nsfs: add ioctl to get a parent namespace
Pid and user namepaces are hierarchical. There is no way to discover
parent-child relationships.
In a future we will use this interface to dump and restore nested
namespaces.
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index c02d744..4fa2d56 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -388,6 +388,24 @@
return 0;
}
+static struct ns_common *pidns_get_parent(struct ns_common *ns)
+{
+ struct pid_namespace *active = task_active_pid_ns(current);
+ struct pid_namespace *pid_ns, *p;
+
+ /* See if the parent is in the current namespace */
+ pid_ns = p = to_pid_ns(ns)->parent;
+ for (;;) {
+ if (!p)
+ return ERR_PTR(-EPERM);
+ if (p == active)
+ break;
+ p = p->parent;
+ }
+
+ return &get_pid_ns(pid_ns)->ns;
+}
+
static struct user_namespace *pidns_owner(struct ns_common *ns)
{
return to_pid_ns(ns)->user_ns;
@@ -400,6 +418,7 @@
.put = pidns_put,
.install = pidns_install,
.owner = pidns_owner,
+ .get_parent = pidns_get_parent,
};
static __init int pid_namespaces_init(void)