Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * ebt_arpreply |
| 3 | * |
| 4 | * Authors: |
| 5 | * Grzegorz Borowiak <grzes@gnu.univ.gda.pl> |
| 6 | * Bart De Schuymer <bdschuym@pandora.be> |
| 7 | * |
| 8 | * August, 2003 |
| 9 | * |
| 10 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <linux/if_arp.h> |
| 12 | #include <net/arp.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_arpreply.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 17 | |
Jan Engelhardt | 2d06d4a | 2008-10-08 11:35:15 +0200 | [diff] [blame] | 18 | static unsigned int |
Jan Engelhardt | 4b560b4 | 2009-07-05 19:43:26 +0200 | [diff] [blame] | 19 | ebt_arpreply_tg(struct sk_buff *skb, const struct xt_action_param *par) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | { |
Jan Engelhardt | 7eb3558 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 21 | const struct ebt_arpreply_info *info = par->targinfo; |
Jan Engelhardt | abfdf1c | 2008-01-31 03:59:24 -0800 | [diff] [blame] | 22 | const __be32 *siptr, *diptr; |
| 23 | __be32 _sip, _dip; |
| 24 | const struct arphdr *ap; |
| 25 | struct arphdr _ah; |
| 26 | const unsigned char *shp; |
| 27 | unsigned char _sha[ETH_ALEN]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 28 | |
| 29 | ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah); |
| 30 | if (ap == NULL) |
| 31 | return EBT_DROP; |
| 32 | |
| 33 | if (ap->ar_op != htons(ARPOP_REQUEST) || |
| 34 | ap->ar_hln != ETH_ALEN || |
| 35 | ap->ar_pro != htons(ETH_P_IP) || |
| 36 | ap->ar_pln != 4) |
| 37 | return EBT_CONTINUE; |
| 38 | |
| 39 | shp = skb_header_pointer(skb, sizeof(_ah), ETH_ALEN, &_sha); |
| 40 | if (shp == NULL) |
| 41 | return EBT_DROP; |
| 42 | |
| 43 | siptr = skb_header_pointer(skb, sizeof(_ah) + ETH_ALEN, |
| 44 | sizeof(_sip), &_sip); |
| 45 | if (siptr == NULL) |
| 46 | return EBT_DROP; |
| 47 | |
| 48 | diptr = skb_header_pointer(skb, |
| 49 | sizeof(_ah) + 2 * ETH_ALEN + sizeof(_sip), |
| 50 | sizeof(_dip), &_dip); |
| 51 | if (diptr == NULL) |
| 52 | return EBT_DROP; |
| 53 | |
Jan Engelhardt | 7eb3558 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 54 | arp_send(ARPOP_REPLY, ETH_P_ARP, *siptr, (struct net_device *)par->in, |
YOSHIFUJI Hideaki | 9d6f229 | 2007-02-09 23:24:35 +0900 | [diff] [blame] | 55 | *diptr, shp, info->mac, shp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 56 | |
| 57 | return info->target; |
| 58 | } |
| 59 | |
Jan Engelhardt | 135367b | 2010-03-19 17:16:42 +0100 | [diff] [blame] | 60 | static int ebt_arpreply_tg_check(const struct xt_tgchk_param *par) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 61 | { |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 62 | const struct ebt_arpreply_info *info = par->targinfo; |
| 63 | const struct ebt_entry *e = par->entryinfo; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 65 | if (BASE_CHAIN && info->target == EBT_RETURN) |
Jan Engelhardt | d6b00a5 | 2010-03-25 16:34:45 +0100 | [diff] [blame] | 66 | return -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 67 | if (e->ethproto != htons(ETH_P_ARP) || |
| 68 | e->invflags & EBT_IPROTO) |
Jan Engelhardt | d6b00a5 | 2010-03-25 16:34:45 +0100 | [diff] [blame] | 69 | return -EINVAL; |
| 70 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 71 | } |
| 72 | |
Jan Engelhardt | 043ef46 | 2008-10-08 11:35:15 +0200 | [diff] [blame] | 73 | static struct xt_target ebt_arpreply_tg_reg __read_mostly = { |
| 74 | .name = "arpreply", |
Jan Engelhardt | 001a18d | 2008-10-08 11:35:14 +0200 | [diff] [blame] | 75 | .revision = 0, |
| 76 | .family = NFPROTO_BRIDGE, |
Jan Engelhardt | f2ff525 | 2008-10-08 11:35:15 +0200 | [diff] [blame] | 77 | .table = "nat", |
| 78 | .hooks = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING), |
Jan Engelhardt | 2d06d4a | 2008-10-08 11:35:15 +0200 | [diff] [blame] | 79 | .target = ebt_arpreply_tg, |
| 80 | .checkentry = ebt_arpreply_tg_check, |
Florian Westphal | fc0e3df | 2010-02-15 18:16:26 +0100 | [diff] [blame] | 81 | .targetsize = sizeof(struct ebt_arpreply_info), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 82 | .me = THIS_MODULE, |
| 83 | }; |
| 84 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 85 | static int __init ebt_arpreply_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | { |
Jan Engelhardt | 043ef46 | 2008-10-08 11:35:15 +0200 | [diff] [blame] | 87 | return xt_register_target(&ebt_arpreply_tg_reg); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | } |
| 89 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 90 | static void __exit ebt_arpreply_fini(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 91 | { |
Jan Engelhardt | 043ef46 | 2008-10-08 11:35:15 +0200 | [diff] [blame] | 92 | xt_unregister_target(&ebt_arpreply_tg_reg); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 93 | } |
| 94 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 95 | module_init(ebt_arpreply_init); |
| 96 | module_exit(ebt_arpreply_fini); |
Jan Engelhardt | f776c4c | 2008-01-31 04:00:30 -0800 | [diff] [blame] | 97 | MODULE_DESCRIPTION("Ebtables: ARP reply target"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 98 | MODULE_LICENSE("GPL"); |