diriv: Convert filename encryption users to diriv

6 files changed, 219 insertions, 79 deletions

diff --git a/cryptfs/cryptfs_names.go b/cryptfs/cryptfs_names.go
index 1282f53..37a769f 100644
--- a/cryptfs/cryptfs_names.go
+++ b/cryptfs/cryptfs_names.go
@@ -12,15 +12,15 @@ import (
 )
 
 const (
-	ENCRYPT = true
-	DECRYPT = false
+	OpEncrypt = iota
+	OpDecrypt
 )
 
-// DecryptName - decrypt filename
-func (be *CryptFS) decryptName(cipherName string) (string, error) {
+// DecryptName - decrypt base64-encoded encrypted filename "cipherName"
+func (be *CryptFS) decryptName(cipherName string, iv []byte) (string, error) {
 
 	// Make sure relative symlinks still work after encryption
-	// by passing these trough unchanged
+	// by passing these through unchanged
 	if cipherName == "." || cipherName == ".." {
 		return cipherName, nil
 	}
@@ -34,7 +34,6 @@ func (be *CryptFS) decryptName(cipherName string) (string, error) {
 		return "", fmt.Errorf("Decoded length %d is not a multiple of the AES block size", len(bin))
 	}
 
-	iv := make([]byte, aes.BlockSize) // TODO ?
 	cbc := cipher.NewCBCDecrypter(be.blockCipher, iv)
 	cbc.CryptBlocks(bin, bin)
 
@@ -48,7 +47,7 @@ func (be *CryptFS) decryptName(cipherName string) (string, error) {
 }
 
 // EncryptName - encrypt filename
-func (be *CryptFS) encryptName(plainName string) string {
+func (be *CryptFS) encryptName(plainName string, iv []byte) string {
 
 	// Make sure relative symlinks still work after encryption
 	// by passing these trough unchanged
@@ -59,7 +58,6 @@ func (be *CryptFS) encryptName(plainName string) string {
 	bin := []byte(plainName)
 	bin = be.pad16(bin)
 
-	iv := make([]byte, 16) // TODO ?
 	cbc := cipher.NewCBCEncrypter(be.blockCipher, iv)
 	cbc.CryptBlocks(bin, bin)
 
@@ -67,9 +65,10 @@ func (be *CryptFS) encryptName(plainName string) string {
 	return cipherName64
 }
 
-// TranslatePath - encrypt or decrypt path. Just splits the string on "/"
-// and hands the parts to EncryptName() / DecryptName()
-func (be *CryptFS) translatePath(path string, op bool) (string, error) {
+
+// TranslatePathZeroIV - encrypt or decrypt path using CBC with a constant all-zero IV.
+// Just splits the string on "/" and hands the parts to encryptName() / decryptName()
+func (be *CryptFS) TranslatePathZeroIV(path string, op int) (string, error) {
 	var err error
 
 	// Empty string means root directory
@@ -77,6 +76,8 @@ func (be *CryptFS) translatePath(path string, op bool) (string, error) {
 		return path, err
 	}
 
+	zeroIV := make([]byte, DIRIV_LEN)
+
 	// Run operation on each path component
 	var translatedParts []string
 	parts := strings.Split(path, "/")
@@ -88,10 +89,10 @@ func (be *CryptFS) translatePath(path string, op bool) (string, error) {
 			continue
 		}
 		var newPart string
-		if op == ENCRYPT {
-			newPart = be.encryptName(part)
+		if op == OpEncrypt {
+			newPart = be.encryptName(part, zeroIV)
 		} else {
-			newPart, err = be.decryptName(part)
+			newPart, err = be.decryptName(part, zeroIV)
 			if err != nil {
 				return "", err
 			}
@@ -102,23 +103,6 @@ func (be *CryptFS) translatePath(path string, op bool) (string, error) {
 	return strings.Join(translatedParts, "/"), err
 }
 
-// EncryptPath - encrypt filename or path. Just hands it to translatePath().
-func (be *CryptFS) EncryptPath(path string) string {
-	if be.plaintextNames {
-		return path
-	}
-	newPath, _ := be.translatePath(path, ENCRYPT)
-	return newPath
-}
-
-// DecryptPath - decrypt filename or path. Just hands it to translatePath().
-func (be *CryptFS) DecryptPath(path string) (string, error) {
-	if be.plaintextNames {
-		return path, nil
-	}
-	return be.translatePath(path, DECRYPT)
-}
-
 // pad16 - pad filename to 16 byte blocks using standard PKCS#7 padding
 // https://tools.ietf.org/html/rfc5652#section-6.3
 func (be *CryptFS) pad16(orig []byte) (padded []byte) {
@@ -171,3 +155,5 @@ func (be *CryptFS) unPad16(orig []byte) ([]byte, error) {
 	}
 	return orig[0:newLen], nil
 }
+
+
diff --git a/cryptfs/names_diriv.go b/cryptfs/names_diriv.go
new file mode 100644
index 0000000..c9debab
--- /dev/null
+++ b/cryptfs/names_diriv.go
@@ -0,0 +1,69 @@
+package cryptfs
+
+import (
+	"path/filepath"
+	"io/ioutil"
+	"fmt"
+	"strings"
+)
+
+// readDirIV - read the "gocryptfs.diriv" file from "dir" (absolute path)
+func (be *CryptFS) readDirIV(dir string) (iv []byte, err error) {
+		ivfile := filepath.Join(dir, DIRIV_FILENAME)
+		iv, err = ioutil.ReadFile(ivfile)
+		if err != nil {
+			Warn.Printf("readDirIV: %v\n", err)
+			return nil, err
+		}
+		if len(iv) != DIRIV_LEN {
+			return nil, fmt.Errorf("readDirIV: Invalid length %d\n", len(iv))
+		}
+		return iv, nil
+}
+
+// EncryptPathDirIV - encrypt path using CBC with DirIV
+func (be *CryptFS) EncryptPathDirIV(plainPath string, rootDir string) (string, error) {
+	if be.plaintextNames {
+		return plainPath, nil
+	}
+	// Empty string means root directory
+	if plainPath == "" {
+		return plainPath, nil
+	}
+	var wd = rootDir
+	var encryptedNames []string
+	plainNames := strings.Split(plainPath, "/")
+	for _, plainName := range plainNames {
+		iv, err := be.readDirIV(wd)
+		if err != nil {
+			return "", err
+		}
+		encryptedName := be.encryptName(plainName, iv)
+		encryptedNames = append(encryptedNames, encryptedName)
+		wd = filepath.Join(wd, encryptedName)
+	}
+	return filepath.Join(encryptedNames...), nil
+}
+
+// DecryptPathDirIV - encrypt path using CBC with DirIV
+func (be *CryptFS) DecryptPathDirIV(encryptedPath string, rootDir string) (string, error) {
+	if be.plaintextNames {
+		return encryptedPath, nil
+	}
+	var wd = rootDir
+	var plainNames []string
+	encryptedNames := strings.Split(encryptedPath, "/")
+	for _, encryptedName := range encryptedNames {
+		iv, err := be.readDirIV(wd)
+		if err != nil {
+			return "", err
+		}
+		plainName, err := be.decryptName(encryptedName, iv)
+		if err != nil {
+			return "", err
+		}
+		plainNames = append(plainNames, plainName)
+		wd = filepath.Join(wd, encryptedName)
+	}
+	return filepath.Join(plainNames...), nil
+}
diff --git a/cryptfs/names_test.go b/cryptfs/names_test.go
index ccf08df..1ad3391 100644
--- a/cryptfs/names_test.go
+++ b/cryptfs/names_test.go
@@ -15,8 +15,8 @@ func TestTranslatePath(t *testing.T) {
 	fs := NewCryptFS(key, true, false)
 
 	for _, n := range s {
-		c := fs.EncryptPath(n)
-		d, err := fs.DecryptPath(c)
+		c, err := fs.TranslatePathZeroIV(n, OpEncrypt)
+		d, err := fs.TranslatePathZeroIV(c, OpDecrypt)
 		if err != nil {
 			t.Errorf("Got error from DecryptName: %s", err)
 		}
diff --git a/integration_tests/main_test.go b/integration_tests/main_test.go
index 4b2c11e..e46e2e4 100644
--- a/integration_tests/main_test.go
+++ b/integration_tests/main_test.go
@@ -60,16 +60,18 @@ func TestMain(m *testing.M) {
 func testWriteN(t *testing.T, fn string, n int) string {
 	file, err := os.Create(defaultPlainDir + fn)
 	if err != nil {
-		t.FailNow()
+		t.Fatal(err)
 	}
 
 	d := make([]byte, n)
 	written, err := file.Write(d)
 	if err != nil || written != len(d) {
-		fmt.Printf("err=\"%s\", written=%d\n", err, written)
-		t.Fail()
+		t.Errorf("err=\"%s\", written=%d\n", err, written)
+	}
+	err = file.Close()
+	if err != nil {
+		t.Error(err)
 	}
-	file.Close()
 
 	verifySize(t, defaultPlainDir+fn, n)
 
diff --git a/pathfs_frontend/fs.go b/pathfs_frontend/fs.go
index 9c809df..48ea4a2 100644
--- a/pathfs_frontend/fs.go
+++ b/pathfs_frontend/fs.go
@@ -1,6 +1,7 @@
 package pathfs_frontend
 
 import (
+	"encoding/base64"
 	"fmt"
 	"sync"
 	"syscall"
@@ -17,9 +18,9 @@ import (
 
 type FS struct {
 	*cryptfs.CryptFS
-	pathfs.FileSystem        // loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
-	backing           string // Backing directory
-	dirivLock sync.RWMutex   // Global lock that is taken if any "gocryptfs.diriv" file is modified
+	pathfs.FileSystem           // loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
+	backingDir           string // Backing directory, cipherdir
+	dirivLock sync.RWMutex      // Global lock that is taken if any "gocryptfs.diriv" file is modified
 }
 
 // Encrypted FUSE overlay filesystem
@@ -27,14 +28,18 @@ func NewFS(key []byte, backing string, useOpenssl bool, plaintextNames bool) *FS
 	return &FS{
 		CryptFS:    cryptfs.NewCryptFS(key, useOpenssl, plaintextNames),
 		FileSystem: pathfs.NewLoopbackFileSystem(backing),
-		backing:    backing,
+		backingDir:    backing,
 	}
 }
 
-// GetPath - get the absolute encrypted path of the backing file
+// GetBackingPath - get the absolute encrypted path of the backing file
 // from the relative plaintext path "relPath"
-func (fs *FS) GetPath(relPath string) string {
-	return filepath.Join(fs.backing, fs.EncryptPath(relPath))
+func (fs *FS) getBackingPath(relPath string) (string, error) {
+	encrypted, err := fs.encryptPath(relPath)
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(fs.backingDir, encrypted), nil
 }
 
 func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
@@ -42,7 +47,10 @@ func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Stat
 	if fs.CryptFS.IsFiltered(name) {
 		return nil, fuse.EPERM
 	}
-	cName := fs.EncryptPath(name)
+	cName, err := fs.encryptPath(name)
+	if err != nil {
+		return nil, fuse.ToStatus(err)
+	}
 	a, status := fs.FileSystem.GetAttr(cName, context)
 	if a == nil {
 		cryptfs.Debug.Printf("FS.GetAttr failed: %s\n", status.String())
@@ -59,7 +67,11 @@ func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Stat
 
 func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, fuse.Status) {
 	cryptfs.Debug.Printf("OpenDir(%s)\n", dirName)
-	cipherEntries, status := fs.FileSystem.OpenDir(fs.EncryptPath(dirName), context)
+	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 {
@@ -72,7 +84,7 @@ func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, f
 				// silently ignore "gocryptfs.diriv" everywhere
 				continue
 			}
-			name, err := fs.DecryptPath(cName)
+			name, err := fs.decryptPath(cName)
 			if err != nil {
 				cryptfs.Warn.Printf("Invalid name \"%s\" in dir \"%s\": %s\n", cName, dirName, err)
 				continue
@@ -103,7 +115,11 @@ func (fs *FS) Open(path string, flags uint32, context *fuse.Context) (fuseFile n
 		return nil, fuse.EPERM
 	}
 	iflags, writeOnly := fs.mangleOpenFlags(flags)
-	f, err := os.OpenFile(fs.GetPath(path), iflags, 0666)
+	cPath, err := fs.getBackingPath(path)
+	if err != nil {
+		return nil, fuse.ToStatus(err)
+	}
+	f, err := os.OpenFile(cPath, iflags, 0666)
 	if err != nil {
 		return nil, fuse.ToStatus(err)
 	}
@@ -116,7 +132,11 @@ func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Conte
 		return nil, fuse.EPERM
 	}
 	iflags, writeOnly := fs.mangleOpenFlags(flags)
-	f, err := os.OpenFile(fs.GetPath(path), iflags|os.O_CREATE, os.FileMode(mode))
+	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)
 	}
@@ -127,21 +147,33 @@ func (fs *FS) Chmod(path string, mode uint32, context *fuse.Context) (code fuse.
 	if fs.CryptFS.IsFiltered(path) {
 		return fuse.EPERM
 	}
-	return fs.FileSystem.Chmod(fs.EncryptPath(path), mode, context)
+	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) {
 	if fs.CryptFS.IsFiltered(path) {
 		return fuse.EPERM
 	}
-	return fs.FileSystem.Chown(fs.EncryptPath(path), uid, gid, context)
+	cPath, err := fs.encryptPath(path)
+	if err != nil {
+		return fuse.ToStatus(err)
+	}
+	return fs.FileSystem.Chown(cPath, uid, gid, context)
 }
 
-func (fs *FS) Mknod(name string, mode uint32, dev uint32, context *fuse.Context) (code fuse.Status) {
-	if fs.CryptFS.IsFiltered(name) {
+func (fs *FS) Mknod(path string, mode uint32, dev uint32, context *fuse.Context) (code fuse.Status) {
+	if fs.CryptFS.IsFiltered(path) {
 		return fuse.EPERM
 	}
-	return fs.FileSystem.Mknod(fs.EncryptPath(name), mode, dev, context)
+	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) {
@@ -153,15 +185,23 @@ func (fs *FS) Utimens(path string, Atime *time.Time, Mtime *time.Time, context *
 	if fs.CryptFS.IsFiltered(path) {
 		return fuse.EPERM
 	}
-	return fs.FileSystem.Utimens(fs.EncryptPath(path), Atime, Mtime, context)
+	cPath, err := fs.encryptPath(path)
+	if err != nil {
+		return fuse.ToStatus(err)
+	}
+	return fs.FileSystem.Utimens(cPath, Atime, Mtime, context)
 }
 
-func (fs *FS) Readlink(name string, context *fuse.Context) (out string, status fuse.Status) {
-	dst, status := fs.FileSystem.Readlink(fs.EncryptPath(name), 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)
+	}
+	dst, status := fs.FileSystem.Readlink(cPath, context)
 	if status != fuse.OK {
 		return "", status
 	}
-	dstPlain, err := fs.DecryptPath(dst)
+	dstPlain, err := fs.decryptPath(dst)
 	if err != nil {
 		cryptfs.Warn.Printf("Failed decrypting symlink: %s\n", err.Error())
 		return "", fuse.EIO
@@ -173,11 +213,14 @@ func (fs *FS) Mkdir(relPath string, mode uint32, context *fuse.Context) (code fu
 	if fs.CryptFS.IsFiltered(relPath) {
 		return fuse.EPERM
 	}
-	encPath := fs.GetPath(relPath)
+	encPath, err := fs.getBackingPath(relPath)
+	if err != nil {
+		return fuse.ToStatus(err)
+	}
 	diriv := cryptfs.RandBytes(cryptfs.DIRIV_LEN)
 	dirivPath := filepath.Join(encPath, cryptfs.DIRIV_FILENAME)
 	// Create directory
-	err := os.Mkdir(encPath, os.FileMode(mode))
+	err = os.Mkdir(encPath, os.FileMode(mode))
 	if err != nil {
 		return fuse.ToStatus(err)
 	}
@@ -196,20 +239,22 @@ func (fs *FS) Mkdir(relPath string, mode uint32, context *fuse.Context) (code fu
 	return fuse.OK
 }
 
-func (fs *FS) Unlink(name string, context *fuse.Context) (code fuse.Status) {
-	if fs.CryptFS.IsFiltered(name) {
+func (fs *FS) Unlink(path string, context *fuse.Context) (code fuse.Status) {
+	if fs.CryptFS.IsFiltered(path) {
 		return fuse.EPERM
 	}
-	cName := fs.EncryptPath(name)
-	code = fs.FileSystem.Unlink(cName, context)
-	if code != fuse.OK {
-		cryptfs.Debug.Printf("Unlink failed on %s [%s], code=%s\n", name, cName, code.String())
+	cPath, err := fs.getBackingPath(path)
+	if err != nil {
+		return fuse.ToStatus(err)
 	}
-	return code
+	return fuse.ToStatus(syscall.Unlink(cPath))
 }
 
 func (fs *FS) Rmdir(name string, context *fuse.Context) (code fuse.Status) {
-	encPath := fs.GetPath(name)
+	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.
@@ -264,34 +309,61 @@ func (fs *FS) Rmdir(name string, context *fuse.Context) (code fuse.Status) {
 	return fuse.OK
 }
 
-func (fs *FS) Symlink(pointedTo string, linkName string, context *fuse.Context) (code fuse.Status) {
+func (fs *FS) Symlink(target string, linkName string, context *fuse.Context) (code fuse.Status) {
+	cryptfs.Debug.Printf("Symlink(\"%s\", \"%s\")\n", target, linkName)
 	if fs.CryptFS.IsFiltered(linkName) {
 		return fuse.EPERM
 	}
-	// TODO symlink encryption
-	cryptfs.Debug.Printf("Symlink(\"%s\", \"%s\")\n", pointedTo, linkName)
-	return fs.FileSystem.Symlink(fs.EncryptPath(pointedTo), fs.EncryptPath(linkName), context)
+	cName, err := fs.encryptPath(linkName)
+	if err != nil {
+		return fuse.ToStatus(err)
+	}
+
+	cBinTarget := fs.CryptFS.EncryptBlock([]byte(target), 0, nil)
+	cTarget := base64.URLEncoding.EncodeToString(cBinTarget)
+
+	return fuse.ToStatus(os.Symlink(cTarget, cName))
 }
 
 func (fs *FS) Rename(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) {
 	if fs.CryptFS.IsFiltered(newPath) {
 		return fuse.EPERM
 	}
-	return fs.FileSystem.Rename(fs.EncryptPath(oldPath), fs.EncryptPath(newPath), context)
+	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(orig string, newName string, context *fuse.Context) (code fuse.Status) {
-	if fs.CryptFS.IsFiltered(newName) {
+func (fs *FS) Link(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) {
+	if fs.CryptFS.IsFiltered(newPath) {
 		return fuse.EPERM
 	}
-	return fs.FileSystem.Link(fs.EncryptPath(orig), fs.EncryptPath(newName), context)
+	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(name string, mode uint32, context *fuse.Context) (code fuse.Status) {
-	if fs.CryptFS.IsFiltered(name) {
+func (fs *FS) Access(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
+	if fs.CryptFS.IsFiltered(path) {
 		return fuse.EPERM
 	}
-	return fs.FileSystem.Access(fs.EncryptPath(name), mode, context)
+	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) {
diff --git a/pathfs_frontend/names.go b/pathfs_frontend/names.go
new file mode 100644
index 0000000..5842d83
--- /dev/null
+++ b/pathfs_frontend/names.go
@@ -0,0 +1,11 @@
+package pathfs_frontend
+
+// This file handles filename encryption
+
+func (fs *FS) encryptPath(plainPath string) (string, error) {
+	return fs.CryptFS.EncryptPathDirIV(plainPath, fs.backingDir)
+}
+
+func (fs *FS) decryptPath(cipherPath string) (string, error) {
+	return fs.CryptFS.DecryptPathDirIV(cipherPath, fs.backingDir)
+}