net/ipv4/fib_rules.c

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