net/ipv6/fib6_rules.c

   1 /*
   2  * net/ipv6/fib6_rules.c        IPv6 Routing Policy Rules
   3  *
   4  * Copyright (C)2003-2006 Helsinki University of Technology
   5  * Copyright (C)2003-2006 USAGI/WIDE Project
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License as
   9  *      published by the Free Software Foundation, version 2.
  10  *
  11  * Authors
  12  *      Thomas Graf             <tgraf@suug.ch>
  13  *      Ville Nuorvala          <vnuorval@tcs.hut.fi>
  14  */
  15
  16 #include <linux/netdevice.h>
  17 #include <linux/export.h>
  18
  19 #include <net/fib_rules.h>
  20 #include <net/ipv6.h>
  21 #include <net/addrconf.h>
  22 #include <net/ip6_route.h>
  23 #include <net/netlink.h>
  24
  25 struct fib6_rule {
  26         struct fib_rule         common;
  27         struct rt6key           src;
  28         struct rt6key           dst;
  29         u8                      tclass;
  30 };
  31
  32 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
  33                                    int flags, pol_lookup_t lookup)
  34 {
  35         struct fib_lookup_arg arg = {
  36                 .lookup_ptr = lookup,
  37                 .flags = FIB_LOOKUP_NOREF,
  38         };
  39
  40         /* update flow if oif or iif point to device enslaved to l3mdev */
  41         l3mdev_update_flow(net, flowi6_to_flowi(fl6));
  42
  43         fib_rules_lookup(net->ipv6.fib6_rules_ops,
  44                          flowi6_to_flowi(fl6), flags, &arg);
  45
  46         if (arg.result)
  47                 return arg.result;
  48
  49         dst_hold(&net->ipv6.ip6_null_entry->dst);
  50         return &net->ipv6.ip6_null_entry->dst;
  51 }
  52
  53 static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
  54                             int flags, struct fib_lookup_arg *arg)
  55 {
  56         struct flowi6 *flp6 = &flp->u.ip6;
  57         struct rt6_info *rt = NULL;
  58         struct fib6_table *table;
  59         struct net *net = rule->fr_net;
  60         pol_lookup_t lookup = arg->lookup_ptr;
  61         int err = 0;
  62         u32 tb_id;
  63
  64         switch (rule->action) {
  65         case FR_ACT_TO_TBL:
  66                 break;
  67         case FR_ACT_UNREACHABLE:
  68                 err = -ENETUNREACH;
  69                 rt = net->ipv6.ip6_null_entry;
  70                 goto discard_pkt;
  71         default:
  72         case FR_ACT_BLACKHOLE:
  73                 err = -EINVAL;
  74                 rt = net->ipv6.ip6_blk_hole_entry;
  75                 goto discard_pkt;
  76         case FR_ACT_PROHIBIT:
  77                 err = -EACCES;
  78                 rt = net->ipv6.ip6_prohibit_entry;
  79                 goto discard_pkt;
  80         }
  81
  82         tb_id = fib_rule_get_table(rule, arg);
  83         table = fib6_get_table(net, tb_id);
  84         if (!table) {
  85                 err = -EAGAIN;
  86                 goto out;
  87         }
  88
  89         rt = lookup(net, table, flp6, flags);
  90         if (rt != net->ipv6.ip6_null_entry) {
  91                 struct fib6_rule *r = (struct fib6_rule *)rule;
  92
  93                 /*
  94                  * If we need to find a source address for this traffic,
  95                  * we check the result if it meets requirement of the rule.
  96                  */
  97                 if ((rule->flags & FIB_RULE_FIND_SADDR) &&
  98                     r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
  99                         struct in6_addr saddr;
 100
 101                         if (ipv6_dev_get_saddr(net,
 102                                                ip6_dst_idev(&rt->dst)->dev,
 103                                                &flp6->daddr,
 104                                                rt6_flags2srcprefs(flags),
 105                                                &saddr))
 106                                 goto again;
 107                         if (!ipv6_prefix_equal(&saddr, &r->src.addr,
 108                                                r->src.plen))
 109                                 goto again;
 110                         flp6->saddr = saddr;
 111                 }
 112                 err = rt->dst.error;
 113                 if (err != -EAGAIN)
 114                         goto out;
 115         }
 116 again:
 117         ip6_rt_put(rt);
 118         err = -EAGAIN;
 119         rt = NULL;
 120         goto out;
 121
 122 discard_pkt:
 123         dst_hold(&rt->dst);
 124 out:
 125         arg->result = rt;
 126         return err;
 127 }
 128
 129 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 130 {
 131         struct rt6_info *rt = (struct rt6_info *) arg->result;
 132         struct net_device *dev = NULL;
 133
 134         if (rt->rt6i_idev)
 135                 dev = rt->rt6i_idev->dev;
 136
 137         /* do not accept result if the route does
 138          * not meet the required prefix length
 139          */
 140         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
 141                 goto suppress_route;
 142
 143         /* do not accept result if the route uses a device
 144          * belonging to a forbidden interface group
 145          */
 146         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 147                 goto suppress_route;
 148
 149         return false;
 150
 151 suppress_route:
 152         ip6_rt_put(rt);
 153         return true;
 154 }
 155
 156 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 157 {
 158         struct fib6_rule *r = (struct fib6_rule *) rule;
 159         struct flowi6 *fl6 = &fl->u.ip6;
 160
 161         if (r->dst.plen &&
 162             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
 163                 return 0;
 164
 165         /*
 166          * If FIB_RULE_FIND_SADDR is set and we do not have a
 167          * source address for the traffic, we defer check for
 168          * source address.
 169          */
 170         if (r->src.plen) {
 171                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
 172                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
 173                                                r->src.plen))
 174                                 return 0;
 175                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
 176                         return 0;
 177         }
 178
 179         if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
 180                 return 0;
 181
 182         return 1;
 183 }
 184
 185 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
 186         FRA_GENERIC_POLICY,
 187 };
 188
 189 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 190                                struct fib_rule_hdr *frh,
 191                                struct nlattr **tb)
 192 {
 193         int err = -EINVAL;
 194         struct net *net = sock_net(skb->sk);
 195         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 196
 197         if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
 198                 if (rule->table == RT6_TABLE_UNSPEC)
 199                         goto errout;
 200
 201                 if (fib6_new_table(net, rule->table) == NULL) {
 202                         err = -ENOBUFS;
 203                         goto errout;
 204                 }
 205         }
 206
 207         if (frh->src_len)
 208                 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
 209
 210         if (frh->dst_len)
 211                 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
 212
 213         rule6->src.plen = frh->src_len;
 214         rule6->dst.plen = frh->dst_len;
 215         rule6->tclass = frh->tos;
 216
 217         err = 0;
 218 errout:
 219         return err;
 220 }
 221
 222 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 223                              struct nlattr **tb)
 224 {
 225         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 226
 227         if (frh->src_len && (rule6->src.plen != frh->src_len))
 228                 return 0;
 229
 230         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
 231                 return 0;
 232
 233         if (frh->tos && (rule6->tclass != frh->tos))
 234                 return 0;
 235
 236         if (frh->src_len &&
 237             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
 238                 return 0;
 239
 240         if (frh->dst_len &&
 241             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
 242                 return 0;
 243
 244         return 1;
 245 }
 246
 247 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 248                           struct fib_rule_hdr *frh)
 249 {
 250         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 251
 252         frh->dst_len = rule6->dst.plen;
 253         frh->src_len = rule6->src.plen;
 254         frh->tos = rule6->tclass;
 255
 256         if ((rule6->dst.plen &&
 257              nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
 258             (rule6->src.plen &&
 259              nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
 260                 goto nla_put_failure;
 261         return 0;
 262
 263 nla_put_failure:
 264         return -ENOBUFS;
 265 }
 266
 267 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
 268 {
 269         return nla_total_size(16) /* dst */
 270                + nla_total_size(16); /* src */
 271 }
 272
 273 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
 274         .family                 = AF_INET6,
 275         .rule_size              = sizeof(struct fib6_rule),
 276         .addr_size              = sizeof(struct in6_addr),
 277         .action                 = fib6_rule_action,
 278         .match                  = fib6_rule_match,
 279         .suppress               = fib6_rule_suppress,
 280         .configure              = fib6_rule_configure,
 281         .compare                = fib6_rule_compare,
 282         .fill                   = fib6_rule_fill,
 283         .nlmsg_payload          = fib6_rule_nlmsg_payload,
 284         .nlgroup                = RTNLGRP_IPV6_RULE,
 285         .policy                 = fib6_rule_policy,
 286         .owner                  = THIS_MODULE,
 287         .fro_net                = &init_net,
 288 };
 289
 290 static int __net_init fib6_rules_net_init(struct net *net)
 291 {
 292         struct fib_rules_ops *ops;
 293         int err = -ENOMEM;
 294
 295         ops = fib_rules_register(&fib6_rules_ops_template, net);
 296         if (IS_ERR(ops))
 297                 return PTR_ERR(ops);
 298
 299         err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
 300         if (err)
 301                 goto out_fib6_rules_ops;
 302
 303         err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
 304         if (err)
 305                 goto out_fib6_rules_ops;
 306
 307         net->ipv6.fib6_rules_ops = ops;
 308 out:
 309         return err;
 310
 311 out_fib6_rules_ops:
 312         fib_rules_unregister(ops);
 313         goto out;
 314 }
 315
 316 static void __net_exit fib6_rules_net_exit(struct net *net)
 317 {
 318         rtnl_lock();
 319         fib_rules_unregister(net->ipv6.fib6_rules_ops);
 320         rtnl_unlock();
 321 }
 322
 323 static struct pernet_operations fib6_rules_net_ops = {
 324         .init = fib6_rules_net_init,
 325         .exit = fib6_rules_net_exit,
 326 };
 327
 328 int __init fib6_rules_init(void)
 329 {
 330         return register_pernet_subsys(&fib6_rules_net_ops);
 331 }
 332
 333
 334 void fib6_rules_cleanup(void)
 335 {
 336         unregister_pernet_subsys(&fib6_rules_net_ops);
 337 }