net/ipv6/netfilter/nf_defrag_ipv6_hooks.c

   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/ipv6.h>
  11 #include <linux/in6.h>
  12 #include <linux/netfilter.h>
  13 #include <linux/module.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/icmp.h>
  16 #include <linux/sysctl.h>
  17 #include <net/ipv6_frag.h>
  18
  19 #include <linux/netfilter_ipv6.h>
  20 #include <linux/netfilter_bridge.h>
  21 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  22 #include <net/netfilter/nf_conntrack.h>
  23 #include <net/netfilter/nf_conntrack_helper.h>
  24 #include <net/netfilter/nf_conntrack_l4proto.h>
  25 #include <net/netfilter/nf_conntrack_l3proto.h>
  26 #include <net/netfilter/nf_conntrack_core.h>
  27 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  28 #endif
  29 #include <net/netfilter/nf_conntrack_zones.h>
  30 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
  31
  32 static DEFINE_MUTEX(defrag6_mutex);
  33
  34 static enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
  35                                                 struct sk_buff *skb)
  36 {
  37         u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
  38 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  39         if (skb_nfct(skb)) {
  40                 enum ip_conntrack_info ctinfo;
  41                 const struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  42
  43                 zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
  44         }
  45 #endif
  46         if (nf_bridge_in_prerouting(skb))
  47                 return IP6_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id;
  48
  49         if (hooknum == NF_INET_PRE_ROUTING)
  50                 return IP6_DEFRAG_CONNTRACK_IN + zone_id;
  51         else
  52                 return IP6_DEFRAG_CONNTRACK_OUT + zone_id;
  53 }
  54
  55 static unsigned int ipv6_defrag(void *priv,
  56                                 struct sk_buff *skb,
  57                                 const struct nf_hook_state *state)
  58 {
  59         int err;
  60
  61 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  62         /* Previously seen (loopback)?  */
  63         if (skb_nfct(skb) && !nf_ct_is_template((struct nf_conn *)skb_nfct(skb)))
  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
  91 static void __net_exit defrag6_net_exit(struct net *net)
  92 {
  93         if (net->nf.defrag_ipv6) {
  94                 nf_unregister_net_hooks(net, ipv6_defrag_ops,
  95                                         ARRAY_SIZE(ipv6_defrag_ops));
  96                 net->nf.defrag_ipv6 = false;
  97         }
  98 }
  99
 100 static struct pernet_operations defrag6_net_ops = {
 101         .exit = defrag6_net_exit,
 102 };
 103
 104 static int __init nf_defrag_init(void)
 105 {
 106         int ret = 0;
 107
 108         ret = nf_ct_frag6_init();
 109         if (ret < 0) {
 110                 pr_err("nf_defrag_ipv6: can't initialize frag6.\n");
 111                 return ret;
 112         }
 113         ret = register_pernet_subsys(&defrag6_net_ops);
 114         if (ret < 0) {
 115                 pr_err("nf_defrag_ipv6: can't register pernet ops\n");
 116                 goto cleanup_frag6;
 117         }
 118         return ret;
 119
 120 cleanup_frag6:
 121         nf_ct_frag6_cleanup();
 122         return ret;
 123
 124 }
 125
 126 static void __exit nf_defrag_fini(void)
 127 {
 128         unregister_pernet_subsys(&defrag6_net_ops);
 129         nf_ct_frag6_cleanup();
 130 }
 131
 132 int nf_defrag_ipv6_enable(struct net *net)
 133 {
 134         int err = 0;
 135
 136         might_sleep();
 137
 138         if (net->nf.defrag_ipv6)
 139                 return 0;
 140
 141         mutex_lock(&defrag6_mutex);
 142         if (net->nf.defrag_ipv6)
 143                 goto out_unlock;
 144
 145         err = nf_register_net_hooks(net, ipv6_defrag_ops,
 146                                     ARRAY_SIZE(ipv6_defrag_ops));
 147         if (err == 0)
 148                 net->nf.defrag_ipv6 = true;
 149
 150  out_unlock:
 151         mutex_unlock(&defrag6_mutex);
 152         return err;
 153 }
 154 EXPORT_SYMBOL_GPL(nf_defrag_ipv6_enable);
 155
 156 module_init(nf_defrag_init);
 157 module_exit(nf_defrag_fini);
 158
 159 MODULE_LICENSE("GPL");