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         int oif = info->priv ? info->priv->oif : 0;
  35
  36         nf_dup_ipv4(par->net, skb, par->hooknum, &info->gw.in, oif);
  37
  38         return XT_CONTINUE;
  39 }
  40
  41 #if IS_ENABLED(CONFIG_IPV6)
  42 static unsigned int
  43 tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)
  44 {
  45         const struct xt_tee_tginfo *info = par->targinfo;
  46         int oif = info->priv ? info->priv->oif : 0;
  47
  48         nf_dup_ipv6(par->net, skb, par->hooknum, &info->gw.in6, oif);
  49
  50         return XT_CONTINUE;
  51 }
  52 #endif
  53
  54 static int tee_netdev_event(struct notifier_block *this, unsigned long event,
  55                             void *ptr)
  56 {
  57         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  58         struct xt_tee_priv *priv;
  59
  60         priv = container_of(this, struct xt_tee_priv, notifier);
  61         switch (event) {
  62         case NETDEV_REGISTER:
  63                 if (!strcmp(dev->name, priv->tginfo->oif))
  64                         priv->oif = dev->ifindex;
  65                 break;
  66         case NETDEV_UNREGISTER:
  67                 if (dev->ifindex == priv->oif)
  68                         priv->oif = -1;
  69                 break;
  70         case NETDEV_CHANGENAME:
  71                 if (!strcmp(dev->name, priv->tginfo->oif))
  72                         priv->oif = dev->ifindex;
  73                 else if (dev->ifindex == priv->oif)
  74                         priv->oif = -1;
  75                 break;
  76         }
  77
  78         return NOTIFY_DONE;
  79 }
  80
  81 static int tee_tg_check(const struct xt_tgchk_param *par)
  82 {
  83         struct xt_tee_tginfo *info = par->targinfo;
  84         struct xt_tee_priv *priv;
  85
  86         /* 0.0.0.0 and :: not allowed */
  87         if (memcmp(&info->gw, &tee_zero_address,
  88                    sizeof(tee_zero_address)) == 0)
  89                 return -EINVAL;
  90
  91         if (info->oif[0]) {
  92                 int ret;
  93
  94                 if (info->oif[sizeof(info->oif)-1] != '\0')
  95                         return -EINVAL;
  96
  97                 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  98                 if (priv == NULL)
  99                         return -ENOMEM;
 100
 101                 priv->tginfo  = info;
 102                 priv->oif     = -1;
 103                 priv->notifier.notifier_call = tee_netdev_event;
 104                 info->priv    = priv;
 105
 106                 ret = register_netdevice_notifier(&priv->notifier);
 107                 if (ret) {
 108                         kfree(priv);
 109                         return ret;
 110                 }
 111         } else
 112                 info->priv = NULL;
 113
 114         static_key_slow_inc(&xt_tee_enabled);
 115         return 0;
 116 }
 117
 118 static void tee_tg_destroy(const struct xt_tgdtor_param *par)
 119 {
 120         struct xt_tee_tginfo *info = par->targinfo;
 121
 122         if (info->priv) {
 123                 unregister_netdevice_notifier(&info->priv->notifier);
 124                 kfree(info->priv);
 125         }
 126         static_key_slow_dec(&xt_tee_enabled);
 127 }
 128
 129 static struct xt_target tee_tg_reg[] __read_mostly = {
 130         {
 131                 .name       = "TEE",
 132                 .revision   = 1,
 133                 .family     = NFPROTO_IPV4,
 134                 .target     = tee_tg4,
 135                 .targetsize = sizeof(struct xt_tee_tginfo),
 136                 .checkentry = tee_tg_check,
 137                 .destroy    = tee_tg_destroy,
 138                 .me         = THIS_MODULE,
 139         },
 140 #if IS_ENABLED(CONFIG_IPV6)
 141         {
 142                 .name       = "TEE",
 143                 .revision   = 1,
 144                 .family     = NFPROTO_IPV6,
 145                 .target     = tee_tg6,
 146                 .targetsize = sizeof(struct xt_tee_tginfo),
 147                 .checkentry = tee_tg_check,
 148                 .destroy    = tee_tg_destroy,
 149                 .me         = THIS_MODULE,
 150         },
 151 #endif
 152 };
 153
 154 static int __init tee_tg_init(void)
 155 {
 156         return xt_register_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
 157 }
 158
 159 static void __exit tee_tg_exit(void)
 160 {
 161         xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
 162 }
 163
 164 module_init(tee_tg_init);
 165 module_exit(tee_tg_exit);
 166 MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
 167 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
 168 MODULE_DESCRIPTION("Xtables: Reroute packet copy");
 169 MODULE_LICENSE("GPL");
 170 MODULE_ALIAS("ipt_TEE");
 171 MODULE_ALIAS("ip6t_TEE");