119 lines
3.2 KiB
Go
119 lines
3.2 KiB
Go
package fusefrontend
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import (
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"context"
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"path/filepath"
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"syscall"
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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/syscallcompat"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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// toFuseCtx tries to extract a fuse.Context from a generic context.Context.
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func toFuseCtx(ctx context.Context) (ctx2 *fuse.Context) {
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if ctx == nil {
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return nil
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}
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if caller, ok := fuse.FromContext(ctx); ok {
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ctx2 = &fuse.Context{
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Caller: *caller,
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}
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}
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return ctx2
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}
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// toNode casts a generic fs.InodeEmbedder into *Node. Also handles *RootNode
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// by return rn.Node.
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func toNode(op fs.InodeEmbedder) *Node {
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if r, ok := op.(*RootNode); ok {
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return &r.Node
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}
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return op.(*Node)
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}
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// readlink reads and decrypts a symlink. Used by Readlink, Getattr, Lookup.
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func (n *Node) readlink(dirfd int, cName string) (out []byte, errno syscall.Errno) {
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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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// translateSize translates the ciphertext size in `out` into plaintext size.
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func (n *Node) translateSize(dirfd int, cName string, out *fuse.Attr) {
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if out.IsRegular() {
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rn := n.rootNode()
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out.Size = rn.contentEnc.CipherSizeToPlainSize(out.Size)
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} else if out.IsSymlink() {
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target, _ := n.readlink(dirfd, cName)
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out.Size = uint64(len(target))
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}
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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.Inode.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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// 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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rn := n.rootNode()
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// Get stable inode number based on underlying (device,ino) pair
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// (or set to zero in case of `-sharestorage`)
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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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