netfilter: ctnetlink: allow to set expectfn for expectations

This patch allows you to set expectfn which is specifically used
by the NAT side of most of the existing conntrack helpers.

I have added a symbol map that uses a string as key to look up for
the function that is attached to the expectation object. This is
the best solution I came out with to solve this issue.

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

3 files changed, 29 insertions, 0 deletions

diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index a708933dc230..abb52adf5acd 100644
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -686,6 +686,11 @@ static struct pernet_operations nf_nat_net_ops = {
 	.exit = nf_nat_net_exit,
 };
 
+static struct nf_ct_helper_expectfn follow_master_nat = {
+	.name		= "nat-follow-master",
+	.expectfn	= nf_nat_follow_master,
+};
+
 static int __init nf_nat_init(void)
 {
 	size_t i;
@@ -717,6 +722,8 @@ static int __init nf_nat_init(void)
 
 	l3proto = nf_ct_l3proto_find_get((u_int16_t)AF_INET);
 
+	nf_ct_helper_expectfn_register(&follow_master_nat);
+
 	BUG_ON(nf_nat_seq_adjust_hook != NULL);
 	RCU_INIT_POINTER(nf_nat_seq_adjust_hook, nf_nat_seq_adjust);
 	BUG_ON(nfnetlink_parse_nat_setup_hook != NULL);
@@ -736,6 +743,7 @@ static void __exit nf_nat_cleanup(void)
 	unregister_pernet_subsys(&nf_nat_net_ops);
 	nf_ct_l3proto_put(l3proto);
 	nf_ct_extend_unregister(&nat_extend);
+	nf_ct_helper_expectfn_unregister(&follow_master_nat);
 	RCU_INIT_POINTER(nf_nat_seq_adjust_hook, NULL);
 	RCU_INIT_POINTER(nfnetlink_parse_nat_setup_hook, NULL);
 	RCU_INIT_POINTER(nf_ct_nat_offset, NULL);
diff --git a/net/ipv4/netfilter/nf_nat_h323.c b/net/ipv4/netfilter/nf_nat_h323.c
index dc1dd912baf4..82536701e3a3 100644
--- a/net/ipv4/netfilter/nf_nat_h323.c
+++ b/net/ipv4/netfilter/nf_nat_h323.c
@@ -568,6 +568,16 @@ static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
 	return 0;
 }
 
+static struct nf_ct_helper_expectfn q931_nat = {
+	.name		= "Q.931",
+	.expectfn	= ip_nat_q931_expect,
+};
+
+static struct nf_ct_helper_expectfn callforwarding_nat = {
+	.name		= "callforwarding",
+	.expectfn	= ip_nat_callforwarding_expect,
+};
+
 /****************************************************************************/
 static int __init init(void)
 {
@@ -590,6 +600,8 @@ static int __init init(void)
 	RCU_INIT_POINTER(nat_h245_hook, nat_h245);
 	RCU_INIT_POINTER(nat_callforwarding_hook, nat_callforwarding);
 	RCU_INIT_POINTER(nat_q931_hook, nat_q931);
+	nf_ct_helper_expectfn_register(&q931_nat);
+	nf_ct_helper_expectfn_register(&callforwarding_nat);
 	return 0;
 }
 
@@ -605,6 +617,8 @@ static void __exit fini(void)
 	RCU_INIT_POINTER(nat_h245_hook, NULL);
 	RCU_INIT_POINTER(nat_callforwarding_hook, NULL);
 	RCU_INIT_POINTER(nat_q931_hook, NULL);
+	nf_ct_helper_expectfn_unregister(&q931_nat);
+	nf_ct_helper_expectfn_unregister(&callforwarding_nat);
 	synchronize_rcu();
 }
 
diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index d0319f96269f..57932c43960e 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -526,6 +526,11 @@ err1:
 	return NF_DROP;
 }
 
+static struct nf_ct_helper_expectfn sip_nat = {
+        .name           = "sip",
+        .expectfn       = ip_nat_sip_expected,
+};
+
 static void __exit nf_nat_sip_fini(void)
 {
 	RCU_INIT_POINTER(nf_nat_sip_hook, NULL);
@@ -535,6 +540,7 @@ static void __exit nf_nat_sip_fini(void)
 	RCU_INIT_POINTER(nf_nat_sdp_port_hook, NULL);
 	RCU_INIT_POINTER(nf_nat_sdp_session_hook, NULL);
 	RCU_INIT_POINTER(nf_nat_sdp_media_hook, NULL);
+	nf_ct_helper_expectfn_unregister(&sip_nat);
 	synchronize_rcu();
 }
 
@@ -554,6 +560,7 @@ static int __init nf_nat_sip_init(void)
 	RCU_INIT_POINTER(nf_nat_sdp_port_hook, ip_nat_sdp_port);
 	RCU_INIT_POINTER(nf_nat_sdp_session_hook, ip_nat_sdp_session);
 	RCU_INIT_POINTER(nf_nat_sdp_media_hook, ip_nat_sdp_media);
+	nf_ct_helper_expectfn_register(&sip_nat);
 	return 0;
 }