libgocryptfs/pathfs_frontend/fs.go

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package pathfs_frontend
import (
"encoding/base64"
"fmt"
"os"
"path/filepath"
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"sync"
"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/cryptfs"
)
type FS struct {
*cryptfs.CryptFS
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pathfs.FileSystem // loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
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args Args // Stores configuration arguments
// dirIVLock: Lock()ed if any "gocryptfs.diriv" file is modified
// Readers must RLock() it to prevent them from seeing intermediate
// states
dirIVLock sync.RWMutex
}
// Encrypted FUSE overlay filesystem
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func NewFS(args Args) *FS {
return &FS{
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CryptFS: cryptfs.NewCryptFS(args.Masterkey, args.OpenSSL, args.PlaintextNames),
FileSystem: pathfs.NewLoopbackFileSystem(args.Cipherdir),
args: args,
}
}
// GetBackingPath - get the absolute encrypted path of the backing file
// from the relative plaintext path "relPath"
func (fs *FS) getBackingPath(relPath string) (string, error) {
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cPath, err := fs.encryptPath(relPath)
if err != nil {
return "", err
}
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cAbsPath := filepath.Join(fs.args.Cipherdir, cPath)
cryptfs.Debug.Printf("getBackingPath: %s + %s -> %s\n", fs.args.Cipherdir, relPath, cAbsPath)
return cAbsPath, nil
}
func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
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cryptfs.Debug.Printf("FS.GetAttr('%s')\n", name)
if fs.CryptFS.IsFiltered(name) {
return nil, fuse.EPERM
}
cName, err := fs.encryptPath(name)
if err != nil {
return nil, fuse.ToStatus(err)
}
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a, status := fs.FileSystem.GetAttr(cName, context)
if a == nil {
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cryptfs.Debug.Printf("FS.GetAttr failed: %s\n", status.String())
return a, status
}
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if a.IsRegular() {
a.Size = fs.CipherSizeToPlainSize(a.Size)
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} else if a.IsSymlink() {
target, _ := fs.Readlink(name, context)
a.Size = uint64(len(target))
}
return a, status
}
func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, fuse.Status) {
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cryptfs.Debug.Printf("OpenDir(%s)\n", dirName)
cDirName, err := fs.encryptPath(dirName)
if err != nil {
return nil, fuse.ToStatus(err)
}
cipherEntries, status := fs.FileSystem.OpenDir(cDirName, context)
var plain []fuse.DirEntry
if cipherEntries != nil {
for i := range cipherEntries {
cName := cipherEntries[i].Name
if dirName == "" && cName == cryptfs.ConfDefaultName {
// silently ignore "gocryptfs.conf" in the top level dir
continue
}
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if fs.args.DirIV && cName == cryptfs.DIRIV_FILENAME {
// silently ignore "gocryptfs.diriv" everywhere if dirIV is enabled
continue
}
var name string
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if !fs.args.DirIV {
name, err = fs.decryptPath(cName)
} else {
// When dirIV is enabled we need the full path to be able to decrypt it
cPath := filepath.Join(cDirName, cName)
name, err = fs.decryptPath(cPath)
name = filepath.Base(name)
}
if err != nil {
cryptfs.Warn.Printf("Invalid name \"%s\" in dir \"%s\": %s\n", cName, dirName, err)
continue
}
cipherEntries[i].Name = name
plain = append(plain, cipherEntries[i])
}
}
return plain, status
}
// We always need read access to do read-modify-write cycles
func (fs *FS) mangleOpenFlags(flags uint32) (newFlags int, writeOnly bool) {
newFlags = int(flags)
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if newFlags&os.O_WRONLY > 0 {
writeOnly = true
newFlags = newFlags ^ os.O_WRONLY | os.O_RDWR
}
// We also cannot open the file in append mode, we need to seek back for RMW
newFlags = newFlags &^ os.O_APPEND
return newFlags, writeOnly
}
func (fs *FS) Open(path string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
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if fs.CryptFS.IsFiltered(path) {
return nil, fuse.EPERM
}
iflags, writeOnly := fs.mangleOpenFlags(flags)
cPath, err := fs.getBackingPath(path)
if err != nil {
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cryptfs.Debug.Printf("Open: getBackingPath: %v\n", err)
return nil, fuse.ToStatus(err)
}
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cryptfs.Debug.Printf("Open: %s\n", cPath)
f, err := os.OpenFile(cPath, iflags, 0666)
if err != nil {
return nil, fuse.ToStatus(err)
}
return NewFile(f, writeOnly, fs.CryptFS), fuse.OK
}
func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Context) (fuseFile nodefs.File, code fuse.Status) {
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if fs.CryptFS.IsFiltered(path) {
return nil, fuse.EPERM
}
iflags, writeOnly := fs.mangleOpenFlags(flags)
cPath, err := fs.getBackingPath(path)
if err != nil {
return nil, fuse.ToStatus(err)
}
f, err := os.OpenFile(cPath, iflags|os.O_CREATE, os.FileMode(mode))
if err != nil {
return nil, fuse.ToStatus(err)
}
return NewFile(f, writeOnly, fs.CryptFS), fuse.OK
}
func (fs *FS) Chmod(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
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if fs.CryptFS.IsFiltered(path) {
return fuse.EPERM
}
cPath, err := fs.encryptPath(path)
if err != nil {
return fuse.ToStatus(err)
}
return fs.FileSystem.Chmod(cPath, mode, context)
}
func (fs *FS) Chown(path string, uid uint32, gid uint32, context *fuse.Context) (code fuse.Status) {
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if fs.CryptFS.IsFiltered(path) {
return fuse.EPERM
}
cPath, err := fs.encryptPath(path)
if err != nil {
return fuse.ToStatus(err)
}
return fs.FileSystem.Chown(cPath, uid, gid, context)
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}
func (fs *FS) Mknod(path string, mode uint32, dev uint32, context *fuse.Context) (code fuse.Status) {
if fs.CryptFS.IsFiltered(path) {
return fuse.EPERM
}
cPath, err := fs.encryptPath(path)
if err != nil {
return fuse.ToStatus(err)
}
return fs.FileSystem.Mknod(cPath, mode, dev, context)
}
func (fs *FS) Truncate(path string, offset uint64, context *fuse.Context) (code fuse.Status) {
cryptfs.Warn.Printf("Truncate of a closed file is not supported, returning ENOSYS\n")
return fuse.ENOSYS
}
func (fs *FS) Utimens(path string, Atime *time.Time, Mtime *time.Time, context *fuse.Context) (code fuse.Status) {
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if fs.CryptFS.IsFiltered(path) {
return fuse.EPERM
}
cPath, err := fs.encryptPath(path)
if err != nil {
return fuse.ToStatus(err)
}
return fs.FileSystem.Utimens(cPath, Atime, Mtime, context)
}
func (fs *FS) Readlink(path string, context *fuse.Context) (out string, status fuse.Status) {
cPath, err := fs.encryptPath(path)
if err != nil {
return "", fuse.ToStatus(err)
}
cTarget, status := fs.FileSystem.Readlink(cPath, context)
if status != fuse.OK {
return "", status
}
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// Old filesystem: symlinks are encrypted like paths (CBC)
if !fs.args.DirIV {
target, err := fs.decryptPath(cTarget)
if err != nil {
cryptfs.Warn.Printf("Readlink: CBC decryption failed: %v", err)
return "", fuse.EIO
}
return target, fuse.OK
}
// Since gocryptfs v0.5 symlinks are encrypted like file contents (GCM)
cBinTarget, err := base64.URLEncoding.DecodeString(cTarget)
if err != nil {
cryptfs.Warn.Printf("Readlink: %v\n", err)
return "", fuse.EIO
}
target, err := fs.CryptFS.DecryptBlock([]byte(cBinTarget), 0, nil)
if err != nil {
cryptfs.Warn.Printf("Readlink: %v\n", err)
return "", fuse.EIO
}
return string(target), fuse.OK
}
func (fs *FS) Mkdir(relPath string, mode uint32, context *fuse.Context) (code fuse.Status) {
if fs.CryptFS.IsFiltered(relPath) {
return fuse.EPERM
}
encPath, err := fs.getBackingPath(relPath)
if err != nil {
return fuse.ToStatus(err)
}
// Create directory
fs.dirIVLock.Lock()
defer fs.dirIVLock.Unlock()
err = os.Mkdir(encPath, os.FileMode(mode))
if err != nil {
return fuse.ToStatus(err)
}
// Create gocryptfs.diriv inside
err = cryptfs.WriteDirIV(encPath)
if err != nil {
// This should not happen
cryptfs.Warn.Printf("Creating %s in dir %s failed: %v\n", cryptfs.DIRIV_FILENAME, encPath, err)
err2 := syscall.Rmdir(encPath)
if err2 != nil {
cryptfs.Warn.Printf("Mkdir: Rollback failed: %v\n", err2)
}
return fuse.ToStatus(err)
}
return fuse.OK
}
func (fs *FS) Unlink(path string, context *fuse.Context) (code fuse.Status) {
if fs.CryptFS.IsFiltered(path) {
return fuse.EPERM
}
cPath, err := fs.getBackingPath(path)
if err != nil {
return fuse.ToStatus(err)
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}
return fuse.ToStatus(syscall.Unlink(cPath))
}
func (fs *FS) Rmdir(name string, context *fuse.Context) (code fuse.Status) {
encPath, err := fs.getBackingPath(name)
if err != nil {
return fuse.ToStatus(err)
}
// If the directory is not empty besides gocryptfs.diriv, do not even
// attempt the dance around gocryptfs.diriv.
fd, err := os.Open(encPath)
if err != nil {
return fuse.ToStatus(err)
}
defer fd.Close()
list, err := fd.Readdirnames(10)
if err != nil {
return fuse.ToStatus(err)
}
if len(list) > 1 {
return fuse.ToStatus(syscall.ENOTEMPTY)
}
// Move "gocryptfs.diriv" to the parent dir under name "gocryptfs.diriv.rmdir.INODENUMBER"
var st syscall.Stat_t
err = syscall.Fstat(int(fd.Fd()), &st)
if err != nil {
return fuse.ToStatus(err)
}
dirivPath := filepath.Join(encPath, cryptfs.DIRIV_FILENAME)
parentDir := filepath.Dir(encPath)
tmpName := fmt.Sprintf("gocryptfs.diriv.rmdir.%d", st.Ino)
tmpDirivPath := filepath.Join(parentDir, tmpName)
cryptfs.Debug.Printf("Rmdir: Renaming %s to %s\n", cryptfs.DIRIV_FILENAME, tmpDirivPath)
fs.dirIVLock.Lock() // directory will be in an inconsistent state after the rename
defer fs.dirIVLock.Unlock()
err = os.Rename(dirivPath, tmpDirivPath)
if err != nil {
cryptfs.Warn.Printf("Rmdir: Renaming %s to %s failed: %v\n", cryptfs.DIRIV_FILENAME, tmpDirivPath, err)
return fuse.ToStatus(err)
}
// Actual Rmdir
err = syscall.Rmdir(encPath)
if err != nil {
// This can happen if another file in the directory was created in the
// meantime, undo the rename
err2 := os.Rename(tmpDirivPath, dirivPath)
if err2 != nil {
cryptfs.Warn.Printf("Rmdir: Rollback failed: %v\n", err2)
}
return fuse.ToStatus(err)
}
// Delete "gocryptfs.diriv.rmdir.INODENUMBER"
err = syscall.Unlink(tmpDirivPath)
if err != nil {
cryptfs.Warn.Printf("Rmdir: Could not clean up %s: %v\n", tmpName, err)
}
return fuse.OK
}
func (fs *FS) Symlink(target string, linkName string, context *fuse.Context) (code fuse.Status) {
cryptfs.Debug.Printf("Symlink(\"%s\", \"%s\")\n", target, linkName)
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if fs.CryptFS.IsFiltered(linkName) {
return fuse.EPERM
}
cPath, err := fs.getBackingPath(linkName)
if err != nil {
return fuse.ToStatus(err)
}
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// Old filesystem: symlinks are encrypted like paths (CBC)
if !fs.args.DirIV {
cTarget, err := fs.encryptPath(target)
if err != nil {
cryptfs.Warn.Printf("Symlink: BUG: we should not get an error here: %v\n", err)
return fuse.ToStatus(err)
}
err = os.Symlink(cTarget, cPath)
return fuse.ToStatus(err)
}
// Since gocryptfs v0.5 symlinks are encrypted like file contents (GCM)
cBinTarget := fs.CryptFS.EncryptBlock([]byte(target), 0, nil)
cTarget := base64.URLEncoding.EncodeToString(cBinTarget)
err = os.Symlink(cTarget, cPath)
cryptfs.Debug.Printf("Symlink: os.Symlink(%s, %s) = %v\n", cTarget, cPath, err)
return fuse.ToStatus(err)
}
func (fs *FS) Rename(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) {
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if fs.CryptFS.IsFiltered(newPath) {
return fuse.EPERM
}
cOldPath, err := fs.getBackingPath(oldPath)
if err != nil {
return fuse.ToStatus(err)
}
cNewPath, err := fs.getBackingPath(newPath)
if err != nil {
return fuse.ToStatus(err)
}
return fs.FileSystem.Rename(cOldPath, cNewPath, context)
}
func (fs *FS) Link(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) {
if fs.CryptFS.IsFiltered(newPath) {
return fuse.EPERM
}
cOldPath, err := fs.getBackingPath(oldPath)
if err != nil {
return fuse.ToStatus(err)
}
cNewPath, err := fs.getBackingPath(newPath)
if err != nil {
return fuse.ToStatus(err)
}
return fuse.ToStatus(os.Link(cOldPath, cNewPath))
}
func (fs *FS) Access(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
if fs.CryptFS.IsFiltered(path) {
return fuse.EPERM
}
cPath, err := fs.getBackingPath(path)
if err != nil {
return fuse.ToStatus(err)
}
return fuse.ToStatus(syscall.Access(cPath, mode))
}
func (fs *FS) GetXAttr(name string, attr string, context *fuse.Context) ([]byte, fuse.Status) {
return nil, fuse.ENOSYS
}
func (fs *FS) SetXAttr(name string, attr string, data []byte, flags int, context *fuse.Context) fuse.Status {
return fuse.ENOSYS
}
func (fs *FS) ListXAttr(name string, context *fuse.Context) ([]string, fuse.Status) {
return nil, fuse.ENOSYS
}
func (fs *FS) RemoveXAttr(name string, attr string, context *fuse.Context) fuse.Status {
return fuse.ENOSYS
}