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 #include <net/netfilter/br_netfilter.h>
  17
  18 MODULE_LICENSE("GPL");
  19 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  20 MODULE_DESCRIPTION("Xtables: Bridge physical device match");
  21 MODULE_ALIAS("ipt_physdev");
  22 MODULE_ALIAS("ip6t_physdev");
  23
  24
  25 static bool
  26 physdev_mt(const struct sk_buff *skb, struct xt_action_param *par)
  27 {
  28         const struct xt_physdev_info *info = par->matchinfo;
  29         const struct net_device *physdev;
  30         unsigned long ret;
  31         const char *indev, *outdev;
  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 (!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         physdev = nf_bridge_get_physoutdev(skb);
  57         outdev = physdev ? physdev->name : NULL;
  58
  59         /* This only makes sense in the FORWARD and POSTROUTING chains */
  60         if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  61             (!!outdev ^ !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
  62                 return false;
  63
  64         physdev = nf_bridge_get_physindev(skb);
  65         indev = physdev ? physdev->name : NULL;
  66
  67         if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
  68             (!indev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
  69             (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
  70             (!outdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
  71                 return false;
  72
  73         if (!(info->bitmask & XT_PHYSDEV_OP_IN))
  74                 goto match_outdev;
  75
  76         if (indev) {
  77                 ret = ifname_compare_aligned(indev, info->physindev,
  78                                              info->in_mask);
  79
  80                 if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN))
  81                         return false;
  82         }
  83
  84 match_outdev:
  85         if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  86                 return true;
  87
  88         if (!outdev)
  89                 return false;
  90
  91         ret = ifname_compare_aligned(outdev, info->physoutdev, info->out_mask);
  92
  93         return (!!ret ^ !(info->invert & XT_PHYSDEV_OP_OUT));
  94 }
  95
  96 static int physdev_mt_check(const struct xt_mtchk_param *par)
  97 {
  98         const struct xt_physdev_info *info = par->matchinfo;
  99
 100         br_netfilter_enable();
 101
 102         if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
 103             info->bitmask & ~XT_PHYSDEV_OP_MASK)
 104                 return -EINVAL;
 105         if (info->bitmask & (XT_PHYSDEV_OP_OUT | XT_PHYSDEV_OP_ISOUT) &&
 106             (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
 107              info->invert & XT_PHYSDEV_OP_BRIDGED) &&
 108             par->hook_mask & ((1 << NF_INET_LOCAL_OUT) |
 109             (1 << NF_INET_FORWARD) | (1 << NF_INET_POST_ROUTING))) {
 110                 pr_info_ratelimited("--physdev-out and --physdev-is-out only supported in the FORWARD and POSTROUTING chains with bridged traffic\n");
 111                 if (par->hook_mask & (1 << NF_INET_LOCAL_OUT))
 112                         return -EINVAL;
 113         }
 114         return 0;
 115 }
 116
 117 static struct xt_match physdev_mt_reg __read_mostly = {
 118         .name       = "physdev",
 119         .revision   = 0,
 120         .family     = NFPROTO_UNSPEC,
 121         .checkentry = physdev_mt_check,
 122         .match      = physdev_mt,
 123         .matchsize  = sizeof(struct xt_physdev_info),
 124         .me         = THIS_MODULE,
 125 };
 126
 127 static int __init physdev_mt_init(void)
 128 {
 129         return xt_register_match(&physdev_mt_reg);
 130 }
 131
 132 static void __exit physdev_mt_exit(void)
 133 {
 134         xt_unregister_match(&physdev_mt_reg);
 135 }
 136
 137 module_init(physdev_mt_init);
 138 module_exit(physdev_mt_exit);