Fix: google/gvisor@f33d034 (google/gvisor#7125)

core/device/tun/tun_netstack.go

@@ -55,12 +55,15 @@ func Open(name string, mtu uint32) (device.Device, error) {
 		EthernetHeader: false,
 		// SYS_READV support only for TUN fd.
 		PacketDispatchMode: fdbased.Readv,
-		// TODO: set this field to zero in the future.
-		// it's a only temporary hack to avoid `socket operation
-		// on non-socket` error caused by SYS_SENDMMSG syscall.
+		// TAP/TUN fd's are not sockets and using the WritePackets calls results
+		// in errors as it always defaults to using SendMMsg which is not supported
+		// for tap/tun device fds.
 		//
-		// Ref: https://github.com/google/gvisor/issues/7125
-		MaxSyscallHeaderBytes: 0x40,
+		// This CL changes WritePackets to gracefully degrade to using writev instead
+		// of sendmmsg if the underlying fd is not a socket.
+		//
+		// Fixed: https://github.com/google/gvisor/commit/f33d034fecd7723a1e560ccc62aeeba328454fd0
+		MaxSyscallHeaderBytes: 0x00,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("create endpoint: %w", err)

go.mod

@@ -17,7 +17,7 @@ require (
 	golang.org/x/time v0.0.0-20211116232009-f0f3c7e86c11
 	golang.zx2c4.com/wireguard v0.0.0-20220202223031-3b95c81cc178
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b
-	gvisor.dev/gvisor v0.0.0-20220205064904-d09fa42eaa20
+	gvisor.dev/gvisor v0.0.0-20220208035940-56a131734b85
 )
 
 require (

go.sum

@@ -60,5 +60,5 @@ gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
 gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gvisor.dev/gvisor v0.0.0-20220205064904-d09fa42eaa20 h1:Aih4gc0gDmeT48uWlEuR7kl8AjqHR6buUV2kfjPzC0Y=
-gvisor.dev/gvisor v0.0.0-20220205064904-d09fa42eaa20/go.mod h1:V4WNP2Uwtx69eOhvLDSQ734EaTJTaBI3P8KgRAlROsg=
+gvisor.dev/gvisor v0.0.0-20220208035940-56a131734b85 h1:BELDz7P8Bn3BMDa9NYMDGATVO+F1fd/Pvr3Z2oisCvI=
+gvisor.dev/gvisor v0.0.0-20220208035940-56a131734b85/go.mod h1:V4WNP2Uwtx69eOhvLDSQ734EaTJTaBI3P8KgRAlROsg=