Add loss recovery option for TCP.

/proc/sys/net/ipv4/tcp_recovery is used to enable RACK loss
recovery in TCP.

PiperOrigin-RevId: 325157807

2 files changed, 25 insertions, 0 deletions

diff --git a/pkg/sentry/socket/hostinet/stack.go b/pkg/sentry/socket/hostinet/stack.go
index a48082631..fda3dcb35 100644
--- a/pkg/sentry/socket/hostinet/stack.go
+++ b/pkg/sentry/socket/hostinet/stack.go
@@ -53,6 +53,7 @@ type Stack struct {
 	interfaceAddrs map[int32][]inet.InterfaceAddr
 	routes         []inet.Route
 	supportsIPv6   bool
+	tcpRecovery    inet.TCPLossRecovery
 	tcpRecvBufSize inet.TCPBufferSize
 	tcpSendBufSize inet.TCPBufferSize
 	tcpSACKEnabled bool
@@ -350,6 +351,16 @@ func (s *Stack) SetTCPSACKEnabled(enabled bool) error {
 	return syserror.EACCES
 }
 
+// TCPRecovery implements inet.Stack.TCPRecovery.
+func (s *Stack) TCPRecovery() (inet.TCPLossRecovery, error) {
+	return s.tcpRecovery, nil
+}
+
+// SetTCPRecovery implements inet.Stack.SetTCPRecovery.
+func (s *Stack) SetTCPRecovery(recovery inet.TCPLossRecovery) error {
+	return syserror.EACCES
+}
+
 // getLine reads one line from proc file, with specified prefix.
 // The last argument, withHeader, specifies if it contains line header.
 func getLine(f *os.File, prefix string, withHeader bool) string {
diff --git a/pkg/sentry/socket/netstack/stack.go b/pkg/sentry/socket/netstack/stack.go
index 67737ae87..f0fe18684 100644
--- a/pkg/sentry/socket/netstack/stack.go
+++ b/pkg/sentry/socket/netstack/stack.go
@@ -207,6 +207,20 @@ func (s *Stack) SetTCPSACKEnabled(enabled bool) error {
 	return syserr.TranslateNetstackError(s.Stack.SetTransportProtocolOption(tcp.ProtocolNumber, tcp.SACKEnabled(enabled))).ToError()
 }
 
+// TCPRecovery implements inet.Stack.TCPRecovery.
+func (s *Stack) TCPRecovery() (inet.TCPLossRecovery, error) {
+	var recovery tcp.Recovery
+	if err := s.Stack.TransportProtocolOption(tcp.ProtocolNumber, &recovery); err != nil {
+		return 0, syserr.TranslateNetstackError(err).ToError()
+	}
+	return inet.TCPLossRecovery(recovery), nil
+}
+
+// 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()
+}
+
 // Statistics implements inet.Stack.Statistics.
 func (s *Stack) Statistics(stat interface{}, arg string) error {
 	switch stats := stat.(type) {