text: /* Kernel module to match the bridge port in and
   * out device for IP packets coming into contact with a bridge. */
  
  /* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/module.h>
  #include <linux/skbuff.h>
  #include <linux/netfilter_bridge.h>
  #include <linux/netfilter/xt_physdev.h>
  #include <linux/netfilter/x_tables.h>
  #include <linux/netfilter_bridge.h>
  #define MATCH   1
  #define NOMATCH 0
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  MODULE_DESCRIPTION("iptables bridge physical device match module");
  MODULE_ALIAS("ipt_physdev");
  MODULE_ALIAS("ip6t_physdev");
  
  static int
  match(const struct sk_buff *skb,
        const struct net_device *in,
        const struct net_device *out,
        const struct xt_match *match,
        const void *matchinfo,
        int offset,
        unsigned int protoff,
        int *hotdrop)
  {
  	int i;
  	static const char nulldevname[IFNAMSIZ];
  	const struct xt_physdev_info *info = matchinfo;
  	unsigned int ret;
  	const char *indev, *outdev;
  	struct nf_bridge_info *nf_bridge;
  
  	/* Not a bridged IP packet or no info available yet:
  	 * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
  	 * the destination device will be a bridge. */
  	if (!(nf_bridge = skb->nf_bridge)) {
  		/* Return MATCH if the invert flags of the used options are on */
  		if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  		    !(info->invert & XT_PHYSDEV_OP_BRIDGED))
  			return NOMATCH;
  		if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
  		    !(info->invert & XT_PHYSDEV_OP_ISIN))
  			return NOMATCH;
  		if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
  		    !(info->invert & XT_PHYSDEV_OP_ISOUT))
  			return NOMATCH;
  		if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
  		    !(info->invert & XT_PHYSDEV_OP_IN))
  			return NOMATCH;
  		if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
  		    !(info->invert & XT_PHYSDEV_OP_OUT))
  			return NOMATCH;
  		return MATCH;
  	}
  
  	/* This only makes sense in the FORWARD and POSTROUTING chains */
  	if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  	    (!!(nf_bridge->mask & BRNF_BRIDGED) ^
  	    !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
  		return NOMATCH;
  
  	if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
  	    (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
  	    (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
  	    (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
  		return NOMATCH;
  
  	if (!(info->bitmask & XT_PHYSDEV_OP_IN))
  		goto match_outdev;
  	indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
  	for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  		ret |= (((const unsigned int *)indev)[i]
  			^ ((const unsigned int *)info->physindev)[i])
  			& ((const unsigned int *)info->in_mask)[i];
  	}
  
  	if ((ret == 0) ^ !(info->invert & XT_PHYSDEV_OP_IN))
  		return NOMATCH;
  
  match_outdev:
  	if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  		return MATCH;
  	outdev = nf_bridge->physoutdev ?
  		 nf_bridge->physoutdev->name : nulldevname;
  	for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  		ret |= (((const unsigned int *)outdev)[i]
  			^ ((const unsigned int *)info->physoutdev)[i])
  			& ((const unsigned int *)info->out_mask)[i];
  	}
  
  	return (ret != 0) ^ !(info->invert & XT_PHYSDEV_OP_OUT);
  }
  
  static int
  checkentry(const char *tablename,
  		       const void *ip,
  		       const struct xt_match *match,
  		       void *matchinfo,
  		       unsigned int hook_mask)
  {
  	const struct xt_physdev_info *info = matchinfo;
  
  	if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
  	    info->bitmask & ~XT_PHYSDEV_OP_MASK)
  		return 0;
  	if (info->bitmask & XT_PHYSDEV_OP_OUT &&
  	    (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
  	     info->invert & XT_PHYSDEV_OP_BRIDGED) &&
  	    hook_mask & ((1 << NF_IP_LOCAL_OUT) | (1 << NF_IP_FORWARD) |
  			 (1 << NF_IP_POST_ROUTING))) {
  		printk(KERN_WARNING "physdev match: using --physdev-out in the "
  		       "OUTPUT, FORWARD and POSTROUTING chains for non-bridged "
  		       "traffic is not supported anymore.\n");
  		if (hook_mask & (1 << NF_IP_LOCAL_OUT))
  			return 0;
  	}
  	return 1;
  }
  
  static struct xt_match xt_physdev_match[] = {
  	{
  		.name		= "physdev",
  		.family		= AF_INET,
  		.checkentry	= checkentry,
  		.match		= match,
  		.matchsize	= sizeof(struct xt_physdev_info),
  		.me		= THIS_MODULE,
  	},
  	{
  		.name		= "physdev",
  		.family		= AF_INET6,
  		.checkentry	= checkentry,
  		.match		= match,
  		.matchsize	= sizeof(struct xt_physdev_info),
  		.me		= THIS_MODULE,
  	},
  };
  
  static int __init xt_physdev_init(void)
  {
  	return xt_register_matches(xt_physdev_match,
  				   ARRAY_SIZE(xt_physdev_match));
  }
  
  static void __exit xt_physdev_fini(void)
  {
  	xt_unregister_matches(xt_physdev_match, ARRAY_SIZE(xt_physdev_match));
  }
  
  module_init(xt_physdev_init);
  module_exit(xt_physdev_fini);
  