[NETFILTER]: Remove changelogs and CVS IDs
[linux-2.6.git] / net / netfilter / xt_helper.c
1 /* iptables module to match on related connections */
2 /*
3  * (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  */
9
10 #include <linux/module.h>
11 #include <linux/skbuff.h>
12 #include <linux/netfilter.h>
13 #include <net/netfilter/nf_conntrack.h>
14 #include <net/netfilter/nf_conntrack_core.h>
15 #include <net/netfilter/nf_conntrack_helper.h>
16 #include <linux/netfilter/x_tables.h>
17 #include <linux/netfilter/xt_helper.h>
18
19 MODULE_LICENSE("GPL");
20 MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>");
21 MODULE_DESCRIPTION("iptables helper match module");
22 MODULE_ALIAS("ipt_helper");
23 MODULE_ALIAS("ip6t_helper");
24
25 #if 0
26 #define DEBUGP printk
27 #else
28 #define DEBUGP(format, args...)
29 #endif
30
31 static int
32 match(const struct sk_buff *skb,
33       const struct net_device *in,
34       const struct net_device *out,
35       const struct xt_match *match,
36       const void *matchinfo,
37       int offset,
38       unsigned int protoff,
39       int *hotdrop)
40 {
41         const struct xt_helper_info *info = matchinfo;
42         struct nf_conn *ct;
43         struct nf_conn_help *master_help;
44         enum ip_conntrack_info ctinfo;
45         int ret = info->invert;
46
47         ct = nf_ct_get((struct sk_buff *)skb, &ctinfo);
48         if (!ct) {
49                 DEBUGP("xt_helper: Eek! invalid conntrack?\n");
50                 return ret;
51         }
52
53         if (!ct->master) {
54                 DEBUGP("xt_helper: conntrack %p has no master\n", ct);
55                 return ret;
56         }
57
58         read_lock_bh(&nf_conntrack_lock);
59         master_help = nfct_help(ct->master);
60         if (!master_help || !master_help->helper) {
61                 DEBUGP("xt_helper: master ct %p has no helper\n",
62                         exp->expectant);
63                 goto out_unlock;
64         }
65
66         DEBUGP("master's name = %s , info->name = %s\n",
67                 ct->master->helper->name, info->name);
68
69         if (info->name[0] == '\0')
70                 ret ^= 1;
71         else
72                 ret ^= !strncmp(master_help->helper->name, info->name,
73                                 strlen(master_help->helper->name));
74 out_unlock:
75         read_unlock_bh(&nf_conntrack_lock);
76         return ret;
77 }
78
79 static int check(const char *tablename,
80                  const void *inf,
81                  const struct xt_match *match,
82                  void *matchinfo,
83                  unsigned int hook_mask)
84 {
85         struct xt_helper_info *info = matchinfo;
86
87         if (nf_ct_l3proto_try_module_get(match->family) < 0) {
88                 printk(KERN_WARNING "can't load conntrack support for "
89                                     "proto=%d\n", match->family);
90                 return 0;
91         }
92         info->name[29] = '\0';
93         return 1;
94 }
95
96 static void
97 destroy(const struct xt_match *match, void *matchinfo)
98 {
99         nf_ct_l3proto_module_put(match->family);
100 }
101
102 static struct xt_match xt_helper_match[] = {
103         {
104                 .name           = "helper",
105                 .family         = AF_INET,
106                 .checkentry     = check,
107                 .match          = match,
108                 .destroy        = destroy,
109                 .matchsize      = sizeof(struct xt_helper_info),
110                 .me             = THIS_MODULE,
111         },
112         {
113                 .name           = "helper",
114                 .family         = AF_INET6,
115                 .checkentry     = check,
116                 .match          = match,
117                 .destroy        = destroy,
118                 .matchsize      = sizeof(struct xt_helper_info),
119                 .me             = THIS_MODULE,
120         },
121 };
122
123 static int __init xt_helper_init(void)
124 {
125         return xt_register_matches(xt_helper_match,
126                                    ARRAY_SIZE(xt_helper_match));
127 }
128
129 static void __exit xt_helper_fini(void)
130 {
131         xt_unregister_matches(xt_helper_match, ARRAY_SIZE(xt_helper_match));
132 }
133
134 module_init(xt_helper_init);
135 module_exit(xt_helper_fini);
136