1/*
2 *  ebt_ip
3 *
4 *	Authors:
5 *	Bart De Schuymer <bdschuym@pandora.be>
6 *
7 *  April, 2002
8 *
9 *  Changes:
10 *    added ip-sport and ip-dport
11 *    Innominate Security Technologies AG <mhopf@innominate.com>
12 *    September, 2002
13 */
14
15#include <linux/netfilter_bridge/ebtables.h>
16#include <linux/netfilter_bridge/ebt_ip.h>
17#include <linux/ip.h>
18#include <net/ip.h>
19#include <linux/in.h>
20#include <linux/module.h>
21
22struct tcpudphdr {
23	__be16 src;
24	__be16 dst;
25};
26
27static int ebt_filter_ip(const struct sk_buff *skb, const struct net_device *in,
28   const struct net_device *out, const void *data,
29   unsigned int datalen)
30{
31	struct ebt_ip_info *info = (struct ebt_ip_info *)data;
32	struct iphdr _iph, *ih;
33	struct tcpudphdr _ports, *pptr;
34
35	ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
36	if (ih == NULL)
37		return EBT_NOMATCH;
38	if (info->bitmask & EBT_IP_TOS &&
39	   FWINV(info->tos != ih->tos, EBT_IP_TOS))
40		return EBT_NOMATCH;
41	if (info->bitmask & EBT_IP_SOURCE &&
42	   FWINV((ih->saddr & info->smsk) !=
43	   info->saddr, EBT_IP_SOURCE))
44		return EBT_NOMATCH;
45	if ((info->bitmask & EBT_IP_DEST) &&
46	   FWINV((ih->daddr & info->dmsk) !=
47	   info->daddr, EBT_IP_DEST))
48		return EBT_NOMATCH;
49	if (info->bitmask & EBT_IP_PROTO) {
50		if (FWINV(info->protocol != ih->protocol, EBT_IP_PROTO))
51			return EBT_NOMATCH;
52		if (!(info->bitmask & EBT_IP_DPORT) &&
53		    !(info->bitmask & EBT_IP_SPORT))
54			return EBT_MATCH;
55		if (ntohs(ih->frag_off) & IP_OFFSET)
56			return EBT_NOMATCH;
57		pptr = skb_header_pointer(skb, ih->ihl*4,
58					  sizeof(_ports), &_ports);
59		if (pptr == NULL)
60			return EBT_NOMATCH;
61		if (info->bitmask & EBT_IP_DPORT) {
62			u32 dst = ntohs(pptr->dst);
63			if (FWINV(dst < info->dport[0] ||
64				  dst > info->dport[1],
65				  EBT_IP_DPORT))
66			return EBT_NOMATCH;
67		}
68		if (info->bitmask & EBT_IP_SPORT) {
69			u32 src = ntohs(pptr->src);
70			if (FWINV(src < info->sport[0] ||
71				  src > info->sport[1],
72				  EBT_IP_SPORT))
73			return EBT_NOMATCH;
74		}
75	}
76	return EBT_MATCH;
77}
78
79static int ebt_ip_check(const char *tablename, unsigned int hookmask,
80   const struct ebt_entry *e, void *data, unsigned int datalen)
81{
82	struct ebt_ip_info *info = (struct ebt_ip_info *)data;
83
84	if (datalen != EBT_ALIGN(sizeof(struct ebt_ip_info)))
85		return -EINVAL;
86	if (e->ethproto != htons(ETH_P_IP) ||
87	   e->invflags & EBT_IPROTO)
88		return -EINVAL;
89	if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
90		return -EINVAL;
91	if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
92		if (info->invflags & EBT_IP_PROTO)
93			return -EINVAL;
94		if (info->protocol != IPPROTO_TCP &&
95		    info->protocol != IPPROTO_UDP &&
96		    info->protocol != IPPROTO_UDPLITE &&
97		    info->protocol != IPPROTO_SCTP &&
98		    info->protocol != IPPROTO_DCCP)
99			 return -EINVAL;
100	}
101	if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
102		return -EINVAL;
103	if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
104		return -EINVAL;
105	return 0;
106}
107
108static struct ebt_match filter_ip =
109{
110	.name		= EBT_IP_MATCH,
111	.match		= ebt_filter_ip,
112	.check		= ebt_ip_check,
113	.me		= THIS_MODULE,
114};
115
116static int __init ebt_ip_init(void)
117{
118	return ebt_register_match(&filter_ip);
119}
120
121static void __exit ebt_ip_fini(void)
122{
123	ebt_unregister_match(&filter_ip);
124}
125
126module_init(ebt_ip_init);
127module_exit(ebt_ip_fini);
128MODULE_LICENSE("GPL");
129