netfilter: conntrack: don't cache nlattr_tuple_size result in nla_size

We currently call ->nlattr_tuple_size() once at register time and
cache result in l4proto->nla_size.

nla_size is the only member that is written to, avoiding this would
allow to make l4proto trackers const.

We can use ->nlattr_tuple_size() at run time, and cache result in
the individual trackers instead.

This is an intermediate step, next patch removes nlattr_size()
callback and computes size at compile time, then removes nla_size.

Signed-off-by: Florian Westphal <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

include/net/netfilter/nf_conntrack_l4proto.h

···
 	int (*tuple_to_nlattr)(struct sk_buff *skb,
 			       const struct nf_conntrack_tuple *t);
 	/* Calculate tuple nlattr size */
-	int (*nlattr_tuple_size)(void);
+	unsigned int (*nlattr_tuple_size)(void);
 	int (*nlattr_to_tuple)(struct nlattr *tb[],
 			       struct nf_conntrack_tuple *t);
 	const struct nla_policy *nla_policy;
···
 			       const struct nf_conntrack_tuple *tuple);
 int nf_ct_port_nlattr_to_tuple(struct nlattr *tb[],
 			       struct nf_conntrack_tuple *t);
-int nf_ct_port_nlattr_tuple_size(void);
+unsigned int nf_ct_port_nlattr_tuple_size(void);
 extern const struct nla_policy nf_ct_port_nla_policy[];
 
 #ifdef CONFIG_SYSCTL

net/ipv4/netfilter/nf_conntrack_proto_icmp.c

···
 	return 0;
 }
 
-static int icmp_nlattr_tuple_size(void)
+static unsigned int icmp_nlattr_tuple_size(void)
 {
-	return nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1);
+	static unsigned int size __read_mostly;
+
+	if (!size)
+		size = nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1);
+
+	return size;
 }
 #endif
 

net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c

···
 	return 0;
 }
 
-static int icmpv6_nlattr_tuple_size(void)
+static unsigned int icmpv6_nlattr_tuple_size(void)
 {
-	return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
+	static unsigned int size __read_mostly;
+
+	if (!size)
+		size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
+
+	return size;
 }
 #endif
 

net/netfilter/nf_conntrack_core.c

···
 }
 EXPORT_SYMBOL_GPL(nf_ct_port_nlattr_to_tuple);
 
-int nf_ct_port_nlattr_tuple_size(void)
+unsigned int nf_ct_port_nlattr_tuple_size(void)
 {
-	return nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
+	static unsigned int size __read_mostly;
+
+	if (!size)
+		size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
+
+	return size;
 }
 EXPORT_SYMBOL_GPL(nf_ct_port_nlattr_tuple_size);
 #endif

net/netfilter/nf_conntrack_netlink.c

···
 	return -1;
 }
 
-static inline size_t ctnetlink_proto_size(const struct nf_conn *ct)
+static size_t ctnetlink_proto_size(const struct nf_conn *ct)
 {
 	const struct nf_conntrack_l3proto *l3proto;
 	const struct nf_conntrack_l4proto *l4proto;
-	size_t len;
+	size_t len, len4 = 0;
 
 	l3proto = __nf_ct_l3proto_find(nf_ct_l3num(ct));
 	len = l3proto->nla_size;
···
 
 	l4proto = __nf_ct_l4proto_find(nf_ct_l3num(ct), nf_ct_protonum(ct));
 	len += l4proto->nla_size;
+	if (l4proto->nlattr_tuple_size) {
+		len4 = l4proto->nlattr_tuple_size();
+		len4 *= 3u; /* ORIG, REPLY, MASTER */
+	}
 
-	return len;
+	return len + len4;
 }
 
 static inline size_t ctnetlink_acct_size(const struct nf_conn *ct)

net/netfilter/nf_conntrack_proto.c

···
 	l4proto->nla_size = 0;
 	if (l4proto->nlattr_size)
 		l4proto->nla_size += l4proto->nlattr_size();
-	if (l4proto->nlattr_tuple_size)
-		l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
 
 	rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
 			   l4proto);

net/netfilter/nf_conntrack_proto_tcp.c

···
 		+ nla_policy_len(tcp_nla_policy, CTA_PROTOINFO_TCP_MAX + 1);
 }
 
-static int tcp_nlattr_tuple_size(void)
+static unsigned int tcp_nlattr_tuple_size(void)
 {
-	return nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
+	static unsigned int size __read_mostly;
+
+	if (!size)
+		size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
+
+	return size;
 }
 #endif