userns: Simplify the user_namespace by making userns->creator a kuid.

- Transform userns->creator from a user_struct reference to a simple
  kuid_t, kgid_t pair.

  In cap_capable this allows the check to see if we are the creator of
  a namespace to become the classic suser style euid permission check.

  This allows us to remove the need for a struct cred in the mapping
  functions and still be able to dispaly the user namespace creators
  uid and gid as 0.

- Remove the now unnecessary delayed_work in free_user_ns.

  All that is left for free_user_ns to do is to call kmem_cache_free
  and put_user_ns.  Those functions can be called in any context
  so call them directly from free_user_ns removing the need for delayed work.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index d767508db4f9..8a391bd53de2 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -9,8 +9,8 @@
 struct user_namespace {
         struct kref             kref;
         struct user_namespace   *parent;
-        struct user_struct      *creator;
-        struct work_struct      destroyer;
+        kuid_t                  owner;
+        kgid_t                  group;
 };
 
 extern struct user_namespace init_user_ns;