diff options
Diffstat (limited to 'pkg/tcpip/stack/iptables_targets.go')
| -rw-r--r-- | pkg/tcpip/stack/iptables_targets.go | 97 |
1 files changed, 61 insertions, 36 deletions
diff --git a/pkg/tcpip/stack/iptables_targets.go b/pkg/tcpip/stack/iptables_targets.go index 91e266de8..96cc899bb 100644 --- a/pkg/tcpip/stack/iptables_targets.go +++ b/pkg/tcpip/stack/iptables_targets.go @@ -133,29 +133,23 @@ func (rt *RedirectTarget) Action(pkt *PacketBuffer, ct *ConnTrack, hook Hook, r switch protocol := pkt.TransportProtocolNumber; protocol { case header.UDPProtocolNumber: udpHeader := header.UDP(pkt.TransportHeader().View()) - udpHeader.SetDestinationPort(rt.Port) - // Calculate UDP checksum and set it. if hook == Output { - udpHeader.SetChecksum(0) - netHeader := pkt.Network() - netHeader.SetDestinationAddress(address) - // Only calculate the checksum if offloading isn't supported. - if r.RequiresTXTransportChecksum() { - length := uint16(pkt.Size()) - uint16(len(pkt.NetworkHeader().View())) - xsum := header.PseudoHeaderChecksum(protocol, netHeader.SourceAddress(), netHeader.DestinationAddress(), length) - xsum = header.ChecksumCombine(xsum, pkt.Data().AsRange().Checksum()) - udpHeader.SetChecksum(^udpHeader.CalculateChecksum(xsum)) - } + requiresChecksum := r.RequiresTXTransportChecksum() + rewritePacket( + pkt.Network(), + udpHeader, + false, /* updateSRCFields */ + requiresChecksum, + requiresChecksum, + rt.Port, + address, + ) + } else { + udpHeader.SetDestinationPort(rt.Port) } - // After modification, IPv4 packets need a valid checksum. - if pkt.NetworkProtocolNumber == header.IPv4ProtocolNumber { - netHeader := header.IPv4(pkt.NetworkHeader().View()) - netHeader.SetChecksum(0) - netHeader.SetChecksum(^netHeader.CalculateChecksum()) - } pkt.NatDone = true case header.TCPProtocolNumber: if ct == nil { @@ -214,26 +208,18 @@ func (st *SNATTarget) Action(pkt *PacketBuffer, ct *ConnTrack, hook Hook, r *Rou switch protocol := pkt.TransportProtocolNumber; protocol { case header.UDPProtocolNumber: - udpHeader := header.UDP(pkt.TransportHeader().View()) - udpHeader.SetChecksum(0) - udpHeader.SetSourcePort(st.Port) - netHeader := pkt.Network() - netHeader.SetSourceAddress(st.Addr) - // Only calculate the checksum if offloading isn't supported. - if r.RequiresTXTransportChecksum() { - length := uint16(pkt.Size()) - uint16(len(pkt.NetworkHeader().View())) - xsum := header.PseudoHeaderChecksum(protocol, netHeader.SourceAddress(), netHeader.DestinationAddress(), length) - xsum = header.ChecksumCombine(xsum, pkt.Data().AsRange().Checksum()) - udpHeader.SetChecksum(^udpHeader.CalculateChecksum(xsum)) - } + requiresChecksum := r.RequiresTXTransportChecksum() + rewritePacket( + pkt.Network(), + header.UDP(pkt.TransportHeader().View()), + true, /* updateSRCFields */ + requiresChecksum, + requiresChecksum, + st.Port, + st.Addr, + ) - // After modification, IPv4 packets need a valid checksum. - if pkt.NetworkProtocolNumber == header.IPv4ProtocolNumber { - netHeader := header.IPv4(pkt.NetworkHeader().View()) - netHeader.SetChecksum(0) - netHeader.SetChecksum(^netHeader.CalculateChecksum()) - } pkt.NatDone = true case header.TCPProtocolNumber: if ct == nil { @@ -252,3 +238,42 @@ func (st *SNATTarget) Action(pkt *PacketBuffer, ct *ConnTrack, hook Hook, r *Rou return RuleAccept, 0 } + +func rewritePacket(n header.Network, t header.ChecksummableTransport, updateSRCFields, fullChecksum, updatePseudoHeader bool, newPort uint16, newAddr tcpip.Address) { + if updateSRCFields { + if fullChecksum { + t.SetSourcePortWithChecksumUpdate(newPort) + } else { + t.SetSourcePort(newPort) + } + } else { + if fullChecksum { + t.SetDestinationPortWithChecksumUpdate(newPort) + } else { + t.SetDestinationPort(newPort) + } + } + + if updatePseudoHeader { + var oldAddr tcpip.Address + if updateSRCFields { + oldAddr = n.SourceAddress() + } else { + oldAddr = n.DestinationAddress() + } + + t.UpdateChecksumPseudoHeaderAddress(oldAddr, newAddr, fullChecksum) + } + + if checksummableNetHeader, ok := n.(header.ChecksummableNetwork); ok { + if updateSRCFields { + checksummableNetHeader.SetSourceAddressWithChecksumUpdate(newAddr) + } else { + checksummableNetHeader.SetDestinationAddressWithChecksumUpdate(newAddr) + } + } else if updateSRCFields { + n.SetSourceAddress(newAddr) + } else { + n.SetDestinationAddress(newAddr) + } +} |