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
  15MODULE_LICENSE("GPL");
  16MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  17MODULE_DESCRIPTION("ip6tables mangle table");
  18
  19#define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
  20                            (1 << NF_INET_LOCAL_IN) | \
  21                            (1 << NF_INET_FORWARD) | \
  22                            (1 << NF_INET_LOCAL_OUT) | \
  23                            (1 << NF_INET_POST_ROUTING))
  24
  25static const struct xt_table packet_mangler = {
  26        .name           = "mangle",
  27        .valid_hooks    = MANGLE_VALID_HOOKS,
  28        .me             = THIS_MODULE,
  29        .af             = NFPROTO_IPV6,
  30        .priority       = NF_IP6_PRI_MANGLE,
  31};
  32
  33static unsigned int
  34ip6t_mangle_out(struct sk_buff *skb, const struct net_device *out)
  35{
  36        unsigned int ret;
  37        struct in6_addr saddr, daddr;
  38        u_int8_t hop_limit;
  39        u_int32_t flowlabel, mark;
  40
  41#if 0
  42        /* root is playing with raw sockets. */
  43        if (skb->len < sizeof(struct iphdr) ||
  44            ip_hdrlen(skb) < sizeof(struct iphdr)) {
  45                if (net_ratelimit())
  46                        pr_warning("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            (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr)) ||
  65             memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr)) ||
  66             skb->mark != mark ||
  67             ipv6_hdr(skb)->hop_limit != hop_limit))
  68                return ip6_route_me_harder(skb) == 0 ? ret : NF_DROP;
  69
  70        return ret;
  71}
  72
  73/* The work comes in here from netfilter.c. */
  74static unsigned int
  75ip6table_mangle_hook(unsigned int hook, struct sk_buff *skb,
  76                     const struct net_device *in, const struct net_device *out,
  77                     int (*okfn)(struct sk_buff *))
  78{
  79        if (hook == NF_INET_LOCAL_OUT)
  80                return ip6t_mangle_out(skb, out);
  81        if (hook == NF_INET_POST_ROUTING)
  82                return ip6t_do_table(skb, hook, in, out,
  83                                     dev_net(out)->ipv6.ip6table_mangle);
  84        /* INPUT/FORWARD */
  85        return ip6t_do_table(skb, hook, in, out,
  86                             dev_net(in)->ipv6.ip6table_mangle);
  87}
  88
  89static struct nf_hook_ops *mangle_ops __read_mostly;
  90static int __net_init ip6table_mangle_net_init(struct net *net)
  91{
  92        struct ip6t_replace *repl;
  93
  94        repl = ip6t_alloc_initial_table(&packet_mangler);
  95        if (repl == NULL)
  96                return -ENOMEM;
  97        net->ipv6.ip6table_mangle =
  98                ip6t_register_table(net, &packet_mangler, repl);
  99        kfree(repl);
 100        if (IS_ERR(net->ipv6.ip6table_mangle))
 101                return PTR_ERR(net->ipv6.ip6table_mangle);
 102        return 0;
 103}
 104
 105static void __net_exit ip6table_mangle_net_exit(struct net *net)
 106{
 107        ip6t_unregister_table(net, net->ipv6.ip6table_mangle);
 108}
 109
 110static struct pernet_operations ip6table_mangle_net_ops = {
 111        .init = ip6table_mangle_net_init,
 112        .exit = ip6table_mangle_net_exit,
 113};
 114
 115static int __init ip6table_mangle_init(void)
 116{
 117        int ret;
 118
 119        ret = register_pernet_subsys(&ip6table_mangle_net_ops);
 120        if (ret < 0)
 121                return ret;
 122
 123        /* Register hooks */
 124        mangle_ops = xt_hook_link(&packet_mangler, ip6table_mangle_hook);
 125        if (IS_ERR(mangle_ops)) {
 126                ret = PTR_ERR(mangle_ops);
 127                goto cleanup_table;
 128        }
 129
 130        return ret;
 131
 132 cleanup_table:
 133        unregister_pernet_subsys(&ip6table_mangle_net_ops);
 134        return ret;
 135}
 136
 137static void __exit ip6table_mangle_fini(void)
 138{
 139        xt_hook_unlink(&packet_mangler, mangle_ops);
 140        unregister_pernet_subsys(&ip6table_mangle_net_ops);
 141}
 142
 143module_init(ip6table_mangle_init);
 144module_exit(ip6table_mangle_fini);
 145