netfilter: nf_conntrack: support conntrack templates
[linux-2.6.git] / net / ipv4 / netfilter / nf_defrag_ipv4.c
1 /* (C) 1999-2001 Paul `Rusty' Russell
2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  */
8
9 #include <linux/types.h>
10 #include <linux/ip.h>
11 #include <linux/netfilter.h>
12 #include <linux/module.h>
13 #include <linux/skbuff.h>
14 #include <net/route.h>
15 #include <net/ip.h>
16
17 #include <linux/netfilter_bridge.h>
18 #include <linux/netfilter_ipv4.h>
19 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
20
21 /* Returns new sk_buff, or NULL */
22 static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
23 {
24         int err;
25
26         skb_orphan(skb);
27
28         local_bh_disable();
29         err = ip_defrag(skb, user);
30         local_bh_enable();
31
32         if (!err)
33                 ip_send_check(ip_hdr(skb));
34
35         return err;
36 }
37
38 static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum,
39                                               struct sk_buff *skb)
40 {
41 #ifdef CONFIG_BRIDGE_NETFILTER
42         if (skb->nf_bridge &&
43             skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)
44                 return IP_DEFRAG_CONNTRACK_BRIDGE_IN;
45 #endif
46         if (hooknum == NF_INET_PRE_ROUTING)
47                 return IP_DEFRAG_CONNTRACK_IN;
48         else
49                 return IP_DEFRAG_CONNTRACK_OUT;
50 }
51
52 static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
53                                           struct sk_buff *skb,
54                                           const struct net_device *in,
55                                           const struct net_device *out,
56                                           int (*okfn)(struct sk_buff *))
57 {
58 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
59 #if !defined(CONFIG_NF_NAT) && !defined(CONFIG_NF_NAT_MODULE)
60         /* Previously seen (loopback)?  Ignore.  Do this before
61            fragment check. */
62         if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
63                 return NF_ACCEPT;
64 #endif
65 #endif
66         /* Gather fragments. */
67         if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
68                 enum ip_defrag_users user = nf_ct_defrag_user(hooknum, skb);
69                 if (nf_ct_ipv4_gather_frags(skb, user))
70                         return NF_STOLEN;
71         }
72         return NF_ACCEPT;
73 }
74
75 static struct nf_hook_ops ipv4_defrag_ops[] = {
76         {
77                 .hook           = ipv4_conntrack_defrag,
78                 .owner          = THIS_MODULE,
79                 .pf             = PF_INET,
80                 .hooknum        = NF_INET_PRE_ROUTING,
81                 .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
82         },
83         {
84                 .hook           = ipv4_conntrack_defrag,
85                 .owner          = THIS_MODULE,
86                 .pf             = PF_INET,
87                 .hooknum        = NF_INET_LOCAL_OUT,
88                 .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
89         },
90 };
91
92 static int __init nf_defrag_init(void)
93 {
94         return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
95 }
96
97 static void __exit nf_defrag_fini(void)
98 {
99         nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
100 }
101
102 void nf_defrag_ipv4_enable(void)
103 {
104 }
105 EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
106
107 module_init(nf_defrag_init);
108 module_exit(nf_defrag_fini);
109
110 MODULE_LICENSE("GPL");