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 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
21 #include <net/netfilter/nf_conntrack.h>
22 #endif
23 #include <net/netfilter/nf_conntrack_zones.h>
24
25 /* Returns new sk_buff, or NULL */
nf_ct_ipv4_gather_frags(struct sk_buff * skb,u_int32_t user)26 static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
27 {
28 int err;
29
30 skb_orphan(skb);
31
32 local_bh_disable();
33 err = ip_defrag(skb, user);
34 local_bh_enable();
35
36 if (!err)
37 ip_send_check(ip_hdr(skb));
38
39 return err;
40 }
41
nf_ct_defrag_user(unsigned int hooknum,struct sk_buff * skb)42 static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum,
43 struct sk_buff *skb)
44 {
45 u16 zone = NF_CT_DEFAULT_ZONE;
46
47 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
48 if (skb->nfct)
49 zone = nf_ct_zone((struct nf_conn *)skb->nfct);
50 #endif
51
52 #ifdef CONFIG_BRIDGE_NETFILTER
53 if (skb->nf_bridge &&
54 skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)
55 return IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone;
56 #endif
57 if (hooknum == NF_INET_PRE_ROUTING)
58 return IP_DEFRAG_CONNTRACK_IN + zone;
59 else
60 return IP_DEFRAG_CONNTRACK_OUT + zone;
61 }
62
ipv4_conntrack_defrag(unsigned int hooknum,struct sk_buff * skb,const struct net_device * in,const struct net_device * out,int (* okfn)(struct sk_buff *))63 static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
64 struct sk_buff *skb,
65 const struct net_device *in,
66 const struct net_device *out,
67 int (*okfn)(struct sk_buff *))
68 {
69 struct sock *sk = skb->sk;
70 struct inet_sock *inet = inet_sk(skb->sk);
71
72 if (sk && (sk->sk_family == PF_INET) &&
73 inet->nodefrag)
74 return NF_ACCEPT;
75
76 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
77 #if !defined(CONFIG_NF_NAT) && !defined(CONFIG_NF_NAT_MODULE)
78 /* Previously seen (loopback)? Ignore. Do this before
79 fragment check. */
80 if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
81 return NF_ACCEPT;
82 #endif
83 #endif
84 /* Gather fragments. */
85 if (ip_is_fragment(ip_hdr(skb))) {
86 enum ip_defrag_users user = nf_ct_defrag_user(hooknum, skb);
87 if (nf_ct_ipv4_gather_frags(skb, user))
88 return NF_STOLEN;
89 }
90 return NF_ACCEPT;
91 }
92
93 static struct nf_hook_ops ipv4_defrag_ops[] = {
94 {
95 .hook = ipv4_conntrack_defrag,
96 .owner = THIS_MODULE,
97 .pf = PF_INET,
98 .hooknum = NF_INET_PRE_ROUTING,
99 .priority = NF_IP_PRI_CONNTRACK_DEFRAG,
100 },
101 {
102 .hook = ipv4_conntrack_defrag,
103 .owner = THIS_MODULE,
104 .pf = PF_INET,
105 .hooknum = NF_INET_LOCAL_OUT,
106 .priority = NF_IP_PRI_CONNTRACK_DEFRAG,
107 },
108 };
109
nf_defrag_init(void)110 static int __init nf_defrag_init(void)
111 {
112 return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
113 }
114
nf_defrag_fini(void)115 static void __exit nf_defrag_fini(void)
116 {
117 nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
118 }
119
nf_defrag_ipv4_enable(void)120 void nf_defrag_ipv4_enable(void)
121 {
122 }
123 EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
124
125 module_init(nf_defrag_init);
126 module_exit(nf_defrag_fini);
127
128 MODULE_LICENSE("GPL");
129