netfilter: ctnetlink: don't add null bindings if no nat requested

commit 0eba801b64cc8284d9024c7ece30415a2b981a72 tried to fix a race
where nat initialisation can happen after ctnetlink-created conntrack
has been created.

However, it causes the nat module(s) to be loaded needlessly on
systems that are not using NAT.

Fortunately, we do not have to create null bindings in that case.

conntracks injected via ctnetlink always have the CONFIRMED bit set,
which prevents addition of the nat extension in nf_nat_ipv4/6_fn().

We only need to make sure that either no nat extension is added
or that we've created both src and dst manips.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index ccc46fa5edbce5e52710a22ae502e49a0f59e0a5..58579634427d2fcbf7f35556424a959697b8655e 100644 (file)
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1336,6 +1336,9 @@ ctnetlink_setup_nat(struct nf_conn *ct, const struct nlattr * const cda[])
 #ifdef CONFIG_NF_NAT_NEEDED
        int ret;
 
+       if (!cda[CTA_NAT_DST] && !cda[CTA_NAT_SRC])
+               return 0;
+
        ret = ctnetlink_parse_nat_setup(ct, NF_NAT_MANIP_DST,
                                        cda[CTA_NAT_DST]);
        if (ret < 0)