3 files changed, 56 insertions, 2 deletions
diff --git a/pkg/sentry/inet/BUILD b/pkg/sentry/inet/BUILD
index 07bf39fed..5bba9de0b 100644
--- a/pkg/sentry/inet/BUILD
+++ b/pkg/sentry/inet/BUILD
@@ -15,6 +15,7 @@ go_library(
     ],
     deps = [
         "//pkg/context",
+        "//pkg/tcpip",
         "//pkg/tcpip/stack",
     ],
 )
diff --git a/pkg/sentry/inet/inet.go b/pkg/sentry/inet/inet.go
index 2916a0644..fbe6d6aa6 100644
--- a/pkg/sentry/inet/inet.go
+++ b/pkg/sentry/inet/inet.go
@@ -15,7 +15,10 @@
 // Package inet defines semantics for IP stacks.
 package inet
 
-import "gvisor.dev/gvisor/pkg/tcpip/stack"
+import (
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+)
 
 // Stack represents a TCP/IP stack.
 type Stack interface {
@@ -56,6 +59,12 @@ type Stack interface {
 	// settings.
 	SetTCPSACKEnabled(enabled bool) error
 
+	// TCPRecovery returns the TCP loss detection algorithm.
+	TCPRecovery() (TCPLossRecovery, error)
+
+	// SetTCPRecovery attempts to change TCP loss detection algorithm.
+	SetTCPRecovery(recovery TCPLossRecovery) error
+
 	// Statistics reports stack statistics.
 	Statistics(stat interface{}, arg string) error
 
@@ -74,6 +83,12 @@ type Stack interface {
 	// RestoreCleanupEndpoints adds endpoints to cleanup tracking. This is useful
 	// for restoring a stack after a save.
 	RestoreCleanupEndpoints([]stack.TransportEndpoint)
+
+	// Forwarding returns if packet forwarding between NICs is enabled.
+	Forwarding(protocol tcpip.NetworkProtocolNumber) bool
+
+	// SetForwarding enables or disables packet forwarding between NICs.
+	SetForwarding(protocol tcpip.NetworkProtocolNumber, enable bool) error
 }
 
 // Interface contains information about a network interface.
@@ -189,3 +204,14 @@ type StatSNMPUDP [8]uint64
 
 // StatSNMPUDPLite describes UdpLite line of /proc/net/snmp.
 type StatSNMPUDPLite [8]uint64
+
+// TCPLossRecovery indicates TCP loss detection and recovery methods to use.
+type TCPLossRecovery int32
+
+// Loss recovery constants from include/net/tcp.h which are used to set
+// /proc/sys/net/ipv4/tcp_recovery.
+const (
+	TCP_RACK_LOSS_DETECTION TCPLossRecovery = 1 << iota
+	TCP_RACK_STATIC_REO_WND
+	TCP_RACK_NO_DUPTHRESH
+)
diff --git a/pkg/sentry/inet/test_stack.go b/pkg/sentry/inet/test_stack.go
index d8961fc94..1779cc6f3 100644
--- a/pkg/sentry/inet/test_stack.go
+++ b/pkg/sentry/inet/test_stack.go
@@ -14,7 +14,10 @@
 
 package inet
 
-import "gvisor.dev/gvisor/pkg/tcpip/stack"
+import (
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+)
 
 // TestStack is a dummy implementation of Stack for tests.
 type TestStack struct {
@@ -25,6 +28,8 @@ type TestStack struct {
 	TCPRecvBufSize    TCPBufferSize
 	TCPSendBufSize    TCPBufferSize
 	TCPSACKFlag       bool
+	Recovery          TCPLossRecovery
+	IPForwarding      bool
 }
 
 // NewTestStack returns a TestStack with no network interfaces. The value of
@@ -91,6 +96,17 @@ func (s *TestStack) SetTCPSACKEnabled(enabled bool) error {
 	return nil
 }
 
+// TCPRecovery implements Stack.TCPRecovery.
+func (s *TestStack) TCPRecovery() (TCPLossRecovery, error) {
+	return s.Recovery, nil
+}
+
+// SetTCPRecovery implements Stack.SetTCPRecovery.
+func (s *TestStack) SetTCPRecovery(recovery TCPLossRecovery) error {
+	s.Recovery = recovery
+	return nil
+}
+
 // Statistics implements inet.Stack.Statistics.
 func (s *TestStack) Statistics(stat interface{}, arg string) error {
 	return nil
@@ -116,3 +132,14 @@ func (s *TestStack) CleanupEndpoints() []stack.TransportEndpoint {
 
 // RestoreCleanupEndpoints implements inet.Stack.RestoreCleanupEndpoints.
 func (s *TestStack) RestoreCleanupEndpoints([]stack.TransportEndpoint) {}
+
+// Forwarding implements inet.Stack.Forwarding.
+func (s *TestStack) Forwarding(protocol tcpip.NetworkProtocolNumber) bool {
+	return s.IPForwarding
+}
+
+// SetForwarding implements inet.Stack.SetForwarding.
+func (s *TestStack) SetForwarding(protocol tcpip.NetworkProtocolNumber, enable bool) error {
+	s.IPForwarding = enable
+	return nil
+}