diff --git a/internal/fusefrontend/node.go b/internal/fusefrontend/node.go index 2f5f3ec..aa9bd51 100644 --- a/internal/fusefrontend/node.go +++ b/internal/fusefrontend/node.go @@ -400,3 +400,52 @@ func (n *Node) Link(ctx context.Context, target fs.InodeEmbedder, name string, o inode = n.newChild(ctx, st, out) return inode, 0 } + +// Symlink - FUSE call. Create a symlink. +// +// Symlink-safe through use of Symlinkat. +func (n *Node) Symlink(ctx context.Context, target, name string, out *fuse.EntryOut) (inode *fs.Inode, errno syscall.Errno) { + dirfd, cName, errno := n.prepareAtSyscall(name) + if errno != 0 { + return + } + defer syscall.Close(dirfd) + + // Make sure context is nil if we don't want to preserve the owner + rn := n.rootNode() + if !rn.args.PreserveOwner { + ctx = nil + } + + cTarget := target + if !rn.args.PlaintextNames { + // Symlinks are encrypted like file contents (GCM) and base64-encoded + cTarget = rn.encryptSymlinkTarget(target) + } + // Create ".name" file to store long file name (except in PlaintextNames mode) + var err error + ctx2 := toFuseCtx(ctx) + if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) { + err = rn.nameTransform.WriteLongNameAt(dirfd, cName, name) + if err != nil { + errno = fs.ToErrno(err) + return + } + // Create "gocryptfs.longfile." symlink + err = syscallcompat.SymlinkatUser(cTarget, dirfd, cName, ctx2) + if err != nil { + nametransform.DeleteLongNameAt(dirfd, cName) + } + } else { + // Create symlink + err = syscallcompat.SymlinkatUser(cTarget, dirfd, cName, ctx2) + } + + st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW) + if err != nil { + errno = fs.ToErrno(err) + return + } + inode = n.newChild(ctx, st, out) + return inode, 0 +} diff --git a/internal/fusefrontend/node_api_check.go b/internal/fusefrontend/node_api_check.go index a59971f..b798332 100644 --- a/internal/fusefrontend/node_api_check.go +++ b/internal/fusefrontend/node_api_check.go @@ -19,6 +19,7 @@ var _ = (fs.NodeSetattrer)((*Node)(nil)) var _ = (fs.NodeStatfser)((*Node)(nil)) var _ = (fs.NodeMknoder)((*Node)(nil)) var _ = (fs.NodeLinker)((*Node)(nil)) +var _ = (fs.NodeSymlinker)((*Node)(nil)) /* TODO var _ = (fs.NodeGetxattrer)((*Node)(nil)) @@ -26,6 +27,5 @@ var _ = (fs.NodeSetxattrer)((*Node)(nil)) var _ = (fs.NodeRemovexattrer)((*Node)(nil)) var _ = (fs.NodeListxattrer)((*Node)(nil)) var _ = (fs.NodeCopyFileRanger)((*Node)(nil)) -var _ = (fs.NodeSymlinker)((*Node)(nil)) var _ = (fs.NodeRenamer)((*Node)(nil)) */ diff --git a/internal/fusefrontend/root_node.go b/internal/fusefrontend/root_node.go index cf23169..7ceeb06 100644 --- a/internal/fusefrontend/root_node.go +++ b/internal/fusefrontend/root_node.go @@ -245,3 +245,17 @@ func (rn *RootNode) openBackingDir(relPath string) (dirfd int, cName string, err } return dirfd, cName, nil } + +// encryptSymlinkTarget: "data" is encrypted like file contents (GCM) +// and base64-encoded. +// The empty string encrypts to the empty string. +// +// Symlink-safe because it does not do any I/O. +func (rn *RootNode) encryptSymlinkTarget(data string) (cData64 string) { + if data == "" { + return "" + } + cData := rn.contentEnc.EncryptBlock([]byte(data), 0, nil) + cData64 = rn.nameTransform.B64EncodeToString(cData) + return cData64 +}