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
  66         if (err == -ESRCH)
  67                 err = -ENETUNREACH;
  68
  69         return err;
  70 }
  71 EXPORT_SYMBOL_GPL(__fib_lookup);
  72
  73 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  74                             int flags, struct fib_lookup_arg *arg)
  75 {
  76         int err = -EAGAIN;
  77         struct fib_table *tbl;
  78
  79         switch (rule->action) {
  80         case FR_ACT_TO_TBL:
  81                 break;
  82
  83         case FR_ACT_UNREACHABLE:
  84                 return -ENETUNREACH;
  85
  86         case FR_ACT_PROHIBIT:
  87                 return -EACCES;
  88
  89         case FR_ACT_BLACKHOLE:
  90         default:
  91                 return -EINVAL;
  92         }
  93
  94         rcu_read_lock();
  95
  96         tbl = fib_get_table(rule->fr_net, rule->table);
  97         if (tbl)
  98                 err = fib_table_lookup(tbl, &flp->u.ip4,
  99                                        (struct fib_result *)arg->result,
 100                                        arg->flags);
 101
 102         rcu_read_unlock();
 103         return err;
 104 }
 105
 106 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 107 {
 108         struct fib_result *result = (struct fib_result *) arg->result;
 109         struct net_device *dev = NULL;
 110
 111         if (result->fi)
 112                 dev = result->fi->fib_dev;
 113
 114         /* do not accept result if the route does
 115          * not meet the required prefix length
 116          */
 117         if (result->prefixlen <= rule->suppress_prefixlen)
 118                 goto suppress_route;
 119
 120         /* do not accept result if the route uses a device
 121          * belonging to a forbidden interface group
 122          */
 123         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 124                 goto suppress_route;
 125
 126         return false;
 127
 128 suppress_route:
 129         if (!(arg->flags & FIB_LOOKUP_NOREF))
 130                 fib_info_put(result->fi);
 131         return true;
 132 }
 133
 134 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 135 {
 136         struct fib4_rule *r = (struct fib4_rule *) rule;
 137         struct flowi4 *fl4 = &fl->u.ip4;
 138         __be32 daddr = fl4->daddr;
 139         __be32 saddr = fl4->saddr;
 140
 141         if (((saddr ^ r->src) & r->srcmask) ||
 142             ((daddr ^ r->dst) & r->dstmask))
 143                 return 0;
 144
 145         if (r->tos && (r->tos != fl4->flowi4_tos))
 146                 return 0;
 147
 148         return 1;
 149 }
 150
 151 static struct fib_table *fib_empty_table(struct net *net)
 152 {
 153         u32 id;
 154
 155         for (id = 1; id <= RT_TABLE_MAX; id++)
 156                 if (fib_get_table(net, id) == NULL)
 157                         return fib_new_table(net, id);
 158         return NULL;
 159 }
 160
 161 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 162         FRA_GENERIC_POLICY,
 163         [FRA_FLOW]      = { .type = NLA_U32 },
 164 };
 165
 166 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 167                                struct fib_rule_hdr *frh,
 168                                struct nlattr **tb)
 169 {
 170         struct net *net = sock_net(skb->sk);
 171         int err = -EINVAL;
 172         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 173
 174         if (frh->tos & ~IPTOS_TOS_MASK)
 175                 goto errout;
 176
 177         if (rule->table == RT_TABLE_UNSPEC) {
 178                 if (rule->action == FR_ACT_TO_TBL) {
 179                         struct fib_table *table;
 180
 181                         table = fib_empty_table(net);
 182                         if (table == NULL) {
 183                                 err = -ENOBUFS;
 184                                 goto errout;
 185                         }
 186
 187                         rule->table = table->tb_id;
 188                 }
 189         }
 190
 191         if (frh->src_len)
 192                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 193
 194         if (frh->dst_len)
 195                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 196
 197 #ifdef CONFIG_IP_ROUTE_CLASSID
 198         if (tb[FRA_FLOW]) {
 199                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 200                 if (rule4->tclassid)
 201                         net->ipv4.fib_num_tclassid_users++;
 202         }
 203 #endif
 204
 205         rule4->src_len = frh->src_len;
 206         rule4->srcmask = inet_make_mask(rule4->src_len);
 207         rule4->dst_len = frh->dst_len;
 208         rule4->dstmask = inet_make_mask(rule4->dst_len);
 209         rule4->tos = frh->tos;
 210
 211         net->ipv4.fib_has_custom_rules = true;
 212         err = 0;
 213 errout:
 214         return err;
 215 }
 216
 217 static void fib4_rule_delete(struct fib_rule *rule)
 218 {
 219         struct net *net = rule->fr_net;
 220 #ifdef CONFIG_IP_ROUTE_CLASSID
 221         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 222
 223         if (rule4->tclassid)
 224                 net->ipv4.fib_num_tclassid_users--;
 225 #endif
 226         net->ipv4.fib_has_custom_rules = true;
 227 }
 228
 229 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 230                              struct nlattr **tb)
 231 {
 232         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 233
 234         if (frh->src_len && (rule4->src_len != frh->src_len))
 235                 return 0;
 236
 237         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 238                 return 0;
 239
 240         if (frh->tos && (rule4->tos != frh->tos))
 241                 return 0;
 242
 243 #ifdef CONFIG_IP_ROUTE_CLASSID
 244         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 245                 return 0;
 246 #endif
 247
 248         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 249                 return 0;
 250
 251         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 252                 return 0;
 253
 254         return 1;
 255 }
 256
 257 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 258                           struct fib_rule_hdr *frh)
 259 {
 260         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 261
 262         frh->dst_len = rule4->dst_len;
 263         frh->src_len = rule4->src_len;
 264         frh->tos = rule4->tos;
 265
 266         if ((rule4->dst_len &&
 267              nla_put_be32(skb, FRA_DST, rule4->dst)) ||
 268             (rule4->src_len &&
 269              nla_put_be32(skb, FRA_SRC, rule4->src)))
 270                 goto nla_put_failure;
 271 #ifdef CONFIG_IP_ROUTE_CLASSID
 272         if (rule4->tclassid &&
 273             nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
 274                 goto nla_put_failure;
 275 #endif
 276         return 0;
 277
 278 nla_put_failure:
 279         return -ENOBUFS;
 280 }
 281
 282 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 283 {
 284         return nla_total_size(4) /* dst */
 285                + nla_total_size(4) /* src */
 286                + nla_total_size(4); /* flow */
 287 }
 288
 289 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 290 {
 291         rt_cache_flush(ops->fro_net);
 292 }
 293
 294 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
 295         .family         = AF_INET,
 296         .rule_size      = sizeof(struct fib4_rule),
 297         .addr_size      = sizeof(u32),
 298         .action         = fib4_rule_action,
 299         .suppress       = fib4_rule_suppress,
 300         .match          = fib4_rule_match,
 301         .configure      = fib4_rule_configure,
 302         .delete         = fib4_rule_delete,
 303         .compare        = fib4_rule_compare,
 304         .fill           = fib4_rule_fill,
 305         .default_pref   = fib_default_rule_pref,
 306         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 307         .flush_cache    = fib4_rule_flush_cache,
 308         .nlgroup        = RTNLGRP_IPV4_RULE,
 309         .policy         = fib4_rule_policy,
 310         .owner          = THIS_MODULE,
 311 };
 312
 313 static int fib_default_rules_init(struct fib_rules_ops *ops)
 314 {
 315         int err;
 316
 317         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 318         if (err < 0)
 319                 return err;
 320         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 321         if (err < 0)
 322                 return err;
 323         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 324         if (err < 0)
 325                 return err;
 326         return 0;
 327 }
 328
 329 int __net_init fib4_rules_init(struct net *net)
 330 {
 331         int err;
 332         struct fib_rules_ops *ops;
 333
 334         ops = fib_rules_register(&fib4_rules_ops_template, net);
 335         if (IS_ERR(ops))
 336                 return PTR_ERR(ops);
 337
 338         err = fib_default_rules_init(ops);
 339         if (err < 0)
 340                 goto fail;
 341         net->ipv4.rules_ops = ops;
 342         net->ipv4.fib_has_custom_rules = false;
 343         return 0;
 344
 345 fail:
 346         /* also cleans all rules already added */
 347         fib_rules_unregister(ops);
 348         return err;
 349 }
 350
 351 void __net_exit fib4_rules_exit(struct net *net)
 352 {
 353         fib_rules_unregister(net->ipv4.rules_ops);
 354 }