forked from kubernetes/kubernetes
-
Notifications
You must be signed in to change notification settings - Fork 0
/
proxier.go
848 lines (764 loc) · 29.7 KB
/
proxier.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
/*
Copyright 2015 The Kubernetes Authors All rights reserved.
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 iptables
//
// NOTE: this needs to be tested in e2e since it uses iptables for everything.
//
import (
"bytes"
"crypto/sha256"
"encoding/base32"
"fmt"
"net"
"reflect"
"strconv"
"strings"
"sync"
"time"
"github.com/coreos/go-semver/semver"
"github.com/davecgh/go-spew/spew"
"github.com/golang/glog"
"k8s.io/kubernetes/pkg/api"
"k8s.io/kubernetes/pkg/proxy"
"k8s.io/kubernetes/pkg/types"
utilexec "k8s.io/kubernetes/pkg/util/exec"
utiliptables "k8s.io/kubernetes/pkg/util/iptables"
"k8s.io/kubernetes/pkg/util/slice"
utilsysctl "k8s.io/kubernetes/pkg/util/sysctl"
)
// iptablesMinVersion is the minimum version of iptables for which we will use the Proxier
// from this package instead of the userspace Proxier. While most of the
// features we need were available earlier, the '-C' flag was added more
// recently. We use that indirectly in Ensure* functions, and if we don't
// have it, we have to be extra careful about the exact args we feed in being
// the same as the args we read back (iptables itself normalizes some args).
// This is the "new" Proxier, so we require "new" versions of tools.
const iptablesMinVersion = utiliptables.MinCheckVersion
// the services chain
const iptablesServicesChain utiliptables.Chain = "KUBE-SERVICES"
// the nodeports chain
const iptablesNodePortsChain utiliptables.Chain = "KUBE-NODEPORTS"
// the mark we apply to traffic needing SNAT
const iptablesMasqueradeMark = "0x4d415351"
// ShouldUseIptablesProxier returns true if we should use the iptables Proxier
// instead of the "classic" userspace Proxier. This is determined by checking
// the iptables version and for the existence of kernel features. It may return
// an error if it fails to get the iptables version without error, in which
// case it will also return false.
func ShouldUseIptablesProxier() (bool, error) {
exec := utilexec.New()
minVersion, err := semver.NewVersion(iptablesMinVersion)
if err != nil {
return false, err
}
// returns "X.X.X", err
versionString, err := utiliptables.GetIptablesVersionString(exec)
if err != nil {
return false, err
}
version, err := semver.NewVersion(versionString)
if err != nil {
return false, err
}
if version.LessThan(*minVersion) {
return false, nil
}
// Check for the required sysctls. We don't care about the value, just
// that it exists. If this Proxier is chosen, we'll iniialize it as we
// need.
_, err = utilsysctl.GetSysctl(sysctlRouteLocalnet)
if err != nil {
return false, err
}
return true, nil
}
const sysctlRouteLocalnet = "net/ipv4/conf/all/route_localnet"
const sysctlBridgeCallIptables = "net/bridge/bridge-nf-call-iptables"
// internal struct for string service information
type serviceInfo struct {
clusterIP net.IP
port int
protocol api.Protocol
nodePort int
loadBalancerStatus api.LoadBalancerStatus
sessionAffinityType api.ServiceAffinity
stickyMaxAgeSeconds int
// Deprecated, but required for back-compat (including e2e)
externalIPs []string
}
// returns a new serviceInfo struct
func newServiceInfo(service proxy.ServicePortName) *serviceInfo {
return &serviceInfo{
sessionAffinityType: api.ServiceAffinityNone, // default
stickyMaxAgeSeconds: 180, // TODO: paramaterize this in the API.
}
}
// Proxier is an iptables based proxy for connections between a localhost:lport
// and services that provide the actual backends.
type Proxier struct {
mu sync.Mutex // protects the following fields
serviceMap map[proxy.ServicePortName]*serviceInfo
endpointsMap map[proxy.ServicePortName][]string
portsMap map[localPort]closeable
haveReceivedServiceUpdate bool // true once we've seen an OnServiceUpdate event
haveReceivedEndpointsUpdate bool // true once we've seen an OnEndpointsUpdate event
// These are effectively const and do not need the mutex to be held.
syncPeriod time.Duration
iptables utiliptables.Interface
masqueradeAll bool
}
type localPort struct {
desc string
ip string
port int
protocol string
}
func (lp *localPort) String() string {
return fmt.Sprintf("%q (%s:%d/%s)", lp.desc, lp.ip, lp.port, lp.protocol)
}
type closeable interface {
Close() error
}
// Proxier implements ProxyProvider
var _ proxy.ProxyProvider = &Proxier{}
// NewProxier returns a new Proxier given an iptables Interface instance.
// Because of the iptables logic, it is assumed that there is only a single Proxier active on a machine.
// An error will be returned if iptables fails to update or acquire the initial lock.
// Once a proxier is created, it will keep iptables up to date in the background and
// will not terminate if a particular iptables call fails.
func NewProxier(ipt utiliptables.Interface, exec utilexec.Interface, syncPeriod time.Duration, masqueradeAll bool) (*Proxier, error) {
// Set the route_localnet sysctl we need for
if err := utilsysctl.SetSysctl(sysctlRouteLocalnet, 1); err != nil {
return nil, fmt.Errorf("can't set sysctl %s: %v", sysctlRouteLocalnet, err)
}
// Load the module. It's OK if this fails (e.g. the module is not present)
// because we'll catch the error on the sysctl, which is what we actually
// care about.
exec.Command("modprobe", "br-netfilter").CombinedOutput()
if err := utilsysctl.SetSysctl(sysctlBridgeCallIptables, 1); err != nil {
glog.Warningf("can't set sysctl %s: %v", sysctlBridgeCallIptables, err)
}
return &Proxier{
serviceMap: make(map[proxy.ServicePortName]*serviceInfo),
endpointsMap: make(map[proxy.ServicePortName][]string),
portsMap: make(map[localPort]closeable),
syncPeriod: syncPeriod,
iptables: ipt,
masqueradeAll: masqueradeAll,
}, nil
}
// CleanupLeftovers removes all iptables rules and chains created by the Proxier
// It returns true if an error was encountered. Errors are logged.
func CleanupLeftovers(ipt utiliptables.Interface) (encounteredError bool) {
//TODO: actually tear down all rules and chains.
args := []string{"-j", "KUBE-SERVICES"}
if err := ipt.DeleteRule(utiliptables.TableNAT, utiliptables.ChainOutput, args...); err != nil {
glog.Errorf("Error removing pure-iptables proxy rule: %v", err)
encounteredError = true
}
if err := ipt.DeleteRule(utiliptables.TableNAT, utiliptables.ChainPrerouting, args...); err != nil {
glog.Errorf("Error removing pure-iptables proxy rule: %v", err)
encounteredError = true
}
return encounteredError
}
func (proxier *Proxier) sameConfig(info *serviceInfo, service *api.Service, port *api.ServicePort) bool {
if info.protocol != port.Protocol || info.port != port.Port || info.nodePort != port.NodePort {
return false
}
if !info.clusterIP.Equal(net.ParseIP(service.Spec.ClusterIP)) {
return false
}
if !ipsEqual(info.externalIPs, service.Spec.ExternalIPs) {
return false
}
if !api.LoadBalancerStatusEqual(&info.loadBalancerStatus, &service.Status.LoadBalancer) {
return false
}
if info.sessionAffinityType != service.Spec.SessionAffinity {
return false
}
return true
}
func ipsEqual(lhs, rhs []string) bool {
if len(lhs) != len(rhs) {
return false
}
for i := range lhs {
if lhs[i] != rhs[i] {
return false
}
}
return true
}
// Sync is called to immediately synchronize the proxier state to iptables
func (proxier *Proxier) Sync() {
proxier.mu.Lock()
defer proxier.mu.Unlock()
proxier.syncProxyRules()
}
// SyncLoop runs periodic work. This is expected to run as a goroutine or as the main loop of the app. It does not return.
func (proxier *Proxier) SyncLoop() {
t := time.NewTicker(proxier.syncPeriod)
defer t.Stop()
for {
<-t.C
glog.V(6).Infof("Periodic sync")
proxier.Sync()
}
}
// OnServiceUpdate tracks the active set of service proxies.
// They will be synchronized using syncProxyRules()
func (proxier *Proxier) OnServiceUpdate(allServices []api.Service) {
proxier.mu.Lock()
defer proxier.mu.Unlock()
proxier.haveReceivedServiceUpdate = true
activeServices := make(map[proxy.ServicePortName]bool) // use a map as a set
for i := range allServices {
service := &allServices[i]
svcName := types.NamespacedName{
Namespace: service.Namespace,
Name: service.Name,
}
// if ClusterIP is "None" or empty, skip proxying
if !api.IsServiceIPSet(service) {
glog.V(3).Infof("Skipping service %s due to clusterIP = %q", svcName, service.Spec.ClusterIP)
continue
}
for i := range service.Spec.Ports {
servicePort := &service.Spec.Ports[i]
serviceName := proxy.ServicePortName{
NamespacedName: svcName,
Port: servicePort.Name,
}
activeServices[serviceName] = true
info, exists := proxier.serviceMap[serviceName]
if exists && proxier.sameConfig(info, service, servicePort) {
// Nothing changed.
continue
}
if exists {
// Something changed.
glog.V(3).Infof("Something changed for service %q: removing it", serviceName)
delete(proxier.serviceMap, serviceName)
}
serviceIP := net.ParseIP(service.Spec.ClusterIP)
glog.V(1).Infof("Adding new service %q at %s:%d/%s", serviceName, serviceIP, servicePort.Port, servicePort.Protocol)
info = newServiceInfo(serviceName)
info.clusterIP = serviceIP
info.port = servicePort.Port
info.protocol = servicePort.Protocol
info.nodePort = servicePort.NodePort
info.externalIPs = service.Spec.ExternalIPs
// Deep-copy in case the service instance changes
info.loadBalancerStatus = *api.LoadBalancerStatusDeepCopy(&service.Status.LoadBalancer)
info.sessionAffinityType = service.Spec.SessionAffinity
proxier.serviceMap[serviceName] = info
glog.V(4).Infof("added serviceInfo(%s): %s", serviceName, spew.Sdump(info))
}
}
// Remove services missing from the update.
for name := range proxier.serviceMap {
if !activeServices[name] {
glog.V(1).Infof("Removing service %q", name)
delete(proxier.serviceMap, name)
}
}
proxier.syncProxyRules()
}
// OnEndpointsUpdate takes in a slice of updated endpoints.
func (proxier *Proxier) OnEndpointsUpdate(allEndpoints []api.Endpoints) {
proxier.mu.Lock()
defer proxier.mu.Unlock()
proxier.haveReceivedEndpointsUpdate = true
activeEndpoints := make(map[proxy.ServicePortName]bool) // use a map as a set
// Update endpoints for services.
for i := range allEndpoints {
svcEndpoints := &allEndpoints[i]
// We need to build a map of portname -> all ip:ports for that
// portname. Explode Endpoints.Subsets[*] into this structure.
portsToEndpoints := map[string][]hostPortPair{}
for i := range svcEndpoints.Subsets {
ss := &svcEndpoints.Subsets[i]
for i := range ss.Ports {
port := &ss.Ports[i]
for i := range ss.Addresses {
addr := &ss.Addresses[i]
portsToEndpoints[port.Name] = append(portsToEndpoints[port.Name], hostPortPair{addr.IP, port.Port})
}
}
}
for portname := range portsToEndpoints {
svcPort := proxy.ServicePortName{NamespacedName: types.NamespacedName{Namespace: svcEndpoints.Namespace, Name: svcEndpoints.Name}, Port: portname}
curEndpoints := proxier.endpointsMap[svcPort]
newEndpoints := flattenValidEndpoints(portsToEndpoints[portname])
if len(curEndpoints) != len(newEndpoints) || !slicesEquiv(slice.CopyStrings(curEndpoints), newEndpoints) {
glog.V(1).Infof("Setting endpoints for %q to %+v", svcPort, newEndpoints)
proxier.endpointsMap[svcPort] = newEndpoints
}
activeEndpoints[svcPort] = true
}
}
// Remove endpoints missing from the update.
for name := range proxier.endpointsMap {
if !activeEndpoints[name] {
glog.V(2).Infof("Removing endpoints for %q", name)
delete(proxier.endpointsMap, name)
}
}
proxier.syncProxyRules()
}
// used in OnEndpointsUpdate
type hostPortPair struct {
host string
port int
}
func isValidEndpoint(hpp *hostPortPair) bool {
return hpp.host != "" && hpp.port > 0
}
// Tests whether two slices are equivalent. This sorts both slices in-place.
func slicesEquiv(lhs, rhs []string) bool {
if len(lhs) != len(rhs) {
return false
}
if reflect.DeepEqual(slice.SortStrings(lhs), slice.SortStrings(rhs)) {
return true
}
return false
}
func flattenValidEndpoints(endpoints []hostPortPair) []string {
// Convert Endpoint objects into strings for easier use later.
var result []string
for i := range endpoints {
hpp := &endpoints[i]
if isValidEndpoint(hpp) {
result = append(result, net.JoinHostPort(hpp.host, strconv.Itoa(hpp.port)))
} else {
glog.Warningf("got invalid endpoint: %+v", *hpp)
}
}
return result
}
// servicePortChainName takes the ServicePortName for a service and
// returns the associated iptables chain. This is computed by hashing (sha256)
// then encoding to base32 and truncating with the prefix "KUBE-SVC-". We do
// this because Iptables Chain Names must be <= 28 chars long, and the longer
// they are the harder they are to read.
func servicePortChainName(s proxy.ServicePortName, protocol string) utiliptables.Chain {
hash := sha256.Sum256([]byte(s.String() + protocol))
encoded := base32.StdEncoding.EncodeToString(hash[:])
return utiliptables.Chain("KUBE-SVC-" + encoded[:16])
}
// This is the same as servicePortChainName but with the endpoint included.
func servicePortEndpointChainName(s proxy.ServicePortName, protocol string, endpoint string) utiliptables.Chain {
hash := sha256.Sum256([]byte(s.String() + protocol + endpoint))
encoded := base32.StdEncoding.EncodeToString(hash[:])
return utiliptables.Chain("KUBE-SEP-" + encoded[:16])
}
// This is where all of the iptables-save/restore calls happen.
// The only other iptables rules are those that are setup in iptablesInit()
// assumes proxier.mu is held
func (proxier *Proxier) syncProxyRules() {
// don't sync rules till we've received services and endpoints
if !proxier.haveReceivedEndpointsUpdate || !proxier.haveReceivedServiceUpdate {
glog.V(2).Info("Not syncing iptables until Services and Endpoints have been received from master")
return
}
glog.V(3).Infof("Syncing iptables rules")
// Ensure main chains and rules are installed.
inputChains := []utiliptables.Chain{utiliptables.ChainOutput, utiliptables.ChainPrerouting}
// Link the services chain.
for _, chain := range inputChains {
if _, err := proxier.iptables.EnsureChain(utiliptables.TableNAT, iptablesServicesChain); err != nil {
glog.Errorf("Failed to ensure that chain %s exists: %v", iptablesServicesChain, err)
return
}
comment := "kubernetes service portals"
args := []string{"-m", "comment", "--comment", comment, "-j", string(iptablesServicesChain)}
if _, err := proxier.iptables.EnsureRule(utiliptables.Prepend, utiliptables.TableNAT, chain, args...); err != nil {
glog.Errorf("Failed to ensure that chain %s jumps to %s: %v", chain, iptablesServicesChain, err)
return
}
}
// Link the output rules.
{
comment := "kubernetes service traffic requiring SNAT"
args := []string{"-m", "comment", "--comment", comment, "-m", "mark", "--mark", iptablesMasqueradeMark, "-j", "MASQUERADE"}
if _, err := proxier.iptables.EnsureRule(utiliptables.Append, utiliptables.TableNAT, utiliptables.ChainPostrouting, args...); err != nil {
glog.Errorf("Failed to ensure that chain %s obeys MASQUERADE mark: %v", utiliptables.ChainPostrouting, err)
return
}
}
// Get iptables-save output so we can check for existing chains and rules.
// This will be a map of chain name to chain with rules as stored in iptables-save/iptables-restore
existingChains := make(map[utiliptables.Chain]string)
iptablesSaveRaw, err := proxier.iptables.Save(utiliptables.TableNAT)
if err != nil { // if we failed to get any rules
glog.Errorf("Failed to execute iptables-save, syncing all rules. %s", err.Error())
} else { // otherwise parse the output
existingChains = getChainLines(utiliptables.TableNAT, iptablesSaveRaw)
}
chainsLines := bytes.NewBuffer(nil)
rulesLines := bytes.NewBuffer(nil)
// Write table header.
writeLine(chainsLines, "*nat")
// Make sure we keep stats for the top-level chains, if they existed
// (which they should have because we created them above).
if chain, ok := existingChains[iptablesServicesChain]; ok {
writeLine(chainsLines, chain)
} else {
writeLine(chainsLines, makeChainLine(iptablesServicesChain))
}
if chain, ok := existingChains[iptablesNodePortsChain]; ok {
writeLine(chainsLines, chain)
} else {
writeLine(chainsLines, makeChainLine(iptablesNodePortsChain))
}
// Accumulate chains to keep.
activeChains := map[utiliptables.Chain]bool{} // use a map as a set
// Accumulate new local ports that we have opened.
newLocalPorts := map[localPort]closeable{}
// Build rules for each service.
for svcName, svcInfo := range proxier.serviceMap {
protocol := strings.ToLower(string(svcInfo.protocol))
// Create the per-service chain, retaining counters if possible.
svcChain := servicePortChainName(svcName, protocol)
if chain, ok := existingChains[svcChain]; ok {
writeLine(chainsLines, chain)
} else {
writeLine(chainsLines, makeChainLine(svcChain))
}
activeChains[svcChain] = true
// Capture the clusterIP.
args := []string{
"-A", string(iptablesServicesChain),
"-m", "comment", "--comment", fmt.Sprintf("\"%s cluster IP\"", svcName.String()),
"-m", protocol, "-p", protocol,
"-d", fmt.Sprintf("%s/32", svcInfo.clusterIP.String()),
"--dport", fmt.Sprintf("%d", svcInfo.port),
}
if proxier.masqueradeAll {
writeLine(rulesLines, append(args,
"-j", "MARK", "--set-xmark", fmt.Sprintf("%s/0xffffffff", iptablesMasqueradeMark))...)
}
writeLine(rulesLines, append(args,
"-j", string(svcChain))...)
// Capture externalIPs.
for _, externalIP := range svcInfo.externalIPs {
// If the "external" IP happens to be an IP that is local to this
// machine, hold the local port open so no other process can open it
// (because the socket might open but it would never work).
if local, err := isLocalIP(externalIP); err != nil {
glog.Errorf("can't determine if IP is local, assuming not: %v", err)
} else if local {
lp := localPort{
desc: "externalIP for " + svcName.String(),
ip: externalIP,
port: svcInfo.port,
protocol: protocol,
}
if proxier.portsMap[lp] != nil {
newLocalPorts[lp] = proxier.portsMap[lp]
} else {
socket, err := openLocalPort(&lp)
if err != nil {
glog.Errorf("can't open %s, skipping this externalIP: %v", lp.String(), err)
continue
}
newLocalPorts[lp] = socket
}
} // We're holding the port, so it's OK to install iptables rules.
args := []string{
"-A", string(iptablesServicesChain),
"-m", "comment", "--comment", fmt.Sprintf("\"%s external IP\"", svcName.String()),
"-m", protocol, "-p", protocol,
"-d", fmt.Sprintf("%s/32", externalIP),
"--dport", fmt.Sprintf("%d", svcInfo.port),
}
// We have to SNAT packets to external IPs.
writeLine(rulesLines, append(args,
"-j", "MARK", "--set-xmark", fmt.Sprintf("%s/0xffffffff", iptablesMasqueradeMark))...)
// Allow traffic for external IPs that does not come from a bridge (i.e. not from a container)
// nor from a local process to be forwarded to the service.
// This rule roughly translates to "all traffic from off-machine".
// This is imperfect in the face of network plugins that might not use a bridge, but we can revisit that later.
externalTrafficOnlyArgs := append(args,
"-m", "physdev", "!", "--physdev-is-in",
"-m", "addrtype", "!", "--src-type", "LOCAL")
writeLine(rulesLines, append(externalTrafficOnlyArgs,
"-j", string(svcChain))...)
dstLocalOnlyArgs := append(args, "-m", "addrtype", "--dst-type", "LOCAL")
// Allow traffic bound for external IPs that happen to be recognized as local IPs to stay local.
// This covers cases like GCE load-balancers which get added to the local routing table.
writeLine(rulesLines, append(dstLocalOnlyArgs,
"-j", string(svcChain))...)
}
// Capture load-balancer ingress.
for _, ingress := range svcInfo.loadBalancerStatus.Ingress {
if ingress.IP != "" {
args := []string{
"-A", string(iptablesServicesChain),
"-m", "comment", "--comment", fmt.Sprintf("\"%s loadbalancer IP\"", svcName.String()),
"-m", protocol, "-p", protocol,
"-d", fmt.Sprintf("%s/32", ingress.IP),
"--dport", fmt.Sprintf("%d", svcInfo.port),
}
// We have to SNAT packets from external IPs.
writeLine(rulesLines, append(args,
"-j", "MARK", "--set-xmark", fmt.Sprintf("%s/0xffffffff", iptablesMasqueradeMark))...)
writeLine(rulesLines, append(args,
"-j", string(svcChain))...)
}
}
// Capture nodeports. If we had more than 2 rules it might be
// worthwhile to make a new per-service chain for nodeport rules, but
// with just 2 rules it ends up being a waste and a cognitive burden.
if svcInfo.nodePort != 0 {
// Hold the local port open so no other process can open it
// (because the socket might open but it would never work).
lp := localPort{
desc: "nodePort for " + svcName.String(),
ip: "",
port: svcInfo.nodePort,
protocol: protocol,
}
if proxier.portsMap[lp] != nil {
newLocalPorts[lp] = proxier.portsMap[lp]
} else {
socket, err := openLocalPort(&lp)
if err != nil {
glog.Errorf("can't open %s, skipping this nodePort: %v", lp.String(), err)
continue
}
newLocalPorts[lp] = socket
} // We're holding the port, so it's OK to install iptables rules.
// Nodeports need SNAT.
writeLine(rulesLines,
"-A", string(iptablesNodePortsChain),
"-m", "comment", "--comment", svcName.String(),
"-m", protocol, "-p", protocol,
"--dport", fmt.Sprintf("%d", svcInfo.nodePort),
"-j", "MARK", "--set-xmark", fmt.Sprintf("%s/0xffffffff", iptablesMasqueradeMark))
// Jump to the service chain.
writeLine(rulesLines,
"-A", string(iptablesNodePortsChain),
"-m", "comment", "--comment", svcName.String(),
"-m", protocol, "-p", protocol,
"--dport", fmt.Sprintf("%d", svcInfo.nodePort),
"-j", string(svcChain))
}
// Generate the per-endpoint chains. We do this in multiple passes so we
// can group rules together.
endpoints := make([]string, 0)
endpointChains := make([]utiliptables.Chain, 0)
for _, ep := range proxier.endpointsMap[svcName] {
endpoints = append(endpoints, ep)
endpointChain := servicePortEndpointChainName(svcName, protocol, ep)
endpointChains = append(endpointChains, endpointChain)
// Create the endpoint chain, retaining counters if possible.
if chain, ok := existingChains[utiliptables.Chain(endpointChain)]; ok {
writeLine(chainsLines, chain)
} else {
writeLine(chainsLines, makeChainLine(endpointChain))
}
activeChains[endpointChain] = true
}
// First write session affinity rules, if applicable.
if svcInfo.sessionAffinityType == api.ServiceAffinityClientIP {
for _, endpointChain := range endpointChains {
writeLine(rulesLines,
"-A", string(svcChain),
"-m", "comment", "--comment", svcName.String(),
"-m", "recent", "--name", string(endpointChain),
"--rcheck", "--seconds", fmt.Sprintf("%d", svcInfo.stickyMaxAgeSeconds), "--reap",
"-j", string(endpointChain))
}
}
// Now write loadbalancing & DNAT rules.
n := len(endpointChains)
for i, endpointChain := range endpointChains {
// Balancing rules in the per-service chain.
args := []string{
"-A", string(svcChain),
"-m", "comment", "--comment", svcName.String(),
}
if i < (n - 1) {
// Each rule is a probabilistic match.
args = append(args,
"-m", "statistic",
"--mode", "random",
"--probability", fmt.Sprintf("%0.5f", 1.0/float64(n-i)))
}
// The final (or only if n == 1) rule is a guaranteed match.
args = append(args, "-j", string(endpointChain))
writeLine(rulesLines, args...)
// Rules in the per-endpoint chain.
args = []string{
"-A", string(endpointChain),
"-m", "comment", "--comment", svcName.String(),
}
// Handle traffic that loops back to the originator with SNAT.
// Technically we only need to do this if the endpoint is on this
// host, but we don't have that information, so we just do this for
// all endpoints.
// TODO: if we grow logic to get this node's pod CIDR, we can use it.
writeLine(rulesLines, append(args,
"-s", fmt.Sprintf("%s/32", strings.Split(endpoints[i], ":")[0]),
"-j", "MARK", "--set-xmark", fmt.Sprintf("%s/0xffffffff", iptablesMasqueradeMark))...)
// Update client-affinity lists.
if svcInfo.sessionAffinityType == api.ServiceAffinityClientIP {
args = append(args, "-m", "recent", "--name", string(endpointChain), "--set")
}
// DNAT to final destination.
args = append(args,
"-m", protocol, "-p", protocol,
"-j", "DNAT", "--to-destination", endpoints[i])
writeLine(rulesLines, args...)
}
}
// Delete chains no longer in use.
for chain := range existingChains {
if !activeChains[chain] {
chainString := string(chain)
if !strings.HasPrefix(chainString, "KUBE-SVC-") && !strings.HasPrefix(chainString, "KUBE-SEP-") {
// 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.
writeLine(chainsLines, existingChains[chain])
writeLine(rulesLines, "-X", chainString)
}
}
// Finally, tail-call to the nodeports chain. This needs to be after all
// other service portal rules.
writeLine(rulesLines,
"-A", string(iptablesServicesChain),
"-m", "comment", "--comment", "\"kubernetes service nodeports; NOTE: this must be the last rule in this chain\"",
"-m", "addrtype", "--dst-type", "LOCAL",
"-j", string(iptablesNodePortsChain))
// Write the end-of-table marker.
writeLine(rulesLines, "COMMIT")
// Sync rules.
// NOTE: NoFlushTables is used so we don't flush non-kubernetes chains in the table.
lines := append(chainsLines.Bytes(), rulesLines.Bytes()...)
glog.V(3).Infof("Syncing rules: %s", lines)
err = proxier.iptables.Restore(utiliptables.TableNAT, lines, utiliptables.NoFlushTables, utiliptables.RestoreCounters)
if err != nil {
glog.Errorf("Failed to sync iptables rules: %v", err)
// Revert new local ports.
for k, v := range newLocalPorts {
glog.Errorf("Closing local port %s", k.String())
v.Close()
}
} else {
// Close old local ports and save new ones.
for k, v := range proxier.portsMap {
if newLocalPorts[k] == nil {
v.Close()
}
}
proxier.portsMap = newLocalPorts
}
}
// Join all words with spaces, terminate with newline and write to buf.
func writeLine(buf *bytes.Buffer, words ...string) {
buf.WriteString(strings.Join(words, " ") + "\n")
}
// return an iptables-save/restore formatted chain line given a Chain
func makeChainLine(chain utiliptables.Chain) string {
return fmt.Sprintf(":%s - [0:0]", chain)
}
// getChainLines parses a table's iptables-save data to find chains in the table.
// It returns a map of iptables.Chain to string where the string is the chain line from the save (with counters etc).
func getChainLines(table utiliptables.Table, save []byte) map[utiliptables.Chain]string {
// get lines
lines := strings.Split(string(save), "\n")
chainsMap := make(map[utiliptables.Chain]string)
tablePrefix := "*" + string(table)
lineNum := 0
// find beginning of table
for ; lineNum < len(lines); lineNum++ {
if strings.HasPrefix(strings.TrimSpace(lines[lineNum]), tablePrefix) {
lineNum++
break
}
}
// parse table lines
for ; lineNum < len(lines); lineNum++ {
line := strings.TrimSpace(lines[lineNum])
if strings.HasPrefix(line, "COMMIT") || strings.HasPrefix(line, "*") {
break
} else if len(line) == 0 || strings.HasPrefix(line, "#") {
continue
} else if strings.HasPrefix(line, ":") && len(line) > 1 {
chain := utiliptables.Chain(strings.SplitN(line[1:], " ", 2)[0])
chainsMap[chain] = lines[lineNum]
}
}
return chainsMap
}
func isLocalIP(ip string) (bool, error) {
addrs, err := net.InterfaceAddrs()
if err != nil {
return false, err
}
for i := range addrs {
intf, _, err := net.ParseCIDR(addrs[i].String())
if err != nil {
return false, err
}
if net.ParseIP(ip).Equal(intf) {
return true, nil
}
}
return false, nil
}
func openLocalPort(lp *localPort) (closeable, error) {
// For ports on node IPs, open the actual port and hold it, even though we
// use iptables to redirect traffic.
// This ensures a) that it's safe to use that port and b) that (a) stays
// true. The risk is that some process on the node (e.g. sshd or kubelet)
// is using a port and we give that same port out to a Service. That would
// be bad because iptables would silently claim the traffic but the process
// would never know.
// NOTE: We should not need to have a real listen()ing socket - bind()
// should be enough, but I can't figure out a way to e2e test without
// it. Tools like 'ss' and 'netstat' do not show sockets that are
// bind()ed but not listen()ed, and at least the default debian netcat
// has no way to avoid about 10 seconds of retries.
var socket closeable
switch lp.protocol {
case "tcp":
listener, err := net.Listen("tcp", net.JoinHostPort(lp.ip, strconv.Itoa(lp.port)))
if err != nil {
return nil, err
}
socket = listener
case "udp":
addr, err := net.ResolveUDPAddr("udp", net.JoinHostPort(lp.ip, strconv.Itoa(lp.port)))
if err != nil {
return nil, err
}
conn, err := net.ListenUDP("udp", addr)
if err != nil {
return nil, err
}
socket = conn
default:
return nil, fmt.Errorf("unknown protocol %q", lp.protocol)
}
glog.V(2).Infof("Opened local port %s", lp.String())
return socket, nil
}