LXR linux/net/ipv6/netfilter/ip6table

   1/*
   2 * IPv6 packet mangling table, a port of the IPv4 mangle table to IPv6
   3 *
   4 * Copyright (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
   5 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11#include <linux/module.h>
  12#include <linux/netfilter_ipv6/ip6_tables.h>
  13#include <linux/slab.h>
  14#include <net/ipv6.h>
  15
  16MODULE_LICENSE("GPL");
  17MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  18MODULE_DESCRIPTION("ip6tables mangle table");
  19
  20#define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
  21                            (1 << NF_INET_LOCAL_IN) | \
  22                            (1 << NF_INET_FORWARD) | \
  23                            (1 << NF_INET_LOCAL_OUT) | \
  24                            (1 << NF_INET_POST_ROUTING))
  25
  26static const struct xt_table packet_mangler = {
  27        .name           = "mangle",
  28        .valid_hooks    = MANGLE_VALID_HOOKS,
  29        .me             = THIS_MODULE,
  30        .af             = NFPROTO_IPV6,
  31        .priority       = NF_IP6_PRI_MANGLE,
  32};
  33
  34static unsigned int
  35ip6t_mangle_out(struct sk_buff *skb, const struct net_device *out)
  36{
  37        unsigned int ret;
  38        struct in6_addr saddr, daddr;
  39        u_int8_t hop_limit;
  40        u_int32_t flowlabel, mark;
  41        int err;
  42#if 0
  43        /* root is playing with raw sockets. */
  44        if (skb->len < sizeof(struct iphdr) ||
  45            ip_hdrlen(skb) < sizeof(struct iphdr)) {
  46                net_warn_ratelimited("ip6t_hook: happy cracking\n");
  47                return NF_ACCEPT;
  48        }
  49#endif
  50
  51        /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
  52        memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
  53        memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
  54        mark = skb->mark;
  55        hop_limit = ipv6_hdr(skb)->hop_limit;
  56
  57        /* flowlabel and prio (includes version, which shouldn't change either */
  58        flowlabel = *((u_int32_t *)ipv6_hdr(skb));
  59
  60        ret = ip6t_do_table(skb, NF_INET_LOCAL_OUT, NULL, out,
  61                            dev_net(out)->ipv6.ip6table_mangle);
  62
  63        if (ret != NF_DROP && ret != NF_STOLEN &&
  64            (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) ||
  65             !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) ||
  66             skb->mark != mark ||
  67             ipv6_hdr(skb)->hop_limit != hop_limit ||
  68             flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
  69                err = ip6_route_me_harder(skb);
  70                if (err < 0)
  71                        ret = NF_DROP_ERR(err);
  72        }
  73
  74        return ret;
  75}
  76
  77/* The work comes in here from netfilter.c. */
  78static unsigned int
  79ip6table_mangle_hook(unsigned int hook, struct sk_buff *skb,
  80                     const struct net_device *in, const struct net_device *out,
  81                     int (*okfn)(struct sk_buff *))
  82{
  83        if (hook == NF_INET_LOCAL_OUT)
  84                return ip6t_mangle_out(skb, out);
  85        if (hook == NF_INET_POST_ROUTING)
  86                return ip6t_do_table(skb, hook, in, out,
  87                                     dev_net(out)->ipv6.ip6table_mangle);
  88        /* INPUT/FORWARD */
  89        return ip6t_do_table(skb, hook, in, out,
  90                             dev_net(in)->ipv6.ip6table_mangle);
  91}
  92
  93static struct nf_hook_ops *mangle_ops __read_mostly;
  94static int __net_init ip6table_mangle_net_init(struct net *net)
  95{
  96        struct ip6t_replace *repl;
  97
  98        repl = ip6t_alloc_initial_table(&packet_mangler);
  99        if (repl == NULL)
 100                return -ENOMEM;
 101        net->ipv6.ip6table_mangle =
 102                ip6t_register_table(net, &packet_mangler, repl);
 103        kfree(repl);
 104        return PTR_RET(net->ipv6.ip6table_mangle);
 105}
 106
 107static void __net_exit ip6table_mangle_net_exit(struct net *net)
 108{
 109        ip6t_unregister_table(net, net->ipv6.ip6table_mangle);
 110}
 111
 112static struct pernet_operations ip6table_mangle_net_ops = {
 113        .init = ip6table_mangle_net_init,
 114        .exit = ip6table_mangle_net_exit,
 115};
 116
 117static int __init ip6table_mangle_init(void)
 118{
 119        int ret;
 120
 121        ret = register_pernet_subsys(&ip6table_mangle_net_ops);
 122        if (ret < 0)
 123                return ret;
 124
 125        /* Register hooks */
 126        mangle_ops = xt_hook_link(&packet_mangler, ip6table_mangle_hook);
 127        if (IS_ERR(mangle_ops)) {
 128                ret = PTR_ERR(mangle_ops);
 129                goto cleanup_table;
 130        }
 131
 132        return ret;
 133
 134 cleanup_table:
 135        unregister_pernet_subsys(&ip6table_mangle_net_ops);
 136        return ret;
 137}
 138
 139static void __exit ip6table_mangle_fini(void)
 140{
 141        xt_hook_unlink(&packet_mangler, mangle_ops);
 142        unregister_pernet_subsys(&ip6table_mangle_net_ops);
 143}
 144
 145module_init(ip6table_mangle_init);
 146module_exit(ip6table_mangle_fini);
 147