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"); 80