net/ipv4/fib_rules.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              IPv4 Forwarding Information Base: policy rules.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *              Thomas Graf <tgraf@suug.ch>
  11  *
  12  * Fixes:
  13  *              Rani Assaf      :       local_rule cannot be deleted
  14  *              Marc Boucher    :       routing by fwmark
  15  */
  16
  17 #include <linux/types.h>
  18 #include <linux/kernel.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/netlink.h>
  21 #include <linux/inetdevice.h>
  22 #include <linux/init.h>
  23 #include <linux/list.h>
  24 #include <linux/rcupdate.h>
  25 #include <linux/export.h>
  26 #include <net/ip.h>
  27 #include <net/route.h>
  28 #include <net/tcp.h>
  29 #include <net/ip_fib.h>
  30 #include <net/nexthop.h>
  31 #include <net/fib_rules.h>
  32 #include <linux/indirect_call_wrapper.h>
  33
  34 struct fib4_rule {
  35         struct fib_rule         common;
  36         u8                      dst_len;
  37         u8                      src_len;
  38         u8                      tos;
  39         __be32                  src;
  40         __be32                  srcmask;
  41         __be32                  dst;
  42         __be32                  dstmask;
  43 #ifdef CONFIG_IP_ROUTE_CLASSID
  44         u32                     tclassid;
  45 #endif
  46 };
  47
  48 static bool fib4_rule_matchall(const struct fib_rule *rule)
  49 {
  50         struct fib4_rule *r = container_of(rule, struct fib4_rule, common);
  51
  52         if (r->dst_len || r->src_len || r->tos)
  53                 return false;
  54         return fib_rule_matchall(rule);
  55 }
  56
  57 bool fib4_rule_default(const struct fib_rule *rule)
  58 {
  59         if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
  60             rule->l3mdev)
  61                 return false;
  62         if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN &&
  63             rule->table != RT_TABLE_DEFAULT)
  64                 return false;
  65         return true;
  66 }
  67 EXPORT_SYMBOL_GPL(fib4_rule_default);
  68
  69 int fib4_rules_dump(struct net *net, struct notifier_block *nb,
  70                     struct netlink_ext_ack *extack)
  71 {
  72         return fib_rules_dump(net, nb, AF_INET, extack);
  73 }
  74
  75 unsigned int fib4_rules_seq_read(struct net *net)
  76 {
  77         return fib_rules_seq_read(net, AF_INET);
  78 }
  79
  80 int __fib_lookup(struct net *net, struct flowi4 *flp,
  81                  struct fib_result *res, unsigned int flags)
  82 {
  83         struct fib_lookup_arg arg = {
  84                 .result = res,
  85                 .flags = flags,
  86         };
  87         int err;
  88
  89         /* update flow if oif or iif point to device enslaved to l3mdev */
  90         l3mdev_update_flow(net, flowi4_to_flowi(flp));
  91
  92         err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
  93 #ifdef CONFIG_IP_ROUTE_CLASSID
  94         if (arg.rule)
  95                 res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
  96         else
  97                 res->tclassid = 0;
  98 #endif
  99
 100         if (err == -ESRCH)
 101                 err = -ENETUNREACH;
 102
 103         return err;
 104 }
 105 EXPORT_SYMBOL_GPL(__fib_lookup);
 106
 107 INDIRECT_CALLABLE_SCOPE int fib4_rule_action(struct fib_rule *rule,
 108                                              struct flowi *flp, int flags,
 109                                              struct fib_lookup_arg *arg)
 110 {
 111         int err = -EAGAIN;
 112         struct fib_table *tbl;
 113         u32 tb_id;
 114
 115         switch (rule->action) {
 116         case FR_ACT_TO_TBL:
 117                 break;
 118
 119         case FR_ACT_UNREACHABLE:
 120                 return -ENETUNREACH;
 121
 122         case FR_ACT_PROHIBIT:
 123                 return -EACCES;
 124
 125         case FR_ACT_BLACKHOLE:
 126         default:
 127                 return -EINVAL;
 128         }
 129
 130         rcu_read_lock();
 131
 132         tb_id = fib_rule_get_table(rule, arg);
 133         tbl = fib_get_table(rule->fr_net, tb_id);
 134         if (tbl)
 135                 err = fib_table_lookup(tbl, &flp->u.ip4,
 136                                        (struct fib_result *)arg->result,
 137                                        arg->flags);
 138
 139         rcu_read_unlock();
 140         return err;
 141 }
 142
 143 INDIRECT_CALLABLE_SCOPE bool fib4_rule_suppress(struct fib_rule *rule,
 144                                                 struct fib_lookup_arg *arg)
 145 {
 146         struct fib_result *result = (struct fib_result *) arg->result;
 147         struct net_device *dev = NULL;
 148
 149         if (result->fi) {
 150                 struct fib_nh_common *nhc = fib_info_nhc(result->fi, 0);
 151
 152                 dev = nhc->nhc_dev;
 153         }
 154
 155         /* do not accept result if the route does
 156          * not meet the required prefix length
 157          */
 158         if (result->prefixlen <= rule->suppress_prefixlen)
 159                 goto suppress_route;
 160
 161         /* do not accept result if the route uses a device
 162          * belonging to a forbidden interface group
 163          */
 164         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 165                 goto suppress_route;
 166
 167         return false;
 168
 169 suppress_route:
 170         if (!(arg->flags & FIB_LOOKUP_NOREF))
 171                 fib_info_put(result->fi);
 172         return true;
 173 }
 174
 175 INDIRECT_CALLABLE_SCOPE int fib4_rule_match(struct fib_rule *rule,
 176                                             struct flowi *fl, int flags)
 177 {
 178         struct fib4_rule *r = (struct fib4_rule *) rule;
 179         struct flowi4 *fl4 = &fl->u.ip4;
 180         __be32 daddr = fl4->daddr;
 181         __be32 saddr = fl4->saddr;
 182
 183         if (((saddr ^ r->src) & r->srcmask) ||
 184             ((daddr ^ r->dst) & r->dstmask))
 185                 return 0;
 186
 187         if (r->tos && (r->tos != fl4->flowi4_tos))
 188                 return 0;
 189
 190         if (rule->ip_proto && (rule->ip_proto != fl4->flowi4_proto))
 191                 return 0;
 192
 193         if (fib_rule_port_range_set(&rule->sport_range) &&
 194             !fib_rule_port_inrange(&rule->sport_range, fl4->fl4_sport))
 195                 return 0;
 196
 197         if (fib_rule_port_range_set(&rule->dport_range) &&
 198             !fib_rule_port_inrange(&rule->dport_range, fl4->fl4_dport))
 199                 return 0;
 200
 201         return 1;
 202 }
 203
 204 static struct fib_table *fib_empty_table(struct net *net)
 205 {
 206         u32 id = 1;
 207
 208         while (1) {
 209                 if (!fib_get_table(net, id))
 210                         return fib_new_table(net, id);
 211
 212                 if (id++ == RT_TABLE_MAX)
 213                         break;
 214         }
 215         return NULL;
 216 }
 217
 218 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 219         FRA_GENERIC_POLICY,
 220         [FRA_FLOW]      = { .type = NLA_U32 },
 221 };
 222
 223 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 224                                struct fib_rule_hdr *frh,
 225                                struct nlattr **tb,
 226                                struct netlink_ext_ack *extack)
 227 {
 228         struct net *net = sock_net(skb->sk);
 229         int err = -EINVAL;
 230         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 231
 232         if (frh->tos & ~IPTOS_TOS_MASK) {
 233                 NL_SET_ERR_MSG(extack, "Invalid tos");
 234                 goto errout;
 235         }
 236
 237         /* split local/main if they are not already split */
 238         err = fib_unmerge(net);
 239         if (err)
 240                 goto errout;
 241
 242         if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {
 243                 if (rule->action == FR_ACT_TO_TBL) {
 244                         struct fib_table *table;
 245
 246                         table = fib_empty_table(net);
 247                         if (!table) {
 248                                 err = -ENOBUFS;
 249                                 goto errout;
 250                         }
 251
 252                         rule->table = table->tb_id;
 253                 }
 254         }
 255
 256         if (frh->src_len)
 257                 rule4->src = nla_get_in_addr(tb[FRA_SRC]);
 258
 259         if (frh->dst_len)
 260                 rule4->dst = nla_get_in_addr(tb[FRA_DST]);
 261
 262 #ifdef CONFIG_IP_ROUTE_CLASSID
 263         if (tb[FRA_FLOW]) {
 264                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 265                 if (rule4->tclassid)
 266                         net->ipv4.fib_num_tclassid_users++;
 267         }
 268 #endif
 269
 270         if (fib_rule_requires_fldissect(rule))
 271                 net->ipv4.fib_rules_require_fldissect++;
 272
 273         rule4->src_len = frh->src_len;
 274         rule4->srcmask = inet_make_mask(rule4->src_len);
 275         rule4->dst_len = frh->dst_len;
 276         rule4->dstmask = inet_make_mask(rule4->dst_len);
 277         rule4->tos = frh->tos;
 278
 279         net->ipv4.fib_has_custom_rules = true;
 280
 281         err = 0;
 282 errout:
 283         return err;
 284 }
 285
 286 static int fib4_rule_delete(struct fib_rule *rule)
 287 {
 288         struct net *net = rule->fr_net;
 289         int err;
 290
 291         /* split local/main if they are not already split */
 292         err = fib_unmerge(net);
 293         if (err)
 294                 goto errout;
 295
 296 #ifdef CONFIG_IP_ROUTE_CLASSID
 297         if (((struct fib4_rule *)rule)->tclassid)
 298                 net->ipv4.fib_num_tclassid_users--;
 299 #endif
 300         net->ipv4.fib_has_custom_rules = true;
 301
 302         if (net->ipv4.fib_rules_require_fldissect &&
 303             fib_rule_requires_fldissect(rule))
 304                 net->ipv4.fib_rules_require_fldissect--;
 305 errout:
 306         return err;
 307 }
 308
 309 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 310                              struct nlattr **tb)
 311 {
 312         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 313
 314         if (frh->src_len && (rule4->src_len != frh->src_len))
 315                 return 0;
 316
 317         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 318                 return 0;
 319
 320         if (frh->tos && (rule4->tos != frh->tos))
 321                 return 0;
 322
 323 #ifdef CONFIG_IP_ROUTE_CLASSID
 324         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 325                 return 0;
 326 #endif
 327
 328         if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
 329                 return 0;
 330
 331         if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
 332                 return 0;
 333
 334         return 1;
 335 }
 336
 337 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 338                           struct fib_rule_hdr *frh)
 339 {
 340         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 341
 342         frh->dst_len = rule4->dst_len;
 343         frh->src_len = rule4->src_len;
 344         frh->tos = rule4->tos;
 345
 346         if ((rule4->dst_len &&
 347              nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
 348             (rule4->src_len &&
 349              nla_put_in_addr(skb, FRA_SRC, rule4->src)))
 350                 goto nla_put_failure;
 351 #ifdef CONFIG_IP_ROUTE_CLASSID
 352         if (rule4->tclassid &&
 353             nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
 354                 goto nla_put_failure;
 355 #endif
 356         return 0;
 357
 358 nla_put_failure:
 359         return -ENOBUFS;
 360 }
 361
 362 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 363 {
 364         return nla_total_size(4) /* dst */
 365                + nla_total_size(4) /* src */
 366                + nla_total_size(4); /* flow */
 367 }
 368
 369 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 370 {
 371         rt_cache_flush(ops->fro_net);
 372 }
 373
 374 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
 375         .family         = AF_INET,
 376         .rule_size      = sizeof(struct fib4_rule),
 377         .addr_size      = sizeof(u32),
 378         .action         = fib4_rule_action,
 379         .suppress       = fib4_rule_suppress,
 380         .match          = fib4_rule_match,
 381         .configure      = fib4_rule_configure,
 382         .delete         = fib4_rule_delete,
 383         .compare        = fib4_rule_compare,
 384         .fill           = fib4_rule_fill,
 385         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 386         .flush_cache    = fib4_rule_flush_cache,
 387         .nlgroup        = RTNLGRP_IPV4_RULE,
 388         .policy         = fib4_rule_policy,
 389         .owner          = THIS_MODULE,
 390 };
 391
 392 static int fib_default_rules_init(struct fib_rules_ops *ops)
 393 {
 394         int err;
 395
 396         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 397         if (err < 0)
 398                 return err;
 399         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 400         if (err < 0)
 401                 return err;
 402         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 403         if (err < 0)
 404                 return err;
 405         return 0;
 406 }
 407
 408 int __net_init fib4_rules_init(struct net *net)
 409 {
 410         int err;
 411         struct fib_rules_ops *ops;
 412
 413         ops = fib_rules_register(&fib4_rules_ops_template, net);
 414         if (IS_ERR(ops))
 415                 return PTR_ERR(ops);
 416
 417         err = fib_default_rules_init(ops);
 418         if (err < 0)
 419                 goto fail;
 420         net->ipv4.rules_ops = ops;
 421         net->ipv4.fib_has_custom_rules = false;
 422         net->ipv4.fib_rules_require_fldissect = 0;
 423         return 0;
 424
 425 fail:
 426         /* also cleans all rules already added */
 427         fib_rules_unregister(ops);
 428         return err;
 429 }
 430
 431 void __net_exit fib4_rules_exit(struct net *net)
 432 {
 433         fib_rules_unregister(net->ipv4.rules_ops);
 434 }