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/inet_dscp.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         dscp_t                  dscp;
  30         u8                      dscp_full:1;    /* DSCP or TOS selector */
  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->dscp)
  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                     struct netlink_ext_ack *extack)
  55 {
  56         return fib_rules_dump(net, nb, AF_INET6, extack);
  57 }
  58
  59 unsigned int fib6_rules_seq_read(const struct net *net)
  60 {
  61         return fib_rules_seq_read(net, AF_INET6);
  62 }
  63
  64 /* called with rcu lock held; no reference taken on fib6_info */
  65 int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
  66                 struct fib6_result *res, int flags)
  67 {
  68         int err;
  69
  70         if (net->ipv6.fib6_has_custom_rules) {
  71                 struct fib_lookup_arg arg = {
  72                         .lookup_ptr = fib6_table_lookup,
  73                         .lookup_data = &oif,
  74                         .result = res,
  75                         .flags = FIB_LOOKUP_NOREF,
  76                 };
  77
  78                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
  79
  80                 err = fib_rules_lookup(net->ipv6.fib6_rules_ops,
  81                                        flowi6_to_flowi(fl6), flags, &arg);
  82         } else {
  83                 err = fib6_table_lookup(net, net->ipv6.fib6_local_tbl, oif,
  84                                         fl6, res, flags);
  85                 if (err || res->f6i == net->ipv6.fib6_null_entry)
  86                         err = fib6_table_lookup(net, net->ipv6.fib6_main_tbl,
  87                                                 oif, fl6, res, flags);
  88         }
  89
  90         return err;
  91 }
  92
  93 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
  94                                    const struct sk_buff *skb,
  95                                    int flags, pol_lookup_t lookup)
  96 {
  97         if (net->ipv6.fib6_has_custom_rules) {
  98                 struct fib6_result res = {};
  99                 struct fib_lookup_arg arg = {
 100                         .lookup_ptr = lookup,
 101                         .lookup_data = skb,
 102                         .result = &res,
 103                         .flags = FIB_LOOKUP_NOREF,
 104                 };
 105
 106                 /* update flow if oif or iif point to device enslaved to l3mdev */
 107                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
 108
 109                 fib_rules_lookup(net->ipv6.fib6_rules_ops,
 110                                  flowi6_to_flowi(fl6), flags, &arg);
 111
 112                 if (res.rt6)
 113                         return &res.rt6->dst;
 114         } else {
 115                 struct rt6_info *rt;
 116
 117                 rt = pol_lookup_func(lookup,
 118                              net, net->ipv6.fib6_local_tbl, fl6, skb, flags);
 119                 if (rt != net->ipv6.ip6_null_entry && rt->dst.error != -EAGAIN)
 120                         return &rt->dst;
 121                 ip6_rt_put_flags(rt, flags);
 122                 rt = pol_lookup_func(lookup,
 123                              net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
 124                 if (rt->dst.error != -EAGAIN)
 125                         return &rt->dst;
 126                 ip6_rt_put_flags(rt, flags);
 127         }
 128
 129         if (!(flags & RT6_LOOKUP_F_DST_NOREF))
 130                 dst_hold(&net->ipv6.ip6_null_entry->dst);
 131         return &net->ipv6.ip6_null_entry->dst;
 132 }
 133
 134 static int fib6_rule_saddr(struct net *net, struct fib_rule *rule, int flags,
 135                            struct flowi6 *flp6, const struct net_device *dev)
 136 {
 137         struct fib6_rule *r = (struct fib6_rule *)rule;
 138
 139         /* If we need to find a source address for this traffic,
 140          * we check the result if it meets requirement of the rule.
 141          */
 142         if ((rule->flags & FIB_RULE_FIND_SADDR) &&
 143             r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
 144                 struct in6_addr saddr;
 145
 146                 if (ipv6_dev_get_saddr(net, dev, &flp6->daddr,
 147                                        rt6_flags2srcprefs(flags), &saddr))
 148                         return -EAGAIN;
 149
 150                 if (!ipv6_prefix_equal(&saddr, &r->src.addr, r->src.plen))
 151                         return -EAGAIN;
 152
 153                 flp6->saddr = saddr;
 154         }
 155
 156         return 0;
 157 }
 158
 159 static int fib6_rule_action_alt(struct fib_rule *rule, struct flowi *flp,
 160                                 int flags, struct fib_lookup_arg *arg)
 161 {
 162         struct fib6_result *res = arg->result;
 163         struct flowi6 *flp6 = &flp->u.ip6;
 164         struct net *net = rule->fr_net;
 165         struct fib6_table *table;
 166         int err, *oif;
 167         u32 tb_id;
 168
 169         switch (rule->action) {
 170         case FR_ACT_TO_TBL:
 171                 break;
 172         case FR_ACT_UNREACHABLE:
 173                 return -ENETUNREACH;
 174         case FR_ACT_PROHIBIT:
 175                 return -EACCES;
 176         case FR_ACT_BLACKHOLE:
 177         default:
 178                 return -EINVAL;
 179         }
 180
 181         tb_id = fib_rule_get_table(rule, arg);
 182         table = fib6_get_table(net, tb_id);
 183         if (!table)
 184                 return -EAGAIN;
 185
 186         oif = (int *)arg->lookup_data;
 187         err = fib6_table_lookup(net, table, *oif, flp6, res, flags);
 188         if (!err && res->f6i != net->ipv6.fib6_null_entry)
 189                 err = fib6_rule_saddr(net, rule, flags, flp6,
 190                                       res->nh->fib_nh_dev);
 191         else
 192                 err = -EAGAIN;
 193
 194         return err;
 195 }
 196
 197 static int __fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
 198                               int flags, struct fib_lookup_arg *arg)
 199 {
 200         struct fib6_result *res = arg->result;
 201         struct flowi6 *flp6 = &flp->u.ip6;
 202         struct rt6_info *rt = NULL;
 203         struct fib6_table *table;
 204         struct net *net = rule->fr_net;
 205         pol_lookup_t lookup = arg->lookup_ptr;
 206         int err = 0;
 207         u32 tb_id;
 208
 209         switch (rule->action) {
 210         case FR_ACT_TO_TBL:
 211                 break;
 212         case FR_ACT_UNREACHABLE:
 213                 err = -ENETUNREACH;
 214                 rt = net->ipv6.ip6_null_entry;
 215                 goto discard_pkt;
 216         default:
 217         case FR_ACT_BLACKHOLE:
 218                 err = -EINVAL;
 219                 rt = net->ipv6.ip6_blk_hole_entry;
 220                 goto discard_pkt;
 221         case FR_ACT_PROHIBIT:
 222                 err = -EACCES;
 223                 rt = net->ipv6.ip6_prohibit_entry;
 224                 goto discard_pkt;
 225         }
 226
 227         tb_id = fib_rule_get_table(rule, arg);
 228         table = fib6_get_table(net, tb_id);
 229         if (!table) {
 230                 err = -EAGAIN;
 231                 goto out;
 232         }
 233
 234         rt = pol_lookup_func(lookup,
 235                              net, table, flp6, arg->lookup_data, flags);
 236         if (rt != net->ipv6.ip6_null_entry) {
 237                 struct inet6_dev *idev = ip6_dst_idev(&rt->dst);
 238
 239                 if (!idev)
 240                         goto again;
 241                 err = fib6_rule_saddr(net, rule, flags, flp6,
 242                                       idev->dev);
 243
 244                 if (err == -EAGAIN)
 245                         goto again;
 246
 247                 err = rt->dst.error;
 248                 if (err != -EAGAIN)
 249                         goto out;
 250         }
 251 again:
 252         ip6_rt_put_flags(rt, flags);
 253         err = -EAGAIN;
 254         rt = NULL;
 255         goto out;
 256
 257 discard_pkt:
 258         if (!(flags & RT6_LOOKUP_F_DST_NOREF))
 259                 dst_hold(&rt->dst);
 260 out:
 261         res->rt6 = rt;
 262         return err;
 263 }
 264
 265 INDIRECT_CALLABLE_SCOPE int fib6_rule_action(struct fib_rule *rule,
 266                                              struct flowi *flp, int flags,
 267                                              struct fib_lookup_arg *arg)
 268 {
 269         if (arg->lookup_ptr == fib6_table_lookup)
 270                 return fib6_rule_action_alt(rule, flp, flags, arg);
 271
 272         return __fib6_rule_action(rule, flp, flags, arg);
 273 }
 274
 275 INDIRECT_CALLABLE_SCOPE bool fib6_rule_suppress(struct fib_rule *rule,
 276                                                 int flags,
 277                                                 struct fib_lookup_arg *arg)
 278 {
 279         struct fib6_result *res = arg->result;
 280         struct rt6_info *rt = res->rt6;
 281         struct net_device *dev = NULL;
 282
 283         if (!rt)
 284                 return false;
 285
 286         if (rt->rt6i_idev)
 287                 dev = rt->rt6i_idev->dev;
 288
 289         /* do not accept result if the route does
 290          * not meet the required prefix length
 291          */
 292         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
 293                 goto suppress_route;
 294
 295         /* do not accept result if the route uses a device
 296          * belonging to a forbidden interface group
 297          */
 298         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 299                 goto suppress_route;
 300
 301         return false;
 302
 303 suppress_route:
 304         ip6_rt_put_flags(rt, flags);
 305         return true;
 306 }
 307
 308 INDIRECT_CALLABLE_SCOPE int fib6_rule_match(struct fib_rule *rule,
 309                                             struct flowi *fl, int flags)
 310 {
 311         struct fib6_rule *r = (struct fib6_rule *) rule;
 312         struct flowi6 *fl6 = &fl->u.ip6;
 313
 314         if (r->dst.plen &&
 315             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
 316                 return 0;
 317
 318         /*
 319          * If FIB_RULE_FIND_SADDR is set and we do not have a
 320          * source address for the traffic, we defer check for
 321          * source address.
 322          */
 323         if (r->src.plen) {
 324                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
 325                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
 326                                                r->src.plen))
 327                                 return 0;
 328                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
 329                         return 0;
 330         }
 331
 332         if (r->dscp && r->dscp != ip6_dscp(fl6->flowlabel))
 333                 return 0;
 334
 335         if (rule->ip_proto && (rule->ip_proto != fl6->flowi6_proto))
 336                 return 0;
 337
 338         if (fib_rule_port_range_set(&rule->sport_range) &&
 339             !fib_rule_port_inrange(&rule->sport_range, fl6->fl6_sport))
 340                 return 0;
 341
 342         if (fib_rule_port_range_set(&rule->dport_range) &&
 343             !fib_rule_port_inrange(&rule->dport_range, fl6->fl6_dport))
 344                 return 0;
 345
 346         return 1;
 347 }
 348
 349 static int fib6_nl2rule_dscp(const struct nlattr *nla, struct fib6_rule *rule6,
 350                              struct netlink_ext_ack *extack)
 351 {
 352         if (rule6->dscp) {
 353                 NL_SET_ERR_MSG(extack, "Cannot specify both TOS and DSCP");
 354                 return -EINVAL;
 355         }
 356
 357         rule6->dscp = inet_dsfield_to_dscp(nla_get_u8(nla) << 2);
 358         rule6->dscp_full = true;
 359
 360         return 0;
 361 }
 362
 363 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 364                                struct fib_rule_hdr *frh,
 365                                struct nlattr **tb,
 366                                struct netlink_ext_ack *extack)
 367 {
 368         int err = -EINVAL;
 369         struct net *net = sock_net(skb->sk);
 370         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 371
 372         if (!inet_validate_dscp(frh->tos)) {
 373                 NL_SET_ERR_MSG(extack,
 374                                "Invalid dsfield (tos): ECN bits must be 0");
 375                 goto errout;
 376         }
 377         rule6->dscp = inet_dsfield_to_dscp(frh->tos);
 378
 379         if (tb[FRA_DSCP] && fib6_nl2rule_dscp(tb[FRA_DSCP], rule6, extack) < 0)
 380                 goto errout;
 381
 382         if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
 383                 if (rule->table == RT6_TABLE_UNSPEC) {
 384                         NL_SET_ERR_MSG(extack, "Invalid table");
 385                         goto errout;
 386                 }
 387
 388                 if (fib6_new_table(net, rule->table) == NULL) {
 389                         err = -ENOBUFS;
 390                         goto errout;
 391                 }
 392         }
 393
 394         if (frh->src_len)
 395                 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
 396
 397         if (frh->dst_len)
 398                 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
 399
 400         rule6->src.plen = frh->src_len;
 401         rule6->dst.plen = frh->dst_len;
 402
 403         if (fib_rule_requires_fldissect(rule))
 404                 net->ipv6.fib6_rules_require_fldissect++;
 405
 406         net->ipv6.fib6_has_custom_rules = true;
 407         err = 0;
 408 errout:
 409         return err;
 410 }
 411
 412 static int fib6_rule_delete(struct fib_rule *rule)
 413 {
 414         struct net *net = rule->fr_net;
 415
 416         if (net->ipv6.fib6_rules_require_fldissect &&
 417             fib_rule_requires_fldissect(rule))
 418                 net->ipv6.fib6_rules_require_fldissect--;
 419
 420         return 0;
 421 }
 422
 423 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 424                              struct nlattr **tb)
 425 {
 426         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 427
 428         if (frh->src_len && (rule6->src.plen != frh->src_len))
 429                 return 0;
 430
 431         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
 432                 return 0;
 433
 434         if (frh->tos &&
 435             (rule6->dscp_full ||
 436              inet_dscp_to_dsfield(rule6->dscp) != frh->tos))
 437                 return 0;
 438
 439         if (tb[FRA_DSCP]) {
 440                 dscp_t dscp;
 441
 442                 dscp = inet_dsfield_to_dscp(nla_get_u8(tb[FRA_DSCP]) << 2);
 443                 if (!rule6->dscp_full || rule6->dscp != dscp)
 444                         return 0;
 445         }
 446
 447         if (frh->src_len &&
 448             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
 449                 return 0;
 450
 451         if (frh->dst_len &&
 452             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
 453                 return 0;
 454
 455         return 1;
 456 }
 457
 458 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 459                           struct fib_rule_hdr *frh)
 460 {
 461         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 462
 463         frh->dst_len = rule6->dst.plen;
 464         frh->src_len = rule6->src.plen;
 465
 466         if (rule6->dscp_full) {
 467                 frh->tos = 0;
 468                 if (nla_put_u8(skb, FRA_DSCP,
 469                                inet_dscp_to_dsfield(rule6->dscp) >> 2))
 470                         goto nla_put_failure;
 471         } else {
 472                 frh->tos = inet_dscp_to_dsfield(rule6->dscp);
 473         }
 474
 475         if ((rule6->dst.plen &&
 476              nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
 477             (rule6->src.plen &&
 478              nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
 479                 goto nla_put_failure;
 480         return 0;
 481
 482 nla_put_failure:
 483         return -ENOBUFS;
 484 }
 485
 486 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
 487 {
 488         return nla_total_size(16) /* dst */
 489                + nla_total_size(16) /* src */
 490                + nla_total_size(1); /* dscp */
 491 }
 492
 493 static void fib6_rule_flush_cache(struct fib_rules_ops *ops)
 494 {
 495         rt_genid_bump_ipv6(ops->fro_net);
 496 }
 497
 498 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
 499         .family                 = AF_INET6,
 500         .rule_size              = sizeof(struct fib6_rule),
 501         .addr_size              = sizeof(struct in6_addr),
 502         .action                 = fib6_rule_action,
 503         .match                  = fib6_rule_match,
 504         .suppress               = fib6_rule_suppress,
 505         .configure              = fib6_rule_configure,
 506         .delete                 = fib6_rule_delete,
 507         .compare                = fib6_rule_compare,
 508         .fill                   = fib6_rule_fill,
 509         .nlmsg_payload          = fib6_rule_nlmsg_payload,
 510         .flush_cache            = fib6_rule_flush_cache,
 511         .nlgroup                = RTNLGRP_IPV6_RULE,
 512         .owner                  = THIS_MODULE,
 513         .fro_net                = &init_net,
 514 };
 515
 516 static int __net_init fib6_rules_net_init(struct net *net)
 517 {
 518         struct fib_rules_ops *ops;
 519         int err;
 520
 521         ops = fib_rules_register(&fib6_rules_ops_template, net);
 522         if (IS_ERR(ops))
 523                 return PTR_ERR(ops);
 524
 525         err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL);
 526         if (err)
 527                 goto out_fib6_rules_ops;
 528
 529         err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN);
 530         if (err)
 531                 goto out_fib6_rules_ops;
 532
 533         net->ipv6.fib6_rules_ops = ops;
 534         net->ipv6.fib6_rules_require_fldissect = 0;
 535 out:
 536         return err;
 537
 538 out_fib6_rules_ops:
 539         fib_rules_unregister(ops);
 540         goto out;
 541 }
 542
 543 static void __net_exit fib6_rules_net_exit_batch(struct list_head *net_list)
 544 {
 545         struct net *net;
 546
 547         rtnl_lock();
 548         list_for_each_entry(net, net_list, exit_list) {
 549                 fib_rules_unregister(net->ipv6.fib6_rules_ops);
 550                 cond_resched();
 551         }
 552         rtnl_unlock();
 553 }
 554
 555 static struct pernet_operations fib6_rules_net_ops = {
 556         .init = fib6_rules_net_init,
 557         .exit_batch = fib6_rules_net_exit_batch,
 558 };
 559
 560 int __init fib6_rules_init(void)
 561 {
 562         return register_pernet_subsys(&fib6_rules_net_ops);
 563 }
 564
 565
 566 void fib6_rules_cleanup(void)
 567 {
 568         unregister_pernet_subsys(&fib6_rules_net_ops);
 569 }