summaryrefslogtreecommitdiff
path: root/libpod/container_internal_linux.go
blob: 02f8d6aa48585e8c5e8826f216d60fab2e29c56f (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
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
// +build linux

package libpod

import (
	"context"
	"fmt"
	"io/ioutil"
	"net"
	"os"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"sync"
	"syscall"
	"time"

	cnitypes "github.com/containernetworking/cni/pkg/types/current"
	"github.com/containernetworking/plugins/pkg/ns"
	"github.com/containers/buildah/pkg/secrets"
	crioAnnotations "github.com/containers/libpod/pkg/annotations"
	"github.com/containers/libpod/pkg/apparmor"
	"github.com/containers/libpod/pkg/criu"
	"github.com/containers/libpod/pkg/lookup"
	"github.com/containers/libpod/pkg/resolvconf"
	"github.com/containers/libpod/pkg/rootless"
	"github.com/containers/storage/pkg/idtools"
	"github.com/cyphar/filepath-securejoin"
	"github.com/opencontainers/runc/libcontainer/user"
	spec "github.com/opencontainers/runtime-spec/specs-go"
	"github.com/opencontainers/runtime-tools/generate"
	"github.com/opencontainers/selinux/go-selinux/label"
	opentracing "github.com/opentracing/opentracing-go"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	"golang.org/x/sys/unix"
)

func (c *Container) mountSHM(shmOptions string) error {
	if err := unix.Mount("shm", c.config.ShmDir, "tmpfs", unix.MS_NOEXEC|unix.MS_NOSUID|unix.MS_NODEV,
		label.FormatMountLabel(shmOptions, c.config.MountLabel)); err != nil {
		return errors.Wrapf(err, "failed to mount shm tmpfs %q", c.config.ShmDir)
	}
	return nil
}

func (c *Container) unmountSHM(mount string) error {
	if err := unix.Unmount(mount, unix.MNT_DETACH); err != nil {
		if err != syscall.EINVAL {
			logrus.Warnf("container %s failed to unmount %s : %v", c.ID(), mount, err)
		}
	}
	return nil
}

// prepare mounts the container and sets up other required resources like net
// namespaces
func (c *Container) prepare() (err error) {
	var (
		wg                              sync.WaitGroup
		netNS                           ns.NetNS
		networkStatus                   []*cnitypes.Result
		createNetNSErr, mountStorageErr error
		mountPoint                      string
		tmpStateLock                    sync.Mutex
	)

	wg.Add(2)

	go func() {
		defer wg.Done()
		// Set up network namespace if not already set up
		if c.config.CreateNetNS && c.state.NetNS == nil && !c.config.PostConfigureNetNS {
			netNS, networkStatus, createNetNSErr = c.runtime.createNetNS(c)

			tmpStateLock.Lock()
			defer tmpStateLock.Unlock()

			// Assign NetNS attributes to container
			if createNetNSErr == nil {
				c.state.NetNS = netNS
				c.state.NetworkStatus = networkStatus
			}
		}
	}()
	// Mount storage if not mounted
	go func() {
		defer wg.Done()
		mountPoint, mountStorageErr = c.mountStorage()

		if mountStorageErr != nil {
			return
		}

		tmpStateLock.Lock()
		defer tmpStateLock.Unlock()

		// Finish up mountStorage
		c.state.Mounted = true
		c.state.Mountpoint = mountPoint
		if c.state.UserNSRoot == "" {
			c.state.RealMountpoint = c.state.Mountpoint
		} else {
			c.state.RealMountpoint = filepath.Join(c.state.UserNSRoot, "mountpoint")
		}

		logrus.Debugf("Created root filesystem for container %s at %s", c.ID(), c.state.Mountpoint)
	}()

	defer func() {
		if err != nil {
			if err2 := c.cleanupNetwork(); err2 != nil {
				logrus.Errorf("Error cleaning up container %s network: %v", c.ID(), err2)
			}
			if err2 := c.cleanupStorage(); err2 != nil {
				logrus.Errorf("Error cleaning up container %s storage: %v", c.ID(), err2)
			}
		}
	}()

	wg.Wait()

	if createNetNSErr != nil {
		if mountStorageErr != nil {
			logrus.Error(createNetNSErr)
			return mountStorageErr
		}
		return createNetNSErr
	}
	if mountStorageErr != nil {
		return mountStorageErr
	}

	// Save the container
	return c.save()
}

// cleanupNetwork unmounts and cleans up the container's network
func (c *Container) cleanupNetwork() error {
	if c.config.NetNsCtr != "" {
		return nil
	}
	netDisabled, err := c.NetworkDisabled()
	if err != nil {
		return err
	}
	if netDisabled {
		return nil
	}
	if c.state.NetNS == nil {
		logrus.Debugf("Network is already cleaned up, skipping...")
		return nil
	}

	// Stop the container's network namespace (if it has one)
	if err := c.runtime.teardownNetNS(c); err != nil {
		logrus.Errorf("unable to cleanup network for container %s: %q", c.ID(), err)
	}

	c.state.NetNS = nil
	c.state.NetworkStatus = nil

	if c.valid {
		return c.save()
	}

	return nil
}

// Generate spec for a container
// Accepts a map of the container's dependencies
func (c *Container) generateSpec(ctx context.Context) (*spec.Spec, error) {
	span, _ := opentracing.StartSpanFromContext(ctx, "generateSpec")
	span.SetTag("type", "container")
	defer span.Finish()

	execUser, err := lookup.GetUserGroupInfo(c.state.Mountpoint, c.config.User, nil)
	if err != nil {
		return nil, err
	}

	g := generate.NewFromSpec(c.config.Spec)

	// If network namespace was requested, add it now
	if c.config.CreateNetNS {
		if c.config.PostConfigureNetNS {
			g.AddOrReplaceLinuxNamespace(spec.NetworkNamespace, "")
		} else {
			g.AddOrReplaceLinuxNamespace(spec.NetworkNamespace, c.state.NetNS.Path())
		}
	}

	// Apply AppArmor checks and load the default profile if needed.
	updatedProfile, err := apparmor.CheckProfileAndLoadDefault(c.config.Spec.Process.ApparmorProfile)
	if err != nil {
		return nil, err
	}
	g.SetProcessApparmorProfile(updatedProfile)

	if err := c.makeBindMounts(); err != nil {
		return nil, err
	}
	// Check if the spec file mounts contain the label Relabel flags z or Z.
	// If they do, relabel the source directory and then remove the option.
	for i := range g.Config.Mounts {
		m := &g.Config.Mounts[i]
		var options []string
		for _, o := range m.Options {
			switch o {
			case "z":
				fallthrough
			case "Z":
				if err := label.Relabel(m.Source, c.MountLabel(), label.IsShared(o)); err != nil {
					return nil, errors.Wrapf(err, "relabel failed %q", m.Source)
				}

			default:
				options = append(options, o)
			}
		}
		m.Options = options

		// If we are using a user namespace, we will use an intermediate
		// directory to bind mount volumes
		if c.state.UserNSRoot != "" && strings.HasPrefix(m.Source, c.runtime.config.VolumePath) {
			newSourceDir := filepath.Join(c.state.UserNSRoot, "volumes")
			m.Source = strings.Replace(m.Source, c.runtime.config.VolumePath, newSourceDir, 1)
		}
	}

	g.SetProcessSelinuxLabel(c.ProcessLabel())
	g.SetLinuxMountLabel(c.MountLabel())
	// Add bind mounts to container
	for dstPath, srcPath := range c.state.BindMounts {
		newMount := spec.Mount{
			Type:        "bind",
			Source:      srcPath,
			Destination: dstPath,
			Options:     []string{"bind", "private"},
		}
		if c.IsReadOnly() && dstPath != "/dev/shm" {
			newMount.Options = append(newMount.Options, "ro", "nosuid", "noexec", "nodev")
		}
		if !MountExists(g.Mounts(), dstPath) {
			g.AddMount(newMount)
		} else {
			logrus.Warnf("User mount overriding libpod mount at %q", dstPath)
		}
	}

	if c.config.User != "" {
		// User and Group must go together
		g.SetProcessUID(uint32(execUser.Uid))
		g.SetProcessGID(uint32(execUser.Gid))
	}

	// Add addition groups if c.config.GroupAdd is not empty
	if len(c.config.Groups) > 0 {
		gids, _ := lookup.GetContainerGroups(c.config.Groups, c.state.Mountpoint, nil)
		for _, gid := range gids {
			g.AddProcessAdditionalGid(gid)
		}
	}

	if c.config.Systemd {
		if err := c.setupSystemd(g.Mounts(), g); err != nil {
			return nil, errors.Wrapf(err, "error adding systemd-specific mounts")
		}
	}

	// Look up and add groups the user belongs to, if a group wasn't directly specified
	if !rootless.IsRootless() && !strings.Contains(c.config.User, ":") {
		for _, gid := range execUser.Sgids {
			g.AddProcessAdditionalGid(uint32(gid))
		}
	}

	// Add shared namespaces from other containers
	if c.config.IPCNsCtr != "" {
		if err := c.addNamespaceContainer(&g, IPCNS, c.config.IPCNsCtr, spec.IPCNamespace); err != nil {
			return nil, err
		}
	}
	if c.config.MountNsCtr != "" {
		if err := c.addNamespaceContainer(&g, MountNS, c.config.MountNsCtr, spec.MountNamespace); err != nil {
			return nil, err
		}
	}
	if c.config.NetNsCtr != "" {
		if err := c.addNamespaceContainer(&g, NetNS, c.config.NetNsCtr, spec.NetworkNamespace); err != nil {
			return nil, err
		}
	}
	if c.config.PIDNsCtr != "" {
		if err := c.addNamespaceContainer(&g, PIDNS, c.config.PIDNsCtr, string(spec.PIDNamespace)); err != nil {
			return nil, err
		}
	}
	if c.config.UserNsCtr != "" {
		if err := c.addNamespaceContainer(&g, UserNS, c.config.UserNsCtr, spec.UserNamespace); err != nil {
			return nil, err
		}
	}
	if c.config.UTSNsCtr != "" {
		if err := c.addNamespaceContainer(&g, UTSNS, c.config.UTSNsCtr, spec.UTSNamespace); err != nil {
			return nil, err
		}
	}
	if c.config.CgroupNsCtr != "" {
		if err := c.addNamespaceContainer(&g, CgroupNS, c.config.CgroupNsCtr, spec.CgroupNamespace); err != nil {
			return nil, err
		}
	}

	if c.config.Rootfs == "" {
		if err := idtools.MkdirAllAs(c.state.RealMountpoint, 0700, c.RootUID(), c.RootGID()); err != nil {
			return nil, err
		}
	}

	g.SetRootPath(c.state.RealMountpoint)
	g.AddAnnotation(crioAnnotations.Created, c.config.CreatedTime.Format(time.RFC3339Nano))
	g.AddAnnotation("org.opencontainers.image.stopSignal", fmt.Sprintf("%d", c.config.StopSignal))

	for _, i := range c.config.Spec.Linux.Namespaces {
		if string(i.Type) == spec.UTSNamespace {
			hostname := c.Hostname()
			g.SetHostname(hostname)
			g.AddProcessEnv("HOSTNAME", hostname)
			break
		}
	}

	// Only add container environment variable if not already present
	foundContainerEnv := false
	for _, env := range g.Config.Process.Env {
		if strings.HasPrefix(env, "container=") {
			foundContainerEnv = true
			break
		}
	}
	if !foundContainerEnv {
		g.AddProcessEnv("container", "libpod")
	}

	if rootless.IsRootless() {
		g.SetLinuxCgroupsPath("")
	} else if c.runtime.config.CgroupManager == SystemdCgroupsManager {
		// When runc is set to use Systemd as a cgroup manager, it
		// expects cgroups to be passed as follows:
		// slice:prefix:name
		systemdCgroups := fmt.Sprintf("%s:libpod:%s", path.Base(c.config.CgroupParent), c.ID())
		logrus.Debugf("Setting CGroups for container %s to %s", c.ID(), systemdCgroups)
		g.SetLinuxCgroupsPath(systemdCgroups)
	} else {
		cgroupPath, err := c.CGroupPath()
		if err != nil {
			return nil, err
		}
		logrus.Debugf("Setting CGroup path for container %s to %s", c.ID(), cgroupPath)
		g.SetLinuxCgroupsPath(cgroupPath)
	}

	// Mounts need to be sorted so paths will not cover other paths
	mounts := sortMounts(g.Mounts())
	g.ClearMounts()

	// Determine property of RootPropagation based on volume properties. If
	// a volume is shared, then keep root propagation shared. This should
	// work for slave and private volumes too.
	//
	// For slave volumes, it can be either [r]shared/[r]slave.
	//
	// For private volumes any root propagation value should work.
	rootPropagation := ""
	for _, m := range mounts {
		// We need to remove all symlinks from tmpfs mounts.
		// Runc and other runtimes may choke on them.
		// Easy solution: use securejoin to do a scoped evaluation of
		// the links, then trim off the mount prefix.
		if m.Type == "tmpfs" {
			finalPath, err := securejoin.SecureJoin(c.state.Mountpoint, m.Destination)
			if err != nil {
				return nil, errors.Wrapf(err, "error resolving symlinks for mount destination %s", m.Destination)
			}
			trimmedPath := strings.TrimPrefix(finalPath, strings.TrimSuffix(c.state.Mountpoint, "/"))
			m.Destination = trimmedPath
		}
		g.AddMount(m)
		for _, opt := range m.Options {
			switch opt {
			case MountShared, MountRShared:
				if rootPropagation != MountShared && rootPropagation != MountRShared {
					rootPropagation = MountShared
				}
			case MountSlave, MountRSlave:
				if rootPropagation != MountShared && rootPropagation != MountRShared && rootPropagation != MountSlave && rootPropagation != MountRSlave {
					rootPropagation = MountRSlave
				}
			}
		}
	}

	if rootPropagation != "" {
		logrus.Debugf("set root propagation to %q", rootPropagation)
		g.SetLinuxRootPropagation(rootPropagation)
	}

	// Warning: precreate hooks may alter g.Config in place.
	if c.state.ExtensionStageHooks, err = c.setupOCIHooks(ctx, g.Config); err != nil {
		return nil, errors.Wrapf(err, "error setting up OCI Hooks")
	}

	return g.Config, nil
}

// systemd expects to have /run, /run/lock and /tmp on tmpfs
// It also expects to be able to write to /sys/fs/cgroup/systemd and /var/log/journal
func (c *Container) setupSystemd(mounts []spec.Mount, g generate.Generator) error {
	options := []string{"rw", "rprivate", "noexec", "nosuid", "nodev"}
	for _, dest := range []string{"/run", "/run/lock"} {
		if MountExists(mounts, dest) {
			continue
		}
		tmpfsMnt := spec.Mount{
			Destination: dest,
			Type:        "tmpfs",
			Source:      "tmpfs",
			Options:     append(options, "tmpcopyup", "size=65536k"),
		}
		g.AddMount(tmpfsMnt)
	}
	for _, dest := range []string{"/tmp", "/var/log/journal"} {
		if MountExists(mounts, dest) {
			continue
		}
		tmpfsMnt := spec.Mount{
			Destination: dest,
			Type:        "tmpfs",
			Source:      "tmpfs",
			Options:     append(options, "tmpcopyup"),
		}
		g.AddMount(tmpfsMnt)
	}

	// rootless containers have no write access to /sys/fs/cgroup, so don't
	// add any mount into the container.
	if !rootless.IsRootless() {
		cgroupPath, err := c.CGroupPath()
		if err != nil {
			return err
		}
		sourcePath := filepath.Join("/sys/fs/cgroup/systemd", cgroupPath)

		systemdMnt := spec.Mount{
			Destination: "/sys/fs/cgroup/systemd",
			Type:        "bind",
			Source:      sourcePath,
			Options:     []string{"bind", "private"},
		}
		g.AddMount(systemdMnt)
	} else {
		systemdMnt := spec.Mount{
			Destination: "/sys/fs/cgroup/systemd",
			Type:        "bind",
			Source:      "/sys/fs/cgroup/systemd",
			Options:     []string{"bind", "nodev", "noexec", "nosuid"},
		}
		g.AddMount(systemdMnt)
	}

	return nil
}

// Add an existing container's namespace to the spec
func (c *Container) addNamespaceContainer(g *generate.Generator, ns LinuxNS, ctr string, specNS string) error {
	nsCtr, err := c.runtime.state.Container(ctr)
	if err != nil {
		return errors.Wrapf(err, "error retrieving dependency %s of container %s from state", ctr, c.ID())
	}

	// TODO need unlocked version of this for use in pods
	nsPath, err := nsCtr.NamespacePath(ns)
	if err != nil {
		return err
	}

	if err := g.AddOrReplaceLinuxNamespace(specNS, nsPath); err != nil {
		return err
	}

	return nil
}

func (c *Container) checkpointRestoreSupported() (err error) {
	if !criu.CheckForCriu() {
		return errors.Errorf("Checkpoint/Restore requires at least CRIU %d", criu.MinCriuVersion)
	}
	if !c.runtime.ociRuntime.featureCheckCheckpointing() {
		return errors.Errorf("Configured runtime does not support checkpoint/restore")
	}
	return nil
}

func (c *Container) checkpoint(ctx context.Context, options ContainerCheckpointOptions) (err error) {
	if err := c.checkpointRestoreSupported(); err != nil {
		return err
	}

	if c.state.State != ContainerStateRunning {
		return errors.Wrapf(ErrCtrStateInvalid, "%q is not running, cannot checkpoint", c.state.State)
	}

	// Create the CRIU log file and label it
	dumpLog := filepath.Join(c.bundlePath(), "dump.log")

	logFile, err := os.OpenFile(dumpLog, os.O_CREATE, 0600)
	if err != nil {
		return errors.Wrapf(err, "failed to create CRIU log file %q", dumpLog)
	}
	logFile.Close()
	if err = label.SetFileLabel(dumpLog, c.MountLabel()); err != nil {
		return errors.Wrapf(err, "failed to label CRIU log file %q", dumpLog)
	}

	if err := c.runtime.ociRuntime.checkpointContainer(c, options); err != nil {
		return err
	}

	// Save network.status. This is needed to restore the container with
	// the same IP. Currently limited to one IP address in a container
	// with one interface.
	formatJSON, err := json.MarshalIndent(c.state.NetworkStatus, "", "     ")
	if err != nil {
		return err
	}
	if err := ioutil.WriteFile(filepath.Join(c.bundlePath(), "network.status"), formatJSON, 0644); err != nil {
		return err
	}

	logrus.Debugf("Checkpointed container %s", c.ID())

	if !options.KeepRunning {
		c.state.State = ContainerStateStopped

		// Cleanup Storage and Network
		if err := c.cleanup(ctx); err != nil {
			return err
		}
	}

	if !options.Keep {
		// Remove log file
		os.Remove(filepath.Join(c.bundlePath(), "dump.log"))
		// Remove statistic file
		os.Remove(filepath.Join(c.bundlePath(), "stats-dump"))
	}

	return c.save()
}

func (c *Container) restore(ctx context.Context, options ContainerCheckpointOptions) (err error) {

	if err := c.checkpointRestoreSupported(); err != nil {
		return err
	}

	if (c.state.State != ContainerStateConfigured) && (c.state.State != ContainerStateExited) {
		return errors.Wrapf(ErrCtrStateInvalid, "container %s is running or paused, cannot restore", c.ID())
	}

	// Let's try to stat() CRIU's inventory file. If it does not exist, it makes
	// no sense to try a restore. This is a minimal check if a checkpoint exist.
	if _, err := os.Stat(filepath.Join(c.CheckpointPath(), "inventory.img")); os.IsNotExist(err) {
		return errors.Wrapf(err, "A complete checkpoint for this container cannot be found, cannot restore")
	}

	// Read network configuration from checkpoint
	// Currently only one interface with one IP is supported.
	networkStatusFile, err := os.Open(filepath.Join(c.bundlePath(), "network.status"))
	if err == nil {
		// The file with the network.status does exist. Let's restore the
		// container with the same IP address as during checkpointing.
		defer networkStatusFile.Close()
		var networkStatus []*cnitypes.Result
		networkJSON, err := ioutil.ReadAll(networkStatusFile)
		if err != nil {
			return err
		}
		json.Unmarshal(networkJSON, &networkStatus)
		// Take the first IP address
		var IP net.IP
		if len(networkStatus) > 0 {
			if len(networkStatus[0].IPs) > 0 {
				IP = networkStatus[0].IPs[0].Address.IP
			}
		}
		if IP != nil {
			// Tell CNI which IP address we want.
			c.requestedIP = IP
		}
	}

	defer func() {
		if err != nil {
			if err2 := c.cleanup(ctx); err2 != nil {
				logrus.Errorf("error cleaning up container %s: %v", c.ID(), err2)
			}
		}
	}()

	if err := c.prepare(); err != nil {
		return err
	}

	// Read config
	jsonPath := filepath.Join(c.bundlePath(), "config.json")
	logrus.Debugf("generate.NewFromFile at %v", jsonPath)
	g, err := generate.NewFromFile(jsonPath)
	if err != nil {
		logrus.Debugf("generate.NewFromFile failed with %v", err)
		return err
	}

	// We want to have the same network namespace as before.
	if c.config.CreateNetNS {
		g.AddOrReplaceLinuxNamespace(spec.NetworkNamespace, c.state.NetNS.Path())
	}

	// Save the OCI spec to disk
	if err := c.saveSpec(g.Spec()); err != nil {
		return err
	}

	if err := c.makeBindMounts(); err != nil {
		return err
	}

	// Cleanup for a working restore.
	c.removeConmonFiles()

	if err := c.runtime.ociRuntime.createContainer(c, c.config.CgroupParent, &options); err != nil {
		return err
	}

	logrus.Debugf("Restored container %s", c.ID())

	c.state.State = ContainerStateRunning

	if !options.Keep {
		// Delete all checkpoint related files. At this point, in theory, all files
		// should exist. Still ignoring errors for now as the container should be
		// restored and running. Not erroring out just because some cleanup operation
		// failed. Starting with the checkpoint directory
		err = os.RemoveAll(c.CheckpointPath())
		if err != nil {
			logrus.Debugf("Non-fatal: removal of checkpoint directory (%s) failed: %v", c.CheckpointPath(), err)
		}
		cleanup := [...]string{"restore.log", "dump.log", "stats-dump", "stats-restore", "network.status"}
		for _, delete := range cleanup {
			file := filepath.Join(c.bundlePath(), delete)
			err = os.Remove(file)
			if err != nil {
				logrus.Debugf("Non-fatal: removal of checkpoint file (%s) failed: %v", file, err)
			}
		}
	}

	return c.save()
}

// Make standard bind mounts to include in the container
func (c *Container) makeBindMounts() error {
	if err := os.Chown(c.state.RunDir, c.RootUID(), c.RootGID()); err != nil {
		return errors.Wrapf(err, "cannot chown run directory %s", c.state.RunDir)
	}

	if c.state.BindMounts == nil {
		c.state.BindMounts = make(map[string]string)
	}
	netDisabled, err := c.NetworkDisabled()
	if err != nil {
		return err
	}

	if !netDisabled {
		// If /etc/resolv.conf and /etc/hosts exist, delete them so we
		// will recreate. Only do this if we aren't sharing them with
		// another container.
		if c.config.NetNsCtr == "" {
			if path, ok := c.state.BindMounts["/etc/resolv.conf"]; ok {
				if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
					return errors.Wrapf(err, "error removing container %s resolv.conf", c.ID())
				}
				delete(c.state.BindMounts, "/etc/resolv.conf")
			}
			if path, ok := c.state.BindMounts["/etc/hosts"]; ok {
				if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
					return errors.Wrapf(err, "error removing container %s hosts", c.ID())
				}
				delete(c.state.BindMounts, "/etc/hosts")
			}
		}

		if c.config.NetNsCtr != "" && (!c.config.UseImageResolvConf || !c.config.UseImageHosts) {
			// We share a net namespace.
			// We want /etc/resolv.conf and /etc/hosts from the
			// other container. Unless we're not creating both of
			// them.
			depCtr, err := c.runtime.state.Container(c.config.NetNsCtr)
			if err != nil {
				return errors.Wrapf(err, "error fetching dependency %s of container %s", c.config.NetNsCtr, c.ID())
			}

			// We need that container's bind mounts
			bindMounts, err := depCtr.BindMounts()
			if err != nil {
				return errors.Wrapf(err, "error fetching bind mounts from dependency %s of container %s", depCtr.ID(), c.ID())
			}

			if !c.config.UseImageResolvConf {
				// The other container may not have a resolv.conf or /etc/hosts
				// If it doesn't, don't copy them
				resolvPath, exists := bindMounts["/etc/resolv.conf"]
				if exists {
					c.state.BindMounts["/etc/resolv.conf"] = resolvPath
				}
			}

			if !c.config.UseImageHosts {
				// check if dependency container has an /etc/hosts file
				hostsPath, exists := bindMounts["/etc/hosts"]
				if !exists {
					return errors.Errorf("error finding hosts file of dependency container %s for container %s", depCtr.ID(), c.ID())
				}

				depCtr.lock.Lock()
				// generate a hosts file for the dependency container,
				// based on either its old hosts file, or the default,
				// and add the relevant information from the new container (hosts and IP)
				hostsPath, err = depCtr.appendHosts(hostsPath, c)

				if err != nil {
					depCtr.lock.Unlock()
					return errors.Wrapf(err, "error creating hosts file for container %s which depends on container %s", c.ID(), depCtr.ID())
				}
				depCtr.lock.Unlock()

				// finally, save it in the new container
				c.state.BindMounts["/etc/hosts"] = hostsPath
			}
		} else {
			if !c.config.UseImageResolvConf {
				newResolv, err := c.generateResolvConf()
				if err != nil {
					return errors.Wrapf(err, "error creating resolv.conf for container %s", c.ID())
				}
				c.state.BindMounts["/etc/resolv.conf"] = newResolv
			}

			if !c.config.UseImageHosts {
				newHosts, err := c.generateHosts("/etc/hosts")
				if err != nil {
					return errors.Wrapf(err, "error creating hosts file for container %s", c.ID())
				}
				c.state.BindMounts["/etc/hosts"] = newHosts
			}
		}

		if c.state.BindMounts["/etc/hosts"] != "" {
			if err := label.Relabel(c.state.BindMounts["/etc/hosts"], c.config.MountLabel, true); err != nil {
				return err
			}
		}

		if c.state.BindMounts["/etc/resolv.conf"] != "" {
			if err := label.Relabel(c.state.BindMounts["/etc/resolv.conf"], c.config.MountLabel, true); err != nil {
				return err
			}
		}
	}

	// SHM is always added when we mount the container
	c.state.BindMounts["/dev/shm"] = c.config.ShmDir

	newPasswd, err := c.generatePasswd()
	if err != nil {
		return errors.Wrapf(err, "error creating temporary passwd file for container %s", c.ID())
	}
	if newPasswd != "" {
		// Make /etc/passwd
		if _, ok := c.state.BindMounts["/etc/passwd"]; ok {
			// If it already exists, delete so we can recreate
			delete(c.state.BindMounts, "/etc/passwd")
		}
		logrus.Debugf("adding entry to /etc/passwd for non existent default user")
		c.state.BindMounts["/etc/passwd"] = newPasswd
	}

	// Make /etc/hostname
	// This should never change, so no need to recreate if it exists
	if _, ok := c.state.BindMounts["/etc/hostname"]; !ok {
		hostnamePath, err := c.writeStringToRundir("hostname", c.Hostname())
		if err != nil {
			return errors.Wrapf(err, "error creating hostname file for container %s", c.ID())
		}
		c.state.BindMounts["/etc/hostname"] = hostnamePath
	}

	// Make .containerenv
	// Empty file, so no need to recreate if it exists
	if _, ok := c.state.BindMounts["/run/.containerenv"]; !ok {
		// Empty string for now, but we may consider populating this later
		containerenvPath, err := c.writeStringToRundir(".containerenv", "")
		if err != nil {
			return errors.Wrapf(err, "error creating containerenv file for container %s", c.ID())
		}
		c.state.BindMounts["/run/.containerenv"] = containerenvPath
	}

	// Add Secret Mounts
	secretMounts := secrets.SecretMountsWithUIDGID(c.config.MountLabel, c.state.RunDir, c.runtime.config.DefaultMountsFile, c.state.DestinationRunDir, c.RootUID(), c.RootGID())
	for _, mount := range secretMounts {
		if _, ok := c.state.BindMounts[mount.Destination]; !ok {
			c.state.BindMounts[mount.Destination] = mount.Source
		}
	}

	return nil
}

// generateResolvConf generates a containers resolv.conf
func (c *Container) generateResolvConf() (string, error) {
	resolvConf := "/etc/resolv.conf"
	for _, ns := range c.config.Spec.Linux.Namespaces {
		if ns.Type == spec.NetworkNamespace {
			if ns.Path != "" && !strings.HasPrefix(ns.Path, "/proc/") {
				definedPath := filepath.Join("/etc/netns", filepath.Base(ns.Path), "resolv.conf")
				_, err := os.Stat(definedPath)
				if err == nil {
					resolvConf = definedPath
				} else if !os.IsNotExist(err) {
					return "", errors.Wrapf(err, "failed to stat %s", definedPath)
				}
			}
			break
		}
	}

	// Determine the endpoint for resolv.conf in case it is a symlink
	resolvPath, err := filepath.EvalSymlinks(resolvConf)
	if err != nil {
		return "", err
	}

	contents, err := ioutil.ReadFile(resolvPath)
	if err != nil {
		return "", errors.Wrapf(err, "unable to read %s", resolvPath)
	}

	// Ensure that the container's /etc/resolv.conf is compatible with its
	// network configuration.
	// TODO: set ipv6 enable bool more sanely
	resolv, err := resolvconf.FilterResolvDNS(contents, true, c.config.CreateNetNS)
	if err != nil {
		return "", errors.Wrapf(err, "error parsing host resolv.conf")
	}

	// Make a new resolv.conf
	nameservers := resolvconf.GetNameservers(resolv.Content)
	// slirp4netns has a built in DNS server.
	if c.config.NetMode.IsSlirp4netns() {
		nameservers = append(nameservers, "10.0.2.3")
	}
	if len(c.config.DNSServer) > 0 {
		// We store DNS servers as net.IP, so need to convert to string
		nameservers = []string{}
		for _, server := range c.config.DNSServer {
			nameservers = append(nameservers, server.String())
		}
	}

	search := resolvconf.GetSearchDomains(resolv.Content)
	if len(c.config.DNSSearch) > 0 {
		search = c.config.DNSSearch
	}

	options := resolvconf.GetOptions(resolv.Content)
	if len(c.config.DNSOption) > 0 {
		options = c.config.DNSOption
	}

	destPath := filepath.Join(c.state.RunDir, "resolv.conf")

	if err := os.Remove(destPath); err != nil && !os.IsNotExist(err) {
		return "", errors.Wrapf(err, "error removing resolv.conf for container %s", c.ID())
	}

	// Build resolv.conf
	if _, err = resolvconf.Build(destPath, nameservers, search, options); err != nil {
		return "", errors.Wrapf(err, "error building resolv.conf for container %s", c.ID())
	}

	// Relabel resolv.conf for the container
	if err := label.Relabel(destPath, c.config.MountLabel, true); err != nil {
		return "", err
	}

	return filepath.Join(c.state.DestinationRunDir, "resolv.conf"), nil
}

// generateHosts creates a containers hosts file
func (c *Container) generateHosts(path string) (string, error) {
	orig, err := ioutil.ReadFile(path)
	if err != nil {
		return "", errors.Wrapf(err, "unable to read %s", path)
	}
	hosts := string(orig)
	hosts += c.getHosts()
	return c.writeStringToRundir("hosts", hosts)
}

// appendHosts appends a container's config and state pertaining to hosts to a container's
// local hosts file. netCtr is the container from which the netNS information is
// taken.
// path is the basis of the hosts file, into which netCtr's netNS information will be appended.
func (c *Container) appendHosts(path string, netCtr *Container) (string, error) {
	return c.appendStringToRundir("hosts", netCtr.getHosts())
}

// getHosts finds the pertinent information for a container's host file in its config and state
// and returns a string in a format that can be written to the host file
func (c *Container) getHosts() string {
	var hosts string
	if len(c.config.HostAdd) > 0 {
		for _, host := range c.config.HostAdd {
			// the host format has already been verified at this point
			fields := strings.SplitN(host, ":", 2)
			hosts += fmt.Sprintf("%s %s\n", fields[1], fields[0])
		}
	}
	if len(c.state.NetworkStatus) > 0 && len(c.state.NetworkStatus[0].IPs) > 0 {
		ipAddress := strings.Split(c.state.NetworkStatus[0].IPs[0].Address.String(), "/")[0]
		hosts += fmt.Sprintf("%s\t%s\n", ipAddress, c.Hostname())
	}
	return hosts
}

// generatePasswd generates a container specific passwd file,
// iff g.config.User is a number
func (c *Container) generatePasswd() (string, error) {
	var (
		groupspec string
		gid       int
	)
	if c.config.User == "" {
		return "", nil
	}
	spec := strings.SplitN(c.config.User, ":", 2)
	userspec := spec[0]
	if len(spec) > 1 {
		groupspec = spec[1]
	}
	// If a non numeric User, then don't generate passwd
	uid, err := strconv.ParseUint(userspec, 10, 32)
	if err != nil {
		return "", nil
	}
	// Lookup the user to see if it exists in the container image
	_, err = lookup.GetUser(c.state.Mountpoint, userspec)
	if err != nil && err != user.ErrNoPasswdEntries {
		return "", err
	}
	if err == nil {
		return "", nil
	}
	if groupspec != "" {
		ugid, err := strconv.ParseUint(groupspec, 10, 32)
		if err == nil {
			gid = int(ugid)
		} else {
			group, err := lookup.GetGroup(c.state.Mountpoint, groupspec)
			if err != nil {
				return "", errors.Wrapf(err, "unable to get gid %s from group file", groupspec)
			}
			gid = group.Gid
		}
	}
	originPasswdFile := filepath.Join(c.state.Mountpoint, "/etc/passwd")
	orig, err := ioutil.ReadFile(originPasswdFile)
	if err != nil && !os.IsNotExist(err) {
		return "", errors.Wrapf(err, "unable to read passwd file %s", originPasswdFile)
	}

	pwd := fmt.Sprintf("%s%d:x:%d:%d:container user:%s:/bin/sh\n", orig, uid, uid, gid, c.WorkingDir())
	passwdFile, err := c.writeStringToRundir("passwd", pwd)
	if err != nil {
		return "", errors.Wrapf(err, "failed to create temporary passwd file")
	}
	if os.Chmod(passwdFile, 0644); err != nil {
		return "", err
	}
	return passwdFile, nil
}

func (c *Container) copyOwnerAndPerms(source, dest string) error {
	info, err := os.Stat(source)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return errors.Wrapf(err, "cannot stat `%s`", dest)
	}
	if err := os.Chmod(dest, info.Mode()); err != nil {
		return errors.Wrapf(err, "cannot chmod `%s`", dest)
	}
	if err := os.Chown(dest, int(info.Sys().(*syscall.Stat_t).Uid), int(info.Sys().(*syscall.Stat_t).Gid)); err != nil {
		return errors.Wrapf(err, "cannot chown `%s`", dest)
	}
	return nil
}