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Fix race condition when registering files

libgocryptfs
Hardcore Sushi 2 months ago
parent
commit
9e98192442
Signed by: hardcoresushi
GPG Key ID: AFE384344A45E13A
  1. 85
      file.go
  2. 17
      volume.go

85
file.go

@ -38,20 +38,21 @@ func mangleOpenFlags(flags uint32) (newFlags int) {
}
func (volume *Volume) registerFileHandle(fd int, cName, path string) int {
handleID := -1
volume.handlesLock.Lock()
c := 0
for handleID == -1 {
_, ok := volume.file_handles.Load(c)
for {
_, ok := volume.fileHandles[c]
if !ok {
handleID = c
break
}
c++
}
volume.file_handles.Store(handleID, &File {
volume.fileHandles[c] = &File {
fd: os.NewFile(uintptr(fd), cName),
path: string([]byte(path[:])),
})
return handleID
}
volume.handlesLock.Unlock()
return c
}
// readFileID loads the file header from disk and extracts the file ID.
@ -102,12 +103,7 @@ func createHeader(fd *os.File) (fileID []byte, err error) {
//
// Called by Read() for normal reading,
// by Write() and Truncate() via doWrite() for Read-Modify-Write.
func (volume *Volume) doRead(handleID int, dst []byte, off uint64, length uint64) ([]byte, bool) {
value, ok := volume.file_handles.Load(handleID)
if !ok {
return nil, false
}
f := value.(*File)
func (volume *Volume) doRead(f *File, dst []byte, off uint64, length uint64) ([]byte, bool) {
fd := f.fd
// Get the file ID, either from the open file table, or from disk.
var fileID []byte
@ -183,11 +179,9 @@ func (volume *Volume) doRead(handleID int, dst []byte, off uint64, length uint64
//
// Empty writes do nothing and are allowed.
func (volume *Volume) doWrite(handleID int, data []byte, off uint64) (uint32, bool) {
value, ok := volume.file_handles.Load(handleID)
if !ok {
return 0, false
}
f := value.(*File)
volume.handlesLock.RLock()
f := volume.fileHandles[handleID]
volume.handlesLock.RUnlock()
fd := f.fd
fileWasEmpty := false
var fileID []byte
@ -216,7 +210,7 @@ func (volume *Volume) doWrite(handleID int, data []byte, off uint64) (uint32, bo
// Incomplete block -> Read-Modify-Write
if b.IsPartial() {
// Read
oldData, success := volume.doRead(handleID, nil, b.BlockPlainOff(), volume.contentEnc.PlainBS())
oldData, success := volume.doRead(f, nil, b.BlockPlainOff(), volume.contentEnc.PlainBS())
if !success {
return 0, false
}
@ -299,11 +293,9 @@ func (volume *Volume) truncateGrowFile(handleID int, oldPlainSz uint64, newPlain
// The new size is block-aligned. In this case we can do everything ourselves
// and avoid the call to doWrite.
if newPlainSz%volume.contentEnc.PlainBS() == 0 {
value, ok := volume.file_handles.Load(handleID)
if !ok {
return false
}
f := value.(*File)
volume.handlesLock.RLock()
f := volume.fileHandles[handleID]
volume.handlesLock.RUnlock()
// The file was empty, so it did not have a header. Create one.
if oldPlainSz == 0 {
id, err := createHeader(f.fd)
@ -324,11 +316,9 @@ func (volume *Volume) truncateGrowFile(handleID int, oldPlainSz uint64, newPlain
}
func (volume *Volume) truncate(handleID int, newSize uint64) bool {
value, ok := volume.file_handles.Load(handleID)
if !ok {
return false
}
f := value.(*File)
volume.handlesLock.RLock()
f := volume.fileHandles[handleID]
volume.handlesLock.RUnlock()
fileFD := int(f.fd.Fd())
var err error
// Common case first: Truncate to zero
@ -359,7 +349,7 @@ func (volume *Volume) truncate(handleID int, newSize uint64) bool {
lastBlockLen := newSize - plainOff
var data []byte
if lastBlockLen > 0 {
data, success = volume.doRead(handleID, nil, plainOff, lastBlockLen)
data, success = volume.doRead(f, nil, plainOff, lastBlockLen)
if !success {
return false
}
@ -459,16 +449,14 @@ func gcf_read_file(sessionID, handleID int, offset uint64, dst_buff []byte) uint
}
volume := value.(*Volume)
value, ok = volume.file_handles.Load(handleID)
if !ok {
return 0
}
f := value.(*File)
volume.handlesLock.RLock()
f := volume.fileHandles[handleID]
volume.handlesLock.RUnlock()
f.fdLock.RLock()
defer f.fdLock.RUnlock()
f.contentLock.RLock()
defer f.contentLock.RUnlock()
out, success := volume.doRead(handleID, dst_buff[:0], offset, uint64(length))
out, success := volume.doRead(f, dst_buff[:0], offset, uint64(length))
if !success {
return 0
} else {
@ -490,13 +478,11 @@ func gcf_write_file(sessionID, handleID int, offset uint64, data []byte) uint32
}
volume := value.(*Volume)
value, ok = volume.file_handles.Load(handleID)
if !ok {
return 0
}
f := value.(*File)
volume.handlesLock.RLock()
f := volume.fileHandles[handleID]
volume.handlesLock.RUnlock()
f.fdLock.RLock()
defer f.fdLock.RUnlock()
defer f.fdLock.RUnlock()
f.contentLock.Lock()
defer f.contentLock.Unlock()
n, _ := volume.doWrite(handleID, data, offset)
@ -510,14 +496,13 @@ func gcf_close_file(sessionID, handleID int) {
return
}
volume := value.(*Volume)
value, ok = volume.file_handles.Load(handleID)
if ok {
f := value.(*File)
f.fdLock.Lock()
f.fd.Close()
volume.file_handles.Delete(handleID)
f.fdLock.Unlock()
}
volume.handlesLock.Lock()
f := volume.fileHandles[handleID]
f.fdLock.Lock()
f.fd.Close()
delete(volume.fileHandles, handleID)
volume.handlesLock.Unlock()
f.fdLock.Unlock()
}
//export gcf_remove_file

17
volume.go

@ -44,7 +44,8 @@ type Volume struct {
cryptoCore *cryptocore.CryptoCore
contentEnc *contentenc.ContentEnc
dirCache dirCache
file_handles sync.Map
handlesLock sync.RWMutex
fileHandles map[int]*File
}
var OpenedVolumes sync.Map
@ -93,6 +94,7 @@ func registerNewVolume(rootCipherDir string, masterkey []byte, cf *configfile.Co
ivLen = 0
}
newVolume.dirCache = dirCache{ivLen: ivLen}
newVolume.fileHandles = make(map[int]*File)
//find unused volumeID
volumeID := -1
@ -130,10 +132,15 @@ func gcf_close(volumeID int) {
}
volume := value.(*Volume)
volume.cryptoCore.Wipe()
volume.file_handles.Range(func (handleID, _ interface {}) bool {
gcf_close_file(volumeID, handleID.(int))
return true
})
volume.handlesLock.RLock()
fileHandles := make([]int, 0, len(volume.fileHandles))
for i := range volume.fileHandles {
fileHandles = append(fileHandles, i)
}
volume.handlesLock.RUnlock()
for i := range fileHandles {
gcf_close_file(volumeID, i)
}
volume.dirCache.Clear()
OpenedVolumes.Delete(volumeID)
}

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