aboutsummaryrefslogtreecommitdiff
path: root/mount.go
blob: 9e66a94fa4b5dbc26bebd99b9d0ce53710d4e89a (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
package main

import (
	"encoding/json"
	"io/ioutil"
	"log/syslog"
	"net"
	"os"
	"os/exec"
	"os/signal"
	"path/filepath"
	"runtime"
	"strings"
	"syscall"
	"time"

	"github.com/hanwen/go-fuse/fuse"
	"github.com/hanwen/go-fuse/fuse/nodefs"
	"github.com/hanwen/go-fuse/fuse/pathfs"

	"github.com/rfjakob/gocryptfs/internal/configfile"
	"github.com/rfjakob/gocryptfs/internal/cryptocore"
	"github.com/rfjakob/gocryptfs/internal/ctlsock"
	"github.com/rfjakob/gocryptfs/internal/fusefrontend"
	"github.com/rfjakob/gocryptfs/internal/fusefrontend_reverse"
	"github.com/rfjakob/gocryptfs/internal/readpassword"
	"github.com/rfjakob/gocryptfs/internal/tlog"
)

// doMount mounts an encrypted directory.
// Called from main.
func doMount(args *argContainer) int {
	// Check mountpoint
	var err error
	args.mountpoint, err = filepath.Abs(flagSet.Arg(1))
	if err != nil {
		tlog.Fatal.Printf("Invalid mountpoint: %v", err)
		os.Exit(ErrExitMountPoint)
	}
	// We cannot mount "/home/user/.cipher" at "/home/user" because the mount
	// will hide ".cipher" also for us.
	if args.cipherdir == args.mountpoint || strings.HasPrefix(args.cipherdir, args.mountpoint+"/") {
		tlog.Fatal.Printf("Mountpoint %q would shadow cipherdir %q, this is not supported",
			args.mountpoint, args.cipherdir)
		os.Exit(ErrExitMountPoint)
	}
	if args.nonempty {
		err = checkDir(args.mountpoint)
	} else {
		err = checkDirEmpty(args.mountpoint)
	}
	if err != nil {
		tlog.Fatal.Printf("Invalid mountpoint: %v", err)
		os.Exit(ErrExitMountPoint)
	}
	// Open control socket early so we can error out before asking the user
	// for the password
	if args.ctlsock != "" {
		// We must use an absolute path because we cd to / when daemonizing.
		// This messes up the delete-on-close logic in the unix socket object.
		args.ctlsock, _ = filepath.Abs(args.ctlsock)
		var sock net.Listener
		sock, err = net.Listen("unix", args.ctlsock)
		if err != nil {
			tlog.Fatal.Printf("ctlsock: %v", err)
			os.Exit(ErrExitMount)
		}
		args._ctlsockFd = sock
		// Close also deletes the socket file
		defer func() {
			err = sock.Close()
			if err != nil {
				tlog.Warn.Print(err)
			}
		}()
	}
	// Get master key (may prompt for the password)
	var masterkey []byte
	var confFile *configfile.ConfFile
	if args.masterkey != "" {
		// "-masterkey"
		masterkey = parseMasterKey(args.masterkey)
	} else if args.zerokey {
		// "-zerokey"
		tlog.Info.Printf("Using all-zero dummy master key.")
		tlog.Info.Printf(tlog.ColorYellow +
			"ZEROKEY MODE PROVIDES NO SECURITY AT ALL AND SHOULD ONLY BE USED FOR TESTING." +
			tlog.ColorReset)
		masterkey = make([]byte, cryptocore.KeyLen)
	} else {
		// Load master key from config file
		// Prompts the user for the password
		masterkey, confFile, err = loadConfig(args)
		if err != nil {
			if args._ctlsockFd != nil {
				// Close the socket file (which also deletes it)
				args._ctlsockFd.Close()
			}
			os.Exit(ErrExitLoadConf)
		}
		readpassword.CheckTrailingGarbage()
		printMasterKey(masterkey)
	}
	// We cannot use JSON for pretty-printing as the fields are unexported
	tlog.Debug.Printf("cli args: %#v", args)
	// Initialize FUSE server
	srv := initFuseFrontend(masterkey, args, confFile)
	tlog.Info.Println(tlog.ColorGreen + "Filesystem mounted and ready." + tlog.ColorReset)
	var paniclog *os.File
	// We have been forked into the background, as evidenced by the set
	// "notifypid".
	if args.notifypid > 0 {
		// Chdir to the root directory so we don't block unmounting the CWD
		os.Chdir("/")
		// Switch to syslog
		if !args.nosyslog {
			paniclog, err = ioutil.TempFile("", "gocryptfs_paniclog.")
			if err != nil {
				tlog.Fatal.Printf("Failed to create gocryptfs_paniclog: %v", err)
				os.Exit(ErrExitMount)
			}
			// Switch all of our logs and the generic logger to syslog
			tlog.Info.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_INFO)
			tlog.Debug.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_DEBUG)
			tlog.Warn.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
			tlog.SwitchLoggerToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
			// Daemons should close all fds (and we don't want to get killed by
			// SIGPIPE if any of those get closed on the other end)
			os.Stdin.Close()
			// Redirect stdout and stderr to /tmp/gocryptfs_paniclog.NNNNNN
			// instead of closing them so users have a chance to get the
			// backtrace on a panic.
			// https://github.com/golang/go/issues/325#issuecomment-66049178
			syscall.Dup2(int(paniclog.Fd()), 1)
			syscall.Dup2(int(paniclog.Fd()), 2)
		}
		// Disconnect from the controlling terminal by creating a new session.
		// This prevents us from getting SIGINT when the user presses Ctrl-C
		// to exit a running script that has called gocryptfs.
		_, err = syscall.Setsid()
		if err != nil {
			tlog.Warn.Printf("Setsid: %v", err)
		}
		// Send SIGUSR1 to our parent
		sendUsr1(args.notifypid)
	}
	// Wait for SIGINT in the background and unmount ourselves if we get it.
	// This prevents a dangling "Transport endpoint is not connected"
	// mountpoint if the user hits CTRL-C.
	handleSigint(srv, args.mountpoint)
	// Jump into server loop. Returns when it gets an umount request from the kernel.
	srv.Serve()
	// Delete empty paniclogs
	if paniclog != nil {
		fi, err := paniclog.Stat()
		if err != nil {
			tlog.Warn.Printf("paniclog fstat error: %v", err)
		} else if fi.Size() > 0 {
			tlog.Warn.Printf("paniclog at %q is not empty (size %d). Not deleting it.",
				paniclog.Name(), fi.Size())
		} else {
			syscall.Unlink(paniclog.Name())
		}
	}
	return 0
}

// initFuseFrontend - initialize gocryptfs/fusefrontend
// Calls os.Exit on errors
func initFuseFrontend(key []byte, args *argContainer, confFile *configfile.ConfFile) *fuse.Server {
	// Reconciliate CLI and config file arguments into a fusefrontend.Args struct
	// that is passed to the filesystem implementation
	cryptoBackend := cryptocore.BackendGoGCM
	if args.openssl {
		cryptoBackend = cryptocore.BackendOpenSSL
	}
	if args.aessiv {
		cryptoBackend = cryptocore.BackendAESSIV
	}
	frontendArgs := fusefrontend.Args{
		Cipherdir:      args.cipherdir,
		Masterkey:      key,
		PlaintextNames: args.plaintextnames,
		LongNames:      args.longnames,
		CryptoBackend:  cryptoBackend,
		ConfigCustom:   args._configCustom,
		Raw64:          args.raw64,
		NoPrealloc:     args.noprealloc,
	}
	// confFile is nil when "-zerokey" or "-masterkey" was used
	if confFile != nil {
		// Settings from the config file override command line args
		frontendArgs.PlaintextNames = confFile.IsFeatureFlagSet(configfile.FlagPlaintextNames)
		frontendArgs.Raw64 = confFile.IsFeatureFlagSet(configfile.FlagRaw64)
		if confFile.IsFeatureFlagSet(configfile.FlagAESSIV) {
			frontendArgs.CryptoBackend = cryptocore.BackendAESSIV
		} else if args.reverse {
			tlog.Fatal.Printf("AES-SIV is required by reverse mode, but not enabled in the config file")
			os.Exit(ErrExitUsage)
		}
	}
	// If allow_other is set and we run as root, try to give newly created files to
	// the right user.
	if args.allow_other && os.Getuid() == 0 {
		frontendArgs.PreserveOwner = true
	}
	jsonBytes, _ := json.MarshalIndent(frontendArgs, "", "\t")
	tlog.Debug.Printf("frontendArgs: %s", string(jsonBytes))
	var finalFs pathfs.FileSystem
	var ctlSockBackend ctlsock.Interface
	if args.reverse {
		fs := fusefrontend_reverse.NewFS(frontendArgs)
		finalFs = fs
		ctlSockBackend = fs
	} else {
		fs := fusefrontend.NewFS(frontendArgs)
		finalFs = fs
		ctlSockBackend = fs
	}
	// We have opened the socket early so that we cannot fail here after
	// asking the user for the password
	if args._ctlsockFd != nil {
		go ctlsock.Serve(args._ctlsockFd, ctlSockBackend)
	}
	pathFsOpts := &pathfs.PathNodeFsOptions{ClientInodes: true}
	pathFs := pathfs.NewPathNodeFs(finalFs, pathFsOpts)
	fuseOpts := &nodefs.Options{
		// These options are to be compatible with libfuse defaults,
		// making benchmarking easier.
		NegativeTimeout: time.Second,
		AttrTimeout:     time.Second,
		EntryTimeout:    time.Second,
	}
	conn := nodefs.NewFileSystemConnector(pathFs.Root(), fuseOpts)
	var mOpts fuse.MountOptions
	mOpts.AllowOther = false
	if args.allow_other {
		tlog.Info.Printf(tlog.ColorYellow + "The option \"-allow_other\" is set. Make sure the file " +
			"permissions protect your data from unwanted access." + tlog.ColorReset)
		mOpts.AllowOther = true
		// Make the kernel check the file permissions for us
		mOpts.Options = append(mOpts.Options, "default_permissions")
	}
	if args.nonempty {
		mOpts.Options = append(mOpts.Options, "nonempty")
	}
	// Set values shown in "df -T" and friends
	// First column, "Filesystem"
	fsname := args.cipherdir
	if args.fsname != "" {
		fsname = args.fsname
	}
	mOpts.Options = append(mOpts.Options, "fsname="+fsname)
	// Second column, "Type", will be shown as "fuse." + Name
	mOpts.Name = "gocryptfs"
	if args.reverse {
		mOpts.Name += "-reverse"
	}
	// The kernel enforces read-only operation, we just have to pass "ro".
	// Reverse mounts are always read-only.
	if args.ro || args.reverse {
		mOpts.Options = append(mOpts.Options, "ro")
	}
	// Add additional mount options (if any) after the stock ones, so the user has
	// a chance to override them.
	if args.ko != "" {
		parts := strings.Split(args.ko, ",")
		tlog.Debug.Printf("Adding -ko mount options: %v", parts)
		mOpts.Options = append(mOpts.Options, parts...)
	}
	srv, err := fuse.NewServer(conn.RawFS(), args.mountpoint, &mOpts)
	if err != nil {
		tlog.Fatal.Printf("Mount failed: %v", err)
		os.Exit(ErrExitMount)
	}
	srv.SetDebug(args.fusedebug)

	// All FUSE file and directory create calls carry explicit permission
	// information. We need an unrestricted umask to create the files and
	// directories with the requested permissions.
	syscall.Umask(0000)

	return srv
}

func handleSigint(srv *fuse.Server, mountpoint string) {
	ch := make(chan os.Signal, 1)
	signal.Notify(ch, os.Interrupt)
	signal.Notify(ch, syscall.SIGTERM)
	go func() {
		<-ch
		err := srv.Unmount()
		if err != nil {
			tlog.Warn.Print(err)
			if runtime.GOOS == "linux" {
				// MacOSX does not support lazy unmount
				tlog.Info.Printf("Trying lazy unmount")
				cmd := exec.Command("fusermount", "-u", "-z", mountpoint)
				cmd.Stdout = os.Stdout
				cmd.Stderr = os.Stderr
				cmd.Run()
			}
		}
		os.Exit(1)
	}()
}