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