package fusefrontend_reverse import ( "encoding/base64" "path/filepath" "strings" "syscall" "github.com/rfjakob/gocryptfs/internal/nametransform" "github.com/rfjakob/gocryptfs/internal/pathiv" "github.com/rfjakob/gocryptfs/internal/syscallcompat" "github.com/rfjakob/gocryptfs/internal/tlog" ) // abs basically returns storage dir + "/" + relPath. // It takes an error parameter so it can directly wrap decryptPath like this: // a, err := rfs.abs(rfs.decryptPath(relPath)) // abs never generates an error on its own. In other words, abs(p, nil) never // fails. func (rfs *ReverseFS) abs(relPath string, err error) (string, error) { if err != nil { return "", err } return filepath.Join(rfs.args.Cipherdir, relPath), nil } func (rfs *ReverseFS) rDecryptName(cName string, dirIV []byte, pDir string) (pName string, err error) { nameType := nametransform.NameType(cName) if nameType == nametransform.LongNameNone { pName, err = rfs.nameTransform.DecryptName(cName, dirIV) if err != nil { // We get lots of decrypt requests for names like ".Trash" that // are invalid base64. Convert them to ENOENT so the correct // error gets returned to the user. if _, ok := err.(base64.CorruptInputError); ok { return "", syscall.ENOENT } // Stat attempts on the link target of encrypted symlinks. // These are always valid base64 but the length is not a // multiple of 16. if err == syscall.EBADMSG { return "", syscall.ENOENT } return "", err } } else if nameType == nametransform.LongNameContent { pName, err = rfs.findLongnameParent(pDir, dirIV, cName) if err != nil { return "", err } } else { // It makes no sense to decrypt a ".name" file. This is a virtual file // that has no representation in the plaintext filesystem. ".name" // files should have already been handled in virtualfile.go. tlog.Warn.Printf("rDecryptName: cannot decrypt virtual file %q", cName) return "", syscall.EINVAL } return pName, nil } func (rfs *ReverseFS) decryptPath(relPath string) (string, error) { if rfs.args.PlaintextNames || relPath == "" { return relPath, nil } // Check if the parent dir is in the cache cDir := nametransform.Dir(relPath) dirIV, pDir := rPathCache.lookup(cDir) if dirIV != nil { cName := filepath.Base(relPath) pName, err := rfs.rDecryptName(cName, dirIV, pDir) if err != nil { return "", err } return filepath.Join(pDir, pName), nil } parts := strings.Split(relPath, "/") var transformedParts []string for i := range parts { // Start at the top and recurse currentCipherDir := filepath.Join(parts[:i]...) currentPlainDir := filepath.Join(transformedParts[:i]...) dirIV = pathiv.Derive(currentCipherDir, pathiv.PurposeDirIV) transformedPart, err := rfs.rDecryptName(parts[i], dirIV, currentPlainDir) if err != nil { return "", err } transformedParts = append(transformedParts, transformedPart) } pRelPath := filepath.Join(transformedParts...) rPathCache.store(cDir, dirIV, nametransform.Dir(pRelPath)) return pRelPath, nil } // openBackingDir decrypt the relative ciphertext path "cRelPath", opens // the directory that contains the target file/dir and returns the fd to // the directory and the decrypted name of the target file. // The fd/name pair is intended for use with fchownat and friends. func (rfs *ReverseFS) openBackingDir(cRelPath string) (dirfd int, pName string, err error) { // Decrypt relative path pRelPath, err := rfs.decryptPath(cRelPath) if err != nil { return -1, "", err } // Open directory, safe against symlink races pDir := filepath.Dir(pRelPath) dirfd, err = syscallcompat.OpenNofollow(rfs.args.Cipherdir, pDir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) if err != nil { return -1, "", err } pName = filepath.Base(pRelPath) return dirfd, pName, nil }