libgocryptfs/internal/fusefrontend/fs_dir.go
Jakob Unterwurzacher 70bcf58a9b syscallcompat: convert Getdents to fd input, add emulation
Now that we have Fstatat we can use it in Getdents to
get rid of the path name.

Also, add an emulated version of getdents for MacOS. This allows
to drop the !HaveGetdents special cases from fusefrontend.

Modify the getdents test to test both native getdents and the emulated
version.
2017-12-03 19:33:26 +01:00

368 lines
11 KiB
Go

package fusefrontend
// Mkdir and Rmdir
import (
"fmt"
"io"
"os"
"path/filepath"
"runtime"
"sync"
"syscall"
"golang.org/x/sys/unix"
"github.com/hanwen/go-fuse/fuse"
"github.com/rfjakob/gocryptfs/internal/configfile"
"github.com/rfjakob/gocryptfs/internal/cryptocore"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
const dsStoreName = ".DS_Store"
// mkdirWithIv - create a new directory and corresponding diriv file. dirfd
// should be a handle to the parent directory, cName is the name of the new
// directory and mode specifies the access permissions to use.
func (fs *FS) mkdirWithIv(dirfd *os.File, cName string, mode uint32) error {
// Between the creation of the directory and the creation of gocryptfs.diriv
// the directory is inconsistent. Take the lock to prevent other readers
// from seeing it.
fs.dirIVLock.Lock()
// The new directory may take the place of an older one that is still in the cache
fs.nameTransform.DirIVCache.Clear()
defer fs.dirIVLock.Unlock()
err := syscallcompat.Mkdirat(int(dirfd.Fd()), cName, mode)
if err != nil {
return err
}
// Create gocryptfs.diriv
err = nametransform.WriteDirIV(dirfd, cName)
if err != nil {
err2 := syscallcompat.Unlinkat(int(dirfd.Fd()), cName, unix.AT_REMOVEDIR)
if err2 != nil {
tlog.Warn.Printf("mkdirWithIv: rollback failed: %v", err2)
}
}
return err
}
// Mkdir implements pathfs.FileSystem
func (fs *FS) Mkdir(newPath string, mode uint32, context *fuse.Context) (code fuse.Status) {
if fs.isFiltered(newPath) {
return fuse.EPERM
}
dirfd, cName, err := fs.openBackingPath(newPath)
if err != nil {
return fuse.ToStatus(err)
}
defer dirfd.Close()
if fs.args.PlaintextNames {
err = syscallcompat.Mkdirat(int(dirfd.Fd()), cName, mode)
// Set owner
if fs.args.PreserveOwner {
err = syscallcompat.Fchownat(int(dirfd.Fd()), cName, int(context.Owner.Uid),
int(context.Owner.Gid), unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
tlog.Warn.Printf("Mkdir: Fchownat failed: %v", err)
}
}
return fuse.ToStatus(err)
}
// We need write and execute permissions to create gocryptfs.diriv
origMode := mode
mode = mode | 0300
// Handle long file name
if nametransform.IsLongContent(cName) {
// Create ".name"
err = fs.nameTransform.WriteLongName(dirfd, cName, newPath)
if err != nil {
return fuse.ToStatus(err)
}
// Create directory
err = fs.mkdirWithIv(dirfd, cName, mode)
if err != nil {
nametransform.DeleteLongName(dirfd, cName)
return fuse.ToStatus(err)
}
} else {
err = fs.mkdirWithIv(dirfd, cName, mode)
if err != nil {
return fuse.ToStatus(err)
}
}
// Set permissions back to what the user wanted
if origMode != mode {
err = syscallcompat.Fchmodat(int(dirfd.Fd()), cName, origMode, unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
tlog.Warn.Printf("Mkdir: Fchmodat failed: %v", err)
}
}
// Set owner
if fs.args.PreserveOwner {
err = syscallcompat.Fchownat(int(dirfd.Fd()), cName, int(context.Owner.Uid),
int(context.Owner.Gid), unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
tlog.Warn.Printf("Mkdir: Fchownat 1 failed: %v", err)
}
err = syscallcompat.Fchownat(int(dirfd.Fd()), filepath.Join(cName, nametransform.DirIVFilename),
int(context.Owner.Uid), int(context.Owner.Gid), unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
tlog.Warn.Printf("Mkdir: Fchownat 2 failed: %v", err)
}
}
return fuse.OK
}
// haveDsstore return true if one of the entries in "names" is ".DS_Store".
func haveDsstore(names []string) bool {
for _, n := range names {
if n == dsStoreName {
return true
}
}
return false
}
// Rmdir implements pathfs.FileSystem
func (fs *FS) Rmdir(path string, context *fuse.Context) (code fuse.Status) {
cPath, err := fs.getBackingPath(path)
if err != nil {
return fuse.ToStatus(err)
}
if fs.args.PlaintextNames {
err = syscall.Rmdir(cPath)
return fuse.ToStatus(err)
}
parentDir := filepath.Dir(cPath)
parentDirFd, err := os.Open(parentDir)
if err != nil {
return fuse.ToStatus(err)
}
defer parentDirFd.Close()
cName := filepath.Base(cPath)
dirfdRaw, err := syscallcompat.Openat(int(parentDirFd.Fd()), cName,
syscall.O_RDONLY|syscall.O_NOFOLLOW, 0)
if err == syscall.EACCES {
// We need permission to read and modify the directory
tlog.Debug.Printf("Rmdir: handling EACCESS")
// TODO use syscall.Fstatat once it is available in Go
var fi os.FileInfo
fi, err = os.Lstat(cPath)
if err != nil {
tlog.Debug.Printf("Rmdir: Stat: %v", err)
return fuse.ToStatus(err)
}
origMode := fi.Mode()
// TODO use syscall.Chmodat once it is available in Go
err = os.Chmod(cPath, origMode|0700)
if err != nil {
tlog.Debug.Printf("Rmdir: Chmod failed: %v", err)
return fuse.ToStatus(err)
}
// Retry open
var st syscall.Stat_t
syscall.Lstat(cPath, &st)
dirfdRaw, err = syscallcompat.Openat(int(parentDirFd.Fd()), cName,
syscall.O_RDONLY|syscall.O_NOFOLLOW, 0)
// Undo the chmod if removing the directory failed
defer func() {
if code != fuse.OK {
err = os.Chmod(cPath, origMode)
if err != nil {
tlog.Warn.Printf("Rmdir: Chmod rollback failed: %v", err)
}
}
}()
}
if err != nil {
tlog.Debug.Printf("Rmdir: Open: %v", err)
return fuse.ToStatus(err)
}
dirfd := os.NewFile(uintptr(dirfdRaw), cName)
defer dirfd.Close()
retry:
// Check directory contents
children, err := dirfd.Readdirnames(10)
if err == io.EOF {
// The directory is empty
tlog.Warn.Printf("Rmdir: %q: gocryptfs.diriv is missing", cPath)
return fuse.ToStatus(syscall.Rmdir(cPath))
}
if err != nil {
tlog.Warn.Printf("Rmdir: Readdirnames: %v", err)
return fuse.ToStatus(err)
}
// MacOS sprinkles .DS_Store files everywhere. This is hard to avoid for
// users, so handle it transparently here.
if runtime.GOOS == "darwin" && len(children) <= 2 && haveDsstore(children) {
ds := filepath.Join(cPath, dsStoreName)
err = syscall.Unlink(ds)
if err != nil {
tlog.Warn.Printf("Rmdir: failed to delete blocking file %q: %v", ds, err)
return fuse.ToStatus(err)
}
tlog.Warn.Printf("Rmdir: had to delete blocking file %q", ds)
goto retry
}
// If the directory is not empty besides gocryptfs.diriv, do not even
// attempt the dance around gocryptfs.diriv.
if len(children) > 1 {
return fuse.ToStatus(syscall.ENOTEMPTY)
}
// Move "gocryptfs.diriv" to the parent dir as "gocryptfs.diriv.rmdir.XYZ"
tmpName := fmt.Sprintf("gocryptfs.diriv.rmdir.%d", cryptocore.RandUint64())
tlog.Debug.Printf("Rmdir: Renaming %s to %s", nametransform.DirIVFilename, tmpName)
// The directory is in an inconsistent state between rename and rmdir.
// Protect against concurrent readers.
fs.dirIVLock.Lock()
defer fs.dirIVLock.Unlock()
err = syscallcompat.Renameat(int(dirfd.Fd()), nametransform.DirIVFilename,
int(parentDirFd.Fd()), tmpName)
if err != nil {
tlog.Warn.Printf("Rmdir: Renaming %s to %s failed: %v",
nametransform.DirIVFilename, tmpName, err)
return fuse.ToStatus(err)
}
// Actual Rmdir
err = syscallcompat.Unlinkat(int(parentDirFd.Fd()), cName, unix.AT_REMOVEDIR)
if err != nil {
// This can happen if another file in the directory was created in the
// meantime, undo the rename
err2 := syscallcompat.Renameat(int(parentDirFd.Fd()), tmpName,
int(dirfd.Fd()), nametransform.DirIVFilename)
if err != nil {
tlog.Warn.Printf("Rmdir: Rename rollback failed: %v", err2)
}
return fuse.ToStatus(err)
}
// Delete "gocryptfs.diriv.rmdir.XYZ"
err = syscallcompat.Unlinkat(int(parentDirFd.Fd()), tmpName, 0)
if err != nil {
tlog.Warn.Printf("Rmdir: Could not clean up %s: %v", tmpName, err)
}
// Delete .name file
if nametransform.IsLongContent(cName) {
nametransform.DeleteLongName(parentDirFd, cName)
}
// The now-deleted directory may have been in the DirIV cache. Clear it.
fs.nameTransform.DirIVCache.Clear()
return fuse.OK
}
// If syscallcompat.HaveGetdents is false we will warn once about it
var haveGetdentsWarnOnce sync.Once
// OpenDir implements pathfs.FileSystem
func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, fuse.Status) {
tlog.Debug.Printf("OpenDir(%s)", dirName)
cDirName, err := fs.encryptPath(dirName)
if err != nil {
return nil, fuse.ToStatus(err)
}
// Read ciphertext directory
cDirAbsPath := filepath.Join(fs.args.Cipherdir, cDirName)
var cipherEntries []fuse.DirEntry
var status fuse.Status
fd, err := syscall.Open(cDirAbsPath, syscall.O_RDONLY|syscall.O_NOFOLLOW, 0)
if err != nil {
return nil, fuse.ToStatus(err)
}
defer syscall.Close(fd)
cipherEntries, err = syscallcompat.Getdents(fd)
if err != nil {
return nil, fuse.ToStatus(err)
}
// Get DirIV (stays nil if PlaintextNames is used)
var cachedIV []byte
if !fs.args.PlaintextNames {
cachedIV, _ = fs.nameTransform.DirIVCache.Lookup(dirName)
if cachedIV == nil {
// Read the DirIV from disk and store it in the cache
fs.dirIVLock.RLock()
cachedIV, err = nametransform.ReadDirIV(cDirAbsPath)
if err != nil {
fs.dirIVLock.RUnlock()
// This can happen during normal operation when the directory has
// been deleted concurrently. But it can also mean that the
// gocryptfs.diriv is missing due to an error, so log the event
// at "info" level.
tlog.Info.Printf("OpenDir: %v", err)
return nil, fuse.ToStatus(err)
}
fs.nameTransform.DirIVCache.Store(dirName, cachedIV, cDirName)
fs.dirIVLock.RUnlock()
}
}
// Decrypted directory entries
var plain []fuse.DirEntry
var errorCount int
// Filter and decrypt filenames
for i := range cipherEntries {
cName := cipherEntries[i].Name
if dirName == "" && cName == configfile.ConfDefaultName {
// silently ignore "gocryptfs.conf" in the top level dir
continue
}
if fs.args.PlaintextNames {
plain = append(plain, cipherEntries[i])
continue
}
if cName == nametransform.DirIVFilename {
// silently ignore "gocryptfs.diriv" everywhere if dirIV is enabled
continue
}
// Handle long file name
isLong := nametransform.LongNameNone
if fs.args.LongNames {
isLong = nametransform.NameType(cName)
}
if isLong == nametransform.LongNameContent {
cNameLong, err := nametransform.ReadLongName(filepath.Join(cDirAbsPath, cName))
if err != nil {
tlog.Warn.Printf("OpenDir %q: invalid entry %q: Could not read .name: %v",
cDirName, cName, err)
errorCount++
continue
}
cName = cNameLong
} else if isLong == nametransform.LongNameFilename {
// ignore "gocryptfs.longname.*.name"
continue
}
name, err := fs.nameTransform.DecryptName(cName, cachedIV)
if err != nil {
tlog.Warn.Printf("OpenDir %q: invalid entry %q: %v",
cDirName, cName, err)
if runtime.GOOS == "darwin" && cName == dsStoreName {
// MacOS creates lots of these files. Log the warning but don't
// increment errorCount - does not warrant returning EIO.
continue
}
errorCount++
continue
}
// Override the ciphertext name with the plaintext name but reuse the rest
// of the structure
cipherEntries[i].Name = name
plain = append(plain, cipherEntries[i])
}
if errorCount > 0 && len(plain) == 0 {
// Don't let the user stare on an empty directory. Report that things went
// wrong.
tlog.Warn.Printf("OpenDir %q: all %d entries were invalid, returning EIO",
cDirName, errorCount)
status = fuse.EIO
}
return plain, status
}