ebt_arp.rar_V2

/* * ebt_arp * * Authors: * Bart De Schuymer <bdschuym@pandora.be> * Tim Gardner <timg@tpi.com> * * April, 2002 * */ #include <linux/if_arp.h> #include <linux/if_ether.h> #include <linux/module.h> #include <linux/netfilter/x_tables.h> #include <linux/netfilter_bridge/ebtables.h> #include <linux/netfilter_bridge/ebt_arp.h> static bool ebt_arp_mt(const struct sk_buff *skb, struct xt_action_param *par) { const struct ebt_arp_info *info = par->matchinfo; const struct arphdr *ah; struct arphdr _arph; ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); if (ah == NULL) return false; if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode != ah->ar_op, EBT_ARP_OPCODE)) return false; if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype != ah->ar_hrd, EBT_ARP_HTYPE)) return false; if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype != ah->ar_pro, EBT_ARP_PTYPE)) return false; if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP | EBT_ARP_GRAT)) { const __be32 *sap, *dap; __be32 saddr, daddr; if (ah->ar_pln != sizeof(__be32) || ah->ar_pro != htons(ETH_P_IP)) return false; sap = skb_header_pointer(skb, sizeof(struct arphdr) + ah->ar_hln, sizeof(saddr), &saddr); if (sap == NULL) return false; dap = skb_header_pointer(skb, sizeof(struct arphdr) + 2*ah->ar_hln+sizeof(saddr), sizeof(daddr), &daddr); if (dap == NULL) return false; if (info->bitmask & EBT_ARP_SRC_IP && FWINV(info->saddr != (*sap & info->smsk), EBT_ARP_SRC_IP)) return false; if (info->bitmask & EBT_ARP_DST_IP && FWINV(info->daddr != (*dap & info->dmsk), EBT_ARP_DST_IP)) return false; if (info->bitmask & EBT_ARP_GRAT && FWINV(*dap != *sap, EBT_ARP_GRAT)) return false; } if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) { const unsigned char *mp; unsigned char _mac[ETH_ALEN]; uint8_t verdict, i; if (ah->ar_hln != ETH_ALEN || ah->ar_hrd != htons(ARPHRD_ETHER)) return false; if (info->bitmask & EBT_ARP_SRC_MAC) { mp = skb_header_pointer(skb, sizeof(struct arphdr), sizeof(_mac), &_mac); if (mp == NULL) return false; verdict = 0; for (i = 0; i < 6; i++) verdict |= (mp[i] ^ info->smaddr[i]) & info->smmsk[i]; if (FWINV(verdict != 0, EBT_ARP_SRC_MAC)) return false; } if (info->bitmask & EBT_ARP_DST_MAC) { mp = skb_header_pointer(skb, sizeof(struct arphdr) + ah->ar_hln + ah->ar_pln, sizeof(_mac), &_mac); if (mp == NULL) return false; verdict = 0; for (i = 0; i < 6; i++) verdict |= (mp[i] ^ info->dmaddr[i]) & info->dmmsk[i]; if (FWINV(verdict != 0, EBT_ARP_DST_MAC)) return false; } } return true; } static int ebt_arp_mt_check(const struct xt_mtchk_param *par) { const struct ebt_arp_info *info = par->matchinfo; const struct ebt_entry *e = par->entryinfo; if ((e->ethproto != htons(ETH_P_ARP) && e->ethproto != htons(ETH_P_RARP)) || e->invflags & EBT_IPROTO) return -EINVAL; if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK) return -EINVAL; return 0; } static struct xt_match ebt_arp_mt_reg __read_mostly = { .name = "arp", .revision = 0, .family = NFPROTO_BRIDGE, .match = ebt_arp_mt, .checkentry = ebt_arp_mt_check, .matchsize = sizeof(struct ebt_arp_info), .me = THIS_MODULE, }; static int __init ebt_arp_init(void) { return xt_register_match(&ebt_arp_mt_reg); } static void __exit ebt_arp_fini(void) { xt_unregister_match(&ebt_arp_mt_reg); } module_init(ebt_arp_init); module_exit(ebt_arp_fini); MODULE_DESCRIPTION("Ebtables: ARP protocol packet match"); MODULE_LICENSE("GPL");