netfilter: conntrack: compute l3proto nla size at compile time

avoids a pointer and allows struct to be const later on.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_conntrack_l3proto.h

@@ -20,6 +20,9 @@ struct nf_conntrack_l3proto {
 	/* L3 Protocol Family number. ex) PF_INET */
 	u_int16_t l3proto;
 
+	/* size of tuple nlattr, fills a hole */
+	u16 nla_size;
+
 	/* Protocol name */
 	const char *name;
 
@@ -49,23 +52,17 @@ struct nf_conntrack_l3proto {
 	int (*get_l4proto)(const struct sk_buff *skb, unsigned int nhoff,
 			   unsigned int *dataoff, u_int8_t *protonum);
 
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 	int (*tuple_to_nlattr)(struct sk_buff *skb,
 			       const struct nf_conntrack_tuple *t);
-
-	/* Called when netns wants to use connection tracking */
-	int (*net_ns_get)(struct net *);
-	void (*net_ns_put)(struct net *);
-
-	/*
-	 * Calculate size of tuple nlattr
-	 */
-	int (*nlattr_tuple_size)(void);
-
 	int (*nlattr_to_tuple)(struct nlattr *tb[],
 			       struct nf_conntrack_tuple *t);
 	const struct nla_policy *nla_policy;
+#endif
 
-	size_t nla_size;
+	/* Called when netns wants to use connection tracking */
+	int (*net_ns_get)(struct net *);
+	void (*net_ns_put)(struct net *);
 
 	/* Module (if any) which this is connected to. */
 	struct module *me;

net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c

@@ -303,11 +303,6 @@ static int ipv4_nlattr_to_tuple(struct nlattr *tb[],
 
 	return 0;
 }
-
-static int ipv4_nlattr_tuple_size(void)
-{
-	return nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1);
-}
 #endif
 
 static struct nf_sockopt_ops so_getorigdst = {
@@ -365,9 +360,10 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
 	.get_l4proto	 = ipv4_get_l4proto,
 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 	.tuple_to_nlattr = ipv4_tuple_to_nlattr,
-	.nlattr_tuple_size = ipv4_nlattr_tuple_size,
 	.nlattr_to_tuple = ipv4_nlattr_to_tuple,
 	.nla_policy	 = ipv4_nla_policy,
+	.nla_size	 = NLA_ALIGN(NLA_HDRLEN + sizeof(u32)) + /* CTA_IP_V4_SRC */
+			   NLA_ALIGN(NLA_HDRLEN + sizeof(u32)),  /* CTA_IP_V4_DST */
 #endif
 	.net_ns_get	 = ipv4_hooks_register,
 	.net_ns_put	 = ipv4_hooks_unregister,
@@ -421,6 +417,11 @@ static int __init nf_conntrack_l3proto_ipv4_init(void)
 
 	need_conntrack();
 
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
+	if (WARN_ON(nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1) !=
+	    nf_conntrack_l3proto_ipv4.nla_size))
+		return -EINVAL;
+#endif
 	ret = nf_register_sockopt(&so_getorigdst);
 	if (ret < 0) {
 		pr_err("Unable to register netfilter socket option\n");

net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c

@@ -308,11 +308,6 @@ static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
 
 	return 0;
 }
-
-static int ipv6_nlattr_tuple_size(void)
-{
-	return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
-}
 #endif
 
 static int ipv6_hooks_register(struct net *net)
@@ -360,9 +355,10 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
 	.get_l4proto		= ipv6_get_l4proto,
 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 	.tuple_to_nlattr	= ipv6_tuple_to_nlattr,
-	.nlattr_tuple_size	= ipv6_nlattr_tuple_size,
 	.nlattr_to_tuple	= ipv6_nlattr_to_tuple,
 	.nla_policy		= ipv6_nla_policy,
+	.nla_size		= NLA_ALIGN(NLA_HDRLEN + sizeof(u32[4])) +
+				  NLA_ALIGN(NLA_HDRLEN + sizeof(u32[4])),
 #endif
 	.net_ns_get		= ipv6_hooks_register,
 	.net_ns_put		= ipv6_hooks_unregister,
@@ -421,6 +417,12 @@ static int __init nf_conntrack_l3proto_ipv6_init(void)
 
 	need_conntrack();
 
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
+	if (WARN_ON(nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1) !=
+	    nf_conntrack_l3proto_ipv6.nla_size))
+		return -EINVAL;
+#endif
+
 	ret = nf_register_sockopt(&so_getorigdst6);
 	if (ret < 0) {
 		pr_err("Unable to register netfilter socket option\n");

net/netfilter/nf_conntrack_netlink.c

@@ -540,7 +540,8 @@ static inline size_t ctnetlink_proto_size(const struct nf_conn *ct)
 	size_t len = 0;
 
 	l3proto = __nf_ct_l3proto_find(nf_ct_l3num(ct));
-	len += l3proto->nla_size;
+	len = l3proto->nla_size;
+	len *= 3u; /* ORIG, REPLY, MASTER */
 
 	l4proto = __nf_ct_l4proto_find(nf_ct_l3num(ct), nf_ct_protonum(ct));
 	len += l4proto->nla_size;

net/netfilter/nf_conntrack_proto.c

@@ -214,10 +214,10 @@ int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
 
 	if (proto->l3proto >= NFPROTO_NUMPROTO)
 		return -EBUSY;
-
-	if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
+	if (proto->tuple_to_nlattr && proto->nla_size == 0)
 		return -EINVAL;
-
+#endif
 	mutex_lock(&nf_ct_proto_mutex);
 	old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
 					lockdep_is_held(&nf_ct_proto_mutex));
@@ -226,9 +226,6 @@ int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
 		goto out_unlock;
 	}
 
-	if (proto->nlattr_tuple_size)
-		proto->nla_size = 3 * proto->nlattr_tuple_size();
-
 	rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
 
 out_unlock: