net/netfilter/xt_physdev.c

   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("Xtables: Bridge physical device match");
  20 MODULE_ALIAS("ipt_physdev");
  21 MODULE_ALIAS("ip6t_physdev");
  22
  23 static bool
  24 physdev_mt(const struct sk_buff *skb, const struct net_device *in,
  25            const struct net_device *out, const struct xt_match *match,
  26            const void *matchinfo, int offset, unsigned int protoff,
  27            bool *hotdrop)
  28 {
  29         int i;
  30         static const char nulldevname[IFNAMSIZ];
  31         const struct xt_physdev_info *info = matchinfo;
  32         bool ret;
  33         const char *indev, *outdev;
  34         const struct nf_bridge_info *nf_bridge;
  35
  36         /* Not a bridged IP packet or no info available yet:
  37          * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
  38          * the destination device will be a bridge. */
  39         if (!(nf_bridge = skb->nf_bridge)) {
  40                 /* Return MATCH if the invert flags of the used options are on */
  41                 if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  42                     !(info->invert & XT_PHYSDEV_OP_BRIDGED))
  43                         return false;
  44                 if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
  45                     !(info->invert & XT_PHYSDEV_OP_ISIN))
  46                         return false;
  47                 if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
  48                     !(info->invert & XT_PHYSDEV_OP_ISOUT))
  49                         return false;
  50                 if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
  51                     !(info->invert & XT_PHYSDEV_OP_IN))
  52                         return false;
  53                 if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
  54                     !(info->invert & XT_PHYSDEV_OP_OUT))
  55                         return false;
  56                 return true;
  57         }
  58
  59         /* This only makes sense in the FORWARD and POSTROUTING chains */
  60         if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  61             (!!(nf_bridge->mask & BRNF_BRIDGED) ^
  62             !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
  63                 return false;
  64
  65         if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
  66             (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
  67             (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
  68             (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
  69                 return false;
  70
  71         if (!(info->bitmask & XT_PHYSDEV_OP_IN))
  72                 goto match_outdev;
  73         indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
  74         for (i = 0, ret = false; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  75                 ret |= (((const unsigned int *)indev)[i]
  76                         ^ ((const unsigned int *)info->physindev)[i])
  77                         & ((const unsigned int *)info->in_mask)[i];
  78         }
  79
  80         if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN))
  81                 return false;
  82
  83 match_outdev:
  84         if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  85                 return true;
  86         outdev = nf_bridge->physoutdev ?
  87                  nf_bridge->physoutdev->name : nulldevname;
  88         for (i = 0, ret = false; i < IFNAMSIZ/sizeof(unsigned int); i++) {
  89                 ret |= (((const unsigned int *)outdev)[i]
  90                         ^ ((const unsigned int *)info->physoutdev)[i])
  91                         & ((const unsigned int *)info->out_mask)[i];
  92         }
  93
  94         return ret ^ !(info->invert & XT_PHYSDEV_OP_OUT);
  95 }
  96
  97 static bool
  98 physdev_mt_check(const char *tablename, const void *ip,
  99                  const struct xt_match *match, void *matchinfo,
 100                  unsigned int hook_mask)
 101 {
 102         const struct xt_physdev_info *info = matchinfo;
 103
 104         if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
 105             info->bitmask & ~XT_PHYSDEV_OP_MASK)
 106                 return false;
 107         if (info->bitmask & XT_PHYSDEV_OP_OUT &&
 108             (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
 109              info->invert & XT_PHYSDEV_OP_BRIDGED) &&
 110             hook_mask & ((1 << NF_INET_LOCAL_OUT) | (1 << NF_INET_FORWARD) |
 111                          (1 << NF_INET_POST_ROUTING))) {
 112                 printk(KERN_WARNING "physdev match: using --physdev-out in the "
 113                        "OUTPUT, FORWARD and POSTROUTING chains for non-bridged "
 114                        "traffic is not supported anymore.\n");
 115                 if (hook_mask & (1 << NF_INET_LOCAL_OUT))
 116                         return false;
 117         }
 118         return true;
 119 }
 120
 121 static struct xt_match physdev_mt_reg[] __read_mostly = {
 122         {
 123                 .name           = "physdev",
 124                 .family         = AF_INET,
 125                 .checkentry     = physdev_mt_check,
 126                 .match          = physdev_mt,
 127                 .matchsize      = sizeof(struct xt_physdev_info),
 128                 .me             = THIS_MODULE,
 129         },
 130         {
 131                 .name           = "physdev",
 132                 .family         = AF_INET6,
 133                 .checkentry     = physdev_mt_check,
 134                 .match          = physdev_mt,
 135                 .matchsize      = sizeof(struct xt_physdev_info),
 136                 .me             = THIS_MODULE,
 137         },
 138 };
 139
 140 static int __init physdev_mt_init(void)
 141 {
 142         return xt_register_matches(physdev_mt_reg, ARRAY_SIZE(physdev_mt_reg));
 143 }
 144
 145 static void __exit physdev_mt_exit(void)
 146 {
 147         xt_unregister_matches(physdev_mt_reg, ARRAY_SIZE(physdev_mt_reg));
 148 }
 149
 150 module_init(physdev_mt_init);
 151 module_exit(physdev_mt_exit);