forked from aws/amazon-ecs-agent
-
Notifications
You must be signed in to change notification settings - Fork 0
/
init.go
444 lines (380 loc) · 13.1 KB
/
init.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
// +build linux
package namespaces
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"strings"
"syscall"
"github.com/docker/libcontainer"
"github.com/docker/libcontainer/apparmor"
"github.com/docker/libcontainer/console"
"github.com/docker/libcontainer/label"
"github.com/docker/libcontainer/mount"
"github.com/docker/libcontainer/netlink"
"github.com/docker/libcontainer/network"
"github.com/docker/libcontainer/security/capabilities"
"github.com/docker/libcontainer/security/restrict"
"github.com/docker/libcontainer/system"
"github.com/docker/libcontainer/user"
"github.com/docker/libcontainer/utils"
)
// TODO(vishh): This is part of the libcontainer API and it does much more than just namespaces related work.
// Move this to libcontainer package.
// Init is the init process that first runs inside a new namespace to setup mounts, users, networking,
// and other options required for the new container.
// The caller of Init function has to ensure that the go runtime is locked to an OS thread
// (using runtime.LockOSThread) else system calls like setns called within Init may not work as intended.
func Init(container *libcontainer.Config, uncleanRootfs, consolePath string, pipe *os.File, args []string) (err error) {
defer func() {
// if we have an error during the initialization of the container's init then send it back to the
// parent process in the form of an initError.
if err != nil {
// ensure that any data sent from the parent is consumed so it doesn't
// receive ECONNRESET when the child writes to the pipe.
ioutil.ReadAll(pipe)
if err := json.NewEncoder(pipe).Encode(initError{
Message: err.Error(),
}); err != nil {
panic(err)
}
}
// ensure that this pipe is always closed
pipe.Close()
}()
if container.Namespaces.Contains(libcontainer.NEWUSER) {
return initUserNs(container, uncleanRootfs, consolePath, pipe, args)
} else {
return initDefault(container, uncleanRootfs, consolePath, pipe, args)
}
}
func initDefault(container *libcontainer.Config, uncleanRootfs, consolePath string, pipe *os.File, args []string) (err error) {
rootfs, err := utils.ResolveRootfs(uncleanRootfs)
if err != nil {
return err
}
// clear the current processes env and replace it with the environment
// defined on the container
if err := LoadContainerEnvironment(container); err != nil {
return err
}
// We always read this as it is a way to sync with the parent as well
var networkState *network.NetworkState
if err := json.NewDecoder(pipe).Decode(&networkState); err != nil {
return err
}
// join any namespaces via a path to the namespace fd if provided
if err := joinExistingNamespaces(container.Namespaces); err != nil {
return err
}
if consolePath != "" {
if err := console.OpenAndDup(consolePath); err != nil {
return err
}
}
if _, err := syscall.Setsid(); err != nil {
return fmt.Errorf("setsid %s", err)
}
if consolePath != "" {
if err := system.Setctty(); err != nil {
return fmt.Errorf("setctty %s", err)
}
}
cloneFlags := GetNamespaceFlags(container.Namespaces)
if (cloneFlags & syscall.CLONE_NEWNET) == 0 {
if len(container.Networks) != 0 || len(container.Routes) != 0 {
return fmt.Errorf("unable to apply network parameters without network namespace")
}
} else {
if err := setupNetwork(container, networkState); err != nil {
return fmt.Errorf("setup networking %s", err)
}
if err := setupRoute(container); err != nil {
return fmt.Errorf("setup route %s", err)
}
}
if err := setupRlimits(container); err != nil {
return fmt.Errorf("setup rlimits %s", err)
}
label.Init()
// InitializeMountNamespace() can be executed only for a new mount namespace
if (cloneFlags & syscall.CLONE_NEWNS) == 0 {
if container.MountConfig != nil {
return fmt.Errorf("mount config is set without mount namespace")
}
} else if err := mount.InitializeMountNamespace(rootfs,
consolePath,
container.RestrictSys,
0, // Default Root Uid
0, // Default Root Gid
(*mount.MountConfig)(container.MountConfig)); err != nil {
return fmt.Errorf("setup mount namespace %s", err)
}
if container.Hostname != "" {
if (cloneFlags & syscall.CLONE_NEWUTS) == 0 {
return fmt.Errorf("unable to set the hostname without UTS namespace")
}
if err := syscall.Sethostname([]byte(container.Hostname)); err != nil {
return fmt.Errorf("unable to sethostname %q: %s", container.Hostname, err)
}
}
if err := apparmor.ApplyProfile(container.AppArmorProfile); err != nil {
return fmt.Errorf("set apparmor profile %s: %s", container.AppArmorProfile, err)
}
if err := label.SetProcessLabel(container.ProcessLabel); err != nil {
return fmt.Errorf("set process label %s", err)
}
// TODO: (crosbymichael) make this configurable at the Config level
if container.RestrictSys {
if (cloneFlags & syscall.CLONE_NEWNS) == 0 {
return fmt.Errorf("unable to restrict access to kernel files without mount namespace")
}
if err := restrict.Restrict("proc/sys", "proc/sysrq-trigger", "proc/irq", "proc/bus"); err != nil {
return err
}
}
pdeathSignal, err := system.GetParentDeathSignal()
if err != nil {
return fmt.Errorf("get parent death signal %s", err)
}
if err := FinalizeNamespace(container); err != nil {
return fmt.Errorf("finalize namespace %s", err)
}
// FinalizeNamespace can change user/group which clears the parent death
// signal, so we restore it here.
if err := RestoreParentDeathSignal(pdeathSignal); err != nil {
return fmt.Errorf("restore parent death signal %s", err)
}
return system.Execv(args[0], args[0:], os.Environ())
}
func initUserNs(container *libcontainer.Config, uncleanRootfs, consolePath string, pipe *os.File, args []string) (err error) {
// clear the current processes env and replace it with the environment
// defined on the container
if err := LoadContainerEnvironment(container); err != nil {
return err
}
// We always read this as it is a way to sync with the parent as well
var networkState *network.NetworkState
if err := json.NewDecoder(pipe).Decode(&networkState); err != nil {
return err
}
// join any namespaces via a path to the namespace fd if provided
if err := joinExistingNamespaces(container.Namespaces); err != nil {
return err
}
if consolePath != "" {
if err := console.OpenAndDup("/dev/console"); err != nil {
return err
}
}
if _, err := syscall.Setsid(); err != nil {
return fmt.Errorf("setsid %s", err)
}
if consolePath != "" {
if err := system.Setctty(); err != nil {
return fmt.Errorf("setctty %s", err)
}
}
if container.WorkingDir == "" {
container.WorkingDir = "/"
}
if err := setupRlimits(container); err != nil {
return fmt.Errorf("setup rlimits %s", err)
}
cloneFlags := GetNamespaceFlags(container.Namespaces)
if container.Hostname != "" {
if (cloneFlags & syscall.CLONE_NEWUTS) == 0 {
return fmt.Errorf("unable to set the hostname without UTS namespace")
}
if err := syscall.Sethostname([]byte(container.Hostname)); err != nil {
return fmt.Errorf("unable to sethostname %q: %s", container.Hostname, err)
}
}
if err := apparmor.ApplyProfile(container.AppArmorProfile); err != nil {
return fmt.Errorf("set apparmor profile %s: %s", container.AppArmorProfile, err)
}
if err := label.SetProcessLabel(container.ProcessLabel); err != nil {
return fmt.Errorf("set process label %s", err)
}
if container.RestrictSys {
if (cloneFlags & syscall.CLONE_NEWNS) == 0 {
return fmt.Errorf("unable to restrict access to kernel files without mount namespace")
}
if err := restrict.Restrict("proc/sys", "proc/sysrq-trigger", "proc/irq", "proc/bus"); err != nil {
return err
}
}
pdeathSignal, err := system.GetParentDeathSignal()
if err != nil {
return fmt.Errorf("get parent death signal %s", err)
}
if err := FinalizeNamespace(container); err != nil {
return fmt.Errorf("finalize namespace %s", err)
}
// FinalizeNamespace can change user/group which clears the parent death
// signal, so we restore it here.
if err := RestoreParentDeathSignal(pdeathSignal); err != nil {
return fmt.Errorf("restore parent death signal %s", err)
}
return system.Execv(args[0], args[0:], os.Environ())
}
// RestoreParentDeathSignal sets the parent death signal to old.
func RestoreParentDeathSignal(old int) error {
if old == 0 {
return nil
}
current, err := system.GetParentDeathSignal()
if err != nil {
return fmt.Errorf("get parent death signal %s", err)
}
if old == current {
return nil
}
if err := system.ParentDeathSignal(uintptr(old)); err != nil {
return fmt.Errorf("set parent death signal %s", err)
}
// Signal self if parent is already dead. Does nothing if running in a new
// PID namespace, as Getppid will always return 0.
if syscall.Getppid() == 1 {
return syscall.Kill(syscall.Getpid(), syscall.SIGKILL)
}
return nil
}
// SetupUser changes the groups, gid, and uid for the user inside the container
func SetupUser(container *libcontainer.Config) error {
// Set up defaults.
defaultExecUser := user.ExecUser{
Uid: syscall.Getuid(),
Gid: syscall.Getgid(),
Home: "/",
}
passwdPath, err := user.GetPasswdPath()
if err != nil {
return err
}
groupPath, err := user.GetGroupPath()
if err != nil {
return err
}
execUser, err := user.GetExecUserPath(container.User, &defaultExecUser, passwdPath, groupPath)
if err != nil {
return fmt.Errorf("get supplementary groups %s", err)
}
suppGroups := append(execUser.Sgids, container.AdditionalGroups...)
if err := syscall.Setgroups(suppGroups); err != nil {
return fmt.Errorf("setgroups %s", err)
}
if err := system.Setgid(execUser.Gid); err != nil {
return fmt.Errorf("setgid %s", err)
}
if err := system.Setuid(execUser.Uid); err != nil {
return fmt.Errorf("setuid %s", err)
}
// if we didn't get HOME already, set it based on the user's HOME
if envHome := os.Getenv("HOME"); envHome == "" {
if err := os.Setenv("HOME", execUser.Home); err != nil {
return fmt.Errorf("set HOME %s", err)
}
}
return nil
}
// setupVethNetwork uses the Network config if it is not nil to initialize
// the new veth interface inside the container for use by changing the name to eth0
// setting the MTU and IP address along with the default gateway
func setupNetwork(container *libcontainer.Config, networkState *network.NetworkState) error {
for _, config := range container.Networks {
strategy, err := network.GetStrategy(config.Type)
if err != nil {
return err
}
err1 := strategy.Initialize((*network.Network)(config), networkState)
if err1 != nil {
return err1
}
}
return nil
}
func setupRoute(container *libcontainer.Config) error {
for _, config := range container.Routes {
if err := netlink.AddRoute(config.Destination, config.Source, config.Gateway, config.InterfaceName); err != nil {
return err
}
}
return nil
}
func setupRlimits(container *libcontainer.Config) error {
for _, rlimit := range container.Rlimits {
l := &syscall.Rlimit{Max: rlimit.Hard, Cur: rlimit.Soft}
if err := syscall.Setrlimit(rlimit.Type, l); err != nil {
return fmt.Errorf("error setting rlimit type %v: %v", rlimit.Type, err)
}
}
return nil
}
// FinalizeNamespace drops the caps, sets the correct user
// and working dir, and closes any leaky file descriptors
// before execing the command inside the namespace
func FinalizeNamespace(container *libcontainer.Config) error {
// Ensure that all non-standard fds we may have accidentally
// inherited are marked close-on-exec so they stay out of the
// container
if err := utils.CloseExecFrom(3); err != nil {
return fmt.Errorf("close open file descriptors %s", err)
}
// drop capabilities in bounding set before changing user
if err := capabilities.DropBoundingSet(container.Capabilities); err != nil {
return fmt.Errorf("drop bounding set %s", err)
}
// preserve existing capabilities while we change users
if err := system.SetKeepCaps(); err != nil {
return fmt.Errorf("set keep caps %s", err)
}
if err := SetupUser(container); err != nil {
return fmt.Errorf("setup user %s", err)
}
if err := system.ClearKeepCaps(); err != nil {
return fmt.Errorf("clear keep caps %s", err)
}
// drop all other capabilities
if err := capabilities.DropCapabilities(container.Capabilities); err != nil {
return fmt.Errorf("drop capabilities %s", err)
}
if container.WorkingDir != "" {
if err := syscall.Chdir(container.WorkingDir); err != nil {
return fmt.Errorf("chdir to %s %s", container.WorkingDir, err)
}
}
return nil
}
func LoadContainerEnvironment(container *libcontainer.Config) error {
os.Clearenv()
for _, pair := range container.Env {
p := strings.SplitN(pair, "=", 2)
if len(p) < 2 {
return fmt.Errorf("invalid environment '%v'", pair)
}
if err := os.Setenv(p[0], p[1]); err != nil {
return err
}
}
return nil
}
// joinExistingNamespaces gets all the namespace paths specified for the container and
// does a setns on the namespace fd so that the current process joins the namespace.
func joinExistingNamespaces(namespaces []libcontainer.Namespace) error {
for _, ns := range namespaces {
if ns.Path != "" {
f, err := os.OpenFile(ns.Path, os.O_RDONLY, 0)
if err != nil {
return err
}
err = system.Setns(f.Fd(), uintptr(namespaceInfo[ns.Type]))
f.Close()
if err != nil {
return err
}
}
}
return nil
}