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