LXR linux/net/netfilter/xt

   1// SPDX-License-Identifier: GPL-2.0-only
   2/* Kernel module to match the bridge port in and
   3 * out device for IP packets coming into contact with a bridge. */
   4
   5/* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be>
   6 */
   7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   8
   9#include <linux/if.h>
  10#include <linux/module.h>
  11#include <linux/skbuff.h>
  12#include <linux/netfilter_bridge.h>
  13#include <linux/netfilter/x_tables.h>
  14#include <uapi/linux/netfilter/xt_physdev.h>
  15
  16MODULE_LICENSE("GPL");
  17MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  18MODULE_DESCRIPTION("Xtables: Bridge physical device match");
  19MODULE_ALIAS("ipt_physdev");
  20MODULE_ALIAS("ip6t_physdev");
  21
  22
  23static bool
  24physdev_mt(const struct sk_buff *skb, struct xt_action_param *par)
  25{
  26        const struct xt_physdev_info *info = par->matchinfo;
  27        const struct net_device *physdev;
  28        unsigned long ret;
  29        const char *indev, *outdev;
  30
  31        /* Not a bridged IP packet or no info available yet:
  32         * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
  33         * the destination device will be a bridge. */
  34        if (!nf_bridge_info_exists(skb)) {
  35                /* Return MATCH if the invert flags of the used options are on */
  36                if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  37                    !(info->invert & XT_PHYSDEV_OP_BRIDGED))
  38                        return false;
  39                if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
  40                    !(info->invert & XT_PHYSDEV_OP_ISIN))
  41                        return false;
  42                if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
  43                    !(info->invert & XT_PHYSDEV_OP_ISOUT))
  44                        return false;
  45                if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
  46                    !(info->invert & XT_PHYSDEV_OP_IN))
  47                        return false;
  48                if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
  49                    !(info->invert & XT_PHYSDEV_OP_OUT))
  50                        return false;
  51                return true;
  52        }
  53
  54        physdev = nf_bridge_get_physoutdev(skb);
  55        outdev = physdev ? physdev->name : NULL;
  56
  57        /* This only makes sense in the FORWARD and POSTROUTING chains */
  58        if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
  59            (!!outdev ^ !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
  60                return false;
  61
  62        physdev = nf_bridge_get_physindev(skb);
  63        indev = physdev ? physdev->name : NULL;
  64
  65        if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
  66            (!indev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
  67            (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
  68            (!outdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
  69                return false;
  70
  71        if (!(info->bitmask & XT_PHYSDEV_OP_IN))
  72                goto match_outdev;
  73
  74        if (indev) {
  75                ret = ifname_compare_aligned(indev, info->physindev,
  76                                             info->in_mask);
  77
  78                if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN))
  79                        return false;
  80        }
  81
  82match_outdev:
  83        if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
  84                return true;
  85
  86        if (!outdev)
  87                return false;
  88
  89        ret = ifname_compare_aligned(outdev, info->physoutdev, info->out_mask);
  90
  91        return (!!ret ^ !(info->invert & XT_PHYSDEV_OP_OUT));
  92}
  93
  94static int physdev_mt_check(const struct xt_mtchk_param *par)
  95{
  96        const struct xt_physdev_info *info = par->matchinfo;
  97        static bool brnf_probed __read_mostly;
  98
  99        if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
 100            info->bitmask & ~XT_PHYSDEV_OP_MASK)
 101                return -EINVAL;
 102        if (info->bitmask & (XT_PHYSDEV_OP_OUT | XT_PHYSDEV_OP_ISOUT) &&
 103            (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
 104             info->invert & XT_PHYSDEV_OP_BRIDGED) &&
 105            par->hook_mask & (1 << NF_INET_LOCAL_OUT)) {
 106                pr_info_ratelimited("--physdev-out and --physdev-is-out only supported in the FORWARD and POSTROUTING chains with bridged traffic\n");
 107                return -EINVAL;
 108        }
 109
 110        if (!brnf_probed) {
 111                brnf_probed = true;
 112                request_module("br_netfilter");
 113        }
 114
 115        return 0;
 116}
 117
 118static struct xt_match physdev_mt_reg __read_mostly = {
 119        .name       = "physdev",
 120        .revision   = 0,
 121        .family     = NFPROTO_UNSPEC,
 122        .checkentry = physdev_mt_check,
 123        .match      = physdev_mt,
 124        .matchsize  = sizeof(struct xt_physdev_info),
 125        .me         = THIS_MODULE,
 126};
 127
 128static int __init physdev_mt_init(void)
 129{
 130        return xt_register_match(&physdev_mt_reg);
 131}
 132
 133static void __exit physdev_mt_exit(void)
 134{
 135        xt_unregister_match(&physdev_mt_reg);
 136}
 137
 138module_init(physdev_mt_init);
 139module_exit(physdev_mt_exit);
 140