8adfbf2dc3
From the comment: // CheckTrailingGarbage tries to read one byte from stdin and exits with a // fatal error if the read returns any data. // This is meant to be called after reading the password, when there is no more // data expected. This helps to catch problems with third-party tools that // interface with gocryptfs.
303 lines
9.9 KiB
Go
303 lines
9.9 KiB
Go
package main
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import (
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"encoding/json"
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"io/ioutil"
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"log/syslog"
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"net"
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"os"
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"os/exec"
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"os/signal"
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"path/filepath"
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"strings"
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"syscall"
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"time"
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"github.com/hanwen/go-fuse/fuse"
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"github.com/hanwen/go-fuse/fuse/nodefs"
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"github.com/hanwen/go-fuse/fuse/pathfs"
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"github.com/rfjakob/gocryptfs/internal/configfile"
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"github.com/rfjakob/gocryptfs/internal/cryptocore"
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"github.com/rfjakob/gocryptfs/internal/ctlsock"
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"github.com/rfjakob/gocryptfs/internal/fusefrontend"
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"github.com/rfjakob/gocryptfs/internal/fusefrontend_reverse"
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"github.com/rfjakob/gocryptfs/internal/readpassword"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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// doMount mounts an encrypted directory.
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// Called from main.
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func doMount(args *argContainer) int {
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// Check mountpoint
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var err error
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args.mountpoint, err = filepath.Abs(flagSet.Arg(1))
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if err != nil {
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tlog.Fatal.Printf("Invalid mountpoint: %v", err)
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os.Exit(ErrExitMountPoint)
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}
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// We cannot mount "/home/user/.cipher" at "/home/user" because the mount
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// will hide ".cipher" also for us.
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if args.cipherdir == args.mountpoint || strings.HasPrefix(args.cipherdir, args.mountpoint+"/") {
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tlog.Fatal.Printf("Mountpoint %q would shadow cipherdir %q, this is not supported",
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args.mountpoint, args.cipherdir)
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os.Exit(ErrExitMountPoint)
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}
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if args.nonempty {
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err = checkDir(args.mountpoint)
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} else {
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err = checkDirEmpty(args.mountpoint)
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}
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if err != nil {
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tlog.Fatal.Printf("Invalid mountpoint: %v", err)
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os.Exit(ErrExitMountPoint)
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}
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// Open control socket early so we can error out before asking the user
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// for the password
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if args.ctlsock != "" {
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// We must use an absolute path because we cd to / when daemonizing.
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// This messes up the delete-on-close logic in the unix socket object.
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args.ctlsock, _ = filepath.Abs(args.ctlsock)
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var sock net.Listener
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sock, err = net.Listen("unix", args.ctlsock)
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if err != nil {
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tlog.Fatal.Printf("ctlsock: %v", err)
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os.Exit(ErrExitMount)
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}
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args._ctlsockFd = sock
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// Close also deletes the socket file
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defer func() {
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err = sock.Close()
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if err != nil {
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tlog.Warn.Print(err)
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}
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}()
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}
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// Get master key (may prompt for the password)
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var masterkey []byte
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var confFile *configfile.ConfFile
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if args.masterkey != "" {
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// "-masterkey"
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masterkey = parseMasterKey(args.masterkey)
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} else if args.zerokey {
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// "-zerokey"
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tlog.Info.Printf("Using all-zero dummy master key.")
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tlog.Info.Printf(tlog.ColorYellow +
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"ZEROKEY MODE PROVIDES NO SECURITY AT ALL AND SHOULD ONLY BE USED FOR TESTING." +
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tlog.ColorReset)
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masterkey = make([]byte, cryptocore.KeyLen)
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} else {
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// Load master key from config file
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// Prompts the user for the password
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masterkey, confFile, err = loadConfig(args)
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if err != nil {
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if args._ctlsockFd != nil {
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// Close the socket file (which also deletes it)
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args._ctlsockFd.Close()
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}
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os.Exit(ErrExitLoadConf)
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}
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readpassword.CheckTrailingGarbage()
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printMasterKey(masterkey)
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}
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// We cannot use JSON for pretty-printing as the fields are unexported
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tlog.Debug.Printf("cli args: %#v", args)
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// Initialize FUSE server
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srv := initFuseFrontend(masterkey, args, confFile)
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tlog.Info.Println(tlog.ColorGreen + "Filesystem mounted and ready." + tlog.ColorReset)
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var paniclog *os.File
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// We have been forked into the background, as evidenced by the set
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// "notifypid".
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if args.notifypid > 0 {
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// Chdir to the root directory so we don't block unmounting the CWD
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os.Chdir("/")
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// Switch to syslog
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if !args.nosyslog {
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paniclog, err = ioutil.TempFile("", "gocryptfs_paniclog.")
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if err != nil {
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tlog.Fatal.Printf("Failed to create gocryptfs_paniclog: %v", err)
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os.Exit(ErrExitMount)
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}
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// Switch all of our logs and the generic logger to syslog
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tlog.Info.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_INFO)
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tlog.Debug.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_DEBUG)
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tlog.Warn.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
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tlog.SwitchLoggerToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
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// Daemons should close all fds (and we don't want to get killed by
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// SIGPIPE if any of those get closed on the other end)
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os.Stdin.Close()
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// Redirect stdout and stderr to /tmp/gocryptfs_paniclog.NNNNNN
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// instead of closing them so users have a chance to get the
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// backtrace on a panic.
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// https://github.com/golang/go/issues/325#issuecomment-66049178
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syscall.Dup2(int(paniclog.Fd()), 1)
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syscall.Dup2(int(paniclog.Fd()), 2)
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}
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// Disconnect from the controlling terminal by creating a new session.
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// This prevents us from getting SIGINT when the user presses Ctrl-C
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// to exit a running script that has called gocryptfs.
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_, err = syscall.Setsid()
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if err != nil {
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tlog.Warn.Printf("Setsid: %v", err)
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}
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// Send SIGUSR1 to our parent
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sendUsr1(args.notifypid)
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}
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// Wait for SIGINT in the background and unmount ourselves if we get it.
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// This prevents a dangling "Transport endpoint is not connected"
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// mountpoint if the user hits CTRL-C.
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handleSigint(srv, args.mountpoint)
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// Jump into server loop. Returns when it gets an umount request from the kernel.
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srv.Serve()
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// Delete empty paniclogs
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if paniclog != nil {
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fi, err := paniclog.Stat()
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if err != nil {
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tlog.Warn.Printf("paniclog fstat error: %v", err)
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} else if fi.Size() > 0 {
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tlog.Warn.Printf("paniclog at %q is not empty (size %d). Not deleting it.",
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paniclog.Name(), fi.Size())
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} else {
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syscall.Unlink(paniclog.Name())
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}
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}
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return 0
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}
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// initFuseFrontend - initialize gocryptfs/fusefrontend
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// Calls os.Exit on errors
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func initFuseFrontend(key []byte, args *argContainer, confFile *configfile.ConfFile) *fuse.Server {
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// Reconciliate CLI and config file arguments into a fusefrontend.Args struct
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// that is passed to the filesystem implementation
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cryptoBackend := cryptocore.BackendGoGCM
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if args.openssl {
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cryptoBackend = cryptocore.BackendOpenSSL
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}
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if args.aessiv {
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cryptoBackend = cryptocore.BackendAESSIV
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}
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frontendArgs := fusefrontend.Args{
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Cipherdir: args.cipherdir,
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Masterkey: key,
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PlaintextNames: args.plaintextnames,
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LongNames: args.longnames,
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CryptoBackend: cryptoBackend,
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ConfigCustom: args._configCustom,
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Raw64: args.raw64,
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NoPrealloc: args.noprealloc,
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}
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// confFile is nil when "-zerokey" or "-masterkey" was used
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if confFile != nil {
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// Settings from the config file override command line args
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frontendArgs.PlaintextNames = confFile.IsFeatureFlagSet(configfile.FlagPlaintextNames)
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frontendArgs.Raw64 = confFile.IsFeatureFlagSet(configfile.FlagRaw64)
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if confFile.IsFeatureFlagSet(configfile.FlagAESSIV) {
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frontendArgs.CryptoBackend = cryptocore.BackendAESSIV
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} else if args.reverse {
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tlog.Fatal.Printf("AES-SIV is required by reverse mode, but not enabled in the config file")
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os.Exit(ErrExitUsage)
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}
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}
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// If allow_other is set and we run as root, try to give newly created files to
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// the right user.
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if args.allow_other && os.Getuid() == 0 {
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frontendArgs.PreserveOwner = true
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}
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jsonBytes, _ := json.MarshalIndent(frontendArgs, "", "\t")
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tlog.Debug.Printf("frontendArgs: %s", string(jsonBytes))
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var finalFs pathfs.FileSystem
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var ctlSockBackend ctlsock.Interface
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if args.reverse {
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fs := fusefrontend_reverse.NewFS(frontendArgs)
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finalFs = fs
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ctlSockBackend = fs
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} else {
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fs := fusefrontend.NewFS(frontendArgs)
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finalFs = fs
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ctlSockBackend = fs
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}
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// We have opened the socket early so that we cannot fail here after
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// asking the user for the password
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if args._ctlsockFd != nil {
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go ctlsock.Serve(args._ctlsockFd, ctlSockBackend)
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}
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pathFsOpts := &pathfs.PathNodeFsOptions{ClientInodes: true}
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pathFs := pathfs.NewPathNodeFs(finalFs, pathFsOpts)
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fuseOpts := &nodefs.Options{
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// These options are to be compatible with libfuse defaults,
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// making benchmarking easier.
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NegativeTimeout: time.Second,
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AttrTimeout: time.Second,
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EntryTimeout: time.Second,
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}
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conn := nodefs.NewFileSystemConnector(pathFs.Root(), fuseOpts)
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var mOpts fuse.MountOptions
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mOpts.AllowOther = false
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if args.allow_other {
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tlog.Info.Printf(tlog.ColorYellow + "The option \"-allow_other\" is set. Make sure the file " +
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"permissions protect your data from unwanted access." + tlog.ColorReset)
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mOpts.AllowOther = true
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// Make the kernel check the file permissions for us
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mOpts.Options = append(mOpts.Options, "default_permissions")
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}
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if args.nonempty {
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mOpts.Options = append(mOpts.Options, "nonempty")
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}
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// Set values shown in "df -T" and friends
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// First column, "Filesystem"
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fsname := args.cipherdir
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if args.fsname != "" {
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fsname = args.fsname
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}
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mOpts.Options = append(mOpts.Options, "fsname="+fsname)
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// Second column, "Type", will be shown as "fuse." + Name
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mOpts.Name = "gocryptfs"
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if args.reverse {
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mOpts.Name += "-reverse"
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}
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// The kernel enforces read-only operation, we just have to pass "ro".
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// Reverse mounts are always read-only.
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if args.ro || args.reverse {
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mOpts.Options = append(mOpts.Options, "ro")
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}
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// Add additional mount options (if any) after the stock ones, so the user has
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// a chance to override them.
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if args.ko != "" {
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parts := strings.Split(args.ko, ",")
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tlog.Debug.Printf("Adding -ko mount options: %v", parts)
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mOpts.Options = append(mOpts.Options, parts...)
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}
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srv, err := fuse.NewServer(conn.RawFS(), args.mountpoint, &mOpts)
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if err != nil {
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tlog.Fatal.Printf("Mount failed: %v", err)
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os.Exit(ErrExitMount)
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}
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srv.SetDebug(args.fusedebug)
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// All FUSE file and directory create calls carry explicit permission
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// information. We need an unrestricted umask to create the files and
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// directories with the requested permissions.
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syscall.Umask(0000)
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return srv
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}
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func handleSigint(srv *fuse.Server, mountpoint string) {
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ch := make(chan os.Signal, 1)
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signal.Notify(ch, os.Interrupt)
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signal.Notify(ch, syscall.SIGTERM)
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go func() {
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<-ch
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err := srv.Unmount()
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if err != nil {
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tlog.Warn.Print(err)
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tlog.Info.Printf("Trying lazy unmount")
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cmd := exec.Command("fusermount", "-u", "-z", mountpoint)
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cmd.Stdout = os.Stdout
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cmd.Stderr = os.Stderr
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cmd.Run()
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}
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os.Exit(1)
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}()
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}
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