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