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 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <linux/if_arp.h> |
| 12 | #include <linux/if_ether.h> |
| 13 | #include <linux/module.h> |
Jan Engelhardt | 18219d3 | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 14 | #include <linux/netfilter/x_tables.h> |
| 15 | #include <linux/netfilter_bridge/ebtables.h> |
| 16 | #include <linux/netfilter_bridge/ebt_arp.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 17 | |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 18 | static bool ebt_filter_arp(const struct sk_buff *skb, |
| 19 | const struct net_device *in, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | const struct net_device *out, const void *data, unsigned int datalen) |
| 21 | { |
Jan Engelhardt | abfdf1c | 2008-01-31 03:59:24 -0800 | [diff] [blame] | 22 | const struct ebt_arp_info *info = data; |
| 23 | const struct arphdr *ah; |
| 24 | struct arphdr _arph; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | |
| 26 | ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); |
| 27 | if (ah == NULL) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 28 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode != |
| 30 | ah->ar_op, EBT_ARP_OPCODE)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 31 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 32 | if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype != |
| 33 | ah->ar_hrd, EBT_ARP_HTYPE)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 34 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 35 | if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype != |
| 36 | ah->ar_pro, EBT_ARP_PTYPE)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 37 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | |
Bart De Schuymer | e011ff4 | 2007-11-05 20:59:47 -0800 | [diff] [blame] | 39 | if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP | EBT_ARP_GRAT)) { |
Jan Engelhardt | abfdf1c | 2008-01-31 03:59:24 -0800 | [diff] [blame] | 40 | const __be32 *sap, *dap; |
| 41 | __be32 saddr, daddr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 42 | |
Bart De Schuymer | c15bf6e | 2007-04-12 22:15:06 -0700 | [diff] [blame] | 43 | if (ah->ar_pln != sizeof(__be32) || ah->ar_pro != htons(ETH_P_IP)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 44 | return false; |
Bart De Schuymer | c15bf6e | 2007-04-12 22:15:06 -0700 | [diff] [blame] | 45 | sap = skb_header_pointer(skb, sizeof(struct arphdr) + |
| 46 | ah->ar_hln, sizeof(saddr), |
| 47 | &saddr); |
| 48 | if (sap == NULL) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 49 | return false; |
Bart De Schuymer | c15bf6e | 2007-04-12 22:15:06 -0700 | [diff] [blame] | 50 | dap = skb_header_pointer(skb, sizeof(struct arphdr) + |
| 51 | 2*ah->ar_hln+sizeof(saddr), |
| 52 | sizeof(daddr), &daddr); |
| 53 | if (dap == NULL) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 54 | return false; |
Bart De Schuymer | c15bf6e | 2007-04-12 22:15:06 -0700 | [diff] [blame] | 55 | if (info->bitmask & EBT_ARP_SRC_IP && |
| 56 | FWINV(info->saddr != (*sap & info->smsk), EBT_ARP_SRC_IP)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 57 | return false; |
Bart De Schuymer | c15bf6e | 2007-04-12 22:15:06 -0700 | [diff] [blame] | 58 | if (info->bitmask & EBT_ARP_DST_IP && |
| 59 | FWINV(info->daddr != (*dap & info->dmsk), EBT_ARP_DST_IP)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 60 | return false; |
Bart De Schuymer | c15bf6e | 2007-04-12 22:15:06 -0700 | [diff] [blame] | 61 | if (info->bitmask & EBT_ARP_GRAT && |
| 62 | FWINV(*dap != *sap, EBT_ARP_GRAT)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 63 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | } |
| 65 | |
| 66 | if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) { |
Jan Engelhardt | abfdf1c | 2008-01-31 03:59:24 -0800 | [diff] [blame] | 67 | const unsigned char *mp; |
| 68 | unsigned char _mac[ETH_ALEN]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | uint8_t verdict, i; |
| 70 | |
Bart De Schuymer | c15bf6e | 2007-04-12 22:15:06 -0700 | [diff] [blame] | 71 | if (ah->ar_hln != ETH_ALEN || ah->ar_hrd != htons(ARPHRD_ETHER)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 72 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 77 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 83 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 91 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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)) |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 97 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 98 | } |
| 99 | } |
| 100 | |
Jan Engelhardt | 8cc784e | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 101 | return true; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 102 | } |
| 103 | |
Jan Engelhardt | 19eda87 | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 104 | static bool ebt_arp_check(const char *tablename, unsigned int hookmask, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 105 | const struct ebt_entry *e, void *data, unsigned int datalen) |
| 106 | { |
Jan Engelhardt | abfdf1c | 2008-01-31 03:59:24 -0800 | [diff] [blame] | 107 | const struct ebt_arp_info *info = data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 109 | if ((e->ethproto != htons(ETH_P_ARP) && |
| 110 | e->ethproto != htons(ETH_P_RARP)) || |
| 111 | e->invflags & EBT_IPROTO) |
Jan Engelhardt | 19eda87 | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 112 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 113 | if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK) |
Jan Engelhardt | 19eda87 | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 114 | return false; |
| 115 | return true; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 116 | } |
| 117 | |
Jan Engelhardt | 30083c9 | 2008-01-31 04:00:59 -0800 | [diff] [blame] | 118 | static struct ebt_match filter_arp __read_mostly = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 119 | .name = EBT_ARP_MATCH, |
Jan Engelhardt | 001a18d | 2008-10-08 11:35:14 +0200 | [diff] [blame^] | 120 | .revision = 0, |
| 121 | .family = NFPROTO_BRIDGE, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 122 | .match = ebt_filter_arp, |
| 123 | .check = ebt_arp_check, |
Jan Engelhardt | 18219d3 | 2008-10-08 11:35:13 +0200 | [diff] [blame] | 124 | .matchsize = XT_ALIGN(sizeof(struct ebt_arp_info)), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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); |
Jan Engelhardt | f776c4c | 2008-01-31 04:00:30 -0800 | [diff] [blame] | 140 | MODULE_DESCRIPTION("Ebtables: ARP protocol packet match"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 141 | MODULE_LICENSE("GPL"); |