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 
29 static DEFINE_MUTEX(defrag6_mutex);
30 
nf_ct6_defrag_user(unsigned int hooknum,struct sk_buff * skb)31 static 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);
39 
40 		zone_id = nf_ct_zone_id(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 
ipv6_defrag(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)52 static 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((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(state->net, skb,
68 				 nf_ct6_defrag_user(state->hook, skb));
69 	/* queued */
70 	if (err == -EINPROGRESS)
71 		return NF_STOLEN;
72 
73 	return err == 0 ? NF_ACCEPT : NF_DROP;
74 }
75 
76 static 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 
defrag6_net_exit(struct net * net)91 static void __net_exit defrag6_net_exit(struct net *net)
92 {
93 	if (net->nf.defrag_ipv6_users) {
94 		nf_unregister_net_hooks(net, ipv6_defrag_ops,
95 					ARRAY_SIZE(ipv6_defrag_ops));
96 		net->nf.defrag_ipv6_users = 0;
97 	}
98 }
99 
100 static 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 
106 static struct pernet_operations defrag6_net_ops = {
107 	.exit = defrag6_net_exit,
108 };
109 
nf_defrag_init(void)110 static 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 
129 cleanup_frag6:
130 	nf_ct_frag6_cleanup();
131 	return ret;
132 
133 }
134 
nf_defrag_fini(void)135 static 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 
nf_defrag_ipv6_enable(struct net * net)142 int 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, 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(&defrag6_mutex);
164 	return err;
165 }
166 EXPORT_SYMBOL_GPL(nf_defrag_ipv6_enable);
167 
nf_defrag_ipv6_disable(struct net * net)168 void 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, ipv6_defrag_ops,
175 						ARRAY_SIZE(ipv6_defrag_ops));
176 	}
177 	mutex_unlock(&defrag6_mutex);
178 }
179 EXPORT_SYMBOL_GPL(nf_defrag_ipv6_disable);
180 
181 module_init(nf_defrag_init);
182 module_exit(nf_defrag_fini);
183 
184 MODULE_LICENSE("GPL");
185