diff options
Diffstat (limited to 'pkg/tcpip/network/ipv6/icmp.go')
| -rw-r--r-- | pkg/tcpip/network/ipv6/icmp.go | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go index 8b8539def..e3ef89d26 100644 --- a/pkg/tcpip/network/ipv6/icmp.go +++ b/pkg/tcpip/network/ipv6/icmp.go @@ -17,6 +17,7 @@ package ipv6 import ( "encoding/binary" + "gvisor.googlesource.com/gvisor/pkg/tcpip" "gvisor.googlesource.com/gvisor/pkg/tcpip/buffer" "gvisor.googlesource.com/gvisor/pkg/tcpip/header" "gvisor.googlesource.com/gvisor/pkg/tcpip/stack" @@ -86,5 +87,139 @@ func (e *endpoint) handleICMP(r *stack.Route, vv *buffer.VectorisedView) { case header.ICMPv6PortUnreachable: e.handleControl(stack.ControlPortUnreachable, 0, vv) } + + case header.ICMPv6NeighborSolicit: + if len(v) < header.ICMPv6NeighborSolicitMinimumSize { + return + } + targetAddr := tcpip.Address(v[8 : 8+16]) + 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. + return + } + hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6NeighborAdvertSize) + pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborAdvertSize)) + pkt.SetType(header.ICMPv6NeighborAdvert) + pkt[icmpV6FlagOffset] = ndpSolicitedFlag | ndpOverrideFlag + copy(pkt[icmpV6OptOffset-len(targetAddr):], targetAddr) + pkt[icmpV6OptOffset] = ndpOptDstLinkAddr + pkt[icmpV6LengthOffset] = 1 + copy(pkt[icmpV6LengthOffset+1:], r.LocalLinkAddress[:]) + pkt.SetChecksum(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, nil)) + r.WritePacket(&hdr, nil, header.ICMPv6ProtocolNumber) + + e.linkAddrCache.AddLinkAddress(e.nicid, r.RemoteAddress, r.RemoteLinkAddress) + + case header.ICMPv6NeighborAdvert: + if len(v) < header.ICMPv6NeighborAdvertSize { + return + } + targetAddr := tcpip.Address(v[8 : 8+16]) + e.linkAddrCache.AddLinkAddress(e.nicid, targetAddr, r.RemoteLinkAddress) + if targetAddr != r.RemoteAddress { + e.linkAddrCache.AddLinkAddress(e.nicid, r.RemoteAddress, r.RemoteLinkAddress) + } + + case header.ICMPv6EchoRequest: + if len(v) < header.ICMPv6EchoMinimumSize { + return + } + vv.TrimFront(header.ICMPv6EchoMinimumSize) + data := vv.ToView() + hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6EchoMinimumSize) + pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6EchoMinimumSize)) + copy(pkt, h) + pkt.SetType(header.ICMPv6EchoReply) + pkt.SetChecksum(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, data)) + r.WritePacket(&hdr, data, header.ICMPv6ProtocolNumber) + + case header.ICMPv6EchoReply: + if len(v) < header.ICMPv6EchoMinimumSize { + return + } + e.dispatcher.DeliverTransportPacket(r, header.ICMPv6ProtocolNumber, vv) + + } +} + +const ( + ndpSolicitedFlag = 1 << 6 + ndpOverrideFlag = 1 << 5 + + ndpOptSrcLinkAddr = 1 + ndpOptDstLinkAddr = 2 + + icmpV6FlagOffset = 4 + icmpV6OptOffset = 24 + icmpV6LengthOffset = 25 +) + +// solicitedNodeAddr computes the solicited-node multicast address. +// This is used for NDP. Described in RFC 4291. +func solicitedNodeAddr(addr tcpip.Address) tcpip.Address { + const solicitedNodeMulticastPrefix = "\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\xff" + return solicitedNodeMulticastPrefix + addr[len(addr)-3:] +} + +var broadcastMAC = tcpip.LinkAddress([]byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}) + +var _ stack.LinkAddressResolver = (*protocol)(nil) + +// LinkAddressProtocol implements stack.LinkAddressResolver. +func (*protocol) LinkAddressProtocol() tcpip.NetworkProtocolNumber { + return header.IPv6ProtocolNumber +} + +// LinkAddressRequest implements stack.LinkAddressResolver. +func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, linkEP stack.LinkEndpoint) *tcpip.Error { + snaddr := solicitedNodeAddr(addr) + r := &stack.Route{ + LocalAddress: localAddr, + RemoteAddress: snaddr, + RemoteLinkAddress: broadcastMAC, } + 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(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, nil)) + + length := uint16(hdr.UsedLength()) + ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize)) + ip.Encode(&header.IPv6Fields{ + PayloadLength: length, + NextHeader: uint8(header.ICMPv6ProtocolNumber), + HopLimit: defaultIPv6HopLimit, + SrcAddr: r.LocalAddress, + DstAddr: r.RemoteAddress, + }) + + return linkEP.WritePacket(r, &hdr, nil, ProtocolNumber) +} + +// ResolveStaticAddress implements stack.LinkAddressResolver. +func (*protocol) ResolveStaticAddress(addr tcpip.Address) (tcpip.LinkAddress, bool) { + return "", false +} + +func icmpChecksum(h header.ICMPv6, src, dst tcpip.Address, data []byte) uint16 { + // Calculate the IPv6 pseudo-header upper-layer checksum. + xsum := header.Checksum([]byte(src), 0) + xsum = header.Checksum([]byte(dst), xsum) + var upperLayerLength [4]byte + binary.BigEndian.PutUint32(upperLayerLength[:], uint32(len(h)+len(data))) + xsum = header.Checksum(upperLayerLength[:], xsum) + xsum = header.Checksum([]byte{0, 0, 0, uint8(header.ICMPv6ProtocolNumber)}, xsum) + xsum = header.Checksum(data, xsum) + + // h[2:4] is the checksum itself, set it aside to avoid checksumming the checksum. + h2, h3 := h[2], h[3] + h[2], h[3] = 0, 0 + xsum = ^header.Checksum(h, xsum) + h[2], h[3] = h2, h3 + + return xsum } |