net, netfilter: Remove redundant goto in ebt_ulog_packet
[linux-2.6.git] / net / bridge / netfilter / ebt_snat.c
1 /*
2  *  ebt_snat
3  *
4  *      Authors:
5  *      Bart De Schuymer <bdschuym@pandora.be>
6  *
7  *  June, 2002
8  *
9  */
10 #include <linux/module.h>
11 #include <net/sock.h>
12 #include <linux/if_arp.h>
13 #include <net/arp.h>
14 #include <linux/netfilter.h>
15 #include <linux/netfilter/x_tables.h>
16 #include <linux/netfilter_bridge/ebtables.h>
17 #include <linux/netfilter_bridge/ebt_nat.h>
18
19 static unsigned int
20 ebt_snat_tg(struct sk_buff *skb, const struct xt_action_param *par)
21 {
22         const struct ebt_nat_info *info = par->targinfo;
23
24         if (!skb_make_writable(skb, 0))
25                 return EBT_DROP;
26
27         memcpy(eth_hdr(skb)->h_source, info->mac, ETH_ALEN);
28         if (!(info->target & NAT_ARP_BIT) &&
29             eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) {
30                 const struct arphdr *ap;
31                 struct arphdr _ah;
32
33                 ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah);
34                 if (ap == NULL)
35                         return EBT_DROP;
36                 if (ap->ar_hln != ETH_ALEN)
37                         goto out;
38                 if (skb_store_bits(skb, sizeof(_ah), info->mac,ETH_ALEN))
39                         return EBT_DROP;
40         }
41 out:
42         return info->target | ~EBT_VERDICT_BITS;
43 }
44
45 static int ebt_snat_tg_check(const struct xt_tgchk_param *par)
46 {
47         const struct ebt_nat_info *info = par->targinfo;
48         int tmp;
49
50         tmp = info->target | ~EBT_VERDICT_BITS;
51         if (BASE_CHAIN && tmp == EBT_RETURN)
52                 return -EINVAL;
53
54         if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
55                 return -EINVAL;
56         tmp = info->target | EBT_VERDICT_BITS;
57         if ((tmp & ~NAT_ARP_BIT) != ~NAT_ARP_BIT)
58                 return -EINVAL;
59         return 0;
60 }
61
62 static struct xt_target ebt_snat_tg_reg __read_mostly = {
63         .name           = "snat",
64         .revision       = 0,
65         .family         = NFPROTO_BRIDGE,
66         .table          = "nat",
67         .hooks          = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_POST_ROUTING),
68         .target         = ebt_snat_tg,
69         .checkentry     = ebt_snat_tg_check,
70         .targetsize     = sizeof(struct ebt_nat_info),
71         .me             = THIS_MODULE,
72 };
73
74 static int __init ebt_snat_init(void)
75 {
76         return xt_register_target(&ebt_snat_tg_reg);
77 }
78
79 static void __exit ebt_snat_fini(void)
80 {
81         xt_unregister_target(&ebt_snat_tg_reg);
82 }
83
84 module_init(ebt_snat_init);
85 module_exit(ebt_snat_fini);
86 MODULE_DESCRIPTION("Ebtables: Source MAC address translation");
87 MODULE_LICENSE("GPL");