netfilter: nfnetlink_queue: get rid of nfnetlink_queue_ct.c

The original intention was to avoid dependencies between nfnetlink_queue and
conntrack without ifdef pollution. However, we can achieve this by moving the
conntrack dependent code into ctnetlink and keep some glue code to access the
nfq_ct indirection from nfqueue.

After this patch, the nfq_ct indirection is always compiled in the netfilter
core to avoid polluting nfqueue with ifdefs. Thus, if nf_conntrack is not
compiled this results in only 8-bytes of memory waste in x86_64.

This patch also adds ctnetlink_nfqueue_seqadj() to avoid that the nf_conn
structure layout if exposed to nf_queue, which creates another dependency with
nf_conntrack at compilation time.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 2e907335ee81..1412e3684c1c 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -348,6 +348,12 @@ int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
 }
 EXPORT_SYMBOL(skb_make_writable);
 
+/* This needs to be compiled in any case to avoid dependencies between the
+ * nfnetlink_queue code and nf_conntrack.
+ */
+struct nfq_ct_hook __rcu *nfq_ct_hook __read_mostly;
+EXPORT_SYMBOL_GPL(nfq_ct_hook);
+
 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
 /* This does not belong here, but locally generated errors need it if connection
    tracking in use: without this, connection may not be in hash table, and hence
@@ -385,9 +391,6 @@ void nf_conntrack_destroy(struct nf_conntrack *nfct)
 }
 EXPORT_SYMBOL(nf_conntrack_destroy);
 
-struct nfq_ct_hook __rcu *nfq_ct_hook __read_mostly;
-EXPORT_SYMBOL_GPL(nfq_ct_hook);
-
 /* Built-in default zone used e.g. by modules. */
 const struct nf_conntrack_zone nf_ct_zone_dflt = {
 	.id	= NF_CT_DEFAULT_ZONE_ID,