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/notifier.h>
  18 #include <linux/export.h>
  19
  20 #include <net/fib_rules.h>
  21 #include <net/ipv6.h>
  22 #include <net/addrconf.h>
  23 #include <net/ip6_route.h>
  24 #include <net/netlink.h>
  25
  26 struct fib6_rule {
  27         struct fib_rule         common;
  28         struct rt6key           src;
  29         struct rt6key           dst;
  30         u8                      tclass;
  31 };
  32
  33 static bool fib6_rule_matchall(const struct fib_rule *rule)
  34 {
  35         struct fib6_rule *r = container_of(rule, struct fib6_rule, common);
  36
  37         if (r->dst.plen || r->src.plen || r->tclass)
  38                 return false;
  39         return fib_rule_matchall(rule);
  40 }
  41
  42 bool fib6_rule_default(const struct fib_rule *rule)
  43 {
  44         if (!fib6_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
  45             rule->l3mdev)
  46                 return false;
  47         if (rule->table != RT6_TABLE_LOCAL && rule->table != RT6_TABLE_MAIN)
  48                 return false;
  49         return true;
  50 }
  51 EXPORT_SYMBOL_GPL(fib6_rule_default);
  52
  53 int fib6_rules_dump(struct net *net, struct notifier_block *nb)
  54 {
  55         return fib_rules_dump(net, nb, AF_INET6);
  56 }
  57
  58 unsigned int fib6_rules_seq_read(struct net *net)
  59 {
  60         return fib_rules_seq_read(net, AF_INET6);
  61 }
  62
  63 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
  64                                    const struct sk_buff *skb,
  65                                    int flags, pol_lookup_t lookup)
  66 {
  67         if (net->ipv6.fib6_has_custom_rules) {
  68                 struct fib_lookup_arg arg = {
  69                         .lookup_ptr = lookup,
  70                         .lookup_data = skb,
  71                         .flags = FIB_LOOKUP_NOREF,
  72                 };
  73
  74                 /* update flow if oif or iif point to device enslaved to l3mdev */
  75                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
  76
  77                 fib_rules_lookup(net->ipv6.fib6_rules_ops,
  78                                  flowi6_to_flowi(fl6), flags, &arg);
  79
  80                 if (arg.result)
  81                         return arg.result;
  82         } else {
  83                 struct rt6_info *rt;
  84
  85                 rt = lookup(net, net->ipv6.fib6_local_tbl, fl6, skb, flags);
  86                 if (rt != net->ipv6.ip6_null_entry && rt->dst.error != -EAGAIN)
  87                         return &rt->dst;
  88                 ip6_rt_put(rt);
  89                 rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
  90                 if (rt->dst.error != -EAGAIN)
  91                         return &rt->dst;
  92                 ip6_rt_put(rt);
  93         }
  94
  95         dst_hold(&net->ipv6.ip6_null_entry->dst);
  96         return &net->ipv6.ip6_null_entry->dst;
  97 }
  98
  99 static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
 100                             int flags, struct fib_lookup_arg *arg)
 101 {
 102         struct flowi6 *flp6 = &flp->u.ip6;
 103         struct rt6_info *rt = NULL;
 104         struct fib6_table *table;
 105         struct net *net = rule->fr_net;
 106         pol_lookup_t lookup = arg->lookup_ptr;
 107         int err = 0;
 108         u32 tb_id;
 109
 110         switch (rule->action) {
 111         case FR_ACT_TO_TBL:
 112                 break;
 113         case FR_ACT_UNREACHABLE:
 114                 err = -ENETUNREACH;
 115                 rt = net->ipv6.ip6_null_entry;
 116                 goto discard_pkt;
 117         default:
 118         case FR_ACT_BLACKHOLE:
 119                 err = -EINVAL;
 120                 rt = net->ipv6.ip6_blk_hole_entry;
 121                 goto discard_pkt;
 122         case FR_ACT_PROHIBIT:
 123                 err = -EACCES;
 124                 rt = net->ipv6.ip6_prohibit_entry;
 125                 goto discard_pkt;
 126         }
 127
 128         tb_id = fib_rule_get_table(rule, arg);
 129         table = fib6_get_table(net, tb_id);
 130         if (!table) {
 131                 err = -EAGAIN;
 132                 goto out;
 133         }
 134
 135         rt = lookup(net, table, flp6, arg->lookup_data, flags);
 136         if (rt != net->ipv6.ip6_null_entry) {
 137                 struct fib6_rule *r = (struct fib6_rule *)rule;
 138
 139                 /*
 140                  * If we need to find a source address for this traffic,
 141                  * we check the result if it meets requirement of the rule.
 142                  */
 143                 if ((rule->flags & FIB_RULE_FIND_SADDR) &&
 144                     r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
 145                         struct in6_addr saddr;
 146
 147                         if (ipv6_dev_get_saddr(net,
 148                                                ip6_dst_idev(&rt->dst)->dev,
 149                                                &flp6->daddr,
 150                                                rt6_flags2srcprefs(flags),
 151                                                &saddr))
 152                                 goto again;
 153                         if (!ipv6_prefix_equal(&saddr, &r->src.addr,
 154                                                r->src.plen))
 155                                 goto again;
 156                         flp6->saddr = saddr;
 157                 }
 158                 err = rt->dst.error;
 159                 if (err != -EAGAIN)
 160                         goto out;
 161         }
 162 again:
 163         ip6_rt_put(rt);
 164         err = -EAGAIN;
 165         rt = NULL;
 166         goto out;
 167
 168 discard_pkt:
 169         dst_hold(&rt->dst);
 170 out:
 171         arg->result = rt;
 172         return err;
 173 }
 174
 175 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 176 {
 177         struct rt6_info *rt = (struct rt6_info *) arg->result;
 178         struct net_device *dev = NULL;
 179
 180         if (rt->rt6i_idev)
 181                 dev = rt->rt6i_idev->dev;
 182
 183         /* do not accept result if the route does
 184          * not meet the required prefix length
 185          */
 186         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
 187                 goto suppress_route;
 188
 189         /* do not accept result if the route uses a device
 190          * belonging to a forbidden interface group
 191          */
 192         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 193                 goto suppress_route;
 194
 195         return false;
 196
 197 suppress_route:
 198         ip6_rt_put(rt);
 199         return true;
 200 }
 201
 202 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 203 {
 204         struct fib6_rule *r = (struct fib6_rule *) rule;
 205         struct flowi6 *fl6 = &fl->u.ip6;
 206
 207         if (r->dst.plen &&
 208             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
 209                 return 0;
 210
 211         /*
 212          * If FIB_RULE_FIND_SADDR is set and we do not have a
 213          * source address for the traffic, we defer check for
 214          * source address.
 215          */
 216         if (r->src.plen) {
 217                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
 218                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
 219                                                r->src.plen))
 220                                 return 0;
 221                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
 222                         return 0;
 223         }
 224
 225         if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
 226                 return 0;
 227
 228         if (rule->ip_proto && (rule->ip_proto != fl6->flowi6_proto))
 229                 return 0;
 230
 231         if (fib_rule_port_range_set(&rule->sport_range) &&
 232             !fib_rule_port_inrange(&rule->sport_range, fl6->fl6_sport))
 233                 return 0;
 234
 235         if (fib_rule_port_range_set(&rule->dport_range) &&
 236             !fib_rule_port_inrange(&rule->dport_range, fl6->fl6_dport))
 237                 return 0;
 238
 239         return 1;
 240 }
 241
 242 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
 243         FRA_GENERIC_POLICY,
 244 };
 245
 246 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 247                                struct fib_rule_hdr *frh,
 248                                struct nlattr **tb)
 249 {
 250         int err = -EINVAL;
 251         struct net *net = sock_net(skb->sk);
 252         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 253
 254         if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
 255                 if (rule->table == RT6_TABLE_UNSPEC)
 256                         goto errout;
 257
 258                 if (fib6_new_table(net, rule->table) == NULL) {
 259                         err = -ENOBUFS;
 260                         goto errout;
 261                 }
 262         }
 263
 264         if (frh->src_len)
 265                 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
 266
 267         if (frh->dst_len)
 268                 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
 269
 270         rule6->src.plen = frh->src_len;
 271         rule6->dst.plen = frh->dst_len;
 272         rule6->tclass = frh->tos;
 273
 274         if (fib_rule_requires_fldissect(rule))
 275                 net->ipv6.fib6_rules_require_fldissect++;
 276
 277         net->ipv6.fib6_has_custom_rules = true;
 278         err = 0;
 279 errout:
 280         return err;
 281 }
 282
 283 static int fib6_rule_delete(struct fib_rule *rule)
 284 {
 285         struct net *net = rule->fr_net;
 286
 287         if (net->ipv6.fib6_rules_require_fldissect &&
 288             fib_rule_requires_fldissect(rule))
 289                 net->ipv6.fib6_rules_require_fldissect--;
 290
 291         return 0;
 292 }
 293
 294 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 295                              struct nlattr **tb)
 296 {
 297         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 298
 299         if (frh->src_len && (rule6->src.plen != frh->src_len))
 300                 return 0;
 301
 302         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
 303                 return 0;
 304
 305         if (frh->tos && (rule6->tclass != frh->tos))
 306                 return 0;
 307
 308         if (frh->src_len &&
 309             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
 310                 return 0;
 311
 312         if (frh->dst_len &&
 313             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
 314                 return 0;
 315
 316         return 1;
 317 }
 318
 319 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 320                           struct fib_rule_hdr *frh)
 321 {
 322         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 323
 324         frh->dst_len = rule6->dst.plen;
 325         frh->src_len = rule6->src.plen;
 326         frh->tos = rule6->tclass;
 327
 328         if ((rule6->dst.plen &&
 329              nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
 330             (rule6->src.plen &&
 331              nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
 332                 goto nla_put_failure;
 333         return 0;
 334
 335 nla_put_failure:
 336         return -ENOBUFS;
 337 }
 338
 339 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
 340 {
 341         return nla_total_size(16) /* dst */
 342                + nla_total_size(16); /* src */
 343 }
 344
 345 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
 346         .family                 = AF_INET6,
 347         .rule_size              = sizeof(struct fib6_rule),
 348         .addr_size              = sizeof(struct in6_addr),
 349         .action                 = fib6_rule_action,
 350         .match                  = fib6_rule_match,
 351         .suppress               = fib6_rule_suppress,
 352         .configure              = fib6_rule_configure,
 353         .delete                 = fib6_rule_delete,
 354         .compare                = fib6_rule_compare,
 355         .fill                   = fib6_rule_fill,
 356         .nlmsg_payload          = fib6_rule_nlmsg_payload,
 357         .nlgroup                = RTNLGRP_IPV6_RULE,
 358         .policy                 = fib6_rule_policy,
 359         .owner                  = THIS_MODULE,
 360         .fro_net                = &init_net,
 361 };
 362
 363 static int __net_init fib6_rules_net_init(struct net *net)
 364 {
 365         struct fib_rules_ops *ops;
 366         int err = -ENOMEM;
 367
 368         ops = fib_rules_register(&fib6_rules_ops_template, net);
 369         if (IS_ERR(ops))
 370                 return PTR_ERR(ops);
 371
 372         err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
 373         if (err)
 374                 goto out_fib6_rules_ops;
 375
 376         err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
 377         if (err)
 378                 goto out_fib6_rules_ops;
 379
 380         net->ipv6.fib6_rules_ops = ops;
 381         net->ipv6.fib6_rules_require_fldissect = 0;
 382 out:
 383         return err;
 384
 385 out_fib6_rules_ops:
 386         fib_rules_unregister(ops);
 387         goto out;
 388 }
 389
 390 static void __net_exit fib6_rules_net_exit(struct net *net)
 391 {
 392         rtnl_lock();
 393         fib_rules_unregister(net->ipv6.fib6_rules_ops);
 394         rtnl_unlock();
 395 }
 396
 397 static struct pernet_operations fib6_rules_net_ops = {
 398         .init = fib6_rules_net_init,
 399         .exit = fib6_rules_net_exit,
 400 };
 401
 402 int __init fib6_rules_init(void)
 403 {
 404         return register_pernet_subsys(&fib6_rules_net_ops);
 405 }
 406
 407
 408 void fib6_rules_cleanup(void)
 409 {
 410         unregister_pernet_subsys(&fib6_rules_net_ops);
 411 }