netns: Deduplicate and fix copy_net_ns when !CONFIG_NET_NS

The copy of copy_net_ns used when the network stack is not
built is broken as it does not return -EINVAL when attempting
to create a new network namespace.  We don't even have
a previous network namespace.

Since we need a copy of copy_net_ns in net/net_namespace.h that is
available when the networking stack is not built at all move the
correct version of copy_net_ns from net_namespace.c into net_namespace.h
Leaving us with just 2 versions of copy_net_ns.  One version for when
we compile in network namespace suport and another stub for all other
occasions.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

2 files changed, 9 insertions, 13 deletions

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 95e646641184..32dcb6085ebe 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -126,16 +126,19 @@ struct net {
 /* Init's network namespace */
 extern struct net init_net;
 
-#ifdef CONFIG_NET
+#ifdef CONFIG_NET_NS
 extern struct net *copy_net_ns(unsigned long flags, struct net *net_ns);
 
-#else /* CONFIG_NET */
-static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
+#else /* CONFIG_NET_NS */
+#include <linux/sched.h>
+#include <linux/nsproxy.h>
+static inline struct net *copy_net_ns(unsigned long flags, struct net *old_net)
 {
-        /* There is nothing to copy so this is a noop */
-        return net_ns;
+        if (flags & CLONE_NEWNET)
+                return ERR_PTR(-EINVAL);
+        return old_net;
 }
-#endif /* CONFIG_NET */
+#endif /* CONFIG_NET_NS */
 
 
 extern struct list_head net_namespace_list;
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 42f1e1c7514f..2c1c59091685 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -347,13 +347,6 @@ struct net *get_net_ns_by_fd(int fd)
 }
 
 #else
-struct net *copy_net_ns(unsigned long flags, struct net *old_net)
-{
-        if (flags & CLONE_NEWNET)
-                return ERR_PTR(-EINVAL);
-        return old_net;
-}
-
 struct net *get_net_ns_by_fd(int fd)
 {
         return ERR_PTR(-EINVAL);