linux/net/netfilter/xt_physdev.c
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   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
  17MODULE_LICENSE("GPL");
  18MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  19MODULE_DESCRIPTION("Xtables: Bridge physical device match");
  20MODULE_ALIAS("ipt_physdev");
  21MODULE_ALIAS("ip6t_physdev");
  22
  23
  24static bool
  25physdev_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
  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        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
 107static 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
 117static int __init physdev_mt_init(void)
 118{
 119        return xt_register_match(&physdev_mt_reg);
 120}
 121
 122static void __exit physdev_mt_exit(void)
 123{
 124        xt_unregister_match(&physdev_mt_reg);
 125}
 126
 127module_init(physdev_mt_init);
 128module_exit(physdev_mt_exit);
 129
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