mirror of
https://github.com/k3s-io/kubernetes.git
synced 2025-07-27 13:37:30 +00:00
217 lines
8.8 KiB
Go
217 lines
8.8 KiB
Go
//go:build linux
|
|
// +build linux
|
|
|
|
/*
|
|
Copyright 2018 The Kubernetes Authors.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
package kubelet
|
|
|
|
import (
|
|
"fmt"
|
|
"time"
|
|
|
|
"k8s.io/apimachinery/pkg/util/wait"
|
|
utilfeature "k8s.io/apiserver/pkg/util/feature"
|
|
"k8s.io/klog/v2"
|
|
"k8s.io/kubernetes/pkg/features"
|
|
utiliptables "k8s.io/kubernetes/pkg/util/iptables"
|
|
utilexec "k8s.io/utils/exec"
|
|
)
|
|
|
|
const (
|
|
// KubeIPTablesHintChain is the chain whose existence in either iptables-legacy
|
|
// or iptables-nft indicates which version of iptables the system is using
|
|
KubeIPTablesHintChain utiliptables.Chain = "KUBE-IPTABLES-HINT"
|
|
|
|
// KubeMarkMasqChain is the mark-for-masquerade chain
|
|
// TODO: clean up this logic in kube-proxy
|
|
KubeMarkMasqChain utiliptables.Chain = "KUBE-MARK-MASQ"
|
|
|
|
// KubeMarkDropChain is the mark-for-drop chain
|
|
KubeMarkDropChain utiliptables.Chain = "KUBE-MARK-DROP"
|
|
|
|
// KubePostroutingChain is kubernetes postrouting rules
|
|
KubePostroutingChain utiliptables.Chain = "KUBE-POSTROUTING"
|
|
|
|
// KubeFirewallChain is kubernetes firewall rules
|
|
KubeFirewallChain utiliptables.Chain = "KUBE-FIREWALL"
|
|
)
|
|
|
|
func (kl *Kubelet) initNetworkUtil() {
|
|
exec := utilexec.New()
|
|
iptClients := []utiliptables.Interface{
|
|
utiliptables.New(exec, utiliptables.ProtocolIPv4),
|
|
utiliptables.New(exec, utiliptables.ProtocolIPv6),
|
|
}
|
|
|
|
for i := range iptClients {
|
|
iptClient := iptClients[i]
|
|
if kl.syncIPTablesRules(iptClient) {
|
|
klog.InfoS("Initialized iptables rules.", "protocol", iptClient.Protocol())
|
|
go iptClient.Monitor(
|
|
utiliptables.Chain("KUBE-KUBELET-CANARY"),
|
|
[]utiliptables.Table{utiliptables.TableMangle, utiliptables.TableNAT, utiliptables.TableFilter},
|
|
func() { kl.syncIPTablesRules(iptClient) },
|
|
1*time.Minute, wait.NeverStop,
|
|
)
|
|
} else {
|
|
klog.InfoS("Failed to initialize iptables rules; some functionality may be missing.", "protocol", iptClient.Protocol())
|
|
}
|
|
}
|
|
}
|
|
|
|
// syncIPTablesRules ensures the KUBE-IPTABLES-HINT chain exists, and the martian packet
|
|
// protection rule is installed. If the IPTablesOwnershipCleanup feature gate is disabled
|
|
// it will also synchronize additional deprecated iptables rules.
|
|
func (kl *Kubelet) syncIPTablesRules(iptClient utiliptables.Interface) bool {
|
|
// Create hint chain so other components can see whether we are using iptables-legacy
|
|
// or iptables-nft.
|
|
if _, err := iptClient.EnsureChain(utiliptables.TableMangle, KubeIPTablesHintChain); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that iptables hint chain exists")
|
|
return false
|
|
}
|
|
|
|
if !iptClient.IsIPv6() { // ipv6 doesn't have this issue
|
|
// Set up the KUBE-FIREWALL chain and martian packet protection rule.
|
|
// (See below.)
|
|
if _, err := iptClient.EnsureChain(utiliptables.TableFilter, KubeFirewallChain); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that filter table KUBE-FIREWALL chain exists")
|
|
return false
|
|
}
|
|
|
|
if _, err := iptClient.EnsureRule(utiliptables.Prepend, utiliptables.TableFilter, utiliptables.ChainOutput, "-j", string(KubeFirewallChain)); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that OUTPUT chain jumps to KUBE-FIREWALL")
|
|
return false
|
|
}
|
|
if _, err := iptClient.EnsureRule(utiliptables.Prepend, utiliptables.TableFilter, utiliptables.ChainInput, "-j", string(KubeFirewallChain)); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that INPUT chain jumps to KUBE-FIREWALL")
|
|
return false
|
|
}
|
|
|
|
// Kube-proxy's use of `route_localnet` to enable NodePorts on localhost
|
|
// creates a security hole (https://issue.k8s.io/90259) which this
|
|
// iptables rule mitigates. This rule should have been added to
|
|
// kube-proxy, but it mistakenly ended up in kubelet instead, and we are
|
|
// keeping it in kubelet for now in case other third-party components
|
|
// depend on it.
|
|
if _, err := iptClient.EnsureRule(utiliptables.Append, utiliptables.TableFilter, KubeFirewallChain,
|
|
"-m", "comment", "--comment", "block incoming localnet connections",
|
|
"--dst", "127.0.0.0/8",
|
|
"!", "--src", "127.0.0.0/8",
|
|
"-m", "conntrack",
|
|
"!", "--ctstate", "RELATED,ESTABLISHED,DNAT",
|
|
"-j", "DROP"); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure rule to drop invalid localhost packets in filter table KUBE-FIREWALL chain")
|
|
return false
|
|
}
|
|
}
|
|
|
|
if !utilfeature.DefaultFeatureGate.Enabled(features.IPTablesOwnershipCleanup) {
|
|
ok := kl.syncIPTablesRulesDeprecated(iptClient)
|
|
if !ok {
|
|
return false
|
|
}
|
|
}
|
|
|
|
return true
|
|
}
|
|
|
|
// syncIPTablesRulesDeprecated ensures deprecated iptables rules are present:
|
|
// 1. In nat table, KUBE-MARK-DROP rule to mark connections for dropping
|
|
// Marked connection will be drop on INPUT/OUTPUT Chain in filter table
|
|
// 2. In nat table, KUBE-MARK-MASQ rule to mark connections for SNAT
|
|
// Marked connection will get SNAT on POSTROUTING Chain in nat table
|
|
func (kl *Kubelet) syncIPTablesRulesDeprecated(iptClient utiliptables.Interface) bool {
|
|
// Setup KUBE-MARK-DROP rules
|
|
dropMark := getIPTablesMark(kl.iptablesDropBit)
|
|
if _, err := iptClient.EnsureChain(utiliptables.TableNAT, KubeMarkDropChain); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that KUBE-MARK-DROP chain exists")
|
|
return false
|
|
}
|
|
if _, err := iptClient.EnsureRule(utiliptables.Append, utiliptables.TableNAT, KubeMarkDropChain, "-j", "MARK", "--or-mark", dropMark); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that KUBE-MARK-DROP rule exists")
|
|
return false
|
|
}
|
|
if _, err := iptClient.EnsureChain(utiliptables.TableFilter, KubeFirewallChain); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that KUBE-FIREWALL chain exists")
|
|
return false
|
|
}
|
|
if _, err := iptClient.EnsureRule(utiliptables.Append, utiliptables.TableFilter, KubeFirewallChain,
|
|
"-m", "comment", "--comment", "kubernetes firewall for dropping marked packets",
|
|
"-m", "mark", "--mark", fmt.Sprintf("%s/%s", dropMark, dropMark),
|
|
"-j", "DROP"); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that KUBE-FIREWALL rule exists")
|
|
return false
|
|
}
|
|
|
|
// Setup KUBE-MARK-MASQ rules
|
|
masqueradeMark := getIPTablesMark(kl.iptablesMasqueradeBit)
|
|
if _, err := iptClient.EnsureChain(utiliptables.TableNAT, KubeMarkMasqChain); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that KUBE-MARK-MASQ chain exists")
|
|
return false
|
|
}
|
|
if _, err := iptClient.EnsureChain(utiliptables.TableNAT, KubePostroutingChain); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that KUBE-POSTROUTING chain exists")
|
|
return false
|
|
}
|
|
if _, err := iptClient.EnsureRule(utiliptables.Append, utiliptables.TableNAT, KubeMarkMasqChain, "-j", "MARK", "--or-mark", masqueradeMark); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that KUBE-MARK-MASQ rule exists")
|
|
return false
|
|
}
|
|
if _, err := iptClient.EnsureRule(utiliptables.Prepend, utiliptables.TableNAT, utiliptables.ChainPostrouting,
|
|
"-m", "comment", "--comment", "kubernetes postrouting rules", "-j", string(KubePostroutingChain)); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure that POSTROUTING chain jumps to KUBE-POSTROUTING")
|
|
return false
|
|
}
|
|
|
|
// Set up KUBE-POSTROUTING to unmark and masquerade marked packets
|
|
// NB: THIS MUST MATCH the corresponding code in the iptables and ipvs
|
|
// modes of kube-proxy
|
|
if _, err := iptClient.EnsureRule(utiliptables.Append, utiliptables.TableNAT, KubePostroutingChain,
|
|
"-m", "mark", "!", "--mark", fmt.Sprintf("%s/%s", masqueradeMark, masqueradeMark),
|
|
"-j", "RETURN"); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure first masquerading rule exists")
|
|
return false
|
|
}
|
|
// Clear the mark to avoid re-masquerading if the packet re-traverses the network stack.
|
|
// We know the mark bit is currently set so we can use --xor-mark to clear it (without needing
|
|
// to Sprintf another bitmask).
|
|
if _, err := iptClient.EnsureRule(utiliptables.Append, utiliptables.TableNAT, KubePostroutingChain,
|
|
"-j", "MARK", "--xor-mark", masqueradeMark); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure second masquerading rule exists")
|
|
return false
|
|
}
|
|
masqRule := []string{
|
|
"-m", "comment", "--comment", "kubernetes service traffic requiring SNAT",
|
|
"-j", "MASQUERADE",
|
|
}
|
|
if iptClient.HasRandomFully() {
|
|
masqRule = append(masqRule, "--random-fully")
|
|
}
|
|
if _, err := iptClient.EnsureRule(utiliptables.Append, utiliptables.TableNAT, KubePostroutingChain, masqRule...); err != nil {
|
|
klog.ErrorS(err, "Failed to ensure third masquerading rule exists")
|
|
return false
|
|
}
|
|
|
|
return true
|
|
}
|
|
|
|
// getIPTablesMark returns the fwmark given the bit
|
|
func getIPTablesMark(bit int) string {
|
|
value := 1 << uint(bit)
|
|
return fmt.Sprintf("%#08x", value)
|
|
}
|