Fix panic when logging raw packets via sniffer.

Sniffer assumed that outgoing packets have transport headers, but
users can write packets via SOCK_RAW with arbitrary transport headers that
netstack doesn't know about. We now explicitly check for the presence of network
and transport headers before assuming they exist.

PiperOrigin-RevId: 280594395

1 files changed, 140 insertions, 137 deletions

diff --git a/pkg/tcpip/link/sniffer/sniffer.go b/pkg/tcpip/link/sniffer/sniffer.go
index 122680e10..147d4e242 100644
--- a/pkg/tcpip/link/sniffer/sniffer.go
+++ b/pkg/tcpip/link/sniffer/sniffer.go
@@ -118,7 +118,7 @@ func NewWithFile(lower stack.LinkEndpoint, file *os.File, snapLen uint32) (stack
 // logs the packet before forwarding to the actual dispatcher.
 func (e *endpoint) DeliverNetworkPacket(linkEP stack.LinkEndpoint, remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt tcpip.PacketBuffer) {
 	if atomic.LoadUint32(&LogPackets) == 1 && e.file == nil {
-		logPacket("recv", protocol, pkt.Data.First(), nil)
+		logPacket("recv", protocol, pkt, nil)
 	}
 	if e.file != nil && atomic.LoadUint32(&LogPacketsToFile) == 1 {
 		vs := pkt.Data.Views()
@@ -195,7 +195,7 @@ func (e *endpoint) GSOMaxSize() uint32 {
 
 func (e *endpoint) dumpPacket(gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt tcpip.PacketBuffer) {
 	if atomic.LoadUint32(&LogPackets) == 1 && e.file == nil {
-		logPacket("send", protocol, pkt.Header.View(), gso)
+		logPacket("send", protocol, pkt, gso)
 	}
 	if e.file != nil && atomic.LoadUint32(&LogPacketsToFile) == 1 {
 		hdrBuf := pkt.Header.View()
@@ -247,7 +247,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, hdrs []stack.Pac
 // WriteRawPacket implements stack.LinkEndpoint.WriteRawPacket.
 func (e *endpoint) WriteRawPacket(vv buffer.VectorisedView) *tcpip.Error {
 	if atomic.LoadUint32(&LogPackets) == 1 && e.file == nil {
-		logPacket("send", 0, buffer.View("[raw packet, no header available]"), nil /* gso */)
+		logPacket("send raw packet", 0, tcpip.PacketBuffer{}, nil /* gso */)
 	}
 	if e.file != nil && atomic.LoadUint32(&LogPacketsToFile) == 1 {
 		length := vv.Size()
@@ -289,7 +289,7 @@ func logVectorisedView(vv buffer.VectorisedView, length int, buf *bytes.Buffer)
 // Wait implements stack.LinkEndpoint.Wait.
 func (*endpoint) Wait() {}
 
-func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, b buffer.View, gso *stack.GSO) {
+func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, pkt tcpip.PacketBuffer, gso *stack.GSO) {
 	// Figure out the network layer info.
 	var transProto uint8
 	src := tcpip.Address("unknown")
@@ -298,39 +298,40 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, b buffer.Vie
 	size := uint16(0)
 	var fragmentOffset uint16
 	var moreFragments bool
-	switch protocol {
-	case header.IPv4ProtocolNumber:
-		ipv4 := header.IPv4(b)
-		fragmentOffset = ipv4.FragmentOffset()
-		moreFragments = ipv4.Flags()&header.IPv4FlagMoreFragments == header.IPv4FlagMoreFragments
-		src = ipv4.SourceAddress()
-		dst = ipv4.DestinationAddress()
-		transProto = ipv4.Protocol()
-		size = ipv4.TotalLength() - uint16(ipv4.HeaderLength())
-		b = b[ipv4.HeaderLength():]
-		id = int(ipv4.ID())
-
-	case header.IPv6ProtocolNumber:
-		ipv6 := header.IPv6(b)
-		src = ipv6.SourceAddress()
-		dst = ipv6.DestinationAddress()
-		transProto = ipv6.NextHeader()
-		size = ipv6.PayloadLength()
-		b = b[header.IPv6MinimumSize:]
-
-	case header.ARPProtocolNumber:
-		arp := header.ARP(b)
-		log.Infof(
-			"%s arp %v (%v) -> %v (%v) valid:%v",
-			prefix,
-			tcpip.Address(arp.ProtocolAddressSender()), tcpip.LinkAddress(arp.HardwareAddressSender()),
-			tcpip.Address(arp.ProtocolAddressTarget()), tcpip.LinkAddress(arp.HardwareAddressTarget()),
-			arp.IsValid(),
-		)
-		return
-	default:
-		log.Infof("%s unknown network protocol", prefix)
-		return
+
+	if pkt.NetworkHeader != nil {
+		switch protocol {
+		case header.IPv4ProtocolNumber:
+			ipv4 := header.IPv4(pkt.NetworkHeader)
+			fragmentOffset = ipv4.FragmentOffset()
+			moreFragments = ipv4.Flags()&header.IPv4FlagMoreFragments == header.IPv4FlagMoreFragments
+			src = ipv4.SourceAddress()
+			dst = ipv4.DestinationAddress()
+			transProto = ipv4.Protocol()
+			size = ipv4.TotalLength() - uint16(ipv4.HeaderLength())
+			id = int(ipv4.ID())
+
+		case header.IPv6ProtocolNumber:
+			ipv6 := header.IPv6(pkt.NetworkHeader)
+			src = ipv6.SourceAddress()
+			dst = ipv6.DestinationAddress()
+			transProto = ipv6.NextHeader()
+			size = ipv6.PayloadLength()
+
+		case header.ARPProtocolNumber:
+			arp := header.ARP(pkt.NetworkHeader)
+			log.Infof(
+				"%s arp %v (%v) -> %v (%v) valid:%v",
+				prefix,
+				tcpip.Address(arp.ProtocolAddressSender()), tcpip.LinkAddress(arp.HardwareAddressSender()),
+				tcpip.Address(arp.ProtocolAddressTarget()), tcpip.LinkAddress(arp.HardwareAddressTarget()),
+				arp.IsValid(),
+			)
+			return
+		default:
+			log.Infof("%s unknown network protocol", prefix)
+			return
+		}
 	}
 
 	// Figure out the transport layer info.
@@ -338,118 +339,120 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, b buffer.Vie
 	srcPort := uint16(0)
 	dstPort := uint16(0)
 	details := ""
-	switch tcpip.TransportProtocolNumber(transProto) {
-	case header.ICMPv4ProtocolNumber:
-		transName = "icmp"
-		icmp := header.ICMPv4(b)
-		icmpType := "unknown"
-		if fragmentOffset == 0 {
+	if pkt.TransportHeader != nil {
+		switch tcpip.TransportProtocolNumber(transProto) {
+		case header.ICMPv4ProtocolNumber:
+			transName = "icmp"
+			icmp := header.ICMPv4(pkt.TransportHeader)
+			icmpType := "unknown"
+			if fragmentOffset == 0 {
+				switch icmp.Type() {
+				case header.ICMPv4EchoReply:
+					icmpType = "echo reply"
+				case header.ICMPv4DstUnreachable:
+					icmpType = "destination unreachable"
+				case header.ICMPv4SrcQuench:
+					icmpType = "source quench"
+				case header.ICMPv4Redirect:
+					icmpType = "redirect"
+				case header.ICMPv4Echo:
+					icmpType = "echo"
+				case header.ICMPv4TimeExceeded:
+					icmpType = "time exceeded"
+				case header.ICMPv4ParamProblem:
+					icmpType = "param problem"
+				case header.ICMPv4Timestamp:
+					icmpType = "timestamp"
+				case header.ICMPv4TimestampReply:
+					icmpType = "timestamp reply"
+				case header.ICMPv4InfoRequest:
+					icmpType = "info request"
+				case header.ICMPv4InfoReply:
+					icmpType = "info reply"
+				}
+			}
+			log.Infof("%s %s %v -> %v %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
+			return
+
+		case header.ICMPv6ProtocolNumber:
+			transName = "icmp"
+			icmp := header.ICMPv6(pkt.TransportHeader)
+			icmpType := "unknown"
 			switch icmp.Type() {
-			case header.ICMPv4EchoReply:
-				icmpType = "echo reply"
-			case header.ICMPv4DstUnreachable:
+			case header.ICMPv6DstUnreachable:
 				icmpType = "destination unreachable"
-			case header.ICMPv4SrcQuench:
-				icmpType = "source quench"
-			case header.ICMPv4Redirect:
-				icmpType = "redirect"
-			case header.ICMPv4Echo:
-				icmpType = "echo"
-			case header.ICMPv4TimeExceeded:
+			case header.ICMPv6PacketTooBig:
+				icmpType = "packet too big"
+			case header.ICMPv6TimeExceeded:
 				icmpType = "time exceeded"
-			case header.ICMPv4ParamProblem:
+			case header.ICMPv6ParamProblem:
 				icmpType = "param problem"
-			case header.ICMPv4Timestamp:
-				icmpType = "timestamp"
-			case header.ICMPv4TimestampReply:
-				icmpType = "timestamp reply"
-			case header.ICMPv4InfoRequest:
-				icmpType = "info request"
-			case header.ICMPv4InfoReply:
-				icmpType = "info reply"
+			case header.ICMPv6EchoRequest:
+				icmpType = "echo request"
+			case header.ICMPv6EchoReply:
+				icmpType = "echo reply"
+			case header.ICMPv6RouterSolicit:
+				icmpType = "router solicit"
+			case header.ICMPv6RouterAdvert:
+				icmpType = "router advert"
+			case header.ICMPv6NeighborSolicit:
+				icmpType = "neighbor solicit"
+			case header.ICMPv6NeighborAdvert:
+				icmpType = "neighbor advert"
+			case header.ICMPv6RedirectMsg:
+				icmpType = "redirect message"
 			}
-		}
-		log.Infof("%s %s %v -> %v %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
-		return
-
-	case header.ICMPv6ProtocolNumber:
-		transName = "icmp"
-		icmp := header.ICMPv6(b)
-		icmpType := "unknown"
-		switch icmp.Type() {
-		case header.ICMPv6DstUnreachable:
-			icmpType = "destination unreachable"
-		case header.ICMPv6PacketTooBig:
-			icmpType = "packet too big"
-		case header.ICMPv6TimeExceeded:
-			icmpType = "time exceeded"
-		case header.ICMPv6ParamProblem:
-			icmpType = "param problem"
-		case header.ICMPv6EchoRequest:
-			icmpType = "echo request"
-		case header.ICMPv6EchoReply:
-			icmpType = "echo reply"
-		case header.ICMPv6RouterSolicit:
-			icmpType = "router solicit"
-		case header.ICMPv6RouterAdvert:
-			icmpType = "router advert"
-		case header.ICMPv6NeighborSolicit:
-			icmpType = "neighbor solicit"
-		case header.ICMPv6NeighborAdvert:
-			icmpType = "neighbor advert"
-		case header.ICMPv6RedirectMsg:
-			icmpType = "redirect message"
-		}
-		log.Infof("%s %s %v -> %v %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
-		return
-
-	case header.UDPProtocolNumber:
-		transName = "udp"
-		udp := header.UDP(b)
-		if fragmentOffset == 0 && len(udp) >= header.UDPMinimumSize {
-			srcPort = udp.SourcePort()
-			dstPort = udp.DestinationPort()
-			details = fmt.Sprintf("xsum: 0x%x", udp.Checksum())
-			size -= header.UDPMinimumSize
-		}
+			log.Infof("%s %s %v -> %v %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
+			return
 
-	case header.TCPProtocolNumber:
-		transName = "tcp"
-		tcp := header.TCP(b)
-		if fragmentOffset == 0 && len(tcp) >= header.TCPMinimumSize {
-			offset := int(tcp.DataOffset())
-			if offset < header.TCPMinimumSize {
-				details += fmt.Sprintf("invalid packet: tcp data offset too small %d", offset)
-				break
-			}
-			if offset > len(tcp) && !moreFragments {
-				details += fmt.Sprintf("invalid packet: tcp data offset %d larger than packet buffer length %d", offset, len(tcp))
-				break
+		case header.UDPProtocolNumber:
+			transName = "udp"
+			udp := header.UDP(pkt.TransportHeader)
+			if fragmentOffset == 0 && len(udp) >= header.UDPMinimumSize {
+				srcPort = udp.SourcePort()
+				dstPort = udp.DestinationPort()
+				details = fmt.Sprintf("xsum: 0x%x", udp.Checksum())
+				size -= header.UDPMinimumSize
 			}
 
-			srcPort = tcp.SourcePort()
-			dstPort = tcp.DestinationPort()
-			size -= uint16(offset)
+		case header.TCPProtocolNumber:
+			transName = "tcp"
+			tcp := header.TCP(pkt.TransportHeader)
+			if fragmentOffset == 0 && len(tcp) >= header.TCPMinimumSize {
+				offset := int(tcp.DataOffset())
+				if offset < header.TCPMinimumSize {
+					details += fmt.Sprintf("invalid packet: tcp data offset too small %d", offset)
+					break
+				}
+				if offset > len(tcp) && !moreFragments {
+					details += fmt.Sprintf("invalid packet: tcp data offset %d larger than packet buffer length %d", offset, len(tcp))
+					break
+				}
 
-			// Initialize the TCP flags.
-			flags := tcp.Flags()
-			flagsStr := []byte("FSRPAU")
-			for i := range flagsStr {
-				if flags&(1<<uint(i)) == 0 {
-					flagsStr[i] = ' '
+				srcPort = tcp.SourcePort()
+				dstPort = tcp.DestinationPort()
+				size -= uint16(offset)
+
+				// Initialize the TCP flags.
+				flags := tcp.Flags()
+				flagsStr := []byte("FSRPAU")
+				for i := range flagsStr {
+					if flags&(1<<uint(i)) == 0 {
+						flagsStr[i] = ' '
+					}
+				}
+				details = fmt.Sprintf("flags:0x%02x (%v) seqnum: %v ack: %v win: %v xsum:0x%x", flags, string(flagsStr), tcp.SequenceNumber(), tcp.AckNumber(), tcp.WindowSize(), tcp.Checksum())
+				if flags&header.TCPFlagSyn != 0 {
+					details += fmt.Sprintf(" options: %+v", header.ParseSynOptions(tcp.Options(), flags&header.TCPFlagAck != 0))
+				} else {
+					details += fmt.Sprintf(" options: %+v", tcp.ParsedOptions())
 				}
 			}
-			details = fmt.Sprintf("flags:0x%02x (%v) seqnum: %v ack: %v win: %v xsum:0x%x", flags, string(flagsStr), tcp.SequenceNumber(), tcp.AckNumber(), tcp.WindowSize(), tcp.Checksum())
-			if flags&header.TCPFlagSyn != 0 {
-				details += fmt.Sprintf(" options: %+v", header.ParseSynOptions(tcp.Options(), flags&header.TCPFlagAck != 0))
-			} else {
-				details += fmt.Sprintf(" options: %+v", tcp.ParsedOptions())
-			}
-		}
 
-	default:
-		log.Infof("%s %v -> %v unknown transport protocol: %d", prefix, src, dst, transProto)
-		return
+		default:
+			log.Infof("%s %v -> %v unknown transport protocol: %d", prefix, src, dst, transProto)
+			return
+		}
 	}
 
 	if gso != nil {