1// SPDX-License-Identifier: GPL-2.0-only
2/* (C) 1999-2001 Paul `Rusty' Russell
3 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
4 */
5
6#include <linux/types.h>
7#include <linux/ipv6.h>
8#include <linux/in6.h>
9#include <linux/netfilter.h>
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/icmp.h>
13#include <linux/rcupdate.h>
14#include <linux/sysctl.h>
15#include <net/ipv6_frag.h>
16
17#include <linux/netfilter_ipv6.h>
18#include <linux/netfilter_bridge.h>
19#if IS_ENABLED(CONFIG_NF_CONNTRACK)
20#include <net/netfilter/nf_conntrack.h>
21#include <net/netfilter/nf_conntrack_helper.h>
22#include <net/netfilter/nf_conntrack_l4proto.h>
23#include <net/netfilter/nf_conntrack_core.h>
24#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
25#endif
26#include <net/netfilter/nf_conntrack_zones.h>
27#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
28
29static DEFINE_MUTEX(defrag6_mutex);
30
31static enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
32 struct sk_buff *skb)
33{
34 u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
35#if IS_ENABLED(CONFIG_NF_CONNTRACK)
36 if (skb_nfct(skb)) {
37 enum ip_conntrack_info ctinfo;
38 const struct nf_conn *ct = nf_ct_get(skb, ctinfo: &ctinfo);
39
40 zone_id = nf_ct_zone_id(zone: nf_ct_zone(ct), CTINFO2DIR(ctinfo));
41 }
42#endif
43 if (nf_bridge_in_prerouting(skb))
44 return IP6_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id;
45
46 if (hooknum == NF_INET_PRE_ROUTING)
47 return IP6_DEFRAG_CONNTRACK_IN + zone_id;
48 else
49 return IP6_DEFRAG_CONNTRACK_OUT + zone_id;
50}
51
52static unsigned int ipv6_defrag(void *priv,
53 struct sk_buff *skb,
54 const struct nf_hook_state *state)
55{
56 int err;
57
58#if IS_ENABLED(CONFIG_NF_CONNTRACK)
59 /* Previously seen (loopback)? */
60 if (skb_nfct(skb) && !nf_ct_is_template(ct: (struct nf_conn *)skb_nfct(skb)))
61 return NF_ACCEPT;
62
63 if (skb->_nfct == IP_CT_UNTRACKED)
64 return NF_ACCEPT;
65#endif
66
67 err = nf_ct_frag6_gather(net: state->net, skb,
68 user: nf_ct6_defrag_user(hooknum: state->hook, skb));
69 /* queued */
70 if (err == -EINPROGRESS)
71 return NF_STOLEN;
72
73 return err == 0 ? NF_ACCEPT : NF_DROP;
74}
75
76static const struct nf_hook_ops ipv6_defrag_ops[] = {
77 {
78 .hook = ipv6_defrag,
79 .pf = NFPROTO_IPV6,
80 .hooknum = NF_INET_PRE_ROUTING,
81 .priority = NF_IP6_PRI_CONNTRACK_DEFRAG,
82 },
83 {
84 .hook = ipv6_defrag,
85 .pf = NFPROTO_IPV6,
86 .hooknum = NF_INET_LOCAL_OUT,
87 .priority = NF_IP6_PRI_CONNTRACK_DEFRAG,
88 },
89};
90
91static void __net_exit defrag6_net_exit(struct net *net)
92{
93 if (net->nf.defrag_ipv6_users) {
94 nf_unregister_net_hooks(net, reg: ipv6_defrag_ops,
95 ARRAY_SIZE(ipv6_defrag_ops));
96 net->nf.defrag_ipv6_users = 0;
97 }
98}
99
100static const struct nf_defrag_hook defrag_hook = {
101 .owner = THIS_MODULE,
102 .enable = nf_defrag_ipv6_enable,
103 .disable = nf_defrag_ipv6_disable,
104};
105
106static struct pernet_operations defrag6_net_ops = {
107 .exit = defrag6_net_exit,
108};
109
110static int __init nf_defrag_init(void)
111{
112 int ret = 0;
113
114 ret = nf_ct_frag6_init();
115 if (ret < 0) {
116 pr_err("nf_defrag_ipv6: can't initialize frag6.\n");
117 return ret;
118 }
119 ret = register_pernet_subsys(&defrag6_net_ops);
120 if (ret < 0) {
121 pr_err("nf_defrag_ipv6: can't register pernet ops\n");
122 goto cleanup_frag6;
123 }
124
125 rcu_assign_pointer(nf_defrag_v6_hook, &defrag_hook);
126
127 return ret;
128
129cleanup_frag6:
130 nf_ct_frag6_cleanup();
131 return ret;
132
133}
134
135static void __exit nf_defrag_fini(void)
136{
137 rcu_assign_pointer(nf_defrag_v6_hook, NULL);
138 unregister_pernet_subsys(&defrag6_net_ops);
139 nf_ct_frag6_cleanup();
140}
141
142int nf_defrag_ipv6_enable(struct net *net)
143{
144 int err = 0;
145
146 mutex_lock(&defrag6_mutex);
147 if (net->nf.defrag_ipv6_users == UINT_MAX) {
148 err = -EOVERFLOW;
149 goto out_unlock;
150 }
151
152 if (net->nf.defrag_ipv6_users) {
153 net->nf.defrag_ipv6_users++;
154 goto out_unlock;
155 }
156
157 err = nf_register_net_hooks(net, reg: ipv6_defrag_ops,
158 ARRAY_SIZE(ipv6_defrag_ops));
159 if (err == 0)
160 net->nf.defrag_ipv6_users = 1;
161
162 out_unlock:
163 mutex_unlock(lock: &defrag6_mutex);
164 return err;
165}
166EXPORT_SYMBOL_GPL(nf_defrag_ipv6_enable);
167
168void nf_defrag_ipv6_disable(struct net *net)
169{
170 mutex_lock(&defrag6_mutex);
171 if (net->nf.defrag_ipv6_users) {
172 net->nf.defrag_ipv6_users--;
173 if (net->nf.defrag_ipv6_users == 0)
174 nf_unregister_net_hooks(net, reg: ipv6_defrag_ops,
175 ARRAY_SIZE(ipv6_defrag_ops));
176 }
177 mutex_unlock(lock: &defrag6_mutex);
178}
179EXPORT_SYMBOL_GPL(nf_defrag_ipv6_disable);
180
181module_init(nf_defrag_init);
182module_exit(nf_defrag_fini);
183
184MODULE_LICENSE("GPL");
185MODULE_DESCRIPTION("IPv6 defragmentation support");
186

source code of linux/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c