netfilter: nat: remove module reference counting from NAT protocols

The only remaining user of NAT protocol module reference counting is NAT
ctnetlink support. Since this is a fairly short sequence of code, convert
over to use RCU and remove module reference counting.

Module unregistration is already protected by RCU using synchronize_rcu(),
so no further changes are necessary.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 3 insertions, 22 deletions

diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index 610eb4499a1a..5e1bd85182e7 100644
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -575,26 +575,6 @@ static struct nf_ct_ext_type nat_extend __read_mostly = {
 #include <linux/netfilter/nfnetlink.h>
 #include <linux/netfilter/nfnetlink_conntrack.h>
 
-static const struct nf_nat_protocol *
-nf_nat_proto_find_get(u_int8_t protonum)
-{
-	const struct nf_nat_protocol *p;
-
-	rcu_read_lock();
-	p = __nf_nat_proto_find(protonum);
-	if (!try_module_get(p->me))
-		p = &nf_nat_unknown_protocol;
-	rcu_read_unlock();
-
-	return p;
-}
-
-static void
-nf_nat_proto_put(const struct nf_nat_protocol *p)
-{
-	module_put(p->me);
-}
-
 static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
 	[CTA_PROTONAT_PORT_MIN]	= { .type = NLA_U16 },
 	[CTA_PROTONAT_PORT_MAX]	= { .type = NLA_U16 },
@@ -612,10 +592,11 @@ static int nfnetlink_parse_nat_proto(struct nlattr *attr,
 	if (err < 0)
 		return err;
 
-	npt = nf_nat_proto_find_get(nf_ct_protonum(ct));
+	rcu_read_lock();
+	npt = __nf_nat_proto_find(nf_ct_protonum(ct));
 	if (npt->nlattr_to_range)
 		err = npt->nlattr_to_range(tb, range);
-	nf_nat_proto_put(npt);
+	rcu_read_unlock();
 	return err;
 }