563 lines
16 KiB
Go
563 lines
16 KiB
Go
// Package fusefrontend interfaces directly with the go-fuse library.
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package fusefrontend
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// FUSE operations on paths
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import (
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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/serialize_reads"
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"github.com/rfjakob/gocryptfs/internal/syscallcompat"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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// FS implements the go-fuse virtual filesystem interface.
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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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var _ pathfs.FileSystem = &FS{} // Verify that interface is implemented.
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// NewFS returns a new encrypted FUSE overlay filesystem.
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func NewFS(args Args) *FS {
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cryptoCore := cryptocore.New(args.Masterkey, args.CryptoBackend, contentenc.DefaultIVBits, args.HKDF, args.ForceDecode)
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contentEnc := contentenc.New(cryptoCore, contentenc.DefaultBS, args.ForceDecode)
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nameTransform := nametransform.New(cryptoCore.EMECipher, args.LongNames, args.Raw64)
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if args.SerializeReads {
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serialize_reads.InitSerializer()
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}
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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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// GetAttr implements pathfs.Filesystem.
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func (fs *FS) GetAttr(name string, context *fuse.Context) (*fuse.Attr, fuse.Status) {
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tlog.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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tlog.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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if fs.args.ForceOwner != nil {
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a.Owner = *fs.args.ForceOwner
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}
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return a, status
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}
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// mangleOpenFlags is used by Create() and Open() to convert the open flags the user
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// wants to the flags we internally use to open the backing file.
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func (fs *FS) mangleOpenFlags(flags uint32) (newFlags int) {
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newFlags = int(flags)
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// Convert WRONLY to RDWR. We always need read access to do read-modify-write cycles.
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if newFlags&os.O_WRONLY > 0 {
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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
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}
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// Open implements pathfs.Filesystem.
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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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newFlags := fs.mangleOpenFlags(flags)
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cPath, err := fs.getBackingPath(path)
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if err != nil {
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tlog.Debug.Printf("Open: getBackingPath: %v", err)
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return nil, fuse.ToStatus(err)
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}
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tlog.Debug.Printf("Open: %s", cPath)
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f, err := os.OpenFile(cPath, newFlags, 0666)
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if err != nil {
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err2 := err.(*os.PathError)
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if err2.Err == syscall.EMFILE {
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var lim syscall.Rlimit
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syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim)
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tlog.Warn.Printf("Open %q: too many open files. Current \"ulimit -n\": %d", cPath, lim.Cur)
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}
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return nil, fuse.ToStatus(err)
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}
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return NewFile(f, fs)
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}
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// Create implements pathfs.Filesystem.
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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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newFlags := 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 = syscallcompat.Openat(int(dirfd.Fd()), cName, newFlags|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, newFlags|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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// Set owner
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if fs.args.PreserveOwner {
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err = fd.Chown(int(context.Owner.Uid), int(context.Owner.Gid))
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if err != nil {
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tlog.Warn.Printf("Create: fd.Chown failed: %v", err)
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}
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}
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return NewFile(fd, fs)
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}
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// Chmod implements pathfs.Filesystem.
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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.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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// os.Chmod goes through the "syscallMode" translation function that messes
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// up the suid and sgid bits. So use syscall.Chmod directly.
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err = syscall.Chmod(cPath, mode)
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return fuse.ToStatus(err)
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}
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// Chown implements pathfs.Filesystem.
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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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code = fuse.ToStatus(os.Lchown(cPath, int(uid), int(gid)))
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if !code.Ok() {
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return code
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}
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if !fs.args.PlaintextNames {
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// When filename encryption is active, every directory contains
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// a "gocryptfs.diriv" file. This file should also change the owner.
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// Instead of checking if "cPath" is a directory, we just blindly
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// execute the Lchown on "cPath/gocryptfs.diriv" and ignore errors.
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dirIVPath := filepath.Join(cPath, nametransform.DirIVFilename)
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os.Lchown(dirIVPath, int(uid), int(gid))
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}
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return fuse.OK
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}
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// Mknod implements pathfs.Filesystem.
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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.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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// Create ".name" file to store 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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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 "gocryptfs.longfile." device node
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err = syscallcompat.Mknodat(int(dirfd.Fd()), cName, 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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} else {
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// Create regular device node
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err = syscall.Mknod(cPath, mode, int(dev))
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}
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if err != nil {
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return fuse.ToStatus(err)
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}
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// Set owner
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if fs.args.PreserveOwner {
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err = os.Lchown(cPath, int(context.Owner.Uid), int(context.Owner.Gid))
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if err != nil {
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tlog.Warn.Printf("Mknod: Lchown failed: %v", err)
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}
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}
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return fuse.OK
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}
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// Truncate implements pathfs.Filesystem.
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// Support truncate(2) by opening the file and calling ftruncate(2)
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// While the glibc "truncate" wrapper seems to always use ftruncate, fsstress from
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// xfstests uses this a lot by calling "truncate64" directly.
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func (fs *FS) Truncate(path string, offset uint64, context *fuse.Context) (code fuse.Status) {
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file, code := fs.Open(path, uint32(os.O_RDWR), context)
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if code != fuse.OK {
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return code
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}
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code = file.Truncate(offset)
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file.Release()
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return code
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}
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// Utimens implements pathfs.Filesystem.
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func (fs *FS) Utimens(path string, a *time.Time, m *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, a, m, context)
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}
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// StatFs implements pathfs.Filesystem.
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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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// Readlink implements pathfs.Filesystem.
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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.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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cTarget, err := os.Readlink(cPath)
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if err != nil {
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return "", fuse.ToStatus(err)
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}
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if fs.args.PlaintextNames {
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return cTarget, fuse.OK
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}
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// Symlinks are encrypted like file contents (GCM) and base64-encoded
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cBinTarget, err := fs.nameTransform.B64.DecodeString(cTarget)
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if err != nil {
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tlog.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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tlog.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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// Unlink implements pathfs.Filesystem.
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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 = syscallcompat.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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tlog.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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// Symlink implements pathfs.Filesystem.
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func (fs *FS) Symlink(target string, linkName string, context *fuse.Context) (code fuse.Status) {
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tlog.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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if fs.args.PlaintextNames {
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err = os.Symlink(target, cPath)
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return fuse.ToStatus(err)
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}
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// Symlinks are encrypted like file contents (GCM) and base64-encoded
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cBinTarget := fs.contentEnc.EncryptBlock([]byte(target), 0, nil)
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cTarget := fs.nameTransform.B64.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" file
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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 "gocryptfs.longfile." 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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} else {
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// Create symlink
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err = os.Symlink(cTarget, cPath)
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}
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if err != nil {
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return fuse.ToStatus(err)
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}
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// Set owner
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if fs.args.PreserveOwner {
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err = os.Lchown(cPath, int(context.Owner.Uid), int(context.Owner.Gid))
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if err != nil {
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tlog.Warn.Printf("Mknod: Lchown failed: %v", err)
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}
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}
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return fuse.OK
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}
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// Rename implements pathfs.Filesystem.
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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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// Use relative path
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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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// Use relative path
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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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tlog.Debug.Printf("Renameat oldfd=%d oldpath=%s newfd=%d newpath=%s\n", finalOldDirFd, finalOldPath, finalNewDirFd, finalNewPath)
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err = syscallcompat.Renameat(finalOldDirFd, finalOldPath, finalNewDirFd, finalNewPath)
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if err == syscall.ENOTEMPTY || err == syscall.EEXIST {
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// If an empty directory is overwritten we will always get an error as
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// the "empty" directory will still contain gocryptfs.diriv.
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// Interestingly, ext4 returns ENOTEMPTY while xfs returns EEXIST.
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// We handle that by trying to fs.Rmdir() the target directory and trying
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// again.
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tlog.Debug.Printf("Rename: Handling ENOTEMPTY")
|
|
if fs.Rmdir(newPath, context) == fuse.OK {
|
|
err = syscallcompat.Renameat(finalOldDirFd, finalOldPath, finalNewDirFd, finalNewPath)
|
|
}
|
|
}
|
|
if err != nil {
|
|
if newDirFd != nil {
|
|
// Roll back .name creation
|
|
nametransform.DeleteLongName(newDirFd, cNewName)
|
|
}
|
|
return fuse.ToStatus(err)
|
|
}
|
|
if oldDirFd != nil {
|
|
nametransform.DeleteLongName(oldDirFd, cOldName)
|
|
}
|
|
return fuse.OK
|
|
}
|
|
|
|
// Link implements pathfs.Filesystem.
|
|
func (fs *FS) Link(oldPath string, newPath string, context *fuse.Context) (code fuse.Status) {
|
|
if fs.isFiltered(newPath) {
|
|
return fuse.EPERM
|
|
}
|
|
cOldPath, err := fs.getBackingPath(oldPath)
|
|
if err != nil {
|
|
return fuse.ToStatus(err)
|
|
}
|
|
cNewPath, err := fs.getBackingPath(newPath)
|
|
if err != nil {
|
|
return fuse.ToStatus(err)
|
|
}
|
|
// Handle long file name
|
|
cNewName := filepath.Base(cNewPath)
|
|
if nametransform.IsLongContent(cNewName) {
|
|
dirfd, err := os.Open(filepath.Dir(cNewPath))
|
|
if err != nil {
|
|
return fuse.ToStatus(err)
|
|
}
|
|
defer dirfd.Close()
|
|
err = fs.nameTransform.WriteLongName(dirfd, cNewName, newPath)
|
|
if err != nil {
|
|
return fuse.ToStatus(err)
|
|
}
|
|
// TODO Use syscall.Linkat once it is available in Go (it is not in Go
|
|
// 1.6).
|
|
err = syscall.Link(cOldPath, cNewPath)
|
|
if err != nil {
|
|
nametransform.DeleteLongName(dirfd, cNewName)
|
|
}
|
|
return fuse.ToStatus(err)
|
|
}
|
|
return fuse.ToStatus(os.Link(cOldPath, cNewPath))
|
|
}
|
|
|
|
// Access implements pathfs.Filesystem.
|
|
func (fs *FS) Access(path string, mode uint32, context *fuse.Context) (code fuse.Status) {
|
|
if fs.isFiltered(path) {
|
|
return fuse.EPERM
|
|
}
|
|
cPath, err := fs.getBackingPath(path)
|
|
if err != nil {
|
|
return fuse.ToStatus(err)
|
|
}
|
|
return fuse.ToStatus(syscall.Access(cPath, mode))
|
|
}
|
|
|
|
// GetXAttr implements pathfs.Filesystem.
|
|
func (fs *FS) GetXAttr(name string, attr string, context *fuse.Context) ([]byte, fuse.Status) {
|
|
return nil, fuse.ENOSYS
|
|
}
|
|
|
|
// SetXAttr implements pathfs.Filesystem.
|
|
func (fs *FS) SetXAttr(name string, attr string, data []byte, flags int, context *fuse.Context) fuse.Status {
|
|
return fuse.ENOSYS
|
|
}
|
|
|
|
// ListXAttr implements pathfs.Filesystem.
|
|
func (fs *FS) ListXAttr(name string, context *fuse.Context) ([]string, fuse.Status) {
|
|
return nil, fuse.ENOSYS
|
|
}
|
|
|
|
// RemoveXAttr implements pathfs.Filesystem.
|
|
func (fs *FS) RemoveXAttr(name string, attr string, context *fuse.Context) fuse.Status {
|
|
return fuse.ENOSYS
|
|
}
|