net/netfilter/xt_TEE.c

   1 /*
   2  *      "TEE" target extension for Xtables
   3  *      Copyright © Sebastian Claßen, 2007
   4  *      Jan Engelhardt, 2007-2010
   5  *
   6  *      based on ipt_ROUTE.c from Cédric de Launois
   7  *      <delaunois@info.ucl.be>
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      version 2 or later, as published by the Free Software Foundation.
  12  */
  13 #include <linux/module.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/route.h>
  16 #include <linux/netfilter/x_tables.h>
  17 #include <net/route.h>
  18 #include <net/netfilter/ipv4/nf_dup_ipv4.h>
  19 #include <net/netfilter/ipv6/nf_dup_ipv6.h>
  20 #include <linux/netfilter/xt_TEE.h>
  21
  22 struct xt_tee_priv {
  23         struct notifier_block   notifier;
  24         struct xt_tee_tginfo    *tginfo;
  25         int                     oif;
  26 };
  27
  28 static const union nf_inet_addr tee_zero_address;
  29
  30 static unsigned int
  31 tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
  32 {
  33         const struct xt_tee_tginfo *info = par->targinfo;
  34
  35         nf_dup_ipv4(skb, par->hooknum, &info->gw.in, info->priv->oif);
  36
  37         return XT_CONTINUE;
  38 }
  39
  40 #if IS_ENABLED(CONFIG_IPV6)
  41 static unsigned int
  42 tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)
  43 {
  44         const struct xt_tee_tginfo *info = par->targinfo;
  45
  46         nf_dup_ipv6(skb, par->hooknum, &info->gw.in6, info->priv->oif);
  47
  48         return XT_CONTINUE;
  49 }
  50 #endif
  51
  52 static int tee_netdev_event(struct notifier_block *this, unsigned long event,
  53                             void *ptr)
  54 {
  55         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  56         struct xt_tee_priv *priv;
  57
  58         priv = container_of(this, struct xt_tee_priv, notifier);
  59         switch (event) {
  60         case NETDEV_REGISTER:
  61                 if (!strcmp(dev->name, priv->tginfo->oif))
  62                         priv->oif = dev->ifindex;
  63                 break;
  64         case NETDEV_UNREGISTER:
  65                 if (dev->ifindex == priv->oif)
  66                         priv->oif = -1;
  67                 break;
  68         case NETDEV_CHANGENAME:
  69                 if (!strcmp(dev->name, priv->tginfo->oif))
  70                         priv->oif = dev->ifindex;
  71                 else if (dev->ifindex == priv->oif)
  72                         priv->oif = -1;
  73                 break;
  74         }
  75
  76         return NOTIFY_DONE;
  77 }
  78
  79 static int tee_tg_check(const struct xt_tgchk_param *par)
  80 {
  81         struct xt_tee_tginfo *info = par->targinfo;
  82         struct xt_tee_priv *priv;
  83
  84         /* 0.0.0.0 and :: not allowed */
  85         if (memcmp(&info->gw, &tee_zero_address,
  86                    sizeof(tee_zero_address)) == 0)
  87                 return -EINVAL;
  88
  89         if (info->oif[0]) {
  90                 if (info->oif[sizeof(info->oif)-1] != '\0')
  91                         return -EINVAL;
  92
  93                 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  94                 if (priv == NULL)
  95                         return -ENOMEM;
  96
  97                 priv->tginfo  = info;
  98                 priv->oif     = -1;
  99                 priv->notifier.notifier_call = tee_netdev_event;
 100                 info->priv    = priv;
 101
 102                 register_netdevice_notifier(&priv->notifier);
 103         } else
 104                 info->priv = NULL;
 105
 106         static_key_slow_inc(&xt_tee_enabled);
 107         return 0;
 108 }
 109
 110 static void tee_tg_destroy(const struct xt_tgdtor_param *par)
 111 {
 112         struct xt_tee_tginfo *info = par->targinfo;
 113
 114         if (info->priv) {
 115                 unregister_netdevice_notifier(&info->priv->notifier);
 116                 kfree(info->priv);
 117         }
 118         static_key_slow_dec(&xt_tee_enabled);
 119 }
 120
 121 static struct xt_target tee_tg_reg[] __read_mostly = {
 122         {
 123                 .name       = "TEE",
 124                 .revision   = 1,
 125                 .family     = NFPROTO_IPV4,
 126                 .target     = tee_tg4,
 127                 .targetsize = sizeof(struct xt_tee_tginfo),
 128                 .checkentry = tee_tg_check,
 129                 .destroy    = tee_tg_destroy,
 130                 .me         = THIS_MODULE,
 131         },
 132 #if IS_ENABLED(CONFIG_IPV6)
 133         {
 134                 .name       = "TEE",
 135                 .revision   = 1,
 136                 .family     = NFPROTO_IPV6,
 137                 .target     = tee_tg6,
 138                 .targetsize = sizeof(struct xt_tee_tginfo),
 139                 .checkentry = tee_tg_check,
 140                 .destroy    = tee_tg_destroy,
 141                 .me         = THIS_MODULE,
 142         },
 143 #endif
 144 };
 145
 146 static int __init tee_tg_init(void)
 147 {
 148         return xt_register_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
 149 }
 150
 151 static void __exit tee_tg_exit(void)
 152 {
 153         xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
 154 }
 155
 156 module_init(tee_tg_init);
 157 module_exit(tee_tg_exit);
 158 MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
 159 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
 160 MODULE_DESCRIPTION("Xtables: Reroute packet copy");
 161 MODULE_LICENSE("GPL");
 162 MODULE_ALIAS("ipt_TEE");
 163 MODULE_ALIAS("ip6t_TEE");