From d35f07b36a40ee94b3a5b588a5fa62572753c620 Mon Sep 17 00:00:00 2001
From: Ghanan Gowripalan <ghanan@google.com>
Date: Tue, 8 Sep 2020 12:15:58 -0700
Subject: Improve type safety for transport protocol options

The existing implementation for TransportProtocol.{Set}Option take
arguments of an empty interface type which all types (implicitly)
implement; any type may be passed to the functions.

This change introduces marker interfaces for transport protocol options
that may be set or queried which transport protocol option types
implement to ensure that invalid types are caught at compile time.
Different interfaces are used to allow the compiler to enforce read-only
or set-only socket options.

RELNOTES: n/a
PiperOrigin-RevId: 330559811
---
 pkg/sentry/socket/netstack/stack.go | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

(limited to 'pkg/sentry/socket')

diff --git a/pkg/sentry/socket/netstack/stack.go b/pkg/sentry/socket/netstack/stack.go
index f0fe18684..36144e1eb 100644
--- a/pkg/sentry/socket/netstack/stack.go
+++ b/pkg/sentry/socket/netstack/stack.go
@@ -155,7 +155,7 @@ func (s *Stack) AddInterfaceAddr(idx int32, addr inet.InterfaceAddr) error {
 
 // TCPReceiveBufferSize implements inet.Stack.TCPReceiveBufferSize.
 func (s *Stack) TCPReceiveBufferSize() (inet.TCPBufferSize, error) {
-	var rs tcp.ReceiveBufferSizeOption
+	var rs tcpip.TCPReceiveBufferSizeRangeOption
 	err := s.Stack.TransportProtocolOption(tcp.ProtocolNumber, &rs)
 	return inet.TCPBufferSize{
 		Min:     rs.Min,
@@ -166,17 +166,17 @@ func (s *Stack) TCPReceiveBufferSize() (inet.TCPBufferSize, error) {
 
 // SetTCPReceiveBufferSize implements inet.Stack.SetTCPReceiveBufferSize.
 func (s *Stack) SetTCPReceiveBufferSize(size inet.TCPBufferSize) error {
-	rs := tcp.ReceiveBufferSizeOption{
+	rs := tcpip.TCPReceiveBufferSizeRangeOption{
 		Min:     size.Min,
 		Default: size.Default,
 		Max:     size.Max,
 	}
-	return syserr.TranslateNetstackError(s.Stack.SetTransportProtocolOption(tcp.ProtocolNumber, rs)).ToError()
+	return syserr.TranslateNetstackError(s.Stack.SetTransportProtocolOption(tcp.ProtocolNumber, &rs)).ToError()
 }
 
 // TCPSendBufferSize implements inet.Stack.TCPSendBufferSize.
 func (s *Stack) TCPSendBufferSize() (inet.TCPBufferSize, error) {
-	var ss tcp.SendBufferSizeOption
+	var ss tcpip.TCPSendBufferSizeRangeOption
 	err := s.Stack.TransportProtocolOption(tcp.ProtocolNumber, &ss)
 	return inet.TCPBufferSize{
 		Min:     ss.Min,
@@ -187,29 +187,30 @@ func (s *Stack) TCPSendBufferSize() (inet.TCPBufferSize, error) {
 
 // SetTCPSendBufferSize implements inet.Stack.SetTCPSendBufferSize.
 func (s *Stack) SetTCPSendBufferSize(size inet.TCPBufferSize) error {
-	ss := tcp.SendBufferSizeOption{
+	ss := tcpip.TCPSendBufferSizeRangeOption{
 		Min:     size.Min,
 		Default: size.Default,
 		Max:     size.Max,
 	}
-	return syserr.TranslateNetstackError(s.Stack.SetTransportProtocolOption(tcp.ProtocolNumber, ss)).ToError()
+	return syserr.TranslateNetstackError(s.Stack.SetTransportProtocolOption(tcp.ProtocolNumber, &ss)).ToError()
 }
 
 // TCPSACKEnabled implements inet.Stack.TCPSACKEnabled.
 func (s *Stack) TCPSACKEnabled() (bool, error) {
-	var sack tcp.SACKEnabled
+	var sack tcpip.TCPSACKEnabled
 	err := s.Stack.TransportProtocolOption(tcp.ProtocolNumber, &sack)
 	return bool(sack), syserr.TranslateNetstackError(err).ToError()
 }
 
 // SetTCPSACKEnabled implements inet.Stack.SetTCPSACKEnabled.
 func (s *Stack) SetTCPSACKEnabled(enabled bool) error {
-	return syserr.TranslateNetstackError(s.Stack.SetTransportProtocolOption(tcp.ProtocolNumber, tcp.SACKEnabled(enabled))).ToError()
+	opt := tcpip.TCPSACKEnabled(enabled)
+	return syserr.TranslateNetstackError(s.Stack.SetTransportProtocolOption(tcp.ProtocolNumber, &opt)).ToError()
 }
 
 // TCPRecovery implements inet.Stack.TCPRecovery.
 func (s *Stack) TCPRecovery() (inet.TCPLossRecovery, error) {
-	var recovery tcp.Recovery
+	var recovery tcpip.TCPRecovery
 	if err := s.Stack.TransportProtocolOption(tcp.ProtocolNumber, &recovery); err != nil {
 		return 0, syserr.TranslateNetstackError(err).ToError()
 	}
@@ -218,7 +219,8 @@ func (s *Stack) TCPRecovery() (inet.TCPLossRecovery, error) {
 
 // SetTCPRecovery implements inet.Stack.SetTCPRecovery.
 func (s *Stack) SetTCPRecovery(recovery inet.TCPLossRecovery) error {
-	return syserr.TranslateNetstackError(s.Stack.SetTransportProtocolOption(tcp.ProtocolNumber, tcp.Recovery(recovery))).ToError()
+	opt := tcpip.TCPRecovery(recovery)
+	return syserr.TranslateNetstackError(s.Stack.SetTransportProtocolOption(tcp.ProtocolNumber, &opt)).ToError()
 }
 
 // Statistics implements inet.Stack.Statistics.
-- 
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