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 ip_send_check(ip_hdr(skb));
36 skb->ignore_df = 1;
37 }
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_id = NF_CT_DEFAULT_ZONE_ID;
46 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
47 if (skb->nfct) {
48 enum ip_conntrack_info ctinfo;
49 const struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
50
51 zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
52 }
53 #endif
54 if (nf_bridge_in_prerouting(skb))
55 return IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id;
56
57 if (hooknum == NF_INET_PRE_ROUTING)
58 return IP_DEFRAG_CONNTRACK_IN + zone_id;
59 else
60 return IP_DEFRAG_CONNTRACK_OUT + zone_id;
61 }
62
ipv4_conntrack_defrag(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)63 static unsigned int ipv4_conntrack_defrag(void *priv,
64 struct sk_buff *skb,
65 const struct nf_hook_state *state)
66 {
67 struct sock *sk = skb->sk;
68
69 if (sk && sk_fullsock(sk) && (sk->sk_family == PF_INET) &&
70 inet_sk(sk)->nodefrag)
71 return NF_ACCEPT;
72
73 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
74 #if !IS_ENABLED(CONFIG_NF_NAT)
75 /* Previously seen (loopback)? Ignore. Do this before
76 fragment check. */
77 if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
78 return NF_ACCEPT;
79 #endif
80 #endif
81 /* Gather fragments. */
82 if (ip_is_fragment(ip_hdr(skb))) {
83 enum ip_defrag_users user =
84 nf_ct_defrag_user(state->hook, skb);
85
86 if (nf_ct_ipv4_gather_frags(state->net, skb, user))
87 return NF_STOLEN;
88 }
89 return NF_ACCEPT;
90 }
91
92 static struct nf_hook_ops ipv4_defrag_ops[] = {
93 {
94 .hook = ipv4_conntrack_defrag,
95 .pf = NFPROTO_IPV4,
96 .hooknum = NF_INET_PRE_ROUTING,
97 .priority = NF_IP_PRI_CONNTRACK_DEFRAG,
98 },
99 {
100 .hook = ipv4_conntrack_defrag,
101 .pf = NFPROTO_IPV4,
102 .hooknum = NF_INET_LOCAL_OUT,
103 .priority = NF_IP_PRI_CONNTRACK_DEFRAG,
104 },
105 };
106
nf_defrag_init(void)107 static int __init nf_defrag_init(void)
108 {
109 return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
110 }
111
nf_defrag_fini(void)112 static void __exit nf_defrag_fini(void)
113 {
114 nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
115 }
116
nf_defrag_ipv4_enable(void)117 void nf_defrag_ipv4_enable(void)
118 {
119 }
120 EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
121
122 module_init(nf_defrag_init);
123 module_exit(nf_defrag_fini);
124
125 MODULE_LICENSE("GPL");
126