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 IS_ENABLED(CONFIG_NF_CONNTRACK)
21 #include <net/netfilter/nf_conntrack.h>
22 #endif
23 #include <net/netfilter/nf_conntrack_zones.h>
24
nf_ct_ipv4_gather_frags(struct net * net,struct sk_buff * skb,u_int32_t user)25 static int nf_ct_ipv4_gather_frags(struct net *net, struct sk_buff *skb,
26 u_int32_t user)
27 {
28 int err;
29
30 local_bh_disable();
31 err = ip_defrag(net, skb, user);
32 local_bh_enable();
33
34 if (!err)
35 skb->ignore_df = 1;
36
37 return err;
38 }
39
nf_ct_defrag_user(unsigned int hooknum,struct sk_buff * skb)40 static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum,
41 struct sk_buff *skb)
42 {
43 u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
44 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
45 if (skb->nfct) {
46 enum ip_conntrack_info ctinfo;
47 const struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
48
49 zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
50 }
51 #endif
52 if (nf_bridge_in_prerouting(skb))
53 return IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id;
54
55 if (hooknum == NF_INET_PRE_ROUTING)
56 return IP_DEFRAG_CONNTRACK_IN + zone_id;
57 else
58 return IP_DEFRAG_CONNTRACK_OUT + zone_id;
59 }
60
ipv4_conntrack_defrag(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)61 static unsigned int ipv4_conntrack_defrag(void *priv,
62 struct sk_buff *skb,
63 const struct nf_hook_state *state)
64 {
65 struct sock *sk = skb->sk;
66
67 if (sk && sk_fullsock(sk) && (sk->sk_family == PF_INET) &&
68 inet_sk(sk)->nodefrag)
69 return NF_ACCEPT;
70
71 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
72 #if !IS_ENABLED(CONFIG_NF_NAT)
73 /* Previously seen (loopback)? Ignore. Do this before
74 fragment check. */
75 if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
76 return NF_ACCEPT;
77 #endif
78 #endif
79 /* Gather fragments. */
80 if (ip_is_fragment(ip_hdr(skb))) {
81 enum ip_defrag_users user =
82 nf_ct_defrag_user(state->hook, skb);
83
84 if (nf_ct_ipv4_gather_frags(state->net, skb, user))
85 return NF_STOLEN;
86 }
87 return NF_ACCEPT;
88 }
89
90 static struct nf_hook_ops ipv4_defrag_ops[] = {
91 {
92 .hook = ipv4_conntrack_defrag,
93 .pf = NFPROTO_IPV4,
94 .hooknum = NF_INET_PRE_ROUTING,
95 .priority = NF_IP_PRI_CONNTRACK_DEFRAG,
96 },
97 {
98 .hook = ipv4_conntrack_defrag,
99 .pf = NFPROTO_IPV4,
100 .hooknum = NF_INET_LOCAL_OUT,
101 .priority = NF_IP_PRI_CONNTRACK_DEFRAG,
102 },
103 };
104
nf_defrag_init(void)105 static int __init nf_defrag_init(void)
106 {
107 return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
108 }
109
nf_defrag_fini(void)110 static void __exit nf_defrag_fini(void)
111 {
112 nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
113 }
114
nf_defrag_ipv4_enable(void)115 void nf_defrag_ipv4_enable(void)
116 {
117 }
118 EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
119
120 module_init(nf_defrag_init);
121 module_exit(nf_defrag_fini);
122
123 MODULE_LICENSE("GPL");
124