netfilter: core: export raw versions of add/delete hook functions

This will allow the nat core to reuse the nf_hook infrastructure
to maintain nat lookup functions.

The raw versions don't assume a particular hook location, the
functions get added/deleted from the hook blob that is passed to the
functions.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 0f6b817..5f0ebf9 100644 (file)
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -186,9 +186,31 @@ static void hooks_validate(const struct nf_hook_entries *hooks)
 #endif
 }
 
+int nf_hook_entries_insert_raw(struct nf_hook_entries __rcu **pp,
+                               const struct nf_hook_ops *reg)
+{
+       struct nf_hook_entries *new_hooks;
+       struct nf_hook_entries *p;
+
+       p = rcu_dereference_raw(*pp);
+       new_hooks = nf_hook_entries_grow(p, reg);
+       if (IS_ERR(new_hooks))
+               return PTR_ERR(new_hooks);
+
+       hooks_validate(new_hooks);
+
+       rcu_assign_pointer(*pp, new_hooks);
+
+       BUG_ON(p == new_hooks);
+       nf_hook_entries_free(p);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(nf_hook_entries_insert_raw);
+
 /*
  * __nf_hook_entries_try_shrink - try to shrink hook array
  *
+ * @old -- current hook blob at @pp
  * @pp -- location of hook blob
  *
  * Hook unregistration must always succeed, so to-be-removed hooks
@@ -201,14 +223,14 @@ static void hooks_validate(const struct nf_hook_entries *hooks)
  *
  * Returns address to free, or NULL.
  */
-static void *__nf_hook_entries_try_shrink(struct nf_hook_entries __rcu **pp)
+static void *__nf_hook_entries_try_shrink(struct nf_hook_entries *old,
+                                         struct nf_hook_entries __rcu **pp)
 {
-       struct nf_hook_entries *old, *new = NULL;
        unsigned int i, j, skip = 0, hook_entries;
+       struct nf_hook_entries *new = NULL;
        struct nf_hook_ops **orig_ops;
        struct nf_hook_ops **new_ops;
 
-       old = nf_entry_dereference(*pp);
        if (WARN_ON_ONCE(!old))
                return NULL;
 
@@ -347,11 +369,10 @@ static int __nf_register_net_hook(struct net *net, int pf,
  * This cannot fail, hook unregistration must always succeed.
  * Therefore replace the to-be-removed hook with a dummy hook.
  */
-static void nf_remove_net_hook(struct nf_hook_entries *old,
-                              const struct nf_hook_ops *unreg, int pf)
+static bool nf_remove_net_hook(struct nf_hook_entries *old,
+                              const struct nf_hook_ops *unreg)
 {
        struct nf_hook_ops **orig_ops;
-       bool found = false;
        unsigned int i;
 
        orig_ops = nf_hook_entries_get_hook_ops(old);
@@ -360,21 +381,10 @@ static void nf_remove_net_hook(struct nf_hook_entries *old,
                        continue;
                WRITE_ONCE(old->hooks[i].hook, accept_all);
                WRITE_ONCE(orig_ops[i], &dummy_ops);
-               found = true;
-               break;
+               return true;
        }
 
-       if (found) {
-#ifdef CONFIG_NETFILTER_INGRESS
-               if (pf == NFPROTO_NETDEV && unreg->hooknum == NF_NETDEV_INGRESS)
-                       net_dec_ingress_queue();
-#endif
-#ifdef HAVE_JUMP_LABEL
-               static_key_slow_dec(&nf_hooks_needed[pf][unreg->hooknum]);
-#endif
-       } else {
-               WARN_ONCE(1, "hook not found, pf %d num %d", pf, unreg->hooknum);
-       }
+       return false;
 }
 
 static void __nf_unregister_net_hook(struct net *net, int pf,
@@ -395,9 +405,19 @@ static void __nf_unregister_net_hook(struct net *net, int pf,
                return;
        }
 
-       nf_remove_net_hook(p, reg, pf);
+       if (nf_remove_net_hook(p, reg)) {
+#ifdef CONFIG_NETFILTER_INGRESS
+               if (pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
+                       net_dec_ingress_queue();
+#endif
+#ifdef HAVE_JUMP_LABEL
+               static_key_slow_dec(&nf_hooks_needed[pf][reg->hooknum]);
+#endif
+       } else {
+               WARN_ONCE(1, "hook not found, pf %d num %d", pf, reg->hooknum);
+       }
 
-       p = __nf_hook_entries_try_shrink(pp);
+       p = __nf_hook_entries_try_shrink(p, pp);
        mutex_unlock(&nf_hook_mutex);
        if (!p)
                return;
@@ -417,6 +437,19 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
 }
 EXPORT_SYMBOL(nf_unregister_net_hook);
 
+void nf_hook_entries_delete_raw(struct nf_hook_entries __rcu **pp,
+                               const struct nf_hook_ops *reg)
+{
+       struct nf_hook_entries *p;
+
+       p = rcu_dereference_raw(*pp);
+       if (nf_remove_net_hook(p, reg)) {
+               p = __nf_hook_entries_try_shrink(p, pp);
+               nf_hook_entries_free(p);
+       }
+}
+EXPORT_SYMBOL_GPL(nf_hook_entries_delete_raw);
+
 int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
 {
        int err;

diff --git a/net/netfilter/nf_internals.h b/net/netfilter/nf_internals.h
index 18f6d7a..e15779f 100644 (file)
--- a/net/netfilter/nf_internals.h
+++ b/net/netfilter/nf_internals.h
@@ -15,4 +15,9 @@ void nf_queue_nf_hook_drop(struct net *net);
 /* nf_log.c */
 int __init netfilter_log_init(void);
 
+/* core.c */
+void nf_hook_entries_delete_raw(struct nf_hook_entries __rcu **pp,
+                               const struct nf_hook_ops *reg);
+int nf_hook_entries_insert_raw(struct nf_hook_entries __rcu **pp,
+                               const struct nf_hook_ops *reg);
 #endif