net/ipv4/netfilter/nft_chain_route_ipv4.c

   1 /*
   2  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
   3  * Copyright (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/list.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/netlink.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/netfilter_ipv4.h>
  17 #include <linux/netfilter/nfnetlink.h>
  18 #include <linux/netfilter/nf_tables.h>
  19 #include <net/netfilter/nf_tables.h>
  20 #include <net/route.h>
  21 #include <net/ip.h>
  22
  23 static unsigned int nf_route_table_hook(const struct nf_hook_ops *ops,
  24                                         struct sk_buff *skb,
  25                                         const struct net_device *in,
  26                                         const struct net_device *out,
  27                                         int (*okfn)(struct sk_buff *))
  28 {
  29         unsigned int ret;
  30         u32 mark;
  31         __be32 saddr, daddr;
  32         u_int8_t tos;
  33         const struct iphdr *iph;
  34
  35         /* root is playing with raw sockets. */
  36         if (skb->len < sizeof(struct iphdr) ||
  37             ip_hdrlen(skb) < sizeof(struct iphdr))
  38                 return NF_ACCEPT;
  39
  40         mark = skb->mark;
  41         iph = ip_hdr(skb);
  42         saddr = iph->saddr;
  43         daddr = iph->daddr;
  44         tos = iph->tos;
  45
  46         ret = nft_do_chain(ops, skb, in, out, okfn);
  47         if (ret != NF_DROP && ret != NF_QUEUE) {
  48                 iph = ip_hdr(skb);
  49
  50                 if (iph->saddr != saddr ||
  51                     iph->daddr != daddr ||
  52                     skb->mark != mark ||
  53                     iph->tos != tos)
  54                         if (ip_route_me_harder(skb, RTN_UNSPEC))
  55                                 ret = NF_DROP;
  56         }
  57         return ret;
  58 }
  59
  60 static struct nf_chain_type nft_chain_route_ipv4 = {
  61         .family         = NFPROTO_IPV4,
  62         .name           = "route",
  63         .type           = NFT_CHAIN_T_ROUTE,
  64         .hook_mask      = (1 << NF_INET_LOCAL_OUT),
  65         .fn             = {
  66                 [NF_INET_LOCAL_OUT]     = nf_route_table_hook,
  67         },
  68         .me             = THIS_MODULE,
  69 };
  70
  71 static int __init nft_chain_route_init(void)
  72 {
  73         return nft_register_chain_type(&nft_chain_route_ipv4);
  74 }
  75
  76 static void __exit nft_chain_route_exit(void)
  77 {
  78         nft_unregister_chain_type(&nft_chain_route_ipv4);
  79 }
  80
  81 module_init(nft_chain_route_init);
  82 module_exit(nft_chain_route_exit);
  83
  84 MODULE_LICENSE("GPL");
  85 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  86 MODULE_ALIAS_NFT_CHAIN(AF_INET, "route");