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