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 };
  66
  67 /* The work comes in here from netfilter.c. */
  68 static unsigned int
  69 ip6t_in_hook(unsigned int hook,
  70          struct sk_buff *skb,
  71          const struct net_device *in,
  72          const struct net_device *out,
  73          int (*okfn)(struct sk_buff *))
  74 {
  75         return ip6t_do_table(skb, hook, in, out,
  76                              dev_net(in)->ipv6.ip6table_mangle);
  77 }
  78
  79 static unsigned int
  80 ip6t_post_routing_hook(unsigned int hook,
  81                 struct sk_buff *skb,
  82                 const struct net_device *in,
  83                 const struct net_device *out,
  84                 int (*okfn)(struct sk_buff *))
  85 {
  86         return ip6t_do_table(skb, hook, in, out,
  87                              dev_net(out)->ipv6.ip6table_mangle);
  88 }
  89
  90 static unsigned int
  91 ip6t_local_out_hook(unsigned int hook,
  92                    struct sk_buff *skb,
  93                    const struct net_device *in,
  94                    const struct net_device *out,
  95                    int (*okfn)(struct sk_buff *))
  96 {
  97
  98         unsigned int ret;
  99         struct in6_addr saddr, daddr;
 100         u_int8_t hop_limit;
 101         u_int32_t flowlabel, mark;
 102
 103 #if 0
 104         /* root is playing with raw sockets. */
 105         if (skb->len < sizeof(struct iphdr)
 106             || ip_hdrlen(skb) < sizeof(struct iphdr)) {
 107                 if (net_ratelimit())
 108                         printk("ip6t_hook: happy cracking.\n");
 109                 return NF_ACCEPT;
 110         }
 111 #endif
 112
 113         /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
 114         memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
 115         memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
 116         mark = skb->mark;
 117         hop_limit = ipv6_hdr(skb)->hop_limit;
 118
 119         /* flowlabel and prio (includes version, which shouldn't change either */
 120         flowlabel = *((u_int32_t *)ipv6_hdr(skb));
 121
 122         ret = ip6t_do_table(skb, hook, in, out,
 123                             dev_net(out)->ipv6.ip6table_mangle);
 124
 125         if (ret != NF_DROP && ret != NF_STOLEN
 126                 && (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr))
 127                     || memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr))
 128                     || skb->mark != mark
 129                     || ipv6_hdr(skb)->hop_limit != hop_limit))
 130                 return ip6_route_me_harder(skb) == 0 ? ret : NF_DROP;
 131
 132         return ret;
 133 }
 134
 135 static struct nf_hook_ops ip6t_ops[] __read_mostly = {
 136         {
 137                 .hook           = ip6t_in_hook,
 138                 .owner          = THIS_MODULE,
 139                 .pf             = NFPROTO_IPV6,
 140                 .hooknum        = NF_INET_PRE_ROUTING,
 141                 .priority       = NF_IP6_PRI_MANGLE,
 142         },
 143         {
 144                 .hook           = ip6t_in_hook,
 145                 .owner          = THIS_MODULE,
 146                 .pf             = NFPROTO_IPV6,
 147                 .hooknum        = NF_INET_LOCAL_IN,
 148                 .priority       = NF_IP6_PRI_MANGLE,
 149         },
 150         {
 151                 .hook           = ip6t_in_hook,
 152                 .owner          = THIS_MODULE,
 153                 .pf             = NFPROTO_IPV6,
 154                 .hooknum        = NF_INET_FORWARD,
 155                 .priority       = NF_IP6_PRI_MANGLE,
 156         },
 157         {
 158                 .hook           = ip6t_local_out_hook,
 159                 .owner          = THIS_MODULE,
 160                 .pf             = NFPROTO_IPV6,
 161                 .hooknum        = NF_INET_LOCAL_OUT,
 162                 .priority       = NF_IP6_PRI_MANGLE,
 163         },
 164         {
 165                 .hook           = ip6t_post_routing_hook,
 166                 .owner          = THIS_MODULE,
 167                 .pf             = NFPROTO_IPV6,
 168                 .hooknum        = NF_INET_POST_ROUTING,
 169                 .priority       = NF_IP6_PRI_MANGLE,
 170         },
 171 };
 172
 173 static int __net_init ip6table_mangle_net_init(struct net *net)
 174 {
 175         /* Register table */
 176         net->ipv6.ip6table_mangle =
 177                 ip6t_register_table(net, &packet_mangler, &initial_table.repl);
 178         if (IS_ERR(net->ipv6.ip6table_mangle))
 179                 return PTR_ERR(net->ipv6.ip6table_mangle);
 180         return 0;
 181 }
 182
 183 static void __net_exit ip6table_mangle_net_exit(struct net *net)
 184 {
 185         ip6t_unregister_table(net->ipv6.ip6table_mangle);
 186 }
 187
 188 static struct pernet_operations ip6table_mangle_net_ops = {
 189         .init = ip6table_mangle_net_init,
 190         .exit = ip6table_mangle_net_exit,
 191 };
 192
 193 static int __init ip6table_mangle_init(void)
 194 {
 195         int ret;
 196
 197         ret = register_pernet_subsys(&ip6table_mangle_net_ops);
 198         if (ret < 0)
 199                 return ret;
 200
 201         /* Register hooks */
 202         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 203         if (ret < 0)
 204                 goto cleanup_table;
 205
 206         return ret;
 207
 208  cleanup_table:
 209         unregister_pernet_subsys(&ip6table_mangle_net_ops);
 210         return ret;
 211 }
 212
 213 static void __exit ip6table_mangle_fini(void)
 214 {
 215         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 216         unregister_pernet_subsys(&ip6table_mangle_net_ops);
 217 }
 218
 219 module_init(ip6table_mangle_init);
 220 module_exit(ip6table_mangle_fini);