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Commit faecbb45 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
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Revert "netfilter: bridge: query conntrack about skb dnat" 



This reverts commit c055d5b0.

There are two issues:
'dnat_took_place' made me think that this is related to
-j DNAT/MASQUERADE.

But thats only one part of the story.  This is also relevant for SNAT
when we undo snat translation in reverse/reply direction.

Furthermore, I originally wanted to do this mainly to avoid
storing ipv6 addresses once we make DNAT/REDIRECT work
for ipv6 on bridges.

However, I forgot about SNPT/DNPT which is stateless.

So we can't escape storing address for ipv6 anyway. Might as
well do it for ipv4 too.

Reported-and-tested-by: default avatarBernhard Thaler <bernhard.thaler@wvnet.at>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 1086bbe9

include/linux/skbuff.h

+1 −0
Original line number Diff line number Diff line
@@ -176,6 +176,7 @@ struct nf_bridge_info { 
	struct net_device	*physindev;

	struct net_device	*physoutdev;

	char			neigh_header[8];

	__be32			ipv4_daddr;

};

#endif

net/bridge/br_netfilter.c

+9 −18
Original line number Diff line number Diff line
@@ -37,10 +37,6 @@ 
#include <net/route.h>

#include <net/netfilter/br_netfilter.h>



#if IS_ENABLED(CONFIG_NF_CONNTRACK)

#include <net/netfilter/nf_conntrack.h>

#endif



#include <asm/uaccess.h>

#include "br_private.h"

#ifdef CONFIG_SYSCTL
@@ -350,24 +346,15 @@ static int br_nf_pre_routing_finish_bridge(struct sock *sk, struct sk_buff *skb) 
	return 0;

}



static bool dnat_took_place(const struct sk_buff *skb)

static bool daddr_was_changed(const struct sk_buff *skb,

			      const struct nf_bridge_info *nf_bridge)

{

#if IS_ENABLED(CONFIG_NF_CONNTRACK)

	enum ip_conntrack_info ctinfo;

	struct nf_conn *ct;



	ct = nf_ct_get(skb, &ctinfo);

	if (!ct || nf_ct_is_untracked(ct))

		return false;



	return test_bit(IPS_DST_NAT_BIT, &ct->status);

#else

	return false;

#endif

	return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;

}



/* This requires some explaining. If DNAT has taken place,

 * we will need to fix up the destination Ethernet address.

 * This is also true when SNAT takes place (for the reply direction).

 *

 * There are two cases to consider:

 * 1. The packet was DNAT'ed to a device in the same bridge
@@ -421,7 +408,7 @@ static int br_nf_pre_routing_finish(struct sock *sk, struct sk_buff *skb) 
		nf_bridge->pkt_otherhost = false;

	}

	nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;

	if (dnat_took_place(skb)) {

	if (daddr_was_changed(skb, nf_bridge)) {

		if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {

			struct in_device *in_dev = __in_dev_get_rcu(dev);
@@ -632,6 +619,7 @@ static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops, 
				      struct sk_buff *skb,

				      const struct nf_hook_state *state)

{

	struct nf_bridge_info *nf_bridge;

	struct net_bridge_port *p;

	struct net_bridge *br;

	__u32 len = nf_bridge_encap_header_len(skb);
@@ -669,6 +657,9 @@ static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops, 
	if (!setup_pre_routing(skb))

		return NF_DROP;



	nf_bridge = nf_bridge_info_get(skb);

	nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;



	skb->protocol = htons(ETH_P_IP);



	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->sk, skb,