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