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        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->physoutdev ^ !(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
  76match_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
  86static int physdev_mt_check(const struct xt_mtchk_param *par)
  87{
  88        const struct xt_physdev_info *info = par->matchinfo;
  89
  90        br_netfilter_enable();
  91
  92        if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
  93            info->bitmask & ~XT_PHYSDEV_OP_MASK)
  94                return -EINVAL;
  95        if (info->bitmask & (XT_PHYSDEV_OP_OUT | XT_PHYSDEV_OP_ISOUT) &&
  96            (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
  97             info->invert & XT_PHYSDEV_OP_BRIDGED) &&
  98            par->hook_mask & ((1 << NF_INET_LOCAL_OUT) |
  99            (1 << NF_INET_FORWARD) | (1 << NF_INET_POST_ROUTING))) {
 100                pr_info("using --physdev-out and --physdev-is-out are only "
 101                        "supported in the FORWARD and POSTROUTING chains with "
 102                        "bridged traffic.\n");
 103                if (par->hook_mask & (1 << NF_INET_LOCAL_OUT))
 104                        return -EINVAL;
 105        }
 106        return 0;
 107}
 108
 109static struct xt_match physdev_mt_reg __read_mostly = {
 110        .name       = "physdev",
 111        .revision   = 0,
 112        .family     = NFPROTO_UNSPEC,
 113        .checkentry = physdev_mt_check,
 114        .match      = physdev_mt,
 115        .matchsize  = sizeof(struct xt_physdev_info),
 116        .me         = THIS_MODULE,
 117};
 118
 119static int __init physdev_mt_init(void)
 120{
 121        return xt_register_match(&physdev_mt_reg);
 122}
 123
 124static void __exit physdev_mt_exit(void)
 125{
 126        xt_unregister_match(&physdev_mt_reg);
 127}
 128
 129module_init(physdev_mt_init);
 130module_exit(physdev_mt_exit);
 131