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>

fs/proc/namespaces.c

@@ -22,6 +22,9 @@ static const struct proc_ns_operations *ns_entries[] = {
 #ifdef CONFIG_UTS_NS
 	&utsns_operations,
 #endif
+#ifdef CONFIG_IPC_NS
+	&ipcns_operations,
+#endif
 };
 
 static const struct file_operations ns_file_operations = {

include/linux/proc_fs.h

@@ -267,6 +267,7 @@ struct proc_ns_operations {
 };
 extern const struct proc_ns_operations netns_operations;
 extern const struct proc_ns_operations utsns_operations;
+extern const struct proc_ns_operations ipcns_operations;
 
 union proc_op {
 	int (*proc_get_link)(struct inode *, struct path *);

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 @@ void put_ipc_ns(struct ipc_namespace *ns)
 		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,
+};