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libgocryptfs
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Implement PlainTextNames mode 

Also, forbid access to "gocryptfs.conf" in the root dir.
This commit is contained in:
Jakob Unterwurzacher 2015-11-03 00:00:13 +01:00
parent 66db3ad086
commit de56fe9e35
5 changed files with 84 additions and 20 deletions
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4
cryptfs/config_file.go
View File

@ -76,7 +76,7 @@ func LoadConfFile(filename string, password string) ([]byte, *ConfFile, error) {
// Unlock master key using password-based key
// We use stock go GCM instead of OpenSSL here as speed is not important
// and we get better error messages
cfs := NewCryptFS(scryptHash, false)
cfs := NewCryptFS(scryptHash, false, false)
key, err := cfs.DecryptBlock(cf.EncryptedKey, 0, nil)
if err != nil {
Warn.Printf("failed to unlock master key: %s\n", err.Error())
@ -95,7 +95,7 @@ func (cf *ConfFile) EncryptKey(key []byte, password string) {
scryptHash := cf.ScryptObject.DeriveKey(password)
// Lock master key using password-based key
cfs := NewCryptFS(scryptHash, false)
cfs := NewCryptFS(scryptHash, false, false)
cf.EncryptedKey = cfs.EncryptBlock(key, 0, nil)
}

4
cryptfs/cryptfs.go
View File

@ -23,9 +23,10 @@ type CryptFS struct {
cipherBS uint64
// Stores an all-zero block of size cipherBS
allZeroBlock []byte
plaintextNames bool
}
func NewCryptFS(key []byte, useOpenssl bool) *CryptFS {
func NewCryptFS(key []byte, useOpenssl bool, plaintextNames bool) *CryptFS {
if len(key) != KEY_LEN {
panic(fmt.Sprintf("Unsupported key length %d", len(key)))
@ -54,6 +55,7 @@ func NewCryptFS(key []byte, useOpenssl bool) *CryptFS {
plainBS: DEFAULT_PLAINBS,
cipherBS: uint64(cipherBS),
allZeroBlock: make([]byte, cipherBS),
plaintextNames: plaintextNames,
}
}

10
cryptfs/cryptfs_names.go
View File

@ -102,14 +102,20 @@ 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().
// 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().
// 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)
}

18
main.go
View File

@ -41,7 +41,7 @@ func initDir(dirArg string, plaintextNames bool) {
err := checkDirEmpty(dir)
if err != nil {
fmt.Printf("Error: \"%s\": %v\n", dirArg, err)
fmt.Printf("Invalid CIPHERDIR: %v\n", err)
os.Exit(ERREXIT_INIT)
}
@ -114,8 +114,8 @@ func main() {
fmt.Printf("Openssl disabled\n")
}
if args.init {
if flag.NArg() != 1 {
fmt.Printf("Usage: %s --init CIPHERDIR\n", PROGRAM_NAME)
if flag.NArg() != 1 && args.plaintextnames == false {
fmt.Printf("Usage: %s --init [--plaintextnames] CIPHERDIR\n", PROGRAM_NAME)
os.Exit(ERREXIT_USAGE)
}
initDir(flag.Arg(0), args.plaintextnames) // does not return
@ -154,6 +154,7 @@ func main() {
key = parseMasterKey(args.masterkey)
fmt.Printf("Using explicit master key.\n")
} else {
// Load config file
cfname := filepath.Join(args.cipherdir, cryptfs.ConfDefaultName)
_, err = os.Stat(cfname)
if err != nil {
@ -194,7 +195,11 @@ func main() {
os.Exit(0)
}
srv := pathfsFrontend(key, args.cipherdir, args.mountpoint, args.fusedebug, args.openssl)
var plaintextNames bool
if cf != nil {
plaintextNames = cf.PlaintextNames
}
srv := pathfsFrontend(key, args.cipherdir, args.mountpoint, args.fusedebug, args.openssl, plaintextNames)
if args.zerokey == false && len(args.masterkey) == 0 {
printMasterKey(key)
@ -215,9 +220,10 @@ func main() {
// main returns with code 0
}
func pathfsFrontend(key []byte, cipherdir string, mountpoint string, debug bool, openssl bool) *fuse.Server {
func pathfsFrontend(key []byte, cipherdir string, mountpoint string,
debug bool, openssl bool, plaintextNames bool) *fuse.Server {
finalFs := pathfs_frontend.NewFS(key, cipherdir, openssl)
finalFs := pathfs_frontend.NewFS(key, cipherdir, openssl, plaintextNames)
pathFsOpts := &pathfs.PathNodeFsOptions{ClientInodes: true}
pathFs := pathfs.NewPathNodeFs(finalFs, pathFsOpts)
fuseOpts := &nodefs.Options{

68
pathfs_frontend/fs.go
View File

@ -19,9 +19,9 @@ type FS struct {
}
// Encrypted FUSE overlay filesystem
func NewFS(key []byte, backing string, useOpenssl bool) *FS {
func NewFS(key []byte, backing string, useOpenssl bool, plaintextNames bool) *FS {
return &FS{
CryptFS: cryptfs.NewCryptFS(key, useOpenssl),
CryptFS: cryptfs.NewCryptFS(key, useOpenssl, plaintextNames),
FileSystem: pathfs.NewLoopbackFileSystem(backing),
backing: backing,
}
@ -34,6 +34,9 @@ func (fs *FS) GetPath(relPath string) string {
func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
cryptfs.Debug.Printf("FS.GetAttr('%s')\n", name)
if name == cryptfs.ConfDefaultName {
return nil, fuse.EPERM // See comment in Open()
}
cName := fs.EncryptPath(name)
a, status := fs.FileSystem.GetAttr(cName, context)
if a == nil {
@ -56,12 +59,12 @@ func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, f
if cipherEntries != nil {
for i := range cipherEntries {
cName := cipherEntries[i].Name
if dirName == "" && cName == cryptfs.ConfDefaultName {
// ignore "gocryptfs.conf" in the top level dir
continue
}
name, err := fs.DecryptPath(cName)
if err != nil {
if dirName == "" && cName == cryptfs.ConfDefaultName {
// Silently ignore "gocryptfs.conf" in the top level dir
continue
}
fmt.Printf("Invalid name \"%s\" in dir \"%s\": %s\n", cName, name, err)
continue
}
@ -85,11 +88,18 @@ func (fs *FS) mangleOpenFlags(flags uint32) (newFlags int, writeOnly bool) {
return newFlags, writeOnly
}
func (fs *FS) Open(name string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
cryptfs.Debug.Printf("Open(%s)\n", name)
func (fs *FS) Open(path string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
cryptfs.Debug.Printf("Open(%s)\n", path)
if path == cryptfs.ConfDefaultName {
// "gocryptfs.conf" in the top level dir is forbidden
// to protect the config file of this filesystem if
// "--plaintextnames" is enabled
return nil, fuse.EPERM
}
iflags, writeOnly := fs.mangleOpenFlags(flags)
f, err := os.OpenFile(fs.GetPath(name), iflags, 0666)
f, err := os.OpenFile(fs.GetPath(path), iflags, 0666)
if err != nil {
return nil, fuse.ToStatus(err)
}
@ -98,6 +108,10 @@ func (fs *FS) Open(name string, flags uint32, context *fuse.Context) (fuseFile n
}
func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Context) (fuseFile nodefs.File, code fuse.Status) {
if path == cryptfs.ConfDefaultName {
return nil, fuse.EPERM // See comment in Open()
}
iflags, writeOnly := fs.mangleOpenFlags(flags)
f, err := os.OpenFile(fs.GetPath(path), iflags|os.O_CREATE, os.FileMode(mode))
if err != nil {
@ -107,14 +121,26 @@ func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Conte
}
func (fs *FS) Chmod(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
if path == cryptfs.ConfDefaultName {
return fuse.EPERM // See comment in Open()
}
return fs.FileSystem.Chmod(fs.EncryptPath(path), mode, context)
}
func (fs *FS) Chown(path string, uid uint32, gid uint32, context *fuse.Context) (code fuse.Status) {
if path == cryptfs.ConfDefaultName {
return fuse.EPERM // See comment in Open()
}
return fs.FileSystem.Chown(fs.EncryptPath(path), uid, gid, context)
}
func (fs *FS) Mknod(name string, mode uint32, dev uint32, context *fuse.Context) (code fuse.Status) {
if name == cryptfs.ConfDefaultName {
return fuse.EPERM // See comment in Open()
}
return fs.FileSystem.Mknod(fs.EncryptPath(name), mode, dev, context)
}
@ -124,6 +150,10 @@ func (fs *FS) Truncate(path string, offset uint64, context *fuse.Context) (code
}
func (fs *FS) Utimens(path string, Atime *time.Time, Mtime *time.Time, context *fuse.Context) (code fuse.Status) {
if path == cryptfs.ConfDefaultName {
return fuse.EPERM // See comment in Open()
}
return fs.FileSystem.Utimens(fs.EncryptPath(path), Atime, Mtime, context)
}
@ -141,10 +171,18 @@ func (fs *FS) Readlink(name string, context *fuse.Context) (out string, status f
}
func (fs *FS) Mkdir(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
if path == cryptfs.ConfDefaultName {
return fuse.EPERM // See comment in Open()
}
return fs.FileSystem.Mkdir(fs.EncryptPath(path), mode, context)
}
func (fs *FS) Unlink(name string, context *fuse.Context) (code fuse.Status) {
if name == cryptfs.ConfDefaultName {
return fuse.EPERM // See comment in Open()
}
cName := fs.EncryptPath(name)
code = fs.FileSystem.Unlink(cName, context)
if code != fuse.OK {
@ -158,16 +196,28 @@ func (fs *FS) Rmdir(name string, context *fuse.Context) (code fuse.Status) {
}
func (fs *FS) Symlink(pointedTo string, linkName string, context *fuse.Context) (code fuse.Status) {
if linkName == cryptfs.ConfDefaultName {
return fuse.EPERM // See comment in Open()
}
// TODO symlink encryption
cryptfs.Debug.Printf("Symlink(\"%s\", \"%s\")\n", pointedTo, linkName)
return fs.FileSystem.Symlink(fs.EncryptPath(pointedTo), fs.EncryptPath(linkName), context)
}
func (fs *FS) Rename(oldPath string, newPath string, context *fuse.Context) (codee fuse.Status) {
if newPath == cryptfs.ConfDefaultName {
return fuse.EPERM // See comment in Open()
}
return fs.FileSystem.Rename(fs.EncryptPath(oldPath), fs.EncryptPath(newPath), context)
}
func (fs *FS) Link(orig string, newName string, context *fuse.Context) (code fuse.Status) {
if newName == cryptfs.ConfDefaultName {
return fuse.EPERM // See comment in Open()
}
return fs.FileSystem.Link(fs.EncryptPath(orig), fs.EncryptPath(newName), context)
}