From a0ecb85a2c3af73c63b6d44ce82aea52347ccf55 Mon Sep 17 00:00:00 2001 From: Jozsef Kadlecsik Date: Fri, 30 Nov 2012 12:37:26 +0000 Subject: [PATCH] netfilter: nf_nat: Handle routing changes in MASQUERADE target 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the route changes (backup default route, VPNs) which affect a masqueraded target, the packets were sent out with the outdated source address.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 Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_nat.h | 15 +++++++++++++++ net/ipv4/netfilter/iptable_nat.c | 4 ++++ net/ipv6/netfilter/ip6table_nat.c | 4 ++++ 3 files changed, 23 insertions(+) diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h index bd8eea720f2e..ad14a799fd2e 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 ac635a7b4416..da2c8a368f68 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 fa84cf8ec6bc..6c8ae24b85eb 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); -- 2.20.1