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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | /* * 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, const struct xt_match_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 bool 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 false; if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK) return false; return true; } 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 = XT_ALIGN(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"); |