libgocryptfs/main.go

474 lines
16 KiB
Go

package main
import (
"encoding/json"
"flag"
"fmt"
"log/syslog"
"os"
"os/exec"
"os/signal"
"path/filepath"
"runtime"
"runtime/pprof"
"strconv"
"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/contentenc"
"github.com/rfjakob/gocryptfs/internal/cryptocore"
"github.com/rfjakob/gocryptfs/internal/fusefrontend"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/prefer_openssl"
"github.com/rfjakob/gocryptfs/internal/readpassword"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
const (
// Exit codes
ERREXIT_USAGE = 1
ERREXIT_MOUNT = 3
ERREXIT_CIPHERDIR = 6
ERREXIT_INIT = 7
ERREXIT_LOADCONF = 8
ERREXIT_MOUNTPOINT = 10
)
type argContainer struct {
debug, init, zerokey, fusedebug, openssl, passwd, foreground, version,
plaintextnames, quiet, nosyslog, wpanic,
longnames, allow_other, ro bool
masterkey, mountpoint, cipherdir, cpuprofile, config, extpass,
memprofile, o string
notifypid, scryptn int
}
var flagSet *flag.FlagSet
const pleaseBuildBash = "[not set - please compile using ./build.bash]"
// gocryptfs version according to git, set by build.bash
var GitVersion = pleaseBuildBash
// go-fuse library version, set by build.bash
var GitVersionFuse = pleaseBuildBash
// Unix timestamp, set by build.bash
var BuildTime = "0"
// initDir initializes an empty directory for use as a gocryptfs cipherdir.
func initDir(args *argContainer) {
err := checkDirEmpty(args.cipherdir)
if err != nil {
tlog.Fatal.Printf("Invalid cipherdir: %v", err)
os.Exit(ERREXIT_INIT)
}
// Create gocryptfs.conf
if args.extpass == "" {
tlog.Info.Printf("Choose a password for protecting your files.")
} else {
tlog.Info.Printf("Using password provided via -extpass.")
}
password := readpassword.Twice(args.extpass)
creator := tlog.ProgramName + " " + GitVersion
err = configfile.CreateConfFile(args.config, password, args.plaintextnames, args.scryptn, creator)
if err != nil {
tlog.Fatal.Println(err)
os.Exit(ERREXIT_INIT)
}
if !args.plaintextnames {
// Create gocryptfs.diriv in the root dir
err = nametransform.WriteDirIV(args.cipherdir)
if err != nil {
tlog.Fatal.Println(err)
os.Exit(ERREXIT_INIT)
}
}
tlog.Info.Printf(tlog.ColorGreen + "The filesystem has been created successfully." + tlog.ColorReset)
wd, _ := os.Getwd()
friendlyPath, _ := filepath.Rel(wd, args.cipherdir)
if strings.HasPrefix(friendlyPath, "../") {
// A relative path that starts with "../" is pretty unfriendly, just
// keep the absolute path.
friendlyPath = args.cipherdir
}
tlog.Info.Printf(tlog.ColorGrey+"You can now mount it using: %s %s MOUNTPOINT"+tlog.ColorReset,
tlog.ProgramName, friendlyPath)
os.Exit(0)
}
func usageText() {
printVersion()
fmt.Printf(`
Usage: %s -init|-passwd [OPTIONS] CIPHERDIR
or %s [OPTIONS] CIPHERDIR MOUNTPOINT
Options:
`, tlog.ProgramName, tlog.ProgramName)
flagSet.PrintDefaults()
}
// loadConfig - load the config file "filename", prompting the user for the password
func loadConfig(args *argContainer) (masterkey []byte, confFile *configfile.ConfFile) {
// Check if the file exists at all before prompting for a password
_, err := os.Stat(args.config)
if err != nil {
tlog.Fatal.Printf("Config file not found: %v", err)
os.Exit(ERREXIT_LOADCONF)
}
pw := readpassword.Once(args.extpass)
tlog.Info.Println("Decrypting master key")
masterkey, confFile, err = configfile.LoadConfFile(args.config, pw)
if err != nil {
tlog.Fatal.Println(err)
os.Exit(ERREXIT_LOADCONF)
}
return masterkey, confFile
}
// changePassword - change the password of config file "filename"
func changePassword(args *argContainer) {
masterkey, confFile := loadConfig(args)
tlog.Info.Println("Please enter your new password.")
newPw := readpassword.Twice(args.extpass)
confFile.EncryptKey(masterkey, newPw, confFile.ScryptObject.LogN())
err := confFile.WriteFile()
if err != nil {
tlog.Fatal.Println(err)
os.Exit(ERREXIT_INIT)
}
tlog.Info.Printf("Password changed.")
os.Exit(0)
}
// printVersion prints a version string like this:
// gocryptfs v0.12-36-ge021b9d-dirty; go-fuse a4c968c; 2016-07-03 go1.6.2
func printVersion() {
humanTime := "0000-00-00"
if i, _ := strconv.ParseInt(BuildTime, 10, 64); i > 0 {
t := time.Unix(i, 0).UTC()
humanTime = fmt.Sprintf("%d-%02d-%02d", t.Year(), t.Month(), t.Day())
}
built := fmt.Sprintf("%s %s", humanTime, runtime.Version())
fmt.Printf("%s %s; go-fuse %s; %s\n",
tlog.ProgramName, GitVersion, GitVersionFuse, built)
}
func main() {
runtime.GOMAXPROCS(4)
var err error
var args argContainer
// Parse command line arguments
var opensslAuto string
flagSet = flag.NewFlagSet(tlog.ProgramName, flag.ExitOnError)
flagSet.Usage = usageText
flagSet.BoolVar(&args.debug, "d", false, "")
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")
// Tri-state true/false/auto
flagSet.StringVar(&opensslAuto, "openssl", "auto", "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")
flagSet.BoolVar(&args.plaintextnames, "plaintextnames", false, "Do not encrypt file names")
flagSet.BoolVar(&args.quiet, "q", false, "")
flagSet.BoolVar(&args.quiet, "quiet", false, "Quiet - silence informational messages")
flagSet.BoolVar(&args.nosyslog, "nosyslog", false, "Do not redirect output to syslog when running in the background")
flagSet.BoolVar(&args.wpanic, "wpanic", false, "When encountering a warning, panic and exit immediately")
flagSet.BoolVar(&args.longnames, "longnames", true, "Store names longer than 176 bytes in extra files")
flagSet.BoolVar(&args.allow_other, "allow_other", false, "Allow other users to access the filesystem. "+
"Only works if user_allow_other is set in /etc/fuse.conf.")
flagSet.BoolVar(&args.ro, "ro", false, "Mount the filesystem read-only")
flagSet.StringVar(&args.masterkey, "masterkey", "", "Mount with explicit master key")
flagSet.StringVar(&args.cpuprofile, "cpuprofile", "", "Write cpu profile to specified file")
flagSet.StringVar(&args.memprofile, "memprofile", "", "Write memory 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")
flagSet.StringVar(&args.o, "o", "", "Pass additional mount options to the kernel, comma-separated list")
flagSet.IntVar(&args.notifypid, "notifypid", 0, "Send USR1 to the specified process after "+
"successful mount - used internally for daemonization")
flagSet.IntVar(&args.scryptn, "scryptn", configfile.ScryptDefaultLogN, "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:])
// "-openssl" needs some post-processing
if opensslAuto == "auto" {
args.openssl = prefer_openssl.PreferOpenSSL()
} else {
args.openssl, err = strconv.ParseBool(opensslAuto)
if err != nil {
tlog.Fatal.Printf("Invalid \"-openssl\" setting: %v", err)
os.Exit(ERREXIT_USAGE)
}
}
// 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
}
if args.debug {
tlog.Debug.Enabled = true
}
// "-v"
if args.version {
tlog.Debug.Printf("openssl=%v\n", args.openssl)
tlog.Debug.Printf("on-disk format %d\n", contentenc.CurrentVersion)
printVersion()
os.Exit(0)
}
if args.wpanic {
tlog.Warn.Wpanic = true
tlog.Debug.Printf("Panicing on warnings")
}
// 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 {
tlog.Fatal.Printf("Invalid cipherdir: %v", err)
os.Exit(ERREXIT_CIPHERDIR)
}
} else {
usageText()
os.Exit(ERREXIT_USAGE)
}
// "-q"
if args.quiet {
tlog.Info.Enabled = false
}
// "-config"
if args.config != "" {
args.config, err = filepath.Abs(args.config)
if err != nil {
tlog.Fatal.Printf("Invalid \"-config\" setting: %v", err)
os.Exit(ERREXIT_INIT)
}
tlog.Info.Printf("Using config file at custom location %s", args.config)
} else {
args.config = filepath.Join(args.cipherdir, configfile.ConfDefaultName)
}
// "-cpuprofile"
if args.cpuprofile != "" {
tlog.Info.Printf("Writing CPU profile to %s", args.cpuprofile)
var f *os.File
f, err = os.Create(args.cpuprofile)
if err != nil {
tlog.Fatal.Println(err)
os.Exit(ERREXIT_INIT)
}
pprof.StartCPUProfile(f)
defer pprof.StopCPUProfile()
}
// "-memprofile"
if args.memprofile != "" {
tlog.Info.Printf("Writing mem profile to %s", args.memprofile)
var f *os.File
f, err = os.Create(args.memprofile)
if err != nil {
tlog.Fatal.Println(err)
os.Exit(ERREXIT_INIT)
}
defer func() {
pprof.WriteHeapProfile(f)
f.Close()
return
}()
}
if args.cpuprofile != "" || args.memprofile != "" {
tlog.Info.Printf("Note: You must unmount gracefully, otherwise the profile file(s) will stay empty!\n")
}
// "-openssl"
if args.openssl == false {
tlog.Debug.Printf("OpenSSL disabled, using Go GCM")
} else {
tlog.Debug.Printf("OpenSSL enabled")
}
// Operation flags: init, passwd or mount
// "-init"
if args.init {
if flagSet.NArg() > 1 {
tlog.Fatal.Printf("Usage: %s -init [OPTIONS] CIPHERDIR", tlog.ProgramName)
os.Exit(ERREXIT_USAGE)
}
initDir(&args) // does not return
}
// "-passwd"
if args.passwd {
if flagSet.NArg() > 1 {
tlog.Fatal.Printf("Usage: %s -passwd [OPTIONS] CIPHERDIR", tlog.ProgramName)
os.Exit(ERREXIT_USAGE)
}
changePassword(&args) // does not return
}
// Mount
// Check mountpoint
if flagSet.NArg() != 2 {
tlog.Fatal.Printf("Usage: %s [OPTIONS] CIPHERDIR MOUNTPOINT", tlog.ProgramName)
os.Exit(ERREXIT_USAGE)
}
args.mountpoint, err = filepath.Abs(flagSet.Arg(1))
if err != nil {
tlog.Fatal.Printf("Invalid mountpoint: %v", err)
os.Exit(ERREXIT_MOUNTPOINT)
}
err = checkDirEmpty(args.mountpoint)
if err != nil {
tlog.Fatal.Printf("Invalid mountpoint: %v", err)
os.Exit(ERREXIT_MOUNTPOINT)
}
// Get master key
var masterkey []byte
var confFile *configfile.ConfFile
if args.masterkey != "" {
// "-masterkey"
tlog.Info.Printf("Using explicit master key.")
masterkey = parseMasterKey(args.masterkey)
tlog.Info.Printf(tlog.ColorYellow +
"THE MASTER KEY IS VISIBLE VIA \"ps ax\" AND MAY BE STORED IN YOUR SHELL HISTORY!\n" +
"ONLY USE THIS MODE FOR EMERGENCIES." + tlog.ColorReset)
} 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
masterkey, confFile = loadConfig(&args)
printMasterKey(masterkey)
}
// Initialize FUSE server
tlog.Debug.Printf("cli args: %v", args)
srv := initFuseFrontend(masterkey, args, confFile)
tlog.Info.Println(tlog.ColorGreen + "Filesystem mounted and ready." + tlog.ColorReset)
// We are ready - send USR1 signal to our parent and switch to syslog
if args.notifypid > 0 {
sendUsr1(args.notifypid)
if !args.nosyslog {
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)
}
}
// 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
}
// 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 Args struct that is passed to the
// filesystem implementation
frontendArgs := fusefrontend.Args{
Cipherdir: args.cipherdir,
Masterkey: key,
OpenSSL: args.openssl,
PlaintextNames: args.plaintextnames,
LongNames: args.longnames,
}
// 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)
}
// 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))
finalFs := fusefrontend.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
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")
}
// 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
mOpts.Name = "gocryptfs"
// The kernel enforces read-only operation, we just have to pass "ro".
if args.ro {
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.o != "" {
parts := strings.Split(args.o, ",")
tlog.Debug.Printf("Adding -o 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(ERREXIT_MOUNT)
}
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)
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)
}()
}