diff options
Diffstat (limited to 'pkg/tcpip/network/ipv6/ipv6.go')
| -rw-r--r-- | pkg/tcpip/network/ipv6/ipv6.go | 122 |
1 files changed, 117 insertions, 5 deletions
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go index 29e597002..a703a768c 100644 --- a/pkg/tcpip/network/ipv6/ipv6.go +++ b/pkg/tcpip/network/ipv6/ipv6.go @@ -21,11 +21,14 @@ package ipv6 import ( + "fmt" "sync/atomic" "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/buffer" "gvisor.dev/gvisor/pkg/tcpip/header" + "gvisor.dev/gvisor/pkg/tcpip/network/fragmentation" + "gvisor.dev/gvisor/pkg/tcpip/network/hash" "gvisor.dev/gvisor/pkg/tcpip/stack" ) @@ -49,6 +52,7 @@ type endpoint struct { linkEP stack.LinkEndpoint linkAddrCache stack.LinkAddressCache dispatcher stack.TransportDispatcher + fragmentation *fragmentation.Fragmentation protocol *protocol } @@ -172,6 +176,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt stack.PacketBuffer) { headerView := pkt.Data.First() h := header.IPv6(headerView) if !h.IsValid(pkt.Data.Size()) { + r.Stats().IP.MalformedPacketsReceived.Increment() return } @@ -179,14 +184,120 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt stack.PacketBuffer) { pkt.Data.TrimFront(header.IPv6MinimumSize) pkt.Data.CapLength(int(h.PayloadLength())) - p := h.TransportProtocol() - if p == header.ICMPv6ProtocolNumber { - e.handleICMP(r, headerView, pkt) + it, err := header.MakeIPv6PayloadIterator(header.IPv6ExtensionHeaderIdentifier(h.NextHeader()), pkt.Data, true) + if err != nil { + r.Stats().IP.MalformedPacketsReceived.Increment() return } - r.Stats().IP.PacketsDelivered.Increment() - e.dispatcher.DeliverTransportPacket(r, p, pkt) + for { + extHdr, done, err := it.Next() + if err != nil { + // This should never happen as MakeIPv6PayloadIterator above did not + // return an error. + panic(fmt.Sprintf("unexpected error when iterating over IPv6 payload: %s", err)) + } + if done { + break + } + + switch extHdr := extHdr.(type) { + case header.IPv6RoutingExtHdr: + // As per RFC 8200 section 4.4, if a node encounters a routing header with + // an unrecognized routing type value, with a non-zero Segments Left + // value, the node must discard the packet and send an ICMP Parameter + // Problem, Code 0. If the Segments Left is 0, the node must ignore the + // Routing extension header and process the next header in the packet. + // + // Note, the stack does not yet handle any type of routing extension + // header, so we just make sure Segments Left is zero before processing + // the next extension header. + // + // TODO(b/152019344): Send an ICMPv6 Parameter Problem Code 0 for + // unrecognized routing types with a non-zero Segments Left value. + if extHdr.SegmentsLeft() != 0 { + return + } + + case header.IPv6FragmentExtHdr: + fragmentOffset := extHdr.FragmentOffset() + more := extHdr.More() + if !more && fragmentOffset == 0 { + // This fragment extension header indicates that this packet is an + // atomic fragment. An atomic fragment is a fragment that contains + // all the data required to reassemble a full packet. As per RFC 6946, + // atomic fragments must not interfere with "normal" fragmented traffic + // so we skip processing the fragment instead of feeding it through the + // reassembly process below. + continue + } + + rawPayload := it.AsRawHeader() + fragmentPayloadLen := rawPayload.Buf.Size() + if fragmentPayloadLen == 0 { + // Drop the packet as it's marked as a fragment but has no payload. + r.Stats().IP.MalformedPacketsReceived.Increment() + r.Stats().IP.MalformedFragmentsReceived.Increment() + return + } + + // The packet is a fragment, let's try to reassemble it. + start := fragmentOffset * header.IPv6FragmentExtHdrFragmentOffsetBytesPerUnit + last := start + uint16(fragmentPayloadLen) - 1 + + // Drop the packet if the fragmentOffset is incorrect. i.e the + // combination of fragmentOffset and pkt.Data.size() causes a + // wrap around resulting in last being less than the offset. + if last < start { + r.Stats().IP.MalformedPacketsReceived.Increment() + r.Stats().IP.MalformedFragmentsReceived.Increment() + return + } + + var ready bool + pkt.Data, ready, err = e.fragmentation.Process(hash.IPv6FragmentHash(h, extHdr.ID()), start, last, more, rawPayload.Buf) + if err != nil { + r.Stats().IP.MalformedPacketsReceived.Increment() + r.Stats().IP.MalformedFragmentsReceived.Increment() + return + } + + if ready { + // We create a new iterator with the reassembled packet because we could + // have more extension headers in the reassembled payload, as per RFC + // 8200 section 4.5. + it, err = header.MakeIPv6PayloadIterator(rawPayload.Identifier, pkt.Data, true) + if err != nil { + r.Stats().IP.MalformedPacketsReceived.Increment() + r.Stats().IP.MalformedFragmentsReceived.Increment() + return + } + } + + case header.IPv6RawPayloadHeader: + // If the last header in the payload isn't a known IPv6 extension header, + // handle it as if it is transport layer data. + pkt.Data = extHdr.Buf + + if p := tcpip.TransportProtocolNumber(extHdr.Identifier); p == header.ICMPv6ProtocolNumber { + e.handleICMP(r, headerView, pkt) + } else { + r.Stats().IP.PacketsDelivered.Increment() + // TODO(b/152019344): Send an ICMPv6 Parameter Problem, Code 1 error + // in response to unrecognized next header values. + e.dispatcher.DeliverTransportPacket(r, p, pkt) + } + + default: + // If we receive a packet for an extension header we do not yet handle, + // drop the packet for now. + // + // TODO(b/152019344): Send an ICMPv6 Parameter Problem, Code 1 error + // in response to unrecognized next header values. + r.Stats().UnknownProtocolRcvdPackets.Increment() + return + } + } } // Close cleans up resources associated with the endpoint. @@ -229,6 +340,7 @@ func (p *protocol) NewEndpoint(nicID tcpip.NICID, addrWithPrefix tcpip.AddressWi linkEP: linkEP, linkAddrCache: linkAddrCache, dispatcher: dispatcher, + fragmentation: fragmentation.NewFragmentation(fragmentation.HighFragThreshold, fragmentation.LowFragThreshold, fragmentation.DefaultReassembleTimeout), protocol: p, }, nil } |