5da292828c
We (actually, go-fuse) used to call Chown() instead of Lchown() which meant that the operation would fail on dangling symlinks. Fix this by calling os.Lchown() ourself. Also add a test case for this.
501 lines
13 KiB
Go
501 lines
13 KiB
Go
package fusefrontend
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// FUSE operations on paths
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import (
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"encoding/base64"
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"os"
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"path/filepath"
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"sync"
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"syscall"
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"time"
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"github.com/hanwen/go-fuse/fuse"
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"github.com/hanwen/go-fuse/fuse/nodefs"
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"github.com/hanwen/go-fuse/fuse/pathfs"
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"github.com/rfjakob/gocryptfs/internal/contentenc"
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"github.com/rfjakob/gocryptfs/internal/cryptocore"
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"github.com/rfjakob/gocryptfs/internal/nametransform"
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"github.com/rfjakob/gocryptfs/internal/toggledlog"
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)
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type FS struct {
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pathfs.FileSystem // loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
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args Args // Stores configuration arguments
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// dirIVLock: Lock()ed if any "gocryptfs.diriv" file is modified
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// Readers must RLock() it to prevent them from seeing intermediate
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// states
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dirIVLock sync.RWMutex
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// Filename encryption helper
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nameTransform *nametransform.NameTransform
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// Content encryption helper
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contentEnc *contentenc.ContentEnc
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}
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// Encrypted FUSE overlay filesystem
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func NewFS(args Args) *FS {
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cryptoCore := cryptocore.New(args.Masterkey, args.OpenSSL, args.GCMIV128)
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contentEnc := contentenc.New(cryptoCore, contentenc.DefaultBS)
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nameTransform := nametransform.New(cryptoCore, args.EMENames, args.LongNames)
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return &FS{
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FileSystem: pathfs.NewLoopbackFileSystem(args.Cipherdir),
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args: args,
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nameTransform: nameTransform,
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contentEnc: contentEnc,
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}
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}
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func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
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toggledlog.Debug.Printf("FS.GetAttr('%s')", name)
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if fs.isFiltered(name) {
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return nil, fuse.EPERM
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}
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cName, err := fs.encryptPath(name)
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if err != nil {
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return nil, fuse.ToStatus(err)
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}
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a, status := fs.FileSystem.GetAttr(cName, context)
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if a == nil {
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toggledlog.Debug.Printf("FS.GetAttr failed: %s", status.String())
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return a, status
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}
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if a.IsRegular() {
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a.Size = fs.contentEnc.CipherSizeToPlainSize(a.Size)
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} else if a.IsSymlink() {
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target, _ := fs.Readlink(name, context)
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a.Size = uint64(len(target))
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}
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return a, status
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}
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// We always need read access to do read-modify-write cycles
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func (fs *FS) mangleOpenFlags(flags uint32) (newFlags int, writeOnly bool) {
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newFlags = int(flags)
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if newFlags&os.O_WRONLY > 0 {
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writeOnly = true
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newFlags = newFlags ^ os.O_WRONLY | os.O_RDWR
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}
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// We also cannot open the file in append mode, we need to seek back for RMW
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newFlags = newFlags &^ os.O_APPEND
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return newFlags, writeOnly
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}
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func (fs *FS) Open(path string, flags uint32, context *fuse.Context) (fuseFile nodefs.File, status fuse.Status) {
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if fs.isFiltered(path) {
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return nil, fuse.EPERM
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}
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iflags, writeOnly := fs.mangleOpenFlags(flags)
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cPath, err := fs.getBackingPath(path)
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if err != nil {
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toggledlog.Debug.Printf("Open: getBackingPath: %v", err)
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return nil, fuse.ToStatus(err)
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}
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toggledlog.Debug.Printf("Open: %s", cPath)
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f, err := os.OpenFile(cPath, iflags, 0666)
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if err != nil {
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return nil, fuse.ToStatus(err)
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}
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return NewFile(f, writeOnly, fs.contentEnc)
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}
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func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Context) (fuseFile nodefs.File, code fuse.Status) {
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if fs.isFiltered(path) {
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return nil, fuse.EPERM
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}
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iflags, writeOnly := fs.mangleOpenFlags(flags)
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cPath, err := fs.getBackingPath(path)
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if err != nil {
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return nil, fuse.ToStatus(err)
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}
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var fd *os.File
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cName := filepath.Base(cPath)
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// Handle long file name
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if nametransform.IsLongContent(cName) {
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var dirfd *os.File
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dirfd, err = os.Open(filepath.Dir(cPath))
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if err != nil {
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return nil, fuse.ToStatus(err)
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}
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defer dirfd.Close()
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// Create ".name"
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err = fs.nameTransform.WriteLongName(dirfd, cName, path)
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if err != nil {
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return nil, fuse.ToStatus(err)
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}
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// Create content
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var fdRaw int
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fdRaw, err = syscall.Openat(int(dirfd.Fd()), cName, iflags|os.O_CREATE, mode)
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if err != nil {
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nametransform.DeleteLongName(dirfd, cName)
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return nil, fuse.ToStatus(err)
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}
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fd = os.NewFile(uintptr(fdRaw), cName)
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} else {
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// Normal (short) file name
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fd, err = os.OpenFile(cPath, iflags|os.O_CREATE, os.FileMode(mode))
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if err != nil {
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return nil, fuse.ToStatus(err)
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}
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}
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return NewFile(fd, writeOnly, fs.contentEnc)
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}
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func (fs *FS) Chmod(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
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if fs.isFiltered(path) {
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return fuse.EPERM
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}
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cPath, err := fs.encryptPath(path)
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if err != nil {
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return fuse.ToStatus(err)
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}
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return fs.FileSystem.Chmod(cPath, mode, context)
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}
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func (fs *FS) Chown(path string, uid uint32, gid uint32, context *fuse.Context) (code fuse.Status) {
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if fs.isFiltered(path) {
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return fuse.EPERM
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}
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cPath, err := fs.getBackingPath(path)
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if err != nil {
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return fuse.ToStatus(err)
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}
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return fuse.ToStatus(os.Lchown(cPath, int(uid), int(gid)))
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}
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func (fs *FS) Mknod(path string, mode uint32, dev uint32, context *fuse.Context) (code fuse.Status) {
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if fs.isFiltered(path) {
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return fuse.EPERM
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}
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cPath, err := fs.encryptPath(path)
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if err != nil {
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return fuse.ToStatus(err)
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}
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// Handle long file name
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cName := filepath.Base(cPath)
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if nametransform.IsLongContent(cName) {
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dirfd, err := os.Open(filepath.Dir(cPath))
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if err != nil {
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return fuse.ToStatus(err)
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}
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defer dirfd.Close()
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// Create ".name"
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err = fs.nameTransform.WriteLongName(dirfd, cName, path)
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if err != nil {
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return fuse.ToStatus(err)
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}
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// Create device node
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err = syscall.Mknodat(int(dirfd.Fd()), cName, uint32(mode), int(dev))
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if err != nil {
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nametransform.DeleteLongName(dirfd, cName)
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}
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return fuse.ToStatus(err)
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}
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return fs.FileSystem.Mknod(cPath, mode, dev, context)
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}
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// Only warn once
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var truncateWarnOnce sync.Once
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func (fs *FS) Truncate(path string, offset uint64, context *fuse.Context) (code fuse.Status) {
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truncateWarnOnce.Do(func() {
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toggledlog.Warn.Printf("truncate(2) is not supported, returning ENOSYS - use ftruncate(2)")
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})
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return fuse.ENOSYS
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}
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func (fs *FS) Utimens(path string, Atime *time.Time, Mtime *time.Time, context *fuse.Context) (code fuse.Status) {
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if fs.isFiltered(path) {
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return fuse.EPERM
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}
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cPath, err := fs.encryptPath(path)
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if err != nil {
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return fuse.ToStatus(err)
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}
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return fs.FileSystem.Utimens(cPath, Atime, Mtime, context)
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}
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func (fs *FS) StatFs(path string) *fuse.StatfsOut {
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if fs.isFiltered(path) {
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return nil
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}
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cPath, err := fs.encryptPath(path)
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if err != nil {
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return nil
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}
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return fs.FileSystem.StatFs(cPath)
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}
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func (fs *FS) Readlink(path string, context *fuse.Context) (out string, status fuse.Status) {
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cPath, err := fs.encryptPath(path)
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if err != nil {
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return "", fuse.ToStatus(err)
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}
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cTarget, status := fs.FileSystem.Readlink(cPath, context)
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if status != fuse.OK {
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return "", status
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}
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// Old filesystem: symlinks are encrypted like paths (CBC)
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if !fs.args.DirIV {
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var target string
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target, err = fs.decryptPath(cTarget)
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if err != nil {
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toggledlog.Warn.Printf("Readlink: CBC decryption failed: %v", err)
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return "", fuse.EIO
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}
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return target, fuse.OK
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}
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// Since gocryptfs v0.5 symlinks are encrypted like file contents (GCM)
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cBinTarget, err := base64.URLEncoding.DecodeString(cTarget)
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if err != nil {
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toggledlog.Warn.Printf("Readlink: %v", err)
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return "", fuse.EIO
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}
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target, err := fs.contentEnc.DecryptBlock([]byte(cBinTarget), 0, nil)
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if err != nil {
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toggledlog.Warn.Printf("Readlink: %v", err)
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return "", fuse.EIO
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}
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return string(target), fuse.OK
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}
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func (fs *FS) Unlink(path string, context *fuse.Context) (code fuse.Status) {
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if fs.isFiltered(path) {
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return fuse.EPERM
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}
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cPath, err := fs.getBackingPath(path)
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if err != nil {
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return fuse.ToStatus(err)
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}
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cName := filepath.Base(cPath)
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if nametransform.IsLongContent(cName) {
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var dirfd *os.File
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dirfd, err = os.Open(filepath.Dir(cPath))
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if err != nil {
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return fuse.ToStatus(err)
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}
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defer dirfd.Close()
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// Delete content
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err = syscall.Unlinkat(int(dirfd.Fd()), cName)
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if err != nil {
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return fuse.ToStatus(err)
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}
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// Delete ".name"
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err = nametransform.DeleteLongName(dirfd, cName)
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if err != nil {
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toggledlog.Warn.Printf("Unlink: could not delete .name file: %v", err)
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}
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return fuse.ToStatus(err)
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}
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err = syscall.Unlink(cPath)
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return fuse.ToStatus(err)
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}
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func (fs *FS) Symlink(target string, linkName string, context *fuse.Context) (code fuse.Status) {
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toggledlog.Debug.Printf("Symlink(\"%s\", \"%s\")", target, linkName)
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if fs.isFiltered(linkName) {
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return fuse.EPERM
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}
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cPath, err := fs.getBackingPath(linkName)
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if err != nil {
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return fuse.ToStatus(err)
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}
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// Before v0.5, symlinks were encrypted like paths (CBC)
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// TODO drop compatibility and simplify code?
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if !fs.args.DirIV {
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var cTarget string
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cTarget, err = fs.encryptPath(target)
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if err != nil {
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toggledlog.Warn.Printf("Symlink: BUG: we should not get an error here: %v", err)
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return fuse.ToStatus(err)
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}
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err = os.Symlink(cTarget, cPath)
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return fuse.ToStatus(err)
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}
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cBinTarget := fs.contentEnc.EncryptBlock([]byte(target), 0, nil)
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cTarget := base64.URLEncoding.EncodeToString(cBinTarget)
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// Handle long file name
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cName := filepath.Base(cPath)
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if nametransform.IsLongContent(cName) {
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var dirfd *os.File
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dirfd, err = os.Open(filepath.Dir(cPath))
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if err != nil {
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return fuse.ToStatus(err)
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}
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defer dirfd.Close()
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// Create ".name"
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err = fs.nameTransform.WriteLongName(dirfd, cName, linkName)
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if err != nil {
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return fuse.ToStatus(err)
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}
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// Create symlink
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// TODO use syscall.Symlinkat once it is available in Go
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err = syscall.Symlink(cTarget, cPath)
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if err != nil {
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nametransform.DeleteLongName(dirfd, cName)
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}
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return fuse.ToStatus(err)
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}
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err = os.Symlink(cTarget, cPath)
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return fuse.ToStatus(err)
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}
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func (fs *FS) Rename(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) {
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if fs.isFiltered(newPath) {
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return fuse.EPERM
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}
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cOldPath, err := fs.getBackingPath(oldPath)
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if err != nil {
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return fuse.ToStatus(err)
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}
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cNewPath, err := fs.getBackingPath(newPath)
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if err != nil {
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return fuse.ToStatus(err)
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}
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// The Rename may cause a directory to take the place of another directory.
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// That directory may still be in the DirIV cache, clear it.
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fs.nameTransform.DirIVCache.Clear()
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// Handle long source file name
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var oldDirFd *os.File
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var finalOldDirFd int
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var finalOldPath = cOldPath
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cOldName := filepath.Base(cOldPath)
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if nametransform.IsLongContent(cOldName) {
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oldDirFd, err = os.Open(filepath.Dir(cOldPath))
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if err != nil {
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return fuse.ToStatus(err)
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}
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defer oldDirFd.Close()
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finalOldDirFd = int(oldDirFd.Fd())
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finalOldPath = cOldName
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}
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// Handle long destination file name
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var newDirFd *os.File
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var finalNewDirFd int
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var finalNewPath = cNewPath
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cNewName := filepath.Base(cNewPath)
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if nametransform.IsLongContent(cNewName) {
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newDirFd, err = os.Open(filepath.Dir(cNewPath))
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if err != nil {
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return fuse.ToStatus(err)
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}
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defer newDirFd.Close()
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finalNewDirFd = int(newDirFd.Fd())
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finalNewPath = cNewName
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// Create destination .name file
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err = fs.nameTransform.WriteLongName(newDirFd, cNewName, newPath)
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if err != nil {
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return fuse.ToStatus(err)
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}
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}
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// Actual rename
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err = syscall.Renameat(finalOldDirFd, finalOldPath, finalNewDirFd, finalNewPath)
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if err == syscall.ENOTEMPTY {
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// If an empty directory is overwritten we will always get ENOTEMPTY as
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// the "empty" directory will still contain gocryptfs.diriv.
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// Handle that case by removing the target directory and trying again.
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toggledlog.Debug.Printf("Rename: Handling ENOTEMPTY")
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if fs.Rmdir(newPath, context) == fuse.OK {
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err = syscall.Renameat(finalOldDirFd, finalOldPath, finalNewDirFd, finalNewPath)
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}
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}
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if err != nil {
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if newDirFd != nil {
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// Roll back .name creation
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nametransform.DeleteLongName(newDirFd, cNewName)
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}
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return fuse.ToStatus(err)
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}
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if oldDirFd != nil {
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nametransform.DeleteLongName(oldDirFd, cOldName)
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}
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return fuse.OK
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}
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func (fs *FS) Link(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) {
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if fs.isFiltered(newPath) {
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return fuse.EPERM
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}
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cOldPath, err := fs.getBackingPath(oldPath)
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if err != nil {
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return fuse.ToStatus(err)
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}
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cNewPath, err := fs.getBackingPath(newPath)
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if err != nil {
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return fuse.ToStatus(err)
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}
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// Handle long file name
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cNewName := filepath.Base(cNewPath)
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if nametransform.IsLongContent(cNewName) {
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dirfd, err := os.Open(filepath.Dir(cNewPath))
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if err != nil {
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return fuse.ToStatus(err)
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}
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defer dirfd.Close()
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err = fs.nameTransform.WriteLongName(dirfd, cNewName, newPath)
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if err != nil {
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return fuse.ToStatus(err)
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}
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// TODO Use syscall.Linkat once it is available in Go (it is not in Go
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// 1.6).
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err = syscall.Link(cOldPath, cNewPath)
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if err != nil {
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nametransform.DeleteLongName(dirfd, cNewName)
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return fuse.ToStatus(err)
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}
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}
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return fuse.ToStatus(os.Link(cOldPath, cNewPath))
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}
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func (fs *FS) Access(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
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if fs.isFiltered(path) {
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return fuse.EPERM
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}
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cPath, err := fs.getBackingPath(path)
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if err != nil {
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return fuse.ToStatus(err)
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}
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return fuse.ToStatus(syscall.Access(cPath, mode))
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}
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func (fs *FS) GetXAttr(name string, attr string, context *fuse.Context) ([]byte, fuse.Status) {
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return nil, fuse.ENOSYS
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}
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func (fs *FS) SetXAttr(name string, attr string, data []byte, flags int, context *fuse.Context) fuse.Status {
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return fuse.ENOSYS
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}
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func (fs *FS) ListXAttr(name string, context *fuse.Context) ([]string, fuse.Status) {
|
|
return nil, fuse.ENOSYS
|
|
}
|
|
|
|
func (fs *FS) RemoveXAttr(name string, attr string, context *fuse.Context) fuse.Status {
|
|
return fuse.ENOSYS
|
|
}
|