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Commit ea2d9b41 authored by Bart De Schuymer's avatar Bart De Schuymer Committed by Patrick McHardy
Browse files

netfilter: bridge-netfilter: simplify IP DNAT 



Remove br_netfilter.c::br_nf_local_out(). The function
br_nf_local_out() was needed because the PF_BRIDGE::LOCAL_OUT hook
could be called when IP DNAT happens on to-be-bridged traffic. The
new scheme eliminates this mess.

Signed-off-by: default avatarBart De Schuymer <bdschuym@pandora.be>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
parent 9c6eb28a

include/linux/netfilter_bridge.h

+14 −3
Original line number Diff line number Diff line
@@ -41,9 +41,8 @@ enum nf_br_hook_priorities { 


#define BRNF_PKT_TYPE			0x01

#define BRNF_BRIDGED_DNAT		0x02

#define BRNF_DONT_TAKE_PARENT		0x04

#define BRNF_BRIDGED			0x08

#define BRNF_NF_BRIDGE_PREROUTING	0x10

#define BRNF_BRIDGED			0x04

#define BRNF_NF_BRIDGE_PREROUTING	0x08





/* Only used in br_forward.c */
@@ -68,6 +67,18 @@ static inline unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb) 
	}

}



extern int br_handle_frame_finish(struct sk_buff *skb);

/* Only used in br_device.c */

static inline int br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)

{

	struct nf_bridge_info *nf_bridge = skb->nf_bridge;



	skb_pull(skb, ETH_HLEN);

	nf_bridge->mask ^= BRNF_BRIDGED_DNAT;

	skb->dev = nf_bridge->physindev;

	return br_handle_frame_finish(skb);

}



/* This is called by the IP fragmenting code and it ensures there is

 * enough room for the encapsulating header (if there is one). */

static inline unsigned int nf_bridge_pad(const struct sk_buff *skb)

net/bridge/br_device.c

+8 −1
Original line number Diff line number Diff line
@@ -15,7 +15,7 @@ 
#include <linux/netdevice.h>

#include <linux/etherdevice.h>

#include <linux/ethtool.h>



#include <linux/netfilter_bridge.h>

#include <asm/uaccess.h>

#include "br_private.h"
@@ -28,6 +28,13 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev) 
	struct net_bridge_mdb_entry *mdst;

	struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);



#ifdef CONFIG_BRIDGE_NETFILTER

	if (skb->nf_bridge && (skb->nf_bridge->mask & BRNF_BRIDGED_DNAT)) {

		br_nf_pre_routing_finish_bridge_slow(skb);

		return NETDEV_TX_OK;

	}

#endif



	brstats->tx_packets++;

	brstats->tx_bytes += skb->len;

net/bridge/br_netfilter.c

+18 −96
Original line number Diff line number Diff line
@@ -246,8 +246,7 @@ static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb) 
}



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

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

 * and this is a tricky process.

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

 *

 * There are two cases to consider:

 * 1. The packet was DNAT'ed to a device in the same bridge
@@ -261,52 +260,38 @@ static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb) 
 * call ip_route_input() and to look at skb->dst->dev, which is

 * changed to the destination device if ip_route_input() succeeds.

 *

 * Let us first consider the case that ip_route_input() succeeds:

 *

 * If skb->dst->dev equals the logical bridge device the packet

 * came in on, we can consider this bridging. The packet is passed

 * through the neighbour output function to build a new destination

 * MAC address, which will make the packet enter br_nf_local_out()

 * not much later. In that function it is assured that the iptables

 * FORWARD chain is traversed for the packet.

 * Let's first consider the case that ip_route_input() succeeds:

 *

 * If the output device equals the logical bridge device the packet

 * came in on, we can consider this bridging. The corresponding MAC

 * address will be obtained in br_nf_pre_routing_finish_bridge.

 * Otherwise, the packet is considered to be routed and we just

 * change the destination MAC address so that the packet will

 * later be passed up to the IP stack to be routed. For a redirected

 * packet, ip_route_input() will give back the localhost as output device,

 * which differs from the bridge device.

 *

 * Let us now consider the case that ip_route_input() fails:

 * Let's now consider the case that ip_route_input() fails:

 *

 * This can be because the destination address is martian, in which case

 * the packet will be dropped.

 * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()

 * will fail, while __ip_route_output_key() will return success. The source

 * address for __ip_route_output_key() is set to zero, so __ip_route_output_key

 * If IP forwarding is disabled, ip_route_input() will fail, while

 * ip_route_output_key() can return success. The source

 * address for ip_route_output_key() is set to zero, so ip_route_output_key()

 * thinks we're handling a locally generated packet and won't care

 * if IP forwarding is allowed. We send a warning message to the users's

 * log telling her to put IP forwarding on.

 *

 * ip_route_input() will also fail if there is no route available.

 * In that case we just drop the packet.

 *

 * --Lennert, 20020411

 * --Bart, 20020416 (updated)

 * --Bart, 20021007 (updated)

 * --Bart, 20062711 (updated) */

 * if IP forwarding is enabled. If the output device equals the logical bridge

 * device, we proceed as if ip_route_input() succeeded. If it differs from the

 * logical bridge port or if ip_route_output_key() fails we drop the packet.

 */



static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)

{

	if (skb->pkt_type == PACKET_OTHERHOST) {

		skb->pkt_type = PACKET_HOST;

		skb->nf_bridge->mask |= BRNF_PKT_TYPE;

	}

	skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;



	skb->dev = bridge_parent(skb->dev);

	if (skb->dev) {

		struct dst_entry *dst = skb_dst(skb);



		nf_bridge_pull_encap_header(skb);

		skb->nf_bridge->mask |= BRNF_BRIDGED_DNAT;



		if (dst->hh)

			return neigh_hh_output(dst->hh, skb);
@@ -368,9 +353,6 @@ static int br_nf_pre_routing_finish(struct sk_buff *skb) 
		} else {

			if (skb_dst(skb)->dev == dev) {

bridged_dnat:

				/* Tell br_nf_local_out this is a

				 * bridged frame */

				nf_bridge->mask |= BRNF_BRIDGED_DNAT;

				skb->dev = nf_bridge->physindev;

				nf_bridge_push_encap_header(skb);

				NF_HOOK_THRESH(NFPROTO_BRIDGE,
@@ -721,54 +703,6 @@ static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb, 
	return NF_STOLEN;

}



/* PF_BRIDGE/LOCAL_OUT ***********************************************

 *

 * This function sees both locally originated IP packets and forwarded

 * IP packets (in both cases the destination device is a bridge

 * device). It also sees bridged-and-DNAT'ed packets.

 *

 * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged

 * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()

 * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority

 * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor

 * will be executed.

 */

static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,

				    const struct net_device *in,

				    const struct net_device *out,

				    int (*okfn)(struct sk_buff *))

{

	struct net_device *realindev;

	struct nf_bridge_info *nf_bridge;



	if (!skb->nf_bridge)

		return NF_ACCEPT;



	/* Need exclusive nf_bridge_info since we might have multiple

	 * different physoutdevs. */

	if (!nf_bridge_unshare(skb))

		return NF_DROP;



	nf_bridge = skb->nf_bridge;

	if (!(nf_bridge->mask & BRNF_BRIDGED_DNAT))

		return NF_ACCEPT;



	/* Bridged, take PF_BRIDGE/FORWARD.

	 * (see big note in front of br_nf_pre_routing_finish) */

	nf_bridge->physoutdev = skb->dev;

	realindev = nf_bridge->physindev;



	if (nf_bridge->mask & BRNF_PKT_TYPE) {

		skb->pkt_type = PACKET_OTHERHOST;

		nf_bridge->mask ^= BRNF_PKT_TYPE;

	}

	nf_bridge_push_encap_header(skb);



	NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev,

		br_forward_finish);

	return NF_STOLEN;

}



#if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)

static int br_nf_dev_queue_xmit(struct sk_buff *skb)

{
@@ -797,10 +731,7 @@ static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb, 
	struct net_device *realoutdev = bridge_parent(skb->dev);

	u_int8_t pf;



	if (!nf_bridge)

		return NF_ACCEPT;



	if (!(nf_bridge->mask & (BRNF_BRIDGED | BRNF_BRIDGED_DNAT)))

	if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED))

		return NF_ACCEPT;



	if (!realoutdev)
@@ -847,10 +778,8 @@ static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb, 
	return NF_ACCEPT;

}



/* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent

 * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.

 * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because

 * ip_refrag() can return NF_STOLEN. */

/* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because

 * br_dev_queue_push_xmit is called afterwards */

static struct nf_hook_ops br_nf_ops[] __read_mostly = {

	{

		.hook = br_nf_pre_routing,
@@ -880,13 +809,6 @@ static struct nf_hook_ops br_nf_ops[] __read_mostly = { 
		.hooknum = NF_BR_FORWARD,

		.priority = NF_BR_PRI_BRNF,

	},

	{

		.hook = br_nf_local_out,

		.owner = THIS_MODULE,

		.pf = PF_BRIDGE,

		.hooknum = NF_BR_LOCAL_OUT,

		.priority = NF_BR_PRI_FIRST,

	},

	{

		.hook = br_nf_post_routing,

		.owner = THIS_MODULE,