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   1 /* Kernel module to match the bridge port in and
   2  * out device for IP packets coming into contact with a bridge. */
   3
   4 /* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/netfilter_bridge.h>
  14 #include <linux/netfilter/xt_physdev.h>
  15 #include <linux/netfilter/x_tables.h>
  16
  17 MODULE_LICENSE("GPL");
  18 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  19 MODULE_DESCRIPTION("iptables bridge physical device match module");
  20 MODULE_ALIAS("ipt_physdev");
  21 MODULE_ALIAS("ip6t_physdev");
  22
  23 static bool
  24 match(const struct sk_buff *skb,
  25       const struct net_device *in,
  26       const struct net_device *out,
  27       const struct xt_match *match,
  28       const void *matchinfo,
  29       int offset,
  30       unsigned int protoff,
  31       bool *hotdrop)
  32 {
  33         int i;
  34         static const char nulldevname[IFNAMSIZ];
  35         const struct xt_physdev_info *info = matchinfo;
  36         bool ret;
  37         const char *indev, *outdev;
  38         const struct nf_bridge_info *nf_bridge;
  39
  40         /* Not a bridged IP packet or no info available yet:
  41          * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
  42          * the destination device will be a bridge. */
  43         if (!(nf_bridge = skb->nf_bridge)) {
  44                 /* Return MATCH if the invert flags of the used options are on */
  45                 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  46                     !(info->invert & XT_PHYSDEV_OP_BRIDGED))
  47                         return false;
  48                 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
  49                     !(info->invert & XT_PHYSDEV_OP_ISIN))
  50                         return false;
  51                 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
  52                     !(info->invert & XT_PHYSDEV_OP_ISOUT))
  53                         return false;
  54                 if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
  55                     !(info->invert & XT_PHYSDEV_OP_IN))
  56                         return false;
  57                 if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
  58                     !(info->invert & XT_PHYSDEV_OP_OUT))
  59                         return false;
  60                 return true;
  61         }
  62
  63         /* This only makes sense in the FORWARD and POSTROUTING chains */
  64         if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  65             (!!(nf_bridge->mask & BRNF_BRIDGED) ^
  66             !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
  67                 return false;
  68
  69         if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
  70             (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
  71             (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
  72             (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
  73                 return false;
  74
  75         if (!(info->bitmask & XT_PHYSDEV_OP_IN))
  76                 goto match_outdev;
  77         indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
  78         for (i = 0, ret = false; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  79                 ret |= (((const unsigned int *)indev)[i]
  80                         ^ ((const unsigned int *)info->physindev)[i])
  81                         & ((const unsigned int *)info->in_mask)[i];
  82         }
  83
  84         if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN))
  85                 return false;
  86
  87 match_outdev:
  88         if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  89                 return true;
  90         outdev = nf_bridge->physoutdev ?
  91                  nf_bridge->physoutdev->name : nulldevname;
  92         for (i = 0, ret = false; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  93                 ret |= (((const unsigned int *)outdev)[i]
  94                         ^ ((const unsigned int *)info->physoutdev)[i])
  95                         & ((const unsigned int *)info->out_mask)[i];
  96         }
  97
  98         return ret ^ !(info->invert & XT_PHYSDEV_OP_OUT);
  99 }
 100
 101 static bool
 102 checkentry(const char *tablename,
 103                        const void *ip,
 104                        const struct xt_match *match,
 105                        void *matchinfo,
 106                        unsigned int hook_mask)
 107 {
 108         const struct xt_physdev_info *info = matchinfo;
 109
 110         if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
 111             info->bitmask & ~XT_PHYSDEV_OP_MASK)
 112                 return false;
 113         if (info->bitmask & XT_PHYSDEV_OP_OUT &&
 114             (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
 115              info->invert & XT_PHYSDEV_OP_BRIDGED) &&
 116             hook_mask & ((1 << NF_IP_LOCAL_OUT) | (1 << NF_IP_FORWARD) |
 117                          (1 << NF_IP_POST_ROUTING))) {
 118                 printk(KERN_WARNING "physdev match: using --physdev-out in the "
 119                        "OUTPUT, FORWARD and POSTROUTING chains for non-bridged "
 120                        "traffic is not supported anymore.\n");
 121                 if (hook_mask & (1 << NF_IP_LOCAL_OUT))
 122                         return false;
 123         }
 124         return true;
 125 }
 126
 127 static struct xt_match xt_physdev_match[] __read_mostly = {
 128         {
 129                 .name           = "physdev",
 130                 .family         = AF_INET,
 131                 .checkentry     = checkentry,
 132                 .match          = match,
 133                 .matchsize      = sizeof(struct xt_physdev_info),
 134                 .me             = THIS_MODULE,
 135         },
 136         {
 137                 .name           = "physdev",
 138                 .family         = AF_INET6,
 139                 .checkentry     = checkentry,
 140                 .match          = match,
 141                 .matchsize      = sizeof(struct xt_physdev_info),
 142                 .me             = THIS_MODULE,
 143         },
 144 };
 145
 146 static int __init xt_physdev_init(void)
 147 {
 148         return xt_register_matches(xt_physdev_match,
 149                                    ARRAY_SIZE(xt_physdev_match));
 150 }
 151
 152 static void __exit xt_physdev_fini(void)
 153 {
 154         xt_unregister_matches(xt_physdev_match, ARRAY_SIZE(xt_physdev_match));
 155 }
 156
 157 module_init(xt_physdev_init);
 158 module_exit(xt_physdev_fini);