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_IP6_PRE_ROUTING) | \
  19                             (1 << NF_IP6_LOCAL_IN) | \
  20                             (1 << NF_IP6_FORWARD) | \
  21                             (1 << NF_IP6_LOCAL_OUT) | \
  22                             (1 << NF_IP6_POST_ROUTING))
  23
  24 #if 0
  25 #define DEBUGP(x, args...)      printk(KERN_DEBUG x, ## args)
  26 #else
  27 #define DEBUGP(x, args...)
  28 #endif
  29
  30 static struct
  31 {
  32         struct ip6t_replace repl;
  33         struct ip6t_standard entries[5];
  34         struct ip6t_error term;
  35 } initial_table __initdata
  36 = { { "mangle", MANGLE_VALID_HOOKS, 6,
  37       sizeof(struct ip6t_standard) * 5 + sizeof(struct ip6t_error),
  38       { [NF_IP6_PRE_ROUTING]    = 0,
  39         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  40         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  41         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  42         [NF_IP6_POST_ROUTING]   = sizeof(struct ip6t_standard) * 4},
  43       { [NF_IP6_PRE_ROUTING]    = 0,
  44         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  45         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  46         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  47         [NF_IP6_POST_ROUTING]   = sizeof(struct ip6t_standard) * 4},
  48       0, NULL, { } },
  49     {
  50             /* PRE_ROUTING */
  51             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  52                 0,
  53                 sizeof(struct ip6t_entry),
  54                 sizeof(struct ip6t_standard),
  55                 0, { 0, 0 }, { } },
  56               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  57                 -NF_ACCEPT - 1 } },
  58             /* LOCAL_IN */
  59             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  60                 0,
  61                 sizeof(struct ip6t_entry),
  62                 sizeof(struct ip6t_standard),
  63                 0, { 0, 0 }, { } },
  64               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  65                 -NF_ACCEPT - 1 } },
  66             /* FORWARD */
  67             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  68                 0,
  69                 sizeof(struct ip6t_entry),
  70                 sizeof(struct ip6t_standard),
  71                 0, { 0, 0 }, { } },
  72               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  73                 -NF_ACCEPT - 1 } },
  74             /* LOCAL_OUT */
  75             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  76                 0,
  77                 sizeof(struct ip6t_entry),
  78                 sizeof(struct ip6t_standard),
  79                 0, { 0, 0 }, { } },
  80               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  81                 -NF_ACCEPT - 1 } },
  82             /* POST_ROUTING */
  83             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  84                 0,
  85                 sizeof(struct ip6t_entry),
  86                 sizeof(struct ip6t_standard),
  87                 0, { 0, 0 }, { } },
  88               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  89                 -NF_ACCEPT - 1 } }
  90     },
  91     /* ERROR */
  92     { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  93         0,
  94         sizeof(struct ip6t_entry),
  95         sizeof(struct ip6t_error),
  96         0, { 0, 0 }, { } },
  97       { { { { IP6T_ALIGN(sizeof(struct ip6t_error_target)), IP6T_ERROR_TARGET } },
  98           { } },
  99         "ERROR"
 100       }
 101     }
 102 };
 103
 104 static struct xt_table packet_mangler = {
 105         .name           = "mangle",
 106         .valid_hooks    = MANGLE_VALID_HOOKS,
 107         .lock           = RW_LOCK_UNLOCKED,
 108         .me             = THIS_MODULE,
 109         .af             = AF_INET6,
 110 };
 111
 112 /* The work comes in here from netfilter.c. */
 113 static unsigned int
 114 ip6t_route_hook(unsigned int hook,
 115          struct sk_buff **pskb,
 116          const struct net_device *in,
 117          const struct net_device *out,
 118          int (*okfn)(struct sk_buff *))
 119 {
 120         return ip6t_do_table(pskb, hook, in, out, &packet_mangler);
 121 }
 122
 123 static unsigned int
 124 ip6t_local_hook(unsigned int hook,
 125                    struct sk_buff **pskb,
 126                    const struct net_device *in,
 127                    const struct net_device *out,
 128                    int (*okfn)(struct sk_buff *))
 129 {
 130
 131         unsigned int ret;
 132         struct in6_addr saddr, daddr;
 133         u_int8_t hop_limit;
 134         u_int32_t flowlabel, mark;
 135
 136 #if 0
 137         /* root is playing with raw sockets. */
 138         if ((*pskb)->len < sizeof(struct iphdr)
 139             || ip_hdrlen(*pskb) < sizeof(struct iphdr)) {
 140                 if (net_ratelimit())
 141                         printk("ip6t_hook: happy cracking.\n");
 142                 return NF_ACCEPT;
 143         }
 144 #endif
 145
 146         /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
 147         memcpy(&saddr, &ipv6_hdr(*pskb)->saddr, sizeof(saddr));
 148         memcpy(&daddr, &ipv6_hdr(*pskb)->daddr, sizeof(daddr));
 149         mark = (*pskb)->mark;
 150         hop_limit = ipv6_hdr(*pskb)->hop_limit;
 151
 152         /* flowlabel and prio (includes version, which shouldn't change either */
 153         flowlabel = *((u_int32_t *)ipv6_hdr(*pskb));
 154
 155         ret = ip6t_do_table(pskb, hook, in, out, &packet_mangler);
 156
 157         if (ret != NF_DROP && ret != NF_STOLEN
 158                 && (memcmp(&ipv6_hdr(*pskb)->saddr, &saddr, sizeof(saddr))
 159                     || memcmp(&ipv6_hdr(*pskb)->daddr, &daddr, sizeof(daddr))
 160                     || (*pskb)->mark != mark
 161                     || ipv6_hdr(*pskb)->hop_limit != hop_limit))
 162                 return ip6_route_me_harder(*pskb) == 0 ? ret : NF_DROP;
 163
 164         return ret;
 165 }
 166
 167 static struct nf_hook_ops ip6t_ops[] = {
 168         {
 169                 .hook           = ip6t_route_hook,
 170                 .owner          = THIS_MODULE,
 171                 .pf             = PF_INET6,
 172                 .hooknum        = NF_IP6_PRE_ROUTING,
 173                 .priority       = NF_IP6_PRI_MANGLE,
 174         },
 175         {
 176                 .hook           = ip6t_local_hook,
 177                 .owner          = THIS_MODULE,
 178                 .pf             = PF_INET6,
 179                 .hooknum        = NF_IP6_LOCAL_IN,
 180                 .priority       = NF_IP6_PRI_MANGLE,
 181         },
 182         {
 183                 .hook           = ip6t_route_hook,
 184                 .owner          = THIS_MODULE,
 185                 .pf             = PF_INET6,
 186                 .hooknum        = NF_IP6_FORWARD,
 187                 .priority       = NF_IP6_PRI_MANGLE,
 188         },
 189         {
 190                 .hook           = ip6t_local_hook,
 191                 .owner          = THIS_MODULE,
 192                 .pf             = PF_INET6,
 193                 .hooknum        = NF_IP6_LOCAL_OUT,
 194                 .priority       = NF_IP6_PRI_MANGLE,
 195         },
 196         {
 197                 .hook           = ip6t_route_hook,
 198                 .owner          = THIS_MODULE,
 199                 .pf             = PF_INET6,
 200                 .hooknum        = NF_IP6_POST_ROUTING,
 201                 .priority       = NF_IP6_PRI_MANGLE,
 202         },
 203 };
 204
 205 static int __init ip6table_mangle_init(void)
 206 {
 207         int ret;
 208
 209         /* Register table */
 210         ret = ip6t_register_table(&packet_mangler, &initial_table.repl);
 211         if (ret < 0)
 212                 return ret;
 213
 214         /* Register hooks */
 215         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 216         if (ret < 0)
 217                 goto cleanup_table;
 218
 219         return ret;
 220
 221  cleanup_table:
 222         ip6t_unregister_table(&packet_mangler);
 223         return ret;
 224 }
 225
 226 static void __exit ip6table_mangle_fini(void)
 227 {
 228         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 229         ip6t_unregister_table(&packet_mangler);
 230 }
 231
 232 module_init(ip6table_mangle_init);
 233 module_exit(ip6table_mangle_fini);