SAFE public projects git trees. - safe/jmp/linux-2.6/blob - net/ipv6/netfilter/ip6table_mangle.c

   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
  14 MODULE_LICENSE("GPL");
  15 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  16 MODULE_DESCRIPTION("ip6tables mangle table");
  17
  18 #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
  19                             (1 << NF_INET_LOCAL_IN) | \
  20                             (1 << NF_INET_FORWARD) | \
  21                             (1 << NF_INET_LOCAL_OUT) | \
  22                             (1 << NF_INET_POST_ROUTING))
  23
  24 static const struct
  25 {
  26         struct ip6t_replace repl;
  27         struct ip6t_standard entries[5];
  28         struct ip6t_error term;
  29 } initial_table __net_initdata = {
  30         .repl = {
  31                 .name = "mangle",
  32                 .valid_hooks = MANGLE_VALID_HOOKS,
  33                 .num_entries = 6,
  34                 .size = sizeof(struct ip6t_standard) * 5 + sizeof(struct ip6t_error),
  35                 .hook_entry = {
  36                         [NF_INET_PRE_ROUTING]   = 0,
  37                         [NF_INET_LOCAL_IN]      = sizeof(struct ip6t_standard),
  38                         [NF_INET_FORWARD]       = sizeof(struct ip6t_standard) * 2,
  39                         [NF_INET_LOCAL_OUT]     = sizeof(struct ip6t_standard) * 3,
  40                         [NF_INET_POST_ROUTING]  = sizeof(struct ip6t_standard) * 4,
  41                 },
  42                 .underflow = {
  43                         [NF_INET_PRE_ROUTING]   = 0,
  44                         [NF_INET_LOCAL_IN]      = sizeof(struct ip6t_standard),
  45                         [NF_INET_FORWARD]       = sizeof(struct ip6t_standard) * 2,
  46                         [NF_INET_LOCAL_OUT]     = sizeof(struct ip6t_standard) * 3,
  47                         [NF_INET_POST_ROUTING]  = sizeof(struct ip6t_standard) * 4,
  48                 },
  49         },
  50         .entries = {
  51                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* PRE_ROUTING */
  52                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_IN */
  53                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* FORWARD */
  54                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_OUT */
  55                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* POST_ROUTING */
  56         },
  57         .term = IP6T_ERROR_INIT,                /* ERROR */
  58 };
  59
  60 static const struct xt_table packet_mangler = {
  61         .name           = "mangle",
  62         .valid_hooks    = MANGLE_VALID_HOOKS,
  63         .me             = THIS_MODULE,
  64         .af             = NFPROTO_IPV6,
  65         .priority       = NF_IP6_PRI_MANGLE,
  66 };
  67
  68 static unsigned int
  69 ip6t_local_out_hook(unsigned int hook,
  70                    struct sk_buff *skb,
  71                    const struct net_device *out,
  72                    int (*okfn)(struct sk_buff *))
  73 {
  74
  75         unsigned int ret;
  76         struct in6_addr saddr, daddr;
  77         u_int8_t hop_limit;
  78         u_int32_t flowlabel, mark;
  79
  80 #if 0
  81         /* root is playing with raw sockets. */
  82         if (skb->len < sizeof(struct iphdr) ||
  83             ip_hdrlen(skb) < sizeof(struct iphdr)) {
  84                 if (net_ratelimit())
  85                         printk("ip6t_hook: happy cracking.\n");
  86                 return NF_ACCEPT;
  87         }
  88 #endif
  89
  90         /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
  91         memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
  92         memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
  93         mark = skb->mark;
  94         hop_limit = ipv6_hdr(skb)->hop_limit;
  95
  96         /* flowlabel and prio (includes version, which shouldn't change either */
  97         flowlabel = *((u_int32_t *)ipv6_hdr(skb));
  98
  99         ret = ip6t_do_table(skb, hook, NULL, out,
 100                             dev_net(out)->ipv6.ip6table_mangle);
 101
 102         if (ret != NF_DROP && ret != NF_STOLEN &&
 103             (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr)) ||
 104              memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr)) ||
 105              skb->mark != mark ||
 106              ipv6_hdr(skb)->hop_limit != hop_limit))
 107                 return ip6_route_me_harder(skb) == 0 ? ret : NF_DROP;
 108
 109         return ret;
 110 }
 111
 112 /* The work comes in here from netfilter.c. */
 113 static unsigned int
 114 ip6table_mangle_hook(unsigned int hook, struct sk_buff *skb,
 115                      const struct net_device *in, const struct net_device *out,
 116                      int (*okfn)(struct sk_buff *))
 117 {
 118         if (hook == NF_INET_LOCAL_OUT)
 119                 return ip6t_local_out_hook(hook, skb, out, okfn);
 120
 121         /* INPUT/FORWARD */
 122         return ip6t_do_table(skb, hook, in, out,
 123                              dev_net(in)->ipv6.ip6table_mangle);
 124 }
 125
 126 static struct nf_hook_ops *mangle_ops __read_mostly;
 127 static int __net_init ip6table_mangle_net_init(struct net *net)
 128 {
 129         /* Register table */
 130         net->ipv6.ip6table_mangle =
 131                 ip6t_register_table(net, &packet_mangler, &initial_table.repl);
 132         if (IS_ERR(net->ipv6.ip6table_mangle))
 133                 return PTR_ERR(net->ipv6.ip6table_mangle);
 134         return 0;
 135 }
 136
 137 static void __net_exit ip6table_mangle_net_exit(struct net *net)
 138 {
 139         ip6t_unregister_table(net, net->ipv6.ip6table_mangle);
 140 }
 141
 142 static struct pernet_operations ip6table_mangle_net_ops = {
 143         .init = ip6table_mangle_net_init,
 144         .exit = ip6table_mangle_net_exit,
 145 };
 146
 147 static int __init ip6table_mangle_init(void)
 148 {
 149         int ret;
 150
 151         ret = register_pernet_subsys(&ip6table_mangle_net_ops);
 152         if (ret < 0)
 153                 return ret;
 154
 155         /* Register hooks */
 156         mangle_ops = xt_hook_link(&packet_mangler, ip6table_mangle_hook);
 157         if (IS_ERR(mangle_ops)) {
 158                 ret = PTR_ERR(mangle_ops);
 159                 goto cleanup_table;
 160         }
 161
 162         return ret;
 163
 164  cleanup_table:
 165         unregister_pernet_subsys(&ip6table_mangle_net_ops);
 166         return ret;
 167 }
 168
 169 static void __exit ip6table_mangle_fini(void)
 170 {
 171         xt_hook_unlink(&packet_mangler, mangle_ops);
 172         unregister_pernet_subsys(&ip6table_mangle_net_ops);
 173 }
 174
 175 module_init(ip6table_mangle_init);
 176 module_exit(ip6table_mangle_fini);