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Merge pull request #110291 from danwinship/kep-3178-iptables-cleanup-kubelet

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Implement KEP-3178 "iptables cleanup" in kubelet
This commit is contained in:
Kubernetes Prow Robot 2022-08-01 07:50:40 -07:00 committed by GitHub
commit ef8e7c471e
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3 changed files with 90 additions and 70 deletions
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9
pkg/features/kube_features.go
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@ -438,6 +438,13 @@ const (
// Allows Job controller to manage Pod completions per completion index.
IndexedJob featuregate.Feature = "IndexedJob"
// owner: @danwinship
// kep: http://kep.k8s.io/3178
// alpha: v1.25
//
// Causes kubelet to no longer create legacy IPTables rules
IPTablesOwnershipCleanup featuregate.Feature = "IPTablesOwnershipCleanup"
// owner: @ahg
// beta: v1.23
//
@ -938,6 +945,8 @@ var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureS
IndexedJob: {Default: true, PreRelease: featuregate.GA, LockToDefault: true}, // remove in 1.26
IPTablesOwnershipCleanup: {Default: false, PreRelease: featuregate.Alpha},
JobMutableNodeSchedulingDirectives: {Default: true, PreRelease: featuregate.Beta},
JobReadyPods: {Default: true, PreRelease: featuregate.Beta},

147
pkg/kubelet/kubelet_network_linux.go
View File

@ -24,10 +24,11 @@ import (
"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"
utilnet "k8s.io/utils/net"
)
const (
@ -51,73 +52,61 @@ const (
func (kl *Kubelet) initNetworkUtil() {
exec := utilexec.New()
// TODO: @khenidak review when there is no IPv6 iptables exec what should happen here (note: no error returned from this func)
ipv6Primary := kl.nodeIPs != nil && utilnet.IsIPv6(kl.nodeIPs[0])
var iptClients []utiliptables.Interface
var protocols []utiliptables.Protocol
// assume 4,6
protocols = append(protocols, utiliptables.ProtocolIPv4)
iptClients = append(iptClients, utiliptables.New(exec, utiliptables.ProtocolIPv4))
protocols = append(protocols, utiliptables.ProtocolIPv6)
iptClients = append(iptClients, utiliptables.New(exec, utiliptables.ProtocolIPv6))
// and if they are not
if ipv6Primary {
protocols[0], protocols[1] = protocols[1], protocols[0]
iptClients[0], iptClients[1] = iptClients[1], iptClients[0]
iptClients := []utiliptables.Interface{
utiliptables.New(exec, utiliptables.ProtocolIPv4),
utiliptables.New(exec, utiliptables.ProtocolIPv6),
}
for i := range iptClients {
iptClient := iptClients[i]
if kl.syncNetworkUtil(iptClient) {
klog.InfoS("Initialized protocol iptables rules.", "protocol", protocols[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.syncNetworkUtil(iptClient) },
func() { kl.syncIPTablesRules(iptClient) },
1*time.Minute, wait.NeverStop,
)
} else {
klog.InfoS("Failed to initialize protocol iptables rules; some functionality may be missing.", "protocol", protocols[i])
klog.InfoS("Failed to initialize iptables rules; some functionality may be missing.", "protocol", iptClient.Protocol())
}
}
}
// syncNetworkUtil ensures the network utility are present on host.
// Network util includes:
// 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) syncNetworkUtil(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 nat chain exists KUBE-MARK-DROP chain")
return false
}
if _, err := iptClient.EnsureRule(utiliptables.Append, utiliptables.TableNAT, KubeMarkDropChain, "-j", "MARK", "--or-mark", dropMark); err != nil {
klog.ErrorS(err, "Failed to ensure marking rule for KUBE-MARK-DROP chain")
return false
}
if _, err := iptClient.EnsureChain(utiliptables.TableFilter, KubeFirewallChain); err != nil {
klog.ErrorS(err, "Failed to ensure that filter table exists KUBE-FIREWALL chain")
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 rule to drop packet marked by the KUBE-MARK-DROP in KUBE-FIREWALL chain")
// 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
}
// drop all non-local packets to localhost if they're not part of an existing
// forwarded connection. See #90259
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",
@ -130,32 +119,61 @@ func (kl *Kubelet) syncNetworkUtil(iptClient utiliptables.Interface) bool {
}
}
if _, err := iptClient.EnsureRule(utiliptables.Prepend, utiliptables.TableFilter, utiliptables.ChainOutput, "-j", string(KubeFirewallChain)); err != nil {
klog.ErrorS(err, "Failed to ensure that filter table from OUTPUT chain jumps to KUBE-FIREWALL chain")
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.Prepend, utiliptables.TableFilter, utiliptables.ChainInput, "-j", string(KubeFirewallChain)); err != nil {
klog.ErrorS(err, "Failed to ensure that filter table INPUT chain jumps to KUBE-FIREWALL chain")
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 nat table exists KUBE-MARK-MASQ chain")
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 nat table exists kube POSTROUTING chain")
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 marking rule for KUBE-MARK-MASQ chain")
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 nat table from POSTROUTING chain jumps to KUBE-POSTROUTING chain")
klog.ErrorS(err, "Failed to ensure that POSTROUTING chain jumps to KUBE-POSTROUTING")
return false
}
@ -165,7 +183,7 @@ func (kl *Kubelet) syncNetworkUtil(iptClient utiliptables.Interface) bool {
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 filtering rule for KUBE-POSTROUTING chain")
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.
@ -173,7 +191,7 @@ func (kl *Kubelet) syncNetworkUtil(iptClient utiliptables.Interface) bool {
// 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 unmarking rule for KUBE-POSTROUTING chain")
klog.ErrorS(err, "Failed to ensure second masquerading rule exists")
return false
}
masqRule := []string{
@ -184,14 +202,7 @@ func (kl *Kubelet) syncNetworkUtil(iptClient utiliptables.Interface) bool {
masqRule = append(masqRule, "--random-fully")
}
if _, err := iptClient.EnsureRule(utiliptables.Append, utiliptables.TableNAT, KubePostroutingChain, masqRule...); err != nil {
klog.ErrorS(err, "Failed to ensure SNAT rule for packets marked by KUBE-MARK-MASQ chain in nat table KUBE-POSTROUTING chain")
return false
}
// 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")
klog.ErrorS(err, "Failed to ensure third masquerading rule exists")
return false
}

4
test/e2e/network/networking.go
View File

@ -618,13 +618,13 @@ var _ = common.SIGDescribe("Networking", func() {
ginkgo.By("verifying that kubelet rules are eventually recreated")
err = utilwait.PollImmediate(framework.Poll, framework.RestartNodeReadyAgainTimeout, func() (bool, error) {
result, err = e2essh.SSH("sudo iptables-save -t nat", host, framework.TestContext.Provider)
result, err = e2essh.SSH("sudo iptables-save -t mangle", host, framework.TestContext.Provider)
if err != nil || result.Code != 0 {
e2essh.LogResult(result)
return false, err
}
if strings.Contains(result.Stdout, "\n-A KUBE-MARK-DROP ") {
if strings.Contains(result.Stdout, "\n:KUBE-IPTABLES-HINT") {
return true, nil
}
return false, nil