[PATCH] ipcns: fix !CONFIG_IPC_NS behavior

When CONFIG_IPC_NS=n, clone(CLONE_NEWIPC) claims success, but did not actually
clone a new IPC namespace.

Fix this to return -EINVAL so the caller knows his request was denied.
Signed-off-by: NSerge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/linux/ipc.h

@@ -92,19 +92,16 @@ extern struct ipc_namespace init_ipc_ns;
 
 #ifdef CONFIG_SYSVIPC
 #define INIT_IPC_NS(ns)		.ns		= &init_ipc_ns,
+extern int copy_ipcs(unsigned long flags, struct task_struct *tsk);
 #else
 #define INIT_IPC_NS(ns)
+static inline int copy_ipcs(unsigned long flags, struct task_struct *tsk)
+{ return 0; }
 #endif
 
 #ifdef CONFIG_IPC_NS
 extern void free_ipc_ns(struct kref *kref);
-extern int copy_ipcs(unsigned long flags, struct task_struct *tsk);
 extern int unshare_ipcs(unsigned long flags, struct ipc_namespace **ns);
-#else
-static inline int copy_ipcs(unsigned long flags, struct task_struct *tsk)
-{
-	return 0;
-}
 #endif
 
 static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)

ipc/util.c

@@ -144,6 +144,13 @@ void free_ipc_ns(struct kref *kref)
 	shm_exit_ns(ns);
 	kfree(ns);
 }
+#else
+int copy_ipcs(unsigned long flags, struct task_struct *tsk)
+{
+	if (flags & CLONE_NEWIPC)
+		return -EINVAL;
+	return 0;
+}
 #endif
 
 /**