root/net/bridge/netfilter/ebt_802_3.c

DEFINITIONS

1. ebt_802_3_mt
2. ebt_802_3_mt_check
3. ebt_802_3_init
4. ebt_802_3_fini

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * 802_3
   4  *
   5  * Author:
   6  * Chris Vitale csv@bluetail.com
   7  *
   8  * May 2003
   9  *
  10  */
  11 #include <linux/module.h>
  12 #include <linux/netfilter/x_tables.h>
  13 #include <linux/netfilter_bridge/ebtables.h>
  14 #include <linux/skbuff.h>
  15 #include <uapi/linux/netfilter_bridge/ebt_802_3.h>
  16 
  17 static struct ebt_802_3_hdr *ebt_802_3_hdr(const struct sk_buff *skb)
  18 {
  19         return (struct ebt_802_3_hdr *)skb_mac_header(skb);
  20 }
  21 
  22 static bool
  23 ebt_802_3_mt(const struct sk_buff *skb, struct xt_action_param *par)
  24 {
  25         const struct ebt_802_3_info *info = par->matchinfo;
  26         const struct ebt_802_3_hdr *hdr = ebt_802_3_hdr(skb);
  27         __be16 type = hdr->llc.ui.ctrl & IS_UI ? hdr->llc.ui.type : hdr->llc.ni.type;
  28 
  29         if (info->bitmask & EBT_802_3_SAP) {
  30                 if (NF_INVF(info, EBT_802_3_SAP, info->sap != hdr->llc.ui.ssap))
  31                         return false;
  32                 if (NF_INVF(info, EBT_802_3_SAP, info->sap != hdr->llc.ui.dsap))
  33                         return false;
  34         }
  35 
  36         if (info->bitmask & EBT_802_3_TYPE) {
  37                 if (!(hdr->llc.ui.dsap == CHECK_TYPE && hdr->llc.ui.ssap == CHECK_TYPE))
  38                         return false;
  39                 if (NF_INVF(info, EBT_802_3_TYPE, info->type != type))
  40                         return false;
  41         }
  42 
  43         return true;
  44 }
  45 
  46 static int ebt_802_3_mt_check(const struct xt_mtchk_param *par)
  47 {
  48         const struct ebt_802_3_info *info = par->matchinfo;
  49 
  50         if (info->bitmask & ~EBT_802_3_MASK || info->invflags & ~EBT_802_3_MASK)
  51                 return -EINVAL;
  52 
  53         return 0;
  54 }
  55 
  56 static struct xt_match ebt_802_3_mt_reg __read_mostly = {
  57         .name           = "802_3",
  58         .revision       = 0,
  59         .family         = NFPROTO_BRIDGE,
  60         .match          = ebt_802_3_mt,
  61         .checkentry     = ebt_802_3_mt_check,
  62         .matchsize      = sizeof(struct ebt_802_3_info),
  63         .me             = THIS_MODULE,
  64 };
  65 
  66 static int __init ebt_802_3_init(void)
  67 {
  68         return xt_register_match(&ebt_802_3_mt_reg);
  69 }
  70 
  71 static void __exit ebt_802_3_fini(void)
  72 {
  73         xt_unregister_match(&ebt_802_3_mt_reg);
  74 }
  75 
  76 module_init(ebt_802_3_init);
  77 module_exit(ebt_802_3_fini);
  78 MODULE_DESCRIPTION("Ebtables: DSAP/SSAP field and SNAP type matching");
  79 MODULE_LICENSE("GPL");