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