netfilter: xtables: change xt_match.checkentry return type
[linux-2.6.git] / net / ipv6 / netfilter / ip6t_ipv6header.c
1 /* ipv6header match - matches IPv6 packets based
2    on whether they contain certain headers */
3
4 /* Original idea: Brad Chapman
5  * Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */
6
7 /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  */
13
14 #include <linux/module.h>
15 #include <linux/skbuff.h>
16 #include <linux/ipv6.h>
17 #include <linux/types.h>
18 #include <net/checksum.h>
19 #include <net/ipv6.h>
20
21 #include <linux/netfilter/x_tables.h>
22 #include <linux/netfilter_ipv6/ip6_tables.h>
23 #include <linux/netfilter_ipv6/ip6t_ipv6header.h>
24
25 MODULE_LICENSE("GPL");
26 MODULE_DESCRIPTION("Xtables: IPv6 header types match");
27 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
28
29 static bool
30 ipv6header_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
31 {
32         const struct ip6t_ipv6header_info *info = par->matchinfo;
33         unsigned int temp;
34         int len;
35         u8 nexthdr;
36         unsigned int ptr;
37
38         /* Make sure this isn't an evil packet */
39
40         /* type of the 1st exthdr */
41         nexthdr = ipv6_hdr(skb)->nexthdr;
42         /* pointer to the 1st exthdr */
43         ptr = sizeof(struct ipv6hdr);
44         /* available length */
45         len = skb->len - ptr;
46         temp = 0;
47
48         while (ip6t_ext_hdr(nexthdr)) {
49                 const struct ipv6_opt_hdr *hp;
50                 struct ipv6_opt_hdr _hdr;
51                 int hdrlen;
52
53                 /* No more exthdr -> evaluate */
54                 if (nexthdr == NEXTHDR_NONE) {
55                         temp |= MASK_NONE;
56                         break;
57                 }
58                 /* Is there enough space for the next ext header? */
59                 if (len < (int)sizeof(struct ipv6_opt_hdr))
60                         return false;
61                 /* ESP -> evaluate */
62                 if (nexthdr == NEXTHDR_ESP) {
63                         temp |= MASK_ESP;
64                         break;
65                 }
66
67                 hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
68                 BUG_ON(hp == NULL);
69
70                 /* Calculate the header length */
71                 if (nexthdr == NEXTHDR_FRAGMENT)
72                         hdrlen = 8;
73                 else if (nexthdr == NEXTHDR_AUTH)
74                         hdrlen = (hp->hdrlen + 2) << 2;
75                 else
76                         hdrlen = ipv6_optlen(hp);
77
78                 /* set the flag */
79                 switch (nexthdr) {
80                 case NEXTHDR_HOP:
81                         temp |= MASK_HOPOPTS;
82                         break;
83                 case NEXTHDR_ROUTING:
84                         temp |= MASK_ROUTING;
85                         break;
86                 case NEXTHDR_FRAGMENT:
87                         temp |= MASK_FRAGMENT;
88                         break;
89                 case NEXTHDR_AUTH:
90                         temp |= MASK_AH;
91                         break;
92                 case NEXTHDR_DEST:
93                         temp |= MASK_DSTOPTS;
94                         break;
95                 default:
96                         return false;
97                         break;
98                 }
99
100                 nexthdr = hp->nexthdr;
101                 len -= hdrlen;
102                 ptr += hdrlen;
103                 if (ptr > skb->len)
104                         break;
105         }
106
107         if (nexthdr != NEXTHDR_NONE && nexthdr != NEXTHDR_ESP)
108                 temp |= MASK_PROTO;
109
110         if (info->modeflag)
111                 return !((temp ^ info->matchflags ^ info->invflags)
112                          & info->matchflags);
113         else {
114                 if (info->invflags)
115                         return temp != info->matchflags;
116                 else
117                         return temp == info->matchflags;
118         }
119 }
120
121 static int ipv6header_mt6_check(const struct xt_mtchk_param *par)
122 {
123         const struct ip6t_ipv6header_info *info = par->matchinfo;
124
125         /* invflags is 0 or 0xff in hard mode */
126         if ((!info->modeflag) && info->invflags != 0x00 &&
127             info->invflags != 0xFF)
128                 return false;
129
130         return true;
131 }
132
133 static struct xt_match ipv6header_mt6_reg __read_mostly = {
134         .name           = "ipv6header",
135         .family         = NFPROTO_IPV6,
136         .match          = ipv6header_mt6,
137         .matchsize      = sizeof(struct ip6t_ipv6header_info),
138         .checkentry     = ipv6header_mt6_check,
139         .destroy        = NULL,
140         .me             = THIS_MODULE,
141 };
142
143 static int __init ipv6header_mt6_init(void)
144 {
145         return xt_register_match(&ipv6header_mt6_reg);
146 }
147
148 static void __exit ipv6header_mt6_exit(void)
149 {
150         xt_unregister_match(&ipv6header_mt6_reg);
151 }
152
153 module_init(ipv6header_mt6_init);
154 module_exit(ipv6header_mt6_exit);