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path: root/pkg/tcpip/transport/udp/protocol.go
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Diffstat (limited to 'pkg/tcpip/transport/udp/protocol.go')
-rw-r--r--pkg/tcpip/transport/udp/protocol.go101
1 files changed, 100 insertions, 1 deletions
diff --git a/pkg/tcpip/transport/udp/protocol.go b/pkg/tcpip/transport/udp/protocol.go
index f76e7fbe1..068d9a272 100644
--- a/pkg/tcpip/transport/udp/protocol.go
+++ b/pkg/tcpip/transport/udp/protocol.go
@@ -69,7 +69,106 @@ func (*protocol) ParsePorts(v buffer.View) (src, dst uint16, err *tcpip.Error) {
// HandleUnknownDestinationPacket handles packets targeted at this protocol but
// that don't match any existing endpoint.
-func (p *protocol) HandleUnknownDestinationPacket(*stack.Route, stack.TransportEndpointID, buffer.VectorisedView) bool {
+func (p *protocol) HandleUnknownDestinationPacket(r *stack.Route, id stack.TransportEndpointID, netHeader buffer.View, vv buffer.VectorisedView) bool {
+ // Get the header then trim it from the view.
+ hdr := header.UDP(vv.First())
+ if int(hdr.Length()) > vv.Size() {
+ // Malformed packet.
+ r.Stack().Stats().UDP.MalformedPacketsReceived.Increment()
+ return true
+ }
+ // TODO(b/129426613): only send an ICMP message if UDP checksum is valid.
+
+ // Only send ICMP error if the address is not a multicast/broadcast
+ // v4/v6 address or the source is not the unspecified address.
+ //
+ // See: point e) in https://tools.ietf.org/html/rfc4443#section-2.4
+ if id.LocalAddress == header.IPv4Broadcast || header.IsV4MulticastAddress(id.LocalAddress) || header.IsV6MulticastAddress(id.LocalAddress) || id.RemoteAddress == header.IPv6Any || id.RemoteAddress == header.IPv4Any {
+ return true
+ }
+
+ // As per RFC: 1122 Section 3.2.2.1 A host SHOULD generate Destination
+ // Unreachable messages with code:
+ //
+ // 2 (Protocol Unreachable), when the designated transport protocol
+ // is not supported; or
+ //
+ // 3 (Port Unreachable), when the designated transport protocol
+ // (e.g., UDP) is unable to demultiplex the datagram but has no
+ // protocol mechanism to inform the sender.
+ switch len(id.LocalAddress) {
+ case header.IPv4AddressSize:
+ if !r.Stack().AllowICMPMessage() {
+ r.Stack().Stats().ICMP.V4PacketsSent.RateLimited.Increment()
+ return true
+ }
+ // As per RFC 1812 Section 4.3.2.3
+ //
+ // ICMP datagram SHOULD contain as much of the original
+ // datagram as possible without the length of the ICMP
+ // datagram exceeding 576 bytes
+ //
+ // NOTE: The above RFC referenced is different from the original
+ // recommendation in RFC 1122 where it mentioned that at least 8
+ // bytes of the payload must be included. Today linux and other
+ // systems implement the] RFC1812 definition and not the original
+ // RFC 1122 requirement.
+ mtu := int(r.MTU())
+ if mtu > header.IPv4MinimumProcessableDatagramSize {
+ mtu = header.IPv4MinimumProcessableDatagramSize
+ }
+ headerLen := int(r.MaxHeaderLength()) + header.ICMPv4MinimumSize
+ available := int(mtu) - headerLen
+ payloadLen := len(netHeader) + vv.Size()
+ if payloadLen > available {
+ payloadLen = available
+ }
+
+ payload := buffer.NewVectorisedView(len(netHeader), []buffer.View{netHeader})
+ payload.Append(vv)
+ payload.CapLength(payloadLen)
+
+ hdr := buffer.NewPrependable(headerLen)
+ pkt := header.ICMPv4(hdr.Prepend(header.ICMPv4MinimumSize))
+ pkt.SetType(header.ICMPv4DstUnreachable)
+ pkt.SetCode(header.ICMPv4PortUnreachable)
+ pkt.SetChecksum(header.ICMPv4Checksum(pkt, payload))
+ r.WritePacket(nil /* gso */, hdr, payload, header.ICMPv4ProtocolNumber, r.DefaultTTL())
+
+ case header.IPv6AddressSize:
+ if !r.Stack().AllowICMPMessage() {
+ r.Stack().Stats().ICMP.V6PacketsSent.RateLimited.Increment()
+ return true
+ }
+
+ // As per RFC 4443 section 2.4
+ //
+ // (c) Every ICMPv6 error message (type < 128) MUST include
+ // as much of the IPv6 offending (invoking) packet (the
+ // packet that caused the error) as possible without making
+ // the error message packet exceed the minimum IPv6 MTU
+ // [IPv6].
+ mtu := int(r.MTU())
+ if mtu > header.IPv6MinimumMTU {
+ mtu = header.IPv6MinimumMTU
+ }
+ headerLen := int(r.MaxHeaderLength()) + header.ICMPv6DstUnreachableMinimumSize
+ available := int(mtu) - headerLen
+ payloadLen := len(netHeader) + vv.Size()
+ if payloadLen > available {
+ payloadLen = available
+ }
+ payload := buffer.NewVectorisedView(len(netHeader), []buffer.View{netHeader})
+ payload.Append(vv)
+ payload.CapLength(payloadLen)
+
+ hdr := buffer.NewPrependable(headerLen)
+ pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6DstUnreachableMinimumSize))
+ pkt.SetType(header.ICMPv6DstUnreachable)
+ pkt.SetCode(header.ICMPv6PortUnreachable)
+ pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, payload))
+ r.WritePacket(nil /* gso */, hdr, payload, header.ICMPv6ProtocolNumber, r.DefaultTTL())
+ }
return true
}