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, 5 insertions, 0 deletions

diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index b97fc9d04ddf..ac8a56e90bf8 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -80,6 +80,11 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
                 err = PTR_ERR(new_nsp->ipc_ns);
                 goto out_ipc;
         }
+        if (new_nsp->ipc_ns != tsk->nsproxy->ipc_ns) {
+                put_user_ns(new_nsp->ipc_ns->user_ns);
+                new_nsp->ipc_ns->user_ns = task_cred_xxx(tsk, user)->user_ns;
+                get_user_ns(new_nsp->ipc_ns->user_ns);
+        }
 
         new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
         if (IS_ERR(new_nsp->pid_ns)) {