aboutsummaryrefslogtreecommitdiff
path: root/libpod/networking_linux.go
blob: 6f266e5d63187ca389a6f185215c27a9f54196a7 (plain)
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
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
// +build linux

package libpod

import (
	"bytes"
	"crypto/rand"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"syscall"
	"time"

	cnitypes "github.com/containernetworking/cni/pkg/types/current"
	"github.com/containernetworking/plugins/pkg/ns"
	"github.com/containers/podman/v2/libpod/define"
	"github.com/containers/podman/v2/pkg/errorhandling"
	"github.com/containers/podman/v2/pkg/netns"
	"github.com/containers/podman/v2/pkg/rootless"
	"github.com/containers/podman/v2/pkg/rootlessport"
	"github.com/cri-o/ocicni/pkg/ocicni"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	"github.com/vishvananda/netlink"
	"golang.org/x/sys/unix"
)

// Get an OCICNI network config
func (r *Runtime) getPodNetwork(id, name, nsPath string, networks []string, ports []ocicni.PortMapping, staticIP net.IP, staticMAC net.HardwareAddr) ocicni.PodNetwork {
	var networkKey string
	if len(networks) > 0 {
		// This is inconsistent for >1 network, but it's probably the
		// best we can do.
		networkKey = networks[0]
	} else {
		networkKey = r.netPlugin.GetDefaultNetworkName()
	}
	network := ocicni.PodNetwork{
		Name:      name,
		Namespace: name, // TODO is there something else we should put here? We don't know about Kube namespaces
		ID:        id,
		NetNS:     nsPath,
		RuntimeConfig: map[string]ocicni.RuntimeConfig{
			networkKey: {PortMappings: ports},
		},
	}

	// If we have extra networks, add them
	if len(networks) > 0 {
		network.Networks = make([]ocicni.NetAttachment, len(networks))
		for i, netName := range networks {
			network.Networks[i].Name = netName
		}
	}

	if staticIP != nil || staticMAC != nil {
		// For static IP or MAC, we need to populate networks even if
		// it's just the default.
		if len(networks) == 0 {
			// If len(networks) == 0 this is guaranteed to be the
			// default network.
			network.Networks = []ocicni.NetAttachment{{Name: networkKey}}
		}
		var rt ocicni.RuntimeConfig = ocicni.RuntimeConfig{PortMappings: ports}
		if staticIP != nil {
			rt.IP = staticIP.String()
		}
		if staticMAC != nil {
			rt.MAC = staticMAC.String()
		}
		network.RuntimeConfig = map[string]ocicni.RuntimeConfig{
			networkKey: rt,
		}
	}

	return network
}

// Create and configure a new network namespace for a container
func (r *Runtime) configureNetNS(ctr *Container, ctrNS ns.NetNS) ([]*cnitypes.Result, error) {
	var requestedIP net.IP
	if ctr.requestedIP != nil {
		requestedIP = ctr.requestedIP
		// cancel request for a specific IP in case the container is reused later
		ctr.requestedIP = nil
	} else {
		requestedIP = ctr.config.StaticIP
	}

	var requestedMAC net.HardwareAddr
	if ctr.requestedMAC != nil {
		requestedMAC = ctr.requestedMAC
		// cancel request for a specific MAC in case the container is reused later
		ctr.requestedMAC = nil
	} else {
		requestedMAC = ctr.config.StaticMAC
	}

	// If we are in a pod use the pod name for the network, otherwise the container name
	var podName string
	if ctr.PodID() != "" {
		pod, err := r.GetPod(ctr.PodID())
		if err == nil {
			podName = pod.Name()
		}
	}
	if podName == "" {
		podName = ctr.Name()
	}

	podNetwork := r.getPodNetwork(ctr.ID(), podName, ctrNS.Path(), ctr.config.Networks, ctr.config.PortMappings, requestedIP, requestedMAC)

	results, err := r.netPlugin.SetUpPod(podNetwork)
	if err != nil {
		return nil, errors.Wrapf(err, "error configuring network namespace for container %s", ctr.ID())
	}
	defer func() {
		if err != nil {
			if err2 := r.netPlugin.TearDownPod(podNetwork); err2 != nil {
				logrus.Errorf("Error tearing down partially created network namespace for container %s: %v", ctr.ID(), err2)
			}
		}
	}()

	networkStatus := make([]*cnitypes.Result, 0)
	for idx, r := range results {
		logrus.Debugf("[%d] CNI result: %v", idx, r.Result)
		resultCurrent, err := cnitypes.GetResult(r.Result)
		if err != nil {
			return nil, errors.Wrapf(err, "error parsing CNI plugin result %q: %v", r.Result, err)
		}
		networkStatus = append(networkStatus, resultCurrent)
	}

	return networkStatus, nil
}

// Create and configure a new network namespace for a container
func (r *Runtime) createNetNS(ctr *Container) (n ns.NetNS, q []*cnitypes.Result, retErr error) {
	ctrNS, err := netns.NewNS()
	if err != nil {
		return nil, nil, errors.Wrapf(err, "error creating network namespace for container %s", ctr.ID())
	}
	defer func() {
		if retErr != nil {
			if err := netns.UnmountNS(ctrNS); err != nil {
				logrus.Errorf("Error unmounting partially created network namespace for container %s: %v", ctr.ID(), err)
			}
			if err := ctrNS.Close(); err != nil {
				logrus.Errorf("Error closing partially created network namespace for container %s: %v", ctr.ID(), err)
			}
		}
	}()

	logrus.Debugf("Made network namespace at %s for container %s", ctrNS.Path(), ctr.ID())

	networkStatus := []*cnitypes.Result{}
	if !rootless.IsRootless() && !ctr.config.NetMode.IsSlirp4netns() {
		networkStatus, err = r.configureNetNS(ctr, ctrNS)
	}
	return ctrNS, networkStatus, err
}

type slirpFeatures struct {
	HasDisableHostLoopback bool
	HasMTU                 bool
	HasEnableSandbox       bool
	HasEnableSeccomp       bool
	HasCIDR                bool
	HasOutboundAddr        bool
	HasIPv6                bool
}

type slirp4netnsCmdArg struct {
	Proto     string `json:"proto,omitempty"`
	HostAddr  string `json:"host_addr"`
	HostPort  int32  `json:"host_port"`
	GuestAddr string `json:"guest_addr"`
	GuestPort int32  `json:"guest_port"`
}

type slirp4netnsCmd struct {
	Execute string            `json:"execute"`
	Args    slirp4netnsCmdArg `json:"arguments"`
}

func checkSlirpFlags(path string) (*slirpFeatures, error) {
	cmd := exec.Command(path, "--help")
	out, err := cmd.CombinedOutput()
	if err != nil {
		return nil, errors.Wrapf(err, "slirp4netns %q", out)
	}
	return &slirpFeatures{
		HasDisableHostLoopback: strings.Contains(string(out), "--disable-host-loopback"),
		HasMTU:                 strings.Contains(string(out), "--mtu"),
		HasEnableSandbox:       strings.Contains(string(out), "--enable-sandbox"),
		HasEnableSeccomp:       strings.Contains(string(out), "--enable-seccomp"),
		HasCIDR:                strings.Contains(string(out), "--cidr"),
		HasOutboundAddr:        strings.Contains(string(out), "--outbound-addr"),
		HasIPv6:                strings.Contains(string(out), "--enable-ipv6"),
	}, nil
}

// Configure the network namespace for a rootless container
func (r *Runtime) setupRootlessNetNS(ctr *Container) error {
	path := r.config.Engine.NetworkCmdPath

	if path == "" {
		var err error
		path, err = exec.LookPath("slirp4netns")
		if err != nil {
			logrus.Errorf("could not find slirp4netns, the network namespace won't be configured: %v", err)
			return nil
		}
	}

	syncR, syncW, err := os.Pipe()
	if err != nil {
		return errors.Wrapf(err, "failed to open pipe")
	}
	defer errorhandling.CloseQuiet(syncR)
	defer errorhandling.CloseQuiet(syncW)

	havePortMapping := len(ctr.Config().PortMappings) > 0
	logPath := filepath.Join(ctr.runtime.config.Engine.TmpDir, fmt.Sprintf("slirp4netns-%s.log", ctr.config.ID))

	cidr := ""
	isSlirpHostForward := false
	disableHostLoopback := true
	enableIPv6 := false
	outboundAddr := ""
	outboundAddr6 := ""

	if ctr.config.NetworkOptions != nil {
		slirpOptions := ctr.config.NetworkOptions["slirp4netns"]
		for _, o := range slirpOptions {
			parts := strings.Split(o, "=")
			option, value := parts[0], parts[1]

			switch option {
			case "cidr":
				ipv4, _, err := net.ParseCIDR(value)
				if err != nil || ipv4.To4() == nil {
					return errors.Errorf("invalid cidr %q", value)
				}
				cidr = value
			case "port_handler":
				switch value {
				case "slirp4netns":
					isSlirpHostForward = true
				case "rootlesskit":
					isSlirpHostForward = false
				default:
					return errors.Errorf("unknown port_handler for slirp4netns: %q", value)
				}
			case "allow_host_loopback":
				switch value {
				case "true":
					disableHostLoopback = false
				case "false":
					disableHostLoopback = true
				default:
					return errors.Errorf("invalid value of allow_host_loopback for slirp4netns: %q", value)
				}
			case "enable_ipv6":
				switch value {
				case "true":
					enableIPv6 = true
				case "false":
					enableIPv6 = false
				default:
					return errors.Errorf("invalid value of enable_ipv6 for slirp4netns: %q", value)
				}
			case "outbound_addr":
				ipv4 := net.ParseIP(value)
				if ipv4 == nil || ipv4.To4() == nil {
					_, err := net.InterfaceByName(value)
					if err != nil {
						return errors.Errorf("invalid outbound_addr %q", value)
					}
				}
				outboundAddr = value
			case "outbound_addr6":
				ipv6 := net.ParseIP(value)
				if ipv6 == nil || ipv6.To4() != nil {
					_, err := net.InterfaceByName(value)
					if err != nil {
						return errors.Errorf("invalid outbound_addr6: %q", value)
					}
				}
				outboundAddr6 = value
			default:
				return errors.Errorf("unknown option for slirp4netns: %q", o)
			}
		}
	}

	cmdArgs := []string{}
	slirpFeatures, err := checkSlirpFlags(path)
	if err != nil {
		return errors.Wrapf(err, "error checking slirp4netns binary %s: %q", path, err)
	}
	if disableHostLoopback && slirpFeatures.HasDisableHostLoopback {
		cmdArgs = append(cmdArgs, "--disable-host-loopback")
	}
	if slirpFeatures.HasMTU {
		cmdArgs = append(cmdArgs, "--mtu", "65520")
	}
	if slirpFeatures.HasEnableSandbox {
		cmdArgs = append(cmdArgs, "--enable-sandbox")
	}
	if slirpFeatures.HasEnableSeccomp {
		cmdArgs = append(cmdArgs, "--enable-seccomp")
	}

	if cidr != "" {
		if !slirpFeatures.HasCIDR {
			return errors.Errorf("cidr not supported")
		}
		cmdArgs = append(cmdArgs, fmt.Sprintf("--cidr=%s", cidr))
	}

	if enableIPv6 {
		if !slirpFeatures.HasIPv6 {
			return errors.Errorf("enable_ipv6 not supported")
		}
		cmdArgs = append(cmdArgs, "--enable-ipv6")
	}

	if outboundAddr != "" {
		if !slirpFeatures.HasOutboundAddr {
			return errors.Errorf("outbound_addr not supported")
		}
		cmdArgs = append(cmdArgs, fmt.Sprintf("--outbound-addr=%s", outboundAddr))
	}

	if outboundAddr6 != "" {
		if !slirpFeatures.HasOutboundAddr || !slirpFeatures.HasIPv6 {
			return errors.Errorf("outbound_addr6 not supported")
		}
		if !enableIPv6 {
			return errors.Errorf("enable_ipv6=true is required for outbound_addr6")
		}
		cmdArgs = append(cmdArgs, fmt.Sprintf("--outbound-addr6=%s", outboundAddr6))
	}

	var apiSocket string
	if havePortMapping && isSlirpHostForward {
		apiSocket = filepath.Join(ctr.runtime.config.Engine.TmpDir, fmt.Sprintf("%s.net", ctr.config.ID))
		cmdArgs = append(cmdArgs, "--api-socket", apiSocket)
	}

	// the slirp4netns arguments being passed are describes as follows:
	// from the slirp4netns documentation: https://github.com/rootless-containers/slirp4netns
	// -c, --configure Brings up the tap interface
	// -e, --exit-fd=FD specify the FD for terminating slirp4netns
	// -r, --ready-fd=FD specify the FD to write to when the initialization steps are finished
	cmdArgs = append(cmdArgs, "-c", "-e", "3", "-r", "4")
	netnsPath := ""
	if !ctr.config.PostConfigureNetNS {
		ctr.rootlessSlirpSyncR, ctr.rootlessSlirpSyncW, err = os.Pipe()
		if err != nil {
			return errors.Wrapf(err, "failed to create rootless network sync pipe")
		}
		netnsPath = ctr.state.NetNS.Path()
		cmdArgs = append(cmdArgs, "--netns-type=path", netnsPath, "tap0")
	} else {
		defer errorhandling.CloseQuiet(ctr.rootlessSlirpSyncR)
		defer errorhandling.CloseQuiet(ctr.rootlessSlirpSyncW)
		netnsPath = fmt.Sprintf("/proc/%d/ns/net", ctr.state.PID)
		// we don't use --netns-path here (unavailable for slirp4netns < v0.4)
		cmdArgs = append(cmdArgs, fmt.Sprintf("%d", ctr.state.PID), "tap0")
	}

	cmd := exec.Command(path, cmdArgs...)
	logrus.Debugf("slirp4netns command: %s", strings.Join(cmd.Args, " "))
	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setpgid: true,
	}

	// workaround for https://github.com/rootless-containers/slirp4netns/pull/153
	if slirpFeatures.HasEnableSandbox {
		cmd.SysProcAttr.Cloneflags = syscall.CLONE_NEWNS
		cmd.SysProcAttr.Unshareflags = syscall.CLONE_NEWNS
	}

	// Leak one end of the pipe in slirp4netns, the other will be sent to conmon
	cmd.ExtraFiles = append(cmd.ExtraFiles, ctr.rootlessSlirpSyncR, syncW)

	logFile, err := os.Create(logPath)
	if err != nil {
		return errors.Wrapf(err, "failed to open slirp4netns log file %s", logPath)
	}
	defer logFile.Close()
	// Unlink immediately the file so we won't need to worry about cleaning it up later.
	// It is still accessible through the open fd logFile.
	if err := os.Remove(logPath); err != nil {
		return errors.Wrapf(err, "delete file %s", logPath)
	}
	cmd.Stdout = logFile
	cmd.Stderr = logFile
	if err := cmd.Start(); err != nil {
		return errors.Wrapf(err, "failed to start slirp4netns process")
	}
	defer func() {
		if err := cmd.Process.Release(); err != nil {
			logrus.Errorf("unable to release command process: %q", err)
		}
	}()

	if err := waitForSync(syncR, cmd, logFile, 1*time.Second); err != nil {
		return err
	}

	if havePortMapping {
		if isSlirpHostForward {
			return r.setupRootlessPortMappingViaSlirp(ctr, cmd, apiSocket)
		} else {
			return r.setupRootlessPortMappingViaRLK(ctr, netnsPath)
		}
	}
	return nil
}

func waitForSync(syncR *os.File, cmd *exec.Cmd, logFile io.ReadSeeker, timeout time.Duration) error {
	prog := filepath.Base(cmd.Path)
	if len(cmd.Args) > 0 {
		prog = cmd.Args[0]
	}
	b := make([]byte, 16)
	for {
		if err := syncR.SetDeadline(time.Now().Add(timeout)); err != nil {
			return errors.Wrapf(err, "error setting %s pipe timeout", prog)
		}
		// FIXME: return err as soon as proc exits, without waiting for timeout
		if _, err := syncR.Read(b); err == nil {
			break
		} else {
			if os.IsTimeout(err) {
				// Check if the process is still running.
				var status syscall.WaitStatus
				pid, err := syscall.Wait4(cmd.Process.Pid, &status, syscall.WNOHANG, nil)
				if err != nil {
					return errors.Wrapf(err, "failed to read %s process status", prog)
				}
				if pid != cmd.Process.Pid {
					continue
				}
				if status.Exited() {
					// Seek at the beginning of the file and read all its content
					if _, err := logFile.Seek(0, 0); err != nil {
						logrus.Errorf("could not seek log file: %q", err)
					}
					logContent, err := ioutil.ReadAll(logFile)
					if err != nil {
						return errors.Wrapf(err, "%s failed", prog)
					}
					return errors.Errorf("%s failed: %q", prog, logContent)
				}
				if status.Signaled() {
					return errors.Errorf("%s killed by signal", prog)
				}
				continue
			}
			return errors.Wrapf(err, "failed to read from %s sync pipe", prog)
		}
	}
	return nil
}

func (r *Runtime) setupRootlessPortMappingViaRLK(ctr *Container, netnsPath string) error {
	syncR, syncW, err := os.Pipe()
	if err != nil {
		return errors.Wrapf(err, "failed to open pipe")
	}
	defer errorhandling.CloseQuiet(syncR)
	defer errorhandling.CloseQuiet(syncW)

	logPath := filepath.Join(ctr.runtime.config.Engine.TmpDir, fmt.Sprintf("rootlessport-%s.log", ctr.config.ID))
	logFile, err := os.Create(logPath)
	if err != nil {
		return errors.Wrapf(err, "failed to open rootlessport log file %s", logPath)
	}
	defer logFile.Close()
	// Unlink immediately the file so we won't need to worry about cleaning it up later.
	// It is still accessible through the open fd logFile.
	if err := os.Remove(logPath); err != nil {
		return errors.Wrapf(err, "delete file %s", logPath)
	}

	if !ctr.config.PostConfigureNetNS {
		ctr.rootlessPortSyncR, ctr.rootlessPortSyncW, err = os.Pipe()
		if err != nil {
			return errors.Wrapf(err, "failed to create rootless port sync pipe")
		}
	}

	cfg := rootlessport.Config{
		Mappings:  ctr.config.PortMappings,
		NetNSPath: netnsPath,
		ExitFD:    3,
		ReadyFD:   4,
		TmpDir:    ctr.runtime.config.Engine.TmpDir,
	}
	cfgJSON, err := json.Marshal(cfg)
	if err != nil {
		return err
	}
	cfgR := bytes.NewReader(cfgJSON)
	var stdout bytes.Buffer
	cmd := exec.Command(fmt.Sprintf("/proc/%d/exe", os.Getpid()))
	cmd.Args = []string{rootlessport.ReexecKey}
	// Leak one end of the pipe in rootlessport process, the other will be sent to conmon

	if ctr.rootlessPortSyncR != nil {
		defer errorhandling.CloseQuiet(ctr.rootlessPortSyncR)
	}

	cmd.ExtraFiles = append(cmd.ExtraFiles, ctr.rootlessPortSyncR, syncW)
	cmd.Stdin = cfgR
	// stdout is for human-readable error, stderr is for debug log
	cmd.Stdout = &stdout
	cmd.Stderr = io.MultiWriter(logFile, &logrusDebugWriter{"rootlessport: "})
	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setpgid: true,
	}
	if err := cmd.Start(); err != nil {
		return errors.Wrapf(err, "failed to start rootlessport process")
	}
	defer func() {
		if err := cmd.Process.Release(); err != nil {
			logrus.Errorf("unable to release rootlessport process: %q", err)
		}
	}()
	if err := waitForSync(syncR, cmd, logFile, 3*time.Second); err != nil {
		stdoutStr := stdout.String()
		if stdoutStr != "" {
			// err contains full debug log and too verbose, so return stdoutStr
			logrus.Debug(err)
			return errors.Errorf("failed to expose ports via rootlessport: %q", stdoutStr)
		}
		return err
	}
	logrus.Debug("rootlessport is ready")
	return nil
}

func (r *Runtime) setupRootlessPortMappingViaSlirp(ctr *Container, cmd *exec.Cmd, apiSocket string) (err error) {
	const pidWaitTimeout = 60 * time.Second
	chWait := make(chan error)
	go func() {
		interval := 25 * time.Millisecond
		for i := time.Duration(0); i < pidWaitTimeout; i += interval {
			// Check if the process is still running.
			var status syscall.WaitStatus
			pid, err := syscall.Wait4(cmd.Process.Pid, &status, syscall.WNOHANG, nil)
			if err != nil {
				break
			}
			if pid != cmd.Process.Pid {
				continue
			}
			if status.Exited() || status.Signaled() {
				chWait <- fmt.Errorf("slirp4netns exited with status %d", status.ExitStatus())
			}
			time.Sleep(interval)
		}
	}()
	defer close(chWait)

	// wait that API socket file appears before trying to use it.
	if _, err := WaitForFile(apiSocket, chWait, pidWaitTimeout); err != nil {
		return errors.Wrapf(err, "waiting for slirp4nets to create the api socket file %s", apiSocket)
	}

	// for each port we want to add we need to open a connection to the slirp4netns control socket
	// and send the add_hostfwd command.
	for _, i := range ctr.config.PortMappings {
		conn, err := net.Dial("unix", apiSocket)
		if err != nil {
			return errors.Wrapf(err, "cannot open connection to %s", apiSocket)
		}
		defer func() {
			if err := conn.Close(); err != nil {
				logrus.Errorf("unable to close connection: %q", err)
			}
		}()
		hostIP := i.HostIP
		if hostIP == "" {
			hostIP = "0.0.0.0"
		}
		apiCmd := slirp4netnsCmd{
			Execute: "add_hostfwd",
			Args: slirp4netnsCmdArg{
				Proto:     i.Protocol,
				HostAddr:  hostIP,
				HostPort:  i.HostPort,
				GuestPort: i.ContainerPort,
			},
		}
		// create the JSON payload and send it.  Mark the end of request shutting down writes
		// to the socket, as requested by slirp4netns.
		data, err := json.Marshal(&apiCmd)
		if err != nil {
			return errors.Wrapf(err, "cannot marshal JSON for slirp4netns")
		}
		if _, err := conn.Write([]byte(fmt.Sprintf("%s\n", data))); err != nil {
			return errors.Wrapf(err, "cannot write to control socket %s", apiSocket)
		}
		if err := conn.(*net.UnixConn).CloseWrite(); err != nil {
			return errors.Wrapf(err, "cannot shutdown the socket %s", apiSocket)
		}
		buf := make([]byte, 2048)
		readLength, err := conn.Read(buf)
		if err != nil {
			return errors.Wrapf(err, "cannot read from control socket %s", apiSocket)
		}
		// if there is no 'error' key in the received JSON data, then the operation was
		// successful.
		var y map[string]interface{}
		if err := json.Unmarshal(buf[0:readLength], &y); err != nil {
			return errors.Wrapf(err, "error parsing error status from slirp4netns")
		}
		if e, found := y["error"]; found {
			return errors.Errorf("error from slirp4netns while setting up port redirection: %v", e)
		}
	}
	logrus.Debug("slirp4netns port-forwarding setup via add_hostfwd is ready")
	return nil
}

// Configure the network namespace using the container process
func (r *Runtime) setupNetNS(ctr *Container) error {
	nsProcess := fmt.Sprintf("/proc/%d/ns/net", ctr.state.PID)

	b := make([]byte, 16)

	if _, err := rand.Reader.Read(b); err != nil {
		return errors.Wrapf(err, "failed to generate random netns name")
	}

	nsPath := fmt.Sprintf("/var/run/netns/cni-%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])

	if err := os.MkdirAll(filepath.Dir(nsPath), 0711); err != nil {
		return errors.Wrapf(err, "cannot create %s", filepath.Dir(nsPath))
	}

	mountPointFd, err := os.Create(nsPath)
	if err != nil {
		return errors.Wrapf(err, "cannot open %s", nsPath)
	}
	if err := mountPointFd.Close(); err != nil {
		return err
	}

	if err := unix.Mount(nsProcess, nsPath, "none", unix.MS_BIND, ""); err != nil {
		return errors.Wrapf(err, "cannot mount %s", nsPath)
	}

	netNS, err := ns.GetNS(nsPath)
	if err != nil {
		return err
	}
	networkStatus, err := r.configureNetNS(ctr, netNS)

	// Assign NetNS attributes to container
	ctr.state.NetNS = netNS
	ctr.state.NetworkStatus = networkStatus
	return err
}

// Join an existing network namespace
func joinNetNS(path string) (ns.NetNS, error) {
	netNS, err := ns.GetNS(path)
	if err != nil {
		return nil, errors.Wrapf(err, "error retrieving network namespace at %s", path)
	}

	return netNS, nil
}

// Close a network namespace.
// Differs from teardownNetNS() in that it will not attempt to undo the setup of
// the namespace, but will instead only close the open file descriptor
func (r *Runtime) closeNetNS(ctr *Container) error {
	if ctr.state.NetNS == nil {
		// The container has no network namespace, we're set
		return nil
	}

	if err := ctr.state.NetNS.Close(); err != nil {
		return errors.Wrapf(err, "error closing network namespace for container %s", ctr.ID())
	}

	ctr.state.NetNS = nil

	return nil
}

// Tear down a network namespace, undoing all state associated with it.
func (r *Runtime) teardownNetNS(ctr *Container) error {
	if ctr.state.NetNS == nil {
		// The container has no network namespace, we're set
		return nil
	}

	logrus.Debugf("Tearing down network namespace at %s for container %s", ctr.state.NetNS.Path(), ctr.ID())

	// rootless containers do not use the CNI plugin
	if !rootless.IsRootless() && !ctr.config.NetMode.IsSlirp4netns() {
		var requestedIP net.IP
		if ctr.requestedIP != nil {
			requestedIP = ctr.requestedIP
			// cancel request for a specific IP in case the container is reused later
			ctr.requestedIP = nil
		} else {
			requestedIP = ctr.config.StaticIP
		}

		var requestedMAC net.HardwareAddr
		if ctr.requestedMAC != nil {
			requestedMAC = ctr.requestedMAC
			// cancel request for a specific MAC in case the container is reused later
			ctr.requestedMAC = nil
		} else {
			requestedMAC = ctr.config.StaticMAC
		}

		podNetwork := r.getPodNetwork(ctr.ID(), ctr.Name(), ctr.state.NetNS.Path(), ctr.config.Networks, ctr.config.PortMappings, requestedIP, requestedMAC)

		if err := r.netPlugin.TearDownPod(podNetwork); err != nil {
			return errors.Wrapf(err, "error tearing down CNI namespace configuration for container %s", ctr.ID())
		}
	}

	// First unmount the namespace
	if err := netns.UnmountNS(ctr.state.NetNS); err != nil {
		return errors.Wrapf(err, "error unmounting network namespace for container %s", ctr.ID())
	}

	// Now close the open file descriptor
	if err := ctr.state.NetNS.Close(); err != nil {
		return errors.Wrapf(err, "error closing network namespace for container %s", ctr.ID())
	}

	ctr.state.NetNS = nil

	return nil
}

func getContainerNetNS(ctr *Container) (string, error) {
	if ctr.state.NetNS != nil {
		return ctr.state.NetNS.Path(), nil
	}
	if ctr.config.NetNsCtr != "" {
		c, err := ctr.runtime.GetContainer(ctr.config.NetNsCtr)
		if err != nil {
			return "", err
		}
		if err = c.syncContainer(); err != nil {
			return "", err
		}
		return getContainerNetNS(c)
	}
	return "", nil
}

func getContainerNetIO(ctr *Container) (*netlink.LinkStatistics, error) {
	var netStats *netlink.LinkStatistics
	// rootless v2 cannot seem to resolve its network connection to
	// collect statistics.  For now, we allow stats to at least run
	// by returning nil
	if rootless.IsRootless() {
		return netStats, nil
	}
	netNSPath, netPathErr := getContainerNetNS(ctr)
	if netPathErr != nil {
		return nil, netPathErr
	}
	if netNSPath == "" {
		// If netNSPath is empty, it was set as none, and no netNS was set up
		// this is a valid state and thus return no error, nor any statistics
		return nil, nil
	}
	err := ns.WithNetNSPath(netNSPath, func(_ ns.NetNS) error {
		link, err := netlink.LinkByName(ocicni.DefaultInterfaceName)
		if err != nil {
			return err
		}
		netStats = link.Attrs().Statistics
		return nil
	})
	return netStats, err
}

// Produce an InspectNetworkSettings containing information on the container
// network.
func (c *Container) getContainerNetworkInfo() (*define.InspectNetworkSettings, error) {
	settings := new(define.InspectNetworkSettings)
	settings.Ports = makeInspectPortBindings(c.config.PortMappings)

	// We can't do more if the network is down.
	if c.state.NetNS == nil {
		return settings, nil
	}

	// Set network namespace path
	settings.SandboxKey = c.state.NetNS.Path()

	// If this is empty, we're probably slirp4netns
	if len(c.state.NetworkStatus) == 0 {
		return settings, nil
	}

	// If we have CNI networks - handle that here
	if len(c.config.Networks) > 0 {
		if len(c.config.Networks) != len(c.state.NetworkStatus) {
			return nil, errors.Wrapf(define.ErrInternal, "network inspection mismatch: asked to join %d CNI networks but have information on %d networks", len(c.config.Networks), len(c.state.NetworkStatus))
		}

		settings.Networks = make(map[string]*define.InspectAdditionalNetwork)

		// CNI results should be in the same order as the list of
		// networks we pass into CNI.
		for index, name := range c.config.Networks {
			cniResult := c.state.NetworkStatus[index]
			addedNet := new(define.InspectAdditionalNetwork)
			addedNet.NetworkID = name

			basicConfig, err := resultToBasicNetworkConfig(cniResult)
			if err != nil {
				return nil, err
			}
			addedNet.InspectBasicNetworkConfig = basicConfig

			settings.Networks[name] = addedNet
		}

		return settings, nil
	}

	// If not joining networks, we should have at most 1 result
	if len(c.state.NetworkStatus) > 1 {
		return nil, errors.Wrapf(define.ErrInternal, "should have at most 1 CNI result if not joining networks, instead got %d", len(c.state.NetworkStatus))
	}

	if len(c.state.NetworkStatus) == 1 {
		basicConfig, err := resultToBasicNetworkConfig(c.state.NetworkStatus[0])
		if err != nil {
			return nil, err
		}

		settings.InspectBasicNetworkConfig = basicConfig
	}

	return settings, nil
}

// resultToBasicNetworkConfig produces an InspectBasicNetworkConfig from a CNI
// result
func resultToBasicNetworkConfig(result *cnitypes.Result) (define.InspectBasicNetworkConfig, error) {
	config := define.InspectBasicNetworkConfig{}

	for _, ctrIP := range result.IPs {
		size, _ := ctrIP.Address.Mask.Size()
		switch {
		case ctrIP.Version == "4" && config.IPAddress == "":
			config.IPAddress = ctrIP.Address.IP.String()
			config.IPPrefixLen = size
			config.Gateway = ctrIP.Gateway.String()
			if ctrIP.Interface != nil && *ctrIP.Interface < len(result.Interfaces) && *ctrIP.Interface > 0 {
				config.MacAddress = result.Interfaces[*ctrIP.Interface].Mac
			}
		case ctrIP.Version == "4" && config.IPAddress != "":
			config.SecondaryIPAddresses = append(config.SecondaryIPAddresses, ctrIP.Address.String())
			if ctrIP.Interface != nil && *ctrIP.Interface < len(result.Interfaces) && *ctrIP.Interface > 0 {
				config.AdditionalMacAddresses = append(config.AdditionalMacAddresses, result.Interfaces[*ctrIP.Interface].Mac)
			}
		case ctrIP.Version == "6" && config.IPAddress == "":
			config.GlobalIPv6Address = ctrIP.Address.IP.String()
			config.GlobalIPv6PrefixLen = size
			config.IPv6Gateway = ctrIP.Gateway.String()
		case ctrIP.Version == "6" && config.IPAddress != "":
			config.SecondaryIPv6Addresses = append(config.SecondaryIPv6Addresses, ctrIP.Address.String())
		default:
			return config, errors.Wrapf(define.ErrInternal, "unrecognized IP version %q", ctrIP.Version)
		}
	}

	return config, nil
}

// This is a horrible hack, necessary because CNI does not properly clean up
// after itself on an unclean reboot. Return what we're pretty sure is the path
// to CNI's internal files (it's not really exposed to us).
func getCNINetworksDir() (string, error) {
	return "/var/lib/cni/networks", nil
}

type logrusDebugWriter struct {
	prefix string
}

func (w *logrusDebugWriter) Write(p []byte) (int, error) {
	logrus.Debugf("%s%s", w.prefix, string(p))
	return len(p), nil
}