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