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-rw-r--r--include/net/netfilter/nf_nat.h15
-rw-r--r--net/ipv4/netfilter/iptable_nat.c4
-rw-r--r--net/ipv6/netfilter/ip6table_nat.c4
3 files changed, 23 insertions, 0 deletions
diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index bd8eea7..ad14a79 100644
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h
@@ -68,4 +68,19 @@ static inline struct nf_conn_nat *nfct_nat(const struct nf_conn *ct)
#endif
}
+static inline bool nf_nat_oif_changed(unsigned int hooknum,
+ enum ip_conntrack_info ctinfo,
+ struct nf_conn_nat *nat,
+ const struct net_device *out)
+{
+#if IS_ENABLED(CONFIG_IP_NF_TARGET_MASQUERADE) || \
+ IS_ENABLED(CONFIG_IP6_NF_TARGET_MASQUERADE)
+ return nat->masq_index && hooknum == NF_INET_POST_ROUTING &&
+ CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL &&
+ nat->masq_index != out->ifindex;
+#else
+ return false;
+#endif
+}
+
#endif
diff --git a/net/ipv4/netfilter/iptable_nat.c b/net/ipv4/netfilter/iptable_nat.c
index ac635a7..da2c8a3 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 (nf_nat_oif_changed(hooknum, ctinfo, nat, out)) {
+ nf_ct_kill_acct(ct, ctinfo, skb);
+ return NF_DROP;
+ }
}
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..6c8ae24 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 (nf_nat_oif_changed(hooknum, ctinfo, nat, out)) {
+ nf_ct_kill_acct(ct, ctinfo, skb);
+ return NF_DROP;
+ }
}
return nf_nat_packet(ct, ctinfo, hooknum, skb);
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