Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * ebt_snat | |
3 | * | |
4 | * Authors: | |
5 | * Bart De Schuymer <bdschuym@pandora.be> | |
6 | * | |
7 | * June, 2002 | |
8 | * | |
9 | */ | |
10 | ||
11 | #include <linux/netfilter_bridge/ebtables.h> | |
12 | #include <linux/netfilter_bridge/ebt_nat.h> | |
13 | #include <linux/module.h> | |
14 | #include <net/sock.h> | |
d12cdc3c BDS |
15 | #include <linux/if_arp.h> |
16 | #include <net/arp.h> | |
1da177e4 LT |
17 | |
18 | static int ebt_target_snat(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_nat_info *info = (struct ebt_nat_info *) data; | |
23 | ||
24 | if (skb_shared(*pskb) || skb_cloned(*pskb)) { | |
25 | struct sk_buff *nskb; | |
26 | ||
27 | nskb = skb_copy(*pskb, GFP_ATOMIC); | |
28 | if (!nskb) | |
29 | return NF_DROP; | |
30 | if ((*pskb)->sk) | |
31 | skb_set_owner_w(nskb, (*pskb)->sk); | |
32 | kfree_skb(*pskb); | |
33 | *pskb = nskb; | |
34 | } | |
35 | memcpy(eth_hdr(*pskb)->h_source, info->mac, ETH_ALEN); | |
d12cdc3c BDS |
36 | if (!(info->target & NAT_ARP_BIT) && |
37 | eth_hdr(*pskb)->h_proto == htons(ETH_P_ARP)) { | |
38 | struct arphdr _ah, *ap; | |
39 | ||
40 | ap = skb_header_pointer(*pskb, 0, sizeof(_ah), &_ah); | |
41 | if (ap == NULL) | |
42 | return EBT_DROP; | |
43 | if (ap->ar_hln != ETH_ALEN) | |
44 | goto out; | |
45 | if (skb_store_bits(*pskb, sizeof(_ah), info->mac,ETH_ALEN)) | |
46 | return EBT_DROP; | |
47 | } | |
48 | out: | |
49 | return info->target | ~EBT_VERDICT_BITS; | |
1da177e4 LT |
50 | } |
51 | ||
52 | static int ebt_target_snat_check(const char *tablename, unsigned int hookmask, | |
53 | const struct ebt_entry *e, void *data, unsigned int datalen) | |
54 | { | |
55 | struct ebt_nat_info *info = (struct ebt_nat_info *) data; | |
d12cdc3c | 56 | int tmp; |
1da177e4 LT |
57 | |
58 | if (datalen != EBT_ALIGN(sizeof(struct ebt_nat_info))) | |
59 | return -EINVAL; | |
d12cdc3c BDS |
60 | tmp = info->target | ~EBT_VERDICT_BITS; |
61 | if (BASE_CHAIN && tmp == EBT_RETURN) | |
1da177e4 LT |
62 | return -EINVAL; |
63 | CLEAR_BASE_CHAIN_BIT; | |
64 | if (strcmp(tablename, "nat")) | |
65 | return -EINVAL; | |
66 | if (hookmask & ~(1 << NF_BR_POST_ROUTING)) | |
67 | return -EINVAL; | |
d12cdc3c BDS |
68 | |
69 | if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0) | |
70 | return -EINVAL; | |
71 | tmp = info->target | EBT_VERDICT_BITS; | |
72 | if ((tmp & ~NAT_ARP_BIT) != ~NAT_ARP_BIT) | |
1da177e4 LT |
73 | return -EINVAL; |
74 | return 0; | |
75 | } | |
76 | ||
77 | static struct ebt_target snat = | |
78 | { | |
79 | .name = EBT_SNAT_TARGET, | |
80 | .target = ebt_target_snat, | |
81 | .check = ebt_target_snat_check, | |
82 | .me = THIS_MODULE, | |
83 | }; | |
84 | ||
65b4b4e8 | 85 | static int __init ebt_snat_init(void) |
1da177e4 LT |
86 | { |
87 | return ebt_register_target(&snat); | |
88 | } | |
89 | ||
65b4b4e8 | 90 | static void __exit ebt_snat_fini(void) |
1da177e4 LT |
91 | { |
92 | ebt_unregister_target(&snat); | |
93 | } | |
94 | ||
65b4b4e8 AM |
95 | module_init(ebt_snat_init); |
96 | module_exit(ebt_snat_fini); | |
1da177e4 | 97 | MODULE_LICENSE("GPL"); |