Commit | Line | Data |
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1da177e4 LT |
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 | */ | |
1da177e4 LT |
11 | #include <linux/if_arp.h> |
12 | #include <net/arp.h> | |
13 | #include <linux/module.h> | |
18219d3f JE |
14 | #include <linux/netfilter/x_tables.h> |
15 | #include <linux/netfilter_bridge/ebtables.h> | |
16 | #include <linux/netfilter_bridge/ebt_arpreply.h> | |
1da177e4 | 17 | |
2d06d4a5 | 18 | static unsigned int |
4b560b44 | 19 | ebt_arpreply_tg(struct sk_buff *skb, const struct xt_action_param *par) |
1da177e4 | 20 | { |
7eb35586 | 21 | const struct ebt_arpreply_info *info = par->targinfo; |
abfdf1c4 JE |
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]; | |
1da177e4 LT |
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 | ||
7eb35586 | 54 | arp_send(ARPOP_REPLY, ETH_P_ARP, *siptr, (struct net_device *)par->in, |
9d6f229f | 55 | *diptr, shp, info->mac, shp); |
1da177e4 LT |
56 | |
57 | return info->target; | |
58 | } | |
59 | ||
135367b8 | 60 | static int ebt_arpreply_tg_check(const struct xt_tgchk_param *par) |
1da177e4 | 61 | { |
af5d6dc2 JE |
62 | const struct ebt_arpreply_info *info = par->targinfo; |
63 | const struct ebt_entry *e = par->entryinfo; | |
1da177e4 | 64 | |
1da177e4 | 65 | if (BASE_CHAIN && info->target == EBT_RETURN) |
d6b00a53 | 66 | return -EINVAL; |
1da177e4 LT |
67 | if (e->ethproto != htons(ETH_P_ARP) || |
68 | e->invflags & EBT_IPROTO) | |
d6b00a53 JE |
69 | return -EINVAL; |
70 | return 0; | |
1da177e4 LT |
71 | } |
72 | ||
043ef46c JE |
73 | static struct xt_target ebt_arpreply_tg_reg __read_mostly = { |
74 | .name = "arpreply", | |
001a18d3 JE |
75 | .revision = 0, |
76 | .family = NFPROTO_BRIDGE, | |
f2ff525c JE |
77 | .table = "nat", |
78 | .hooks = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING), | |
2d06d4a5 JE |
79 | .target = ebt_arpreply_tg, |
80 | .checkentry = ebt_arpreply_tg_check, | |
fc0e3df4 | 81 | .targetsize = sizeof(struct ebt_arpreply_info), |
1da177e4 LT |
82 | .me = THIS_MODULE, |
83 | }; | |
84 | ||
65b4b4e8 | 85 | static int __init ebt_arpreply_init(void) |
1da177e4 | 86 | { |
043ef46c | 87 | return xt_register_target(&ebt_arpreply_tg_reg); |
1da177e4 LT |
88 | } |
89 | ||
65b4b4e8 | 90 | static void __exit ebt_arpreply_fini(void) |
1da177e4 | 91 | { |
043ef46c | 92 | xt_unregister_target(&ebt_arpreply_tg_reg); |
1da177e4 LT |
93 | } |
94 | ||
65b4b4e8 AM |
95 | module_init(ebt_arpreply_init); |
96 | module_exit(ebt_arpreply_fini); | |
f776c4cd | 97 | MODULE_DESCRIPTION("Ebtables: ARP reply target"); |
1da177e4 | 98 | MODULE_LICENSE("GPL"); |