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Diffstat (limited to 'pathfs_frontend/file.go')
-rw-r--r--pathfs_frontend/file.go179
1 files changed, 142 insertions, 37 deletions
diff --git a/pathfs_frontend/file.go b/pathfs_frontend/file.go
index 3304267..438fe77 100644
--- a/pathfs_frontend/file.go
+++ b/pathfs_frontend/file.go
@@ -23,7 +23,7 @@ type file struct {
// 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
+ fdLock sync.Mutex
// Was the file opened O_WRONLY?
writeOnly bool
@@ -33,6 +33,9 @@ type file struct {
// Inode number
ino uint64
+
+ // File header
+ header *cryptfs.FileHeader
}
func NewFile(fd *os.File, writeOnly bool, cfs *cryptfs.CryptFS) nodefs.File {
@@ -54,26 +57,83 @@ func (f *file) InnerFile() nodefs.File {
func (f *file) SetInode(n *nodefs.Inode) {
}
+// Ensure that all modifications to the file contents are serialized and no
+// reads happen concurrently.
+//
+// This prevents several races:
+// * getFileId vs Truncate
+// * zeroPad vs Read
+// * RMW vs Write
+func (f *file) wlock() {
+}
+func (f *file) rlock() {
+}
+func (f *file) unlock() {
+}
+
+// readHeader - load the file header from disk
+//
+// Returns io.EOF if the file is empty
+func (f *file) readHeader() error {
+ buf := make([]byte, cryptfs.HEADER_LEN)
+ _, err := f.fd.ReadAt(buf, 0)
+ if err != nil {
+ return err
+ }
+ h, err := cryptfs.ParseHeader(buf)
+ if err != nil {
+ return err
+ }
+ f.header = h
+
+ return nil
+}
+
+// createHeader - create a new random header and write it to disk
+func (f *file) createHeader() error {
+ h := cryptfs.RandomHeader()
+ buf := h.Pack()
+ _, err := f.fd.WriteAt(buf, 0)
+ if err != nil {
+ return err
+ }
+ f.header = h
+
+ return nil
+}
+
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.
+// Arguments "length" and "off" do not have to be block-aligned.
//
-// doRead reads the corresponding ciphertext blocks from disk, decryptfs them and
+// doRead reads the corresponding ciphertext blocks from disk, decrypts them and
// returns the requested part of the plaintext.
//
-// Called by Read() and by Write() and Truncate() for RMW
+// Called by Read() for normal reading,
+// by Write() and Truncate() for Read-Modify-Write
func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
+ // Read file header
+ if f.header == nil {
+ err := f.readHeader()
+ if err == io.EOF {
+ return nil, fuse.OK
+ }
+ if err != nil {
+ return nil, fuse.ToStatus(err)
+ }
+ }
+
// 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()
+ f.fdLock.Lock()
n, err := f.fd.ReadAt(ciphertext, int64(alignedOffset))
- f.lock.Unlock()
+ f.fdLock.Unlock()
if err != nil && err != io.EOF {
cryptfs.Warn.Printf("read: ReadAt: %s\n", err.Error())
return nil, fuse.ToStatus(err)
@@ -81,14 +141,14 @@ func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
// Truncate ciphertext buffer down to actually read bytes
ciphertext = ciphertext[0:n]
- blockNo := alignedOffset / f.cfs.CipherBS()
+ blockNo := (alignedOffset - cryptfs.HEADER_LEN) / 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)
+ plaintext, err := f.cfs.DecryptBlocks(ciphertext, blockNo, f.header.Id)
if err != nil {
blockNo := (alignedOffset + uint64(len(plaintext))) / f.cfs.PlainBS()
- cipherOff := blockNo * f.cfs.CipherBS()
+ cipherOff := cryptfs.HEADER_LEN + 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())
@@ -103,15 +163,15 @@ func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
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
}
+ // 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 {
@@ -132,8 +192,27 @@ func (f *file) Read(buf []byte, off int64) (resultData fuse.ReadResult, code fus
return fuse.ReadResultData(out), status
}
-// Do the actual write
+// doWrite - encrypt "data" and write it to plaintext offset "off"
+//
+// Arguments do not have to be block-aligned, read-modify-write is
+// performed internally as neccessary
+//
+// Called by Write() for normal writing,
+// and by Truncate() to rewrite the last file block.
func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
+
+ // Read header from disk, create a new one if the file is empty
+ if f.header == nil {
+ err := f.readHeader()
+ if err == io.EOF {
+ err = f.createHeader()
+
+ }
+ if err != nil {
+ return 0, fuse.ToStatus(err)
+ }
+ }
+
var written uint32
status := fuse.OK
dataBuf := bytes.NewBuffer(data)
@@ -158,14 +237,16 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
// 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))
+ blockData = f.cfs.EncryptBlock(blockData, b.BlockNo, f.header.Id)
+ cryptfs.Debug.Printf("ino%d: Writing %d bytes to block #%d, md5=%s\n",
+ f.ino, len(blockData) - cryptfs.BLOCK_OVERHEAD, 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))
+ cryptfs.Debug.Printf("ino%d: Writing partial block #%d (%d bytes)\n",
+ f.ino, b.BlockNo, len(blockData) - cryptfs.BLOCK_OVERHEAD)
}
- f.lock.Lock()
+ f.fdLock.Lock()
_, err := f.fd.WriteAt(blockData, int64(blockOffset))
- f.lock.Unlock()
+ f.fdLock.Unlock()
if err != nil {
cryptfs.Warn.Printf("Write failed: %s\n", err.Error())
@@ -199,20 +280,20 @@ func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) {
// Release - FUSE call, forget file
func (f *file) Release() {
- f.lock.Lock()
+ f.fdLock.Lock()
f.fd.Close()
- f.lock.Unlock()
+ f.fdLock.Unlock()
}
// Flush - FUSE call
func (f *file) Flush() fuse.Status {
- f.lock.Lock()
+ f.fdLock.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()
+ f.fdLock.Unlock()
if err != nil {
return fuse.ToStatus(err)
@@ -222,14 +303,27 @@ func (f *file) Flush() fuse.Status {
}
func (f *file) Fsync(flags int) (code fuse.Status) {
- f.lock.Lock()
+ f.fdLock.Lock()
r := fuse.ToStatus(syscall.Fsync(int(f.fd.Fd())))
- f.lock.Unlock()
+ f.fdLock.Unlock()
return r
}
func (f *file) Truncate(newSize uint64) fuse.Status {
+ // Common case first: Truncate to zero
+ if newSize == 0 {
+ f.fdLock.Lock()
+ err := syscall.Ftruncate(int(f.fd.Fd()), 0)
+ f.fdLock.Unlock()
+ if err != nil {
+ cryptfs.Warn.Printf("Ftruncate(fd, 0) returned error: %v", err)
+ return fuse.ToStatus(err)
+ }
+ // A truncate to zero kills the file header
+ f.header = nil
+ return fuse.OK
+ }
// We need the old file size to determine if we are growing or shrinking
// the file
@@ -247,6 +341,15 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
// File grows
if newSize > oldSize {
+
+ // File was empty, create new header
+ if oldSize == 0 {
+ err := f.createHeader()
+ if err != nil {
+ return fuse.ToStatus(err)
+ }
+ }
+
blocks := f.cfs.SplitRange(oldSize, newSize-oldSize)
for _, b := range blocks {
// First and last block may be partial
@@ -259,9 +362,9 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
}
} else {
off, length := b.CiphertextRange()
- f.lock.Lock()
+ f.fdLock.Lock()
err := syscall.Ftruncate(int(f.fd.Fd()), int64(off+length))
- f.lock.Unlock()
+ f.fdLock.Unlock()
if err != nil {
cryptfs.Warn.Printf("grow Ftruncate returned error: %v", err)
return fuse.ToStatus(err)
@@ -272,7 +375,7 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
} else {
// File shrinks
blockNo := f.cfs.BlockNoPlainOff(newSize)
- cipherOff := blockNo * f.cfs.CipherBS()
+ cipherOff := cryptfs.HEADER_LEN + blockNo * f.cfs.CipherBS()
plainOff := blockNo * f.cfs.PlainBS()
lastBlockLen := newSize - plainOff
var data []byte
@@ -284,13 +387,15 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
return status
}
}
- f.lock.Lock()
+ // Truncate down to last complete block
+ f.fdLock.Lock()
err = syscall.Ftruncate(int(f.fd.Fd()), int64(cipherOff))
- f.lock.Unlock()
+ f.fdLock.Unlock()
if err != nil {
cryptfs.Warn.Printf("shrink Ftruncate returned error: %v", err)
return fuse.ToStatus(err)
}
+ // Append partial block
if lastBlockLen > 0 {
_, status := f.doWrite(data, int64(plainOff))
return status
@@ -300,17 +405,17 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
}
func (f *file) Chmod(mode uint32) fuse.Status {
- f.lock.Lock()
+ f.fdLock.Lock()
r := fuse.ToStatus(f.fd.Chmod(os.FileMode(mode)))
- f.lock.Unlock()
+ f.fdLock.Unlock()
return r
}
func (f *file) Chown(uid uint32, gid uint32) fuse.Status {
- f.lock.Lock()
+ f.fdLock.Lock()
r := fuse.ToStatus(f.fd.Chown(int(uid), int(gid)))
- f.lock.Unlock()
+ f.fdLock.Unlock()
return r
}
@@ -318,9 +423,9 @@ func (f *file) Chown(uid uint32, gid uint32) fuse.Status {
func (f *file) GetAttr(a *fuse.Attr) fuse.Status {
cryptfs.Debug.Printf("file.GetAttr()\n")
st := syscall.Stat_t{}
- f.lock.Lock()
+ f.fdLock.Lock()
err := syscall.Fstat(int(f.fd.Fd()), &st)
- f.lock.Unlock()
+ f.fdLock.Unlock()
if err != nil {
return fuse.ToStatus(err)
}
@@ -330,7 +435,7 @@ func (f *file) GetAttr(a *fuse.Attr) fuse.Status {
return fuse.OK
}
-// Allocate FUSE call, fallocate(2)
+// 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
@@ -354,9 +459,9 @@ func (f *file) Utimens(a *time.Time, m *time.Time) fuse.Status {
ts[1].Sec = m.Unix()
}
- f.lock.Lock()
+ f.fdLock.Lock()
fn := fmt.Sprintf("/proc/self/fd/%d", f.fd.Fd())
err := syscall.UtimesNano(fn, ts)
- f.lock.Unlock()
+ f.fdLock.Unlock()
return fuse.ToStatus(err)
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-03 18:44:09 +0000