1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
/*
* ebt_ip
*
* Authors:
* Bart De Schuymer <bdschuym@pandora.be>
*
* April, 2002
*
* Changes:
* added ip-sport and ip-dport
* Innominate Security Technologies AG <mhopf@innominate.com>
* September, 2002
*/
#include <linux/ip.h>
#include <net/ip.h>
#include <linux/in.h>
#include <linux/module.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_ip.h>
union pkthdr {
struct {
__be16 src;
__be16 dst;
} tcpudphdr;
struct {
u8 type;
u8 code;
} icmphdr;
struct {
u8 type;
} igmphdr;
};
static bool
ebt_ip_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct ebt_ip_info *info = par->matchinfo;
const struct iphdr *ih;
struct iphdr _iph;
const union pkthdr *pptr;
union pkthdr _pkthdr;
ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
if (ih == NULL)
return false;
if ((info->bitmask & EBT_IP_TOS) &&
NF_INVF(info, EBT_IP_TOS, info->tos != ih->tos))
return false;
if ((info->bitmask & EBT_IP_SOURCE) &&
NF_INVF(info, EBT_IP_SOURCE,
(ih->saddr & info->smsk) != info->saddr))
return false;
if ((info->bitmask & EBT_IP_DEST) &&
NF_INVF(info, EBT_IP_DEST,
(ih->daddr & info->dmsk) != info->daddr))
return false;
if (info->bitmask & EBT_IP_PROTO) {
if (NF_INVF(info, EBT_IP_PROTO, info->protocol != ih->protocol))
return false;
if (!(info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT |
EBT_IP_ICMP | EBT_IP_IGMP)))
return true;
if (ntohs(ih->frag_off) & IP_OFFSET)
return false;
/* min icmp/igmp headersize is 4, so sizeof(_pkthdr) is ok. */
pptr = skb_header_pointer(skb, ih->ihl*4,
sizeof(_pkthdr), &_pkthdr);
if (pptr == NULL)
return false;
if (info->bitmask & EBT_IP_DPORT) {
u32 dst = ntohs(pptr->tcpudphdr.dst);
if (NF_INVF(info, EBT_IP_DPORT,
dst < info->dport[0] ||
dst > info->dport[1]))
return false;
}
if (info->bitmask & EBT_IP_SPORT) {
u32 src = ntohs(pptr->tcpudphdr.src);
if (NF_INVF(info, EBT_IP_SPORT,
src < info->sport[0] ||
src > info->sport[1]))
return false;
}
if ((info->bitmask & EBT_IP_ICMP) &&
NF_INVF(info, EBT_IP_ICMP,
pptr->icmphdr.type < info->icmp_type[0] ||
pptr->icmphdr.type > info->icmp_type[1] ||
pptr->icmphdr.code < info->icmp_code[0] ||
pptr->icmphdr.code > info->icmp_code[1]))
return false;
if ((info->bitmask & EBT_IP_IGMP) &&
NF_INVF(info, EBT_IP_IGMP,
pptr->igmphdr.type < info->igmp_type[0] ||
pptr->igmphdr.type > info->igmp_type[1]))
return false;
}
return true;
}
static int ebt_ip_mt_check(const struct xt_mtchk_param *par)
{
const struct ebt_ip_info *info = par->matchinfo;
const struct ebt_entry *e = par->entryinfo;
if (e->ethproto != htons(ETH_P_IP) ||
e->invflags & EBT_IPROTO)
return -EINVAL;
if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
return -EINVAL;
if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
if (info->invflags & EBT_IP_PROTO)
return -EINVAL;
if (info->protocol != IPPROTO_TCP &&
info->protocol != IPPROTO_UDP &&
info->protocol != IPPROTO_UDPLITE &&
info->protocol != IPPROTO_SCTP &&
info->protocol != IPPROTO_DCCP)
return -EINVAL;
}
if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
return -EINVAL;
if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
return -EINVAL;
if (info->bitmask & EBT_IP_ICMP) {
if ((info->invflags & EBT_IP_PROTO) ||
info->protocol != IPPROTO_ICMP)
return -EINVAL;
if (info->icmp_type[0] > info->icmp_type[1] ||
info->icmp_code[0] > info->icmp_code[1])
return -EINVAL;
}
if (info->bitmask & EBT_IP_IGMP) {
if ((info->invflags & EBT_IP_PROTO) ||
info->protocol != IPPROTO_IGMP)
return -EINVAL;
if (info->igmp_type[0] > info->igmp_type[1])
return -EINVAL;
}
return 0;
}
static struct xt_match ebt_ip_mt_reg __read_mostly = {
.name = "ip",
.revision = 0,
.family = NFPROTO_BRIDGE,
.match = ebt_ip_mt,
.checkentry = ebt_ip_mt_check,
.matchsize = sizeof(struct ebt_ip_info),
.me = THIS_MODULE,
};
static int __init ebt_ip_init(void)
{
return xt_register_match(&ebt_ip_mt_reg);
}
static void __exit ebt_ip_fini(void)
{
xt_unregister_match(&ebt_ip_mt_reg);
}
module_init(ebt_ip_init);
module_exit(ebt_ip_fini);
MODULE_DESCRIPTION("Ebtables: IPv4 protocol packet match");
MODULE_LICENSE("GPL");
|
