When the route changes (backup default route, VPNs) which affect a
masqueraded target, the packets were sent out with the outdated source
address. The patch addresses the issue by comparing the outgoing interface
directly with the masqueraded interface in the nat table.
Events are inefficient in this case, because it'd require adding route
events to the network core and then scanning the whole conntrack table
and re-checking the route for all entry.
Signed-off-by: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxxxxxx>
---
include/net/netfilter/nf_nat.h | 18 ++++++++++++++++++
net/ipv4/netfilter/iptable_nat.c | 4 ++++
net/ipv6/netfilter/ip6table_nat.c | 4 ++++
3 files changed, 26 insertions(+), 0 deletions(-)
diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index bd8eea7..fc8f1b8 100644
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h
@@ -68,4 +68,22 @@ static inline struct nf_conn_nat *nfct_nat(const struct nf_conn *ct)
#endif
}
+static inline bool nf_nat_oif_changed(const struct sk_buff *skb,
+ unsigned int hooknum,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ struct nf_conn_nat *nat,
+ const struct net_device *out)
+{
+ if (nat->masq_index && hooknum == NF_INET_POST_ROUTING &&
+ CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL &&
+ nat->masq_index != out->ifindex) {
+ /* Outgoing interface changed, destroy conntrack. */
+ nf_ct_kill_acct(cf, ctinfo, skb);
+ nf_ct_put(ct);
+ return true;
+ }
+ return false;
+}
+
#endif
diff --git a/net/ipv4/netfilter/iptable_nat.c b/net/ipv4/netfilter/iptable_nat.c
index ac635a7..4ed34ab 100644
--- a/net/ipv4/netfilter/iptable_nat.c
+++ b/net/ipv4/netfilter/iptable_nat.c
@@ -134,6 +134,10 @@ nf_nat_ipv4_fn(unsigned int hooknum,
/* ESTABLISHED */
NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
ctinfo == IP_CT_ESTABLISHED_REPLY);
+#if IS_ENABLED(CONFIG_IP_NF_TARGET_MASQUERADE)
+ if (nf_nat_oif_changed(skb, hooknum, ct, ctinfo, nat, out))
+ return NF_DROP;
+#endif
}
return nf_nat_packet(ct, ctinfo, hooknum, skb);
diff --git a/net/ipv6/netfilter/ip6table_nat.c b/net/ipv6/netfilter/ip6table_nat.c
index fa84cf8..b0036a7 100644
--- a/net/ipv6/netfilter/ip6table_nat.c
+++ b/net/ipv6/netfilter/ip6table_nat.c
@@ -137,6 +137,10 @@ nf_nat_ipv6_fn(unsigned int hooknum,
/* ESTABLISHED */
NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
ctinfo == IP_CT_ESTABLISHED_REPLY);
+#if IS_ENABLED(CONFIG_IP6_NF_TARGET_MASQUERADE)
+ if (nf_nat_oif_changed(skb, hooknum, ct, ctinfo, nat, out))
+ return NF_DROP;
+#endif
}
return nf_nat_packet(ct, ctinfo, hooknum, skb);
--
1.7.0.4
-
E-mail : kadlec@xxxxxxxxxxxxxxxxx, kadlecsik.jozsef@xxxxxxxxxxxxx
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics, Hungarian Academy of Sciences
H-1525 Budapest 114, POB. 49, Hungary
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