hardcoresushi/libgocryptfs
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reverse: rename types to reverseXYZ

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...to prevent confusion with the forward variants.

FS   -> reverseFS
file -> reverseFile

Also add an incomplete read implementation.
This commit is contained in:
Jakob Unterwurzacher 2016-08-30 00:23:55 +02:00
parent 5931eea387
commit 777eb8e62f
3 changed files with 119 additions and 36 deletions
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64
internal/fusefrontend_reverse/rfile.go
View File

@ -1,27 +1,79 @@
package fusefrontend_reverse
import (
"fmt"
"io"
"os"
"github.com/hanwen/go-fuse/fuse"
"github.com/hanwen/go-fuse/fuse/nodefs"
"github.com/rfjakob/gocryptfs/internal/contentenc"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
type file struct {
var zeroFileId []byte
func init() {
zeroFileId = make([]byte, 16)
}
type reverseFile struct {
// Embed nodefs.defaultFile for a ENOSYS implementation of all methods
nodefs.File
// Backing FD
fd *os.File
// Content encryption helper
contentEnc *contentenc.ContentEnc
// nodefs.defaultFile returns ENOSYS for all operations
nodefs.File
}
func NewFile(fd *os.File, contentEnc *contentenc.ContentEnc) (nodefs.File, fuse.Status) {
return &file{
return &reverseFile{
File: nodefs.NewDefaultFile(),
fd: fd,
contentEnc: contentEnc,
File: nodefs.NewDefaultFile(),
}, fuse.OK
}
// GetAttr - FUSE call
func (rf *reverseFile) GetAttr(*fuse.Attr) fuse.Status {
fmt.Printf("reverseFile.GetAttr fd=%d\n", rf.fd.Fd())
return fuse.ENOSYS
}
// Read - FUSE call
func (rf *reverseFile) Read(buf []byte, off int64) (resultData fuse.ReadResult, status fuse.Status) {
// TODO prefix file header
length := uint64(len(buf))
blocks := rf.contentEnc.ExplodeCipherRange(uint64(off), length)
// Read the backing plaintext in one go
alignedOffset, alignedLength := contentenc.JointPlaintextRange(blocks)
tlog.Warn.Printf("alignedOffset=%d, alignedLength=%d\n", alignedOffset, alignedLength)
plaintext := make([]byte, int(alignedLength))
n, err := rf.fd.ReadAt(plaintext, int64(alignedOffset))
if err != nil && err != io.EOF {
tlog.Warn.Printf("reverseFile.Read: ReadAt: %s", err.Error())
return nil, fuse.ToStatus(err)
}
// Truncate buffer down to actually read bytes
plaintext = plaintext[0:n]
// Encrypt blocks
ciphertext := rf.contentEnc.EncryptBlocks(plaintext, blocks[0].BlockNo, zeroFileId)
// Crop down to the relevant part
var out []byte
lenHave := len(ciphertext)
skip := blocks[0].Skip
endWant := int(skip + length)
if lenHave > endWant {
out = plaintext[skip:endWant]
} else if lenHave > int(skip) {
out = plaintext[skip:lenHave]
}
// else: out stays empty, file was smaller than the requested offset
return fuse.ReadResultData(out), fuse.OK
}

52
internal/fusefrontend_reverse/rfs.go
View File

@ -2,6 +2,7 @@ package fusefrontend_reverse
import (
"os"
"syscall"
"github.com/hanwen/go-fuse/fuse"
"github.com/hanwen/go-fuse/fuse/nodefs"
@ -13,9 +14,11 @@ import (
"github.com/rfjakob/gocryptfs/internal/nametransform"
)
type FS struct {
// loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
type reverseFS struct {
// Embed pathfs.defaultFileSystem for a ENOSYS implementation of all methods
pathfs.FileSystem
// pathfs.loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
loopbackfs pathfs.FileSystem
// Stores configuration arguments
args fusefrontend.Args
// Filename encryption helper
@ -25,43 +28,56 @@ type FS struct {
}
// Encrypted FUSE overlay filesystem
func NewFS(args fusefrontend.Args) *FS {
func NewFS(args fusefrontend.Args) *reverseFS {
cryptoCore := cryptocore.New(args.Masterkey, args.OpenSSL, true)
contentEnc := contentenc.New(cryptoCore, contentenc.DefaultBS)
nameTransform := nametransform.New(cryptoCore, args.LongNames)
return &FS{
FileSystem: pathfs.NewLoopbackFileSystem(args.Cipherdir),
return &reverseFS{
// pathfs.defaultFileSystem returns ENOSYS for all operations
FileSystem: pathfs.NewDefaultFileSystem(),
loopbackfs: pathfs.NewLoopbackFileSystem(args.Cipherdir),
args: args,
nameTransform: nameTransform,
contentEnc: contentEnc,
}
}
func (fs *FS) GetAttr(relPath string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
if fs.isFiltered(relPath) {
func (rfs *reverseFS) GetAttr(relPath string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
if rfs.isFiltered(relPath) {
return nil, fuse.EPERM
}
relPath, err := fs.decryptPath(relPath)
relPath, err := rfs.decryptPath(relPath)
if err != nil {
return nil, fuse.ToStatus(err)
}
a, status := fs.FileSystem.GetAttr(relPath, context)
a, status := rfs.loopbackfs.GetAttr(relPath, context)
if a == nil {
return a, status
}
// Calculate encrypted file size
if a.IsRegular() {
a.Size = fs.contentEnc.PlainSizeToCipherSize(a.Size)
a.Size = rfs.contentEnc.PlainSizeToCipherSize(a.Size)
}
return a, fuse.OK
}
func (fs *FS) Open(relPath string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
if fs.isFiltered(relPath) {
func (rfs *reverseFS) Access(relPath string, mode uint32, context *fuse.Context) fuse.Status {
if rfs.isFiltered(relPath) {
return fuse.EPERM
}
cPath, err := rfs.abs(rfs.encryptPath(relPath))
if err != nil {
return fuse.ToStatus(err)
}
return fuse.ToStatus(syscall.Access(cPath, mode))
}
func (rfs *reverseFS) Open(relPath string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
if rfs.isFiltered(relPath) {
return nil, fuse.EPERM
}
absPath, err := fs.abs(fs.decryptPath(relPath))
absPath, err := rfs.abs(rfs.decryptPath(relPath))
if err != nil {
return nil, fuse.ToStatus(err)
}
@ -69,22 +85,22 @@ func (fs *FS) Open(relPath string, flags uint32, context *fuse.Context) (fuseFil
if err != nil {
return nil, fuse.ToStatus(err)
}
return NewFile(f, fs.contentEnc)
return NewFile(f, rfs.contentEnc)
}
func (fs *FS) OpenDir(relPath string, context *fuse.Context) ([]fuse.DirEntry, fuse.Status) {
relPath, err := fs.decryptPath(relPath)
func (rfs *reverseFS) OpenDir(relPath string, context *fuse.Context) ([]fuse.DirEntry, fuse.Status) {
relPath, err := rfs.decryptPath(relPath)
if err != nil {
return nil, fuse.ToStatus(err)
}
// Read plaintext dir
entries, status := fs.FileSystem.OpenDir(relPath, context)
entries, status := rfs.loopbackfs.OpenDir(relPath, context)
if entries == nil {
return nil, status
}
// Encrypt names
for i := range entries {
entries[i].Name, err = fs.encryptPath(entries[i].Name)
entries[i].Name, err = rfs.encryptPath(entries[i].Name)
if err != nil {
return nil, fuse.ToStatus(err)
}

39
internal/fusefrontend_reverse/rpath.go
View File

@ -1,15 +1,24 @@
package fusefrontend_reverse
import (
"encoding/base64"
"fmt"
"path/filepath"
"strings"
"syscall"
)
func (fs *FS) abs(relPath string, err error) (string, error) {
var zeroDirIV []byte
func init() {
zeroDirIV = make([]byte, 16)
}
func (rfs *reverseFS) abs(relPath string, err error) (string, error) {
if err != nil {
return "", err
}
return filepath.Join(fs.args.Cipherdir, relPath), nil
return filepath.Join(rfs.args.Cipherdir, relPath), nil
}
const (
@ -17,30 +26,36 @@ const (
DECRYPT
)
func (fs *FS) encryptPath(relPath string) (string, error) {
return fs.transformPath(relPath, ENCRYPT)
func (rfs *reverseFS) encryptPath(relPath string) (string, error) {
return rfs.transformPath(relPath, ENCRYPT)
}
func (fs *FS) decryptPath(relPath string) (string, error) {
return fs.transformPath(relPath, DECRYPT)
func (rfs *reverseFS) decryptPath(relPath string) (string, error) {
return rfs.transformPath(relPath, DECRYPT)
}
func (fs *FS) transformPath(relPath string, direction int) (string, error) {
if fs.args.PlaintextNames {
func (rfs *reverseFS) transformPath(relPath string, direction int) (string, error) {
if rfs.args.PlaintextNames || relPath == "" {
return relPath, nil
}
var err error
var transformedParts []string
iv := make([]byte, 16)
parts := strings.Split(relPath, "/")
for _, part := range parts {
var transformedPart string
switch direction {
case ENCRYPT:
transformedPart = fs.nameTransform.EncryptName(part, iv)
transformedPart = rfs.nameTransform.EncryptName(part, zeroDirIV)
case DECRYPT:
transformedPart, err = fs.nameTransform.DecryptName(part, iv)
transformedPart, err = rfs.nameTransform.DecryptName(part, zeroDirIV)
if err != nil {
// We get lots of decrypt requests for names like ".Trash" that
// are invalid base64. Convert them to ENOENT so the correct
// error gets returned to the user.
if _, ok := err.(base64.CorruptInputError); ok {
fmt.Printf("converting to ENOENT\n")
return "", syscall.ENOENT
}
return "", err
}
default:
@ -51,6 +66,6 @@ func (fs *FS) transformPath(relPath string, direction int) (string, error) {
return filepath.Join(transformedParts...), nil
}
func (fs *FS) isFiltered(relPath string) bool {
func (rfs *reverseFS) isFiltered(relPath string) bool {
return false
}