libgocryptfs/main.go

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package main
import (
"flag"
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"fmt"
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"os"
"os/exec"
"os/signal"
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"path/filepath"
"runtime"
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"runtime/pprof"
"syscall"
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"time"
"github.com/rfjakob/gocryptfs/cryptfs"
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"github.com/rfjakob/gocryptfs/pathfs_frontend"
"github.com/hanwen/go-fuse/fuse"
"github.com/hanwen/go-fuse/fuse/nodefs"
"github.com/hanwen/go-fuse/fuse/pathfs"
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)
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const (
PROGRAM_NAME = "gocryptfs"
// Exit codes
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ERREXIT_USAGE = 1
ERREXIT_MOUNT = 3
ERREXIT_CIPHERDIR = 6
ERREXIT_INIT = 7
ERREXIT_LOADCONF = 8
ERREXIT_PASSWORD = 9
ERREXIT_MOUNTPOINT = 10
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)
type argContainer struct {
debug, init, zerokey, fusedebug, openssl, passwd, foreground, version,
plaintextnames, quiet, diriv bool
masterkey, mountpoint, cipherdir, cpuprofile, config, extpass string
notifypid, scryptn int
}
var flagSet *flag.FlagSet
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// GitVersion will be set by the build script "build.bash"
var GitVersion = "[version not set - please compile using ./build.bash]"
func initDir(args *argContainer) {
err := checkDirEmpty(args.cipherdir)
if err != nil {
fmt.Printf("Invalid CIPHERDIR: %v\n", err)
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os.Exit(ERREXIT_INIT)
}
// Create gocryptfs.diriv in the root dir
err = cryptfs.WriteDirIV(args.cipherdir)
if err != nil {
fmt.Println(err)
os.Exit(ERREXIT_INIT)
}
// Create gocryptfs.conf
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cryptfs.Info.Printf("Choose a password for protecting your files.\n")
password := readPasswordTwice(args.extpass)
err = cryptfs.CreateConfFile(args.config, password, args.plaintextnames, args.scryptn)
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if err != nil {
fmt.Println(err)
os.Exit(ERREXIT_INIT)
}
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cryptfs.Info.Printf("The filesystem is now ready for mounting.\n")
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os.Exit(0)
}
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func usageText() {
printVersion()
fmt.Printf("\n")
fmt.Printf("Usage: %s -init|-passwd [OPTIONS] CIPHERDIR\n", PROGRAM_NAME)
fmt.Printf(" or %s [OPTIONS] CIPHERDIR MOUNTPOINT\n", PROGRAM_NAME)
fmt.Printf("\nOptions:\n")
flagSet.PrintDefaults()
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}
// loadConfig - load the config file "filename", prompting the user for the password
func loadConfig(args *argContainer) (masterkey []byte, confFile *cryptfs.ConfFile) {
// Check if the file exists at all before prompting for a password
_, err := os.Stat(args.config)
if err != nil {
fmt.Println(err)
os.Exit(ERREXIT_LOADCONF)
}
fmt.Printf("Password: ")
pw := readPassword(args.extpass)
cryptfs.Info.Printf("Decrypting master key... ")
cryptfs.Warn.Disable() // Silence DecryptBlock() error messages on incorrect password
masterkey, confFile, err = cryptfs.LoadConfFile(args.config, pw)
cryptfs.Warn.Enable()
if err != nil {
fmt.Println(err)
fmt.Println("Wrong password.")
os.Exit(ERREXIT_LOADCONF)
}
cryptfs.Info.Printf("done.\n")
return masterkey, confFile
}
// changePassword - change the password of config file "filename"
func changePassword(args *argContainer) {
masterkey, confFile := loadConfig(args)
fmt.Printf("Please enter your new password.\n")
newPw := readPasswordTwice(args.extpass)
confFile.EncryptKey(masterkey, newPw, confFile.ScryptObject.LogN())
err := confFile.WriteFile()
if err != nil {
fmt.Println(err)
os.Exit(ERREXIT_INIT)
}
cryptfs.Info.Printf("Password changed.\n")
os.Exit(0)
}
// printVersion - print a version string like
// "gocryptfs v0.3.1-31-g6736212-dirty; on-disk format 2"
func printVersion() {
fmt.Printf("%s %s; on-disk format %d\n", PROGRAM_NAME, GitVersion, cryptfs.HEADER_CURRENT_VERSION)
}
func main() {
runtime.GOMAXPROCS(4)
var err error
var args argContainer
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// Parse command line arguments
flagSet = flag.NewFlagSet(PROGRAM_NAME, flag.ExitOnError)
flagSet.Usage = usageText
flagSet.BoolVar(&args.debug, "debug", false, "Enable debug output")
flagSet.BoolVar(&args.fusedebug, "fusedebug", false, "Enable fuse library debug output")
flagSet.BoolVar(&args.init, "init", false, "Initialize encrypted directory")
flagSet.BoolVar(&args.zerokey, "zerokey", false, "Use all-zero dummy master key")
flagSet.BoolVar(&args.openssl, "openssl", true, "Use OpenSSL instead of built-in Go crypto")
flagSet.BoolVar(&args.passwd, "passwd", false, "Change password")
flagSet.BoolVar(&args.foreground, "f", false, "Stay in the foreground")
flagSet.BoolVar(&args.version, "version", false, "Print version and exit")
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flagSet.BoolVar(&args.plaintextnames, "plaintextnames", false, "Do not encrypt "+
"file names")
flagSet.BoolVar(&args.quiet, "q", false, "Quiet - silence informational messages")
flagSet.BoolVar(&args.diriv, "diriv", true, "Use per-directory file name IV")
flagSet.StringVar(&args.masterkey, "masterkey", "", "Mount with explicit master key")
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flagSet.StringVar(&args.cpuprofile, "cpuprofile", "", "Write cpu profile to specified file")
flagSet.StringVar(&args.config, "config", "", "Use specified config file instead of CIPHERDIR/gocryptfs.conf")
flagSet.StringVar(&args.extpass, "extpass", "", "Use external program for the password prompt")
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flagSet.IntVar(&args.notifypid, "notifypid", 0, "Send USR1 to the specified process after "+
"successful mount - used internally for daemonization")
flagSet.IntVar(&args.scryptn, "scryptn", cryptfs.SCRYPT_DEFAULT_LOGN, "scrypt cost parameter logN. "+
"Setting this to a lower value speeds up mounting but makes the password susceptible to brute-force attacks")
flagSet.Parse(os.Args[1:])
// Fork a child into the background if "-f" is not set and we are mounting a filesystem
if !args.foreground && flagSet.NArg() == 2 {
forkChild() // does not return
}
// "-v"
if args.version {
printVersion()
os.Exit(0)
}
if args.debug {
cryptfs.Debug.Enable()
cryptfs.Debug.Printf("Debug output enabled\n")
}
// Every operation below requires CIPHERDIR. Check that we have it.
if flagSet.NArg() >= 1 {
args.cipherdir, _ = filepath.Abs(flagSet.Arg(0))
err := checkDir(args.cipherdir)
if err != nil {
fmt.Printf("Invalid CIPHERDIR: %v\n", err)
os.Exit(ERREXIT_CIPHERDIR)
}
} else {
usageText()
os.Exit(ERREXIT_USAGE)
}
// "-q"
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if args.quiet {
cryptfs.Info.Disable()
}
// "-config"
if args.config != "" {
args.config, err = filepath.Abs(args.config)
if err != nil {
fmt.Printf("Invalid \"-config\" setting: %v\n", err)
}
cryptfs.Info.Printf("Using config file at custom location %s\n", args.config)
} else {
args.config = filepath.Join(args.cipherdir, cryptfs.ConfDefaultName)
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}
// "-cpuprofile"
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if args.cpuprofile != "" {
f, err := os.Create(args.cpuprofile)
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if err != nil {
fmt.Println(err)
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os.Exit(ERREXIT_INIT)
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}
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cryptfs.Info.Printf("Writing CPU profile to %s\n", args.cpuprofile)
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pprof.StartCPUProfile(f)
defer pprof.StopCPUProfile()
}
// "-openssl"
if args.openssl == false {
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cryptfs.Info.Printf("Openssl disabled\n")
}
// Operation flags: init, passwd or mount
// "-init"
if args.init {
if flagSet.NArg() > 1 {
fmt.Printf("Usage: %s -init [OPTIONS] CIPHERDIR\n", PROGRAM_NAME)
os.Exit(ERREXIT_USAGE)
}
initDir(&args) // does not return
}
// "-passwd"
if args.passwd {
if flagSet.NArg() > 1 {
fmt.Printf("Usage: %s -passwd [OPTIONS] CIPHERDIR\n", PROGRAM_NAME)
os.Exit(ERREXIT_USAGE)
}
changePassword(&args) // does not return
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}
// Mount
// Check mountpoint
if flagSet.NArg() != 2 {
usageText()
os.Exit(ERREXIT_USAGE)
}
args.mountpoint, err = filepath.Abs(flagSet.Arg(1))
if err != nil {
fmt.Printf("Invalid MOUNTPOINT: %v\n", err)
os.Exit(ERREXIT_MOUNTPOINT)
}
err = checkDirEmpty(args.mountpoint)
if err != nil {
fmt.Printf("Invalid MOUNTPOINT: %v\n", err)
os.Exit(ERREXIT_MOUNTPOINT)
}
// Get master key
var masterkey []byte
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var confFile *cryptfs.ConfFile
if args.masterkey != "" {
// "-masterkey"
cryptfs.Info.Printf("Using explicit master key.\n")
masterkey = parseMasterKey(args.masterkey)
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cryptfs.Info.Printf("THE MASTER KEY IS VISIBLE VIA \"ps -auxwww\", ONLY USE THIS MODE FOR EMERGENCIES.\n")
} else if args.zerokey {
// "-zerokey"
cryptfs.Info.Printf("Using all-zero dummy master key.\n")
cryptfs.Info.Printf("ZEROKEY MODE PROVIDES NO SECURITY AT ALL AND SHOULD ONLY BE USED FOR TESTING.\n")
masterkey = make([]byte, cryptfs.KEY_LEN)
} else {
// Load master key from config file
masterkey, confFile = loadConfig(&args)
printMasterKey(masterkey)
}
// Initialize FUSE server
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cryptfs.Debug.Printf("args: %v\n", args)
srv := pathfsFrontend(masterkey, args, confFile)
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cryptfs.Info.Println("Filesystem ready.")
// We are ready - send USR1 signal to our parent
if args.notifypid > 0 {
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.
handleSigint(srv, args.mountpoint)
// Jump into server loop. Returns when it gets an umount request from the kernel.
srv.Serve()
// main exits with code 0
}
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// pathfsFrontend - initialize gocryptfs/pathfs_frontend
// Calls os.Exit on errors
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func pathfsFrontend(key []byte, args argContainer, confFile *cryptfs.ConfFile) *fuse.Server {
// Reconciliate CLI and config file arguments into a Args struct that is passed to the
// filesystem implementation
frontendArgs := pathfs_frontend.Args{
Cipherdir: args.cipherdir,
Masterkey: key,
OpenSSL: args.openssl,
PlaintextNames: args.plaintextnames,
DirIV: args.diriv,
}
// 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(cryptfs.FlagPlaintextNames)
frontendArgs.DirIV = confFile.IsFeatureFlagSet(cryptfs.FlagDirIV)
}
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finalFs := pathfs_frontend.NewFS(frontendArgs)
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
// Set values shown in "df -T" and friends
// First column, "Filesystem"
mOpts.Options = append(mOpts.Options, "fsname="+args.cipherdir)
// Second column, "Type", will be shown as "fuse." + Name
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mOpts.Name = "gocryptfs"
srv, err := fuse.NewServer(conn.RawFS(), args.mountpoint, &mOpts)
if err != nil {
fmt.Printf("Mount failed: %v", err)
os.Exit(ERREXIT_MOUNT)
}
srv.SetDebug(args.fusedebug)
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 {
fmt.Print(err)
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cryptfs.Info.Printf("Trying lazy unmount\n")
cmd := exec.Command("fusermount", "-u", "-z", mountpoint)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Run()
}
os.Exit(1)
}()
}