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, struct fib_result *res)
  51 {
  52         struct fib_lookup_arg arg = {
  53                 .result = res,
  54                 .flags = FIB_LOOKUP_NOREF,
  55         };
  56         int err;
  57
  58         err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
  59 #ifdef CONFIG_IP_ROUTE_CLASSID
  60         if (arg.rule)
  61                 res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
  62         else
  63                 res->tclassid = 0;
  64 #endif
  65         return err;
  66 }
  67 EXPORT_SYMBOL_GPL(__fib_lookup);
  68
  69 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  70                             int flags, struct fib_lookup_arg *arg)
  71 {
  72         int err = -EAGAIN;
  73         struct fib_table *tbl;
  74
  75         switch (rule->action) {
  76         case FR_ACT_TO_TBL:
  77                 break;
  78
  79         case FR_ACT_UNREACHABLE:
  80                 err = -ENETUNREACH;
  81                 goto errout;
  82
  83         case FR_ACT_PROHIBIT:
  84                 err = -EACCES;
  85                 goto errout;
  86
  87         case FR_ACT_BLACKHOLE:
  88         default:
  89                 err = -EINVAL;
  90                 goto errout;
  91         }
  92
  93         tbl = fib_get_table(rule->fr_net, rule->table);
  94         if (!tbl)
  95                 goto errout;
  96
  97         err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
  98         if (err > 0)
  99                 err = -EAGAIN;
 100 errout:
 101         return err;
 102 }
 103
 104
 105 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 106 {
 107         struct fib4_rule *r = (struct fib4_rule *) rule;
 108         struct flowi4 *fl4 = &fl->u.ip4;
 109         __be32 daddr = fl4->daddr;
 110         __be32 saddr = fl4->saddr;
 111
 112         if (((saddr ^ r->src) & r->srcmask) ||
 113             ((daddr ^ r->dst) & r->dstmask))
 114                 return 0;
 115
 116         if (r->tos && (r->tos != fl4->flowi4_tos))
 117                 return 0;
 118
 119         return 1;
 120 }
 121
 122 static struct fib_table *fib_empty_table(struct net *net)
 123 {
 124         u32 id;
 125
 126         for (id = 1; id <= RT_TABLE_MAX; id++)
 127                 if (fib_get_table(net, id) == NULL)
 128                         return fib_new_table(net, id);
 129         return NULL;
 130 }
 131
 132 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 133         FRA_GENERIC_POLICY,
 134         [FRA_FLOW]      = { .type = NLA_U32 },
 135 };
 136
 137 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 138                                struct fib_rule_hdr *frh,
 139                                struct nlattr **tb)
 140 {
 141         struct net *net = sock_net(skb->sk);
 142         int err = -EINVAL;
 143         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 144
 145         if (frh->tos & ~IPTOS_TOS_MASK)
 146                 goto errout;
 147
 148         if (rule->table == RT_TABLE_UNSPEC) {
 149                 if (rule->action == FR_ACT_TO_TBL) {
 150                         struct fib_table *table;
 151
 152                         table = fib_empty_table(net);
 153                         if (table == NULL) {
 154                                 err = -ENOBUFS;
 155                                 goto errout;
 156                         }
 157
 158                         rule->table = table->tb_id;
 159                 }
 160         }
 161
 162         if (frh->src_len)
 163                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 164
 165         if (frh->dst_len)
 166                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 167
 168 #ifdef CONFIG_IP_ROUTE_CLASSID
 169         if (tb[FRA_FLOW]) {
 170                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 171                 if (rule4->tclassid)
 172                         net->ipv4.fib_num_tclassid_users++;
 173         }
 174 #endif
 175
 176         rule4->src_len = frh->src_len;
 177         rule4->srcmask = inet_make_mask(rule4->src_len);
 178         rule4->dst_len = frh->dst_len;
 179         rule4->dstmask = inet_make_mask(rule4->dst_len);
 180         rule4->tos = frh->tos;
 181
 182         net->ipv4.fib_has_custom_rules = true;
 183         err = 0;
 184 errout:
 185         return err;
 186 }
 187
 188 static void fib4_rule_delete(struct fib_rule *rule)
 189 {
 190         struct net *net = rule->fr_net;
 191 #ifdef CONFIG_IP_ROUTE_CLASSID
 192         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 193
 194         if (rule4->tclassid)
 195                 net->ipv4.fib_num_tclassid_users--;
 196 #endif
 197         net->ipv4.fib_has_custom_rules = true;
 198 }
 199
 200 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 201                              struct nlattr **tb)
 202 {
 203         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 204
 205         if (frh->src_len && (rule4->src_len != frh->src_len))
 206                 return 0;
 207
 208         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 209                 return 0;
 210
 211         if (frh->tos && (rule4->tos != frh->tos))
 212                 return 0;
 213
 214 #ifdef CONFIG_IP_ROUTE_CLASSID
 215         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 216                 return 0;
 217 #endif
 218
 219         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 220                 return 0;
 221
 222         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 223                 return 0;
 224
 225         return 1;
 226 }
 227
 228 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 229                           struct fib_rule_hdr *frh)
 230 {
 231         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 232
 233         frh->dst_len = rule4->dst_len;
 234         frh->src_len = rule4->src_len;
 235         frh->tos = rule4->tos;
 236
 237         if ((rule4->dst_len &&
 238              nla_put_be32(skb, FRA_DST, rule4->dst)) ||
 239             (rule4->src_len &&
 240              nla_put_be32(skb, FRA_SRC, rule4->src)))
 241                 goto nla_put_failure;
 242 #ifdef CONFIG_IP_ROUTE_CLASSID
 243         if (rule4->tclassid &&
 244             nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
 245                 goto nla_put_failure;
 246 #endif
 247         return 0;
 248
 249 nla_put_failure:
 250         return -ENOBUFS;
 251 }
 252
 253 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 254 {
 255         return nla_total_size(4) /* dst */
 256                + nla_total_size(4) /* src */
 257                + nla_total_size(4); /* flow */
 258 }
 259
 260 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 261 {
 262         rt_cache_flush(ops->fro_net);
 263 }
 264
 265 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
 266         .family         = AF_INET,
 267         .rule_size      = sizeof(struct fib4_rule),
 268         .addr_size      = sizeof(u32),
 269         .action         = fib4_rule_action,
 270         .match          = fib4_rule_match,
 271         .configure      = fib4_rule_configure,
 272         .delete         = fib4_rule_delete,
 273         .compare        = fib4_rule_compare,
 274         .fill           = fib4_rule_fill,
 275         .default_pref   = fib_default_rule_pref,
 276         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 277         .flush_cache    = fib4_rule_flush_cache,
 278         .nlgroup        = RTNLGRP_IPV4_RULE,
 279         .policy         = fib4_rule_policy,
 280         .owner          = THIS_MODULE,
 281 };
 282
 283 static int fib_default_rules_init(struct fib_rules_ops *ops)
 284 {
 285         int err;
 286
 287         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 288         if (err < 0)
 289                 return err;
 290         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 291         if (err < 0)
 292                 return err;
 293         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 294         if (err < 0)
 295                 return err;
 296         return 0;
 297 }
 298
 299 int __net_init fib4_rules_init(struct net *net)
 300 {
 301         int err;
 302         struct fib_rules_ops *ops;
 303
 304         ops = fib_rules_register(&fib4_rules_ops_template, net);
 305         if (IS_ERR(ops))
 306                 return PTR_ERR(ops);
 307
 308         err = fib_default_rules_init(ops);
 309         if (err < 0)
 310                 goto fail;
 311         net->ipv4.rules_ops = ops;
 312         net->ipv4.fib_has_custom_rules = false;
 313         return 0;
 314
 315 fail:
 316         /* also cleans all rules already added */
 317         fib_rules_unregister(ops);
 318         return err;
 319 }
 320
 321 void __net_exit fib4_rules_exit(struct net *net)
 322 {
 323         fib_rules_unregister(net->ipv4.rules_ops);
 324 }