Re-design of the original gocryptfs code to work as a library.
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libgocryptfs/internal/fusefrontend/fs_dir.go

367 lines
11 KiB

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
}