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         return 1;
 186 }
 187
 188 static struct fib_table *fib_empty_table(struct net *net)
 189 {
 190         u32 id;
 191
 192         for (id = 1; id <= RT_TABLE_MAX; id++)
 193                 if (!fib_get_table(net, id))
 194                         return fib_new_table(net, id);
 195         return NULL;
 196 }
 197
 198 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 199         FRA_GENERIC_POLICY,
 200         [FRA_FLOW]      = { .type = NLA_U32 },
 201 };
 202
 203 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 204                                struct fib_rule_hdr *frh,
 205                                struct nlattr **tb)
 206 {
 207         struct net *net = sock_net(skb->sk);
 208         int err = -EINVAL;
 209         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 210
 211         if (frh->tos & ~IPTOS_TOS_MASK)
 212                 goto errout;
 213
 214         /* split local/main if they are not already split */
 215         err = fib_unmerge(net);
 216         if (err)
 217                 goto errout;
 218
 219         if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {
 220                 if (rule->action == FR_ACT_TO_TBL) {
 221                         struct fib_table *table;
 222
 223                         table = fib_empty_table(net);
 224                         if (!table) {
 225                                 err = -ENOBUFS;
 226                                 goto errout;
 227                         }
 228
 229                         rule->table = table->tb_id;
 230                 }
 231         }
 232
 233         if (frh->src_len)
 234                 rule4->src = nla_get_in_addr(tb[FRA_SRC]);
 235
 236         if (frh->dst_len)
 237                 rule4->dst = nla_get_in_addr(tb[FRA_DST]);
 238
 239 #ifdef CONFIG_IP_ROUTE_CLASSID
 240         if (tb[FRA_FLOW]) {
 241                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 242                 if (rule4->tclassid)
 243                         net->ipv4.fib_num_tclassid_users++;
 244         }
 245 #endif
 246
 247         rule4->src_len = frh->src_len;
 248         rule4->srcmask = inet_make_mask(rule4->src_len);
 249         rule4->dst_len = frh->dst_len;
 250         rule4->dstmask = inet_make_mask(rule4->dst_len);
 251         rule4->tos = frh->tos;
 252
 253         net->ipv4.fib_has_custom_rules = true;
 254
 255         err = 0;
 256 errout:
 257         return err;
 258 }
 259
 260 static int fib4_rule_delete(struct fib_rule *rule)
 261 {
 262         struct net *net = rule->fr_net;
 263         int err;
 264
 265         /* split local/main if they are not already split */
 266         err = fib_unmerge(net);
 267         if (err)
 268                 goto errout;
 269
 270 #ifdef CONFIG_IP_ROUTE_CLASSID
 271         if (((struct fib4_rule *)rule)->tclassid)
 272                 net->ipv4.fib_num_tclassid_users--;
 273 #endif
 274         net->ipv4.fib_has_custom_rules = true;
 275 errout:
 276         return err;
 277 }
 278
 279 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 280                              struct nlattr **tb)
 281 {
 282         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 283
 284         if (frh->src_len && (rule4->src_len != frh->src_len))
 285                 return 0;
 286
 287         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 288                 return 0;
 289
 290         if (frh->tos && (rule4->tos != frh->tos))
 291                 return 0;
 292
 293 #ifdef CONFIG_IP_ROUTE_CLASSID
 294         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 295                 return 0;
 296 #endif
 297
 298         if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
 299                 return 0;
 300
 301         if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
 302                 return 0;
 303
 304         return 1;
 305 }
 306
 307 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 308                           struct fib_rule_hdr *frh)
 309 {
 310         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 311
 312         frh->dst_len = rule4->dst_len;
 313         frh->src_len = rule4->src_len;
 314         frh->tos = rule4->tos;
 315
 316         if ((rule4->dst_len &&
 317              nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
 318             (rule4->src_len &&
 319              nla_put_in_addr(skb, FRA_SRC, rule4->src)))
 320                 goto nla_put_failure;
 321 #ifdef CONFIG_IP_ROUTE_CLASSID
 322         if (rule4->tclassid &&
 323             nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
 324                 goto nla_put_failure;
 325 #endif
 326         return 0;
 327
 328 nla_put_failure:
 329         return -ENOBUFS;
 330 }
 331
 332 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 333 {
 334         return nla_total_size(4) /* dst */
 335                + nla_total_size(4) /* src */
 336                + nla_total_size(4); /* flow */
 337 }
 338
 339 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 340 {
 341         rt_cache_flush(ops->fro_net);
 342 }
 343
 344 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
 345         .family         = AF_INET,
 346         .rule_size      = sizeof(struct fib4_rule),
 347         .addr_size      = sizeof(u32),
 348         .action         = fib4_rule_action,
 349         .suppress       = fib4_rule_suppress,
 350         .match          = fib4_rule_match,
 351         .configure      = fib4_rule_configure,
 352         .delete         = fib4_rule_delete,
 353         .compare        = fib4_rule_compare,
 354         .fill           = fib4_rule_fill,
 355         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 356         .flush_cache    = fib4_rule_flush_cache,
 357         .nlgroup        = RTNLGRP_IPV4_RULE,
 358         .policy         = fib4_rule_policy,
 359         .owner          = THIS_MODULE,
 360 };
 361
 362 static int fib_default_rules_init(struct fib_rules_ops *ops)
 363 {
 364         int err;
 365
 366         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 367         if (err < 0)
 368                 return err;
 369         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 370         if (err < 0)
 371                 return err;
 372         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 373         if (err < 0)
 374                 return err;
 375         return 0;
 376 }
 377
 378 int __net_init fib4_rules_init(struct net *net)
 379 {
 380         int err;
 381         struct fib_rules_ops *ops;
 382
 383         ops = fib_rules_register(&fib4_rules_ops_template, net);
 384         if (IS_ERR(ops))
 385                 return PTR_ERR(ops);
 386
 387         err = fib_default_rules_init(ops);
 388         if (err < 0)
 389                 goto fail;
 390         net->ipv4.rules_ops = ops;
 391         net->ipv4.fib_has_custom_rules = false;
 392         return 0;
 393
 394 fail:
 395         /* also cleans all rules already added */
 396         fib_rules_unregister(ops);
 397         return err;
 398 }
 399
 400 void __net_exit fib4_rules_exit(struct net *net)
 401 {
 402         fib_rules_unregister(net->ipv4.rules_ops);
 403 }