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fusefrontend: make Create() symlink-safe 

Use Openat() and the openBackingDir() helper so we
never follow symlinks.
This commit is contained in:
Jakob Unterwurzacher 2018-09-22 20:31:49 +02:00
parent 63762b33af
commit 897bb8924f
1 changed files with 12 additions and 22 deletions
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34
internal/fusefrontend/fs.go
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@ -196,57 +196,47 @@ func (fs *FS) openWriteOnlyFile(dirfd int, cName string, newFlags int) (fuseFile
} }
// Create implements pathfs.Filesystem. // Create implements pathfs.Filesystem.
func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Context) (fuseFile nodefs.File, code fuse.Status) { func (fs *FS) Create(path string, flags uint32, mode uint32, context *fuse.Context) (nodefs.File, fuse.Status) {
if fs.isFiltered(path) { if fs.isFiltered(path) {
return nil, fuse.EPERM return nil, fuse.EPERM
} }
newFlags := fs.mangleOpenFlags(flags) newFlags := fs.mangleOpenFlags(flags)
cPath, err := fs.getBackingPath(path) dirfd, cName, err := fs.openBackingDir(path)
if err != nil { if err != nil {
return nil, fuse.ToStatus(err) return nil, fuse.ToStatus(err)
} }
defer syscall.Close(dirfd)
var fd *os.File fd := -1
cName := filepath.Base(cPath)
// Handle long file name // Handle long file name
if !fs.args.PlaintextNames && nametransform.IsLongContent(cName) { if !fs.args.PlaintextNames && nametransform.IsLongContent(cName) {
var dirfd int
dirfd, err = syscall.Open(filepath.Dir(cPath), syscall.O_RDONLY|syscall.O_DIRECTORY, 0)
if err != nil {
return nil, fuse.ToStatus(err)
}
defer syscall.Close(dirfd)
// Create ".name" // Create ".name"
err = fs.nameTransform.WriteLongName(dirfd, cName, path) err = fs.nameTransform.WriteLongName(dirfd, cName, path)
if err != nil { if err != nil {
return nil, fuse.ToStatus(err) return nil, fuse.ToStatus(err)
} }
// Create content // Create content
var fdRaw int fd, err = syscallcompat.Openat(dirfd, cName, newFlags|os.O_CREATE|os.O_EXCL, mode)
fdRaw, err = syscallcompat.Openat(dirfd, cName, newFlags|os.O_CREATE|os.O_EXCL, mode)
if err != nil { if err != nil {
nametransform.DeleteLongName(dirfd, cName) nametransform.DeleteLongName(dirfd, cName)
return nil, fuse.ToStatus(err) return nil, fuse.ToStatus(err)
} }
fd = os.NewFile(uintptr(fdRaw), cName)
} else { } else {
// Normal (short) file name // Create content, normal (short) file name
fd, err = os.OpenFile(cPath, newFlags|os.O_CREATE|os.O_EXCL, os.FileMode(mode)) fd, err = syscallcompat.Openat(dirfd, cName, newFlags|syscall.O_CREAT|syscall.O_EXCL, mode)
if err != nil { if err != nil {
return nil, fuse.ToStatus(err) return nil, fuse.ToStatus(err)
} }
} }
// Set owner // Set owner
if fs.args.PreserveOwner { if fs.args.PreserveOwner {
err = fd.Chown(int(context.Owner.Uid), int(context.Owner.Gid)) err = syscall.Fchown(fd, int(context.Owner.Uid), int(context.Owner.Gid))
if err != nil { if err != nil {
tlog.Warn.Printf("Create: fd.Chown failed: %v", err) tlog.Warn.Printf("Create: Fchown() failed: %v", err)
} }
} }
return NewFile(fd, fs) f := os.NewFile(uintptr(fd), cName)
return NewFile(f, fs)
} }
// Chmod implements pathfs.Filesystem. // Chmod implements pathfs.Filesystem.