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-rw-r--r--internal/cryptocore/cryptocore.go10
-rw-r--r--internal/fusefrontend/args.go1
-rw-r--r--internal/fusefrontend/fs.go4
-rw-r--r--internal/fusefrontend_reverse/rfs.go4
-rw-r--r--mount.go12
5 files changed, 20 insertions, 11 deletions
diff --git a/internal/cryptocore/cryptocore.go b/internal/cryptocore/cryptocore.go
index 1ad928d..aafe12b 100644
--- a/internal/cryptocore/cryptocore.go
+++ b/internal/cryptocore/cryptocore.go
@@ -72,7 +72,7 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
emeCipher = eme.New(emeBlockCipher)
}
- // Initilize an AEAD cipher for file content encryption.
+ // Initialize an AEAD cipher for file content encryption.
var aeadCipher cipher.AEAD
if aeadType == BackendOpenSSL || aeadType == BackendGoGCM {
gcmKey := key
@@ -84,7 +84,13 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
if IVLen != 16 {
log.Panic("stupidgcm only supports 128-bit IVs")
}
- aeadCipher = stupidgcm.New(gcmKey, forceDecode)
+ // stupidgcm does not create a private copy of the key, so things
+ // break when initFuseFrontend() overwrites it with zeros. Create
+ // a copy here. This is unneccessary when useHKDF == true, but
+ // does no harm.
+ var stupidgcmKey []byte
+ stupidgcmKey = append(stupidgcmKey, gcmKey...)
+ aeadCipher = stupidgcm.New(stupidgcmKey, forceDecode)
case BackendGoGCM:
goGcmBlockCipher, err := aes.NewCipher(gcmKey)
if err != nil {
diff --git a/internal/fusefrontend/args.go b/internal/fusefrontend/args.go
index 37f4463..fc9de73 100644
--- a/internal/fusefrontend/args.go
+++ b/internal/fusefrontend/args.go
@@ -7,7 +7,6 @@ import (
// Args is a container for arguments that are passed from main() to fusefrontend
type Args struct {
- Masterkey []byte
// Cipherdir is the backing storage directory (absolute path).
// For reverse mode, Cipherdir actually contains *plaintext* files.
Cipherdir string
diff --git a/internal/fusefrontend/fs.go b/internal/fusefrontend/fs.go
index 7a23710..3c442a5 100644
--- a/internal/fusefrontend/fs.go
+++ b/internal/fusefrontend/fs.go
@@ -42,8 +42,8 @@ type FS struct {
var _ pathfs.FileSystem = &FS{} // Verify that interface is implemented.
// NewFS returns a new encrypted FUSE overlay filesystem.
-func NewFS(args Args) *FS {
- cryptoCore := cryptocore.New(args.Masterkey, args.CryptoBackend, contentenc.DefaultIVBits, args.HKDF, args.ForceDecode)
+func NewFS(masterkey []byte, args Args) *FS {
+ cryptoCore := cryptocore.New(masterkey, args.CryptoBackend, contentenc.DefaultIVBits, args.HKDF, args.ForceDecode)
contentEnc := contentenc.New(cryptoCore, contentenc.DefaultBS, args.ForceDecode)
nameTransform := nametransform.New(cryptoCore.EMECipher, args.LongNames, args.Raw64)
diff --git a/internal/fusefrontend_reverse/rfs.go b/internal/fusefrontend_reverse/rfs.go
index 76b1361..53e6d22 100644
--- a/internal/fusefrontend_reverse/rfs.go
+++ b/internal/fusefrontend_reverse/rfs.go
@@ -40,12 +40,12 @@ var _ pathfs.FileSystem = &ReverseFS{}
// NewFS returns an encrypted FUSE overlay filesystem.
// In this case (reverse mode) the backing directory is plain-text and
// ReverseFS provides an encrypted view.
-func NewFS(args fusefrontend.Args) *ReverseFS {
+func NewFS(masterkey []byte, args fusefrontend.Args) *ReverseFS {
if args.CryptoBackend != cryptocore.BackendAESSIV {
log.Panic("reverse mode must use AES-SIV, everything else is insecure")
}
initLongnameCache()
- cryptoCore := cryptocore.New(args.Masterkey, args.CryptoBackend, contentenc.DefaultIVBits, args.HKDF, false)
+ cryptoCore := cryptocore.New(masterkey, args.CryptoBackend, contentenc.DefaultIVBits, args.HKDF, false)
contentEnc := contentenc.New(cryptoCore, contentenc.DefaultBS, false)
nameTransform := nametransform.New(cryptoCore.EMECipher, args.LongNames, args.Raw64)
diff --git a/mount.go b/mount.go
index 7405ff3..89ac6d8 100644
--- a/mount.go
+++ b/mount.go
@@ -170,7 +170,7 @@ func setOpenFileLimit() {
// initFuseFrontend - initialize gocryptfs/fusefrontend
// Calls os.Exit on errors
-func initFuseFrontend(key []byte, args *argContainer, confFile *configfile.ConfFile) *fuse.Server {
+func initFuseFrontend(masterkey []byte, args *argContainer, confFile *configfile.ConfFile) *fuse.Server {
// Reconciliate CLI and config file arguments into a fusefrontend.Args struct
// that is passed to the filesystem implementation
cryptoBackend := cryptocore.BackendGoGCM
@@ -187,7 +187,6 @@ func initFuseFrontend(key []byte, args *argContainer, confFile *configfile.ConfF
}
frontendArgs := fusefrontend.Args{
Cipherdir: args.cipherdir,
- Masterkey: key,
PlaintextNames: args.plaintextnames,
LongNames: args.longnames,
CryptoBackend: cryptoBackend,
@@ -222,14 +221,19 @@ func initFuseFrontend(key []byte, args *argContainer, confFile *configfile.ConfF
var finalFs pathfs.FileSystem
var ctlSockBackend ctlsock.Interface
if args.reverse {
- fs := fusefrontend_reverse.NewFS(frontendArgs)
+ fs := fusefrontend_reverse.NewFS(masterkey, frontendArgs)
finalFs = fs
ctlSockBackend = fs
} else {
- fs := fusefrontend.NewFS(frontendArgs)
+ fs := fusefrontend.NewFS(masterkey, frontendArgs)
finalFs = fs
ctlSockBackend = fs
}
+ // fusefrontend / fusefrontend_reverse have initialized their crypto with
+ // derived keys (HKDF), we can purge the master key from memory.
+ for i := range masterkey {
+ masterkey[i] = 0
+ }
// We have opened the socket early so that we cannot fail here after
// asking the user for the password
if args._ctlsockFd != nil {