netfilter: Factor out the hook list selection from nf_register_hook

- Add a new function find_nf_hook_list to select the nf_hook_list

- Fail nf_register_hook when asked for a per netdevice hook list when
  support for per netdevice hook lists is not built into the kernel.

- Move the hook list head selection outside of nf_hook_mutex as
  nothing in the selection requires the hook list, and error handling
  is simpler if a mutex is not held.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index c4c3b85..fa4d3c1 100644 (file)
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -62,27 +62,31 @@ EXPORT_SYMBOL(nf_hooks_needed);
 
 static DEFINE_MUTEX(nf_hook_mutex);
 
-int nf_register_hook(struct nf_hook_ops *reg)
+static struct list_head *find_nf_hook_list(const struct nf_hook_ops *reg)
 {
-       struct list_head *nf_hook_list;
-       struct nf_hook_ops *elem;
+       struct list_head *nf_hook_list = NULL;
 
-       mutex_lock(&nf_hook_mutex);
-       switch (reg->pf) {
-       case NFPROTO_NETDEV:
+       if (reg->pf != NFPROTO_NETDEV)
+               nf_hook_list = &nf_hooks[reg->pf][reg->hooknum];
+       else if (reg->hooknum == NF_NETDEV_INGRESS) {
 #ifdef CONFIG_NETFILTER_INGRESS
-               if (reg->hooknum == NF_NETDEV_INGRESS) {
-                       BUG_ON(reg->dev == NULL);
+               if (reg->dev)
                        nf_hook_list = &reg->dev->nf_hooks_ingress;
-                       break;
-               }
 #endif
-               /* Fall through. */
-       default:
-               nf_hook_list = &nf_hooks[reg->pf][reg->hooknum];
-               break;
        }
+       return nf_hook_list;
+}
+
+int nf_register_hook(struct nf_hook_ops *reg)
+{
+       struct list_head *nf_hook_list;
+       struct nf_hook_ops *elem;
 
+       nf_hook_list = find_nf_hook_list(reg);
+       if (!nf_hook_list)
+               return -ENOENT;
+
+       mutex_lock(&nf_hook_mutex);
        list_for_each_entry(elem, nf_hook_list, list) {
                if (reg->priority < elem->priority)
                        break;