userns: add a user namespace owner of ipc ns

Changelog:
	Feb 15: Don't set new ipc->user_ns if we didn't create a new
		ipc_ns.
	Feb 23: Move extern declaration to ipc_namespace.h, and group
		fwd declarations at top.

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 51952989ad42..d3c32dcec623 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -15,6 +15,7 @@
 
 #define IPCNS_CALLBACK_PRI 0
 
+struct user_namespace;
 
 struct ipc_ids {
         int in_use;
@@ -56,6 +57,8 @@ struct ipc_namespace {
         unsigned int    mq_msg_max;      /* initialized to DFLT_MSGMAX */
         unsigned int    mq_msgsize_max;  /* initialized to DFLT_MSGSIZEMAX */
 
+        /* user_ns which owns the ipc ns */
+        struct user_namespace *user_ns;
 };
 
 extern struct ipc_namespace init_ipc_ns;