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#include <linux/ip.h>
15#include <net/ip.h>
16#include <linux/in.h>
17#include <linux/module.h>
18#include <linux/netfilter/x_tables.h>
19#include <linux/netfilter_bridge/ebtables.h>
20#include <linux/netfilter_bridge/ebt_ip.h>
21
22struct tcpudphdr {
23	__be16 src;
24	__be16 dst;
25};
26
27static bool
28ebt_ip_mt(const struct sk_buff *skb, struct xt_action_param *par)
29{
30	const struct ebt_ip_info *info = par->matchinfo;
31	const struct iphdr *ih;
32	struct iphdr _iph;
33	const struct tcpudphdr *pptr;
34	struct tcpudphdr _ports;
35
36	ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
37	if (ih == NULL)
38		return false;
39	if (info->bitmask & EBT_IP_TOS &&
40	   FWINV(info->tos != ih->tos, EBT_IP_TOS))
41		return false;
42	if (info->bitmask & EBT_IP_SOURCE &&
43	   FWINV((ih->saddr & info->smsk) !=
44	   info->saddr, EBT_IP_SOURCE))
45		return false;
46	if ((info->bitmask & EBT_IP_DEST) &&
47	   FWINV((ih->daddr & info->dmsk) !=
48	   info->daddr, EBT_IP_DEST))
49		return false;
50	if (info->bitmask & EBT_IP_PROTO) {
51		if (FWINV(info->protocol != ih->protocol, EBT_IP_PROTO))
52			return false;
53		if (!(info->bitmask & EBT_IP_DPORT) &&
54		    !(info->bitmask & EBT_IP_SPORT))
55			return true;
56		if (ntohs(ih->frag_off) & IP_OFFSET)
57			return false;
58		pptr = skb_header_pointer(skb, ih->ihl*4,
59					  sizeof(_ports), &_ports);
60		if (pptr == NULL)
61			return false;
62		if (info->bitmask & EBT_IP_DPORT) {
63			u32 dst = ntohs(pptr->dst);
64			if (FWINV(dst < info->dport[0] ||
65				  dst > info->dport[1],
66				  EBT_IP_DPORT))
67			return false;
68		}
69		if (info->bitmask & EBT_IP_SPORT) {
70			u32 src = ntohs(pptr->src);
71			if (FWINV(src < info->sport[0] ||
72				  src > info->sport[1],
73				  EBT_IP_SPORT))
74			return false;
75		}
76	}
77	return true;
78}
79
80static int ebt_ip_mt_check(const struct xt_mtchk_param *par)
81{
82	const struct ebt_ip_info *info = par->matchinfo;
83	const struct ebt_entry *e = par->entryinfo;
84
85	if (e->ethproto != htons(ETH_P_IP) ||
86	   e->invflags & EBT_IPROTO)
87		return -EINVAL;
88	if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
89		return -EINVAL;
90	if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
91		if (info->invflags & EBT_IP_PROTO)
92			return -EINVAL;
93		if (info->protocol != IPPROTO_TCP &&
94		    info->protocol != IPPROTO_UDP &&
95		    info->protocol != IPPROTO_UDPLITE &&
96		    info->protocol != IPPROTO_SCTP &&
97		    info->protocol != IPPROTO_DCCP)
98			 return -EINVAL;
99	}
100	if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
101		return -EINVAL;
102	if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
103		return -EINVAL;
104	return 0;
105}
106
107static struct xt_match ebt_ip_mt_reg __read_mostly = {
108	.name		= "ip",
109	.revision	= 0,
110	.family		= NFPROTO_BRIDGE,
111	.match		= ebt_ip_mt,
112	.checkentry	= ebt_ip_mt_check,
113	.matchsize	= sizeof(struct ebt_ip_info),
114	.me		= THIS_MODULE,
115};
116
117static int __init ebt_ip_init(void)
118{
119	return xt_register_match(&ebt_ip_mt_reg);
120}
121
122static void __exit ebt_ip_fini(void)
123{
124	xt_unregister_match(&ebt_ip_mt_reg);
125}
126
127module_init(ebt_ip_init);
128module_exit(ebt_ip_fini);
129MODULE_DESCRIPTION("Ebtables: IPv4 protocol packet match");
130MODULE_LICENSE("GPL");
131