/*
   *	Handle firewalling
   *	Linux ethernet bridge
   *
   *	Authors:
   *	Lennert Buytenhek               <buytenh@gnu.org>
   *	Bart De Schuymer (maintainer)	<bdschuym@pandora.be>
   *
   *	Changes:
   *	Apr 29 2003: physdev module support (bdschuym)
   *	Jun 19 2003: let arptables see bridged ARP traffic (bdschuym)
   *	Oct 06 2003: filter encapsulated IP/ARP VLAN traffic on untagged bridge
   *	             (bdschuym)
   *	Sep 01 2004: add IPv6 filtering (bdschuym)
   *
   *	This program is free software; you can redistribute it and/or
   *	modify it under the terms of the GNU General Public License
   *	as published by the Free Software Foundation; either version
   *	2 of the License, or (at your option) any later version.
   *
   *	Lennert dedicates this file to Kerstin Wurdinger.
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/ip.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>

  #include <linux/if_arp.h>

  #include <linux/if_ether.h>
  #include <linux/if_vlan.h>

  #include <linux/if_pppox.h>
  #include <linux/ppp_defs.h>

  #include <linux/netfilter_bridge.h>
  #include <linux/netfilter_ipv4.h>
  #include <linux/netfilter_ipv6.h>
  #include <linux/netfilter_arp.h>
  #include <linux/in_route.h>

  #include <linux/inetdevice.h>

  #include <net/ip.h>
  #include <net/ipv6.h>

  #include <net/route.h>

  #include <asm/uaccess.h>

  #include "br_private.h"
  #ifdef CONFIG_SYSCTL
  #include <linux/sysctl.h>
  #endif
  
  #define skb_origaddr(skb)	 (((struct bridge_skb_cb *) \
  				 (skb->nf_bridge->data))->daddr.ipv4)

  #define store_orig_dstaddr(skb)	 (skb_origaddr(skb) = ip_hdr(skb)->daddr)
  #define dnat_took_place(skb)	 (skb_origaddr(skb) != ip_hdr(skb)->daddr)

  #ifdef CONFIG_SYSCTL
  static struct ctl_table_header *brnf_sysctl_header;

  static int brnf_call_iptables __read_mostly = 1;
  static int brnf_call_ip6tables __read_mostly = 1;
  static int brnf_call_arptables __read_mostly = 1;
  static int brnf_filter_vlan_tagged __read_mostly = 1;

  static int brnf_filter_pppoe_tagged __read_mostly = 1;

  #else
  #define brnf_filter_vlan_tagged 1

  #define brnf_filter_pppoe_tagged 1

  #endif

  static inline __be16 vlan_proto(const struct sk_buff *skb)

  {
  	return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  }
  
  #define IS_VLAN_IP(skb) \
  	(skb->protocol == htons(ETH_P_8021Q) && \

  	 vlan_proto(skb) == htons(ETH_P_IP) && 	\

  	 brnf_filter_vlan_tagged)
  
  #define IS_VLAN_IPV6(skb) \
  	(skb->protocol == htons(ETH_P_8021Q) && \
  	 vlan_proto(skb) == htons(ETH_P_IPV6) &&\
  	 brnf_filter_vlan_tagged)
  
  #define IS_VLAN_ARP(skb) \
  	(skb->protocol == htons(ETH_P_8021Q) &&	\
  	 vlan_proto(skb) == htons(ETH_P_ARP) &&	\
  	 brnf_filter_vlan_tagged)

  static inline __be16 pppoe_proto(const struct sk_buff *skb)
  {
  	return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
  			    sizeof(struct pppoe_hdr)));
  }
  
  #define IS_PPPOE_IP(skb) \
  	(skb->protocol == htons(ETH_P_PPP_SES) && \
  	 pppoe_proto(skb) == htons(PPP_IP) && \
  	 brnf_filter_pppoe_tagged)
  
  #define IS_PPPOE_IPV6(skb) \
  	(skb->protocol == htons(ETH_P_PPP_SES) && \
  	 pppoe_proto(skb) == htons(PPP_IPV6) && \
  	 brnf_filter_pppoe_tagged)

  /* We need these fake structures to make netfilter happy --
   * lots of places assume that skb->dst != NULL, which isn't
   * all that unreasonable.
   *
   * Currently, we fill in the PMTU entry because netfilter
   * refragmentation needs it, and the rt_flags entry because
   * ipt_REJECT needs it.  Future netfilter modules might
   * require us to fill additional fields. */
  static struct net_device __fake_net_device = {
  	.hard_header_len	= ETH_HLEN
  };
  
  static struct rtable __fake_rtable = {
  	.u = {
  		.dst = {
  			.__refcnt		= ATOMIC_INIT(1),
  			.dev			= &__fake_net_device,
  			.path			= &__fake_rtable.u.dst,
  			.metrics		= {[RTAX_MTU - 1] = 1500},

  			.flags			= DST_NOXFRM,

  		}
  	},
  	.rt_flags	= 0,
  };

  static inline struct net_device *bridge_parent(const struct net_device *dev)
  {
  	struct net_bridge_port *port = rcu_dereference(dev->br_port);
  
  	return port ? port->br->dev : NULL;
  }

  static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
  {
  	skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
  	if (likely(skb->nf_bridge))
  		atomic_set(&(skb->nf_bridge->use), 1);
  
  	return skb->nf_bridge;
  }

  static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
  {
  	unsigned int len = nf_bridge_encap_header_len(skb);
  
  	skb_push(skb, len);
  	skb->network_header -= len;
  }
  
  static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)

  {

  	unsigned int len = nf_bridge_encap_header_len(skb);
  
  	skb_pull(skb, len);
  	skb->network_header += len;
  }

  static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
  {
  	unsigned int len = nf_bridge_encap_header_len(skb);
  
  	skb_pull_rcsum(skb, len);
  	skb->network_header += len;
  }
  
  static inline void nf_bridge_save_header(struct sk_buff *skb)
  {
  	int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);

  	skb_copy_from_linear_data_offset(skb, -header_size,
  					 skb->nf_bridge->data, header_size);

  }

  /*
   * When forwarding bridge frames, we save a copy of the original
   * header before processing.
   */
  int nf_bridge_copy_header(struct sk_buff *skb)
  {
  	int err;

  	int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);

  
  	err = skb_cow(skb, header_size);
  	if (err)
  		return err;

  	skb_copy_to_linear_data_offset(skb, -header_size,
  				       skb->nf_bridge->data, header_size);

  	__skb_push(skb, nf_bridge_encap_header_len(skb));

  	return 0;
  }

  /* PF_BRIDGE/PRE_ROUTING *********************************************/
  /* Undo the changes made for ip6tables PREROUTING and continue the
   * bridge PRE_ROUTING hook. */
  static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
  {
  	struct nf_bridge_info *nf_bridge = skb->nf_bridge;

  	if (nf_bridge->mask & BRNF_PKT_TYPE) {
  		skb->pkt_type = PACKET_OTHERHOST;
  		nf_bridge->mask ^= BRNF_PKT_TYPE;
  	}
  	nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
  
  	skb->dst = (struct dst_entry *)&__fake_rtable;
  	dst_hold(skb->dst);
  
  	skb->dev = nf_bridge->physindev;

  	nf_bridge_push_encap_header(skb);

  	NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
  		       br_handle_frame_finish, 1);
  
  	return 0;
  }
  
  static void __br_dnat_complain(void)
  {
  	static unsigned long last_complaint;
  
  	if (jiffies - last_complaint >= 5 * HZ) {
  		printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "

  		       "forwarding to be enabled
  ");

  		last_complaint = jiffies;
  	}
  }
  
  /* 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.
   *
   * There are two cases to consider:
   * 1. The packet was DNAT'ed to a device in the same bridge
   *    port group as it was received on. We can still bridge
   *    the packet.
   * 2. The packet was DNAT'ed to a different device, either
   *    a non-bridged device or another bridge port group.
   *    The packet will need to be routed.
   *
   * The correct way of distinguishing between these two cases is to
   * 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. We then call
   * skb->dst->output() 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.
   *
   * 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:
   *

   * 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
   * 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) */

  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)
  		kfree_skb(skb);
  	else {

  		nf_bridge_pull_encap_header(skb);

  		skb->dst->output(skb);

  	}

  	return 0;
  }
  
  static int br_nf_pre_routing_finish(struct sk_buff *skb)
  {
  	struct net_device *dev = skb->dev;

  	struct iphdr *iph = ip_hdr(skb);

  	struct nf_bridge_info *nf_bridge = skb->nf_bridge;

  	int err;

  	if (nf_bridge->mask & BRNF_PKT_TYPE) {
  		skb->pkt_type = PACKET_OTHERHOST;
  		nf_bridge->mask ^= BRNF_PKT_TYPE;
  	}
  	nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;

  	if (dnat_took_place(skb)) {

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

  			struct rtable *rt;

  			struct flowi fl = {
  				.nl_u = {
  					.ip4_u = {
  						 .daddr = iph->daddr,
  						 .saddr = 0,
  						 .tos = RT_TOS(iph->tos) },
  				},
  				.proto = 0,
  			};

  			struct in_device *in_dev = in_dev_get(dev);
  
  			/* If err equals -EHOSTUNREACH the error is due to a
  			 * martian destination or due to the fact that
  			 * forwarding is disabled. For most martian packets,
  			 * ip_route_output_key() will fail. It won't fail for 2 types of
  			 * martian destinations: loopback destinations and destination
  			 * 0.0.0.0. In both cases the packet will be dropped because the
  			 * destination is the loopback device and not the bridge. */
  			if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
  				goto free_skb;

  
  			if (!ip_route_output_key(&rt, &fl)) {

  				/* - Bridged-and-DNAT'ed traffic doesn't

  				 *   require ip_forwarding. */
  				if (((struct dst_entry *)rt)->dev == dev) {

  					skb->dst = (struct dst_entry *)rt;
  					goto bridged_dnat;
  				}

  				/* we are sure that forwarding is disabled, so printing
  				 * this message is no problem. Note that the packet could
  				 * still have a martian destination address, in which case
  				 * the packet could be dropped even if forwarding were enabled */

  				__br_dnat_complain();
  				dst_release((struct dst_entry *)rt);
  			}

  free_skb:

  			kfree_skb(skb);
  			return 0;
  		} else {
  			if (skb->dst->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(PF_BRIDGE, NF_BR_PRE_ROUTING,
  					       skb, skb->dev, NULL,
  					       br_nf_pre_routing_finish_bridge,
  					       1);
  				return 0;
  			}

  			memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);

  			skb->pkt_type = PACKET_HOST;
  		}
  	} else {
  		skb->dst = (struct dst_entry *)&__fake_rtable;
  		dst_hold(skb->dst);
  	}
  
  	skb->dev = nf_bridge->physindev;

  	nf_bridge_push_encap_header(skb);

  	NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
  		       br_handle_frame_finish, 1);
  
  	return 0;
  }
  
  /* Some common code for IPv4/IPv6 */

  static struct net_device *setup_pre_routing(struct sk_buff *skb)

  {
  	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
  
  	if (skb->pkt_type == PACKET_OTHERHOST) {
  		skb->pkt_type = PACKET_HOST;
  		nf_bridge->mask |= BRNF_PKT_TYPE;
  	}
  
  	nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
  	nf_bridge->physindev = skb->dev;
  	skb->dev = bridge_parent(skb->dev);

  
  	return skb->dev;

  }
  
  /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
  static int check_hbh_len(struct sk_buff *skb)
  {

  	unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);

  	u32 pkt_len;

  	const unsigned char *nh = skb_network_header(skb);
  	int off = raw - nh;

  	int len = (raw[1] + 1) << 3;

  
  	if ((raw + len) - skb->data > skb_headlen(skb))
  		goto bad;
  
  	off += 2;
  	len -= 2;
  
  	while (len > 0) {

  		int optlen = nh[off + 1] + 2;

  		switch (nh[off]) {

  		case IPV6_TLV_PAD0:
  			optlen = 1;
  			break;
  
  		case IPV6_TLV_PADN:
  			break;
  
  		case IPV6_TLV_JUMBO:

  			if (nh[off + 1] != 4 || (off & 3) != 2)

  				goto bad;

  			pkt_len = ntohl(*(__be32 *) (nh + off + 2));

  			if (pkt_len <= IPV6_MAXPLEN ||

  			    ipv6_hdr(skb)->payload_len)

  				goto bad;

  			if (pkt_len > skb->len - sizeof(struct ipv6hdr))
  				goto bad;

  			if (pskb_trim_rcsum(skb,

  					    pkt_len + sizeof(struct ipv6hdr)))

  				goto bad;

  			nh = skb_network_header(skb);

  			break;
  		default:
  			if (optlen > len)
  				goto bad;
  			break;
  		}
  		off += optlen;
  		len -= optlen;
  	}
  	if (len == 0)
  		return 0;
  bad:
  	return -1;
  
  }
  
  /* Replicate the checks that IPv6 does on packet reception and pass the packet
   * to ip6tables, which doesn't support NAT, so things are fairly simple. */
  static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,

  					   struct sk_buff *skb,
  					   const struct net_device *in,
  					   const struct net_device *out,
  					   int (*okfn)(struct sk_buff *))

  {
  	struct ipv6hdr *hdr;
  	u32 pkt_len;

  
  	if (skb->len < sizeof(struct ipv6hdr))
  		goto inhdr_error;
  
  	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  		goto inhdr_error;

  	hdr = ipv6_hdr(skb);

  
  	if (hdr->version != 6)
  		goto inhdr_error;
  
  	pkt_len = ntohs(hdr->payload_len);
  
  	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
  		if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
  			goto inhdr_error;

  		if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
  			goto inhdr_error;

  	}
  	if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))

  		goto inhdr_error;

  	nf_bridge_put(skb->nf_bridge);

  	if (!nf_bridge_alloc(skb))

  		return NF_DROP;

  	if (!setup_pre_routing(skb))
  		return NF_DROP;

  
  	NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
  		br_nf_pre_routing_finish_ipv6);
  
  	return NF_STOLEN;
  
  inhdr_error:
  	return NF_DROP;
  }
  
  /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
   * Replicate the checks that IPv4 does on packet reception.
   * Set skb->dev to the bridge device (i.e. parent of the
   * receiving device) to make netfilter happy, the REDIRECT
   * target in particular.  Save the original destination IP
   * address to be able to detect DNAT afterwards. */
  static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,

  				      const struct net_device *in,
  				      const struct net_device *out,
  				      int (*okfn)(struct sk_buff *))

  {
  	struct iphdr *iph;
  	__u32 len;
  	struct sk_buff *skb = *pskb;

  	if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
  	    IS_PPPOE_IPV6(skb)) {

  #ifdef CONFIG_SYSCTL
  		if (!brnf_call_ip6tables)
  			return NF_ACCEPT;
  #endif
  		if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
  			goto out;

  		nf_bridge_pull_encap_header_rcsum(skb);

  		return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
  	}
  #ifdef CONFIG_SYSCTL
  	if (!brnf_call_iptables)
  		return NF_ACCEPT;
  #endif

  	if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
  	    !IS_PPPOE_IP(skb))

  		return NF_ACCEPT;
  
  	if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
  		goto out;

  	nf_bridge_pull_encap_header_rcsum(skb);

  
  	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
  		goto inhdr_error;

  	iph = ip_hdr(skb);

  	if (iph->ihl < 5 || iph->version != 4)
  		goto inhdr_error;

  	if (!pskb_may_pull(skb, 4 * iph->ihl))

  		goto inhdr_error;

  	iph = ip_hdr(skb);

  	if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)

  		goto inhdr_error;
  
  	len = ntohs(iph->tot_len);

  	if (skb->len < len || len < 4 * iph->ihl)

  		goto inhdr_error;

  	pskb_trim_rcsum(skb, len);

  	nf_bridge_put(skb->nf_bridge);

  	if (!nf_bridge_alloc(skb))

  		return NF_DROP;

  	if (!setup_pre_routing(skb))
  		return NF_DROP;

  	store_orig_dstaddr(skb);
  
  	NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
  		br_nf_pre_routing_finish);
  
  	return NF_STOLEN;
  
  inhdr_error:

  //      IP_INC_STATS_BH(IpInHdrErrors);

  out:
  	return NF_DROP;
  }
  
  
  /* PF_BRIDGE/LOCAL_IN ************************************************/
  /* The packet is locally destined, which requires a real
   * dst_entry, so detach the fake one.  On the way up, the
   * packet would pass through PRE_ROUTING again (which already
   * took place when the packet entered the bridge), but we
   * register an IPv4 PRE_ROUTING 'sabotage' hook that will
   * prevent this from happening. */
  static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff **pskb,

  				   const struct net_device *in,
  				   const struct net_device *out,
  				   int (*okfn)(struct sk_buff *))

  {
  	struct sk_buff *skb = *pskb;
  
  	if (skb->dst == (struct dst_entry *)&__fake_rtable) {
  		dst_release(skb->dst);
  		skb->dst = NULL;
  	}
  
  	return NF_ACCEPT;
  }

  /* PF_BRIDGE/FORWARD *************************************************/
  static int br_nf_forward_finish(struct sk_buff *skb)
  {
  	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
  	struct net_device *in;

  	if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {

  		in = nf_bridge->physindev;
  		if (nf_bridge->mask & BRNF_PKT_TYPE) {
  			skb->pkt_type = PACKET_OTHERHOST;
  			nf_bridge->mask ^= BRNF_PKT_TYPE;
  		}
  	} else {
  		in = *((struct net_device **)(skb->cb));
  	}

  	nf_bridge_push_encap_header(skb);

  	NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,

  		       skb->dev, br_forward_finish, 1);

  	return 0;
  }
  
  /* This is the 'purely bridged' case.  For IP, we pass the packet to
   * netfilter with indev and outdev set to the bridge device,
   * but we are still able to filter on the 'real' indev/outdev
   * because of the physdev module. For ARP, indev and outdev are the
   * bridge ports. */
  static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,

  				     const struct net_device *in,
  				     const struct net_device *out,
  				     int (*okfn)(struct sk_buff *))

  {
  	struct sk_buff *skb = *pskb;
  	struct nf_bridge_info *nf_bridge;

  	struct net_device *parent;

  	int pf;
  
  	if (!skb->nf_bridge)
  		return NF_ACCEPT;

  	parent = bridge_parent(out);
  	if (!parent)
  		return NF_DROP;

  	if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
  	    IS_PPPOE_IP(skb))

  		pf = PF_INET;
  	else
  		pf = PF_INET6;

  	nf_bridge_pull_encap_header(*pskb);

  	nf_bridge = skb->nf_bridge;
  	if (skb->pkt_type == PACKET_OTHERHOST) {
  		skb->pkt_type = PACKET_HOST;
  		nf_bridge->mask |= BRNF_PKT_TYPE;
  	}
  
  	/* The physdev module checks on this */
  	nf_bridge->mask |= BRNF_BRIDGED;
  	nf_bridge->physoutdev = skb->dev;

  	NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in), parent,
  		br_nf_forward_finish);

  
  	return NF_STOLEN;
  }
  
  static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff **pskb,

  				      const struct net_device *in,
  				      const struct net_device *out,
  				      int (*okfn)(struct sk_buff *))

  {
  	struct sk_buff *skb = *pskb;

  	struct net_device **d = (struct net_device **)(skb->cb);
  
  #ifdef CONFIG_SYSCTL
  	if (!brnf_call_arptables)
  		return NF_ACCEPT;
  #endif

  	if (skb->protocol != htons(ETH_P_ARP)) {

  		if (!IS_VLAN_ARP(skb))

  			return NF_ACCEPT;

  		nf_bridge_pull_encap_header(*pskb);

  	}

  	if (arp_hdr(skb)->ar_pln != 4) {

  		if (IS_VLAN_ARP(skb))
  			nf_bridge_push_encap_header(*pskb);

  		return NF_ACCEPT;
  	}
  	*d = (struct net_device *)in;
  	NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
  		(struct net_device *)out, br_nf_forward_finish);
  
  	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 **pskb,

  				    const struct net_device *in,
  				    const struct net_device *out,
  				    int (*okfn)(struct sk_buff *))

  {

  	struct net_device *realindev;

  	struct sk_buff *skb = *pskb;
  	struct nf_bridge_info *nf_bridge;

  
  	if (!skb->nf_bridge)
  		return NF_ACCEPT;

  	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(PF_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev,
  		br_forward_finish);

  	return NF_STOLEN;
  }

  static int br_nf_dev_queue_xmit(struct sk_buff *skb)
  {
  	if (skb->protocol == htons(ETH_P_IP) &&
  	    skb->len > skb->dev->mtu &&

  	    !skb_is_gso(skb))

  		return ip_fragment(skb, br_dev_queue_push_xmit);
  	else
  		return br_dev_queue_push_xmit(skb);
  }

  
  /* PF_BRIDGE/POST_ROUTING ********************************************/
  static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,

  				       const struct net_device *in,
  				       const struct net_device *out,
  				       int (*okfn)(struct sk_buff *))

  {
  	struct sk_buff *skb = *pskb;
  	struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge;

  	struct net_device *realoutdev = bridge_parent(skb->dev);
  	int pf;
  
  #ifdef CONFIG_NETFILTER_DEBUG
  	/* Be very paranoid. This probably won't happen anymore, but let's
  	 * keep the check just to be sure... */

  	if (skb_mac_header(skb) < skb->head ||
  	    skb_mac_header(skb) + ETH_HLEN > skb->data) {

  		printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "

  		       "bad mac.raw pointer.
  ");

  		goto print_error;
  	}
  #endif
  
  	if (!nf_bridge)
  		return NF_ACCEPT;

  	if (!realoutdev)
  		return NF_DROP;

  	if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
  	    IS_PPPOE_IP(skb))

  		pf = PF_INET;
  	else
  		pf = PF_INET6;
  
  #ifdef CONFIG_NETFILTER_DEBUG
  	if (skb->dst == NULL) {

  		printk(KERN_INFO "br_netfilter post_routing: skb->dst == NULL
  ");

  		goto print_error;
  	}

  #endif
  
  	/* We assume any code from br_dev_queue_push_xmit onwards doesn't care
  	 * about the value of skb->pkt_type. */
  	if (skb->pkt_type == PACKET_OTHERHOST) {
  		skb->pkt_type = PACKET_HOST;
  		nf_bridge->mask |= BRNF_PKT_TYPE;
  	}

  	nf_bridge_pull_encap_header(skb);

  	nf_bridge_save_header(skb);
  
  #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
  	if (nf_bridge->netoutdev)
  		realoutdev = nf_bridge->netoutdev;
  #endif
  	NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev,

  		br_nf_dev_queue_xmit);

  
  	return NF_STOLEN;
  
  #ifdef CONFIG_NETFILTER_DEBUG
  print_error:
  	if (skb->dev != NULL) {
  		printk("[%s]", skb->dev->name);

  		if (realoutdev)
  			printk("[%s]", realoutdev->name);

  	}

  	printk(" head:%p, raw:%p, data:%p
  ", skb->head, skb_mac_header(skb),

  	       skb->data);

  	dump_stack();

  	return NF_ACCEPT;
  #endif
  }

  /* IP/SABOTAGE *****************************************************/
  /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
   * for the second time. */
  static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff **pskb,

  				   const struct net_device *in,
  				   const struct net_device *out,
  				   int (*okfn)(struct sk_buff *))

  {
  	if ((*pskb)->nf_bridge &&
  	    !((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
  		return NF_STOP;
  	}
  
  	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. */
  static struct nf_hook_ops br_nf_ops[] = {

  	{ .hook = br_nf_pre_routing,
  	  .owner = THIS_MODULE,
  	  .pf = PF_BRIDGE,
  	  .hooknum = NF_BR_PRE_ROUTING,

  	  .priority = NF_BR_PRI_BRNF, },
  	{ .hook = br_nf_local_in,
  	  .owner = THIS_MODULE,
  	  .pf = PF_BRIDGE,
  	  .hooknum = NF_BR_LOCAL_IN,
  	  .priority = NF_BR_PRI_BRNF, },
  	{ .hook = br_nf_forward_ip,
  	  .owner = THIS_MODULE,
  	  .pf = PF_BRIDGE,
  	  .hooknum = NF_BR_FORWARD,
  	  .priority = NF_BR_PRI_BRNF - 1, },
  	{ .hook = br_nf_forward_arp,
  	  .owner = THIS_MODULE,
  	  .pf = PF_BRIDGE,
  	  .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,
  	  .pf = PF_BRIDGE,
  	  .hooknum = NF_BR_POST_ROUTING,
  	  .priority = NF_BR_PRI_LAST, },
  	{ .hook = ip_sabotage_in,
  	  .owner = THIS_MODULE,
  	  .pf = PF_INET,
  	  .hooknum = NF_IP_PRE_ROUTING,
  	  .priority = NF_IP_PRI_FIRST, },
  	{ .hook = ip_sabotage_in,
  	  .owner = THIS_MODULE,
  	  .pf = PF_INET6,
  	  .hooknum = NF_IP6_PRE_ROUTING,
  	  .priority = NF_IP6_PRI_FIRST, },

  };
  
  #ifdef CONFIG_SYSCTL
  static

  int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp,
  			    void __user * buffer, size_t * lenp, loff_t * ppos)

  {
  	int ret;
  
  	ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
  
  	if (write && *(int *)(ctl->data))
  		*(int *)(ctl->data) = 1;
  	return ret;
  }
  
  static ctl_table brnf_table[] = {
  	{
  		.ctl_name	= NET_BRIDGE_NF_CALL_ARPTABLES,
  		.procname	= "bridge-nf-call-arptables",
  		.data		= &brnf_call_arptables,
  		.maxlen		= sizeof(int),
  		.mode		= 0644,
  		.proc_handler	= &brnf_sysctl_call_tables,
  	},
  	{
  		.ctl_name	= NET_BRIDGE_NF_CALL_IPTABLES,
  		.procname	= "bridge-nf-call-iptables",
  		.data		= &brnf_call_iptables,
  		.maxlen		= sizeof(int),
  		.mode		= 0644,
  		.proc_handler	= &brnf_sysctl_call_tables,
  	},
  	{
  		.ctl_name	= NET_BRIDGE_NF_CALL_IP6TABLES,
  		.procname	= "bridge-nf-call-ip6tables",
  		.data		= &brnf_call_ip6tables,
  		.maxlen		= sizeof(int),
  		.mode		= 0644,
  		.proc_handler	= &brnf_sysctl_call_tables,
  	},
  	{
  		.ctl_name	= NET_BRIDGE_NF_FILTER_VLAN_TAGGED,
  		.procname	= "bridge-nf-filter-vlan-tagged",
  		.data		= &brnf_filter_vlan_tagged,
  		.maxlen		= sizeof(int),
  		.mode		= 0644,
  		.proc_handler	= &brnf_sysctl_call_tables,

  	},
  	{
  		.ctl_name	= NET_BRIDGE_NF_FILTER_PPPOE_TAGGED,
  		.procname	= "bridge-nf-filter-pppoe-tagged",
  		.data		= &brnf_filter_pppoe_tagged,
  		.maxlen		= sizeof(int),
  		.mode		= 0644,
  		.proc_handler	= &brnf_sysctl_call_tables,

  	},
  	{ .ctl_name = 0 }
  };
  
  static ctl_table brnf_bridge_table[] = {
  	{
  		.ctl_name	= NET_BRIDGE,
  		.procname	= "bridge",
  		.mode		= 0555,
  		.child		= brnf_table,
  	},
  	{ .ctl_name = 0 }
  };
  
  static ctl_table brnf_net_table[] = {
  	{
  		.ctl_name	= CTL_NET,
  		.procname	= "net",
  		.mode		= 0555,
  		.child		= brnf_bridge_table,
  	},
  	{ .ctl_name = 0 }
  };
  #endif

  int __init br_netfilter_init(void)

  {

  	int ret;

  	ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
  	if (ret < 0)

  		return ret;

  #ifdef CONFIG_SYSCTL

  	brnf_sysctl_header = register_sysctl_table(brnf_net_table);

  	if (brnf_sysctl_header == NULL) {

  		printk(KERN_WARNING
  		       "br_netfilter: can't register to sysctl.
  ");

  		nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
  		return -ENOMEM;

  	}
  #endif

  	printk(KERN_NOTICE "Bridge firewalling registered
  ");

  	return 0;
  }
  
  void br_netfilter_fini(void)
  {

  	nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));

  #ifdef CONFIG_SYSCTL
  	unregister_sysctl_table(brnf_sysctl_header);
  #endif
  }