Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * ebt_arp |
| 3 | * |
| 4 | * Authors: |
| 5 | * Bart De Schuymer <bdschuym@pandora.be> |
| 6 | * Tim Gardner <timg@tpi.com> |
| 7 | * |
| 8 | * April, 2002 |
| 9 | * |
| 10 | */ |
| 11 | |
| 12 | #include <linux/netfilter_bridge/ebtables.h> |
| 13 | #include <linux/netfilter_bridge/ebt_arp.h> |
| 14 | #include <linux/if_arp.h> |
| 15 | #include <linux/if_ether.h> |
| 16 | #include <linux/module.h> |
| 17 | |
| 18 | static int ebt_filter_arp(const struct sk_buff *skb, const struct net_device *in, |
| 19 | const struct net_device *out, const void *data, unsigned int datalen) |
| 20 | { |
| 21 | struct ebt_arp_info *info = (struct ebt_arp_info *)data; |
| 22 | struct arphdr _arph, *ah; |
| 23 | |
| 24 | ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); |
| 25 | if (ah == NULL) |
| 26 | return EBT_NOMATCH; |
| 27 | if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode != |
| 28 | ah->ar_op, EBT_ARP_OPCODE)) |
| 29 | return EBT_NOMATCH; |
| 30 | if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype != |
| 31 | ah->ar_hrd, EBT_ARP_HTYPE)) |
| 32 | return EBT_NOMATCH; |
| 33 | if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype != |
| 34 | ah->ar_pro, EBT_ARP_PTYPE)) |
| 35 | return EBT_NOMATCH; |
| 36 | |
| 37 | if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP)) { |
| 38 | uint32_t _addr, *ap; |
| 39 | |
| 40 | /* IPv4 addresses are always 4 bytes */ |
| 41 | if (ah->ar_pln != sizeof(uint32_t)) |
| 42 | return EBT_NOMATCH; |
| 43 | if (info->bitmask & EBT_ARP_SRC_IP) { |
| 44 | ap = skb_header_pointer(skb, sizeof(struct arphdr) + |
| 45 | ah->ar_hln, sizeof(_addr), |
| 46 | &_addr); |
| 47 | if (ap == NULL) |
| 48 | return EBT_NOMATCH; |
| 49 | if (FWINV(info->saddr != (*ap & info->smsk), |
| 50 | EBT_ARP_SRC_IP)) |
| 51 | return EBT_NOMATCH; |
| 52 | } |
| 53 | |
| 54 | if (info->bitmask & EBT_ARP_DST_IP) { |
| 55 | ap = skb_header_pointer(skb, sizeof(struct arphdr) + |
| 56 | 2*ah->ar_hln+sizeof(uint32_t), |
| 57 | sizeof(_addr), &_addr); |
| 58 | if (ap == NULL) |
| 59 | return EBT_NOMATCH; |
| 60 | if (FWINV(info->daddr != (*ap & info->dmsk), |
| 61 | EBT_ARP_DST_IP)) |
| 62 | return EBT_NOMATCH; |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) { |
| 67 | unsigned char _mac[ETH_ALEN], *mp; |
| 68 | uint8_t verdict, i; |
| 69 | |
| 70 | /* MAC addresses are 6 bytes */ |
| 71 | if (ah->ar_hln != ETH_ALEN) |
| 72 | return EBT_NOMATCH; |
| 73 | if (info->bitmask & EBT_ARP_SRC_MAC) { |
| 74 | mp = skb_header_pointer(skb, sizeof(struct arphdr), |
| 75 | sizeof(_mac), &_mac); |
| 76 | if (mp == NULL) |
| 77 | return EBT_NOMATCH; |
| 78 | verdict = 0; |
| 79 | for (i = 0; i < 6; i++) |
| 80 | verdict |= (mp[i] ^ info->smaddr[i]) & |
| 81 | info->smmsk[i]; |
| 82 | if (FWINV(verdict != 0, EBT_ARP_SRC_MAC)) |
| 83 | return EBT_NOMATCH; |
| 84 | } |
| 85 | |
| 86 | if (info->bitmask & EBT_ARP_DST_MAC) { |
| 87 | mp = skb_header_pointer(skb, sizeof(struct arphdr) + |
| 88 | ah->ar_hln + ah->ar_pln, |
| 89 | sizeof(_mac), &_mac); |
| 90 | if (mp == NULL) |
| 91 | return EBT_NOMATCH; |
| 92 | verdict = 0; |
| 93 | for (i = 0; i < 6; i++) |
| 94 | verdict |= (mp[i] ^ info->dmaddr[i]) & |
| 95 | info->dmmsk[i]; |
| 96 | if (FWINV(verdict != 0, EBT_ARP_DST_MAC)) |
| 97 | return EBT_NOMATCH; |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | return EBT_MATCH; |
| 102 | } |
| 103 | |
| 104 | static int ebt_arp_check(const char *tablename, unsigned int hookmask, |
| 105 | const struct ebt_entry *e, void *data, unsigned int datalen) |
| 106 | { |
| 107 | struct ebt_arp_info *info = (struct ebt_arp_info *)data; |
| 108 | |
| 109 | if (datalen != EBT_ALIGN(sizeof(struct ebt_arp_info))) |
| 110 | return -EINVAL; |
| 111 | if ((e->ethproto != htons(ETH_P_ARP) && |
| 112 | e->ethproto != htons(ETH_P_RARP)) || |
| 113 | e->invflags & EBT_IPROTO) |
| 114 | return -EINVAL; |
| 115 | if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK) |
| 116 | return -EINVAL; |
| 117 | return 0; |
| 118 | } |
| 119 | |
| 120 | static struct ebt_match filter_arp = |
| 121 | { |
| 122 | .name = EBT_ARP_MATCH, |
| 123 | .match = ebt_filter_arp, |
| 124 | .check = ebt_arp_check, |
| 125 | .me = THIS_MODULE, |
| 126 | }; |
| 127 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame^] | 128 | static int __init ebt_arp_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | { |
| 130 | return ebt_register_match(&filter_arp); |
| 131 | } |
| 132 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame^] | 133 | static void __exit ebt_arp_fini(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | { |
| 135 | ebt_unregister_match(&filter_arp); |
| 136 | } |
| 137 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame^] | 138 | module_init(ebt_arp_init); |
| 139 | module_exit(ebt_arp_fini); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | MODULE_LICENSE("GPL"); |