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