517 lines
14 KiB
Go
517 lines
14 KiB
Go
package fusefrontend
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import (
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"context"
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"os"
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"path/filepath"
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"syscall"
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"golang.org/x/sys/unix"
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"github.com/hanwen/go-fuse/v2/fs"
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"github.com/hanwen/go-fuse/v2/fuse"
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"github.com/rfjakob/gocryptfs/internal/nametransform"
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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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// Node is a file or directory in the filesystem tree
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// in a gocryptfs mount.
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type Node struct {
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fs.Inode
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}
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// path returns the relative plaintext path of this node
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func (n *Node) path() string {
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return n.Path(n.Root())
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}
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// rootNode returns the Root Node of the filesystem.
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func (n *Node) rootNode() *RootNode {
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return n.Root().Operations().(*RootNode)
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}
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// prepareAtSyscall returns a (dirfd, cName) pair that can be used
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// with the "___at" family of system calls (openat, fstatat, unlinkat...) to
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// access the backing encrypted directory.
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//
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// If you pass a `child` file name, the (dirfd, cName) pair will refer to
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// a child of this node.
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// If `child` is empty, the (dirfd, cName) pair refers to this node itself.
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func (n *Node) prepareAtSyscall(child string) (dirfd int, cName string, errno syscall.Errno) {
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p := n.path()
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if child != "" {
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p = filepath.Join(p, child)
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}
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rn := n.rootNode()
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if rn.isFiltered(p) {
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errno = syscall.EPERM
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return
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}
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dirfd, cName, err := rn.openBackingDir(p)
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if err != nil {
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errno = fs.ToErrno(err)
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}
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return
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}
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// Lookup - FUSE call for discovering a file.
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func (n *Node) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (ch *fs.Inode, errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall(name)
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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// Get device number and inode number into `st`
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st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
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if err != nil {
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return nil, fs.ToErrno(err)
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}
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// Get unique inode number
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n.rootNode().inoMap.TranslateStat(st)
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out.Attr.FromStat(st)
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// Create child node
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id := fs.StableAttr{
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Mode: uint32(st.Mode),
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Gen: 1,
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Ino: st.Ino,
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}
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node := &Node{}
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ch = n.NewInode(ctx, node, id)
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return ch, 0
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}
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// GetAttr - FUSE call for stat()ing a file.
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//
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// GetAttr is symlink-safe through use of openBackingDir() and Fstatat().
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func (n *Node) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut) (errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall("")
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
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if err != nil {
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return fs.ToErrno(err)
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}
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n.rootNode().inoMap.TranslateStat(st)
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out.Attr.FromStat(st)
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return 0
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}
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// newChild attaches a new child inode to n.
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// The passed-in `st` will be modified to get a unique inode number.
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func (n *Node) newChild(ctx context.Context, st *syscall.Stat_t, out *fuse.EntryOut) *fs.Inode {
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// Get unique inode number
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rn := n.rootNode()
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rn.inoMap.TranslateStat(st)
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out.Attr.FromStat(st)
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// Create child node
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id := fs.StableAttr{
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Mode: uint32(st.Mode),
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Gen: 1,
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Ino: st.Ino,
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}
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node := &Node{}
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return n.NewInode(ctx, node, id)
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}
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// Create - FUSE call. Creates a new file.
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//
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// Symlink-safe through the use of Openat().
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func (n *Node) Create(ctx context.Context, name string, flags uint32, mode uint32, out *fuse.EntryOut) (inode *fs.Inode, fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall(name)
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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var err error
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fd := -1
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// Make sure context is nil if we don't want to preserve the owner
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rn := n.rootNode()
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if !rn.args.PreserveOwner {
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ctx = nil
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}
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newFlags := rn.mangleOpenFlags(flags)
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// Handle long file name
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ctx2 := toFuseCtx(ctx)
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if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
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// Create ".name"
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err = rn.nameTransform.WriteLongNameAt(dirfd, cName, name)
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if err != nil {
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return nil, nil, 0, fs.ToErrno(err)
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}
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// Create content
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fd, err = syscallcompat.OpenatUser(dirfd, cName, newFlags|syscall.O_CREAT|syscall.O_EXCL, mode, ctx2)
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if err != nil {
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nametransform.DeleteLongNameAt(dirfd, cName)
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}
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} else {
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// Create content, normal (short) file name
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fd, err = syscallcompat.OpenatUser(dirfd, cName, newFlags|syscall.O_CREAT|syscall.O_EXCL, mode, ctx2)
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}
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if err != nil {
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// xfstests generic/488 triggers this
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if 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("Create %q: too many open files. Current \"ulimit -n\": %d", cName, lim.Cur)
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}
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return nil, nil, 0, fs.ToErrno(err)
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}
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// Get device number and inode number into `st`
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var st syscall.Stat_t
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err = syscall.Fstat(fd, &st)
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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ch := n.newChild(ctx, &st, out)
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f := os.NewFile(uintptr(fd), cName)
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return ch, NewFile2(f, rn, &st), 0, 0
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}
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// Unlink - FUSE call. Delete a file.
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//
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// Symlink-safe through use of Unlinkat().
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func (n *Node) Unlink(ctx context.Context, name string) (errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall(name)
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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// Delete content
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err := syscallcompat.Unlinkat(dirfd, cName, 0)
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if err != nil {
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return fs.ToErrno(err)
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}
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// Delete ".name" file
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if !n.rootNode().args.PlaintextNames && nametransform.IsLongContent(cName) {
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err = nametransform.DeleteLongNameAt(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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}
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return fs.ToErrno(err)
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}
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// Readlink - FUSE call.
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//
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// Symlink-safe through openBackingDir() + Readlinkat().
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func (n *Node) Readlink(ctx context.Context) (out []byte, errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall("")
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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cTarget, err := syscallcompat.Readlinkat(dirfd, cName)
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if err != nil {
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return nil, fs.ToErrno(err)
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}
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rn := n.rootNode()
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if rn.args.PlaintextNames {
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return []byte(cTarget), 0
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}
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// Symlinks are encrypted like file contents (GCM) and base64-encoded
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target, err := rn.decryptSymlinkTarget(cTarget)
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if err != nil {
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tlog.Warn.Printf("Readlink %q: decrypting target failed: %v", cName, err)
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return nil, syscall.EIO
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}
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return []byte(target), 0
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}
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// Open - FUSE call. Open already-existing file.
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//
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// Symlink-safe through Openat().
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func (n *Node) Open(ctx context.Context, flags uint32) (fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall("")
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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rn := n.rootNode()
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newFlags := rn.mangleOpenFlags(flags)
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// Taking this lock makes sure we don't race openWriteOnlyFile()
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rn.openWriteOnlyLock.RLock()
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defer rn.openWriteOnlyLock.RUnlock()
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// Open backing file
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fd, err := syscallcompat.Openat(dirfd, cName, newFlags, 0)
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// Handle a few specific errors
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if err != nil {
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if 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", cName, lim.Cur)
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}
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if err == syscall.EACCES && (int(flags)&syscall.O_ACCMODE) == syscall.O_WRONLY {
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fd, err = rn.openWriteOnlyFile(dirfd, cName, newFlags)
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}
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}
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// Could not handle the error? Bail out
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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var st syscall.Stat_t
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err = syscall.Fstat(fd, &st)
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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f := os.NewFile(uintptr(fd), cName)
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fh = NewFile2(f, rn, &st)
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return
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}
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// Setattr - FUSE call. Called for chmod, truncate, utimens, ...
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func (n *Node) Setattr(ctx context.Context, f fs.FileHandle, in *fuse.SetAttrIn, out *fuse.AttrOut) (errno syscall.Errno) {
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var f2 *File2
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if f != nil {
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f2 = f.(*File2)
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} else {
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f, _, errno := n.Open(ctx, syscall.O_RDWR)
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if errno != 0 {
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return errno
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}
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f2 = f.(*File2)
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defer f2.Release(ctx)
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}
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return f2.Setattr(ctx, in, out)
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}
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// StatFs - FUSE call. Returns information about the filesystem.
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//
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// Symlink-safe because the path is ignored.
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func (n *Node) Statfs(ctx context.Context, out *fuse.StatfsOut) syscall.Errno {
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p := n.rootNode().args.Cipherdir
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var st syscall.Statfs_t
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err := syscall.Statfs(p, &st)
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if err != nil {
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return fs.ToErrno(err)
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}
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out.FromStatfsT(&st)
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return 0
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}
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// Mknod - FUSE call. Create a device file.
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//
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// Symlink-safe through use of Mknodat().
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func (n *Node) Mknod(ctx context.Context, name string, mode, rdev uint32, out *fuse.EntryOut) (inode *fs.Inode, errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall("")
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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// Make sure context is nil if we don't want to preserve the owner
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rn := n.rootNode()
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if !rn.args.PreserveOwner {
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ctx = nil
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}
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// Create ".name" file to store long file name (except in PlaintextNames mode)
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var err error
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ctx2 := toFuseCtx(ctx)
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if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
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err := rn.nameTransform.WriteLongNameAt(dirfd, cName, name)
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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// Create "gocryptfs.longfile." device node
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err = syscallcompat.MknodatUser(dirfd, cName, mode, int(rdev), ctx2)
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if err != nil {
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nametransform.DeleteLongNameAt(dirfd, cName)
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}
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} else {
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// Create regular device node
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err = syscallcompat.MknodatUser(dirfd, cName, mode, int(rdev), ctx2)
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}
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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inode = n.newChild(ctx, st, out)
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return inode, 0
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}
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// Link - FUSE call. Creates a hard link at "newPath" pointing to file
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// "oldPath".
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//
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// Symlink-safe through use of Linkat().
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func (n *Node) Link(ctx context.Context, target fs.InodeEmbedder, name string, out *fuse.EntryOut) (inode *fs.Inode, errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall(name)
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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n2 := toNode(target)
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dirfd2, cName2, errno := n2.prepareAtSyscall("")
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd2)
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// Handle long file name (except in PlaintextNames mode)
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rn := n.rootNode()
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var err error
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if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
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err = rn.nameTransform.WriteLongNameAt(dirfd, cName, name)
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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// Create "gocryptfs.longfile." link
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err = syscallcompat.Linkat(dirfd2, cName2, dirfd, cName, 0)
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if err != nil {
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nametransform.DeleteLongNameAt(dirfd, cName)
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}
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} else {
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// Create regular link
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err = syscallcompat.Linkat(dirfd2, cName2, dirfd, cName, 0)
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}
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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inode = n.newChild(ctx, st, out)
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return inode, 0
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}
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// Symlink - FUSE call. Create a symlink.
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//
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// Symlink-safe through use of Symlinkat.
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func (n *Node) Symlink(ctx context.Context, target, name string, out *fuse.EntryOut) (inode *fs.Inode, errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall(name)
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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// Make sure context is nil if we don't want to preserve the owner
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rn := n.rootNode()
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if !rn.args.PreserveOwner {
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ctx = nil
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}
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cTarget := target
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if !rn.args.PlaintextNames {
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// Symlinks are encrypted like file contents (GCM) and base64-encoded
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cTarget = rn.encryptSymlinkTarget(target)
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}
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// Create ".name" file to store long file name (except in PlaintextNames mode)
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var err error
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ctx2 := toFuseCtx(ctx)
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if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
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err = rn.nameTransform.WriteLongNameAt(dirfd, cName, name)
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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// Create "gocryptfs.longfile." symlink
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err = syscallcompat.SymlinkatUser(cTarget, dirfd, cName, ctx2)
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if err != nil {
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nametransform.DeleteLongNameAt(dirfd, cName)
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}
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} else {
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// Create symlink
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err = syscallcompat.SymlinkatUser(cTarget, dirfd, cName, ctx2)
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}
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st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
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if err != nil {
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errno = fs.ToErrno(err)
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return
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}
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inode = n.newChild(ctx, st, out)
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return inode, 0
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}
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// Rename - FUSE call.
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//
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// Symlink-safe through Renameat().
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func (n *Node) Rename(ctx context.Context, name string, newParent fs.InodeEmbedder, newName string, flags uint32) (errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall(name)
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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n2 := toNode(newParent)
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dirfd2, cName2, errno := n2.prepareAtSyscall("")
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd2)
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// Easy case.
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rn := n.rootNode()
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if rn.args.PlaintextNames {
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return fs.ToErrno(unix.Renameat2(dirfd, cName, dirfd2, cName2, uint(flags)))
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}
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// Long destination file name: create .name file
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nameFileAlreadyThere := false
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var err error
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if nametransform.IsLongContent(cName2) {
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err = rn.nameTransform.WriteLongNameAt(dirfd2, cName2, newName)
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// Failure to write the .name file is expected when the target path already
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// exists. Since hashes are pretty unique, there is no need to modify the
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// .name file in this case, and we ignore the error.
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if err == syscall.EEXIST {
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nameFileAlreadyThere = true
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} else if err != nil {
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return fs.ToErrno(err)
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}
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}
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// Actual rename
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tlog.Debug.Printf("Renameat %d/%s -> %d/%s\n", dirfd, cName, dirfd2, cName2)
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err = unix.Renameat2(dirfd, cName, dirfd2, cName2, uint(flags))
|
|
if err == syscall.ENOTEMPTY || err == syscall.EEXIST {
|
|
// If an empty directory is overwritten we will always get an error as
|
|
// the "empty" directory will still contain gocryptfs.diriv.
|
|
// Interestingly, ext4 returns ENOTEMPTY while xfs returns EEXIST.
|
|
// We handle that by trying to fs.Rmdir() the target directory and trying
|
|
// again.
|
|
tlog.Debug.Printf("Rename: Handling ENOTEMPTY")
|
|
if n2.Rmdir(ctx, newName) == 0 {
|
|
err = unix.Renameat2(dirfd, cName, dirfd2, cName2, uint(flags))
|
|
}
|
|
}
|
|
if err != nil {
|
|
if nametransform.IsLongContent(cName2) && nameFileAlreadyThere == false {
|
|
// Roll back .name creation unless the .name file was already there
|
|
nametransform.DeleteLongNameAt(dirfd2, cName2)
|
|
}
|
|
return fs.ToErrno(err)
|
|
}
|
|
if nametransform.IsLongContent(cName) {
|
|
nametransform.DeleteLongNameAt(dirfd, cName)
|
|
}
|
|
return 0
|
|
}
|