ns proc: Add support for the ipc namespace

Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/ipc/namespace.c b/ipc/namespace.c
index 8054c8e..ce0a647 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -12,6 +12,7 @@
 #include <linux/fs.h>
 #include <linux/mount.h>
 #include <linux/user_namespace.h>
+#include <linux/proc_fs.h>
 
 #include "util.h"
 
@@ -140,3 +141,39 @@
 		free_ipc_ns(ns);
 	}
 }
+
+static void *ipcns_get(struct task_struct *task)
+{
+	struct ipc_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	rcu_read_lock();
+	nsproxy = task_nsproxy(task);
+	if (nsproxy)
+		ns = get_ipc_ns(nsproxy->ipc_ns);
+	rcu_read_unlock();
+
+	return ns;
+}
+
+static void ipcns_put(void *ns)
+{
+	return put_ipc_ns(ns);
+}
+
+static int ipcns_install(struct nsproxy *nsproxy, void *ns)
+{
+	/* Ditch state from the old ipc namespace */
+	exit_sem(current);
+	put_ipc_ns(nsproxy->ipc_ns);
+	nsproxy->ipc_ns = get_ipc_ns(ns);
+	return 0;
+}
+
+const struct proc_ns_operations ipcns_operations = {
+	.name		= "ipc",
+	.type		= CLONE_NEWIPC,
+	.get		= ipcns_get,
+	.put		= ipcns_put,
+	.install	= ipcns_install,
+};