Only carry GSO options in the packet buffer

With this change, GSO options no longer needs to be passed around as
a function argument in the write path.

This change is done in preparation for a later change that defers
segmentation, and may change GSO options for a packet as it flows
down the stack.

Updates #170.

PiperOrigin-RevId: 369774872

4 files changed, 28 insertions, 48 deletions

diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go
index 1525f15db..f663fdc0b 100644
--- a/pkg/tcpip/network/ipv4/icmp.go
+++ b/pkg/tcpip/network/ipv4/icmp.go
@@ -629,7 +629,6 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) tcpip
 	icmpHdr.SetChecksum(header.ICMPv4Checksum(icmpHdr, icmpPkt.Data().AsRange().Checksum()))
 
 	if err := route.WritePacket(
-		nil, /* gso */
 		stack.NetworkHeaderParams{
 			Protocol: header.ICMPv4ProtocolNumber,
 			TTL:      route.DefaultTTL(),
diff --git a/pkg/tcpip/network/ipv4/igmp.go b/pkg/tcpip/network/ipv4/igmp.go
index b1ac29294..3ce499298 100644
--- a/pkg/tcpip/network/ipv4/igmp.go
+++ b/pkg/tcpip/network/ipv4/igmp.go
@@ -341,7 +341,7 @@ func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip
 	}
 
 	sentStats := igmp.ep.stats.igmp.packetsSent
-	if err := igmp.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv4Address(destAddress), nil /* gso */, ProtocolNumber, pkt); err != nil {
+	if err := igmp.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv4Address(destAddress), ProtocolNumber, pkt); err != nil {
 		sentStats.dropped.Increment()
 		return false, err
 	}
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index a82a5790d..a0bc06465 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -350,7 +350,7 @@ func (e *endpoint) addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.Packet
 // fragment. It returns the number of fragments handled and the number of
 // fragments left to be processed. The IP header must already be present in the
 // original packet.
-func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, networkMTU uint32, pkt *stack.PacketBuffer, handler func(*stack.PacketBuffer) tcpip.Error) (int, int, tcpip.Error) {
+func (e *endpoint) handleFragments(r *stack.Route, networkMTU uint32, pkt *stack.PacketBuffer, handler func(*stack.PacketBuffer) tcpip.Error) (int, int, tcpip.Error) {
 	// Round the MTU down to align to 8 bytes.
 	fragmentPayloadSize := networkMTU &^ 7
 	networkHeader := header.IPv4(pkt.NetworkHeader().View())
@@ -370,7 +370,7 @@ func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, networkMTU ui
 }
 
 // WritePacket writes a packet to the given destination address and protocol.
-func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) tcpip.Error {
+func (e *endpoint) WritePacket(r *stack.Route, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) tcpip.Error {
 	if err := e.addIPHeader(r.LocalAddress(), r.RemoteAddress(), pkt, params, nil /* options */); err != nil {
 		return err
 	}
@@ -378,7 +378,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 	// iptables filtering. All packets that reach here are locally
 	// generated.
 	outNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
-	if ok := e.protocol.stack.IPTables().Check(stack.Output, pkt, gso, r, "" /* preroutingAddr */, "" /* inNicName */, outNicName); !ok {
+	if ok := e.protocol.stack.IPTables().Check(stack.Output, pkt, r, "" /* preroutingAddr */, "" /* inNicName */, outNicName); !ok {
 		// iptables is telling us to drop the packet.
 		e.stats.ip.IPTablesOutputDropped.Increment()
 		return nil
@@ -401,10 +401,10 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
 		}
 	}
 
-	return e.writePacket(r, gso, pkt, false /* headerIncluded */)
+	return e.writePacket(r, pkt, false /* headerIncluded */)
 }
 
-func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.PacketBuffer, headerIncluded bool) tcpip.Error {
+func (e *endpoint) writePacket(r *stack.Route, pkt *stack.PacketBuffer, headerIncluded bool) tcpip.Error {
 	if r.Loop()&stack.PacketLoop != 0 {
 		// If the packet was generated by the stack (not a raw/packet endpoint
 		// where a packet may be written with the header included), then we can
@@ -418,7 +418,7 @@ func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.Packet
 	// Postrouting NAT can only change the source address, and does not alter the
 	// route or outgoing interface of the packet.
 	outNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
-	if ok := e.protocol.stack.IPTables().Check(stack.Postrouting, pkt, gso, r, "" /* preroutingAddr */, "" /* inNicName */, outNicName); !ok {
+	if ok := e.protocol.stack.IPTables().Check(stack.Postrouting, pkt, r, "" /* preroutingAddr */, "" /* inNicName */, outNicName); !ok {
 		// iptables is telling us to drop the packet.
 		e.stats.ip.IPTablesPostroutingDropped.Increment()
 		return nil
@@ -432,20 +432,20 @@ func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.Packet
 		return err
 	}
 
-	if packetMustBeFragmented(pkt, networkMTU, gso) {
-		sent, remain, err := e.handleFragments(r, gso, networkMTU, pkt, func(fragPkt *stack.PacketBuffer) tcpip.Error {
+	if packetMustBeFragmented(pkt, networkMTU) {
+		sent, remain, err := e.handleFragments(r, networkMTU, pkt, func(fragPkt *stack.PacketBuffer) tcpip.Error {
 			// TODO(gvisor.dev/issue/3884): Evaluate whether we want to send each
 			// fragment one by one using WritePacket() (current strategy) or if we
 			// want to create a PacketBufferList from the fragments and feed it to
 			// WritePackets(). It'll be faster but cost more memory.
-			return e.nic.WritePacket(r, gso, ProtocolNumber, fragPkt)
+			return e.nic.WritePacket(r, ProtocolNumber, fragPkt)
 		})
 		stats.PacketsSent.IncrementBy(uint64(sent))
 		stats.OutgoingPacketErrors.IncrementBy(uint64(remain))
 		return err
 	}
 
-	if err := e.nic.WritePacket(r, gso, ProtocolNumber, pkt); err != nil {
+	if err := e.nic.WritePacket(r, ProtocolNumber, pkt); err != nil {
 		stats.OutgoingPacketErrors.Increment()
 		return err
 	}
@@ -454,7 +454,7 @@ func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.Packet
 }
 
 // WritePackets implements stack.NetworkEndpoint.WritePackets.
-func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.PacketBufferList, params stack.NetworkHeaderParams) (int, tcpip.Error) {
+func (e *endpoint) WritePackets(r *stack.Route, pkts stack.PacketBufferList, params stack.NetworkHeaderParams) (int, tcpip.Error) {
 	if r.Loop()&stack.PacketLoop != 0 {
 		panic("multiple packets in local loop")
 	}
@@ -475,11 +475,11 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 			return 0, err
 		}
 
-		if packetMustBeFragmented(pkt, networkMTU, gso) {
+		if packetMustBeFragmented(pkt, networkMTU) {
 			// Keep track of the packet that is about to be fragmented so it can be
 			// removed once the fragmentation is done.
 			originalPkt := pkt
-			if _, _, err := e.handleFragments(r, gso, networkMTU, pkt, func(fragPkt *stack.PacketBuffer) tcpip.Error {
+			if _, _, err := e.handleFragments(r, networkMTU, pkt, func(fragPkt *stack.PacketBuffer) tcpip.Error {
 				// Modify the packet list in place with the new fragments.
 				pkts.InsertAfter(pkt, fragPkt)
 				pkt = fragPkt
@@ -495,7 +495,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 	outNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
 	// iptables filtering. All packets that reach here are locally
 	// generated.
-	outputDropped, natPkts := e.protocol.stack.IPTables().CheckPackets(stack.Output, pkts, gso, r, "" /* inNicName */, outNicName)
+	outputDropped, natPkts := e.protocol.stack.IPTables().CheckPackets(stack.Output, pkts, r, "" /* inNicName */, outNicName)
 	stats.IPTablesOutputDropped.IncrementBy(uint64(len(outputDropped)))
 	for pkt := range outputDropped {
 		pkts.Remove(pkt)
@@ -522,7 +522,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 	// We ignore the list of NAT-ed packets here because Postrouting NAT can only
 	// change the source address, and does not alter the route or outgoing
 	// interface of the packet.
-	postroutingDropped, _ := e.protocol.stack.IPTables().CheckPackets(stack.Postrouting, pkts, gso, r, "" /* inNicName */, outNicName)
+	postroutingDropped, _ := e.protocol.stack.IPTables().CheckPackets(stack.Postrouting, pkts, r, "" /* inNicName */, outNicName)
 	stats.IPTablesPostroutingDropped.IncrementBy(uint64(len(postroutingDropped)))
 	for pkt := range postroutingDropped {
 		pkts.Remove(pkt)
@@ -530,7 +530,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 
 	// The rest of the packets can be delivered to the NIC as a batch.
 	pktsLen := pkts.Len()
-	written, err := e.nic.WritePackets(r, gso, pkts, ProtocolNumber)
+	written, err := e.nic.WritePackets(r, pkts, ProtocolNumber)
 	stats.PacketsSent.IncrementBy(uint64(written))
 	stats.OutgoingPacketErrors.IncrementBy(uint64(pktsLen - written))
 
@@ -595,7 +595,7 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu
 		return &tcpip.ErrMalformedHeader{}
 	}
 
-	return e.writePacket(r, nil /* gso */, pkt, true /* headerIncluded */)
+	return e.writePacket(r, pkt, true /* headerIncluded */)
 }
 
 // forwardPacket attempts to forward a packet to its final destination.
@@ -732,7 +732,7 @@ func (e *endpoint) HandlePacket(pkt *stack.PacketBuffer) {
 
 		// Loopback traffic skips the prerouting chain.
 		inNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
-		if ok := e.protocol.stack.IPTables().Check(stack.Prerouting, pkt, nil, nil, e.MainAddress().Address, inNicName, "" /* outNicName */); !ok {
+		if ok := e.protocol.stack.IPTables().Check(stack.Prerouting, pkt, nil, e.MainAddress().Address, inNicName, "" /* outNicName */); !ok {
 			// iptables is telling us to drop the packet.
 			stats.IPTablesPreroutingDropped.Increment()
 			return
@@ -805,7 +805,7 @@ func (e *endpoint) handleValidatedPacket(h header.IPv4, pkt *stack.PacketBuffer)
 	// iptables filtering. All packets that reach here are intended for
 	// this machine and will not be forwarded.
 	inNicName := e.protocol.stack.FindNICNameFromID(e.nic.ID())
-	if ok := e.protocol.stack.IPTables().Check(stack.Input, pkt, nil, nil, "" /* preroutingAddr */, inNicName, "" /* outNicName */); !ok {
+	if ok := e.protocol.stack.IPTables().Check(stack.Input, pkt, nil, "" /* preroutingAddr */, inNicName, "" /* outNicName */); !ok {
 		// iptables is telling us to drop the packet.
 		stats.ip.IPTablesInputDropped.Increment()
 		return
@@ -1258,9 +1258,9 @@ func calculateNetworkMTU(linkMTU, networkHeaderSize uint32) (uint32, tcpip.Error
 	return networkMTU - uint32(networkHeaderSize), nil
 }
 
-func packetMustBeFragmented(pkt *stack.PacketBuffer, networkMTU uint32, gso *stack.GSO) bool {
+func packetMustBeFragmented(pkt *stack.PacketBuffer, networkMTU uint32) bool {
 	payload := pkt.TransportHeader().View().Size() + pkt.Data().Size()
-	return (gso == nil || gso.Type == stack.GSONone) && uint32(payload) > networkMTU
+	return pkt.GSOOptions.Type == stack.GSONone && uint32(payload) > networkMTU
 }
 
 // addressToUint32 translates an IPv4 address into its little endian uint32
diff --git a/pkg/tcpip/network/ipv4/ipv4_test.go b/pkg/tcpip/network/ipv4/ipv4_test.go
index d49dff4d5..7d413c455 100644
--- a/pkg/tcpip/network/ipv4/ipv4_test.go
+++ b/pkg/tcpip/network/ipv4/ipv4_test.go
@@ -1242,7 +1242,6 @@ type fragmentInfo struct {
 var fragmentationTests = []struct {
 	description           string
 	mtu                   uint32
-	gso                   *stack.GSO
 	transportHeaderLength int
 	payloadSize           int
 	wantFragments         []fragmentInfo
@@ -1250,7 +1249,6 @@ var fragmentationTests = []struct {
 	{
 		description:           "No fragmentation",
 		mtu:                   1280,
-		gso:                   nil,
 		transportHeaderLength: 0,
 		payloadSize:           1000,
 		wantFragments: []fragmentInfo{
@@ -1260,7 +1258,6 @@ var fragmentationTests = []struct {
 	{
 		description:           "Fragmented",
 		mtu:                   1280,
-		gso:                   nil,
 		transportHeaderLength: 0,
 		payloadSize:           2000,
 		wantFragments: []fragmentInfo{
@@ -1271,7 +1268,6 @@ var fragmentationTests = []struct {
 	{
 		description:           "Fragmented with the minimum mtu",
 		mtu:                   header.IPv4MinimumMTU,
-		gso:                   nil,
 		transportHeaderLength: 0,
 		payloadSize:           100,
 		wantFragments: []fragmentInfo{
@@ -1283,7 +1279,6 @@ var fragmentationTests = []struct {
 	{
 		description:           "Fragmented with mtu not a multiple of 8",
 		mtu:                   header.IPv4MinimumMTU + 1,
-		gso:                   nil,
 		transportHeaderLength: 0,
 		payloadSize:           100,
 		wantFragments: []fragmentInfo{
@@ -1295,7 +1290,6 @@ var fragmentationTests = []struct {
 	{
 		description:           "No fragmentation with big header",
 		mtu:                   2000,
-		gso:                   nil,
 		transportHeaderLength: 100,
 		payloadSize:           1000,
 		wantFragments: []fragmentInfo{
@@ -1303,20 +1297,8 @@ var fragmentationTests = []struct {
 		},
 	},
 	{
-		description:           "Fragmented with gso none",
-		mtu:                   1280,
-		gso:                   &stack.GSO{Type: stack.GSONone},
-		transportHeaderLength: 0,
-		payloadSize:           1400,
-		wantFragments: []fragmentInfo{
-			{offset: 0, payloadSize: 1256, more: true},
-			{offset: 1256, payloadSize: 144, more: false},
-		},
-	},
-	{
 		description:           "Fragmented with big header",
 		mtu:                   1280,
-		gso:                   nil,
 		transportHeaderLength: 100,
 		payloadSize:           1200,
 		wantFragments: []fragmentInfo{
@@ -1327,7 +1309,6 @@ var fragmentationTests = []struct {
 	{
 		description:           "Fragmented with MTU smaller than header",
 		mtu:                   300,
-		gso:                   nil,
 		transportHeaderLength: 1000,
 		payloadSize:           500,
 		wantFragments: []fragmentInfo{
@@ -1350,13 +1331,13 @@ func TestFragmentationWritePacket(t *testing.T) {
 			r := buildRoute(t, ep)
 			pkt := testutil.MakeRandPkt(ft.transportHeaderLength, extraHeaderReserve+header.IPv4MinimumSize, []int{ft.payloadSize}, header.IPv4ProtocolNumber)
 			source := pkt.Clone()
-			err := r.WritePacket(ft.gso, stack.NetworkHeaderParams{
+			err := r.WritePacket(stack.NetworkHeaderParams{
 				Protocol: tcp.ProtocolNumber,
 				TTL:      ttl,
 				TOS:      stack.DefaultTOS,
 			}, pkt)
 			if err != nil {
-				t.Fatalf("r.WritePacket(_, _, _) = %s", err)
+				t.Fatalf("r.WritePacket(...): %s", err)
 			}
 			if got := len(ep.WrittenPackets); got != len(ft.wantFragments) {
 				t.Errorf("got len(ep.WrittenPackets) = %d, want = %d", got, len(ft.wantFragments))
@@ -1422,7 +1403,7 @@ func TestFragmentationWritePackets(t *testing.T) {
 					r := buildRoute(t, ep)
 
 					wantTotalPackets := len(ft.wantFragments) + test.insertBefore + test.insertAfter
-					n, err := r.WritePackets(ft.gso, pkts, stack.NetworkHeaderParams{
+					n, err := r.WritePackets(pkts, stack.NetworkHeaderParams{
 						Protocol: tcp.ProtocolNumber,
 						TTL:      ttl,
 						TOS:      stack.DefaultTOS,
@@ -1529,7 +1510,7 @@ func TestFragmentationErrors(t *testing.T) {
 			pkt := testutil.MakeRandPkt(ft.transportHeaderLength, extraHeaderReserve+header.IPv4MinimumSize, []int{ft.payloadSize}, header.IPv4ProtocolNumber)
 			ep := testutil.NewMockLinkEndpoint(ft.mtu, ft.mockError, ft.allowPackets)
 			r := buildRoute(t, ep)
-			err := r.WritePacket(&stack.GSO{}, stack.NetworkHeaderParams{
+			err := r.WritePacket(stack.NetworkHeaderParams{
 				Protocol: tcp.ProtocolNumber,
 				TTL:      ttl,
 				TOS:      stack.DefaultTOS,
@@ -2729,7 +2710,7 @@ func TestWriteStats(t *testing.T) {
 			writePackets: func(rt *stack.Route, pkts stack.PacketBufferList) (int, tcpip.Error) {
 				nWritten := 0
 				for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() {
-					if err := rt.WritePacket(nil, stack.NetworkHeaderParams{}, pkt); err != nil {
+					if err := rt.WritePacket(stack.NetworkHeaderParams{}, pkt); err != nil {
 						return nWritten, err
 					}
 					nWritten++
@@ -2739,7 +2720,7 @@ func TestWriteStats(t *testing.T) {
 		}, {
 			name: "WritePackets",
 			writePackets: func(rt *stack.Route, pkts stack.PacketBufferList) (int, tcpip.Error) {
-				return rt.WritePackets(nil, pkts, stack.NetworkHeaderParams{})
+				return rt.WritePackets(pkts, stack.NetworkHeaderParams{})
 			},
 		},
 	}