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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/netfilter_bridge/ebtables.h> #include <linux/netfilter_bridge/ebt_arp.h> #include <linux/if_arp.h> #include <linux/if_ether.h> #include <linux/module.h> static int ebt_filter_arp(const struct sk_buff *skb, const struct net_device *in, const struct net_device *out, const void *data, unsigned int datalen) { struct ebt_arp_info *info = (struct ebt_arp_info *)data; struct arphdr _arph, *ah; ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); if (ah == NULL) return EBT_NOMATCH; if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode != ah->ar_op, EBT_ARP_OPCODE)) return EBT_NOMATCH; if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype != ah->ar_hrd, EBT_ARP_HTYPE)) return EBT_NOMATCH; if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype != ah->ar_pro, EBT_ARP_PTYPE)) return EBT_NOMATCH; if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP)) { uint32_t _addr, *ap; /* IPv4 addresses are always 4 bytes */ if (ah->ar_pln != sizeof(uint32_t)) return EBT_NOMATCH; if (info->bitmask & EBT_ARP_SRC_IP) { ap = skb_header_pointer(skb, sizeof(struct arphdr) + ah->ar_hln, sizeof(_addr), &_addr); if (ap == NULL) return EBT_NOMATCH; if (FWINV(info->saddr != (*ap & info->smsk), EBT_ARP_SRC_IP)) return EBT_NOMATCH; } if (info->bitmask & EBT_ARP_DST_IP) { ap = skb_header_pointer(skb, sizeof(struct arphdr) + 2*ah->ar_hln+sizeof(uint32_t), sizeof(_addr), &_addr); if (ap == NULL) return EBT_NOMATCH; if (FWINV(info->daddr != (*ap & info->dmsk), EBT_ARP_DST_IP)) return EBT_NOMATCH; } } if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) { unsigned char _mac[ETH_ALEN], *mp; uint8_t verdict, i; /* MAC addresses are 6 bytes */ if (ah->ar_hln != ETH_ALEN) return EBT_NOMATCH; if (info->bitmask & EBT_ARP_SRC_MAC) { mp = skb_header_pointer(skb, sizeof(struct arphdr), sizeof(_mac), &_mac); if (mp == NULL) return EBT_NOMATCH; 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 EBT_NOMATCH; } 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 EBT_NOMATCH; 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 EBT_NOMATCH; } } return EBT_MATCH; } static int ebt_arp_check(const char *tablename, unsigned int hookmask, const struct ebt_entry *e, void *data, unsigned int datalen) { struct ebt_arp_info *info = (struct ebt_arp_info *)data; if (datalen != EBT_ALIGN(sizeof(struct ebt_arp_info))) return -EINVAL; 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 ebt_match filter_arp = { .name = EBT_ARP_MATCH, .match = ebt_filter_arp, .check = ebt_arp_check, .me = THIS_MODULE, }; static int __init init(void) { return ebt_register_match(&filter_arp); } static void __exit fini(void) { ebt_unregister_match(&filter_arp); } module_init(init); module_exit(fini); MODULE_LICENSE("GPL"); |