aboutsummaryrefslogtreecommitdiff
path: root/pkg/specgen/generate/config_linux.go
blob: f4cf0c704889aa4309cd84c444e5cc09b3edda3d (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
315
316
317
318
319
320
321
322
323
324
325
326
327
package generate

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"

	"github.com/containers/libpod/pkg/rootless"
	"github.com/opencontainers/runc/libcontainer/configs"
	"github.com/opencontainers/runc/libcontainer/devices"
	spec "github.com/opencontainers/runtime-spec/specs-go"
	"github.com/opencontainers/runtime-tools/generate"
	"github.com/pkg/errors"
	"golang.org/x/sys/unix"
)

func u32Ptr(i int64) *uint32     { u := uint32(i); return &u }
func fmPtr(i int64) *os.FileMode { fm := os.FileMode(i); return &fm }

// Device transforms a libcontainer configs.Device to a specs.LinuxDevice object.
func Device(d *configs.Device) spec.LinuxDevice {
	return spec.LinuxDevice{
		Type:     string(d.Type),
		Path:     d.Path,
		Major:    d.Major,
		Minor:    d.Minor,
		FileMode: fmPtr(int64(d.FileMode)),
		UID:      u32Ptr(int64(d.Uid)),
		GID:      u32Ptr(int64(d.Gid)),
	}
}

func addPrivilegedDevices(g *generate.Generator) error {
	hostDevices, err := getDevices("/dev")
	if err != nil {
		return err
	}
	g.ClearLinuxDevices()

	if rootless.IsRootless() {
		mounts := make(map[string]interface{})
		for _, m := range g.Mounts() {
			mounts[m.Destination] = true
		}
		newMounts := []spec.Mount{}
		for _, d := range hostDevices {
			devMnt := spec.Mount{
				Destination: d.Path,
				Type:        TypeBind,
				Source:      d.Path,
				Options:     []string{"slave", "nosuid", "noexec", "rw", "rbind"},
			}
			if d.Path == "/dev/ptmx" || strings.HasPrefix(d.Path, "/dev/tty") {
				continue
			}
			if _, found := mounts[d.Path]; found {
				continue
			}
			st, err := os.Stat(d.Path)
			if err != nil {
				if err == unix.EPERM {
					continue
				}
				return errors.Wrapf(err, "stat %s", d.Path)
			}
			// Skip devices that the user has not access to.
			if st.Mode()&0007 == 0 {
				continue
			}
			newMounts = append(newMounts, devMnt)
		}
		g.Config.Mounts = append(newMounts, g.Config.Mounts...)
		if g.Config.Linux.Resources != nil {
			g.Config.Linux.Resources.Devices = nil
		}
	} else {
		for _, d := range hostDevices {
			g.AddDevice(Device(d))
		}
		// Add resources device - need to clear the existing one first.
		if g.Config.Linux.Resources != nil {
			g.Config.Linux.Resources.Devices = nil
		}
		g.AddLinuxResourcesDevice(true, "", nil, nil, "rwm")
	}

	return nil
}

// DevicesFromPath computes a list of devices
func DevicesFromPath(g *generate.Generator, devicePath string) error {
	devs := strings.Split(devicePath, ":")
	resolvedDevicePath := devs[0]
	// check if it is a symbolic link
	if src, err := os.Lstat(resolvedDevicePath); err == nil && src.Mode()&os.ModeSymlink == os.ModeSymlink {
		if linkedPathOnHost, err := filepath.EvalSymlinks(resolvedDevicePath); err == nil {
			resolvedDevicePath = linkedPathOnHost
		}
	}
	st, err := os.Stat(resolvedDevicePath)
	if err != nil {
		return errors.Wrapf(err, "cannot stat %s", devicePath)
	}
	if st.IsDir() {
		found := false
		src := resolvedDevicePath
		dest := src
		var devmode string
		if len(devs) > 1 {
			if len(devs[1]) > 0 && devs[1][0] == '/' {
				dest = devs[1]
			} else {
				devmode = devs[1]
			}
		}
		if len(devs) > 2 {
			if devmode != "" {
				return errors.Wrapf(unix.EINVAL, "invalid device specification %s", devicePath)
			}
			devmode = devs[2]
		}

		// mount the internal devices recursively
		if err := filepath.Walk(resolvedDevicePath, func(dpath string, f os.FileInfo, e error) error {

			if f.Mode()&os.ModeDevice == os.ModeDevice {
				found = true
				device := fmt.Sprintf("%s:%s", dpath, filepath.Join(dest, strings.TrimPrefix(dpath, src)))
				if devmode != "" {
					device = fmt.Sprintf("%s:%s", device, devmode)
				}
				if err := addDevice(g, device); err != nil {
					return errors.Wrapf(err, "failed to add %s device", dpath)
				}
			}
			return nil
		}); err != nil {
			return err
		}
		if !found {
			return errors.Wrapf(unix.EINVAL, "no devices found in %s", devicePath)
		}
		return nil
	}

	return addDevice(g, strings.Join(append([]string{resolvedDevicePath}, devs[1:]...), ":"))
}

func BlockAccessToKernelFilesystems(privileged, pidModeIsHost bool, g *generate.Generator) {
	if !privileged {
		for _, mp := range []string{
			"/proc/acpi",
			"/proc/kcore",
			"/proc/keys",
			"/proc/latency_stats",
			"/proc/timer_list",
			"/proc/timer_stats",
			"/proc/sched_debug",
			"/proc/scsi",
			"/sys/firmware",
			"/sys/fs/selinux",
		} {
			g.AddLinuxMaskedPaths(mp)
		}

		if pidModeIsHost && rootless.IsRootless() {
			return
		}

		for _, rp := range []string{
			"/proc/asound",
			"/proc/bus",
			"/proc/fs",
			"/proc/irq",
			"/proc/sys",
			"/proc/sysrq-trigger",
		} {
			g.AddLinuxReadonlyPaths(rp)
		}
	}
}

// based on getDevices from runc (libcontainer/devices/devices.go)
func getDevices(path string) ([]*configs.Device, error) {
	files, err := ioutil.ReadDir(path)
	if err != nil {
		if rootless.IsRootless() && os.IsPermission(err) {
			return nil, nil
		}
		return nil, err
	}
	out := []*configs.Device{}
	for _, f := range files {
		switch {
		case f.IsDir():
			switch f.Name() {
			// ".lxc" & ".lxd-mounts" added to address https://github.com/lxc/lxd/issues/2825
			case "pts", "shm", "fd", "mqueue", ".lxc", ".lxd-mounts":
				continue
			default:
				sub, err := getDevices(filepath.Join(path, f.Name()))
				if err != nil {
					return nil, err
				}
				if sub != nil {
					out = append(out, sub...)
				}
				continue
			}
		case f.Name() == "console":
			continue
		}
		device, err := devices.DeviceFromPath(filepath.Join(path, f.Name()), "rwm")
		if err != nil {
			if err == devices.ErrNotADevice {
				continue
			}
			if os.IsNotExist(err) {
				continue
			}
			return nil, err
		}
		out = append(out, device)
	}
	return out, nil
}

func addDevice(g *generate.Generator, device string) error {
	src, dst, permissions, err := ParseDevice(device)
	if err != nil {
		return err
	}
	dev, err := devices.DeviceFromPath(src, permissions)
	if err != nil {
		return errors.Wrapf(err, "%s is not a valid device", src)
	}
	if rootless.IsRootless() {
		if _, err := os.Stat(src); err != nil {
			if os.IsNotExist(err) {
				return errors.Wrapf(err, "the specified device %s doesn't exist", src)
			}
			return errors.Wrapf(err, "stat device %s exist", src)
		}
		perm := "ro"
		if strings.Contains(permissions, "w") {
			perm = "rw"
		}
		devMnt := spec.Mount{
			Destination: dst,
			Type:        TypeBind,
			Source:      src,
			Options:     []string{"slave", "nosuid", "noexec", perm, "rbind"},
		}
		g.Config.Mounts = append(g.Config.Mounts, devMnt)
		return nil
	}
	dev.Path = dst
	linuxdev := spec.LinuxDevice{
		Path:     dev.Path,
		Type:     string(dev.Type),
		Major:    dev.Major,
		Minor:    dev.Minor,
		FileMode: &dev.FileMode,
		UID:      &dev.Uid,
		GID:      &dev.Gid,
	}
	g.AddDevice(linuxdev)
	g.AddLinuxResourcesDevice(true, string(dev.Type), &dev.Major, &dev.Minor, dev.Permissions)
	return nil
}

// ParseDevice parses device mapping string to a src, dest & permissions string
func ParseDevice(device string) (string, string, string, error) { //nolint
	src := ""
	dst := ""
	permissions := "rwm"
	arr := strings.Split(device, ":")
	switch len(arr) {
	case 3:
		if !IsValidDeviceMode(arr[2]) {
			return "", "", "", fmt.Errorf("invalid device mode: %s", arr[2])
		}
		permissions = arr[2]
		fallthrough
	case 2:
		if IsValidDeviceMode(arr[1]) {
			permissions = arr[1]
		} else {
			if arr[1][0] != '/' {
				return "", "", "", fmt.Errorf("invalid device mode: %s", arr[1])
			}
			dst = arr[1]
		}
		fallthrough
	case 1:
		src = arr[0]
	default:
		return "", "", "", fmt.Errorf("invalid device specification: %s", device)
	}

	if dst == "" {
		dst = src
	}
	return src, dst, permissions, nil
}

// IsValidDeviceMode checks if the mode for device is valid or not.
// IsValid mode is a composition of r (read), w (write), and m (mknod).
func IsValidDeviceMode(mode string) bool {
	var legalDeviceMode = map[rune]bool{
		'r': true,
		'w': true,
		'm': true,
	}
	if mode == "" {
		return false
	}
	for _, c := range mode {
		if !legalDeviceMode[c] {
			return false
		}
		legalDeviceMode[c] = false
	}
	return true
}