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5
6#include <linux/types.h>
7#include <linux/ip.h>
8#include <linux/netfilter.h>
9#include <linux/module.h>
10#include <linux/skbuff.h>
11#include <net/netns/generic.h>
12#include <net/route.h>
13#include <net/ip.h>
14
15#include <linux/netfilter_bridge.h>
16#include <linux/netfilter_ipv4.h>
17#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
18#if IS_ENABLED(CONFIG_NF_CONNTRACK)
19#include <net/netfilter/nf_conntrack.h>
20#endif
21#include <net/netfilter/nf_conntrack_zones.h>
22
23static DEFINE_MUTEX(defrag4_mutex);
24
25static 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
40static 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(skb)) {
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
61static 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
74
75 if (skb_nfct(skb) && !nf_ct_is_template((struct nf_conn *)skb_nfct(skb)))
76 return NF_ACCEPT;
77#endif
78 if (skb->_nfct == IP_CT_UNTRACKED)
79 return NF_ACCEPT;
80#endif
81
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
92static const 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
107static void __net_exit defrag4_net_exit(struct net *net)
108{
109 if (net->nf.defrag_ipv4) {
110 nf_unregister_net_hooks(net, ipv4_defrag_ops,
111 ARRAY_SIZE(ipv4_defrag_ops));
112 net->nf.defrag_ipv4 = false;
113 }
114}
115
116static struct pernet_operations defrag4_net_ops = {
117 .exit = defrag4_net_exit,
118};
119
120static int __init nf_defrag_init(void)
121{
122 return register_pernet_subsys(&defrag4_net_ops);
123}
124
125static void __exit nf_defrag_fini(void)
126{
127 unregister_pernet_subsys(&defrag4_net_ops);
128}
129
130int nf_defrag_ipv4_enable(struct net *net)
131{
132 int err = 0;
133
134 might_sleep();
135
136 if (net->nf.defrag_ipv4)
137 return 0;
138
139 mutex_lock(&defrag4_mutex);
140 if (net->nf.defrag_ipv4)
141 goto out_unlock;
142
143 err = nf_register_net_hooks(net, ipv4_defrag_ops,
144 ARRAY_SIZE(ipv4_defrag_ops));
145 if (err == 0)
146 net->nf.defrag_ipv4 = true;
147
148 out_unlock:
149 mutex_unlock(&defrag4_mutex);
150 return err;
151}
152EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
153
154module_init(nf_defrag_init);
155module_exit(nf_defrag_fini);
156
157MODULE_LICENSE("GPL");
158
