aboutsummaryrefslogtreecommitdiff
path: root/libpod/oci_conmon_attach_linux.go
blob: 155a8fbc3de3fba109a4be458afbbe50c2ad14f0 (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
//go:build linux
// +build linux

package libpod

import (
	"fmt"
	"io"
	"net"
	"os"
	"path/filepath"
	"syscall"

	"github.com/containers/common/pkg/config"
	"github.com/containers/podman/v4/libpod/define"
	"github.com/containers/podman/v4/pkg/errorhandling"
	"github.com/containers/podman/v4/pkg/kubeutils"
	"github.com/containers/podman/v4/utils"
	"github.com/moby/term"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	"golang.org/x/sys/unix"
)

/* Sync with stdpipe_t in conmon.c */
const (
	AttachPipeStdin  = 1
	AttachPipeStdout = 2
	AttachPipeStderr = 3
)

func openUnixSocket(path string) (*net.UnixConn, error) {
	fd, err := unix.Open(path, unix.O_PATH, 0)
	if err != nil {
		return nil, err
	}
	defer unix.Close(fd)
	return net.DialUnix("unixpacket", nil, &net.UnixAddr{Name: fmt.Sprintf("/proc/self/fd/%d", fd), Net: "unixpacket"})
}

// Attach to the given container.
// Does not check if state is appropriate.
// started is only required if startContainer is true.
func (r *ConmonOCIRuntime) Attach(c *Container, params *AttachOptions) error {
	passthrough := c.LogDriver() == define.PassthroughLogging

	if params == nil || params.Streams == nil {
		return errors.Wrapf(define.ErrInternal, "must provide parameters to Attach")
	}

	if !params.Streams.AttachOutput && !params.Streams.AttachError && !params.Streams.AttachInput && !passthrough {
		return errors.Wrapf(define.ErrInvalidArg, "must provide at least one stream to attach to")
	}
	if params.Start && params.Started == nil {
		return errors.Wrapf(define.ErrInternal, "started chan not passed when startContainer set")
	}

	keys := config.DefaultDetachKeys
	if params.DetachKeys != nil {
		keys = *params.DetachKeys
	}

	detachKeys, err := processDetachKeys(keys)
	if err != nil {
		return err
	}

	var conn *net.UnixConn
	if !passthrough {
		logrus.Debugf("Attaching to container %s", c.ID())

		// If we have a resize, do it.
		if params.InitialSize != nil {
			if err := r.AttachResize(c, *params.InitialSize); err != nil {
				return err
			}
		}

		attachSock, err := c.AttachSocketPath()
		if err != nil {
			return err
		}

		conn, err = openUnixSocket(attachSock)
		if err != nil {
			return errors.Wrapf(err, "failed to connect to container's attach socket: %v", attachSock)
		}
		defer func() {
			if err := conn.Close(); err != nil {
				logrus.Errorf("unable to close socket: %q", err)
			}
		}()
	}

	// If starting was requested, start the container and notify when that's
	// done.
	if params.Start {
		if err := c.start(); err != nil {
			return err
		}
		params.Started <- true
	}

	if passthrough {
		return nil
	}

	receiveStdoutError, stdinDone := setupStdioChannels(params.Streams, conn, detachKeys)
	if params.AttachReady != nil {
		params.AttachReady <- true
	}
	return readStdio(conn, params.Streams, receiveStdoutError, stdinDone)
}

// Attach to the given container's exec session
// attachFd and startFd must be open file descriptors
// attachFd must be the output side of the fd. attachFd is used for two things:
//  conmon will first send a nonce value across the pipe indicating it has set up its side of the console socket
//    this ensures attachToExec gets all of the output of the called process
//  conmon will then send the exit code of the exec process, or an error in the exec session
// startFd must be the input side of the fd.
// newSize resizes the tty to this size before the process is started, must be nil if the exec session has no tty
//   conmon will wait to start the exec session until the parent process has setup the console socket.
//   Once attachToExec successfully attaches to the console socket, the child conmon process responsible for calling runtime exec
//     will read from the output side of start fd, thus learning to start the child process.
// Thus, the order goes as follow:
// 1. conmon parent process sets up its console socket. sends on attachFd
// 2. attachToExec attaches to the console socket after reading on attachFd and resizes the tty
// 3. child waits on startFd for attachToExec to attach to said console socket
// 4. attachToExec sends on startFd, signalling it has attached to the socket and child is ready to go
// 5. child receives on startFd, runs the runtime exec command
// attachToExec is responsible for closing startFd and attachFd
func (c *Container) attachToExec(streams *define.AttachStreams, keys *string, sessionID string, startFd, attachFd *os.File, newSize *define.TerminalSize) error {
	if !streams.AttachOutput && !streams.AttachError && !streams.AttachInput {
		return errors.Wrapf(define.ErrInvalidArg, "must provide at least one stream to attach to")
	}
	if startFd == nil || attachFd == nil {
		return errors.Wrapf(define.ErrInvalidArg, "start sync pipe and attach sync pipe must be defined for exec attach")
	}

	defer errorhandling.CloseQuiet(startFd)
	defer errorhandling.CloseQuiet(attachFd)

	detachString := config.DefaultDetachKeys
	if keys != nil {
		detachString = *keys
	}
	detachKeys, err := processDetachKeys(detachString)
	if err != nil {
		return err
	}

	logrus.Debugf("Attaching to container %s exec session %s", c.ID(), sessionID)

	// set up the socket path, such that it is the correct length and location for exec
	sockPath, err := c.execAttachSocketPath(sessionID)
	if err != nil {
		return err
	}

	// 2: read from attachFd that the parent process has set up the console socket
	if _, err := readConmonPipeData(c.ociRuntime.Name(), attachFd, ""); err != nil {
		return err
	}

	// resize before we start the container process
	if newSize != nil {
		err = c.ociRuntime.ExecAttachResize(c, sessionID, *newSize)
		if err != nil {
			logrus.Warnf("Resize failed: %v", err)
		}
	}

	// 2: then attach
	conn, err := openUnixSocket(sockPath)
	if err != nil {
		return errors.Wrapf(err, "failed to connect to container's attach socket: %v", sockPath)
	}
	defer func() {
		if err := conn.Close(); err != nil {
			logrus.Errorf("Unable to close socket: %q", err)
		}
	}()

	// start listening on stdio of the process
	receiveStdoutError, stdinDone := setupStdioChannels(streams, conn, detachKeys)

	// 4: send start message to child
	if err := writeConmonPipeData(startFd); err != nil {
		return err
	}

	return readStdio(conn, streams, receiveStdoutError, stdinDone)
}

func processDetachKeys(keys string) ([]byte, error) {
	// Check the validity of the provided keys first
	if len(keys) == 0 {
		return []byte{}, nil
	}
	detachKeys, err := term.ToBytes(keys)
	if err != nil {
		return nil, errors.Wrapf(err, "invalid detach keys")
	}
	return detachKeys, nil
}

func registerResizeFunc(resize <-chan define.TerminalSize, bundlePath string) {
	kubeutils.HandleResizing(resize, func(size define.TerminalSize) {
		controlPath := filepath.Join(bundlePath, "ctl")
		controlFile, err := os.OpenFile(controlPath, unix.O_WRONLY, 0)
		if err != nil {
			logrus.Debugf("Could not open ctl file: %v", err)
			return
		}
		defer controlFile.Close()

		logrus.Debugf("Received a resize event: %+v", size)
		if _, err = fmt.Fprintf(controlFile, "%d %d %d\n", 1, size.Height, size.Width); err != nil {
			logrus.Warnf("Failed to write to control file to resize terminal: %v", err)
		}
	})
}

func setupStdioChannels(streams *define.AttachStreams, conn *net.UnixConn, detachKeys []byte) (chan error, chan error) {
	receiveStdoutError := make(chan error)
	go func() {
		receiveStdoutError <- redirectResponseToOutputStreams(streams.OutputStream, streams.ErrorStream, streams.AttachOutput, streams.AttachError, conn)
	}()

	stdinDone := make(chan error)
	go func() {
		var err error
		if streams.AttachInput {
			_, err = utils.CopyDetachable(conn, streams.InputStream, detachKeys)
		}
		stdinDone <- err
	}()

	return receiveStdoutError, stdinDone
}

func redirectResponseToOutputStreams(outputStream, errorStream io.Writer, writeOutput, writeError bool, conn io.Reader) error {
	var err error
	buf := make([]byte, 8192+1) /* Sync with conmon STDIO_BUF_SIZE */
	for {
		nr, er := conn.Read(buf)
		if nr > 0 {
			var dst io.Writer
			var doWrite bool
			switch buf[0] {
			case AttachPipeStdout:
				dst = outputStream
				doWrite = writeOutput
			case AttachPipeStderr:
				dst = errorStream
				doWrite = writeError
			default:
				logrus.Infof("Received unexpected attach type %+d", buf[0])
			}
			if dst == nil {
				return errors.New("output destination cannot be nil")
			}

			if doWrite {
				nw, ew := dst.Write(buf[1:nr])
				if ew != nil {
					err = ew
					break
				}
				if nr != nw+1 {
					err = io.ErrShortWrite
					break
				}
			}
		}
		if errors.Is(er, io.EOF) || errors.Is(er, syscall.ECONNRESET) {
			break
		}
		if er != nil {
			err = er
			break
		}
	}
	return err
}

func readStdio(conn *net.UnixConn, streams *define.AttachStreams, receiveStdoutError, stdinDone chan error) error {
	var err error
	select {
	case err = <-receiveStdoutError:
		if err := conn.CloseWrite(); err != nil {
			logrus.Errorf("Failed to close stdin: %v", err)
		}
		return err
	case err = <-stdinDone:
		if err == define.ErrDetach {
			if err := conn.CloseWrite(); err != nil {
				logrus.Errorf("Failed to close stdin: %v", err)
			}
			return err
		}
		if err == nil {
			// copy stdin is done, close it
			if connErr := conn.CloseWrite(); connErr != nil {
				logrus.Errorf("Unable to close conn: %v", connErr)
			}
		}
		if streams.AttachOutput || streams.AttachError {
			return <-receiveStdoutError
		}
	}
	return nil
}