netfilter: synproxy: only register hooks when needed

[mirror_ubuntu-artful-kernel.git] / net / ipv4 / netfilter / ipt_SYNPROXY.c

diff --git a/net/ipv4/netfilter/ipt_SYNPROXY.c b/net/ipv4/netfilter/ipt_SYNPROXY.c
index 3240a2614e82bd82c674aac84ab140c91670f163..c308ee0ee0bcf7b5e96aa80df69ac6066bc0ee60 100644 (file)
--- a/net/ipv4/netfilter/ipt_SYNPROXY.c
+++ b/net/ipv4/netfilter/ipt_SYNPROXY.c
@@ -409,19 +409,56 @@ static unsigned int ipv4_synproxy_hook(void *priv,
        return NF_ACCEPT;
 }
 
+static struct nf_hook_ops ipv4_synproxy_ops[] __read_mostly = {
+       {
+               .hook           = ipv4_synproxy_hook,
+               .pf             = NFPROTO_IPV4,
+               .hooknum        = NF_INET_LOCAL_IN,
+               .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
+       },
+       {
+               .hook           = ipv4_synproxy_hook,
+               .pf             = NFPROTO_IPV4,
+               .hooknum        = NF_INET_POST_ROUTING,
+               .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
+       },
+};
+
 static int synproxy_tg4_check(const struct xt_tgchk_param *par)
 {
+       struct synproxy_net *snet = synproxy_pernet(par->net);
        const struct ipt_entry *e = par->entryinfo;
+       int err;
 
        if (e->ip.proto != IPPROTO_TCP ||
            e->ip.invflags & XT_INV_PROTO)
                return -EINVAL;
 
-       return nf_ct_netns_get(par->net, par->family);
+       err = nf_ct_netns_get(par->net, par->family);
+       if (err)
+               return err;
+
+       if (snet->hook_ref4 == 0) {
+               err = nf_register_net_hooks(par->net, ipv4_synproxy_ops,
+                                           ARRAY_SIZE(ipv4_synproxy_ops));
+               if (err) {
+                       nf_ct_netns_put(par->net, par->family);
+                       return err;
+               }
+       }
+
+       snet->hook_ref4++;
+       return err;
 }
 
 static void synproxy_tg4_destroy(const struct xt_tgdtor_param *par)
 {
+       struct synproxy_net *snet = synproxy_pernet(par->net);
+
+       snet->hook_ref4--;
+       if (snet->hook_ref4 == 0)
+               nf_unregister_net_hooks(par->net, ipv4_synproxy_ops,
+                                       ARRAY_SIZE(ipv4_synproxy_ops));
        nf_ct_netns_put(par->net, par->family);
 }
 
@@ -436,46 +473,14 @@ static struct xt_target synproxy_tg4_reg __read_mostly = {
        .me             = THIS_MODULE,
 };
 
-static struct nf_hook_ops ipv4_synproxy_ops[] __read_mostly = {
-       {
-               .hook           = ipv4_synproxy_hook,
-               .pf             = NFPROTO_IPV4,
-               .hooknum        = NF_INET_LOCAL_IN,
-               .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
-       },
-       {
-               .hook           = ipv4_synproxy_hook,
-               .pf             = NFPROTO_IPV4,
-               .hooknum        = NF_INET_POST_ROUTING,
-               .priority       = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
-       },
-};
-
 static int __init synproxy_tg4_init(void)
 {
-       int err;
-
-       err = nf_register_hooks(ipv4_synproxy_ops,
-                               ARRAY_SIZE(ipv4_synproxy_ops));
-       if (err < 0)
-               goto err1;
-
-       err = xt_register_target(&synproxy_tg4_reg);
-       if (err < 0)
-               goto err2;
-
-       return 0;
-
-err2:
-       nf_unregister_hooks(ipv4_synproxy_ops, ARRAY_SIZE(ipv4_synproxy_ops));
-err1:
-       return err;
+       return xt_register_target(&synproxy_tg4_reg);
 }
 
 static void __exit synproxy_tg4_exit(void)
 {
        xt_unregister_target(&synproxy_tg4_reg);
-       nf_unregister_hooks(ipv4_synproxy_ops, ARRAY_SIZE(ipv4_synproxy_ops));
 }
 
 module_init(synproxy_tg4_init);