fusefronted: make EncryptPath symlink-safe
Finally allows us to delete EncryptPathDirIV.
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59f1300591
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2b12bba274
@ -3,21 +3,45 @@ package fusefrontend
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import (
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"fmt"
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"path"
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"path/filepath"
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"strings"
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"syscall"
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"github.com/rfjakob/gocryptfs/internal/ctlsock"
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"github.com/rfjakob/gocryptfs/internal/nametransform"
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"github.com/rfjakob/gocryptfs/internal/syscallcompat"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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var _ ctlsock.Interface = &FS{} // Verify that interface is implemented.
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// EncryptPath implements ctlsock.Backend
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//
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// TODO: this function is NOT symlink-safe.
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// Symlink-safe through openBackingDir().
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func (fs *FS) EncryptPath(plainPath string) (string, error) {
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return fs.encryptPath(plainPath)
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if plainPath == "" {
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// Empty string gets encrypted as empty string
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return plainPath, nil
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}
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if fs.args.PlaintextNames {
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return plainPath, nil
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}
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// Encrypt path level by level using openBackingDir. Pretty inefficient,
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// but does not matter here.
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parts := strings.Split(plainPath, "/")
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wd := ""
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cPath := ""
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for _, part := range parts {
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wd = filepath.Join(wd, part)
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dirfd, cName, err := fs.openBackingDir(wd)
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if err != nil {
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return "", err
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}
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syscall.Close(dirfd)
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cPath = filepath.Join(cPath, cName)
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}
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tlog.Debug.Printf("encryptPath '%s' -> '%s'", plainPath, cPath)
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return cPath, nil
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}
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// DecryptPath implements ctlsock.Backend
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@ -83,24 +83,3 @@ func (fs *FS) openBackingDir(relPath string) (dirfd int, cName string, err error
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}
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return dirfd, cName, nil
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}
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// encryptPath - encrypt relative plaintext path
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//
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// TODO: this function is NOT symlink-safe because EncryptPathDirIV is not
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// symlink-safe.
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func (fs *FS) encryptPath(plainPath string) (string, error) {
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if plainPath != "" { // Empty path gets encrypted all the time without actual file accesses.
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fs.AccessedSinceLastCheck = 1
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} else { // Empty string gets encrypted as empty string
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return plainPath, nil
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}
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if fs.args.PlaintextNames {
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return plainPath, nil
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}
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fs.dirIVLock.RLock()
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cPath, err := fs.nameTransform.EncryptPathDirIV(plainPath, fs.args.Cipherdir)
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tlog.Debug.Printf("encryptPath '%s' -> '%s' (err: %v)", plainPath, cPath, err)
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fs.dirIVLock.RUnlock()
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return cPath, err
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}
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@ -25,26 +25,6 @@ const (
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DirIVFilename = "gocryptfs.diriv"
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)
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// ReadDirIV - read the "gocryptfs.diriv" file from "dir" (absolute ciphertext path)
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// This function is exported because it allows for an efficient readdir implementation.
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// If the directory itself cannot be opened, a syscall error will be returned.
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// Otherwise, a fmt.Errorf() error value is returned with the details.
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//
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// TODO: this function is not symlink-safe and should be deleted once the only
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// remaining user, EncryptPathDirIV(), is gone.
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func ReadDirIV(dir string) (iv []byte, err error) {
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fd, err := os.Open(filepath.Join(dir, DirIVFilename))
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if err != nil {
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// Note: getting errors here is normal because of concurrent deletes.
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// Strip the useless annotation that os.Open has added and return
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// the plain syscall error. The caller will log a nice message.
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err2 := err.(*os.PathError)
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return nil, err2.Err
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}
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defer fd.Close()
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return fdReadDirIV(fd)
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}
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// ReadDirIVAt reads "gocryptfs.diriv" from the directory that is opened as "dirfd".
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// Using the dirfd makes it immune to concurrent renames of the directory.
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func ReadDirIVAt(dirfd int) (iv []byte, err error) {
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@ -132,53 +112,6 @@ func (be *NameTransform) EncryptAndHashName(name string, iv []byte) string {
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return cName
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}
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// EncryptPathDirIV - encrypt relative plaintext path "plainPath" using EME with
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// DirIV. "rootDir" is the backing storage root directory.
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// Components that are longer than 255 bytes are hashed if be.longnames == true.
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//
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// TODO: EncryptPathDirIV is NOT SAFE against symlink races. This function
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// should eventually be deleted.
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func (be *NameTransform) EncryptPathDirIV(plainPath string, rootDir string) (string, error) {
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var err error
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// Empty string means root directory
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if plainPath == "" {
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return plainPath, nil
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}
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// Reject names longer than 255 bytes.
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baseName := filepath.Base(plainPath)
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if len(baseName) > unix.NAME_MAX {
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return "", syscall.ENAMETOOLONG
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}
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// If we have the iv and the encrypted directory name in the cache, we
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// can skip the directory walk. This optimization yields a 10% improvement
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// in the tar extract benchmark.
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parentDir := Dir(plainPath)
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if iv, cParentDir := be.DirIVCache.Lookup(parentDir); iv != nil {
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cBaseName := be.EncryptAndHashName(baseName, iv)
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return filepath.Join(cParentDir, cBaseName), nil
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}
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// We have to walk the directory tree, starting at the root directory.
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// ciphertext working directory (relative path)
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cipherWD := ""
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// plaintext working directory (relative path)
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plainWD := ""
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plainNames := strings.Split(plainPath, "/")
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for _, plainName := range plainNames {
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iv, _ := be.DirIVCache.Lookup(plainWD)
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if iv == nil {
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iv, err = ReadDirIV(filepath.Join(rootDir, cipherWD))
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if err != nil {
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return "", err
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}
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be.DirIVCache.Store(plainWD, iv, cipherWD)
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}
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cipherName := be.EncryptAndHashName(plainName, iv)
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cipherWD = filepath.Join(cipherWD, cipherName)
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plainWD = filepath.Join(plainWD, plainName)
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}
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return cipherWD, nil
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}
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// Dir is like filepath.Dir but returns "" instead of ".".
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func Dir(path string) string {
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d := filepath.Dir(path)
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@ -74,11 +74,10 @@ func (n *NameTransform) DecryptName(cipherName string, iv []byte) (string, error
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}
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// EncryptName encrypts "plainName", returns a base64-encoded "cipherName64".
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// Used internally by EncryptPathDirIV().
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// The encryption is either CBC or EME, depending on "useEME".
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//
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// This function is exported because fusefrontend needs access to the full (not hashed)
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// name if longname is used. Otherwise you should use EncryptPathDirIV()
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// This function is exported because in some cases, fusefrontend needs access
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// to the full (not hashed) name if longname is used.
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func (n *NameTransform) EncryptName(plainName string, iv []byte) (cipherName64 string) {
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bin := []byte(plainName)
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bin = pad16(bin)
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