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libgocryptfs
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diriv: also support old CBC symlink

This commit is contained in:
Jakob Unterwurzacher 2015-11-28 16:52:57 +01:00
parent 01141f8b5e
commit 1fb349e97b
4 changed files with 70 additions and 26 deletions
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30
main.go
View File

@ -245,6 +245,7 @@ func main() {
}
// Get master key
var masterkey []byte
var confFile *cryptfs.ConfFile
if args.masterkey != "" {
// "-masterkey"
cryptfs.Info.Printf("Using explicit master key.\n")
@ -257,15 +258,12 @@ func main() {
masterkey = make([]byte, cryptfs.KEY_LEN)
} else {
// Load master key from config file
var confFile *cryptfs.ConfFile
masterkey, confFile = loadConfig(&args)
printMasterKey(masterkey)
// Settings from the config file override command line args
args.plaintextnames = confFile.IsFeatureFlagSet(cryptfs.FlagPlaintextNames)
args.diriv = confFile.IsFeatureFlagSet(cryptfs.FlagDirIV)
}
// Initialize FUSE server
srv := pathfsFrontend(masterkey, args)
cryptfs.Debug.Printf("args: %v\n", args)
srv := pathfsFrontend(masterkey, args, confFile)
cryptfs.Info.Println("Filesystem ready.")
// We are ready - send USR1 signal to our parent
if args.notifypid > 0 {
@ -279,11 +277,27 @@ func main() {
// main exits with code 0
}
// pathfsFrontend - initialize FUSE server based on go-fuse's PathFS.
// pathfsFrontend - initialize gocryptfs/pathfs_frontend
// Calls os.Exit on errors
func pathfsFrontend(key []byte, args argContainer) *fuse.Server {
func pathfsFrontend(key []byte, args argContainer, confFile *cryptfs.ConfFile) *fuse.Server {
finalFs := pathfs_frontend.NewFS(key, args.cipherdir, args.openssl, args.plaintextnames, args.diriv)
// Reconciliate CLI and config file arguments into a Args struct that is passed to the
// filesystem implementation
frontendArgs := pathfs_frontend.Args{
Cipherdir: args.cipherdir,
Masterkey: key,
OpenSSL: args.openssl,
PlaintextNames: args.plaintextnames,
DirIV: args.diriv,
}
// confFile is nil when "-zerokey" or "-masterkey" was used
if confFile != nil {
// Settings from the config file override command line args
frontendArgs.PlaintextNames = confFile.IsFeatureFlagSet(cryptfs.FlagPlaintextNames)
frontendArgs.DirIV = confFile.IsFeatureFlagSet(cryptfs.FlagDirIV)
}
finalFs := pathfs_frontend.NewFS(frontendArgs)
pathFsOpts := &pathfs.PathNodeFsOptions{ClientInodes: true}
pathFs := pathfs.NewPathNodeFs(finalFs, pathFsOpts)
fuseOpts := &nodefs.Options{

10
pathfs_frontend/args.go Normal file
View File

@ -0,0 +1,10 @@
package pathfs_frontend
// Container for arguments that are passed from main() to pathfs_frontend
type Args struct {
Masterkey []byte
Cipherdir string
OpenSSL bool
PlaintextNames bool
DirIV bool
}

48
pathfs_frontend/fs.go
View File

@ -18,9 +18,7 @@ import (
type FS struct {
*cryptfs.CryptFS
pathfs.FileSystem // loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
backingDir string // Backing directory, cipherdir
// Are per-directory filename IVs enabled?
dirIV bool
args Args // Stores configuration arguments
// dirIVLock: Lock()ed if any "gocryptfs.diriv" file is modified
// Readers must RLock() it to prevent them from seeing intermediate
// states
@ -28,23 +26,24 @@ type FS struct {
}
// Encrypted FUSE overlay filesystem
func NewFS(key []byte, backing string, useOpenssl bool, plaintextNames bool, dirIV bool) *FS {
func NewFS(args Args) *FS {
return &FS{
CryptFS: cryptfs.NewCryptFS(key, useOpenssl, plaintextNames),
FileSystem: pathfs.NewLoopbackFileSystem(backing),
dirIV: dirIV,
backingDir: backing,
CryptFS: cryptfs.NewCryptFS(args.Masterkey, args.OpenSSL, args.PlaintextNames),
FileSystem: pathfs.NewLoopbackFileSystem(args.Cipherdir),
args: args,
}
}
// GetBackingPath - get the absolute encrypted path of the backing file
// from the relative plaintext path "relPath"
func (fs *FS) getBackingPath(relPath string) (string, error) {
encrypted, err := fs.encryptPath(relPath)
cPath, err := fs.encryptPath(relPath)
if err != nil {
return "", err
}
return filepath.Join(fs.backingDir, encrypted), nil
cAbsPath := filepath.Join(fs.args.Cipherdir, cPath)
cryptfs.Debug.Printf("getBackingPath: %s + %s -> %s\n", fs.args.Cipherdir, relPath, cAbsPath)
return cAbsPath, nil
}
func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
@ -85,12 +84,12 @@ func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, f
// silently ignore "gocryptfs.conf" in the top level dir
continue
}
if fs.dirIV && cName == cryptfs.DIRIV_FILENAME {
if fs.args.DirIV && cName == cryptfs.DIRIV_FILENAME {
// silently ignore "gocryptfs.diriv" everywhere if dirIV is enabled
continue
}
var name string
if !fs.dirIV {
if !fs.args.DirIV {
name, err = fs.decryptPath(cName)
} else {
// When dirIV is enabled we need the full path to be able to decrypt it
@ -123,15 +122,16 @@ func (fs *FS) mangleOpenFlags(flags uint32) (newFlags int, writeOnly bool) {
}
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 fs.CryptFS.IsFiltered(path) {
return nil, fuse.EPERM
}
iflags, writeOnly := fs.mangleOpenFlags(flags)
cPath, err := fs.getBackingPath(path)
if err != nil {
cryptfs.Debug.Printf("Open: getBackingPath: %v\n", err)
return nil, fuse.ToStatus(err)
}
cryptfs.Debug.Printf("Open: %s\n", cPath)
f, err := os.OpenFile(cPath, iflags, 0666)
if err != nil {
return nil, fuse.ToStatus(err)
@ -214,6 +214,16 @@ func (fs *FS) Readlink(path string, context *fuse.Context) (out string, status f
if status != fuse.OK {
return "", status
}
// Old filesystem: symlinks are encrypted like paths (CBC)
if !fs.args.DirIV {
target, err := fs.decryptPath(cTarget)
if err != nil {
cryptfs.Warn.Printf("Readlink: CBC decryption failed: %v", err)
return "", fuse.EIO
}
return target, fuse.OK
}
// Since gocryptfs v0.5 symlinks are encrypted like file contents (GCM)
cBinTarget, err := base64.URLEncoding.DecodeString(cTarget)
if err != nil {
cryptfs.Warn.Printf("Readlink: %v\n", err)
@ -335,7 +345,17 @@ func (fs *FS) Symlink(target string, linkName string, context *fuse.Context) (co
if err != nil {
return fuse.ToStatus(err)
}
// Old filesystem: symlinks are encrypted like paths (CBC)
if !fs.args.DirIV {
cTarget, err := fs.encryptPath(target)
if err != nil {
cryptfs.Warn.Printf("Symlink: BUG: we should not get an error here: %v\n", err)
return fuse.ToStatus(err)
}
err = os.Symlink(cTarget, cPath)
return fuse.ToStatus(err)
}
// Since gocryptfs v0.5 symlinks are encrypted like file contents (GCM)
cBinTarget := fs.CryptFS.EncryptBlock([]byte(target), 0, nil)
cTarget := base64.URLEncoding.EncodeToString(cBinTarget)

8
pathfs_frontend/names.go
View File

@ -7,19 +7,19 @@ import (
)
func (fs *FS) encryptPath(plainPath string) (string, error) {
if !fs.dirIV {
if !fs.args.DirIV {
return fs.CryptFS.TranslatePathZeroIV(plainPath, cryptfs.OpEncrypt)
}
fs.dirIVLock.RLock()
defer fs.dirIVLock.RUnlock()
return fs.CryptFS.EncryptPathDirIV(plainPath, fs.backingDir)
return fs.CryptFS.EncryptPathDirIV(plainPath, fs.args.Cipherdir)
}
func (fs *FS) decryptPath(cipherPath string) (string, error) {
if !fs.dirIV {
if !fs.args.DirIV {
return fs.CryptFS.TranslatePathZeroIV(cipherPath, cryptfs.OpDecrypt)
}
fs.dirIVLock.RLock()
defer fs.dirIVLock.RUnlock()
return fs.CryptFS.DecryptPathDirIV(cipherPath, fs.backingDir)
return fs.CryptFS.DecryptPathDirIV(cipherPath, fs.args.Cipherdir)
}