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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 | */ | |
11 | ||
12 | #include <linux/netfilter_bridge/ebtables.h> | |
13 | #include <linux/netfilter_bridge/ebt_arpreply.h> | |
14 | #include <linux/if_arp.h> | |
15 | #include <net/arp.h> | |
16 | #include <linux/module.h> | |
17 | ||
18 | static int ebt_target_reply(struct sk_buff **pskb, unsigned int hooknr, | |
19 | const struct net_device *in, const struct net_device *out, | |
20 | const void *data, unsigned int datalen) | |
21 | { | |
22 | struct ebt_arpreply_info *info = (struct ebt_arpreply_info *)data; | |
23 | u32 _sip, *siptr, _dip, *diptr; | |
24 | struct arphdr _ah, *ap; | |
25 | unsigned char _sha[ETH_ALEN], *shp; | |
26 | struct sk_buff *skb = *pskb; | |
27 | ||
28 | ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah); | |
29 | if (ap == NULL) | |
30 | return EBT_DROP; | |
31 | ||
32 | if (ap->ar_op != htons(ARPOP_REQUEST) || | |
33 | ap->ar_hln != ETH_ALEN || | |
34 | ap->ar_pro != htons(ETH_P_IP) || | |
35 | ap->ar_pln != 4) | |
36 | return EBT_CONTINUE; | |
37 | ||
38 | shp = skb_header_pointer(skb, sizeof(_ah), ETH_ALEN, &_sha); | |
39 | if (shp == NULL) | |
40 | return EBT_DROP; | |
41 | ||
42 | siptr = skb_header_pointer(skb, sizeof(_ah) + ETH_ALEN, | |
43 | sizeof(_sip), &_sip); | |
44 | if (siptr == NULL) | |
45 | return EBT_DROP; | |
46 | ||
47 | diptr = skb_header_pointer(skb, | |
48 | sizeof(_ah) + 2 * ETH_ALEN + sizeof(_sip), | |
49 | sizeof(_dip), &_dip); | |
50 | if (diptr == NULL) | |
51 | return EBT_DROP; | |
52 | ||
53 | arp_send(ARPOP_REPLY, ETH_P_ARP, *siptr, (struct net_device *)in, | |
54 | *diptr, shp, info->mac, shp); | |
55 | ||
56 | return info->target; | |
57 | } | |
58 | ||
59 | static int ebt_target_reply_check(const char *tablename, unsigned int hookmask, | |
60 | const struct ebt_entry *e, void *data, unsigned int datalen) | |
61 | { | |
62 | struct ebt_arpreply_info *info = (struct ebt_arpreply_info *)data; | |
63 | ||
64 | if (datalen != EBT_ALIGN(sizeof(struct ebt_arpreply_info))) | |
65 | return -EINVAL; | |
66 | if (BASE_CHAIN && info->target == EBT_RETURN) | |
67 | return -EINVAL; | |
68 | if (e->ethproto != htons(ETH_P_ARP) || | |
69 | e->invflags & EBT_IPROTO) | |
70 | return -EINVAL; | |
71 | CLEAR_BASE_CHAIN_BIT; | |
72 | if (strcmp(tablename, "nat") || hookmask & ~(1 << NF_BR_PRE_ROUTING)) | |
73 | return -EINVAL; | |
74 | return 0; | |
75 | } | |
76 | ||
77 | static struct ebt_target reply_target = | |
78 | { | |
79 | .name = EBT_ARPREPLY_TARGET, | |
80 | .target = ebt_target_reply, | |
81 | .check = ebt_target_reply_check, | |
82 | .me = THIS_MODULE, | |
83 | }; | |
84 | ||
65b4b4e8 | 85 | static int __init ebt_arpreply_init(void) |
1da177e4 LT |
86 | { |
87 | return ebt_register_target(&reply_target); | |
88 | } | |
89 | ||
65b4b4e8 | 90 | static void __exit ebt_arpreply_fini(void) |
1da177e4 LT |
91 | { |
92 | ebt_unregister_target(&reply_target); | |
93 | } | |
94 | ||
65b4b4e8 AM |
95 | module_init(ebt_arpreply_init); |
96 | module_exit(ebt_arpreply_fini); | |
1da177e4 | 97 | MODULE_LICENSE("GPL"); |