longnames part I: Create and OpenDir work with long filenames > 176 bytes

Todo: Rename, Unlink, Rmdir, Mknod, Mkdir

11 files changed, 174 insertions, 39 deletions

diff --git a/internal/configfile/config_file.go b/internal/configfile/config_file.go
index 8c53a4b..0b910c0 100644
--- a/internal/configfile/config_file.go
+++ b/internal/configfile/config_file.go
@@ -56,6 +56,7 @@ func CreateConfFile(filename string, password string, plaintextNames bool, logN
 	} else {
 		cf.FeatureFlags = append(cf.FeatureFlags, FlagDirIV)
 		cf.FeatureFlags = append(cf.FeatureFlags, FlagEMENames)
+		cf.FeatureFlags = append(cf.FeatureFlags, FlagLongNames)
 	}
 
 	// Write file to disk
@@ -169,12 +170,13 @@ const (
 	FlagDirIV          = "DirIV"
 	FlagEMENames       = "EMENames"
 	FlagGCMIV128       = "GCMIV128"
+	FlagLongNames      = "LongNames"
 )
 
 // Verify that we understand a feature flag
 func (cf *ConfFile) isFeatureFlagKnown(flag string) bool {
 	switch flag {
-	case FlagPlaintextNames, FlagDirIV, FlagEMENames, FlagGCMIV128:
+	case FlagPlaintextNames, FlagDirIV, FlagEMENames, FlagGCMIV128, FlagLongNames:
 		return true
 	default:
 		return false
diff --git a/internal/fusefrontend/args.go b/internal/fusefrontend/args.go
index e8cab04..8520592 100644
--- a/internal/fusefrontend/args.go
+++ b/internal/fusefrontend/args.go
@@ -9,4 +9,5 @@ type Args struct {
 	DirIV          bool
 	EMENames       bool
 	GCMIV128       bool
+	LongNames      bool
 }
diff --git a/internal/fusefrontend/fs.go b/internal/fusefrontend/fs.go
index 007744c..a15e004 100644
--- a/internal/fusefrontend/fs.go
+++ b/internal/fusefrontend/fs.go
@@ -39,7 +39,7 @@ func NewFS(args Args) *FS {
 
 	cryptoCore := cryptocore.New(args.Masterkey, args.OpenSSL, args.GCMIV128)
 	contentEnc := contentenc.New(cryptoCore, contentenc.DefaultBS)
-	nameTransform := nametransform.New(cryptoCore, args.EMENames)
+	nameTransform := nametransform.New(cryptoCore, args.EMENames, args.LongNames)
 
 	return &FS{
 		FileSystem:    pathfs.NewLoopbackFileSystem(args.Cipherdir),
@@ -49,18 +49,6 @@ func NewFS(args Args) *FS {
 	}
 }
 
-// GetBackingPath - get the absolute encrypted path of the backing file
-// from the relative plaintext path "relPath"
-func (fs *FS) getBackingPath(relPath string) (string, error) {
-	cPath, err := fs.encryptPath(relPath)
-	if err != nil {
-		return "", err
-	}
-	cAbsPath := filepath.Join(fs.args.Cipherdir, cPath)
-	toggledlog.Debug.Printf("getBackingPath: %s + %s -> %s", fs.args.Cipherdir, relPath, cAbsPath)
-	return cAbsPath, nil
-}
-
 func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
 	toggledlog.Debug.Printf("FS.GetAttr('%s')", name)
 	if fs.isFiltered(name) {
@@ -97,10 +85,11 @@ func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, f
 	}
 	// Get DirIV (stays nil if DirIV if off)
 	var cachedIV []byte
+	var cDirAbsPath string
 	if fs.args.DirIV {
 		// Read the DirIV once and use it for all later name decryptions
-		cDirAbsPath := filepath.Join(fs.args.Cipherdir, cDirName)
-		cachedIV, err = fs.nameTransform.ReadDirIV(cDirAbsPath)
+		cDirAbsPath = filepath.Join(fs.args.Cipherdir, cDirName)
+		cachedIV, err = nametransform.ReadDirIV(cDirAbsPath)
 		if err != nil {
 			return nil, fuse.ToStatus(err)
 		}
@@ -117,14 +106,32 @@ func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, f
 			// silently ignore "gocryptfs.diriv" everywhere if dirIV is enabled
 			continue
 		}
-		var name string = cName
-		if !fs.args.PlaintextNames {
-			name, err = fs.nameTransform.DecryptName(cName, cachedIV)
-			if err != nil {
-				toggledlog.Warn.Printf("Invalid name \"%s\" in dir \"%s\": %s", cName, cDirName, err)
+
+		if fs.args.PlaintextNames {
+			plain = append(plain, cipherEntries[i])
+			continue
+		}
+
+		if fs.args.LongNames {
+			isLong := nametransform.IsLongName(cName)
+			if isLong == 1 {
+				cNameLong, err := nametransform.ReadLongName(filepath.Join(cDirAbsPath, cName))
+				if err != nil {
+					toggledlog.Warn.Printf("Could not read long name for file %s, skipping file", cName)
+					continue
+				}
+				cName = cNameLong
+			} else if isLong == 2 {
+				// ignore "gocryptfs.longname.*.name"
 				continue
 			}
 		}
+		name, err := fs.nameTransform.DecryptName(cName, cachedIV)
+		if err != nil {
+			toggledlog.Warn.Printf("Skipping invalid name '%s' in dir '%s': %s", cName, cDirName, err)
+			continue
+		}
+
 		cipherEntries[i].Name = name
 		plain = append(plain, cipherEntries[i])
 	}
@@ -172,6 +179,13 @@ func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Conte
 	if err != nil {
 		return nil, fuse.ToStatus(err)
 	}
+	cBaseName := filepath.Base(cPath)
+	if fs.args.LongNames && nametransform.IsLongName(cBaseName) == 1 {
+		err = fs.nameTransform.WriteLongName(filepath.Dir(cPath), cBaseName, filepath.Base(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)
diff --git a/internal/fusefrontend/names.go b/internal/fusefrontend/names.go
index 5760c87..e913792 100644
--- a/internal/fusefrontend/names.go
+++ b/internal/fusefrontend/names.go
@@ -3,8 +3,10 @@ package fusefrontend
 // This file forwards file encryption operations to cryptfs
 
 import (
+	"path/filepath"
+
 	"github.com/rfjakob/gocryptfs/internal/configfile"
-	mylog "github.com/rfjakob/gocryptfs/internal/toggledlog"
+	"github.com/rfjakob/gocryptfs/internal/toggledlog"
 )
 
 // isFiltered - check if plaintext "path" should be forbidden
@@ -16,7 +18,7 @@ func (fs *FS) isFiltered(path string) bool {
 	}
 	// gocryptfs.conf in the root directory is forbidden
 	if path == configfile.ConfDefaultName {
-		mylog.Info.Printf("The name /%s is reserved when -plaintextnames is used\n",
+		toggledlog.Info.Printf("The name /%s is reserved when -plaintextnames is used\n",
 			configfile.ConfDefaultName)
 		return true
 	}
@@ -25,6 +27,18 @@ func (fs *FS) isFiltered(path string) bool {
 	return false
 }
 
+// GetBackingPath - get the absolute encrypted path of the backing file
+// from the relative plaintext path "relPath"
+func (fs *FS) getBackingPath(relPath string) (string, error) {
+	cPath, err := fs.encryptPath(relPath)
+	if err != nil {
+		return "", err
+	}
+	cAbsPath := filepath.Join(fs.args.Cipherdir, cPath)
+	toggledlog.Debug.Printf("getBackingPath: %s + %s -> %s", fs.args.Cipherdir, relPath, cAbsPath)
+	return cAbsPath, nil
+}
+
 // encryptPath - encrypt relative plaintext path
 func (fs *FS) encryptPath(plainPath string) (string, error) {
 	if fs.args.PlaintextNames {
@@ -34,8 +48,10 @@ func (fs *FS) encryptPath(plainPath string) (string, error) {
 		return fs.nameTransform.EncryptPathNoIV(plainPath), nil
 	}
 	fs.dirIVLock.RLock()
-	defer fs.dirIVLock.RUnlock()
-	return fs.nameTransform.EncryptPathDirIV(plainPath, fs.args.Cipherdir)
+	cPath, err := fs.nameTransform.EncryptPathDirIV(plainPath, fs.args.Cipherdir)
+	toggledlog.Debug.Printf("encryptPath '%s' -> '%s' (err: %v)", plainPath, cPath, err)
+	fs.dirIVLock.RUnlock()
+	return cPath, err
 }
 
 // decryptPath - decrypt relative ciphertext path
@@ -48,5 +64,5 @@ func (fs *FS) decryptPath(cipherPath string) (string, error) {
 	}
 	fs.dirIVLock.RLock()
 	defer fs.dirIVLock.RUnlock()
-	return fs.nameTransform.DecryptPathDirIV(cipherPath, fs.args.Cipherdir, fs.args.EMENames)
+	return fs.nameTransform.DecryptPathDirIV(cipherPath, fs.args.Cipherdir)
 }
diff --git a/internal/nametransform/longnames.go b/internal/nametransform/longnames.go
new file mode 100644
index 0000000..e442b64
--- /dev/null
+++ b/internal/nametransform/longnames.go
@@ -0,0 +1,68 @@
+package nametransform
+
+import (
+	"syscall"
+	"path/filepath"
+	"io/ioutil"
+	"crypto/sha256"
+	"encoding/base64"
+	"strings"
+
+	"github.com/rfjakob/gocryptfs/internal/toggledlog"
+)
+
+// Files with long names are stored in two files:
+// gocryptfs.longname.[sha256]       <--- File content
+// gocryptfs.longname.[sha256].name  <--- File name
+const longNamePrefix = "gocryptfs.longname."
+const longNameSuffix = ".name"
+
+// HashLongName - take the hash of a long string "name" and return
+// "gocryptfs.longname.[sha256]"
+func HashLongName(name string) string {
+	hashBin := sha256.Sum256([]byte(name))
+	hashBase64 := base64.URLEncoding.EncodeToString(hashBin[:])
+	return longNamePrefix + hashBase64
+}
+
+// IsLongName - detect if cName is
+// gocryptfs.longname.* ........ 1
+// gocryptfs.longname.*.name ... 2
+// else ........................ 0
+func IsLongName(cName string) int {
+	if !strings.HasPrefix(cName, longNamePrefix) {
+		return 0
+	}
+	if strings.HasSuffix(cName, longNameSuffix) {
+		return 2
+	}
+	return 1
+}
+
+// ReadLongName - read "path".name
+func ReadLongName(path string) (string, error) {
+	content, err := ioutil.ReadFile(path+longNameSuffix)
+	if err != nil {
+		toggledlog.Warn.Printf("ReadLongName: %v", err)
+	}
+	return string(content), err
+}
+
+// WriteLongName -
+func (n *NameTransform) WriteLongName(cDir string, hashedName string, plainName string) (err error) {
+	if len(plainName) > syscall.NAME_MAX {
+		return syscall.ENAMETOOLONG
+	}
+
+	dirIV, err := ReadDirIV(cDir)
+	if err != nil {
+		toggledlog.Warn.Printf("WriteLongName: %v", err)
+		return err
+	}
+	cName := n.EncryptName(plainName, dirIV)
+	err = ioutil.WriteFile(filepath.Join(cDir, hashedName + longNameSuffix), []byte(cName), 0600)
+	if err != nil {
+		toggledlog.Warn.Printf("WriteLongName: %v", err)
+	}
+	return err
+}
diff --git a/internal/nametransform/longnames_test.go b/internal/nametransform/longnames_test.go
new file mode 100644
index 0000000..dc4098c
--- /dev/null
+++ b/internal/nametransform/longnames_test.go
@@ -0,0 +1,22 @@
+package nametransform
+
+import (
+	"testing"
+)
+
+func TestIsLongName(t *testing.T) {
+	n := "gocryptfs.longname.LkwUdALvV_ANnzQN6ZZMYnxxfARD3IeZWCKnxGJjYmU=.name"
+	if IsLongName(n) != 2 {
+		t.Errorf("False negative")
+	}
+
+	n = "gocryptfs.longname.LkwUdALvV_ANnzQN6ZZMYnxxfARD3IeZWCKnxGJjYmU="
+	if IsLongName(n) != 1 {
+		t.Errorf("False negative")
+	}
+
+	n = "LkwUdALvV_ANnzQN6ZZMYnxxfARD3IeZWCKnxGJjYmU="
+	if IsLongName(n) != 0 {
+		t.Errorf("False positive")
+	}
+}
diff --git a/internal/nametransform/name_api.go b/internal/nametransform/name_api.go
index fe68e09..391a5ce 100644
--- a/internal/nametransform/name_api.go
+++ b/internal/nametransform/name_api.go
@@ -5,12 +5,14 @@ import "github.com/rfjakob/gocryptfs/internal/cryptocore"
 type NameTransform struct {
 	cryptoCore *cryptocore.CryptoCore
 	useEME     bool
+	longNames  bool
 	DirIVCache dirIVCache
 }
 
-func New(c *cryptocore.CryptoCore, useEME bool) *NameTransform {
+func New(c *cryptocore.CryptoCore, useEME bool, longNames bool) *NameTransform {
 	return &NameTransform{
 		cryptoCore: c,
+		longNames: longNames,
 		useEME:     useEME,
 	}
 }
diff --git a/internal/nametransform/names_core.go b/internal/nametransform/names_core.go
index 2eb0026..779b885 100644
--- a/internal/nametransform/names_core.go
+++ b/internal/nametransform/names_core.go
@@ -45,7 +45,10 @@ func (n *NameTransform) DecryptName(cipherName string, iv []byte) (string, error
 
 // encryptName - encrypt "plainName", return base64-encoded "cipherName64"
 // The used encryption is either CBC or EME, depending on "useEME".
-func (n *NameTransform) encryptName(plainName string, iv []byte) (cipherName64 string) {
+//
+// This function is exported because fusefrontend needs access to the full (not hashed)
+// name if longname is used
+func (n *NameTransform) EncryptName(plainName string, iv []byte) (cipherName64 string) {
 
 	bin := []byte(plainName)
 	bin = pad16(bin)
diff --git a/internal/nametransform/names_diriv.go b/internal/nametransform/names_diriv.go
index 94c41c8..d45f91b 100644
--- a/internal/nametransform/names_diriv.go
+++ b/internal/nametransform/names_diriv.go
@@ -1,6 +1,7 @@
 package nametransform
 
 import (
+	"syscall"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -19,8 +20,9 @@ const (
 	DirIVFilename = "gocryptfs.diriv"
 )
 
-// readDirIV - read the "gocryptfs.diriv" file from "dir" (absolute ciphertext path)
-func (be *NameTransform) ReadDirIV(dir string) (iv []byte, readErr error) {
+// ReadDirIV - read the "gocryptfs.diriv" file from "dir" (absolute ciphertext path)
+// This function is exported because it allows for an efficient readdir implementation
+func ReadDirIV(dir string) (iv []byte, readErr error) {
 	ivfile := filepath.Join(dir, DirIVFilename)
 	toggledlog.Debug.Printf("ReadDirIV: reading %s\n", ivfile)
 	iv, readErr = ioutil.ReadFile(ivfile)
@@ -62,9 +64,11 @@ func (be *NameTransform) EncryptPathDirIV(plainPath string, rootDir string) (cip
 	parentDir := filepath.Dir(plainPath)
 	found, iv, cParentDir := be.DirIVCache.lookup(parentDir)
 	if found {
-		//fmt.Print("h")
 		baseName := filepath.Base(plainPath)
-		cBaseName := be.encryptName(baseName, iv)
+		cBaseName := be.EncryptName(baseName, iv)
+		if be.longNames && len(cBaseName) > syscall.NAME_MAX {
+			cBaseName = HashLongName(cBaseName)
+		}
 		cipherPath = cParentDir + "/" + cBaseName
 		return cipherPath, nil
 	}
@@ -73,29 +77,32 @@ func (be *NameTransform) EncryptPathDirIV(plainPath string, rootDir string) (cip
 	var encryptedNames []string
 	plainNames := strings.Split(plainPath, "/")
 	for _, plainName := range plainNames {
-		iv, err = be.ReadDirIV(wd)
+		iv, err = ReadDirIV(wd)
 		if err != nil {
 			return "", err
 		}
-		encryptedName := be.encryptName(plainName, iv)
+		encryptedName := be.EncryptName(plainName, iv)
+		if be.longNames && len(encryptedName) > syscall.NAME_MAX {
+			encryptedName = HashLongName(encryptedName)
+		}
 		encryptedNames = append(encryptedNames, encryptedName)
 		wd = filepath.Join(wd, encryptedName)
 	}
-	// Cache the final DirIV
 	cipherPath = strings.Join(encryptedNames, "/")
+	// Cache the final DirIV
 	cParentDir = filepath.Dir(cipherPath)
 	be.DirIVCache.store(parentDir, iv, cParentDir)
 	return cipherPath, nil
 }
 
 // DecryptPathDirIV - decrypt path using EME with DirIV
-func (be *NameTransform) DecryptPathDirIV(encryptedPath string, rootDir string, eme bool) (string, error) {
+func (be *NameTransform) DecryptPathDirIV(encryptedPath string, rootDir string) (string, error) {
 	var wd = rootDir
 	var plainNames []string
 	encryptedNames := strings.Split(encryptedPath, "/")
 	toggledlog.Debug.Printf("DecryptPathDirIV: decrypting %v\n", encryptedNames)
 	for _, encryptedName := range encryptedNames {
-		iv, err := be.ReadDirIV(wd)
+		iv, err := ReadDirIV(wd)
 		if err != nil {
 			return "", err
 		}
diff --git a/internal/nametransform/names_noiv.go b/internal/nametransform/names_noiv.go
index f301e52..f1009e4 100644
--- a/internal/nametransform/names_noiv.go
+++ b/internal/nametransform/names_noiv.go
@@ -49,7 +49,7 @@ func (be *NameTransform) translatePathNoIV(path string, op int) (string, error)
 		}
 		var newPart string
 		if op == OpEncrypt {
-			newPart = be.encryptName(part, zeroIV)
+			newPart = be.EncryptName(part, zeroIV)
 		} else {
 			newPart, err = be.DecryptName(part, zeroIV)
 			if err != nil {
diff --git a/internal/nametransform/names_test.go b/internal/nametransform/names_test.go
index fdb9f05..4a0043b 100644
--- a/internal/nametransform/names_test.go
+++ b/internal/nametransform/names_test.go
@@ -15,7 +15,7 @@ func TestEncryptPathNoIV(t *testing.T) {
 
 	key := make([]byte, cryptocore.KeyLen)
 	cc := cryptocore.New(key, false, true)
-	fs := New(cc, true)
+	fs := New(cc, true, false)
 
 	for _, n := range s {
 		c := fs.EncryptPathNoIV(n)