netfilter: ctnetlink: add callbacks to the per-proto nlattrs

There is added a single callback for the l3 proto helper.  The two
callbacks for the l4 protos are necessary because of the general
structure of a ctnetlink event, which is in short:

 CTA_TUPLE_ORIG
   <l3/l4-proto-attributes>
 CTA_TUPLE_REPLY
   <l3/l4-proto-attributes>
 CTA_ID
 ...
 CTA_PROTOINFO
   <l4-proto-attributes>
 CTA_TUPLE_MASTER
   <l3/l4-proto-attributes>

Therefore the formular is

 size := sizeof(generic-nlas) + 3 * sizeof(tuple_nlas) + sizeof(protoinfo_nlas)

Some of the NLAs are optional, e. g. CTA_TUPLE_MASTER, which is only
set if it's an expected connection.  But the number of optional NLAs is
small enough to prevent netlink_trim() from reallocating if calculated
properly.

Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>

2 files changed, 13 insertions, 0 deletions

diff --git a/include/net/netfilter/nf_conntrack_l3proto.h b/include/net/netfilter/nf_conntrack_l3proto.h
index 0378676c3dd8..9f99d36d5de9 100644
--- a/include/net/netfilter/nf_conntrack_l3proto.h
+++ b/include/net/netfilter/nf_conntrack_l3proto.h
@@ -53,10 +53,17 @@ struct nf_conntrack_l3proto
         int (*tuple_to_nlattr)(struct sk_buff *skb,
                                const struct nf_conntrack_tuple *t);
 
+        /*
+         * 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;
 
+        size_t nla_size;
+
 #ifdef CONFIG_SYSCTL
         struct ctl_table_header *ctl_table_header;
         struct ctl_path         *ctl_table_path;
diff --git a/include/net/netfilter/nf_conntrack_l4proto.h b/include/net/netfilter/nf_conntrack_l4proto.h
index b01070bf2f84..a120990b3b2b 100644
--- a/include/net/netfilter/nf_conntrack_l4proto.h
+++ b/include/net/netfilter/nf_conntrack_l4proto.h
@@ -64,16 +64,22 @@ struct nf_conntrack_l4proto
         /* convert protoinfo to nfnetink attributes */
         int (*to_nlattr)(struct sk_buff *skb, struct nlattr *nla,
                          const struct nf_conn *ct);
+        /* Calculate protoinfo nlattr size */
+        int (*nlattr_size)(void);
 
         /* convert nfnetlink attributes to protoinfo */
         int (*from_nlattr)(struct nlattr *tb[], struct nf_conn *ct);
 
         int (*tuple_to_nlattr)(struct sk_buff *skb,
                                const struct nf_conntrack_tuple *t);
+        /* Calculate tuple nlattr size */
+        int (*nlattr_tuple_size)(void);
         int (*nlattr_to_tuple)(struct nlattr *tb[],
                                struct nf_conntrack_tuple *t);
         const struct nla_policy *nla_policy;
 
+        size_t nla_size;
+
 #ifdef CONFIG_SYSCTL
         struct ctl_table_header **ctl_table_header;
         struct ctl_table        *ctl_table;