diff options
Diffstat (limited to 'pkg/tcpip/network/ipv6/icmp.go')
| -rw-r--r-- | pkg/tcpip/network/ipv6/icmp.go | 509 |
1 files changed, 343 insertions, 166 deletions
diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go index c3f1dd488..66d3a953a 100644 --- a/pkg/tcpip/network/ipv6/icmp.go +++ b/pkg/tcpip/network/ipv6/icmp.go @@ -15,6 +15,8 @@ package ipv6 import ( + "fmt" + "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/buffer" "gvisor.dev/gvisor/pkg/tcpip/header" @@ -25,26 +27,35 @@ import ( // the original packet that caused the ICMP one to be sent. This information is // used to find out which transport endpoint must be notified about the ICMP // packet. -func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, vv buffer.VectorisedView) { - h := header.IPv6(vv.First()) +func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, pkt *stack.PacketBuffer) { + h, ok := pkt.Data.PullUp(header.IPv6MinimumSize) + if !ok { + return + } + hdr := header.IPv6(h) // We don't use IsValid() here because ICMP only requires that up to // 1280 bytes of the original packet be included. So it's likely that it // is truncated, which would cause IsValid to return false. // // Drop packet if it doesn't have the basic IPv6 header or if the - // original source address doesn't match the endpoint's address. - if len(h) < header.IPv6MinimumSize || h.SourceAddress() != e.id.LocalAddress { + // original source address doesn't match an address we own. + src := hdr.SourceAddress() + if e.stack.CheckLocalAddress(e.NICID(), ProtocolNumber, src) == 0 { return } // Skip the IP header, then handle the fragmentation header if there // is one. - vv.TrimFront(header.IPv6MinimumSize) - p := h.TransportProtocol() + pkt.Data.TrimFront(header.IPv6MinimumSize) + p := hdr.TransportProtocol() if p == header.IPv6FragmentHeader { - f := header.IPv6Fragment(vv.First()) - if !f.IsValid() || f.FragmentOffset() != 0 { + f, ok := pkt.Data.PullUp(header.IPv6FragmentHeaderSize) + if !ok { + return + } + fragHdr := header.IPv6Fragment(f) + if !fragHdr.IsValid() || fragHdr.FragmentOffset() != 0 { // We can't handle fragments that aren't at offset 0 // because they don't have the transport headers. return @@ -52,145 +63,183 @@ func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, vv buffer. // Skip fragmentation header and find out the actual protocol // number. - vv.TrimFront(header.IPv6FragmentHeaderSize) - p = f.TransportProtocol() + pkt.Data.TrimFront(header.IPv6FragmentHeaderSize) + p = fragHdr.TransportProtocol() } // Deliver the control packet to the transport endpoint. - e.dispatcher.DeliverTransportControlPacket(e.id.LocalAddress, h.DestinationAddress(), ProtocolNumber, p, typ, extra, vv) + e.dispatcher.DeliverTransportControlPacket(src, hdr.DestinationAddress(), ProtocolNumber, p, typ, extra, pkt) } -func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.VectorisedView) { +func (e *endpoint) handleICMP(r *stack.Route, pkt *stack.PacketBuffer, hasFragmentHeader bool) { stats := r.Stats().ICMP sent := stats.V6PacketsSent received := stats.V6PacketsReceived - v := vv.First() - if len(v) < header.ICMPv6MinimumSize { + // TODO(gvisor.dev/issue/170): ICMP packets don't have their + // TransportHeader fields set. See icmp/protocol.go:protocol.Parse for a + // full explanation. + v, ok := pkt.Data.PullUp(header.ICMPv6HeaderSize) + if !ok { received.Invalid.Increment() return } h := header.ICMPv6(v) - iph := header.IPv6(netHeader) + iph := header.IPv6(pkt.NetworkHeader().View()) // Validate ICMPv6 checksum before processing the packet. // - // Only the first view in vv is accounted for by h. To account for the - // rest of vv, a shallow copy is made and the first view is removed. // This copy is used as extra payload during the checksum calculation. - payload := vv - payload.RemoveFirst() + payload := pkt.Data.Clone(nil) + payload.TrimFront(len(h)) if got, want := h.Checksum(), header.ICMPv6Checksum(h, iph.SourceAddress(), iph.DestinationAddress(), payload); got != want { received.Invalid.Increment() return } - // As per RFC 4861 sections 4.1 - 4.5, 6.1.1, 6.1.2, 7.1.1, 7.1.2 and - // 8.1, nodes MUST silently drop NDP packets where the Hop Limit field - // in the IPv6 header is not set to 255. - switch h.Type() { - case header.ICMPv6NeighborSolicit, - header.ICMPv6NeighborAdvert, - header.ICMPv6RouterSolicit, - header.ICMPv6RouterAdvert, - header.ICMPv6RedirectMsg: - if iph.HopLimit() != header.NDPHopLimit { - received.Invalid.Increment() - return - } + isNDPValid := func() bool { + // As per RFC 4861 sections 4.1 - 4.5, 6.1.1, 6.1.2, 7.1.1, 7.1.2 and + // 8.1, nodes MUST silently drop NDP packets where the Hop Limit field + // in the IPv6 header is not set to 255, or the ICMPv6 Code field is not + // set to 0. + // + // As per RFC 6980 section 5, nodes MUST silently drop NDP messages if the + // packet includes a fragmentation header. + return !hasFragmentHeader && iph.HopLimit() == header.NDPHopLimit && h.Code() == 0 } // TODO(b/112892170): Meaningfully handle all ICMP types. switch h.Type() { case header.ICMPv6PacketTooBig: received.PacketTooBig.Increment() - if len(v) < header.ICMPv6PacketTooBigMinimumSize { + hdr, ok := pkt.Data.PullUp(header.ICMPv6PacketTooBigMinimumSize) + if !ok { received.Invalid.Increment() return } - vv.TrimFront(header.ICMPv6PacketTooBigMinimumSize) - mtu := h.MTU() - e.handleControl(stack.ControlPacketTooBig, calculateMTU(mtu), vv) + pkt.Data.TrimFront(header.ICMPv6PacketTooBigMinimumSize) + mtu := header.ICMPv6(hdr).MTU() + e.handleControl(stack.ControlPacketTooBig, calculateMTU(mtu), pkt) case header.ICMPv6DstUnreachable: received.DstUnreachable.Increment() - if len(v) < header.ICMPv6DstUnreachableMinimumSize { + hdr, ok := pkt.Data.PullUp(header.ICMPv6DstUnreachableMinimumSize) + if !ok { received.Invalid.Increment() return } - vv.TrimFront(header.ICMPv6DstUnreachableMinimumSize) - switch h.Code() { + pkt.Data.TrimFront(header.ICMPv6DstUnreachableMinimumSize) + switch header.ICMPv6(hdr).Code() { + case header.ICMPv6NetworkUnreachable: + e.handleControl(stack.ControlNetworkUnreachable, 0, pkt) case header.ICMPv6PortUnreachable: - e.handleControl(stack.ControlPortUnreachable, 0, vv) + e.handleControl(stack.ControlPortUnreachable, 0, pkt) } case header.ICMPv6NeighborSolicit: received.NeighborSolicit.Increment() - if len(v) < header.ICMPv6NeighborSolicitMinimumSize { + if pkt.Data.Size() < header.ICMPv6NeighborSolicitMinimumSize || !isNDPValid() { + received.Invalid.Increment() + return + } + + // The remainder of payload must be only the neighbor solicitation, so + // payload.ToView() always returns the solicitation. Per RFC 6980 section 5, + // NDP messages cannot be fragmented. Also note that in the common case NDP + // datagrams are very small and ToView() will not incur allocations. + ns := header.NDPNeighborSolicit(payload.ToView()) + it, err := ns.Options().Iter(true) + if err != nil { + // If we have a malformed NDP NS option, drop the packet. received.Invalid.Increment() return } - ns := header.NDPNeighborSolicit(h.NDPPayload()) targetAddr := ns.TargetAddress() s := r.Stack() - rxNICID := r.NICID() - - isTentative, err := s.IsAddrTentative(rxNICID, targetAddr) - if err != nil { - // We will only get an error if rxNICID is unrecognized, - // which should not happen. For now short-circuit this - // packet. + if isTentative, err := s.IsAddrTentative(e.nicID, targetAddr); err != nil { + // We will only get an error if the NIC is unrecognized, which should not + // happen. For now, drop this packet. // // TODO(b/141002840): Handle this better? return - } - - if isTentative { - // If the target address is tentative and the source - // of the packet is a unicast (specified) address, then - // the source of the packet is attempting to perform - // address resolution on the target. In this case, the - // solicitation is silently ignored, as per RFC 4862 - // section 5.4.3. + } else if isTentative { + // If the target address is tentative and the source of the packet is a + // unicast (specified) address, then the source of the packet is + // attempting to perform address resolution on the target. In this case, + // the solicitation is silently ignored, as per RFC 4862 section 5.4.3. // - // If the target address is tentative and the source of - // the packet is the unspecified address (::), then we - // know another node is also performing DAD for the - // same address (since targetAddr is tentative for us, - // we know we are also performing DAD on it). In this - // case we let the stack know so it can handle such a - // scenario and do nothing further with the NDP NS. - if iph.SourceAddress() == header.IPv6Any { - s.DupTentativeAddrDetected(rxNICID, targetAddr) + // If the target address is tentative and the source of the packet is the + // unspecified address (::), then we know another node is also performing + // DAD for the same address (since the target address is tentative for us, + // we know we are also performing DAD on it). In this case we let the + // stack know so it can handle such a scenario and do nothing further with + // the NS. + if r.RemoteAddress == header.IPv6Any { + s.DupTentativeAddrDetected(e.nicID, targetAddr) } - // Do not handle neighbor solicitations targeted - // to an address that is tentative on the received - // NIC any further. + // Do not handle neighbor solicitations targeted to an address that is + // tentative on the NIC any further. return } - // At this point we know that targetAddr is not tentative on - // rxNICID so the packet is processed as defined in RFC 4861, - // as per RFC 4862 section 5.4.3. + // At this point we know that the target address is not tentative on the NIC + // so the packet is processed as defined in RFC 4861, as per RFC 4862 + // section 5.4.3. - if e.linkAddrCache.CheckLocalAddress(e.nicid, ProtocolNumber, targetAddr) == 0 { - // We don't have a useful answer; the best we can do is ignore the request. + // Is the NS targetting us? + if e.linkAddrCache.CheckLocalAddress(e.nicID, ProtocolNumber, targetAddr) == 0 { return } - optsSerializer := header.NDPOptionsSerializer{ - header.NDPTargetLinkLayerAddressOption(r.LocalLinkAddress[:]), + // If the NS message contains the Source Link-Layer Address option, update + // the link address cache with the value of the option. + // + // TODO(b/148429853): Properly process the NS message and do Neighbor + // Unreachability Detection. + var sourceLinkAddr tcpip.LinkAddress + for { + opt, done, err := it.Next() + if err != nil { + // This should never happen as Iter(true) above did not return an error. + panic(fmt.Sprintf("unexpected error when iterating over NDP options: %s", err)) + } + if done { + break + } + + switch opt := opt.(type) { + case header.NDPSourceLinkLayerAddressOption: + // No RFCs define what to do when an NS message has multiple Source + // Link-Layer Address options. Since no interface can have multiple + // link-layer addresses, we consider such messages invalid. + if len(sourceLinkAddr) != 0 { + received.Invalid.Increment() + return + } + + sourceLinkAddr = opt.EthernetAddress() + } + } + + unspecifiedSource := r.RemoteAddress == header.IPv6Any + + // As per RFC 4861 section 4.3, the Source Link-Layer Address Option MUST + // NOT be included when the source IP address is the unspecified address. + // Otherwise, on link layers that have addresses this option MUST be + // included in multicast solicitations and SHOULD be included in unicast + // solicitations. + if len(sourceLinkAddr) == 0 { + if header.IsV6MulticastAddress(r.LocalAddress) && !unspecifiedSource { + received.Invalid.Increment() + return + } + } else if unspecifiedSource { + received.Invalid.Increment() + return + } else { + e.linkAddrCache.AddLinkAddress(e.nicID, r.RemoteAddress, sourceLinkAddr) } - hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv6NeighborAdvertMinimumSize + int(optsSerializer.Length())) - pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborAdvertSize)) - pkt.SetType(header.ICMPv6NeighborAdvert) - na := header.NDPNeighborAdvert(pkt.NDPPayload()) - na.SetSolicitedFlag(true) - na.SetOverrideFlag(true) - na.SetTargetAddress(targetAddr) - opts := na.Options() - opts.Serialize(optsSerializer) // ICMPv6 Neighbor Solicit messages are always sent to // specially crafted IPv6 multicast addresses. As a result, the @@ -203,16 +252,43 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V r := r.Clone() defer r.Release() r.LocalAddress = targetAddr - pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{})) - // TODO(tamird/ghanan): there exists an explicit NDP option that is - // used to update the neighbor table with link addresses for a - // neighbor from an NS (see the Source Link Layer option RFC - // 4861 section 4.6.1 and section 7.2.3). + // As per RFC 4861 section 7.2.4, if the the source of the solicitation is + // the unspecified address, the node MUST set the Solicited flag to zero and + // multicast the advertisement to the all-nodes address. + solicited := true + if unspecifiedSource { + solicited = false + r.RemoteAddress = header.IPv6AllNodesMulticastAddress + } + + // If the NS has a source link-layer option, use the link address it + // specifies as the remote link address for the response instead of the + // source link address of the packet. // - // Furthermore, the entirety of NDP handling here seems to be - // contradicted by RFC 4861. - e.linkAddrCache.AddLinkAddress(e.nicid, r.RemoteAddress, r.RemoteLinkAddress) + // TODO(#2401): As per RFC 4861 section 7.2.4 we should consult our link + // address cache for the right destination link address instead of manually + // patching the route with the remote link address if one is specified in a + // Source Link-Layer Address option. + if len(sourceLinkAddr) != 0 { + r.RemoteLinkAddress = sourceLinkAddr + } + + optsSerializer := header.NDPOptionsSerializer{ + header.NDPTargetLinkLayerAddressOption(r.LocalLinkAddress), + } + pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ + ReserveHeaderBytes: int(r.MaxHeaderLength()) + header.ICMPv6NeighborAdvertMinimumSize + int(optsSerializer.Length()), + }) + packet := header.ICMPv6(pkt.TransportHeader().Push(header.ICMPv6NeighborAdvertSize)) + packet.SetType(header.ICMPv6NeighborAdvert) + na := header.NDPNeighborAdvert(packet.NDPPayload()) + na.SetSolicitedFlag(solicited) + na.SetOverrideFlag(true) + na.SetTargetAddress(targetAddr) + opts := na.Options() + opts.Serialize(optsSerializer) + packet.SetChecksum(header.ICMPv6Checksum(packet, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{})) // RFC 4861 Neighbor Discovery for IP version 6 (IPv6) // @@ -220,7 +296,7 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V // // The IP Hop Limit field has a value of 255, i.e., the packet // could not possibly have been forwarded by a router. - if err := r.WritePacket(nil /* gso */, hdr, buffer.VectorisedView{}, stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: header.NDPHopLimit, TOS: stack.DefaultTOS}); err != nil { + if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: header.NDPHopLimit, TOS: stack.DefaultTOS}, pkt); err != nil { sent.Dropped.Increment() return } @@ -228,64 +304,121 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V case header.ICMPv6NeighborAdvert: received.NeighborAdvert.Increment() - if len(v) < header.ICMPv6NeighborAdvertSize { + if pkt.Data.Size() < header.ICMPv6NeighborAdvertSize || !isNDPValid() { + received.Invalid.Increment() + return + } + + // The remainder of payload must be only the neighbor advertisement, so + // payload.ToView() always returns the advertisement. Per RFC 6980 section + // 5, NDP messages cannot be fragmented. Also note that in the common case + // NDP datagrams are very small and ToView() will not incur allocations. + na := header.NDPNeighborAdvert(payload.ToView()) + it, err := na.Options().Iter(true) + if err != nil { + // If we have a malformed NDP NA option, drop the packet. received.Invalid.Increment() return } - na := header.NDPNeighborAdvert(h.NDPPayload()) targetAddr := na.TargetAddress() stack := r.Stack() - rxNICID := r.NICID() - isTentative, err := stack.IsAddrTentative(rxNICID, targetAddr) - if err != nil { - // We will only get an error if rxNICID is unrecognized, - // which should not happen. For now short-circuit this - // packet. + if isTentative, err := stack.IsAddrTentative(e.nicID, targetAddr); err != nil { + // We will only get an error if the NIC is unrecognized, which should not + // happen. For now short-circuit this packet. // // TODO(b/141002840): Handle this better? return - } - - if isTentative { - // We just got an NA from a node that owns an address we - // are performing DAD on, implying the address is not - // unique. In this case we let the stack know so it can - // handle such a scenario and do nothing furthur with + } else if isTentative { + // We just got an NA from a node that owns an address we are performing + // DAD on, implying the address is not unique. In this case we let the + // stack know so it can handle such a scenario and do nothing furthur with // the NDP NA. - stack.DupTentativeAddrDetected(rxNICID, targetAddr) + stack.DupTentativeAddrDetected(e.nicID, targetAddr) return } - // At this point we know that the targetAddress is not tentative - // on rxNICID. However, targetAddr may still be assigned to - // rxNICID but not tentative (it could be permanent). Such a - // scenario is beyond the scope of RFC 4862. As such, we simply - // ignore such a scenario for now and proceed as normal. + // At this point we know that the target address is not tentative on the + // NIC. However, the target address may still be assigned to the NIC but not + // tentative (it could be permanent). Such a scenario is beyond the scope of + // RFC 4862. As such, we simply ignore such a scenario for now and proceed + // as normal. + // + // TODO(b/143147598): Handle the scenario described above. Also inform the + // netstack integration that a duplicate address was detected outside of + // DAD. + + // If the NA message has the target link layer option, update the link + // address cache with the link address for the target of the message. // - // TODO(b/143147598): Handle the scenario described above. Also - // inform the netstack integration that a duplicate address was - // detected outside of DAD. + // TODO(b/148429853): Properly process the NA message and do Neighbor + // Unreachability Detection. + var targetLinkAddr tcpip.LinkAddress + for { + opt, done, err := it.Next() + if err != nil { + // This should never happen as Iter(true) above did not return an error. + panic(fmt.Sprintf("unexpected error when iterating over NDP options: %s", err)) + } + if done { + break + } + + switch opt := opt.(type) { + case header.NDPTargetLinkLayerAddressOption: + // No RFCs define what to do when an NA message has multiple Target + // Link-Layer Address options. Since no interface can have multiple + // link-layer addresses, we consider such messages invalid. + if len(targetLinkAddr) != 0 { + received.Invalid.Increment() + return + } + + targetLinkAddr = opt.EthernetAddress() + } + } - e.linkAddrCache.AddLinkAddress(e.nicid, targetAddr, r.RemoteLinkAddress) - if targetAddr != r.RemoteAddress { - e.linkAddrCache.AddLinkAddress(e.nicid, r.RemoteAddress, r.RemoteLinkAddress) + if len(targetLinkAddr) != 0 { + e.linkAddrCache.AddLinkAddress(e.nicID, targetAddr, targetLinkAddr) } case header.ICMPv6EchoRequest: received.EchoRequest.Increment() - if len(v) < header.ICMPv6EchoMinimumSize { + icmpHdr, ok := pkt.TransportHeader().Consume(header.ICMPv6EchoMinimumSize) + if !ok { received.Invalid.Increment() return } - vv.TrimFront(header.ICMPv6EchoMinimumSize) - hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv6EchoMinimumSize) - pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6EchoMinimumSize)) - copy(pkt, h) - pkt.SetType(header.ICMPv6EchoReply) - pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, vv)) - if err := r.WritePacket(nil /* gso */, hdr, vv, stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: r.DefaultTTL(), TOS: stack.DefaultTOS}); err != nil { + + remoteLinkAddr := r.RemoteLinkAddress + + // As per RFC 4291 section 2.7, multicast addresses must not be used as + // source addresses in IPv6 packets. + localAddr := r.LocalAddress + if header.IsV6MulticastAddress(r.LocalAddress) { + localAddr = "" + } + + r, err := r.Stack().FindRoute(e.NICID(), localAddr, r.RemoteAddress, ProtocolNumber, false /* multicastLoop */) + if err != nil { + // If we cannot find a route to the destination, silently drop the packet. + return + } + defer r.Release() + + // Use the link address from the source of the original packet. + r.ResolveWith(remoteLinkAddr) + + replyPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ + ReserveHeaderBytes: int(r.MaxHeaderLength()) + header.ICMPv6EchoMinimumSize, + Data: pkt.Data, + }) + packet := header.ICMPv6(replyPkt.TransportHeader().Push(header.ICMPv6EchoMinimumSize)) + copy(packet, icmpHdr) + packet.SetType(header.ICMPv6EchoReply) + packet.SetChecksum(header.ICMPv6Checksum(packet, r.LocalAddress, r.RemoteAddress, pkt.Data)) + if err := r.WritePacket(nil /* gso */, stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: r.DefaultTTL(), TOS: stack.DefaultTOS}, replyPkt); err != nil { sent.Dropped.Increment() return } @@ -293,11 +426,11 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V case header.ICMPv6EchoReply: received.EchoReply.Increment() - if len(v) < header.ICMPv6EchoMinimumSize { + if pkt.Data.Size() < header.ICMPv6EchoMinimumSize { received.Invalid.Increment() return } - e.dispatcher.DeliverTransportPacket(r, header.ICMPv6ProtocolNumber, netHeader, vv) + e.dispatcher.DeliverTransportPacket(r, header.ICMPv6ProtocolNumber, pkt) case header.ICMPv6TimeExceeded: received.TimeExceeded.Increment() @@ -307,12 +440,64 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V case header.ICMPv6RouterSolicit: received.RouterSolicit.Increment() + if !isNDPValid() { + received.Invalid.Increment() + return + } case header.ICMPv6RouterAdvert: received.RouterAdvert.Increment() + // Is the NDP payload of sufficient size to hold a Router + // Advertisement? + if pkt.Data.Size()-header.ICMPv6HeaderSize < header.NDPRAMinimumSize || !isNDPValid() { + received.Invalid.Increment() + return + } + + routerAddr := iph.SourceAddress() + + // + // Validate the RA as per RFC 4861 section 6.1.2. + // + + // Is the IP Source Address a link-local address? + if !header.IsV6LinkLocalAddress(routerAddr) { + // ...No, silently drop the packet. + received.Invalid.Increment() + return + } + + // The remainder of payload must be only the router advertisement, so + // payload.ToView() always returns the advertisement. Per RFC 6980 section + // 5, NDP messages cannot be fragmented. Also note that in the common case + // NDP datagrams are very small and ToView() will not incur allocations. + ra := header.NDPRouterAdvert(payload.ToView()) + opts := ra.Options() + + // Are options valid as per the wire format? + if _, err := opts.Iter(true); err != nil { + // ...No, silently drop the packet. + received.Invalid.Increment() + return + } + + // + // At this point, we have a valid Router Advertisement, as far + // as RFC 4861 section 6.1.2 is concerned. + // + + // Tell the NIC to handle the RA. + stack := r.Stack() + rxNICID := r.NICID() + stack.HandleNDPRA(rxNICID, routerAddr, ra) + case header.ICMPv6RedirectMsg: received.RedirectMsg.Increment() + if !isNDPValid() { + received.Invalid.Increment() + return + } default: received.Invalid.Increment() @@ -331,8 +516,6 @@ const ( icmpV6LengthOffset = 25 ) -var broadcastMAC = tcpip.LinkAddress([]byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}) - var _ stack.LinkAddressResolver = (*protocol)(nil) // LinkAddressProtocol implements stack.LinkAddressResolver. @@ -341,24 +524,34 @@ func (*protocol) LinkAddressProtocol() tcpip.NetworkProtocolNumber { } // LinkAddressRequest implements stack.LinkAddressResolver. -func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, linkEP stack.LinkEndpoint) *tcpip.Error { +func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, remoteLinkAddr tcpip.LinkAddress, linkEP stack.LinkEndpoint) *tcpip.Error { snaddr := header.SolicitedNodeAddr(addr) + + // TODO(b/148672031): Use stack.FindRoute instead of manually creating the + // route here. Note, we would need the nicID to do this properly so the right + // NIC (associated to linkEP) is used to send the NDP NS message. r := &stack.Route{ LocalAddress: localAddr, RemoteAddress: snaddr, - RemoteLinkAddress: broadcastMAC, + RemoteLinkAddress: remoteLinkAddr, + } + if len(r.RemoteLinkAddress) == 0 { + r.RemoteLinkAddress = header.EthernetAddressFromMulticastIPv6Address(snaddr) } - hdr := buffer.NewPrependable(int(linkEP.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6NeighborAdvertSize) - pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborAdvertSize)) - pkt.SetType(header.ICMPv6NeighborSolicit) - copy(pkt[icmpV6OptOffset-len(addr):], addr) - pkt[icmpV6OptOffset] = ndpOptSrcLinkAddr - pkt[icmpV6LengthOffset] = 1 - copy(pkt[icmpV6LengthOffset+1:], linkEP.LinkAddress()) - pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{})) - - length := uint16(hdr.UsedLength()) - ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize)) + + pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{ + ReserveHeaderBytes: int(linkEP.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6NeighborAdvertSize, + }) + icmpHdr := header.ICMPv6(pkt.TransportHeader().Push(header.ICMPv6NeighborAdvertSize)) + icmpHdr.SetType(header.ICMPv6NeighborSolicit) + copy(icmpHdr[icmpV6OptOffset-len(addr):], addr) + icmpHdr[icmpV6OptOffset] = ndpOptSrcLinkAddr + icmpHdr[icmpV6LengthOffset] = 1 + copy(icmpHdr[icmpV6LengthOffset+1:], linkEP.LinkAddress()) + icmpHdr.SetChecksum(header.ICMPv6Checksum(icmpHdr, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{})) + + length := uint16(pkt.Size()) + ip := header.IPv6(pkt.NetworkHeader().Push(header.IPv6MinimumSize)) ip.Encode(&header.IPv6Fields{ PayloadLength: length, NextHeader: uint8(header.ICMPv6ProtocolNumber), @@ -368,29 +561,13 @@ func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, linkEP stack. }) // TODO(stijlist): count this in ICMP stats. - return linkEP.WritePacket(r, nil /* gso */, hdr, buffer.VectorisedView{}, ProtocolNumber) + return linkEP.WritePacket(r, nil /* gso */, ProtocolNumber, pkt) } // ResolveStaticAddress implements stack.LinkAddressResolver. func (*protocol) ResolveStaticAddress(addr tcpip.Address) (tcpip.LinkAddress, bool) { if header.IsV6MulticastAddress(addr) { - // RFC 2464 Transmission of IPv6 Packets over Ethernet Networks - // - // 7. Address Mapping -- Multicast - // - // An IPv6 packet with a multicast destination address DST, - // consisting of the sixteen octets DST[1] through DST[16], is - // transmitted to the Ethernet multicast address whose first - // two octets are the value 3333 hexadecimal and whose last - // four octets are the last four octets of DST. - return tcpip.LinkAddress([]byte{ - 0x33, - 0x33, - addr[header.IPv6AddressSize-4], - addr[header.IPv6AddressSize-3], - addr[header.IPv6AddressSize-2], - addr[header.IPv6AddressSize-1], - }), true + return header.EthernetAddressFromMulticastIPv6Address(addr), true } - return "", false + return tcpip.LinkAddress([]byte(nil)), false } |