nf_defrag_ipv6_hooks.c

  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);
 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
 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((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
 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, 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, 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}
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, ipv6_defrag_ops,
175						ARRAY_SIZE(ipv6_defrag_ops));
176	}
177	mutex_unlock(&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");