netfilter: nf_conntrack: make sequence number adjustments usuable without NAT

Split out sequence number adjustments from NAT and move them to the conntrack
core to make them usable for SYN proxying. The sequence number adjustment
information is moved to a seperate extend. The extend is added to new
conntracks when a NAT mapping is set up for a connection using a helper.

As a side effect, this saves 24 bytes per connection with NAT in the common
case that a connection does not have a helper assigned.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Tested-by: Martin Topholm <mph@one.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
index 0a2e0e3e95ba..86f5b34a4ed1 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
@@ -25,6 +25,7 @@
 #include <net/netfilter/nf_conntrack_l3proto.h>
 #include <net/netfilter/nf_conntrack_zones.h>
 #include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_seqadj.h>
 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
 #include <net/netfilter/nf_nat_helper.h>
 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
@@ -136,11 +137,7 @@ static unsigned int ipv4_confirm(unsigned int hooknum,
         /* adjust seqs for loopback traffic only in outgoing direction */
         if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
             !nf_is_loopback_packet(skb)) {
-                typeof(nf_nat_seq_adjust_hook) seq_adjust;
-
-                seq_adjust = rcu_dereference(nf_nat_seq_adjust_hook);
-                if (!seq_adjust ||
-                    !seq_adjust(skb, ct, ctinfo, ip_hdrlen(skb))) {
+                if (!nf_ct_seq_adjust(skb, ct, ctinfo, ip_hdrlen(skb))) {
                         NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
                         return NF_DROP;
                 }