock()
 		return v, nil
 
-	case tcpip.SendBufferSizeOption:
-		ep.mu.Lock()
-		v := ep.sndBufSizeMax
-		ep.mu.Unlock()
-		return v, nil
-
 	case tcpip.ReceiveBufferSizeOption:
 		ep.rcvMu.Lock()
 		v := ep.rcvBufSizeMax
diff --git a/pkg/tcpip/transport/packet/endpoint_state.go b/pkg/tcpip/transport/packet/endpoint_state.go
index e2fa96d17..61221be71 100644
--- a/pkg/tcpip/transport/packet/endpoint_state.go
+++ b/pkg/tcpip/transport/packet/endpoint_state.go
@@ -63,8 +63,8 @@ func (ep *endpoint) loadRcvBufSizeMax(max int) {
 
 // afterLoad is invoked by stateify.
 func (ep *endpoint) afterLoad() {
-	// StackFromEnv is a stack used specifically for save/restore.
 	ep.stack = stack.StackFromEnv
+	ep.ops.InitHandler(ep, ep.stack)
 
 	// TODO(gvisor.dev/173): Once bind is supported, choose the right NIC.
 	if err := ep.stack.RegisterPacketEndpoint(0, ep.netProto, ep); err != nil {
diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go
index 2dacf5a64..f038097e4 100644
--- a/pkg/tcpip/transport/raw/endpoint.go
+++ b/pkg/tcpip/transport/raw/endpoint.go
@@ -76,12 +76,10 @@ type endpoint struct {
 	rcvClosed     bool
 
 	// The following fields are protected by mu.
-	mu            sync.RWMutex `state:"nosave"`
-	sndBufSize    int
-	sndBufSizeMax int
-	closed        bool
-	connected     bool
-	bound         bool
+	mu        sync.RWMutex `state:"nosave"`
+	closed    bool
+	connected bool
+	bound     bool
 	// route is the route to a remote network endpoint. It is set via
 	// Connect(), and is valid only when conneted is true.
 	route *stack.Route                 `state:"manual"`
@@ -112,16 +110,16 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, transProt
 		},
 		waiterQueue:   waiterQueue,
 		rcvBufSizeMax: 32 * 1024,
-		sndBufSizeMax: 32 * 1024,
 		associated:    associated,
 	}
-	e.ops.InitHandler(e)
+	e.ops.InitHandler(e, e.stack)
 	e.ops.SetHeaderIncluded(!associated)
+	e.ops.SetSendBufferSize(32*1024, false /* notify */, tcpip.GetStackSendBufferLimits)
 
 	// Override with stack defaults.
-	var ss stack.SendBufferSizeOption
+	var ss tcpip.SendBufferSizeOption
 	if err := s.Option(&ss); err == nil {
-		e.sndBufSizeMax = ss.Default
+		e.ops.SetSendBufferSize(int64(ss.Default), false /* notify */, tcpip.GetStackSendBufferLimits)
 	}
 
 	var rs stack.ReceiveBufferSizeOption
@@ -511,24 +509,6 @@ func (e *endpoint) SetSockOpt(opt tcpip.SettableSocketOption) *tcpip.Error {
 // SetSockOptInt implements tcpip.Endpoint.SetSockOptInt.
 func (e *endpoint) SetSockOptInt(opt tcpip.SockOptInt, v int) *tcpip.Error {
 	switch opt {
-	case tcpip.SendBufferSizeOption:
-		// Make sure the send buffer size is within the min and max
-		// allowed.
-		var ss stack.SendBufferSizeOption
-		if err := e.stack.Option(&ss); err != nil {
-			panic(fmt.Sprintf("s.Option(%#v) = %s", ss, err))
-		}
-		if v > ss.Max {
-			v = ss.Max
-		}
-		if v < ss.Min {
-			v = ss.Min
-		}
-		e.mu.Lock()
-		e.sndBufSizeMax = v
-		e.mu.Unlock()
-		return nil
-
 	case tcpip.ReceiveBufferSizeOption:
 		// Make sure the receive buffer size is within the min and max
 		// allowed.
@@ -570,12 +550,6 @@ func (e *endpoint) GetSockOptInt(opt tcpip.SockOptInt) (int, *tcpip.Error) {
 		e.rcvMu.Unlock()
 		return v, nil
 
-	case tcpip.SendBufferSizeOption:
-		e.mu.Lock()
-		v := e.sndBufSizeMax
-		e.mu.Unlock()
-		return v, nil
-
 	case tcpip.ReceiveBufferSizeOption:
 		e.rcvMu.Lock()
 		v := e.rcvBufSizeMax
diff --git a/pkg/tcpip/transport/raw/endpoint_state.go b/pkg/tcpip/transport/raw/endpoint_state.go
index 4a7e1c039..e11ab38d5 100644
--- a/pkg/tcpip/transport/raw/endpoint_state.go
+++ b/pkg/tcpip/transport/raw/endpoint_state.go
@@ -69,6 +69,7 @@ func (e *endpoint) afterLoad() {
 // Resume implements tcpip.ResumableEndpoint.Resume.
 func (e *endpoint) Resume(s *stack.Stack) {
 	e.stack = s
+	e.ops.InitHandler(e, e.stack)
 
 	// If the endpoint is connected, re-connect.
 	if e.connected {
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 05c431e83..8e43fec81 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -557,7 +557,6 @@ type endpoint struct {
 	// When the send side is closed, the protocol goroutine is notified via
 	// sndCloseWaker, and sndClosed is set to true.
 	sndBufMu      sync.Mutex `state:"nosave"`
-	sndBufSize    int
 	sndBufUsed    int
 	sndClosed     bool
 	sndBufInQueue seqnum.Size
@@ -869,7 +868,6 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQue
 		waiterQueue: waiterQueue,
 		state:       StateInitial,
 		rcvBufSize:  DefaultReceiveBufferSize,
-		sndBufSize:  DefaultSendBufferSize,
 		sndMTU:      int(math.MaxInt32),
 		keepalive: keepalive{
 			// Linux defaults.
@@ -882,13 +880,14 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQue
 		windowClamp:   DefaultReceiveBufferSize,
 		maxSynRetries: DefaultSynRetries,
 	}
-	e.ops.InitHandler(e)
+	e.ops.InitHandler(e, e.stack)
 	e.ops.SetMulticastLoop(true)
 	e.ops.SetQuickAck(true)
+	e.ops.SetSendBufferSize(DefaultSendBufferSize, false /* notify */, GetTCPSendBufferLimits)
 
 	var ss tcpip.TCPSendBufferSizeRangeOption
 	if err := s.TransportProtocolOption(ProtocolNumber, &ss); err == nil {
-		e.sndBufSize = ss.Default
+		e.ops.SetSendBufferSize(int64(ss.Default), false /* notify */, GetTCPSendBufferLimits)
 	}
 
 	var rs tcpip.TCPReceiveBufferSizeRangeOption
@@ -967,7 +966,8 @@ func (e *endpoint) Readiness(mask waiter.EventMask) waiter.EventMask {
 		// Determine if the endpoint is writable if requested.
 		if (mask & waiter.EventOut) != 0 {
 			e.sndBufMu.Lock()
-			if e.sndClosed || e.sndBufUsed < e.sndBufSize {
+			sndBufSize := e.getSendBufferSize()
+			if e.sndClosed || e.sndBufUsed < sndBufSize {
 				result |= waiter.EventOut
 			}
 			e.sndBufMu.Unlock()
@@ -1499,7 +1499,8 @@ func (e *endpoint) isEndpointWritableLocked() (int, *tcpip.Error) {
 		return 0, tcpip.ErrClosedForSend
 	}
 
-	avail := e.sndBufSize - e.sndBufUsed
+	sndBufSize := e.getSendBufferSize()
+	avail := sndBufSize - e.sndBufUsed
 	if avail <= 0 {
 		return 0, tcpip.ErrWouldBlock
 	}
@@ -1692,6 +1693,14 @@ func (e *endpoint) OnCorkOptionSet(v bool) {
 	}
 }
 
+func (e *endpoint) getSendBufferSize() int {
+	sndBufSize, err := e.ops.GetSendBufferSize()
+	if err != nil {
+		panic(fmt.Sprintf("e.ops.GetSendBufferSize() = %s", err))
+	}
+	return int(sndBufSize)
+}
+
 // SetSockOptInt sets a socket option.
 func (e *endpoint) SetSockOptInt(opt tcpip.SockOptInt, v int) *tcpip.Error {
 	// Lower 2 bits represents ECN bits. RFC 3168, section 23.1
@@ -1785,31 +1794,6 @@ func (e *endpoint) SetSockOptInt(opt tcpip.SockOptInt, v int) *tcpip.Error {
 		e.rcvListMu.Unlock()
 		e.UnlockUser()
 
-	case tcpip.SendBufferSizeOption:
-		// Make sure the send buffer size is within the min and max
-		// allowed.
-		var ss tcpip.TCPSendBufferSizeRangeOption
-		if err := e.stack.TransportProtocolOption(ProtocolNumber, &ss); err != nil {
-			panic(fmt.Sprintf("e.stack.TransportProtocolOption(%d, %#v) = %s", ProtocolNumber, &ss, err))
-		}
-
-		if v > ss.Max {
-			v = ss.Max
-		}
-
-		if v < math.MaxInt32/SegOverheadFactor {
-			v *= SegOverheadFactor
-			if v < ss.Min {
-				v = ss.Min
-			}
-		} else {
-			v = math.MaxInt32
-		}
-
-		e.sndBufMu.Lock()
-		e.sndBufSize = v
-		e.sndBufMu.Unlock()
-
 	case tcpip.TTLOption:
 		e.LockUser()
 		e.ttl = uint8(v)
@@ -1995,12 +1979,6 @@ func (e *endpoint) GetSockOptInt(opt tcpip.SockOptInt) (int, *tcpip.Error) {
 	case tcpip.ReceiveQueueSizeOption:
 		return e.readyReceiveSize()
 
-	case tcpip.SendBufferSizeOption:
-		e.sndBufMu.Lock()
-		v := e.sndBufSize
-		e.sndBufMu.Unlock()
-		return v, nil
-
 	case tcpip.ReceiveBufferSizeOption:
 		e.rcvListMu.Lock()
 		v := e.rcvBufSize
@@ -2749,13 +2727,14 @@ func (e *endpoint) HandleControlPacket(typ stack.ControlType, extra uint32, pkt
 // updateSndBufferUsage is called by the protocol goroutine when room opens up
 // in the send buffer. The number of newly available bytes is v.
 func (e *endpoint) updateSndBufferUsage(v int) {
+	sendBufferSize := e.getSendBufferSize()
 	e.sndBufMu.Lock()
-	notify := e.sndBufUsed >= e.sndBufSize>>1
+	notify := e.sndBufUsed >= sendBufferSize>>1
 	e.sndBufUsed -= v
-	// We only notify when there is half the sndBufSize available after
+	// We only notify when there is half the sendBufferSize available after
 	// a full buffer event occurs. This ensures that we don't wake up
 	// writers to queue just 1-2 segments and go back to sleep.
-	notify = notify && e.sndBufUsed < e.sndBufSize>>1
+	notify = notify && e.sndBufUsed < int(sendBufferSize)>>1
 	e.sndBufMu.Unlock()
 
 	if notify {
@@ -2967,8 +2946,9 @@ func (e *endpoint) completeState() stack.TCPEndpointState {
 	s.SACK.ReceivedBlocks, s.SACK.MaxSACKED = e.scoreboard.Copy()
 
 	// Copy endpoint send state.
+	sndBufSize := e.getSendBufferSize()
 	e.sndBufMu.Lock()
-	s.SndBufSize = e.sndBufSize
+	s.SndBufSize = sndBufSize
 	s.SndBufUsed = e.sndBufUsed
 	s.SndClosed = e.sndClosed
 	s.SndBufInQueue = e.sndBufInQueue
@@ -3113,3 +3093,17 @@ func (e *endpoint) Wait() {
 func (e *endpoint) SocketOptions() *tcpip.SocketOptions {
 	return &e.ops
 }
+
+// GetTCPSendBufferLimits is used to get send buffer size limits for TCP.
+func GetTCPSendBufferLimits(s tcpip.StackHandler) tcpip.SendBufferSizeOption {
+	var ss tcpip.TCPSendBufferSizeRangeOption
+	if err := s.TransportProtocolOption(header.TCPProtocolNumber, &ss); err != nil {
+		panic(fmt.Sprintf("s.TransportProtocolOption(%d, %#v) = %s", header.TCPProtocolNumber, ss, err))
+	}
+
+	return tcpip.SendBufferSizeOption{
+		Min:     ss.Min,
+		Default: ss.Default,
+		Max:     ss.Max,
+	}
+}
diff --git a/pkg/tcpip/transport/tcp/endpoint_state.go b/pkg/tcpip/transport/tcp/endpoint_state.go
index ba67176b5..19c1dc67a 100644
--- a/pkg/tcpip/transport/tcp/endpoint_state.go
+++ b/pkg/tcpip/transport/tcp/endpoint_state.go
@@ -179,14 +179,16 @@ func (e *endpoint) afterLoad() {
 // Resume implements tcpip.ResumableEndpoint.Resume.
 func (e *endpoint) Resume(s *stack.Stack) {
 	e.stack = s
+	e.ops.InitHandler(e, e.stack)
 	e.segmentQueue.thaw()
 	epState := e.origEndpointState
 	switch epState {
 	case StateInitial, StateBound, StateListen, StateConnecting, StateEstablished:
 		var ss tcpip.TCPSendBufferSizeRangeOption
 		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))
+			sendBufferSize := e.getSendBufferSize()
+			if sendBufferSize < ss.Min || sendBufferSize > ss.Max {
+				panic(fmt.Sprintf("endpoint sendBufferSize %d is outside the min and max allowed [%d, %d]", sendBufferSize, ss.Min, ss.Max))
 			}
 		}
 
diff --git a/pkg/tcpip/transport/tcp/tcp_test.go b/pkg/tcpip/transport/tcp/tcp_test.go
index db9dc4e25..754f6b92a 100644
--- a/pkg/tcpip/transport/tcp/tcp_test.go
+++ b/pkg/tcpip/transport/tcp/tcp_test.go
@@ -4365,9 +4365,9 @@ func checkRecvBufferSize(t *testing.T, ep tcpip.Endpoint, v int) {
 func checkSendBufferSize(t *testing.T, ep tcpip.Endpoint, v int) {
 	t.Helper()
 
-	s, err := ep.GetSockOptInt(tcpip.SendBufferSizeOption)
+	s, err := ep.SocketOptions().GetSendBufferSize()
 	if err != nil {
-		t.Fatalf("GetSockOpt failed: %s", err)
+		t.Fatalf("GetSendBufferSize failed: %s", err)
 	}
 
 	if int(s) != v {
@@ -4473,9 +4473,7 @@ func TestMinMaxBufferSizes(t *testing.T) {
 
 	checkRecvBufferSize(t, ep, 200)
 
-	if err := ep.SetSockOptInt(tcpip.SendBufferSizeOption, 149); err != nil {
-		t.Fatalf("SetSockOptInt(SendBufferSizeOption, 299) failed: %s", err)
-	}
+	ep.SocketOptions().SetSendBufferSize(149, true, tcp.GetTCPSendBufferLimits)
 
 	checkSendBufferSize(t, ep, 300)
 
@@ -4487,9 +4485,7 @@ func TestMinMaxBufferSizes(t *testing.T) {
 	// Values above max are capped at max and then doubled.
 	checkRecvBufferSize(t, ep, tcp.DefaultReceiveBufferSize*20*2)
 
-	if err := ep.SetSockOptInt(tcpip.SendBufferSizeOption, 1+tcp.DefaultSendBufferSize*30); err != nil {
-		t.Fatalf("SetSockOptInt(SendBufferSizeOption) failed: %s", err)
-	}
+	ep.SocketOptions().SetSendBufferSize(1+tcp.DefaultSendBufferSize*30, true, tcp.GetTCPSendBufferLimits)
 
 	// Values above max are capped at max and then doubled.
 	checkSendBufferSize(t, ep, tcp.DefaultSendBufferSize*30*2)
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 8544fcb08..ee7e43b97 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -97,9 +97,7 @@ type endpoint struct {
 	rcvClosed     bool
 
 	// The following fields are protected by the mu mutex.
-	mu            sync.RWMutex `state:"nosave"`
-	sndBufSize    int
-	sndBufSizeMax int
+	mu sync.RWMutex `state:"nosave"`
 	// state must be read/set using the EndpointState()/setEndpointState()
 	// methods.
 	state          EndpointState
@@ -176,18 +174,18 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQue
 		// Linux defaults to TTL=1.
 		multicastTTL:         1,
 		rcvBufSizeMax:        32 * 1024,
-		sndBufSizeMax:        32 * 1024,
 		multicastMemberships: make(map[multicastMembership]struct{}),
 		state:                StateInitial,
 		uniqueID:             s.UniqueID(),
 	}
-	e.ops.InitHandler(e)
+	e.ops.InitHandler(e, e.stack)
 	e.ops.SetMulticastLoop(true)
+	e.ops.SetSendBufferSize(32*1024, false /* notify */, tcpip.GetStackSendBufferLimits)
 
 	// Override with stack defaults.
-	var ss stack.SendBufferSizeOption
+	var ss tcpip.SendBufferSizeOption
 	if err := s.Option(&ss); err == nil {
-		e.sndBufSizeMax = ss.Default
+		e.ops.SetSendBufferSize(int64(ss.Default), false /* notify */, tcpip.GetStackSendBufferLimits)
 	}
 
 	var rs stack.ReceiveBufferSizeOption
@@ -632,25 +630,6 @@ func (e *endpoint) SetSockOptInt(opt tcpip.SockOptInt, v int) *tcpip.Error {
 		e.rcvBufSizeMax = v
 		e.mu.Unlock()
 		return nil
-	case tcpip.SendBufferSizeOption:
-		// Make sure the send buffer size is within the min and max
-		// allowed.
-		var ss stack.SendBufferSizeOption
-		if err := e.stack.Option(&ss); err != nil {
-			panic(fmt.Sprintf("e.stack.Option(%#v) = %s", ss, err))
-		}
-
-		if v < ss.Min {
-			v = ss.Min
-		}
-		if v > ss.Max {
-			v = ss.Max
-		}
-
-		e.mu.Lock()
-		e.sndBufSizeMax = v
-		e.mu.Unlock()
-		return nil
 	}
 
 	return nil
@@ -811,12 +790,6 @@ func (e *endpoint) GetSockOptInt(opt tcpip.SockOptInt) (int, *tcpip.Error) {
 		e.rcvMu.Unlock()
 		return v, nil
 
-	case tcpip.SendBufferSizeOption:
-		e.mu.Lock()
-		v := e.sndBufSizeMax
-		e.mu.Unlock()
-		return v, nil
-
 	case tcpip.ReceiveBufferSizeOption:
 		e.rcvMu.Lock()
 		v := e.rcvBufSizeMax
diff --git a/pkg/tcpip/transport/udp/endpoint_state.go b/pkg/tcpip/transport/udp/endpoint_state.go
index 13b72dc88..903397f1c 100644
--- a/pkg/tcpip/transport/udp/endpoint_state.go
+++ b/pkg/tcpip/transport/udp/endpoint_state.go
@@ -91,6 +91,7 @@ func (e *endpoint) Resume(s *stack.Stack) {
 	defer e.mu.Unlock()
 
 	e.stack = s
+	e.ops.InitHandler(e, e.stack)
 
 	for m := range e.multicastMemberships {
 		if err := e.stack.JoinGroup(e.NetProto, m.nicID, m.multicastAddr); err != nil {