318 lines
14 KiB
Go
318 lines
14 KiB
Go
// Copyright 2019 the Kilo authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//go:build linux
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// +build linux
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package mesh
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import (
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"net"
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"github.com/vishvananda/netlink"
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"golang.org/x/sys/unix"
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"github.com/squat/kilo/pkg/encapsulation"
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"github.com/squat/kilo/pkg/iptables"
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)
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const kiloTableIndex = 1107
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// Routes generates a slice of routes for a given Topology.
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func (t *Topology) Routes(kiloIfaceName string, kiloIface, privIface, tunlIface int, local bool, enc encapsulation.Encapsulator) ([]*netlink.Route, []*netlink.Rule) {
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var routes []*netlink.Route
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var rules []*netlink.Rule
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if !t.leader {
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// Find the GW for this segment.
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// This will be the an IP of the leader.
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// In an IPIP encapsulated mesh it is the leader's private IP.
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var gw net.IP
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for _, segment := range t.segments {
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if segment.location == t.location {
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gw = enc.Gw(segment.endpoint.IP, segment.privateIPs[segment.leader], segment.cidrs[segment.leader])
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break
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}
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}
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for _, segment := range t.segments {
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// First, add a route to the WireGuard IP of the segment.
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routes = append(routes, encapsulateRoute(&netlink.Route{
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Dst: oneAddressCIDR(segment.wireGuardIP),
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Flags: int(netlink.FLAG_ONLINK),
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Gw: gw,
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LinkIndex: privIface,
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Protocol: unix.RTPROT_STATIC,
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}, enc.Strategy(), t.privateIP, tunlIface))
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// Add routes for the current segment if local is true.
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if segment.location == t.location {
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if local {
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for i := range segment.cidrs {
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// Don't add routes for the local node.
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if segment.privateIPs[i].Equal(t.privateIP.IP) {
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continue
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}
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routes = append(routes, encapsulateRoute(&netlink.Route{
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Dst: segment.cidrs[i],
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Flags: int(netlink.FLAG_ONLINK),
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Gw: segment.privateIPs[i],
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LinkIndex: privIface,
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Protocol: unix.RTPROT_STATIC,
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}, enc.Strategy(), t.privateIP, tunlIface))
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// Encapsulate packets from the host's Pod subnet headed
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// to private IPs.
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if enc.Strategy() == encapsulation.Always || (enc.Strategy() == encapsulation.CrossSubnet && !t.privateIP.Contains(segment.privateIPs[i])) {
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routes = append(routes, &netlink.Route{
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Dst: oneAddressCIDR(segment.privateIPs[i]),
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Flags: int(netlink.FLAG_ONLINK),
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Gw: segment.privateIPs[i],
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LinkIndex: tunlIface,
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Protocol: unix.RTPROT_STATIC,
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Table: kiloTableIndex,
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})
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rules = append(rules, defaultRule(&netlink.Rule{
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Src: t.subnet,
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Dst: oneAddressCIDR(segment.privateIPs[i]),
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Table: kiloTableIndex,
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}))
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}
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}
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}
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continue
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}
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for i := range segment.cidrs {
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// Add routes to the Pod CIDRs of nodes in other segments.
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routes = append(routes, encapsulateRoute(&netlink.Route{
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Dst: segment.cidrs[i],
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Flags: int(netlink.FLAG_ONLINK),
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Gw: gw,
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LinkIndex: privIface,
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Protocol: unix.RTPROT_STATIC,
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}, enc.Strategy(), t.privateIP, tunlIface))
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}
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for i := range segment.privateIPs {
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// Add routes to the private IPs of nodes in other segments.
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routes = append(routes, encapsulateRoute(&netlink.Route{
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Dst: oneAddressCIDR(segment.privateIPs[i]),
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Flags: int(netlink.FLAG_ONLINK),
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Gw: gw,
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LinkIndex: privIface,
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Protocol: unix.RTPROT_STATIC,
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}, enc.Strategy(), t.privateIP, tunlIface))
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}
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// For segments / locations other than the location of this instance of kg,
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// we need to set routes for allowed location IPs over the leader in the current location.
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for i := range segment.allowedLocationIPs {
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routes = append(routes, encapsulateRoute(&netlink.Route{
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Dst: segment.allowedLocationIPs[i],
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Flags: int(netlink.FLAG_ONLINK),
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Gw: gw,
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LinkIndex: privIface,
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Protocol: unix.RTPROT_STATIC,
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}, enc.Strategy(), t.privateIP, tunlIface))
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}
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}
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// Add routes for the allowed IPs of peers.
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for _, peer := range t.peers {
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for i := range peer.AllowedIPs {
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routes = append(routes, encapsulateRoute(&netlink.Route{
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Dst: peer.AllowedIPs[i],
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Flags: int(netlink.FLAG_ONLINK),
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Gw: gw,
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LinkIndex: privIface,
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Protocol: unix.RTPROT_STATIC,
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}, enc.Strategy(), t.privateIP, tunlIface))
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}
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}
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return routes, rules
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}
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for _, segment := range t.segments {
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// Add routes for the current segment if local is true.
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if segment.location == t.location {
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// If the local node does not have a private IP address,
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// then skip adding routes, because the node is in its own location.
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if local && t.privateIP != nil {
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for i := range segment.cidrs {
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// Don't add routes for the local node.
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if segment.privateIPs[i].Equal(t.privateIP.IP) {
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continue
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}
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routes = append(routes, encapsulateRoute(&netlink.Route{
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Dst: segment.cidrs[i],
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Flags: int(netlink.FLAG_ONLINK),
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Gw: segment.privateIPs[i],
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LinkIndex: privIface,
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Protocol: unix.RTPROT_STATIC,
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}, enc.Strategy(), t.privateIP, tunlIface))
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// Encapsulate packets from the host's Pod subnet headed
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// to private IPs.
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if enc.Strategy() == encapsulation.Always || (enc.Strategy() == encapsulation.CrossSubnet && !t.privateIP.Contains(segment.privateIPs[i])) {
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routes = append(routes, &netlink.Route{
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Dst: oneAddressCIDR(segment.privateIPs[i]),
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Flags: int(netlink.FLAG_ONLINK),
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Gw: segment.privateIPs[i],
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LinkIndex: tunlIface,
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Protocol: unix.RTPROT_STATIC,
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Table: kiloTableIndex,
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})
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rules = append(rules, defaultRule(&netlink.Rule{
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Src: t.subnet,
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Dst: oneAddressCIDR(segment.privateIPs[i]),
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Table: kiloTableIndex,
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}))
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// Also encapsulate packets from the Kilo interface
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// headed to private IPs.
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rules = append(rules, defaultRule(&netlink.Rule{
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Dst: oneAddressCIDR(segment.privateIPs[i]),
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Table: kiloTableIndex,
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IifName: kiloIfaceName,
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}))
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}
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}
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}
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// Continuing here prevents leaders form adding routes via WireGuard to
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// nodes in their own location.
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continue
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}
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for i := range segment.cidrs {
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// Add routes to the Pod CIDRs of nodes in other segments.
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routes = append(routes, &netlink.Route{
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Dst: segment.cidrs[i],
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Flags: int(netlink.FLAG_ONLINK),
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Gw: segment.wireGuardIP,
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LinkIndex: kiloIface,
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Protocol: unix.RTPROT_STATIC,
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})
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// Don't add routes through Kilo if the private IP
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// equals the external IP. This means that the node
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// is only accessible through an external IP and we
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// cannot encapsulate traffic to an IP through the IP.
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if segment.privateIPs == nil || segment.privateIPs[i].Equal(segment.endpoint.IP) {
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continue
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}
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// Add routes to the private IPs of nodes in other segments.
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// Number of CIDRs and private IPs always match so
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// we can reuse the loop.
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routes = append(routes, &netlink.Route{
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Dst: oneAddressCIDR(segment.privateIPs[i]),
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Flags: int(netlink.FLAG_ONLINK),
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Gw: segment.wireGuardIP,
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LinkIndex: kiloIface,
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Protocol: unix.RTPROT_STATIC,
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})
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}
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// For segments / locations other than the location of this instance of kg,
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// we need to set routes for allowed location IPs over the wg interface.
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for i := range segment.allowedLocationIPs {
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routes = append(routes, &netlink.Route{
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Dst: segment.allowedLocationIPs[i],
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Flags: int(netlink.FLAG_ONLINK),
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Gw: segment.wireGuardIP,
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LinkIndex: kiloIface,
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Protocol: unix.RTPROT_STATIC,
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})
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}
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}
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// Add routes for the allowed IPs of peers.
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for _, peer := range t.peers {
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for i := range peer.AllowedIPs {
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routes = append(routes, &netlink.Route{
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Dst: peer.AllowedIPs[i],
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LinkIndex: kiloIface,
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Protocol: unix.RTPROT_STATIC,
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})
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}
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}
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return routes, rules
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}
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func encapsulateRoute(route *netlink.Route, encapsulate encapsulation.Strategy, subnet *net.IPNet, tunlIface int) *netlink.Route {
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if encapsulate == encapsulation.Always || (encapsulate == encapsulation.CrossSubnet && !subnet.Contains(route.Gw)) {
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route.LinkIndex = tunlIface
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}
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return route
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}
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// Rules returns the iptables rules required by the local node.
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func (t *Topology) Rules(cni, iptablesForwardRule bool) []iptables.Rule {
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var rules []iptables.Rule
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rules = append(rules, iptables.NewIPv4Chain("nat", "KILO-NAT"))
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rules = append(rules, iptables.NewIPv6Chain("nat", "KILO-NAT"))
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if cni {
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(t.subnet.IP)), "nat", "POSTROUTING", "-s", t.subnet.String(), "-m", "comment", "--comment", "Kilo: jump to KILO-NAT chain", "-j", "KILO-NAT"))
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// Some linux distros or docker will set forward DROP in the filter table.
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// To still be able to have pod to pod communication we need to ALLOW packets from and to pod CIDRs within a location.
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// Leader nodes will forward packets from all nodes within a location because they act as a gateway for them.
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// Non leader nodes only need to allow packages from and to their own pod CIDR.
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if iptablesForwardRule && t.leader {
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for _, s := range t.segments {
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if s.location == t.location {
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// Make sure packets to and from pod cidrs are not dropped in the forward chain.
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for _, c := range s.cidrs {
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(c.IP)), "filter", "FORWARD", "-m", "comment", "--comment", "Kilo: forward packets from the pod subnet", "-s", c.String(), "-j", "ACCEPT"))
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(c.IP)), "filter", "FORWARD", "-m", "comment", "--comment", "Kilo: forward packets to the pod subnet", "-d", c.String(), "-j", "ACCEPT"))
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}
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// Make sure packets to and from allowed location IPs are not dropped in the forward chain.
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for _, c := range s.allowedLocationIPs {
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(c.IP)), "filter", "FORWARD", "-m", "comment", "--comment", "Kilo: forward packets from allowed location IPs", "-s", c.String(), "-j", "ACCEPT"))
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(c.IP)), "filter", "FORWARD", "-m", "comment", "--comment", "Kilo: forward packets to allowed location IPs", "-d", c.String(), "-j", "ACCEPT"))
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}
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// Make sure packets to and from private IPs are not dropped in the forward chain.
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for _, c := range s.privateIPs {
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(c)), "filter", "FORWARD", "-m", "comment", "--comment", "Kilo: forward packets from private IPs", "-s", oneAddressCIDR(c).String(), "-j", "ACCEPT"))
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(c)), "filter", "FORWARD", "-m", "comment", "--comment", "Kilo: forward packets to private IPs", "-d", oneAddressCIDR(c).String(), "-j", "ACCEPT"))
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}
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}
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}
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} else if iptablesForwardRule {
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(t.subnet.IP)), "filter", "FORWARD", "-m", "comment", "--comment", "Kilo: forward packets from the node's pod subnet", "-s", t.subnet.String(), "-j", "ACCEPT"))
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(t.subnet.IP)), "filter", "FORWARD", "-m", "comment", "--comment", "Kilo: forward packets to the node's pod subnet", "-d", t.subnet.String(), "-j", "ACCEPT"))
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}
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}
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for _, s := range t.segments {
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(s.wireGuardIP)), "nat", "KILO-NAT", "-d", oneAddressCIDR(s.wireGuardIP).String(), "-m", "comment", "--comment", "Kilo: do not NAT packets destined for WireGuared IPs", "-j", "RETURN"))
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for _, aip := range s.allowedIPs {
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rules = append(rules, iptables.NewRule(iptables.GetProtocol(len(aip.IP)), "nat", "KILO-NAT", "-d", aip.String(), "-m", "comment", "--comment", "Kilo: do not NAT packets destined for known IPs", "-j", "RETURN"))
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}
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// Make sure packets to allowed location IPs go through the KILO-NAT chain, so they can be MASQUERADEd,
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// Otherwise packets to these destinations will reach the destination, but never find their way back.
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// We only want to NAT in locations of the corresponding allowed location IPs.
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if t.location == s.location {
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for _, alip := range s.allowedLocationIPs {
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rules = append(rules,
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iptables.NewRule(iptables.GetProtocol(len(alip.IP)), "nat", "POSTROUTING", "-d", alip.String(), "-m", "comment", "--comment", "Kilo: jump to NAT chain", "-j", "KILO-NAT"),
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)
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}
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}
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}
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for _, p := range t.peers {
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for _, aip := range p.AllowedIPs {
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rules = append(rules,
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iptables.NewRule(iptables.GetProtocol(len(aip.IP)), "nat", "POSTROUTING", "-s", aip.String(), "-m", "comment", "--comment", "Kilo: jump to NAT chain", "-j", "KILO-NAT"),
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iptables.NewRule(iptables.GetProtocol(len(aip.IP)), "nat", "KILO-NAT", "-d", aip.String(), "-m", "comment", "--comment", "Kilo: do not NAT packets destined for peers", "-j", "RETURN"),
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)
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}
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}
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rules = append(rules, iptables.NewIPv4Rule("nat", "KILO-NAT", "-m", "comment", "--comment", "Kilo: NAT remaining packets", "-j", "MASQUERADE"))
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rules = append(rules, iptables.NewIPv6Rule("nat", "KILO-NAT", "-m", "comment", "--comment", "Kilo: NAT remaining packets", "-j", "MASQUERADE"))
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return rules
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}
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func defaultRule(rule *netlink.Rule) *netlink.Rule {
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base := netlink.NewRule()
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base.Src = rule.Src
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base.Dst = rule.Dst
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base.IifName = rule.IifName
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base.Table = rule.Table
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return base
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}
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