hardcoresushi/libgocryptfs
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fusefrontend_reverse: move pathiv to its own package

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We will also need it in forward mode.
This commit is contained in:
Jakob Unterwurzacher 2017-05-28 18:09:02 +02:00
parent 4d2cc551cf
commit 857507e8b1
7 changed files with 38 additions and 26 deletions
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3
internal/fusefrontend_reverse/ctlsock_interface.go
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@ -6,6 +6,7 @@ import (
"syscall"
"github.com/rfjakob/gocryptfs/internal/ctlsock"
"github.com/rfjakob/gocryptfs/internal/pathiv"
)
var _ ctlsock.Interface = &ReverseFS{} // Verify that interface is implemented.
@ -20,7 +21,7 @@ func (rfs *ReverseFS) EncryptPath(plainPath string) (string, error) {
cipherPath := ""
parts := strings.Split(plainPath, "/")
for _, part := range parts {
dirIV := derivePathIV(cipherPath, ivPurposeDirIV)
dirIV := pathiv.Derive(cipherPath, pathiv.PurposeDirIV)
encryptedPart := rfs.nameTransform.EncryptName(part, dirIV)
if rfs.args.LongNames && len(encryptedPart) > syscall.NAME_MAX {
encryptedPart = rfs.nameTransform.HashLongName(encryptedPart)

3
internal/fusefrontend_reverse/reverse_longnames.go
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@ -12,6 +12,7 @@ import (
"github.com/hanwen/go-fuse/fuse/nodefs"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/pathiv"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
@ -91,7 +92,7 @@ func (rfs *ReverseFS) newNameFile(relPath string) (nodefs.File, fuse.Status) {
if err != nil {
return nil, fuse.ToStatus(err)
}
dirIV := derivePathIV(cDir, ivPurposeDirIV)
dirIV := pathiv.Derive(cDir, pathiv.PurposeDirIV)
// plain name
pName, err := rfs.findLongnameParent(pDir, dirIV, longname)
if err != nil {

5
internal/fusefrontend_reverse/rfile.go
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@ -14,6 +14,7 @@ import (
"github.com/hanwen/go-fuse/fuse/nodefs"
"github.com/rfjakob/gocryptfs/internal/contentenc"
"github.com/rfjakob/gocryptfs/internal/pathiv"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
@ -60,8 +61,8 @@ func (rfs *ReverseFS) newFile(relPath string, flags uint32) (nodefs.File, fuse.S
tlog.Debug.Printf("ino%d: newFile: found in the inode table", st.Ino)
derivedIVs = v.(derivedIVContainer)
} else {
derivedIVs.id = derivePathIV(relPath, ivPurposeFileID)
derivedIVs.block0IV = derivePathIV(relPath, ivPurposeBlock0IV)
derivedIVs.id = pathiv.Derive(relPath, pathiv.PurposeFileID)
derivedIVs.block0IV = pathiv.Derive(relPath, pathiv.PurposeBlock0IV)
// Nlink > 1 means there is more than one path to this file.
// Store the derived values so we always return the same data,
// regardless of the path that is used to access the file.

5
internal/fusefrontend_reverse/rfs.go
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@ -16,6 +16,7 @@ import (
"github.com/rfjakob/gocryptfs/internal/cryptocore"
"github.com/rfjakob/gocryptfs/internal/fusefrontend"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/pathiv"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
@ -263,7 +264,7 @@ func (rfs *ReverseFS) OpenDir(cipherPath string, context *fuse.Context) ([]fuse.
nVirtual := 1
// Encrypt names
dirIV := derivePathIV(cipherPath, ivPurposeDirIV)
dirIV := pathiv.Derive(cipherPath, pathiv.PurposeDirIV)
for i := range entries {
var cName string
// ".gocryptfs.reverse.conf" in the root directory is mapped to "gocryptfs.conf"
@ -305,7 +306,7 @@ func (rfs *ReverseFS) Readlink(cipherPath string, context *fuse.Context) (string
if rfs.args.PlaintextNames {
return plainTarget, fuse.OK
}
nonce := derivePathIV(cipherPath, ivPurposeSymlinkIV)
nonce := pathiv.Derive(cipherPath, pathiv.PurposeSymlinkIV)
// Symlinks are encrypted like file contents and base64-encoded
cBinTarget := rfs.contentEnc.EncryptBlockNonce([]byte(plainTarget), 0, nil, nonce)
cTarget := rfs.nameTransform.B64.EncodeToString(cBinTarget)

21
internal/fusefrontend_reverse/rpath.go
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@ -1,13 +1,13 @@
package fusefrontend_reverse
import (
"crypto/sha256"
"encoding/base64"
"path/filepath"
"strings"
"syscall"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/pathiv"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
@ -20,23 +20,6 @@ func saneDir(path string) string {
return d
}
type ivPurposeType string
const (
ivPurposeDirIV ivPurposeType = "DIRIV"
ivPurposeFileID ivPurposeType = "FILEID"
ivPurposeSymlinkIV ivPurposeType = "SYMLINKIV"
ivPurposeBlock0IV ivPurposeType = "BLOCK0IV"
)
// derivePathIV derives an IV from an encrypted path by hashing it with sha256
func derivePathIV(path string, purpose ivPurposeType) []byte {
// Use null byte as separator as it cannot occur in the path
extended := []byte(path + "\000" + string(purpose))
hash := sha256.Sum256(extended)
return hash[:nametransform.DirIVLen]
}
// abs basically returns storage dir + "/" + relPath.
// It takes an error parameter so it can directly wrap decryptPath like this:
// a, err := rfs.abs(rfs.decryptPath(relPath))
@ -104,7 +87,7 @@ func (rfs *ReverseFS) decryptPath(relPath string) (string, error) {
// Start at the top and recurse
currentCipherDir := filepath.Join(parts[:i]...)
currentPlainDir := filepath.Join(transformedParts[:i]...)
dirIV = derivePathIV(currentCipherDir, ivPurposeDirIV)
dirIV = pathiv.Derive(currentCipherDir, pathiv.PurposeDirIV)
transformedPart, err := rfs.rDecryptName(parts[i], dirIV, currentPlainDir)
if err != nil {
return "", err

3
internal/fusefrontend_reverse/virtualfile.go
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@ -6,6 +6,7 @@ import (
"github.com/hanwen/go-fuse/fuse"
"github.com/hanwen/go-fuse/fuse/nodefs"
"github.com/rfjakob/gocryptfs/internal/pathiv"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
@ -27,7 +28,7 @@ func (rfs *ReverseFS) newDirIVFile(cRelPath string) (nodefs.File, fuse.Status) {
if err != nil {
return nil, fuse.ToStatus(err)
}
return rfs.newVirtualFile(derivePathIV(cDir, ivPurposeDirIV), absDir)
return rfs.newVirtualFile(pathiv.Derive(cDir, pathiv.PurposeDirIV), absDir)
}
type virtualFile struct {

24
internal/pathiv/pathiv.go Normal file
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@ -0,0 +1,24 @@
package pathiv
import (
"crypto/sha256"
"github.com/rfjakob/gocryptfs/internal/nametransform"
)
type Purpose string
const (
PurposeDirIV Purpose = "DIRIV"
PurposeFileID Purpose = "FILEID"
PurposeSymlinkIV Purpose = "SYMLINKIV"
PurposeBlock0IV Purpose = "BLOCK0IV"
)
// Derive derives an IV from an encrypted path by hashing it with sha256
func Derive(path string, purpose Purpose) []byte {
// Use null byte as separator as it cannot occur in the path
extended := []byte(path + "\000" + string(purpose))
hash := sha256.Sum256(extended)
return hash[:nametransform.DirIVLen]
}