net/ipv6/fib6_rules.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * net/ipv6/fib6_rules.c        IPv6 Routing Policy Rules
   4  *
   5  * Copyright (C)2003-2006 Helsinki University of Technology
   6  * Copyright (C)2003-2006 USAGI/WIDE Project
   7  *
   8  * Authors
   9  *      Thomas Graf             <tgraf@suug.ch>
  10  *      Ville Nuorvala          <vnuorval@tcs.hut.fi>
  11  */
  12
  13 #include <linux/netdevice.h>
  14 #include <linux/notifier.h>
  15 #include <linux/export.h>
  16 #include <linux/indirect_call_wrapper.h>
  17
  18 #include <net/fib_rules.h>
  19 #include <net/ipv6.h>
  20 #include <net/addrconf.h>
  21 #include <net/ip6_route.h>
  22 #include <net/netlink.h>
  23
  24 struct fib6_rule {
  25         struct fib_rule         common;
  26         struct rt6key           src;
  27         struct rt6key           dst;
  28         u8                      tclass;
  29 };
  30
  31 static bool fib6_rule_matchall(const struct fib_rule *rule)
  32 {
  33         struct fib6_rule *r = container_of(rule, struct fib6_rule, common);
  34
  35         if (r->dst.plen || r->src.plen || r->tclass)
  36                 return false;
  37         return fib_rule_matchall(rule);
  38 }
  39
  40 bool fib6_rule_default(const struct fib_rule *rule)
  41 {
  42         if (!fib6_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
  43             rule->l3mdev)
  44                 return false;
  45         if (rule->table != RT6_TABLE_LOCAL && rule->table != RT6_TABLE_MAIN)
  46                 return false;
  47         return true;
  48 }
  49 EXPORT_SYMBOL_GPL(fib6_rule_default);
  50
  51 int fib6_rules_dump(struct net *net, struct notifier_block *nb,
  52                     struct netlink_ext_ack *extack)
  53 {
  54         return fib_rules_dump(net, nb, AF_INET6, extack);
  55 }
  56
  57 unsigned int fib6_rules_seq_read(struct net *net)
  58 {
  59         return fib_rules_seq_read(net, AF_INET6);
  60 }
  61
  62 /* called with rcu lock held; no reference taken on fib6_info */
  63 int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
  64                 struct fib6_result *res, int flags)
  65 {
  66         int err;
  67
  68         if (net->ipv6.fib6_has_custom_rules) {
  69                 struct fib_lookup_arg arg = {
  70                         .lookup_ptr = fib6_table_lookup,
  71                         .lookup_data = &oif,
  72                         .result = res,
  73                         .flags = FIB_LOOKUP_NOREF,
  74                 };
  75
  76                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
  77
  78                 err = fib_rules_lookup(net->ipv6.fib6_rules_ops,
  79                                        flowi6_to_flowi(fl6), flags, &arg);
  80         } else {
  81                 err = fib6_table_lookup(net, net->ipv6.fib6_local_tbl, oif,
  82                                         fl6, res, flags);
  83                 if (err || res->f6i == net->ipv6.fib6_null_entry)
  84                         err = fib6_table_lookup(net, net->ipv6.fib6_main_tbl,
  85                                                 oif, fl6, res, flags);
  86         }
  87
  88         return err;
  89 }
  90
  91 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
  92                                    const struct sk_buff *skb,
  93                                    int flags, pol_lookup_t lookup)
  94 {
  95         if (net->ipv6.fib6_has_custom_rules) {
  96                 struct fib6_result res = {};
  97                 struct fib_lookup_arg arg = {
  98                         .lookup_ptr = lookup,
  99                         .lookup_data = skb,
 100                         .result = &res,
 101                         .flags = FIB_LOOKUP_NOREF,
 102                 };
 103
 104                 /* update flow if oif or iif point to device enslaved to l3mdev */
 105                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
 106
 107                 fib_rules_lookup(net->ipv6.fib6_rules_ops,
 108                                  flowi6_to_flowi(fl6), flags, &arg);
 109
 110                 if (res.rt6)
 111                         return &res.rt6->dst;
 112         } else {
 113                 struct rt6_info *rt;
 114
 115                 rt = pol_lookup_func(lookup,
 116                              net, net->ipv6.fib6_local_tbl, fl6, skb, flags);
 117                 if (rt != net->ipv6.ip6_null_entry && rt->dst.error != -EAGAIN)
 118                         return &rt->dst;
 119                 ip6_rt_put_flags(rt, flags);
 120                 rt = pol_lookup_func(lookup,
 121                              net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
 122                 if (rt->dst.error != -EAGAIN)
 123                         return &rt->dst;
 124                 ip6_rt_put_flags(rt, flags);
 125         }
 126
 127         if (!(flags & RT6_LOOKUP_F_DST_NOREF))
 128                 dst_hold(&net->ipv6.ip6_null_entry->dst);
 129         return &net->ipv6.ip6_null_entry->dst;
 130 }
 131
 132 static int fib6_rule_saddr(struct net *net, struct fib_rule *rule, int flags,
 133                            struct flowi6 *flp6, const struct net_device *dev)
 134 {
 135         struct fib6_rule *r = (struct fib6_rule *)rule;
 136
 137         /* If we need to find a source address for this traffic,
 138          * we check the result if it meets requirement of the rule.
 139          */
 140         if ((rule->flags & FIB_RULE_FIND_SADDR) &&
 141             r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
 142                 struct in6_addr saddr;
 143
 144                 if (ipv6_dev_get_saddr(net, dev, &flp6->daddr,
 145                                        rt6_flags2srcprefs(flags), &saddr))
 146                         return -EAGAIN;
 147
 148                 if (!ipv6_prefix_equal(&saddr, &r->src.addr, r->src.plen))
 149                         return -EAGAIN;
 150
 151                 flp6->saddr = saddr;
 152         }
 153
 154         return 0;
 155 }
 156
 157 static int fib6_rule_action_alt(struct fib_rule *rule, struct flowi *flp,
 158                                 int flags, struct fib_lookup_arg *arg)
 159 {
 160         struct fib6_result *res = arg->result;
 161         struct flowi6 *flp6 = &flp->u.ip6;
 162         struct net *net = rule->fr_net;
 163         struct fib6_table *table;
 164         int err, *oif;
 165         u32 tb_id;
 166
 167         switch (rule->action) {
 168         case FR_ACT_TO_TBL:
 169                 break;
 170         case FR_ACT_UNREACHABLE:
 171                 return -ENETUNREACH;
 172         case FR_ACT_PROHIBIT:
 173                 return -EACCES;
 174         case FR_ACT_BLACKHOLE:
 175         default:
 176                 return -EINVAL;
 177         }
 178
 179         tb_id = fib_rule_get_table(rule, arg);
 180         table = fib6_get_table(net, tb_id);
 181         if (!table)
 182                 return -EAGAIN;
 183
 184         oif = (int *)arg->lookup_data;
 185         err = fib6_table_lookup(net, table, *oif, flp6, res, flags);
 186         if (!err && res->f6i != net->ipv6.fib6_null_entry)
 187                 err = fib6_rule_saddr(net, rule, flags, flp6,
 188                                       res->nh->fib_nh_dev);
 189         else
 190                 err = -EAGAIN;
 191
 192         return err;
 193 }
 194
 195 static int __fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
 196                               int flags, struct fib_lookup_arg *arg)
 197 {
 198         struct fib6_result *res = arg->result;
 199         struct flowi6 *flp6 = &flp->u.ip6;
 200         struct rt6_info *rt = NULL;
 201         struct fib6_table *table;
 202         struct net *net = rule->fr_net;
 203         pol_lookup_t lookup = arg->lookup_ptr;
 204         int err = 0;
 205         u32 tb_id;
 206
 207         switch (rule->action) {
 208         case FR_ACT_TO_TBL:
 209                 break;
 210         case FR_ACT_UNREACHABLE:
 211                 err = -ENETUNREACH;
 212                 rt = net->ipv6.ip6_null_entry;
 213                 goto discard_pkt;
 214         default:
 215         case FR_ACT_BLACKHOLE:
 216                 err = -EINVAL;
 217                 rt = net->ipv6.ip6_blk_hole_entry;
 218                 goto discard_pkt;
 219         case FR_ACT_PROHIBIT:
 220                 err = -EACCES;
 221                 rt = net->ipv6.ip6_prohibit_entry;
 222                 goto discard_pkt;
 223         }
 224
 225         tb_id = fib_rule_get_table(rule, arg);
 226         table = fib6_get_table(net, tb_id);
 227         if (!table) {
 228                 err = -EAGAIN;
 229                 goto out;
 230         }
 231
 232         rt = pol_lookup_func(lookup,
 233                              net, table, flp6, arg->lookup_data, flags);
 234         if (rt != net->ipv6.ip6_null_entry) {
 235                 err = fib6_rule_saddr(net, rule, flags, flp6,
 236                                       ip6_dst_idev(&rt->dst)->dev);
 237
 238                 if (err == -EAGAIN)
 239                         goto again;
 240
 241                 err = rt->dst.error;
 242                 if (err != -EAGAIN)
 243                         goto out;
 244         }
 245 again:
 246         ip6_rt_put_flags(rt, flags);
 247         err = -EAGAIN;
 248         rt = NULL;
 249         goto out;
 250
 251 discard_pkt:
 252         if (!(flags & RT6_LOOKUP_F_DST_NOREF))
 253                 dst_hold(&rt->dst);
 254 out:
 255         res->rt6 = rt;
 256         return err;
 257 }
 258
 259 INDIRECT_CALLABLE_SCOPE int fib6_rule_action(struct fib_rule *rule,
 260                                              struct flowi *flp, int flags,
 261                                              struct fib_lookup_arg *arg)
 262 {
 263         if (arg->lookup_ptr == fib6_table_lookup)
 264                 return fib6_rule_action_alt(rule, flp, flags, arg);
 265
 266         return __fib6_rule_action(rule, flp, flags, arg);
 267 }
 268
 269 INDIRECT_CALLABLE_SCOPE bool fib6_rule_suppress(struct fib_rule *rule,
 270                                                 struct fib_lookup_arg *arg)
 271 {
 272         struct fib6_result *res = arg->result;
 273         struct rt6_info *rt = res->rt6;
 274         struct net_device *dev = NULL;
 275
 276         if (!rt)
 277                 return false;
 278
 279         if (rt->rt6i_idev)
 280                 dev = rt->rt6i_idev->dev;
 281
 282         /* do not accept result if the route does
 283          * not meet the required prefix length
 284          */
 285         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
 286                 goto suppress_route;
 287
 288         /* do not accept result if the route uses a device
 289          * belonging to a forbidden interface group
 290          */
 291         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 292                 goto suppress_route;
 293
 294         return false;
 295
 296 suppress_route:
 297         if (!(arg->flags & FIB_LOOKUP_NOREF))
 298                 ip6_rt_put(rt);
 299         return true;
 300 }
 301
 302 INDIRECT_CALLABLE_SCOPE int fib6_rule_match(struct fib_rule *rule,
 303                                             struct flowi *fl, int flags)
 304 {
 305         struct fib6_rule *r = (struct fib6_rule *) rule;
 306         struct flowi6 *fl6 = &fl->u.ip6;
 307
 308         if (r->dst.plen &&
 309             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
 310                 return 0;
 311
 312         /*
 313          * If FIB_RULE_FIND_SADDR is set and we do not have a
 314          * source address for the traffic, we defer check for
 315          * source address.
 316          */
 317         if (r->src.plen) {
 318                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
 319                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
 320                                                r->src.plen))
 321                                 return 0;
 322                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
 323                         return 0;
 324         }
 325
 326         if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
 327                 return 0;
 328
 329         if (rule->ip_proto && (rule->ip_proto != fl6->flowi6_proto))
 330                 return 0;
 331
 332         if (fib_rule_port_range_set(&rule->sport_range) &&
 333             !fib_rule_port_inrange(&rule->sport_range, fl6->fl6_sport))
 334                 return 0;
 335
 336         if (fib_rule_port_range_set(&rule->dport_range) &&
 337             !fib_rule_port_inrange(&rule->dport_range, fl6->fl6_dport))
 338                 return 0;
 339
 340         return 1;
 341 }
 342
 343 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
 344         FRA_GENERIC_POLICY,
 345 };
 346
 347 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 348                                struct fib_rule_hdr *frh,
 349                                struct nlattr **tb,
 350                                struct netlink_ext_ack *extack)
 351 {
 352         int err = -EINVAL;
 353         struct net *net = sock_net(skb->sk);
 354         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 355
 356         if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
 357                 if (rule->table == RT6_TABLE_UNSPEC) {
 358                         NL_SET_ERR_MSG(extack, "Invalid table");
 359                         goto errout;
 360                 }
 361
 362                 if (fib6_new_table(net, rule->table) == NULL) {
 363                         err = -ENOBUFS;
 364                         goto errout;
 365                 }
 366         }
 367
 368         if (frh->src_len)
 369                 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
 370
 371         if (frh->dst_len)
 372                 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
 373
 374         rule6->src.plen = frh->src_len;
 375         rule6->dst.plen = frh->dst_len;
 376         rule6->tclass = frh->tos;
 377
 378         if (fib_rule_requires_fldissect(rule))
 379                 net->ipv6.fib6_rules_require_fldissect++;
 380
 381         net->ipv6.fib6_has_custom_rules = true;
 382         err = 0;
 383 errout:
 384         return err;
 385 }
 386
 387 static int fib6_rule_delete(struct fib_rule *rule)
 388 {
 389         struct net *net = rule->fr_net;
 390
 391         if (net->ipv6.fib6_rules_require_fldissect &&
 392             fib_rule_requires_fldissect(rule))
 393                 net->ipv6.fib6_rules_require_fldissect--;
 394
 395         return 0;
 396 }
 397
 398 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 399                              struct nlattr **tb)
 400 {
 401         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 402
 403         if (frh->src_len && (rule6->src.plen != frh->src_len))
 404                 return 0;
 405
 406         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
 407                 return 0;
 408
 409         if (frh->tos && (rule6->tclass != frh->tos))
 410                 return 0;
 411
 412         if (frh->src_len &&
 413             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
 414                 return 0;
 415
 416         if (frh->dst_len &&
 417             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
 418                 return 0;
 419
 420         return 1;
 421 }
 422
 423 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 424                           struct fib_rule_hdr *frh)
 425 {
 426         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 427
 428         frh->dst_len = rule6->dst.plen;
 429         frh->src_len = rule6->src.plen;
 430         frh->tos = rule6->tclass;
 431
 432         if ((rule6->dst.plen &&
 433              nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
 434             (rule6->src.plen &&
 435              nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
 436                 goto nla_put_failure;
 437         return 0;
 438
 439 nla_put_failure:
 440         return -ENOBUFS;
 441 }
 442
 443 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
 444 {
 445         return nla_total_size(16) /* dst */
 446                + nla_total_size(16); /* src */
 447 }
 448
 449 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
 450         .family                 = AF_INET6,
 451         .rule_size              = sizeof(struct fib6_rule),
 452         .addr_size              = sizeof(struct in6_addr),
 453         .action                 = fib6_rule_action,
 454         .match                  = fib6_rule_match,
 455         .suppress               = fib6_rule_suppress,
 456         .configure              = fib6_rule_configure,
 457         .delete                 = fib6_rule_delete,
 458         .compare                = fib6_rule_compare,
 459         .fill                   = fib6_rule_fill,
 460         .nlmsg_payload          = fib6_rule_nlmsg_payload,
 461         .nlgroup                = RTNLGRP_IPV6_RULE,
 462         .policy                 = fib6_rule_policy,
 463         .owner                  = THIS_MODULE,
 464         .fro_net                = &init_net,
 465 };
 466
 467 static int __net_init fib6_rules_net_init(struct net *net)
 468 {
 469         struct fib_rules_ops *ops;
 470         int err = -ENOMEM;
 471
 472         ops = fib_rules_register(&fib6_rules_ops_template, net);
 473         if (IS_ERR(ops))
 474                 return PTR_ERR(ops);
 475
 476         err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
 477         if (err)
 478                 goto out_fib6_rules_ops;
 479
 480         err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
 481         if (err)
 482                 goto out_fib6_rules_ops;
 483
 484         net->ipv6.fib6_rules_ops = ops;
 485         net->ipv6.fib6_rules_require_fldissect = 0;
 486 out:
 487         return err;
 488
 489 out_fib6_rules_ops:
 490         fib_rules_unregister(ops);
 491         goto out;
 492 }
 493
 494 static void __net_exit fib6_rules_net_exit(struct net *net)
 495 {
 496         rtnl_lock();
 497         fib_rules_unregister(net->ipv6.fib6_rules_ops);
 498         rtnl_unlock();
 499 }
 500
 501 static struct pernet_operations fib6_rules_net_ops = {
 502         .init = fib6_rules_net_init,
 503         .exit = fib6_rules_net_exit,
 504 };
 505
 506 int __init fib6_rules_init(void)
 507 {
 508         return register_pernet_subsys(&fib6_rules_net_ops);
 509 }
 510
 511
 512 void fib6_rules_cleanup(void)
 513 {
 514         unregister_pernet_subsys(&fib6_rules_net_ops);
 515 }