Port service/endpoint chain creation/cleanup to nftables

pkg/proxy/nftables/proxier.go

@@ -21,7 +21,6 @@ package nftables
 //
 
 import (
-	"bytes"
 	"context"
 	"crypto/sha256"
 	"encoding/base32"
@@ -103,12 +102,13 @@ func newServiceInfo(port *v1.ServicePort, service *v1.Service, bsvcPortInfo *pro
 	// Store the following for performance reasons.
 	svcName := types.NamespacedName{Namespace: service.Namespace, Name: service.Name}
 	svcPortName := proxy.ServicePortName{NamespacedName: svcName, Port: port.Name}
-	protocol := strings.ToLower(string(svcPort.Protocol()))
 	svcPort.nameString = svcPortName.String()
-	svcPort.clusterPolicyChainName = servicePortPolicyClusterChain(svcPort.nameString, protocol)
-	svcPort.localPolicyChainName = servicePortPolicyLocalChainName(svcPort.nameString, protocol)
-	svcPort.firewallChainName = serviceFirewallChainName(svcPort.nameString, protocol)
-	svcPort.externalChainName = serviceExternalChainName(svcPort.nameString, protocol)
+
+	chainNameBase := servicePortChainNameBase(&svcPortName, strings.ToLower(string(svcPort.Protocol())))
+	svcPort.clusterPolicyChainName = servicePortPolicyClusterChainNamePrefix + chainNameBase
+	svcPort.localPolicyChainName = servicePortPolicyLocalChainNamePrefix + chainNameBase
+	svcPort.firewallChainName = serviceFirewallChainNamePrefix + chainNameBase
+	svcPort.externalChainName = serviceExternalChainNamePrefix + chainNameBase
 
 	return svcPort
 }
@@ -124,7 +124,7 @@ type endpointInfo struct {
 func newEndpointInfo(baseInfo *proxy.BaseEndpointInfo, svcPortName *proxy.ServicePortName) proxy.Endpoint {
 	return &endpointInfo{
 		BaseEndpointInfo: baseInfo,
-		chainName:        servicePortEndpointChainName(svcPortName.String(), strings.ToLower(string(svcPortName.Protocol)), baseInfo.String()),
+		chainName:        servicePortEndpointChainNamePrefix + servicePortEndpointChainNameBase(svcPortName, strings.ToLower(string(svcPortName.Protocol)), baseInfo.String()),
 	}
 }
 
@@ -174,11 +174,8 @@ type Proxier struct {
 
 	// The following buffers are used to reuse memory and avoid allocations
 	// that are significantly impacting performance.
-	iptablesData *bytes.Buffer
-	filterChains proxyutil.LineBuffer
-	filterRules  proxyutil.LineBuffer
-	natChains    proxyutil.LineBuffer
-	natRules     proxyutil.LineBuffer
+	filterRules proxyutil.LineBuffer
+	natRules    proxyutil.LineBuffer
 
 	// conntrackTCPLiberal indicates whether the system sets the kernel nf_conntrack_tcp_be_liberal
 	conntrackTCPLiberal bool
@@ -188,6 +185,9 @@ type Proxier struct {
 	// networkInterfacer defines an interface for several net library functions.
 	// Inject for test purpose.
 	networkInterfacer proxyutil.NetworkInterfacer
+
+	// staleChains contains information about chains to be deleted later
+	staleChains map[string]time.Time
 }
 
 // Proxier implements proxy.Provider
@@ -263,14 +263,12 @@ func NewProxier(ipFamily v1.IPFamily,
 		serviceHealthServer:      serviceHealthServer,
 		healthzServer:            healthzServer,
 		precomputedProbabilities: make([]string, 0, 1001),
-		iptablesData:             bytes.NewBuffer(nil),
-		filterChains:             proxyutil.NewLineBuffer(),
 		filterRules:              proxyutil.NewLineBuffer(),
-		natChains:                proxyutil.NewLineBuffer(),
 		natRules:                 proxyutil.NewLineBuffer(),
 		nodePortAddresses:        nodePortAddresses,
 		networkInterfacer:        proxyutil.RealNetwork{},
 		conntrackTCPLiberal:      conntrackTCPLiberal,
+		staleChains:              make(map[string]time.Time),
 	}
 
 	burstSyncs := 2
@@ -667,75 +665,113 @@ func (proxier *Proxier) OnNodeDelete(node *v1.Node) {
 func (proxier *Proxier) OnNodeSynced() {
 }
 
-// portProtoHash takes the ServicePortName and protocol for a service
-// returns the associated 16 character hash. This is computed by hashing (sha256)
-// then encoding to base32 and truncating to 16 chars. We do this because IPTables
-// Chain Names must be <= 28 chars long, and the longer they are the harder they are to read.
-func portProtoHash(servicePortName string, protocol string) string {
-	hash := sha256.Sum256([]byte(servicePortName + protocol))
-	encoded := base32.StdEncoding.EncodeToString(hash[:])
-	return encoded[:16]
-}
-
 const (
-	servicePortPolicyClusterChainNamePrefix = "KUBE-SVC-"
-	servicePortPolicyLocalChainNamePrefix   = "KUBE-SVL-"
-	serviceFirewallChainNamePrefix          = "KUBE-FW-"
-	serviceExternalChainNamePrefix          = "KUBE-EXT-"
-	servicePortEndpointChainNamePrefix      = "KUBE-SEP-"
+	// Maximum length for one of our chain name prefixes, including the trailing
+	// hyphen.
+	chainNamePrefixLengthMax = 16
+
+	// Maximum length of the string returned from servicePortChainNameBase or
+	// servicePortEndpointChainNameBase.
+	chainNameBaseLengthMax = knftables.NameLengthMax - chainNamePrefixLengthMax
 )
 
-// servicePortPolicyClusterChain returns the name of the KUBE-SVC-XXXX chain for a service, which is the
-// main iptables chain for that service, used for dispatching to endpoints when using `Cluster`
-// traffic policy.
-func servicePortPolicyClusterChain(servicePortName string, protocol string) string {
-	return servicePortPolicyClusterChainNamePrefix + portProtoHash(servicePortName, protocol)
-}
+const (
+	servicePortPolicyClusterChainNamePrefix = "service-"
+	servicePortPolicyLocalChainNamePrefix   = "local-"
+	serviceFirewallChainNamePrefix          = "firewall-"
+	serviceExternalChainNamePrefix          = "external-"
+	servicePortEndpointChainNamePrefix      = "endpoint-"
+)
 
-// servicePortPolicyLocalChainName returns the name of the KUBE-SVL-XXXX chain for a service, which
-// handles dispatching to local endpoints when using `Local` traffic policy. This chain only
-// exists if the service has `Local` internal or external traffic policy.
-func servicePortPolicyLocalChainName(servicePortName string, protocol string) string {
-	return servicePortPolicyLocalChainNamePrefix + portProtoHash(servicePortName, protocol)
-}
-
-// serviceFirewallChainName returns the name of the KUBE-FW-XXXX chain for a service, which
-// is used to implement the filtering for the LoadBalancerSourceRanges feature.
-func serviceFirewallChainName(servicePortName string, protocol string) string {
-	return serviceFirewallChainNamePrefix + portProtoHash(servicePortName, protocol)
-}
-
-// serviceExternalChainName returns the name of the KUBE-EXT-XXXX chain for a service, which
-// implements "short-circuiting" for internally-originated external-destination traffic when using
-// `Local` external traffic policy.  It forwards traffic from local sources to the KUBE-SVC-XXXX
-// chain and traffic from external sources to the KUBE-SVL-XXXX chain.
-func serviceExternalChainName(servicePortName string, protocol string) string {
-	return serviceExternalChainNamePrefix + portProtoHash(servicePortName, protocol)
-}
-
-// servicePortEndpointChainName returns the name of the KUBE-SEP-XXXX chain for a particular
-// service endpoint.
-func servicePortEndpointChainName(servicePortName string, protocol string, endpoint string) string {
-	hash := sha256.Sum256([]byte(servicePortName + protocol + endpoint))
+// hashAndTruncate prefixes name with a hash of itself and then truncates to
+// chainNameBaseLengthMax. The hash ensures that (a) the name is still unique if we have
+// to truncate the end, and (b) it's visually distinguishable from other chains that would
+// otherwise have nearly identical names (e.g., different endpoint chains for a given
+// service that differ in only a single digit).
+func hashAndTruncate(name string) string {
+	hash := sha256.Sum256([]byte(name))
 	encoded := base32.StdEncoding.EncodeToString(hash[:])
-	return servicePortEndpointChainNamePrefix + encoded[:16]
+	name = encoded[:8] + "-" + name
+	if len(name) > chainNameBaseLengthMax {
+		name = name[:chainNameBaseLengthMax-3] + "..."
+	}
+	return name
+}
+
+// servicePortChainNameBase returns the base name for a chain for the given ServicePort.
+// This is something like "HASH-namespace/serviceName/protocol/portName", e.g,
+// "ULMVA6XW-ns1/svc1/tcp/p80".
+func servicePortChainNameBase(servicePortName *proxy.ServicePortName, protocol string) string {
+	// nftables chains can contain the characters [A-Za-z0-9_./-] (but must start with
+	// a letter, underscore, or dot).
+	//
+	// Namespace, Service, and Port names can contain [a-z0-9-] (with some additional
+	// restrictions that aren't relevant here).
+	//
+	// Protocol is /(tcp|udp|sctp)/.
+	//
+	// Thus, we can safely use all Namespace names, Service names, protocol values,
+	// and Port names directly in nftables chain names (though note that this assumes
+	// that the chain name won't *start* with any of those strings, since that might
+	// be illegal). We use "/" to separate the parts of the name, which is one of the
+	// two characters allowed in a chain name that isn't allowed in our input strings.
+
+	name := fmt.Sprintf("%s/%s/%s/%s",
+		servicePortName.NamespacedName.Namespace,
+		servicePortName.NamespacedName.Name,
+		protocol,
+		servicePortName.Port,
+	)
+
+	// The namespace, service, and port name can each be up to 63 characters, protocol
+	// can be up to 4, plus 8 for the hash and 4 additional punctuation characters.
+	// That's a total of 205, which is less than chainNameBaseLengthMax (240). So this
+	// will never actually return a truncated name.
+	return hashAndTruncate(name)
+}
+
+// servicePortEndpointChainNameBase returns the suffix for chain names for the given
+// endpoint. This is something like
+// "HASH-namespace/serviceName/protocol/portName__endpointIP/endpointport", e.g.,
+// "5OJB2KTY-ns1/svc1/tcp/p80__10.180.0.1/80".
+func servicePortEndpointChainNameBase(servicePortName *proxy.ServicePortName, protocol, endpoint string) string {
+	// As above in servicePortChainNameBase: Namespace, Service, Port, Protocol, and
+	// EndpointPort are all safe to copy into the chain name directly. But if
+	// EndpointIP is IPv6 then it will contain colons, which aren't allowed in a chain
+	// name. IPv6 IPs are also quite long, but we can't safely truncate them (e.g. to
+	// only the final segment) because (especially for manually-created external
+	// endpoints), we can't know for sure that any part of them is redundant.
+
+	endpointIP, endpointPort, _ := net.SplitHostPort(endpoint)
+	if strings.Contains(endpointIP, ":") {
+		endpointIP = strings.ReplaceAll(endpointIP, ":", ".")
+	}
+
+	// As above, we use "/" to separate parts of the name, and "__" to separate the
+	// "service" part from the "endpoint" part.
+	name := fmt.Sprintf("%s/%s/%s/%s__%s/%s",
+		servicePortName.NamespacedName.Namespace,
+		servicePortName.NamespacedName.Name,
+		protocol,
+		servicePortName.Port,
+		endpointIP,
+		endpointPort,
+	)
+
+	// The part of name before the "__" can be up to 205 characters (as with
+	// servicePortChainNameBase above). An IPv6 address can be up to 39 characters, and
+	// a port can be up to 5 digits, plus 3 punctuation characters gives a max total
+	// length of 252, well over chainNameBaseLengthMax (240), so truncation is
+	// theoretically possible (though incredibly unlikely).
+	return hashAndTruncate(name)
 }
 
 func isServiceChainName(chainString string) bool {
-	prefixes := []string{
-		servicePortPolicyClusterChainNamePrefix,
-		servicePortPolicyLocalChainNamePrefix,
-		servicePortEndpointChainNamePrefix,
-		serviceFirewallChainNamePrefix,
-		serviceExternalChainNamePrefix,
-	}
-
-	for _, p := range prefixes {
-		if strings.HasPrefix(chainString, p) {
-			return true
-		}
-	}
-	return false
+	// The chains returned from servicePortChainNameBase and
+	// servicePortEndpointChainNameBase will always have at least one "/" in them.
+	// Since none of our "stock" chain names use slashes, we can distinguish them this
+	// way.
+	return strings.Contains(chainString, "/")
 }
 
 // This is where all of the nftables calls happen.
@@ -774,18 +810,45 @@ func (proxier *Proxier) syncProxyRules() {
 		}
 	}()
 
+	// If there are sufficiently-stale chains left over from previous transactions,
+	// try to delete them now.
+	if len(proxier.staleChains) > 0 {
+		oneSecondAgo := start.Add(-time.Second)
+		tx := proxier.nftables.NewTransaction()
+		deleted := 0
+		for chain, modtime := range proxier.staleChains {
+			if modtime.Before(oneSecondAgo) {
+				tx.Delete(&knftables.Chain{
+					Name: chain,
+				})
+				delete(proxier.staleChains, chain)
+				deleted++
+			}
+		}
+		if deleted > 0 {
+			klog.InfoS("Deleting stale nftables chains", "numChains", deleted)
+			err := proxier.nftables.Run(context.TODO(), tx)
+			if err != nil {
+				// We already deleted the entries from staleChains, but if
+				// the chains still exist, they'll just get added back
+				// (with a later timestamp) at the end of the sync.
+				klog.ErrorS(err, "Unable to delete stale chains; will retry later")
+				// FIXME: metric
+			}
+		}
+	}
+
+	// Now start the actual syncing transaction
 	tx := proxier.nftables.NewTransaction()
 	proxier.setupNFTables(tx)
 
 	// Reset all buffers used later.
 	// This is to avoid memory reallocations and thus improve performance.
-	proxier.filterChains.Reset()
 	proxier.filterRules.Reset()
-	proxier.natChains.Reset()
 	proxier.natRules.Reset()
 
-	// Accumulate NAT chains to keep.
-	activeNATChains := sets.New[string]()
+	// Accumulate service/endpoint chains to keep.
+	activeChains := sets.New[string]()
 
 	// Compute total number of endpoint chains across all services
 	// to get a sense of how big the cluster is.
@@ -819,7 +882,7 @@ func (proxier *Proxier) syncProxyRules() {
 		// Note the endpoint chains that will be used
 		for _, ep := range allLocallyReachableEndpoints {
 			if epInfo, ok := ep.(*endpointInfo); ok {
-				activeNATChains.Insert(epInfo.chainName)
+				ensureChain(epInfo.chainName, tx, activeChains)
 			}
 		}
 
@@ -827,14 +890,14 @@ func (proxier *Proxier) syncProxyRules() {
 		clusterPolicyChain := svcInfo.clusterPolicyChainName
 		usesClusterPolicyChain := len(clusterEndpoints) > 0 && svcInfo.UsesClusterEndpoints()
 		if usesClusterPolicyChain {
-			activeNATChains.Insert(clusterPolicyChain)
+			ensureChain(clusterPolicyChain, tx, activeChains)
 		}
 
 		// localPolicyChain contains the endpoints used with "Local" traffic policy
 		localPolicyChain := svcInfo.localPolicyChainName
 		usesLocalPolicyChain := len(localEndpoints) > 0 && svcInfo.UsesLocalEndpoints()
 		if usesLocalPolicyChain {
-			activeNATChains.Insert(localPolicyChain)
+			ensureChain(localPolicyChain, tx, activeChains)
 		}
 
 		// internalPolicyChain is the chain containing the endpoints for
@@ -876,7 +939,7 @@ func (proxier *Proxier) syncProxyRules() {
 		// are no externally-usable endpoints.
 		usesExternalTrafficChain := hasEndpoints && svcInfo.ExternallyAccessible()
 		if usesExternalTrafficChain {
-			activeNATChains.Insert(externalTrafficChain)
+			ensureChain(externalTrafficChain, tx, activeChains)
 		}
 
 		// Traffic to LoadBalancer IPs can go directly to externalTrafficChain
@@ -886,7 +949,7 @@ func (proxier *Proxier) syncProxyRules() {
 		fwChain := svcInfo.firewallChainName
 		usesFWChain := hasEndpoints && len(svcInfo.LoadBalancerVIPStrings()) > 0 && len(svcInfo.LoadBalancerSourceRanges()) > 0
 		if usesFWChain {
-			activeNATChains.Insert(fwChain)
+			ensureChain(fwChain, tx, activeChains)
 			loadBalancerTrafficChain = fwChain
 		}
 
@@ -1069,8 +1132,6 @@ func (proxier *Proxier) syncProxyRules() {
 		// jump to externalTrafficChain, which will handle some special cases and
 		// then jump to externalPolicyChain.
 		if usesExternalTrafficChain {
-			proxier.natChains.Write(utiliptables.MakeChainLine(utiliptables.Chain(externalTrafficChain)))
-
 			if !svcInfo.ExternalPolicyLocal() {
 				// If we are using non-local endpoints we need to masquerade,
 				// in case we cross nodes.
@@ -1123,8 +1184,6 @@ func (proxier *Proxier) syncProxyRules() {
 
 		// Set up firewall chain, if needed
 		if usesFWChain {
-			proxier.natChains.Write(utiliptables.MakeChainLine(utiliptables.Chain(fwChain)))
-
 			// The service firewall rules are created based on the
 			// loadBalancerSourceRanges field. This only works for VIP-like
 			// loadbalancers that preserve source IPs. For loadbalancers which
@@ -1171,17 +1230,15 @@ func (proxier *Proxier) syncProxyRules() {
 			)
 		}
 
-		// If Cluster policy is in use, create the chain and create rules jumping
-		// from clusterPolicyChain to the clusterEndpoints
+		// If Cluster policy is in use, create rules jumping from
+		// clusterPolicyChain to the clusterEndpoints
 		if usesClusterPolicyChain {
-			proxier.natChains.Write(utiliptables.MakeChainLine(utiliptables.Chain(clusterPolicyChain)))
 			proxier.writeServiceToEndpointRules(svcPortNameString, svcInfo, clusterPolicyChain, clusterEndpoints)
 		}
 
-		// If Local policy is in use, create the chain and create rules jumping
-		// from localPolicyChain to the localEndpoints
+		// If Local policy is in use, create rules jumping from localPolicyChain
+		// to the localEndpoints
 		if usesLocalPolicyChain {
-			proxier.natChains.Write(utiliptables.MakeChainLine(utiliptables.Chain(localPolicyChain)))
 			proxier.writeServiceToEndpointRules(svcPortNameString, svcInfo, localPolicyChain, localEndpoints)
 		}
 
@@ -1195,10 +1252,6 @@ func (proxier *Proxier) syncProxyRules() {
 
 			endpointChain := epInfo.chainName
 
-			// Create the endpoint chain
-			proxier.natChains.Write(utiliptables.MakeChainLine(utiliptables.Chain(endpointChain)))
-			activeNATChains.Insert(endpointChain)
-
 			// Handle traffic that loops back to the originator with SNAT.
 			proxier.natRules.Write(
 				"-A", string(endpointChain),
@@ -1220,33 +1273,6 @@ func (proxier *Proxier) syncProxyRules() {
 		}
 	}
 
-	// Delete chains no longer in use.
-	deletedChains := 0
-	var existingNATChains map[utiliptables.Chain]struct{}
-
-	proxier.iptablesData.Reset()
-	if err := proxier.iptables.SaveInto(utiliptables.TableNAT, proxier.iptablesData); err == nil {
-		existingNATChains = utiliptables.GetChainsFromTable(proxier.iptablesData.Bytes())
-
-		for chain := range existingNATChains {
-			if !activeNATChains.Has(string(chain)) {
-				chainString := string(chain)
-				if !isServiceChainName(chainString) {
-					// Ignore chains that aren't ours.
-					continue
-				}
-				// We must (as per iptables) write a chain-line
-				// for it, which has the nice effect of flushing
-				// the chain. Then we can remove the chain.
-				proxier.natChains.Write(utiliptables.MakeChainLine(chain))
-				proxier.natRules.Write("-X", chainString)
-				deletedChains++
-			}
-		}
-	} else {
-		klog.ErrorS(err, "Failed to execute iptables-save: stale chains will not be deleted")
-	}
-
 	// Finally, tail-call to the nodePorts chain.  This needs to be after all
 	// other service portal rules.
 	if proxier.nodePortAddresses.MatchAll() {
@@ -1285,23 +1311,41 @@ func (proxier *Proxier) syncProxyRules() {
 		}
 	}
 
+	// Figure out which chains are now stale. Unfortunately, we can't delete them
+	// right away, because with kernels before 6.2, if there is a map element pointing
+	// to a chain, and you delete that map element, the kernel doesn't notice until a
+	// short amount of time later that the chain is now unreferenced. So we flush them
+	// now, and record the time that they become stale in staleChains so they can be
+	// deleted later.
+	existingChains, err := proxier.nftables.List(context.TODO(), "chains")
+	if err == nil {
+		for _, chain := range existingChains {
+			if isServiceChainName(chain) && !activeChains.Has(chain) {
+				tx.Flush(&knftables.Chain{
+					Name: chain,
+				})
+				proxier.staleChains[chain] = start
+			}
+		}
+	} else if !knftables.IsNotFound(err) {
+		klog.ErrorS(err, "Failed to list nftables chains: stale chains will not be deleted")
+	}
+
 	metrics.IptablesRulesTotal.WithLabelValues(string(utiliptables.TableFilter)).Set(float64(proxier.filterRules.Lines()))
-	metrics.IptablesRulesTotal.WithLabelValues(string(utiliptables.TableNAT)).Set(float64(proxier.natRules.Lines() - deletedChains))
+	metrics.IptablesRulesTotal.WithLabelValues(string(utiliptables.TableNAT)).Set(float64(proxier.natRules.Lines()))
 
 	// Sync rules.
 	klog.V(2).InfoS("Reloading service nftables data",
 		"numServices", len(proxier.svcPortMap),
 		"numEndpoints", totalEndpoints,
-		"numFilterChains", proxier.filterChains.Lines(),
 		"numFilterRules", proxier.filterRules.Lines(),
-		"numNATChains", proxier.natChains.Lines(),
 		"numNATRules", proxier.natRules.Lines(),
 	)
 
 	// FIXME
 	// klog.V(9).InfoS("Running nftables transaction", "transaction", tx.Bytes())
 
-	err := proxier.nftables.Run(context.TODO(), tx)
+	err = proxier.nftables.Run(context.TODO(), tx)
 	if err != nil {
 		klog.ErrorS(err, "nftables sync failed")
 		metrics.IptablesRestoreFailuresTotal.Inc()

pkg/proxy/nftables/proxier_test.go

@@ -17,7 +17,6 @@ limitations under the License.
 package nftables
 
 import (
-	"bytes"
 	"fmt"
 	"net"
 	"reflect"
@@ -322,14 +321,12 @@ func NewFakeProxier(ipFamily v1.IPFamily) (*knftables.Fake, *Proxier) {
 		hostname:                 testHostname,
 		serviceHealthServer:      healthcheck.NewFakeServiceHealthServer(),
 		precomputedProbabilities: make([]string, 0, 1001),
-		iptablesData:             bytes.NewBuffer(nil),
-		filterChains:             proxyutil.NewLineBuffer(),
 		filterRules:              proxyutil.NewLineBuffer(),
-		natChains:                proxyutil.NewLineBuffer(),
 		natRules:                 proxyutil.NewLineBuffer(),
 		nodeIP:                   netutils.ParseIPSloppy(testNodeIP),
 		nodePortAddresses:        proxyutil.NewNodePortAddresses(ipFamily, nil),
 		networkInterfacer:        networkInterfacer,
+		staleChains:              make(map[string]time.Time),
 	}
 	p.setInitialized(true)
 	p.syncRunner = async.NewBoundedFrequencyRunner("test-sync-runner", p.syncProxyRules, 0, time.Minute, 1)
@@ -534,6 +531,32 @@ func TestOverallNFTablesRules(t *testing.T) {
 		add rule ip kube-proxy nat-postrouting jump masquerading
 		add chain ip kube-proxy nat-prerouting { type nat hook prerouting priority -100 ; }
 		add rule ip kube-proxy nat-prerouting jump services
+
+		# svc1
+		add chain ip kube-proxy service-ULMVA6XW-ns1/svc1/tcp/p80
+		add chain ip kube-proxy endpoint-5OJB2KTY-ns1/svc1/tcp/p80__10.180.0.1/80
+
+		# svc2
+		add chain ip kube-proxy service-42NFTM6N-ns2/svc2/tcp/p80
+		add chain ip kube-proxy external-42NFTM6N-ns2/svc2/tcp/p80
+		add chain ip kube-proxy endpoint-SGOXE6O3-ns2/svc2/tcp/p80__10.180.0.2/80
+
+		# svc3
+		add chain ip kube-proxy service-4AT6LBPK-ns3/svc3/tcp/p80
+		add chain ip kube-proxy external-4AT6LBPK-ns3/svc3/tcp/p80
+		add chain ip kube-proxy endpoint-UEIP74TE-ns3/svc3/tcp/p80__10.180.0.3/80
+
+		# svc4
+		add chain ip kube-proxy service-LAUZTJTB-ns4/svc4/tcp/p80
+		add chain ip kube-proxy external-LAUZTJTB-ns4/svc4/tcp/p80
+		add chain ip kube-proxy endpoint-5RFCDDV7-ns4/svc4/tcp/p80__10.180.0.5/80
+		add chain ip kube-proxy endpoint-UNZV3OEC-ns4/svc4/tcp/p80__10.180.0.4/80
+
+		# svc5
+		add chain ip kube-proxy service-HVFWP5L3-ns5/svc5/tcp/p80
+		add chain ip kube-proxy external-HVFWP5L3-ns5/svc5/tcp/p80
+		add chain ip kube-proxy firewall-HVFWP5L3-ns5/svc5/tcp/p80
+		add chain ip kube-proxy endpoint-GTK6MW7G-ns5/svc5/tcp/p80__10.180.0.3/80
 		`)
 
 	assertNFTablesTransactionEqual(t, getLine(), expected, nft.Dump())
@@ -4229,6 +4252,14 @@ func TestSyncProxyRulesRepeated(t *testing.T) {
 		add rule ip kube-proxy nat-prerouting jump services
 		`)
 
+	// Helper function to make it look like time has passed (from the point of view of
+	// the stale-chain-deletion code).
+	ageStaleChains := func() {
+		for chain, t := range fp.staleChains {
+			fp.staleChains[chain] = t.Add(-2 * time.Second)
+		}
+	}
+
 	// Create initial state
 	var svc2 *v1.Service
 
@@ -4282,8 +4313,12 @@ func TestSyncProxyRulesRepeated(t *testing.T) {
 	fp.syncProxyRules()
 
 	expected := baseRules + dedent.Dedent(`
-		# FIXME
-		`)
+		add chain ip kube-proxy service-ULMVA6XW-ns1/svc1/tcp/p80
+		add chain ip kube-proxy endpoint-5TPGNJF2-ns1/svc1/tcp/p80__10.0.1.1/80
+
+		add chain ip kube-proxy service-MHHHYRWA-ns2/svc2/tcp/p8080
+		add chain ip kube-proxy endpoint-7RVP4LUQ-ns2/svc2/tcp/p8080__10.0.2.1/8080
+                `)
 	assertNFTablesTransactionEqual(t, getLine(), expected, nft.Dump())
 
 	// Add a new service and its endpoints
@@ -4316,16 +4351,30 @@ func TestSyncProxyRulesRepeated(t *testing.T) {
 	fp.syncProxyRules()
 
 	expected = baseRules + dedent.Dedent(`
-		# FIXME
+		add chain ip kube-proxy service-ULMVA6XW-ns1/svc1/tcp/p80
+		add chain ip kube-proxy endpoint-5TPGNJF2-ns1/svc1/tcp/p80__10.0.1.1/80
+
+		add chain ip kube-proxy service-MHHHYRWA-ns2/svc2/tcp/p8080
+		add chain ip kube-proxy endpoint-7RVP4LUQ-ns2/svc2/tcp/p8080__10.0.2.1/8080
+
+		add chain ip kube-proxy service-4AT6LBPK-ns3/svc3/tcp/p80
+		add chain ip kube-proxy endpoint-2OCDJSZQ-ns3/svc3/tcp/p80__10.0.3.1/80
 		`)
 	assertNFTablesTransactionEqual(t, getLine(), expected, nft.Dump())
 
-	// Delete a service.
+	// Delete a service; its chains will be flushed, but not immediately deleted.
 	fp.OnServiceDelete(svc2)
 	fp.syncProxyRules()
+	assertNFTablesTransactionEqual(t, getLine(), expected, nft.Dump())
 
+	ageStaleChains()
+	fp.syncProxyRules()
 	expected = baseRules + dedent.Dedent(`
-		# FIXME
+		add chain ip kube-proxy service-ULMVA6XW-ns1/svc1/tcp/p80
+		add chain ip kube-proxy endpoint-5TPGNJF2-ns1/svc1/tcp/p80__10.0.1.1/80
+
+		add chain ip kube-proxy service-4AT6LBPK-ns3/svc3/tcp/p80
+		add chain ip kube-proxy endpoint-2OCDJSZQ-ns3/svc3/tcp/p80__10.0.3.1/80
 		`)
 	assertNFTablesTransactionEqual(t, getLine(), expected, nft.Dump())
 
@@ -4343,7 +4392,11 @@ func TestSyncProxyRulesRepeated(t *testing.T) {
 	)
 	fp.syncProxyRules()
 	expected = baseRules + dedent.Dedent(`
-		# FIXME
+		add chain ip kube-proxy service-ULMVA6XW-ns1/svc1/tcp/p80
+		add chain ip kube-proxy endpoint-5TPGNJF2-ns1/svc1/tcp/p80__10.0.1.1/80
+
+		add chain ip kube-proxy service-4AT6LBPK-ns3/svc3/tcp/p80
+		add chain ip kube-proxy endpoint-2OCDJSZQ-ns3/svc3/tcp/p80__10.0.3.1/80
 		`)
 	assertNFTablesTransactionEqual(t, getLine(), expected, nft.Dump())
 
@@ -4362,7 +4415,14 @@ func TestSyncProxyRulesRepeated(t *testing.T) {
 	)
 	fp.syncProxyRules()
 	expected = baseRules + dedent.Dedent(`
-		# FIXME
+		add chain ip kube-proxy service-ULMVA6XW-ns1/svc1/tcp/p80
+		add chain ip kube-proxy endpoint-5TPGNJF2-ns1/svc1/tcp/p80__10.0.1.1/80
+
+		add chain ip kube-proxy service-4AT6LBPK-ns3/svc3/tcp/p80
+		add chain ip kube-proxy endpoint-2OCDJSZQ-ns3/svc3/tcp/p80__10.0.3.1/80
+
+		add chain ip kube-proxy service-LAUZTJTB-ns4/svc4/tcp/p80
+		add chain ip kube-proxy endpoint-WAHRBT2B-ns4/svc4/tcp/p80__10.0.4.1/80
 		`)
 	assertNFTablesTransactionEqual(t, getLine(), expected, nft.Dump())
 
@@ -4372,11 +4432,23 @@ func TestSyncProxyRulesRepeated(t *testing.T) {
 	fp.OnEndpointSliceUpdate(eps3, eps3update)
 	fp.syncProxyRules()
 
+	// The old endpoint chain (for 10.0.3.1) will not be deleted yet.
 	expected = baseRules + dedent.Dedent(`
-		# FIXME
+		add chain ip kube-proxy service-ULMVA6XW-ns1/svc1/tcp/p80
+		add chain ip kube-proxy endpoint-5TPGNJF2-ns1/svc1/tcp/p80__10.0.1.1/80
+
+		add chain ip kube-proxy service-4AT6LBPK-ns3/svc3/tcp/p80
+		add chain ip kube-proxy endpoint-2OCDJSZQ-ns3/svc3/tcp/p80__10.0.3.1/80
+		add chain ip kube-proxy endpoint-SWWHDC7X-ns3/svc3/tcp/p80__10.0.3.2/80
+
+		add chain ip kube-proxy service-LAUZTJTB-ns4/svc4/tcp/p80
+		add chain ip kube-proxy endpoint-WAHRBT2B-ns4/svc4/tcp/p80__10.0.4.1/80
 		`)
 	assertNFTablesTransactionEqual(t, getLine(), expected, nft.Dump())
 
+	// (Ensure the old svc3 chain gets deleted in the next sync.)
+	ageStaleChains()
+
 	// Add an endpoint to a service.
 	eps3update2 := eps3update.DeepCopy()
 	eps3update2.Endpoints = append(eps3update2.Endpoints, discovery.Endpoint{Addresses: []string{"10.0.3.3"}})
@@ -4384,7 +4456,15 @@ func TestSyncProxyRulesRepeated(t *testing.T) {
 	fp.syncProxyRules()
 
 	expected = baseRules + dedent.Dedent(`
-		# FIXME
+		add chain ip kube-proxy service-ULMVA6XW-ns1/svc1/tcp/p80
+		add chain ip kube-proxy endpoint-5TPGNJF2-ns1/svc1/tcp/p80__10.0.1.1/80
+
+		add chain ip kube-proxy service-4AT6LBPK-ns3/svc3/tcp/p80
+		add chain ip kube-proxy endpoint-SWWHDC7X-ns3/svc3/tcp/p80__10.0.3.2/80
+		add chain ip kube-proxy endpoint-TQ2QKHCZ-ns3/svc3/tcp/p80__10.0.3.3/80
+
+		add chain ip kube-proxy service-LAUZTJTB-ns4/svc4/tcp/p80
+		add chain ip kube-proxy endpoint-WAHRBT2B-ns4/svc4/tcp/p80__10.0.4.1/80
 		`)
 	assertNFTablesTransactionEqual(t, getLine(), expected, nft.Dump())
 
@@ -4670,3 +4750,156 @@ func TestLoadBalancerIngressRouteTypeProxy(t *testing.T) {
 		})
 	}
 }
+
+func Test_servicePortChainNameBase(t *testing.T) {
+	testCases := []struct {
+		name     string
+		spn      proxy.ServicePortName
+		protocol string
+		expected string
+	}{
+		{
+			name: "simple",
+			spn: proxy.ServicePortName{
+				NamespacedName: types.NamespacedName{
+					Namespace: "testing",
+					Name:      "service",
+				},
+				Port: "http",
+			},
+			protocol: "tcp",
+			expected: "P4ZYZVCF-testing/service/tcp/http",
+		},
+		{
+			name: "different port, different hash",
+			spn: proxy.ServicePortName{
+				NamespacedName: types.NamespacedName{
+					Namespace: "testing",
+					Name:      "service",
+				},
+				Port: "https",
+			},
+			protocol: "tcp",
+			expected: "LZBRENCP-testing/service/tcp/https",
+		},
+		{
+			name: "max length",
+			spn: proxy.ServicePortName{
+				NamespacedName: types.NamespacedName{
+					Namespace: "very-long-namespace-name-abcdefghijklmnopqrstuvwxyz0123456789xx",
+					Name:      "very-long-service-name-why-would-you-even-do-this-i-mean-really",
+				},
+				Port: "port-443-providing-the-hypertext-transmission-protocol-with-tls",
+			},
+			protocol: "sctp",
+			expected: "KR6NACJP-very-long-namespace-name-abcdefghijklmnopqrstuvwxyz0123456789xx/very-long-service-name-why-would-you-even-do-this-i-mean-really/sctp/port-443-providing-the-hypertext-transmission-protocol-with-tls",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			name := servicePortChainNameBase(&tc.spn, tc.protocol)
+			if name != tc.expected {
+				t.Errorf("expected %q, got %q", tc.expected, name)
+			}
+		})
+	}
+}
+
+func Test_servicePortEndpointChainNameBase(t *testing.T) {
+	testCases := []struct {
+		name     string
+		spn      proxy.ServicePortName
+		protocol string
+		endpoint string
+		expected string
+	}{
+		{
+			name: "simple",
+			spn: proxy.ServicePortName{
+				NamespacedName: types.NamespacedName{
+					Namespace: "testing",
+					Name:      "service",
+				},
+				Port: "http",
+			},
+			protocol: "tcp",
+			endpoint: "10.180.0.1:80",
+			expected: "JO2XBXZR-testing/service/tcp/http__10.180.0.1/80",
+		},
+		{
+			name: "different endpoint, different hash",
+			spn: proxy.ServicePortName{
+				NamespacedName: types.NamespacedName{
+					Namespace: "testing",
+					Name:      "service",
+				},
+				Port: "http",
+			},
+			protocol: "tcp",
+			endpoint: "10.180.0.2:80",
+			expected: "5S6H3H22-testing/service/tcp/http__10.180.0.2/80",
+		},
+		{
+			name: "ipv6",
+			spn: proxy.ServicePortName{
+				NamespacedName: types.NamespacedName{
+					Namespace: "testing",
+					Name:      "service",
+				},
+				Port: "http",
+			},
+			protocol: "tcp",
+			endpoint: "[fd80:abcd:12::a1b2:c3d4:e5f6:9999]:80",
+			expected: "U7E2ET36-testing/service/tcp/http__fd80.abcd.12..a1b2.c3d4.e5f6.9999/80",
+		},
+		{
+			name: "max length without truncation",
+			spn: proxy.ServicePortName{
+				NamespacedName: types.NamespacedName{
+					Namespace: "very-long-namespace-name-abcdefghijklmnopqrstuvwxyz0123456789xx",
+					Name:      "very-long-service-name-why-would-you-even-do-this-i-mean-really",
+				},
+				Port: "port-443-providing-the-hypertext-transmission-protocol-with-tls",
+			},
+			protocol: "sctp",
+			endpoint: "[1234:5678:9abc:def0::abc:1234]:443",
+			expected: "5YS7AFEA-very-long-namespace-name-abcdefghijklmnopqrstuvwxyz0123456789xx/very-long-service-name-why-would-you-even-do-this-i-mean-really/sctp/port-443-providing-the-hypertext-transmission-protocol-with-tls__1234.5678.9abc.def0..abc.1234/443",
+		},
+		{
+			name: "truncated, 1",
+			spn: proxy.ServicePortName{
+				NamespacedName: types.NamespacedName{
+					Namespace: "very-long-namespace-name-abcdefghijklmnopqrstuvwxyz0123456789xx",
+					Name:      "very-long-service-name-why-would-you-even-do-this-i-mean-really",
+				},
+				Port: "port-443-providing-the-hypertext-transmission-protocol-with-tls",
+			},
+			protocol: "sctp",
+			endpoint: "[1234:5678:9abc:def0::abcd:1234:5678]:443",
+			expected: "CI6C53Q3-very-long-namespace-name-abcdefghijklmnopqrstuvwxyz0123456789xx/very-long-service-name-why-would-you-even-do-this-i-mean-really/sctp/port-443-providing-the-hypertext-transmission-protocol-with-tls__1234.5678.9abc.def0..abcd.1234...",
+		},
+		{
+			name: "truncated, 2 (different IP, which is not visible in the result)",
+			spn: proxy.ServicePortName{
+				NamespacedName: types.NamespacedName{
+					Namespace: "very-long-namespace-name-abcdefghijklmnopqrstuvwxyz0123456789xx",
+					Name:      "very-long-service-name-why-would-you-even-do-this-i-mean-really",
+				},
+				Port: "port-443-providing-the-hypertext-transmission-protocol-with-tls",
+			},
+			protocol: "sctp",
+			endpoint: "[1234:5678:9abc:def0::abcd:1234:8765]:443",
+			expected: "2FLXFK6X-very-long-namespace-name-abcdefghijklmnopqrstuvwxyz0123456789xx/very-long-service-name-why-would-you-even-do-this-i-mean-really/sctp/port-443-providing-the-hypertext-transmission-protocol-with-tls__1234.5678.9abc.def0..abcd.1234...",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			name := servicePortEndpointChainNameBase(&tc.spn, tc.protocol, tc.endpoint)
+			if name != tc.expected {
+				t.Errorf("expected %q, got %q", tc.expected, name)
+			}
+		})
+	}
+}