aboutsummaryrefslogtreecommitdiff
path: root/pkg/rootlessport/rootlessport_linux.go
blob: c686d80fcc2aeec206cbee5033dbd8dfc6386264 (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
// +build linux

// Package rootlessport provides reexec for RootlessKit-based port forwarder.
//
// init() contains reexec.Register() for ReexecKey .
//
// The reexec requires Config to be provided via stdin.
//
// The reexec writes human-readable error message on stdout on error.
//
// Debug log is printed on stderr.
package rootlessport

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"os/exec"
	"os/signal"

	"github.com/containernetworking/plugins/pkg/ns"
	"github.com/containers/storage/pkg/reexec"
	"github.com/cri-o/ocicni/pkg/ocicni"
	"github.com/pkg/errors"
	rkport "github.com/rootless-containers/rootlesskit/pkg/port"
	rkbuiltin "github.com/rootless-containers/rootlesskit/pkg/port/builtin"
	rkportutil "github.com/rootless-containers/rootlesskit/pkg/port/portutil"
	"github.com/sirupsen/logrus"
	"golang.org/x/sys/unix"
)

const (
	// ReexecKey is the reexec key for the parent process.
	ReexecKey = "containers-rootlessport"
	// reexecChildKey is used internally for the second reexec
	reexecChildKey       = "containers-rootlessport-child"
	reexecChildEnvOpaque = "_CONTAINERS_ROOTLESSPORT_CHILD_OPAQUE"
)

// Config needs to be provided to the process via stdin as a JSON string.
// stdin needs to be closed after the message has been written.
type Config struct {
	Mappings  []ocicni.PortMapping
	NetNSPath string
	ExitFD    int
	ReadyFD   int
	TmpDir    string
}

func init() {
	reexec.Register(ReexecKey, func() {
		if err := parent(); err != nil {
			fmt.Println(err)
			os.Exit(1)
		}
	})
	reexec.Register(reexecChildKey, func() {
		if err := child(); err != nil {
			fmt.Println(err)
			os.Exit(1)
		}
	})

}

func loadConfig(r io.Reader) (*Config, io.ReadCloser, io.WriteCloser, error) {
	stdin, err := ioutil.ReadAll(r)
	if err != nil {
		return nil, nil, nil, err
	}
	var cfg Config
	if err := json.Unmarshal(stdin, &cfg); err != nil {
		return nil, nil, nil, err
	}
	if cfg.NetNSPath == "" {
		return nil, nil, nil, errors.New("missing NetNSPath")
	}
	if cfg.ExitFD <= 0 {
		return nil, nil, nil, errors.New("missing ExitFD")
	}
	exitFile := os.NewFile(uintptr(cfg.ExitFD), "exitfile")
	if exitFile == nil {
		return nil, nil, nil, errors.New("invalid ExitFD")
	}
	if cfg.ReadyFD <= 0 {
		return nil, nil, nil, errors.New("missing ReadyFD")
	}
	readyFile := os.NewFile(uintptr(cfg.ReadyFD), "readyfile")
	if readyFile == nil {
		return nil, nil, nil, errors.New("invalid ReadyFD")
	}
	return &cfg, exitFile, readyFile, nil
}

func parent() error {
	// load config from stdin
	cfg, exitR, readyW, err := loadConfig(os.Stdin)
	if err != nil {
		return err
	}

	exitC := make(chan os.Signal, 1)
	defer close(exitC)

	go func() {
		sigC := make(chan os.Signal, 1)
		signal.Notify(sigC, unix.SIGPIPE)
		defer func() {
			signal.Stop(sigC)
			close(sigC)
		}()

		select {
		case s := <-sigC:
			if s == unix.SIGPIPE {
				if f, err := os.OpenFile("/dev/null", os.O_WRONLY, 0755); err == nil {
					unix.Dup2(int(f.Fd()), 1) // nolint:errcheck
					unix.Dup2(int(f.Fd()), 2) // nolint:errcheck
					f.Close()
				}
			}
		case <-exitC:
		}
	}()

	// create the parent driver
	stateDir, err := ioutil.TempDir(cfg.TmpDir, "rootlessport")
	if err != nil {
		return err
	}
	defer os.RemoveAll(stateDir)
	driver, err := rkbuiltin.NewParentDriver(&logrusWriter{prefix: "parent: "}, stateDir)
	if err != nil {
		return err
	}
	initComplete := make(chan struct{})
	quit := make(chan struct{})
	errCh := make(chan error)
	// start the parent driver. initComplete will be closed when the child connected to the parent.
	logrus.Infof("starting parent driver")
	go func() {
		driverErr := driver.RunParentDriver(initComplete, quit, nil)
		if driverErr != nil {
			logrus.WithError(driverErr).Warn("parent driver exited")
		}
		errCh <- driverErr
		close(errCh)
	}()
	opaque := driver.OpaqueForChild()
	logrus.Infof("opaque=%+v", opaque)
	opaqueJSON, err := json.Marshal(opaque)
	if err != nil {
		return err
	}
	childQuitR, childQuitW, err := os.Pipe()
	if err != nil {
		return err
	}
	defer func() {
		// stop the child
		logrus.Info("stopping child driver")
		if err := childQuitW.Close(); err != nil {
			logrus.WithError(err).Warn("unable to close childQuitW")
		}
	}()

	// reexec the child process in the child netns
	cmd := exec.Command("/proc/self/exe")
	cmd.Args = []string{reexecChildKey}
	cmd.Stdin = childQuitR
	cmd.Stdout = &logrusWriter{prefix: "child"}
	cmd.Stderr = cmd.Stdout
	cmd.Env = append(os.Environ(), reexecChildEnvOpaque+"="+string(opaqueJSON))
	childNS, err := ns.GetNS(cfg.NetNSPath)
	if err != nil {
		return err
	}
	if err := childNS.Do(func(_ ns.NetNS) error {
		logrus.Infof("starting child driver in child netns (%q %v)", cmd.Path, cmd.Args)
		return cmd.Start()
	}); err != nil {
		return err
	}

	childErrCh := make(chan error)
	go func() {
		err := cmd.Wait()
		childErrCh <- err
		close(childErrCh)
	}()

	defer func() {
		if err := unix.Kill(cmd.Process.Pid, unix.SIGTERM); err != nil {
			logrus.WithError(err).Warn("kill child process")
		}
	}()

	logrus.Info("waiting for initComplete")
	// wait for the child to connect to the parent
outer:
	for {
		select {
		case <-initComplete:
			logrus.Infof("initComplete is closed; parent and child established the communication channel")
			break outer
		case err := <-childErrCh:
			if err != nil {
				return err
			}
		case err := <-errCh:
			if err != nil {
				return err
			}
		}
	}

	defer func() {
		logrus.Info("stopping parent driver")
		quit <- struct{}{}
		if err := <-errCh; err != nil {
			logrus.WithError(err).Warn("parent driver returned error on exit")
		}
	}()

	// let parent expose ports
	logrus.Infof("exposing ports %v", cfg.Mappings)
	if err := exposePorts(driver, cfg.Mappings); err != nil {
		return err
	}

	// write and close ReadyFD (convention is same as slirp4netns --ready-fd)
	logrus.Info("ready")
	if _, err := readyW.Write([]byte("1")); err != nil {
		return err
	}
	if err := readyW.Close(); err != nil {
		return err
	}

	// wait for ExitFD to be closed
	logrus.Info("waiting for exitfd to be closed")
	if _, err := ioutil.ReadAll(exitR); err != nil {
		return err
	}
	return nil
}

func exposePorts(pm rkport.Manager, portMappings []ocicni.PortMapping) error {
	ctx := context.TODO()
	for _, i := range portMappings {
		hostIP := i.HostIP
		if hostIP == "" {
			hostIP = "0.0.0.0"
		}
		spec := rkport.Spec{
			Proto:      i.Protocol,
			ParentIP:   hostIP,
			ParentPort: int(i.HostPort),
			ChildPort:  int(i.ContainerPort),
		}
		if err := rkportutil.ValidatePortSpec(spec, nil); err != nil {
			return err
		}
		if _, err := pm.AddPort(ctx, spec); err != nil {
			return err
		}
	}
	return nil
}

func child() error {
	// load the config from the parent
	var opaque map[string]string
	if err := json.Unmarshal([]byte(os.Getenv(reexecChildEnvOpaque)), &opaque); err != nil {
		return err
	}

	// start the child driver
	quit := make(chan struct{})
	errCh := make(chan error)
	go func() {
		d := rkbuiltin.NewChildDriver(os.Stderr)
		dErr := d.RunChildDriver(opaque, quit)
		errCh <- dErr
	}()
	defer func() {
		logrus.Info("stopping child driver")
		quit <- struct{}{}
		if err := <-errCh; err != nil {
			logrus.WithError(err).Warn("child driver returned error on exit")
		}
	}()

	// wait for stdin to be closed
	if _, err := ioutil.ReadAll(os.Stdin); err != nil {
		return err
	}
	return nil
}

type logrusWriter struct {
	prefix string
}

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