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.h>
  18 #include <net/inet_frag.h>
  19
  20 #include <linux/netfilter_ipv6.h>
  21 #include <linux/netfilter_bridge.h>
  22 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  23 #include <net/netfilter/nf_conntrack.h>
  24 #include <net/netfilter/nf_conntrack_helper.h>
  25 #include <net/netfilter/nf_conntrack_l4proto.h>
  26 #include <net/netfilter/nf_conntrack_l3proto.h>
  27 #include <net/netfilter/nf_conntrack_core.h>
  28 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  29 #endif
  30 #include <net/netfilter/nf_conntrack_zones.h>
  31 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
  32
  33 static DEFINE_MUTEX(defrag6_mutex);
  34
  35 static enum ip6_defrag_users nf_ct6_defrag_user(unsigned int hooknum,
  36                                                 struct sk_buff *skb)
  37 {
  38         u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
  39 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  40         if (skb->nfct) {
  41                 enum ip_conntrack_info ctinfo;
  42                 const struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  43
  44                 zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
  45         }
  46 #endif
  47         if (nf_bridge_in_prerouting(skb))
  48                 return IP6_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id;
  49
  50         if (hooknum == NF_INET_PRE_ROUTING)
  51                 return IP6_DEFRAG_CONNTRACK_IN + zone_id;
  52         else
  53                 return IP6_DEFRAG_CONNTRACK_OUT + zone_id;
  54 }
  55
  56 static unsigned int ipv6_defrag(void *priv,
  57                                 struct sk_buff *skb,
  58                                 const struct nf_hook_state *state)
  59 {
  60         int err;
  61
  62 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
  63         /* Previously seen (loopback)?  */
  64         if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
  65                 return NF_ACCEPT;
  66 #endif
  67
  68         err = nf_ct_frag6_gather(state->net, skb,
  69                                  nf_ct6_defrag_user(state->hook, skb));
  70         /* queued */
  71         if (err == -EINPROGRESS)
  72                 return NF_STOLEN;
  73
  74         return err == 0 ? NF_ACCEPT : NF_DROP;
  75 }
  76
  77 static struct nf_hook_ops ipv6_defrag_ops[] = {
  78         {
  79                 .hook           = ipv6_defrag,
  80                 .pf             = NFPROTO_IPV6,
  81                 .hooknum        = NF_INET_PRE_ROUTING,
  82                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
  83         },
  84         {
  85                 .hook           = ipv6_defrag,
  86                 .pf             = NFPROTO_IPV6,
  87                 .hooknum        = NF_INET_LOCAL_OUT,
  88                 .priority       = NF_IP6_PRI_CONNTRACK_DEFRAG,
  89         },
  90 };
  91
  92 static void __net_exit defrag6_net_exit(struct net *net)
  93 {
  94         if (net->nf.defrag_ipv6) {
  95                 nf_unregister_net_hooks(net, ipv6_defrag_ops,
  96                                         ARRAY_SIZE(ipv6_defrag_ops));
  97                 net->nf.defrag_ipv6 = false;
  98         }
  99 }
 100
 101 static struct pernet_operations defrag6_net_ops = {
 102         .exit = defrag6_net_exit,
 103 };
 104
 105 static int __init nf_defrag_init(void)
 106 {
 107         int ret = 0;
 108
 109         ret = nf_ct_frag6_init();
 110         if (ret < 0) {
 111                 pr_err("nf_defrag_ipv6: can't initialize frag6.\n");
 112                 return ret;
 113         }
 114         ret = register_pernet_subsys(&defrag6_net_ops);
 115         if (ret < 0) {
 116                 pr_err("nf_defrag_ipv6: can't register pernet ops\n");
 117                 goto cleanup_frag6;
 118         }
 119         return ret;
 120
 121 cleanup_frag6:
 122         nf_ct_frag6_cleanup();
 123         return ret;
 124
 125 }
 126
 127 static void __exit nf_defrag_fini(void)
 128 {
 129         unregister_pernet_subsys(&defrag6_net_ops);
 130         nf_ct_frag6_cleanup();
 131 }
 132
 133 int nf_defrag_ipv6_enable(struct net *net)
 134 {
 135         int err = 0;
 136
 137         might_sleep();
 138
 139         if (net->nf.defrag_ipv6)
 140                 return 0;
 141
 142         mutex_lock(&defrag6_mutex);
 143         if (net->nf.defrag_ipv6)
 144                 goto out_unlock;
 145
 146         err = nf_register_net_hooks(net, ipv6_defrag_ops,
 147                                     ARRAY_SIZE(ipv6_defrag_ops));
 148         if (err == 0)
 149                 net->nf.defrag_ipv6 = true;
 150
 151  out_unlock:
 152         mutex_unlock(&defrag6_mutex);
 153         return err;
 154 }
 155 EXPORT_SYMBOL_GPL(nf_defrag_ipv6_enable);
 156
 157 module_init(nf_defrag_init);
 158 module_exit(nf_defrag_fini);
 159
 160 MODULE_LICENSE("GPL");