net/bridge/netfilter/ebt_802_3.c

   1 /*
   2  * 802_3
   3  *
   4  * Author:
   5  * Chris Vitale csv@bluetail.com
   6  *
   7  * May 2003
   8  *
   9  */
  10
  11 #include <linux/netfilter_bridge/ebtables.h>
  12 #include <linux/netfilter_bridge/ebt_802_3.h>
  13 #include <linux/module.h>
  14
  15 static int ebt_filter_802_3(const struct sk_buff *skb, const struct net_device *in,
  16    const struct net_device *out, const void *data, unsigned int datalen)
  17 {
  18         const struct ebt_802_3_info *info = data;
  19         const struct ebt_802_3_hdr *hdr = ebt_802_3_hdr(skb);
  20         __be16 type = hdr->llc.ui.ctrl & IS_UI ? hdr->llc.ui.type : hdr->llc.ni.type;
  21
  22         if (info->bitmask & EBT_802_3_SAP) {
  23                 if (FWINV(info->sap != hdr->llc.ui.ssap, EBT_802_3_SAP))
  24                                 return EBT_NOMATCH;
  25                 if (FWINV(info->sap != hdr->llc.ui.dsap, EBT_802_3_SAP))
  26                                 return EBT_NOMATCH;
  27         }
  28
  29         if (info->bitmask & EBT_802_3_TYPE) {
  30                 if (!(hdr->llc.ui.dsap == CHECK_TYPE && hdr->llc.ui.ssap == CHECK_TYPE))
  31                         return EBT_NOMATCH;
  32                 if (FWINV(info->type != type, EBT_802_3_TYPE))
  33                         return EBT_NOMATCH;
  34         }
  35
  36         return EBT_MATCH;
  37 }
  38
  39 static struct ebt_match filter_802_3;
  40 static int ebt_802_3_check(const char *tablename, unsigned int hookmask,
  41    const struct ebt_entry *e, void *data, unsigned int datalen)
  42 {
  43         const struct ebt_802_3_info *info = data;
  44
  45         if (datalen < sizeof(struct ebt_802_3_info))
  46                 return -EINVAL;
  47         if (info->bitmask & ~EBT_802_3_MASK || info->invflags & ~EBT_802_3_MASK)
  48                 return -EINVAL;
  49
  50         return 0;
  51 }
  52
  53 static struct ebt_match filter_802_3 __read_mostly = {
  54         .name           = EBT_802_3_MATCH,
  55         .match          = ebt_filter_802_3,
  56         .check          = ebt_802_3_check,
  57         .me             = THIS_MODULE,
  58 };
  59
  60 static int __init ebt_802_3_init(void)
  61 {
  62         return ebt_register_match(&filter_802_3);
  63 }
  64
  65 static void __exit ebt_802_3_fini(void)
  66 {
  67         ebt_unregister_match(&filter_802_3);
  68 }
  69
  70 module_init(ebt_802_3_init);
  71 module_exit(ebt_802_3_fini);
  72 MODULE_DESCRIPTION("Ebtables: DSAP/SSAP field and SNAP type matching");
  73 MODULE_LICENSE("GPL");