diff --git a/fs/namespace.c b/fs/namespace.c
index c2f54636ec9d..de3900dd02f6 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2369,6 +2369,18 @@ bool has_locked_children(struct mount *mnt, struct dentry *dentry)
 	return __has_locked_children(mnt, dentry);
 }
 
+/* locks: namespace_shared && pinned(mnt) || mount_locked_reader */
+static bool __has_children(struct mount *mnt, struct dentry *dentry)
+{
+	struct mount *child;
+
+	list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
+		if (is_subdir(child->mnt_mountpoint, dentry))
+			return true;
+	}
+	return false;
+}
+
 /*
  * Check that there aren't references to earlier/same mount namespaces in the
  * specified subtree.  Such references can act as pins for mount namespaces
@@ -3141,12 +3153,18 @@ static struct mnt_namespace *create_new_namespace(struct path *path,
 	struct mount *mnt;
 	unsigned int copy_flags = 0;
 	bool locked = false, recurse = flags & MOUNT_COPY_RECURSIVE;
+	bool foreign = user_ns != ns->user_ns;
 
 	if (unlikely(!d_can_lookup(path->dentry)))
 		return ERR_PTR(-ENOTDIR);
 
-	if (user_ns != ns->user_ns)
-		copy_flags |= CL_SLAVE;
+	/*
+	 * Without privileges over the mount namespace the copy is made from
+	 * nothing mounted below @path may be left out. It would reveal what
+	 * it covers. That's what unshare() gives such a caller as well.
+	 */
+	if (foreign)
+		copy_flags |= CL_SLAVE | CL_COPY_UNBINDABLE;
 
 	new_ns = alloc_mnt_ns(user_ns, false);
 	if (IS_ERR(new_ns))
@@ -3180,10 +3198,14 @@ static struct mnt_namespace *create_new_namespace(struct path *path,
 	/*
 	 * We don't emulate unshare()ing a mount namespace. We stick to
 	 * the restrictions of creating detached bind-mounts. It has a
-	 * lot saner and simpler semantics.
+	 * lot saner and simpler semantics. A caller without privileges
+	 * over the mount namespace can't leave out any child though.
 	 */
 	if (flags & MOUNT_COPY_NEW)
 		mnt = clone_mnt(real_mount(path->mnt), path->dentry, copy_flags);
+	else if (foreign && !recurse &&
+		 __has_children(real_mount(path->mnt), path->dentry))
+		mnt = ERR_PTR(-EINVAL);
 	else
 		mnt = __do_loopback(path, recurse, copy_flags);
 	scoped_guard(mount_writer) {
@@ -3200,7 +3222,7 @@ static struct mnt_namespace *create_new_namespace(struct path *path,
 		 * of the real rootfs we created.
 		 */
 		attach_mnt(mnt, new_ns_root, mp.mp);
-		if (user_ns != ns->user_ns)
+		if (foreign)
 			lock_mnt_tree(new_ns_root);
 	}