icmp: When setting TransportHeader, remove from the Data portion.

The current convention is when a header is set to pkt.XxxHeader field, it
gets removed from pkt.Data. ICMP does not currently follow this convention.

PiperOrigin-RevId: 320078606

2 files changed, 12 insertions, 7 deletions

diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index afb7dfeaf..7b80534e6 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -1358,16 +1358,19 @@ func (n *NIC) DeliverTransportPacket(r *Route, protocol tcpip.TransportProtocolN
 	// TransportHeader is nil only when pkt is an ICMP packet or was reassembled
 	// from fragments.
 	if pkt.TransportHeader == nil {
-		// TODO(gvisor.dev/issue/170): ICMP packets don't have their
-		// TransportHeader fields set. See icmp/protocol.go:protocol.Parse for a
+		// TODO(gvisor.dev/issue/170): ICMP packets don't have their TransportHeader
+		// fields set yet, parse it here. See icmp/protocol.go:protocol.Parse for a
 		// full explanation.
 		if protocol == header.ICMPv4ProtocolNumber || protocol == header.ICMPv6ProtocolNumber {
+			// ICMP packets may be longer, but until icmp.Parse is implemented, here
+			// we parse it using the minimum size.
 			transHeader, ok := pkt.Data.PullUp(transProto.MinimumPacketSize())
 			if !ok {
 				n.stack.stats.MalformedRcvdPackets.Increment()
 				return
 			}
 			pkt.TransportHeader = transHeader
+			pkt.Data.TrimFront(len(pkt.TransportHeader))
 		} else {
 			// This is either a bad packet or was re-assembled from fragments.
 			transProto.Parse(pkt)
diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index 8ce294002..62d1acad4 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -744,15 +744,15 @@ func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, pk
 	// Only accept echo replies.
 	switch e.NetProto {
 	case header.IPv4ProtocolNumber:
-		h, ok := pkt.Data.PullUp(header.ICMPv4MinimumSize)
-		if !ok || header.ICMPv4(h).Type() != header.ICMPv4EchoReply {
+		h := header.ICMPv4(pkt.TransportHeader)
+		if len(h) < header.ICMPv4MinimumSize || h.Type() != header.ICMPv4EchoReply {
 			e.stack.Stats().DroppedPackets.Increment()
 			e.stats.ReceiveErrors.MalformedPacketsReceived.Increment()
 			return
 		}
 	case header.IPv6ProtocolNumber:
-		h, ok := pkt.Data.PullUp(header.ICMPv6MinimumSize)
-		if !ok || header.ICMPv6(h).Type() != header.ICMPv6EchoReply {
+		h := header.ICMPv6(pkt.TransportHeader)
+		if len(h) < header.ICMPv6MinimumSize || h.Type() != header.ICMPv6EchoReply {
 			e.stack.Stats().DroppedPackets.Increment()
 			e.stats.ReceiveErrors.MalformedPacketsReceived.Increment()
 			return
@@ -786,7 +786,9 @@ func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, pk
 		},
 	}
 
-	packet.data = pkt.Data
+	// ICMP socket's data includes ICMP header.
+	packet.data = pkt.TransportHeader.ToVectorisedView()
+	packet.data.Append(pkt.Data)
 
 	e.rcvList.PushBack(packet)
 	e.rcvBufSize += packet.data.Size()