package pathfs_frontend import ( "bytes" "fmt" "io" "os" "sync" "syscall" "time" "github.com/hanwen/go-fuse/fuse" "github.com/hanwen/go-fuse/fuse/nodefs" "github.com/rfjakob/gocryptfs/cryptfs" ) // File - based on loopbackFile in go-fuse/fuse/nodefs/files.go type file struct { fd *os.File // os.File is not threadsafe. Although fd themselves are // constant during the lifetime of an open file, the OS may // reuse the fd number after it is closed. When open races // with another close, they may lead to confusion as which // file gets written in the end. lock sync.Mutex // Was the file opened O_WRONLY? writeOnly bool // Parent CryptFS cfs *cryptfs.CryptFS // Inode number ino uint64 } func NewFile(fd *os.File, writeOnly bool, cfs *cryptfs.CryptFS) nodefs.File { var st syscall.Stat_t syscall.Fstat(int(fd.Fd()), &st) return &file{ fd: fd, writeOnly: writeOnly, cfs: cfs, ino: st.Ino, } } func (f *file) InnerFile() nodefs.File { return nil } func (f *file) SetInode(n *nodefs.Inode) { } func (f *file) String() string { return fmt.Sprintf("cryptFile(%s)", f.fd.Name()) } // doRead - returns "length" plaintext bytes from plaintext offset "off". // Arguments "length" and "off" do not have to be aligned. // // doRead reads the corresponding ciphertext blocks from disk, decryptfs them and // returns the requested part of the plaintext. // // Called by Read() and by Write() and Truncate() for RMW func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) { // Read the backing ciphertext in one go alignedOffset, alignedLength, skip := f.cfs.CiphertextRange(off, length) cryptfs.Debug.Printf("CiphertextRange(%d, %d) -> %d, %d, %d\n", off, length, alignedOffset, alignedLength, skip) ciphertext := make([]byte, int(alignedLength)) f.lock.Lock() n, err := f.fd.ReadAt(ciphertext, int64(alignedOffset)) f.lock.Unlock() if err != nil && err != io.EOF { cryptfs.Warn.Printf("read: ReadAt: %s\n", err.Error()) return nil, fuse.ToStatus(err) } // Truncate ciphertext buffer down to actually read bytes ciphertext = ciphertext[0:n] blockNo := alignedOffset / f.cfs.CipherBS() cryptfs.Debug.Printf("ReadAt offset=%d bytes (%d blocks), want=%d, got=%d\n", alignedOffset, blockNo, alignedLength, n) // Decrypt it plaintext, err := f.cfs.DecryptBlocks(ciphertext, blockNo) if err != nil { blockNo := (alignedOffset + uint64(len(plaintext))) / f.cfs.PlainBS() cipherOff := blockNo * f.cfs.CipherBS() plainOff := blockNo * f.cfs.PlainBS() cryptfs.Warn.Printf("ino%d: doRead: corrupt block #%d (plainOff=%d/%d, cipherOff=%d/%d)\n", f.ino, blockNo, plainOff, f.cfs.PlainBS(), cipherOff, f.cfs.CipherBS()) return nil, fuse.EIO } // Crop down to the relevant part var out []byte lenHave := len(plaintext) lenWant := skip + int(length) if lenHave > lenWant { out = plaintext[skip : skip+int(length)] } else if lenHave > skip { out = plaintext[skip:lenHave] } else { // Out stays empty, file was smaller than the requested offset } return out, fuse.OK } // Read - FUSE call func (f *file) Read(buf []byte, off int64) (resultData fuse.ReadResult, code fuse.Status) { cryptfs.Debug.Printf("ino%d: FUSE Read: offset=%d length=%d\n", f.ino, len(buf), off) if f.writeOnly { cryptfs.Warn.Printf("ino%d: Tried to read from write-only file\n", f.ino) return nil, fuse.EBADF } out, status := f.doRead(uint64(off), uint64(len(buf))) if status == fuse.EIO { cryptfs.Warn.Printf("ino%d: Read failed with EIO, offset=%d, length=%d\n", f.ino, len(buf), off) } if status != fuse.OK { return nil, status } cryptfs.Debug.Printf("ino%d: Read: status %v, returning %d bytes\n", f.ino, status, len(out)) return fuse.ReadResultData(out), status } // Do the actual write func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) { var written uint32 status := fuse.OK dataBuf := bytes.NewBuffer(data) blocks := f.cfs.SplitRange(uint64(off), uint64(len(data))) for _, b := range blocks { blockData := dataBuf.Next(int(b.Length)) // Incomplete block -> Read-Modify-Write if b.IsPartial() { // Read o, _ := b.PlaintextRange() oldData, status := f.doRead(o, f.cfs.PlainBS()) if status != fuse.OK { cryptfs.Warn.Printf("RMW read failed: %s\n", status.String()) return written, status } // Modify blockData = f.cfs.MergeBlocks(oldData, blockData, int(b.Skip)) cryptfs.Debug.Printf("len(oldData)=%d len(blockData)=%d\n", len(oldData), len(blockData)) } // Write blockOffset, _ := b.CiphertextRange() blockData = f.cfs.EncryptBlock(blockData, b.BlockNo) cryptfs.Debug.Printf("ino%d: Writing %d bytes to block #%d, md5=%s\n", f.ino, len(blockData), b.BlockNo, cryptfs.Debug.Md5sum(blockData)) if len(blockData) != int(f.cfs.CipherBS()) { cryptfs.Debug.Printf("ino%d: Writing partial block #%d (%d bytes)\n", f.ino, b.BlockNo, len(blockData)) } f.lock.Lock() _, err := f.fd.WriteAt(blockData, int64(blockOffset)) f.lock.Unlock() if err != nil { cryptfs.Warn.Printf("Write failed: %s\n", err.Error()) status = fuse.ToStatus(err) break } written += uint32(b.Length) } return written, status } // Write - FUSE call func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) { cryptfs.Debug.Printf("ino%d: FUSE Write: offset=%d length=%d\n", f.ino, off, len(data)) fi, err := f.fd.Stat() if err != nil { cryptfs.Warn.Printf("Write: Fstat failed: %v\n", err) return 0, fuse.ToStatus(err) } plainSize := f.cfs.PlainSize(uint64(fi.Size())) if f.createsHole(plainSize, off) { status := f.zeroPad(plainSize) if status != fuse.OK { cryptfs.Warn.Printf("zeroPad returned error %v\n", status) return 0, status } } return f.doWrite(data, off) } // Release - FUSE call, forget file func (f *file) Release() { f.lock.Lock() f.fd.Close() f.lock.Unlock() } // Flush - FUSE call func (f *file) Flush() fuse.Status { f.lock.Lock() // Since Flush() may be called for each dup'd fd, we don't // want to really close the file, we just want to flush. This // is achieved by closing a dup'd fd. newFd, err := syscall.Dup(int(f.fd.Fd())) f.lock.Unlock() if err != nil { return fuse.ToStatus(err) } err = syscall.Close(newFd) return fuse.ToStatus(err) } func (f *file) Fsync(flags int) (code fuse.Status) { f.lock.Lock() r := fuse.ToStatus(syscall.Fsync(int(f.fd.Fd()))) f.lock.Unlock() return r } func (f *file) Truncate(newSize uint64) fuse.Status { // We need the old file size to determine if we are growing or shrinking // the file fi, err := f.fd.Stat() if err != nil { cryptfs.Warn.Printf("Truncate: Fstat failed: %v\n", err) return fuse.ToStatus(err) } oldSize := f.cfs.PlainSize(uint64(fi.Size())) { oldB := float32(oldSize) / float32(f.cfs.PlainBS()) newB := float32(newSize) / float32(f.cfs.PlainBS()) cryptfs.Debug.Printf("ino%d: FUSE Truncate from %.2f to %.2f blocks (%d to %d bytes)\n", f.ino, oldB, newB, oldSize, newSize) } // File grows if newSize > oldSize { blocks := f.cfs.SplitRange(oldSize, newSize-oldSize) for _, b := range blocks { // First and last block may be partial if b.IsPartial() { off, _ := b.PlaintextRange() off += b.Skip _, status := f.doWrite(make([]byte, b.Length), int64(off)) if status != fuse.OK { return status } } else { off, length := b.CiphertextRange() f.lock.Lock() err := syscall.Ftruncate(int(f.fd.Fd()), int64(off+length)) f.lock.Unlock() if err != nil { cryptfs.Warn.Printf("grow Ftruncate returned error: %v", err) return fuse.ToStatus(err) } } } return fuse.OK } else { // File shrinks blockNo := f.cfs.BlockNoPlainOff(newSize) cipherOff := blockNo * f.cfs.CipherBS() plainOff := blockNo * f.cfs.PlainBS() lastBlockLen := newSize - plainOff var data []byte if lastBlockLen > 0 { var status fuse.Status data, status = f.doRead(plainOff, lastBlockLen) if status != fuse.OK { cryptfs.Warn.Printf("shrink doRead returned error: %v", err) return status } } f.lock.Lock() err = syscall.Ftruncate(int(f.fd.Fd()), int64(cipherOff)) f.lock.Unlock() if err != nil { cryptfs.Warn.Printf("shrink Ftruncate returned error: %v", err) return fuse.ToStatus(err) } if lastBlockLen > 0 { _, status := f.doWrite(data, int64(plainOff)) return status } return fuse.OK } } func (f *file) Chmod(mode uint32) fuse.Status { f.lock.Lock() r := fuse.ToStatus(f.fd.Chmod(os.FileMode(mode))) f.lock.Unlock() return r } func (f *file) Chown(uid uint32, gid uint32) fuse.Status { f.lock.Lock() r := fuse.ToStatus(f.fd.Chown(int(uid), int(gid))) f.lock.Unlock() return r } func (f *file) GetAttr(a *fuse.Attr) fuse.Status { cryptfs.Debug.Printf("file.GetAttr()\n") st := syscall.Stat_t{} f.lock.Lock() err := syscall.Fstat(int(f.fd.Fd()), &st) f.lock.Unlock() if err != nil { return fuse.ToStatus(err) } a.FromStat(&st) a.Size = f.cfs.PlainSize(a.Size) return fuse.OK } // Allocate FUSE call, fallocate(2) func (f *file) Allocate(off uint64, sz uint64, mode uint32) fuse.Status { cryptfs.Warn.Printf("Fallocate is not supported, returning ENOSYS - see https://github.com/rfjakob/gocryptfs/issues/1\n") return fuse.ENOSYS } const _UTIME_NOW = ((1 << 30) - 1) const _UTIME_OMIT = ((1 << 30) - 2) func (f *file) Utimens(a *time.Time, m *time.Time) fuse.Status { ts := make([]syscall.Timespec, 2) if a == nil { ts[0].Nsec = _UTIME_OMIT } else { ts[0].Sec = a.Unix() } if m == nil { ts[1].Nsec = _UTIME_OMIT } else { ts[1].Sec = m.Unix() } f.lock.Lock() fn := fmt.Sprintf("/proc/self/fd/%d", f.fd.Fd()) err := syscall.UtimesNano(fn, ts) f.lock.Unlock() return fuse.ToStatus(err) }