forked from kubernetes/kubernetes
-
Notifications
You must be signed in to change notification settings - Fork 0
/
process_linux.go
405 lines (367 loc) · 9.53 KB
/
process_linux.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
// +build linux
package libcontainer
import (
"encoding/json"
"errors"
"fmt"
"io"
"os"
"os/exec"
"path/filepath"
"strconv"
"syscall"
"github.com/opencontainers/runc/libcontainer/cgroups"
"github.com/opencontainers/runc/libcontainer/configs"
"github.com/opencontainers/runc/libcontainer/system"
"github.com/opencontainers/runc/libcontainer/utils"
)
type parentProcess interface {
// pid returns the pid for the running process.
pid() int
// start starts the process execution.
start() error
// send a SIGKILL to the process and wait for the exit.
terminate() error
// wait waits on the process returning the process state.
wait() (*os.ProcessState, error)
// startTime return's the process start time.
startTime() (string, error)
signal(os.Signal) error
externalDescriptors() []string
setExternalDescriptors(fds []string)
}
type setnsProcess struct {
cmd *exec.Cmd
parentPipe *os.File
childPipe *os.File
cgroupPaths map[string]string
config *initConfig
fds []string
process *Process
bootstrapData io.Reader
}
func (p *setnsProcess) startTime() (string, error) {
return system.GetProcessStartTime(p.pid())
}
func (p *setnsProcess) signal(sig os.Signal) error {
s, ok := sig.(syscall.Signal)
if !ok {
return errors.New("os: unsupported signal type")
}
return syscall.Kill(p.pid(), s)
}
func (p *setnsProcess) start() (err error) {
defer p.parentPipe.Close()
err = p.cmd.Start()
p.childPipe.Close()
if err != nil {
return newSystemError(err)
}
if p.bootstrapData != nil {
if _, err := io.Copy(p.parentPipe, p.bootstrapData); err != nil {
return newSystemError(err)
}
}
if err = p.execSetns(); err != nil {
return newSystemError(err)
}
if len(p.cgroupPaths) > 0 {
if err := cgroups.EnterPid(p.cgroupPaths, p.pid()); err != nil {
return newSystemError(err)
}
}
if err := utils.WriteJSON(p.parentPipe, p.config); err != nil {
return newSystemError(err)
}
if err := syscall.Shutdown(int(p.parentPipe.Fd()), syscall.SHUT_WR); err != nil {
return newSystemError(err)
}
// wait for the child process to fully complete and receive an error message
// if one was encoutered
var ierr *genericError
if err := json.NewDecoder(p.parentPipe).Decode(&ierr); err != nil && err != io.EOF {
return newSystemError(err)
}
// Must be done after Shutdown so the child will exit and we can wait for it.
if ierr != nil {
p.wait()
return newSystemError(ierr)
}
return nil
}
// execSetns runs the process that executes C code to perform the setns calls
// because setns support requires the C process to fork off a child and perform the setns
// before the go runtime boots, we wait on the process to die and receive the child's pid
// over the provided pipe.
func (p *setnsProcess) execSetns() error {
status, err := p.cmd.Process.Wait()
if err != nil {
p.cmd.Wait()
return newSystemError(err)
}
if !status.Success() {
p.cmd.Wait()
return newSystemError(&exec.ExitError{ProcessState: status})
}
var pid *pid
if err := json.NewDecoder(p.parentPipe).Decode(&pid); err != nil {
p.cmd.Wait()
return newSystemError(err)
}
process, err := os.FindProcess(pid.Pid)
if err != nil {
return err
}
p.cmd.Process = process
p.process.ops = p
return nil
}
// terminate sends a SIGKILL to the forked process for the setns routine then waits to
// avoid the process becomming a zombie.
func (p *setnsProcess) terminate() error {
if p.cmd.Process == nil {
return nil
}
err := p.cmd.Process.Kill()
if _, werr := p.wait(); err == nil {
err = werr
}
return err
}
func (p *setnsProcess) wait() (*os.ProcessState, error) {
err := p.cmd.Wait()
// Return actual ProcessState even on Wait error
return p.cmd.ProcessState, err
}
func (p *setnsProcess) pid() int {
return p.cmd.Process.Pid
}
func (p *setnsProcess) externalDescriptors() []string {
return p.fds
}
func (p *setnsProcess) setExternalDescriptors(newFds []string) {
p.fds = newFds
}
type initProcess struct {
cmd *exec.Cmd
parentPipe *os.File
childPipe *os.File
config *initConfig
manager cgroups.Manager
container *linuxContainer
fds []string
process *Process
}
func (p *initProcess) pid() int {
return p.cmd.Process.Pid
}
func (p *initProcess) externalDescriptors() []string {
return p.fds
}
func (p *initProcess) start() (err error) {
defer p.parentPipe.Close()
err = p.cmd.Start()
p.process.ops = p
p.childPipe.Close()
if err != nil {
p.process.ops = nil
return newSystemError(err)
}
// Save the standard descriptor names before the container process
// can potentially move them (e.g., via dup2()). If we don't do this now,
// we won't know at checkpoint time which file descriptor to look up.
fds, err := getPipeFds(p.pid())
if err != nil {
return newSystemError(err)
}
p.setExternalDescriptors(fds)
// Do this before syncing with child so that no children
// can escape the cgroup
if err := p.manager.Apply(p.pid()); err != nil {
return newSystemError(err)
}
defer func() {
if err != nil {
// TODO: should not be the responsibility to call here
p.manager.Destroy()
}
}()
if p.config.Config.Hooks != nil {
s := configs.HookState{
Version: p.container.config.Version,
ID: p.container.id,
Pid: p.pid(),
Root: p.config.Config.Rootfs,
}
for _, hook := range p.config.Config.Hooks.Prestart {
if err := hook.Run(s); err != nil {
return newSystemError(err)
}
}
}
if err := p.createNetworkInterfaces(); err != nil {
return newSystemError(err)
}
if err := p.sendConfig(); err != nil {
return newSystemError(err)
}
var (
procSync syncT
sentRun bool
ierr *genericError
)
loop:
for {
if err := json.NewDecoder(p.parentPipe).Decode(&procSync); err != nil {
if err == io.EOF {
break loop
}
return newSystemError(err)
}
switch procSync.Type {
case procStart:
break loop
case procReady:
if err := p.manager.Set(p.config.Config); err != nil {
return newSystemError(err)
}
// Sync with child.
if err := utils.WriteJSON(p.parentPipe, syncT{procRun}); err != nil {
return newSystemError(err)
}
sentRun = true
case procError:
// wait for the child process to fully complete and receive an error message
// if one was encoutered
if err := json.NewDecoder(p.parentPipe).Decode(&ierr); err != nil && err != io.EOF {
return newSystemError(err)
}
if ierr != nil {
break loop
}
// Programmer error.
panic("No error following JSON procError payload.")
default:
return newSystemError(fmt.Errorf("invalid JSON synchronisation payload from child"))
}
}
if !sentRun {
return newSystemError(fmt.Errorf("could not synchronise with container process"))
}
if err := syscall.Shutdown(int(p.parentPipe.Fd()), syscall.SHUT_WR); err != nil {
return newSystemError(err)
}
// Must be done after Shutdown so the child will exit and we can wait for it.
if ierr != nil {
p.wait()
return newSystemError(ierr)
}
return nil
}
func (p *initProcess) wait() (*os.ProcessState, error) {
err := p.cmd.Wait()
if err != nil {
return p.cmd.ProcessState, err
}
// we should kill all processes in cgroup when init is died if we use host PID namespace
if p.cmd.SysProcAttr.Cloneflags&syscall.CLONE_NEWPID == 0 {
killCgroupProcesses(p.manager)
}
return p.cmd.ProcessState, nil
}
func (p *initProcess) terminate() error {
if p.cmd.Process == nil {
return nil
}
err := p.cmd.Process.Kill()
if _, werr := p.wait(); err == nil {
err = werr
}
return err
}
func (p *initProcess) startTime() (string, error) {
return system.GetProcessStartTime(p.pid())
}
func (p *initProcess) sendConfig() error {
// send the state to the container's init process then shutdown writes for the parent
return utils.WriteJSON(p.parentPipe, p.config)
}
func (p *initProcess) createNetworkInterfaces() error {
for _, config := range p.config.Config.Networks {
strategy, err := getStrategy(config.Type)
if err != nil {
return err
}
n := &network{
Network: *config,
}
if err := strategy.create(n, p.pid()); err != nil {
return err
}
p.config.Networks = append(p.config.Networks, n)
}
return nil
}
func (p *initProcess) signal(sig os.Signal) error {
s, ok := sig.(syscall.Signal)
if !ok {
return errors.New("os: unsupported signal type")
}
return syscall.Kill(p.pid(), s)
}
func (p *initProcess) setExternalDescriptors(newFds []string) {
p.fds = newFds
}
func getPipeFds(pid int) ([]string, error) {
fds := make([]string, 3)
dirPath := filepath.Join("/proc", strconv.Itoa(pid), "/fd")
for i := 0; i < 3; i++ {
f := filepath.Join(dirPath, strconv.Itoa(i))
target, err := os.Readlink(f)
if err != nil {
return fds, err
}
fds[i] = target
}
return fds, nil
}
// InitializeIO creates pipes for use with the process's STDIO
// and returns the opposite side for each
func (p *Process) InitializeIO(rootuid int) (i *IO, err error) {
var fds []uintptr
i = &IO{}
// cleanup in case of an error
defer func() {
if err != nil {
for _, fd := range fds {
syscall.Close(int(fd))
}
}
}()
// STDIN
r, w, err := os.Pipe()
if err != nil {
return nil, err
}
fds = append(fds, r.Fd(), w.Fd())
p.Stdin, i.Stdin = r, w
// STDOUT
if r, w, err = os.Pipe(); err != nil {
return nil, err
}
fds = append(fds, r.Fd(), w.Fd())
p.Stdout, i.Stdout = w, r
// STDERR
if r, w, err = os.Pipe(); err != nil {
return nil, err
}
fds = append(fds, r.Fd(), w.Fd())
p.Stderr, i.Stderr = w, r
// change ownership of the pipes incase we are in a user namespace
for _, fd := range fds {
if err := syscall.Fchown(int(fd), rootuid, rootuid); err != nil {
return nil, err
}
}
return i, nil
}