net/netfilter/nft_reject_inet.c

   1 /*
   2  * Copyright (c) 2014 Patrick McHardy <kaber@trash.net>
   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/kernel.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/netlink.h>
  13 #include <linux/netfilter.h>
  14 #include <linux/netfilter/nf_tables.h>
  15 #include <net/netfilter/nf_tables.h>
  16 #include <net/netfilter/nft_reject.h>
  17 #include <net/netfilter/ipv4/nf_reject.h>
  18 #include <net/netfilter/ipv6/nf_reject.h>
  19
  20 static void nft_reject_inet_eval(const struct nft_expr *expr,
  21                                  struct nft_regs *regs,
  22                                  const struct nft_pktinfo *pkt)
  23 {
  24         struct nft_reject *priv = nft_expr_priv(expr);
  25         struct net *net = dev_net((pkt->in != NULL) ? pkt->in : pkt->out);
  26
  27         switch (pkt->pf) {
  28         case NFPROTO_IPV4:
  29                 switch (priv->type) {
  30                 case NFT_REJECT_ICMP_UNREACH:
  31                         nf_send_unreach(pkt->skb, priv->icmp_code,
  32                                         pkt->hook);
  33                         break;
  34                 case NFT_REJECT_TCP_RST:
  35                         nf_send_reset(pkt->skb, pkt->hook);
  36                         break;
  37                 case NFT_REJECT_ICMPX_UNREACH:
  38                         nf_send_unreach(pkt->skb,
  39                                         nft_reject_icmp_code(priv->icmp_code),
  40                                         pkt->hook);
  41                         break;
  42                 }
  43                 break;
  44         case NFPROTO_IPV6:
  45                 switch (priv->type) {
  46                 case NFT_REJECT_ICMP_UNREACH:
  47                         nf_send_unreach6(net, pkt->skb, priv->icmp_code,
  48                                          pkt->hook);
  49                         break;
  50                 case NFT_REJECT_TCP_RST:
  51                         nf_send_reset6(net, pkt->skb, pkt->hook);
  52                         break;
  53                 case NFT_REJECT_ICMPX_UNREACH:
  54                         nf_send_unreach6(net, pkt->skb,
  55                                          nft_reject_icmpv6_code(priv->icmp_code),
  56                                          pkt->hook);
  57                         break;
  58                 }
  59                 break;
  60         }
  61
  62         regs->verdict.code = NF_DROP;
  63 }
  64
  65 static int nft_reject_inet_init(const struct nft_ctx *ctx,
  66                                 const struct nft_expr *expr,
  67                                 const struct nlattr * const tb[])
  68 {
  69         struct nft_reject *priv = nft_expr_priv(expr);
  70         int icmp_code;
  71
  72         if (tb[NFTA_REJECT_TYPE] == NULL)
  73                 return -EINVAL;
  74
  75         priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
  76         switch (priv->type) {
  77         case NFT_REJECT_ICMP_UNREACH:
  78         case NFT_REJECT_ICMPX_UNREACH:
  79                 if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
  80                         return -EINVAL;
  81
  82                 icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
  83                 if (priv->type == NFT_REJECT_ICMPX_UNREACH &&
  84                     icmp_code > NFT_REJECT_ICMPX_MAX)
  85                         return -EINVAL;
  86
  87                 priv->icmp_code = icmp_code;
  88                 break;
  89         case NFT_REJECT_TCP_RST:
  90                 break;
  91         default:
  92                 return -EINVAL;
  93         }
  94         return 0;
  95 }
  96
  97 static int nft_reject_inet_dump(struct sk_buff *skb,
  98                                 const struct nft_expr *expr)
  99 {
 100         const struct nft_reject *priv = nft_expr_priv(expr);
 101
 102         if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
 103                 goto nla_put_failure;
 104
 105         switch (priv->type) {
 106         case NFT_REJECT_ICMP_UNREACH:
 107         case NFT_REJECT_ICMPX_UNREACH:
 108                 if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code))
 109                         goto nla_put_failure;
 110                 break;
 111         default:
 112                 break;
 113         }
 114
 115         return 0;
 116
 117 nla_put_failure:
 118         return -1;
 119 }
 120
 121 static struct nft_expr_type nft_reject_inet_type;
 122 static const struct nft_expr_ops nft_reject_inet_ops = {
 123         .type           = &nft_reject_inet_type,
 124         .size           = NFT_EXPR_SIZE(sizeof(struct nft_reject)),
 125         .eval           = nft_reject_inet_eval,
 126         .init           = nft_reject_inet_init,
 127         .dump           = nft_reject_inet_dump,
 128 };
 129
 130 static struct nft_expr_type nft_reject_inet_type __read_mostly = {
 131         .family         = NFPROTO_INET,
 132         .name           = "reject",
 133         .ops            = &nft_reject_inet_ops,
 134         .policy         = nft_reject_policy,
 135         .maxattr        = NFTA_REJECT_MAX,
 136         .owner          = THIS_MODULE,
 137 };
 138
 139 static int __init nft_reject_inet_module_init(void)
 140 {
 141         return nft_register_expr(&nft_reject_inet_type);
 142 }
 143
 144 static void __exit nft_reject_inet_module_exit(void)
 145 {
 146         nft_unregister_expr(&nft_reject_inet_type);
 147 }
 148
 149 module_init(nft_reject_inet_module_init);
 150 module_exit(nft_reject_inet_module_exit);
 151
 152 MODULE_LICENSE("GPL");
 153 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 154 MODULE_ALIAS_NFT_AF_EXPR(1, "reject");