package main import ( "bytes" "fmt" "log" "log/syslog" "math" "net" "os" "os/exec" "os/signal" "path" "path/filepath" "runtime" "runtime/debug" "strings" "sync/atomic" "syscall" "time" "github.com/hanwen/go-fuse/v2/fs" "github.com/hanwen/go-fuse/v2/fuse" "github.com/rfjakob/gocryptfs/internal/configfile" "github.com/rfjakob/gocryptfs/internal/contentenc" "github.com/rfjakob/gocryptfs/internal/cryptocore" "github.com/rfjakob/gocryptfs/internal/ctlsocksrv" "github.com/rfjakob/gocryptfs/internal/exitcodes" "github.com/rfjakob/gocryptfs/internal/fusefrontend" "github.com/rfjakob/gocryptfs/internal/fusefrontend_reverse" "github.com/rfjakob/gocryptfs/internal/nametransform" "github.com/rfjakob/gocryptfs/internal/openfiletable" "github.com/rfjakob/gocryptfs/internal/tlog" ) // AfterUnmount is called after the filesystem has been unmounted. // This can be used for cleanup and printing statistics. type AfterUnmounter interface { AfterUnmount() } // doMount mounts an encrypted directory. // Called from main. func doMount(args *argContainer) { // 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(exitcodes.MountPoint) } // 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(exitcodes.MountPoint) } // Reverse-mounting "/foo" at "/foo/mnt" means we would be recursively // encrypting ourselves. if strings.HasPrefix(args.mountpoint, args.cipherdir+"/") { tlog.Fatal.Printf("Mountpoint %q is contained in cipherdir %q, this is not supported", args.mountpoint, args.cipherdir) os.Exit(exitcodes.MountPoint) } if args.nonempty { err = isDir(args.mountpoint) } else if strings.HasPrefix(args.mountpoint, "/dev/fd/") { // Magic fuse fd syntax, do nothing and let go-fuse figure it out. // // See https://github.com/libfuse/libfuse/commit/64e11073b9347fcf9c6d1eea143763ba9e946f70 // and `drop_privileges` in `man mount.fuse3` for background. } else { err = isEmptyDir(args.mountpoint) // OSXFuse will create the mountpoint for us ( https://github.com/rfjakob/gocryptfs/issues/194 ) if runtime.GOOS == "darwin" && os.IsNotExist(err) { tlog.Info.Printf("Mountpoint %q does not exist, but should be created by OSXFuse", args.mountpoint) err = nil } } if err != nil { tlog.Fatal.Printf("Invalid mountpoint: %v", err) os.Exit(exitcodes.MountPoint) } // 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(exitcodes.CtlSock) } args._ctlsockFd = sock // Close also deletes the socket file defer func() { err = sock.Close() if err != nil { tlog.Warn.Printf("ctlsock close: %v", err) } }() } // Initialize gocryptfs (read config file, ask for password, ...) fs, wipeKeys := initFuseFrontend(args) // Try to wipe secret keys from memory after unmount defer wipeKeys() // Initialize go-fuse FUSE server srv := initGoFuse(fs, args) if x, ok := fs.(AfterUnmounter); ok { defer x.AfterUnmount() } tlog.Info.Println(tlog.ColorGreen + "Filesystem mounted and ready." + tlog.ColorReset) // 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 { // 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.Fatal.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_CRIT) tlog.SwitchLoggerToSyslog() // Daemons should redirect stdin, stdout and stderr redirectStdFds() } // 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) } // Increase the open file limit to 4096. This is not essential, so do it after // we have switched to syslog and don't bother the user with warnings. setOpenFileLimit() // 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) // Return memory that was allocated for scrypt (64M by default!) and other // stuff that is no longer needed to the OS debug.FreeOSMemory() // Set up autounmount, if requested. if args.idle > 0 && !args.reverse { // Not being in reverse mode means we always have a forward file system. fwdFs := fs.(*fusefrontend.RootNode) go idleMonitor(args.idle, fwdFs, srv, args.mountpoint) } // Wait for unmount. srv.Wait() } // Based on the EncFS idle monitor: // https://github.com/vgough/encfs/blob/1974b417af189a41ffae4c6feb011d2a0498e437/encfs/main.cpp#L851 // idleMonitor is a function to be run as a thread that checks for // filesystem idleness and unmounts if we've been idle for long enough. const checksDuringTimeoutPeriod = 4 func idleMonitor(idleTimeout time.Duration, fs *fusefrontend.RootNode, srv *fuse.Server, mountpoint string) { // sleepNs is the sleep time between checks, in nanoseconds. sleepNs := contentenc.MinUint64( uint64(idleTimeout/checksDuringTimeoutPeriod), uint64(2*time.Minute)) timeoutCycles := int(math.Ceil(float64(idleTimeout) / float64(sleepNs))) idleCount := 0 idleTime := func() time.Duration { return time.Duration(sleepNs * uint64(idleCount)) } for { // Atomically check whether the flag is 0 and reset it to 1 if so. isIdle := !atomic.CompareAndSwapUint32(&fs.IsIdle, 0, 1) // Any form of current or recent access resets the idle counter. openFileCount := openfiletable.CountOpenFiles() if !isIdle || openFileCount > 0 { idleCount = 0 } else { idleCount++ } tlog.Debug.Printf( "idleMonitor: idle for %v (idleCount = %d, isIdle = %t, open = %d)", idleTime(), idleCount, isIdle, openFileCount) if idleCount > 0 && idleCount%timeoutCycles == 0 { tlog.Info.Printf("idleMonitor: filesystem idle; unmounting: %s", mountpoint) err := srv.Unmount() if err != nil { // We get "Device or resource busy" when a process has its // working directory on the mount. Log the event at Info level // so the user finds out why their filesystem does not get // unmounted. tlog.Info.Printf("idleMonitor: unmount failed: %v. Resetting idle time.", err) idleCount = 0 } } time.Sleep(time.Duration(sleepNs)) } } // setOpenFileLimit tries to increase the open file limit to 4096 (the default hard // limit on Linux). func setOpenFileLimit() { var lim syscall.Rlimit err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim) if err != nil { tlog.Warn.Printf("Getting RLIMIT_NOFILE failed: %v", err) return } if lim.Cur >= 4096 { return } lim.Cur = 4096 err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &lim) if err != nil { tlog.Warn.Printf("Setting RLIMIT_NOFILE to %+v failed: %v", lim, err) // %+v output: "{Cur:4097 Max:4096}" ^ } } // initFuseFrontend - initialize gocryptfs/internal/fusefrontend // Calls os.Exit on errors func initFuseFrontend(args *argContainer) (rootNode fs.InodeEmbedder, wipeKeys func()) { var err error var confFile *configfile.ConfFile // Get the masterkey from the command line if it was specified masterkey := handleArgsMasterkey(args) // Otherwise, load masterkey from config file (normal operation). // Prompts the user for the password. if masterkey == nil { masterkey, confFile, err = loadConfig(args) if err != nil { if args._ctlsockFd != nil { // Close the socket file (which also deletes it) args._ctlsockFd.Close() } exitcodes.Exit(err) } } // 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 } // forceOwner implies allow_other, as documented. // Set this early, so args.allow_other can be relied on below this point. if args._forceOwner != nil { args.allow_other = true } frontendArgs := fusefrontend.Args{ Cipherdir: args.cipherdir, PlaintextNames: args.plaintextnames, LongNames: args.longnames, ConfigCustom: args._configCustom, NoPrealloc: args.noprealloc, SerializeReads: args.serialize_reads, ForceDecode: args.forcedecode, ForceOwner: args._forceOwner, Exclude: args.exclude, ExcludeWildcard: args.excludeWildcard, ExcludeFrom: args.excludeFrom, Suid: args.suid, KernelCache: args.kernel_cache, SharedStorage: args.sharedstorage, } // 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) args.raw64 = confFile.IsFeatureFlagSet(configfile.FlagRaw64) args.hkdf = confFile.IsFeatureFlagSet(configfile.FlagHKDF) if confFile.IsFeatureFlagSet(configfile.FlagAESSIV) { 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(exitcodes.Usage) } } // 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 } // Init crypto backend cCore := cryptocore.New(masterkey, cryptoBackend, contentenc.DefaultIVBits, args.hkdf, args.forcedecode) cEnc := contentenc.New(cCore, contentenc.DefaultBS, args.forcedecode) nameTransform := nametransform.New(cCore.EMECipher, frontendArgs.LongNames, args.raw64, []string(args.badname)) // After the crypto backend is initialized, // we can purge the master key from memory. for i := range masterkey { masterkey[i] = 0 } masterkey = nil // Spawn fusefrontend tlog.Debug.Printf("frontendArgs: %s", tlog.JSONDump(frontendArgs)) if args.reverse { if cryptoBackend != cryptocore.BackendAESSIV { log.Panic("reverse mode must use AES-SIV, everything else is insecure") } rootNode = fusefrontend_reverse.NewRootNode(frontendArgs, cEnc, nameTransform) } else { rootNode = fusefrontend.NewRootNode(frontendArgs, cEnc, nameTransform) } // We have opened the socket early so that we cannot fail here after // asking the user for the password if args._ctlsockFd != nil { go ctlsocksrv.Serve(args._ctlsockFd, rootNode.(ctlsocksrv.Interface)) } return rootNode, func() { cCore.Wipe() } } // initGoFuse calls into go-fuse to mount `rootNode` on `args.mountpoint`. // The mountpoint is ready to use when the functions returns. // On error, it calls os.Exit and does not return. func initGoFuse(rootNode fs.InodeEmbedder, args *argContainer) *fuse.Server { var fuseOpts *fs.Options sec := time.Second if args.sharedstorage { // sharedstorage mode sets all cache timeouts to zero so changes to the // backing shared storage show up immediately. // Hard links are disabled by using automatically incrementing // inode numbers provided by go-fuse. fuseOpts = &fs.Options{ FirstAutomaticIno: 1000, } } else { fuseOpts = &fs.Options{ // These options are to be compatible with libfuse defaults, // making benchmarking easier. NegativeTimeout: &sec, AttrTimeout: &sec, EntryTimeout: &sec, } } fuseOpts.NullPermissions = true // Enable go-fuse warnings fuseOpts.Logger = log.New(os.Stderr, "go-fuse: ", log.Lmicroseconds) fuseOpts.MountOptions = fuse.MountOptions{ // Writes and reads are usually capped at 128kiB on Linux through // the FUSE_MAX_PAGES_PER_REQ kernel constant in fuse_i.h. Our // sync.Pool buffer pools are sized acc. to the default. Users may set // the kernel constant higher, and Synology NAS kernels are known to // have it >128kiB. We cannot handle more than 128kiB, so we tell // the kernel to limit the size explicitly. MaxWrite: fuse.MAX_KERNEL_WRITE, Options: []string{fmt.Sprintf("max_read=%d", fuse.MAX_KERNEL_WRITE)}, Debug: args.fusedebug, } mOpts := &fuseOpts.MountOptions 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.acl { mOpts.EnableAcl = true } if args.forcedecode { tlog.Info.Printf(tlog.ColorYellow + "THE OPTION \"-forcedecode\" IS ACTIVE. GOCRYPTFS WILL RETURN CORRUPT DATA!" + tlog.ColorReset) } // fusermount from libfuse 3.x removed the "nonempty" option and exits // with an error if it sees it. Only add it to the options on libfuse 2.x. if args.nonempty && haveFusermount2() { 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 } fsname2 := strings.Replace(fsname, ",", "_", -1) if fsname2 != fsname { tlog.Warn.Printf("Warning: %q will be displayed as %q in \"df -T\"", fsname, fsname2) fsname = fsname2 } 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" } // Add a volume name if running osxfuse. Otherwise the Finder will show it as // something like "osxfuse Volume 0 (gocryptfs)". if runtime.GOOS == "darwin" { volname := strings.Replace(path.Base(args.mountpoint), ",", "_", -1) mOpts.Options = append(mOpts.Options, "volname="+volname) } // 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") } else if args.rw { mOpts.Options = append(mOpts.Options, "rw") } // If both "nosuid" & "suid", "nodev" & "dev", etc were passed, the safer // option wins. if args.nosuid { mOpts.Options = append(mOpts.Options, "nosuid") } else if args.suid { mOpts.Options = append(mOpts.Options, "suid") } if args.nodev { mOpts.Options = append(mOpts.Options, "nodev") } else if args.dev { mOpts.Options = append(mOpts.Options, "dev") } if args.noexec { mOpts.Options = append(mOpts.Options, "noexec") } else if args.exec { mOpts.Options = append(mOpts.Options, "exec") } // 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 := fs.Mount(args.mountpoint, rootNode, fuseOpts) if err != nil { tlog.Fatal.Printf("fs.Mount failed: %s", strings.TrimSpace(err.Error())) if runtime.GOOS == "darwin" { tlog.Info.Printf("Maybe you should run: /Library/Filesystems/osxfuse.fs/Contents/Resources/load_osxfuse") } os.Exit(exitcodes.FuseNewServer) } // 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 } // haveFusermount2 finds out if the "fusermount" binary is from libfuse 2.x. func haveFusermount2() bool { path, err := exec.LookPath("fusermount") if err != nil { path = "/bin/fusermount" } cmd := exec.Command(path, "-V") var out bytes.Buffer cmd.Stdout = &out err = cmd.Run() if err != nil { tlog.Warn.Printf("warning: haveFusermount2: %v", err) return false } // libfuse 2: fusermount version: 2.9.9 // libfuse 3: fusermount3 version: 3.9.0 v := out.String() if strings.HasPrefix(v, "fusermount version") { return true } return false } 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 unmount(srv, mountpoint) os.Exit(exitcodes.SigInt) }() } // unmount() calls srv.Unmount(), and if that fails, calls "fusermount -u -z" // (lazy unmount). func unmount(srv *fuse.Server, mountpoint string) { err := srv.Unmount() if err != nil { tlog.Warn.Printf("unmount: srv.Unmount returned %v", 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() } } }