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