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