Re-design of the original gocryptfs code to work as a library.
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 

537 lines
19 KiB

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"
"golang.org/x/crypto/chacha20poly1305"
"github.com/hanwen/go-fuse/v2/fs"
"github.com/hanwen/go-fuse/v2/fuse"
"github.com/rfjakob/gocryptfs/v2/internal/configfile"
"github.com/rfjakob/gocryptfs/v2/internal/contentenc"
"github.com/rfjakob/gocryptfs/v2/internal/cryptocore"
"github.com/rfjakob/gocryptfs/v2/internal/ctlsocksrv"
"github.com/rfjakob/gocryptfs/v2/internal/exitcodes"
"github.com/rfjakob/gocryptfs/v2/internal/fusefrontend"
"github.com/rfjakob/gocryptfs/v2/internal/fusefrontend_reverse"
"github.com/rfjakob/gocryptfs/v2/internal/nametransform"
"github.com/rfjakob/gocryptfs/v2/internal/openfiletable"
"github.com/rfjakob/gocryptfs/v2/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
IVBits := contentenc.DefaultIVBits
if args.openssl {
cryptoBackend = cryptocore.BackendOpenSSL
}
if args.aessiv {
cryptoBackend = cryptocore.BackendAESSIV
}
if args.xchacha {
if args.openssl {
cryptoBackend = cryptocore.BackendXChaCha20Poly1305OpenSSL
} else {
cryptoBackend = cryptocore.BackendXChaCha20Poly1305
}
IVBits = chacha20poly1305.NonceSizeX * 8
}
// 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,
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,
OneFileSystem: args.one_file_system,
DeterministicNames: args.deterministic_names,
}
// 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.DeterministicNames = !confFile.IsFeatureFlagSet(configfile.FlagDirIV)
args.raw64 = confFile.IsFeatureFlagSet(configfile.FlagRaw64)
args.hkdf = confFile.IsFeatureFlagSet(configfile.FlagHKDF)
// Note: this will always return the non-openssl variant
cryptoBackend, err = confFile.ContentEncryption()
if err != nil {
tlog.Fatal.Printf("%v", err)
os.Exit(exitcodes.DeprecatedFS)
}
IVBits = cryptoBackend.NonceSize * 8
if cryptoBackend != cryptocore.BackendAESSIV && args.reverse {
tlog.Fatal.Printf("AES-SIV is required by reverse mode, but not enabled in the config file")
os.Exit(exitcodes.Usage)
}
// Upgrade to OpenSSL variant if requested
if args.openssl {
switch cryptoBackend {
case cryptocore.BackendGoGCM:
cryptoBackend = cryptocore.BackendOpenSSL
case cryptocore.BackendXChaCha20Poly1305:
cryptoBackend = cryptocore.BackendXChaCha20Poly1305OpenSSL
}
}
}
// 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, IVBits, args.hkdf, args.forcedecode)
cEnc := contentenc.New(cCore, contentenc.DefaultBS, args.forcedecode)
nameTransform := nametransform.New(cCore.EMECipher, frontendArgs.LongNames,
args.raw64, []string(args.badname), frontendArgs.DeterministicNames)
// 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,
// The kernel usually submits multiple read requests in parallel,
// which means we serve them in any order. Out-of-order reads are
// expensive on some backing network filesystems
// ( https://github.com/rfjakob/gocryptfs/issues/92 ).
//
// Setting SyncRead disables FUSE_CAP_ASYNC_READ. This makes the kernel
// do everything in-order without parallelism.
SyncRead: args.serialize_reads,
}
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()
return strings.HasPrefix(v, "fusermount version")
}
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()
}
}
}