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 int __fib_lookup(struct net *net, struct flowi4 *flp,
  51                  struct fib_result *res, unsigned int flags)
  52 {
  53         struct fib_lookup_arg arg = {
  54                 .result = res,
  55                 .flags = flags,
  56         };
  57         int err;
  58
  59         /* update flow if oif or iif point to device enslaved to l3mdev */
  60         l3mdev_update_flow(net, flowi4_to_flowi(flp));
  61
  62         err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
  63 #ifdef CONFIG_IP_ROUTE_CLASSID
  64         if (arg.rule)
  65                 res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
  66         else
  67                 res->tclassid = 0;
  68 #endif
  69
  70         if (err == -ESRCH)
  71                 err = -ENETUNREACH;
  72
  73         return err;
  74 }
  75 EXPORT_SYMBOL_GPL(__fib_lookup);
  76
  77 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  78                             int flags, struct fib_lookup_arg *arg)
  79 {
  80         int err = -EAGAIN;
  81         struct fib_table *tbl;
  82         u32 tb_id;
  83
  84         switch (rule->action) {
  85         case FR_ACT_TO_TBL:
  86                 break;
  87
  88         case FR_ACT_UNREACHABLE:
  89                 return -ENETUNREACH;
  90
  91         case FR_ACT_PROHIBIT:
  92                 return -EACCES;
  93
  94         case FR_ACT_BLACKHOLE:
  95         default:
  96                 return -EINVAL;
  97         }
  98
  99         rcu_read_lock();
 100
 101         tb_id = fib_rule_get_table(rule, arg);
 102         tbl = fib_get_table(rule->fr_net, tb_id);
 103         if (tbl)
 104                 err = fib_table_lookup(tbl, &flp->u.ip4,
 105                                        (struct fib_result *)arg->result,
 106                                        arg->flags);
 107
 108         rcu_read_unlock();
 109         return err;
 110 }
 111
 112 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 113 {
 114         struct fib_result *result = (struct fib_result *) arg->result;
 115         struct net_device *dev = NULL;
 116
 117         if (result->fi)
 118                 dev = result->fi->fib_dev;
 119
 120         /* do not accept result if the route does
 121          * not meet the required prefix length
 122          */
 123         if (result->prefixlen <= rule->suppress_prefixlen)
 124                 goto suppress_route;
 125
 126         /* do not accept result if the route uses a device
 127          * belonging to a forbidden interface group
 128          */
 129         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 130                 goto suppress_route;
 131
 132         return false;
 133
 134 suppress_route:
 135         if (!(arg->flags & FIB_LOOKUP_NOREF))
 136                 fib_info_put(result->fi);
 137         return true;
 138 }
 139
 140 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 141 {
 142         struct fib4_rule *r = (struct fib4_rule *) rule;
 143         struct flowi4 *fl4 = &fl->u.ip4;
 144         __be32 daddr = fl4->daddr;
 145         __be32 saddr = fl4->saddr;
 146
 147         if (((saddr ^ r->src) & r->srcmask) ||
 148             ((daddr ^ r->dst) & r->dstmask))
 149                 return 0;
 150
 151         if (r->tos && (r->tos != fl4->flowi4_tos))
 152                 return 0;
 153
 154         return 1;
 155 }
 156
 157 static struct fib_table *fib_empty_table(struct net *net)
 158 {
 159         u32 id;
 160
 161         for (id = 1; id <= RT_TABLE_MAX; id++)
 162                 if (!fib_get_table(net, id))
 163                         return fib_new_table(net, id);
 164         return NULL;
 165 }
 166
 167 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 168         FRA_GENERIC_POLICY,
 169         [FRA_FLOW]      = { .type = NLA_U32 },
 170 };
 171
 172 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 173                                struct fib_rule_hdr *frh,
 174                                struct nlattr **tb)
 175 {
 176         struct net *net = sock_net(skb->sk);
 177         int err = -EINVAL;
 178         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 179
 180         if (frh->tos & ~IPTOS_TOS_MASK)
 181                 goto errout;
 182
 183         /* split local/main if they are not already split */
 184         err = fib_unmerge(net);
 185         if (err)
 186                 goto errout;
 187
 188         if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {
 189                 if (rule->action == FR_ACT_TO_TBL) {
 190                         struct fib_table *table;
 191
 192                         table = fib_empty_table(net);
 193                         if (!table) {
 194                                 err = -ENOBUFS;
 195                                 goto errout;
 196                         }
 197
 198                         rule->table = table->tb_id;
 199                 }
 200         }
 201
 202         if (frh->src_len)
 203                 rule4->src = nla_get_in_addr(tb[FRA_SRC]);
 204
 205         if (frh->dst_len)
 206                 rule4->dst = nla_get_in_addr(tb[FRA_DST]);
 207
 208 #ifdef CONFIG_IP_ROUTE_CLASSID
 209         if (tb[FRA_FLOW]) {
 210                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 211                 if (rule4->tclassid)
 212                         net->ipv4.fib_num_tclassid_users++;
 213         }
 214 #endif
 215
 216         rule4->src_len = frh->src_len;
 217         rule4->srcmask = inet_make_mask(rule4->src_len);
 218         rule4->dst_len = frh->dst_len;
 219         rule4->dstmask = inet_make_mask(rule4->dst_len);
 220         rule4->tos = frh->tos;
 221
 222         net->ipv4.fib_has_custom_rules = true;
 223         fib_flush_external(rule->fr_net);
 224
 225         err = 0;
 226 errout:
 227         return err;
 228 }
 229
 230 static int fib4_rule_delete(struct fib_rule *rule)
 231 {
 232         struct net *net = rule->fr_net;
 233         int err;
 234
 235         /* split local/main if they are not already split */
 236         err = fib_unmerge(net);
 237         if (err)
 238                 goto errout;
 239
 240 #ifdef CONFIG_IP_ROUTE_CLASSID
 241         if (((struct fib4_rule *)rule)->tclassid)
 242                 net->ipv4.fib_num_tclassid_users--;
 243 #endif
 244         net->ipv4.fib_has_custom_rules = true;
 245         fib_flush_external(rule->fr_net);
 246 errout:
 247         return err;
 248 }
 249
 250 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 251                              struct nlattr **tb)
 252 {
 253         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 254
 255         if (frh->src_len && (rule4->src_len != frh->src_len))
 256                 return 0;
 257
 258         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 259                 return 0;
 260
 261         if (frh->tos && (rule4->tos != frh->tos))
 262                 return 0;
 263
 264 #ifdef CONFIG_IP_ROUTE_CLASSID
 265         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 266                 return 0;
 267 #endif
 268
 269         if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
 270                 return 0;
 271
 272         if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
 273                 return 0;
 274
 275         return 1;
 276 }
 277
 278 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 279                           struct fib_rule_hdr *frh)
 280 {
 281         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 282
 283         frh->dst_len = rule4->dst_len;
 284         frh->src_len = rule4->src_len;
 285         frh->tos = rule4->tos;
 286
 287         if ((rule4->dst_len &&
 288              nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
 289             (rule4->src_len &&
 290              nla_put_in_addr(skb, FRA_SRC, rule4->src)))
 291                 goto nla_put_failure;
 292 #ifdef CONFIG_IP_ROUTE_CLASSID
 293         if (rule4->tclassid &&
 294             nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
 295                 goto nla_put_failure;
 296 #endif
 297         return 0;
 298
 299 nla_put_failure:
 300         return -ENOBUFS;
 301 }
 302
 303 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 304 {
 305         return nla_total_size(4) /* dst */
 306                + nla_total_size(4) /* src */
 307                + nla_total_size(4); /* flow */
 308 }
 309
 310 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 311 {
 312         rt_cache_flush(ops->fro_net);
 313 }
 314
 315 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
 316         .family         = AF_INET,
 317         .rule_size      = sizeof(struct fib4_rule),
 318         .addr_size      = sizeof(u32),
 319         .action         = fib4_rule_action,
 320         .suppress       = fib4_rule_suppress,
 321         .match          = fib4_rule_match,
 322         .configure      = fib4_rule_configure,
 323         .delete         = fib4_rule_delete,
 324         .compare        = fib4_rule_compare,
 325         .fill           = fib4_rule_fill,
 326         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 327         .flush_cache    = fib4_rule_flush_cache,
 328         .nlgroup        = RTNLGRP_IPV4_RULE,
 329         .policy         = fib4_rule_policy,
 330         .owner          = THIS_MODULE,
 331 };
 332
 333 static int fib_default_rules_init(struct fib_rules_ops *ops)
 334 {
 335         int err;
 336
 337         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 338         if (err < 0)
 339                 return err;
 340         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 341         if (err < 0)
 342                 return err;
 343         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 344         if (err < 0)
 345                 return err;
 346         return 0;
 347 }
 348
 349 int __net_init fib4_rules_init(struct net *net)
 350 {
 351         int err;
 352         struct fib_rules_ops *ops;
 353
 354         ops = fib_rules_register(&fib4_rules_ops_template, net);
 355         if (IS_ERR(ops))
 356                 return PTR_ERR(ops);
 357
 358         err = fib_default_rules_init(ops);
 359         if (err < 0)
 360                 goto fail;
 361         net->ipv4.rules_ops = ops;
 362         net->ipv4.fib_has_custom_rules = false;
 363         return 0;
 364
 365 fail:
 366         /* also cleans all rules already added */
 367         fib_rules_unregister(ops);
 368         return err;
 369 }
 370
 371 void __net_exit fib4_rules_exit(struct net *net)
 372 {
 373         fib_rules_unregister(net->ipv4.rules_ops);
 374 }