LXR linux/net/netfilter/xt

   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
  18MODULE_LICENSE("GPL");
  19MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  20MODULE_DESCRIPTION("Xtables: Bridge physical device match");
  21MODULE_ALIAS("ipt_physdev");
  22MODULE_ALIAS("ip6t_physdev");
  23
  24
  25static bool
  26physdev_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
  84match_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
  96static 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("using --physdev-out and --physdev-is-out are only"
 111                        "supported in the FORWARD and POSTROUTING chains with"
 112                        "bridged traffic.\n");
 113                if (par->hook_mask & (1 << NF_INET_LOCAL_OUT))
 114                        return -EINVAL;
 115        }
 116        return 0;
 117}
 118
 119static struct xt_match physdev_mt_reg __read_mostly = {
 120        .name       = "physdev",
 121        .revision   = 0,
 122        .family     = NFPROTO_UNSPEC,
 123        .checkentry = physdev_mt_check,
 124        .match      = physdev_mt,
 125        .matchsize  = sizeof(struct xt_physdev_info),
 126        .me         = THIS_MODULE,
 127};
 128
 129static int __init physdev_mt_init(void)
 130{
 131        return xt_register_match(&physdev_mt_reg);
 132}
 133
 134static void __exit physdev_mt_exit(void)
 135{
 136        xt_unregister_match(&physdev_mt_reg);
 137}
 138
 139module_init(physdev_mt_init);
 140module_exit(physdev_mt_exit);
 141