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 int __net_init ip6table_mangle_table_init(struct net *net);
  27
  28static const struct xt_table packet_mangler = {
  29        .name           = "mangle",
  30        .valid_hooks    = MANGLE_VALID_HOOKS,
  31        .me             = THIS_MODULE,
  32        .af             = NFPROTO_IPV6,
  33        .priority       = NF_IP6_PRI_MANGLE,
  34        .table_init     = ip6table_mangle_table_init,
  35};
  36
  37static unsigned int
  38ip6t_mangle_out(struct sk_buff *skb, const struct nf_hook_state *state)
  39{
  40        unsigned int ret;
  41        struct in6_addr saddr, daddr;
  42        u_int8_t hop_limit;
  43        u_int32_t flowlabel, mark;
  44        int err;
  45#if 0
  46        /* root is playing with raw sockets. */
  47        if (skb->len < sizeof(struct iphdr) ||
  48            ip_hdrlen(skb) < sizeof(struct iphdr)) {
  49                net_warn_ratelimited("ip6t_hook: happy cracking\n");
  50                return NF_ACCEPT;
  51        }
  52#endif
  53
  54        /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
  55        memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
  56        memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
  57        mark = skb->mark;
  58        hop_limit = ipv6_hdr(skb)->hop_limit;
  59
  60        /* flowlabel and prio (includes version, which shouldn't change either */
  61        flowlabel = *((u_int32_t *)ipv6_hdr(skb));
  62
  63        ret = ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle);
  64
  65        if (ret != NF_DROP && ret != NF_STOLEN &&
  66            (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) ||
  67             !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) ||
  68             skb->mark != mark ||
  69             ipv6_hdr(skb)->hop_limit != hop_limit ||
  70             flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
  71                err = ip6_route_me_harder(state->net, skb);
  72                if (err < 0)
  73                        ret = NF_DROP_ERR(err);
  74        }
  75
  76        return ret;
  77}
  78
  79/* The work comes in here from netfilter.c. */
  80static unsigned int
  81ip6table_mangle_hook(void *priv, struct sk_buff *skb,
  82                     const struct nf_hook_state *state)
  83{
  84        if (state->hook == NF_INET_LOCAL_OUT)
  85                return ip6t_mangle_out(skb, state);
  86        return ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle);
  87}
  88
  89static struct nf_hook_ops *mangle_ops __read_mostly;
  90static int __net_init ip6table_mangle_table_init(struct net *net)
  91{
  92        struct ip6t_replace *repl;
  93        int ret;
  94
  95        if (net->ipv6.ip6table_mangle)
  96                return 0;
  97
  98        repl = ip6t_alloc_initial_table(&packet_mangler);
  99        if (repl == NULL)
 100                return -ENOMEM;
 101        ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops,
 102                                  &net->ipv6.ip6table_mangle);
 103        kfree(repl);
 104        return ret;
 105}
 106
 107static void __net_exit ip6table_mangle_net_exit(struct net *net)
 108{
 109        if (!net->ipv6.ip6table_mangle)
 110                return;
 111
 112        ip6t_unregister_table(net, net->ipv6.ip6table_mangle, mangle_ops);
 113        net->ipv6.ip6table_mangle = NULL;
 114}
 115
 116static struct pernet_operations ip6table_mangle_net_ops = {
 117        .exit = ip6table_mangle_net_exit,
 118};
 119
 120static int __init ip6table_mangle_init(void)
 121{
 122        int ret;
 123
 124        mangle_ops = xt_hook_ops_alloc(&packet_mangler, ip6table_mangle_hook);
 125        if (IS_ERR(mangle_ops))
 126                return PTR_ERR(mangle_ops);
 127
 128        ret = register_pernet_subsys(&ip6table_mangle_net_ops);
 129        if (ret < 0) {
 130                kfree(mangle_ops);
 131                return ret;
 132        }
 133
 134        ret = ip6table_mangle_table_init(&init_net);
 135        if (ret) {
 136                unregister_pernet_subsys(&ip6table_mangle_net_ops);
 137                kfree(mangle_ops);
 138        }
 139        return ret;
 140}
 141
 142static void __exit ip6table_mangle_fini(void)
 143{
 144        unregister_pernet_subsys(&ip6table_mangle_net_ops);
 145        kfree(mangle_ops);
 146}
 147
 148module_init(ip6table_mangle_init);
 149module_exit(ip6table_mangle_fini);
 150