sysctl: Pass useful parameters to sysctl permissions

- Current is implicitly avaiable so passing current->nsproxy isn't useful.
- The ctl_table_header is needed to find how the sysctl table is connected
  to the rest of sysctl.
- ctl_table_root is avaiable in the ctl_table_header so no need to it.

With these changes it becomes possible to write a version of
net_sysctl_permission that takes into account the network namespace of
the sysctl table, an important feature in extending the user namespace.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index e3a6e37..e98f393 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -38,8 +38,7 @@
 }
 
 /* Return standard mode bits for table entry. */
-static int net_ctl_permissions(struct ctl_table_root *root,
-			       struct nsproxy *nsproxy,
+static int net_ctl_permissions(struct ctl_table_header *head,
 			       struct ctl_table *table)
 {
 	/* Allow network administrator to have same access as root. */