netfilter: ebtables: do centralized size checking
[linux-2.6.git] / net / bridge / netfilter / ebt_ip6.c
1 /*
2  *  ebt_ip6
3  *
4  *      Authors:
5  *      Manohar Castelino <manohar.r.castelino@intel.com>
6  *      Kuo-Lang Tseng <kuo-lang.tseng@intel.com>
7  *      Jan Engelhardt <jengelh@computergmbh.de>
8  *
9  * Summary:
10  * This is just a modification of the IPv4 code written by
11  * Bart De Schuymer <bdschuym@pandora.be>
12  * with the changes required to support IPv6
13  *
14  *  Jan, 2008
15  */
16 #include <linux/ipv6.h>
17 #include <net/ipv6.h>
18 #include <linux/in.h>
19 #include <linux/module.h>
20 #include <net/dsfield.h>
21 #include <linux/netfilter/x_tables.h>
22 #include <linux/netfilter_bridge/ebtables.h>
23 #include <linux/netfilter_bridge/ebt_ip6.h>
24
25 struct tcpudphdr {
26         __be16 src;
27         __be16 dst;
28 };
29
30 static int ebt_filter_ip6(const struct sk_buff *skb,
31    const struct net_device *in,
32    const struct net_device *out, const void *data,
33    unsigned int datalen)
34 {
35         const struct ebt_ip6_info *info = (struct ebt_ip6_info *)data;
36         const struct ipv6hdr *ih6;
37         struct ipv6hdr _ip6h;
38         const struct tcpudphdr *pptr;
39         struct tcpudphdr _ports;
40         struct in6_addr tmp_addr;
41         int i;
42
43         ih6 = skb_header_pointer(skb, 0, sizeof(_ip6h), &_ip6h);
44         if (ih6 == NULL)
45                 return EBT_NOMATCH;
46         if (info->bitmask & EBT_IP6_TCLASS &&
47            FWINV(info->tclass != ipv6_get_dsfield(ih6), EBT_IP6_TCLASS))
48                 return EBT_NOMATCH;
49         for (i = 0; i < 4; i++)
50                 tmp_addr.in6_u.u6_addr32[i] = ih6->saddr.in6_u.u6_addr32[i] &
51                         info->smsk.in6_u.u6_addr32[i];
52         if (info->bitmask & EBT_IP6_SOURCE &&
53                 FWINV((ipv6_addr_cmp(&tmp_addr, &info->saddr) != 0),
54                         EBT_IP6_SOURCE))
55                 return EBT_NOMATCH;
56         for (i = 0; i < 4; i++)
57                 tmp_addr.in6_u.u6_addr32[i] = ih6->daddr.in6_u.u6_addr32[i] &
58                         info->dmsk.in6_u.u6_addr32[i];
59         if (info->bitmask & EBT_IP6_DEST &&
60            FWINV((ipv6_addr_cmp(&tmp_addr, &info->daddr) != 0), EBT_IP6_DEST))
61                 return EBT_NOMATCH;
62         if (info->bitmask & EBT_IP6_PROTO) {
63                 uint8_t nexthdr = ih6->nexthdr;
64                 int offset_ph;
65
66                 offset_ph = ipv6_skip_exthdr(skb, sizeof(_ip6h), &nexthdr);
67                 if (offset_ph == -1)
68                         return EBT_NOMATCH;
69                 if (FWINV(info->protocol != nexthdr, EBT_IP6_PROTO))
70                         return EBT_NOMATCH;
71                 if (!(info->bitmask & EBT_IP6_DPORT) &&
72                     !(info->bitmask & EBT_IP6_SPORT))
73                         return EBT_MATCH;
74                 pptr = skb_header_pointer(skb, offset_ph, sizeof(_ports),
75                                           &_ports);
76                 if (pptr == NULL)
77                         return EBT_NOMATCH;
78                 if (info->bitmask & EBT_IP6_DPORT) {
79                         u32 dst = ntohs(pptr->dst);
80                         if (FWINV(dst < info->dport[0] ||
81                                   dst > info->dport[1], EBT_IP6_DPORT))
82                                 return EBT_NOMATCH;
83                 }
84                 if (info->bitmask & EBT_IP6_SPORT) {
85                         u32 src = ntohs(pptr->src);
86                         if (FWINV(src < info->sport[0] ||
87                                   src > info->sport[1], EBT_IP6_SPORT))
88                         return EBT_NOMATCH;
89                 }
90                 return EBT_MATCH;
91         }
92         return EBT_MATCH;
93 }
94
95 static int ebt_ip6_check(const char *tablename, unsigned int hookmask,
96    const struct ebt_entry *e, void *data, unsigned int datalen)
97 {
98         struct ebt_ip6_info *info = (struct ebt_ip6_info *)data;
99
100         if (e->ethproto != htons(ETH_P_IPV6) || e->invflags & EBT_IPROTO)
101                 return -EINVAL;
102         if (info->bitmask & ~EBT_IP6_MASK || info->invflags & ~EBT_IP6_MASK)
103                 return -EINVAL;
104         if (info->bitmask & (EBT_IP6_DPORT | EBT_IP6_SPORT)) {
105                 if (info->invflags & EBT_IP6_PROTO)
106                         return -EINVAL;
107                 if (info->protocol != IPPROTO_TCP &&
108                     info->protocol != IPPROTO_UDP &&
109                     info->protocol != IPPROTO_UDPLITE &&
110                     info->protocol != IPPROTO_SCTP &&
111                     info->protocol != IPPROTO_DCCP)
112                          return -EINVAL;
113         }
114         if (info->bitmask & EBT_IP6_DPORT && info->dport[0] > info->dport[1])
115                 return -EINVAL;
116         if (info->bitmask & EBT_IP6_SPORT && info->sport[0] > info->sport[1])
117                 return -EINVAL;
118         return 0;
119 }
120
121 static struct ebt_match filter_ip6 =
122 {
123         .name           = EBT_IP6_MATCH,
124         .match          = ebt_filter_ip6,
125         .check          = ebt_ip6_check,
126         .matchsize      = XT_ALIGN(sizeof(struct ebt_ip6_info)),
127         .me             = THIS_MODULE,
128 };
129
130 static int __init ebt_ip6_init(void)
131 {
132         return ebt_register_match(&filter_ip6);
133 }
134
135 static void __exit ebt_ip6_fini(void)
136 {
137         ebt_unregister_match(&filter_ip6);
138 }
139
140 module_init(ebt_ip6_init);
141 module_exit(ebt_ip6_fini);
142 MODULE_DESCRIPTION("Ebtables: IPv6 protocol packet match");
143 MODULE_LICENSE("GPL");