net/netfilter/xt_physdev.c

   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
  16 MODULE_LICENSE("GPL");
  17 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
  18 MODULE_DESCRIPTION("Xtables: Bridge physical device match");
  19 MODULE_ALIAS("ipt_physdev");
  20 MODULE_ALIAS("ip6t_physdev");
  21
  22
  23 static bool
  24 physdev_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
  82 match_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
  94 static 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
 118 static 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
 128 static int __init physdev_mt_init(void)
 129 {
 130         return xt_register_match(&physdev_mt_reg);
 131 }
 132
 133 static void __exit physdev_mt_exit(void)
 134 {
 135         xt_unregister_match(&physdev_mt_reg);
 136 }
 137
 138 module_init(physdev_mt_init);
 139 module_exit(physdev_mt_exit);