aboutsummaryrefslogtreecommitdiff
path: root/libpod/container_copy_linux.go
blob: 38927d69115d2f5471aece499844b7986e66094a (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
//go:build linux
// +build linux

package libpod

import (
	"context"
	"io"
	"os"
	"path/filepath"
	"runtime"
	"strings"

	buildahCopiah "github.com/containers/buildah/copier"
	"github.com/containers/buildah/pkg/chrootuser"
	"github.com/containers/buildah/util"
	"github.com/containers/podman/v4/libpod/define"
	"github.com/containers/podman/v4/pkg/rootless"
	"github.com/containers/storage/pkg/archive"
	"github.com/containers/storage/pkg/idtools"
	"github.com/opencontainers/runtime-spec/specs-go"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	"golang.org/x/sys/unix"
)

func (c *Container) copyFromArchive(ctx context.Context, path string, chown bool, rename map[string]string, reader io.Reader) (func() error, error) {
	var (
		mountPoint   string
		resolvedRoot string
		resolvedPath string
		unmount      func()
		err          error
	)

	// Make sure that "/" copies the *contents* of the mount point and not
	// the directory.
	if path == "/" {
		path = "/."
	}

	// Optimization: only mount if the container is not already.
	if c.state.Mounted {
		mountPoint = c.state.Mountpoint
		unmount = func() {}
	} else {
		// NOTE: make sure to unmount in error paths.
		mountPoint, err = c.mount()
		if err != nil {
			return nil, err
		}
		unmount = func() { c.unmount(false) }
	}

	if c.state.State == define.ContainerStateRunning {
		resolvedRoot = "/"
		resolvedPath = c.pathAbs(path)
	} else {
		resolvedRoot, resolvedPath, err = c.resolvePath(mountPoint, path)
		if err != nil {
			unmount()
			return nil, err
		}
	}

	var idPair *idtools.IDPair
	if chown {
		// Make sure we chown the files to the container's main user and group ID.
		user, err := getContainerUser(c, mountPoint)
		if err != nil {
			unmount()
			return nil, err
		}
		idPair = &idtools.IDPair{UID: int(user.UID), GID: int(user.GID)}
	}

	decompressed, err := archive.DecompressStream(reader)
	if err != nil {
		unmount()
		return nil, err
	}

	logrus.Debugf("Container copy *to* %q (resolved: %q) on container %q (ID: %s)", path, resolvedPath, c.Name(), c.ID())

	return func() error {
		defer unmount()
		defer decompressed.Close()
		putOptions := buildahCopiah.PutOptions{
			UIDMap:     c.config.IDMappings.UIDMap,
			GIDMap:     c.config.IDMappings.GIDMap,
			ChownDirs:  idPair,
			ChownFiles: idPair,
			Rename:     rename,
		}

		return c.joinMountAndExec(ctx,
			func() error {
				return buildahCopiah.Put(resolvedRoot, resolvedPath, putOptions, decompressed)
			},
		)
	}, nil
}

func (c *Container) copyToArchive(ctx context.Context, path string, writer io.Writer) (func() error, error) {
	var (
		mountPoint string
		unmount    func()
		err        error
	)

	// Optimization: only mount if the container is not already.
	if c.state.Mounted {
		mountPoint = c.state.Mountpoint
		unmount = func() {}
	} else {
		// NOTE: make sure to unmount in error paths.
		mountPoint, err = c.mount()
		if err != nil {
			return nil, err
		}
		unmount = func() { c.unmount(false) }
	}

	statInfo, resolvedRoot, resolvedPath, err := c.stat(ctx, mountPoint, path)
	if err != nil {
		unmount()
		return nil, err
	}

	// We optimistically chown to the host user.  In case of a hypothetical
	// container-to-container copy, the reading side will chown back to the
	// container user.
	user, err := getContainerUser(c, mountPoint)
	if err != nil {
		unmount()
		return nil, err
	}
	hostUID, hostGID, err := util.GetHostIDs(
		idtoolsToRuntimeSpec(c.config.IDMappings.UIDMap),
		idtoolsToRuntimeSpec(c.config.IDMappings.GIDMap),
		user.UID,
		user.GID,
	)
	if err != nil {
		unmount()
		return nil, err
	}
	idPair := idtools.IDPair{UID: int(hostUID), GID: int(hostGID)}

	logrus.Debugf("Container copy *from* %q (resolved: %q) on container %q (ID: %s)", path, resolvedPath, c.Name(), c.ID())

	return func() error {
		defer unmount()
		getOptions := buildahCopiah.GetOptions{
			// Unless the specified points to ".", we want to copy the base directory.
			KeepDirectoryNames: statInfo.IsDir && filepath.Base(path) != ".",
			UIDMap:             c.config.IDMappings.UIDMap,
			GIDMap:             c.config.IDMappings.GIDMap,
			ChownDirs:          &idPair,
			ChownFiles:         &idPair,
			Excludes:           []string{"dev", "proc", "sys"},
			// Ignore EPERMs when copying from rootless containers
			// since we cannot read TTY devices.  Those are owned
			// by the host's root and hence "nobody" inside the
			// container's user namespace.
			IgnoreUnreadable: rootless.IsRootless() && c.state.State == define.ContainerStateRunning,
		}
		return c.joinMountAndExec(ctx,
			func() error {
				return buildahCopiah.Get(resolvedRoot, "", getOptions, []string{resolvedPath}, writer)
			},
		)
	}, nil
}

// getContainerUser returns the specs.User and ID mappings of the container.
func getContainerUser(container *Container, mountPoint string) (specs.User, error) {
	userspec := container.config.User

	uid, gid, _, err := chrootuser.GetUser(mountPoint, userspec)
	u := specs.User{
		UID:      uid,
		GID:      gid,
		Username: userspec,
	}

	if !strings.Contains(userspec, ":") {
		groups, err2 := chrootuser.GetAdditionalGroupsForUser(mountPoint, uint64(u.UID))
		if err2 != nil {
			if errors.Cause(err2) != chrootuser.ErrNoSuchUser && err == nil {
				err = err2
			}
		} else {
			u.AdditionalGids = groups
		}
	}

	return u, err
}

// idtoolsToRuntimeSpec converts idtools ID mapping to the one of the runtime spec.
func idtoolsToRuntimeSpec(idMaps []idtools.IDMap) (convertedIDMap []specs.LinuxIDMapping) {
	for _, idmap := range idMaps {
		tempIDMap := specs.LinuxIDMapping{
			ContainerID: uint32(idmap.ContainerID),
			HostID:      uint32(idmap.HostID),
			Size:        uint32(idmap.Size),
		}
		convertedIDMap = append(convertedIDMap, tempIDMap)
	}
	return convertedIDMap
}

// joinMountAndExec executes the specified function `f` inside the container's
// mount and PID namespace.  That allows for having the exact view on the
// container's file system.
//
// Note, if the container is not running `f()` will be executed as is.
func (c *Container) joinMountAndExec(ctx context.Context, f func() error) error {
	if c.state.State != define.ContainerStateRunning {
		return f()
	}

	// Container's running, so we need to execute `f()` inside its mount NS.
	errChan := make(chan error)
	go func() {
		runtime.LockOSThread()

		// Join the mount and PID NS of the container.
		getFD := func(ns LinuxNS) (*os.File, error) {
			nsPath, err := c.namespacePath(ns)
			if err != nil {
				return nil, err
			}
			return os.Open(nsPath)
		}

		mountFD, err := getFD(MountNS)
		if err != nil {
			errChan <- err
			return
		}
		defer mountFD.Close()

		inHostPidNS, err := c.inHostPidNS()
		if err != nil {
			errChan <- errors.Wrap(err, "checking inHostPidNS")
			return
		}
		var pidFD *os.File
		if !inHostPidNS {
			pidFD, err = getFD(PIDNS)
			if err != nil {
				errChan <- err
				return
			}
			defer pidFD.Close()
		}

		if err := unix.Unshare(unix.CLONE_NEWNS); err != nil {
			errChan <- err
			return
		}

		if pidFD != nil {
			if err := unix.Setns(int(pidFD.Fd()), unix.CLONE_NEWPID); err != nil {
				errChan <- err
				return
			}
		}
		if err := unix.Setns(int(mountFD.Fd()), unix.CLONE_NEWNS); err != nil {
			errChan <- err
			return
		}

		// Last but not least, execute the workload.
		errChan <- f()
	}()
	return <-errChan
}