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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  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
  24 static bool
  25 physdev_mt(const struct sk_buff *skb, struct xt_action_param *par)
  26 {
  27         static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
  28         const struct xt_physdev_info *info = par->matchinfo;
  29         unsigned long 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         ret = ifname_compare_aligned(indev, info->physindev, info->in_mask);
  72
  73         if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN))
  74                 return false;
  75
  76 match_outdev:
  77         if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  78                 return true;
  79         outdev = nf_bridge->physoutdev ?
  80                  nf_bridge->physoutdev->name : nulldevname;
  81         ret = ifname_compare_aligned(outdev, info->physoutdev, info->out_mask);
  82
  83         return (!!ret ^ !(info->invert & XT_PHYSDEV_OP_OUT));
  84 }
  85
  86 static int physdev_mt_check(const struct xt_mtchk_param *par)
  87 {
  88         const struct xt_physdev_info *info = par->matchinfo;
  89
  90         if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
  91             info->bitmask & ~XT_PHYSDEV_OP_MASK)
  92                 return -EINVAL;
  93         if (info->bitmask & XT_PHYSDEV_OP_OUT &&
  94             (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
  95              info->invert & XT_PHYSDEV_OP_BRIDGED) &&
  96             par->hook_mask & ((1 << NF_INET_LOCAL_OUT) |
  97             (1 << NF_INET_FORWARD) | (1 << NF_INET_POST_ROUTING))) {
  98                 pr_info("using --physdev-out in the OUTPUT, FORWARD and "
  99                         "POSTROUTING chains for non-bridged traffic is not "
 100                         "supported anymore.\n");
 101                 if (par->hook_mask & (1 << NF_INET_LOCAL_OUT))
 102                         return -EINVAL;
 103         }
 104         return 0;
 105 }
 106
 107 static struct xt_match physdev_mt_reg __read_mostly = {
 108         .name       = "physdev",
 109         .revision   = 0,
 110         .family     = NFPROTO_UNSPEC,
 111         .checkentry = physdev_mt_check,
 112         .match      = physdev_mt,
 113         .matchsize  = sizeof(struct xt_physdev_info),
 114         .me         = THIS_MODULE,
 115 };
 116
 117 static int __init physdev_mt_init(void)
 118 {
 119         return xt_register_match(&physdev_mt_reg);
 120 }
 121
 122 static void __exit physdev_mt_exit(void)
 123 {
 124         xt_unregister_match(&physdev_mt_reg);
 125 }
 126
 127 module_init(physdev_mt_init);
 128 module_exit(physdev_mt_exit);