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 #ifdef CONFIG_IP_ROUTE_CLASSID
  51 u32 fib_rules_tclass(const struct fib_result *res)
  52 {
  53         return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
  54 }
  55 #endif
  56
  57 int __fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
  58 {
  59         struct fib_lookup_arg arg = {
  60                 .result = res,
  61                 .flags = FIB_LOOKUP_NOREF,
  62         };
  63         int err;
  64
  65         err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
  66         res->r = arg.rule;
  67
  68         return err;
  69 }
  70 EXPORT_SYMBOL_GPL(__fib_lookup);
  71
  72 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  73                             int flags, struct fib_lookup_arg *arg)
  74 {
  75         int err = -EAGAIN;
  76         struct fib_table *tbl;
  77
  78         switch (rule->action) {
  79         case FR_ACT_TO_TBL:
  80                 break;
  81
  82         case FR_ACT_UNREACHABLE:
  83                 err = -ENETUNREACH;
  84                 goto errout;
  85
  86         case FR_ACT_PROHIBIT:
  87                 err = -EACCES;
  88                 goto errout;
  89
  90         case FR_ACT_BLACKHOLE:
  91         default:
  92                 err = -EINVAL;
  93                 goto errout;
  94         }
  95
  96         tbl = fib_get_table(rule->fr_net, rule->table);
  97         if (!tbl)
  98                 goto errout;
  99
 100         err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
 101         if (err > 0)
 102                 err = -EAGAIN;
 103 errout:
 104         return err;
 105 }
 106
 107
 108 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 109 {
 110         struct fib4_rule *r = (struct fib4_rule *) rule;
 111         struct flowi4 *fl4 = &fl->u.ip4;
 112         __be32 daddr = fl4->daddr;
 113         __be32 saddr = fl4->saddr;
 114
 115         if (((saddr ^ r->src) & r->srcmask) ||
 116             ((daddr ^ r->dst) & r->dstmask))
 117                 return 0;
 118
 119         if (r->tos && (r->tos != fl4->flowi4_tos))
 120                 return 0;
 121
 122         return 1;
 123 }
 124
 125 static struct fib_table *fib_empty_table(struct net *net)
 126 {
 127         u32 id;
 128
 129         for (id = 1; id <= RT_TABLE_MAX; id++)
 130                 if (fib_get_table(net, id) == NULL)
 131                         return fib_new_table(net, id);
 132         return NULL;
 133 }
 134
 135 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 136         FRA_GENERIC_POLICY,
 137         [FRA_FLOW]      = { .type = NLA_U32 },
 138 };
 139
 140 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 141                                struct fib_rule_hdr *frh,
 142                                struct nlattr **tb)
 143 {
 144         struct net *net = sock_net(skb->sk);
 145         int err = -EINVAL;
 146         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 147
 148         if (frh->tos & ~IPTOS_TOS_MASK)
 149                 goto errout;
 150
 151         if (rule->table == RT_TABLE_UNSPEC) {
 152                 if (rule->action == FR_ACT_TO_TBL) {
 153                         struct fib_table *table;
 154
 155                         table = fib_empty_table(net);
 156                         if (table == NULL) {
 157                                 err = -ENOBUFS;
 158                                 goto errout;
 159                         }
 160
 161                         rule->table = table->tb_id;
 162                 }
 163         }
 164
 165         if (frh->src_len)
 166                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 167
 168         if (frh->dst_len)
 169                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 170
 171 #ifdef CONFIG_IP_ROUTE_CLASSID
 172         if (tb[FRA_FLOW]) {
 173                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 174                 if (rule4->tclassid)
 175                         net->ipv4.fib_num_tclassid_users++;
 176         }
 177 #endif
 178
 179         rule4->src_len = frh->src_len;
 180         rule4->srcmask = inet_make_mask(rule4->src_len);
 181         rule4->dst_len = frh->dst_len;
 182         rule4->dstmask = inet_make_mask(rule4->dst_len);
 183         rule4->tos = frh->tos;
 184
 185         net->ipv4.fib_has_custom_rules = true;
 186         err = 0;
 187 errout:
 188         return err;
 189 }
 190
 191 static void fib4_rule_delete(struct fib_rule *rule)
 192 {
 193         struct net *net = rule->fr_net;
 194 #ifdef CONFIG_IP_ROUTE_CLASSID
 195         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 196
 197         if (rule4->tclassid)
 198                 net->ipv4.fib_num_tclassid_users--;
 199 #endif
 200         net->ipv4.fib_has_custom_rules = true;
 201 }
 202
 203 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 204                              struct nlattr **tb)
 205 {
 206         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 207
 208         if (frh->src_len && (rule4->src_len != frh->src_len))
 209                 return 0;
 210
 211         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 212                 return 0;
 213
 214         if (frh->tos && (rule4->tos != frh->tos))
 215                 return 0;
 216
 217 #ifdef CONFIG_IP_ROUTE_CLASSID
 218         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 219                 return 0;
 220 #endif
 221
 222         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 223                 return 0;
 224
 225         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 226                 return 0;
 227
 228         return 1;
 229 }
 230
 231 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 232                           struct fib_rule_hdr *frh)
 233 {
 234         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 235
 236         frh->dst_len = rule4->dst_len;
 237         frh->src_len = rule4->src_len;
 238         frh->tos = rule4->tos;
 239
 240         if ((rule4->dst_len &&
 241              nla_put_be32(skb, FRA_DST, rule4->dst)) ||
 242             (rule4->src_len &&
 243              nla_put_be32(skb, FRA_SRC, rule4->src)))
 244                 goto nla_put_failure;
 245 #ifdef CONFIG_IP_ROUTE_CLASSID
 246         if (rule4->tclassid &&
 247             nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
 248                 goto nla_put_failure;
 249 #endif
 250         return 0;
 251
 252 nla_put_failure:
 253         return -ENOBUFS;
 254 }
 255
 256 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 257 {
 258         return nla_total_size(4) /* dst */
 259                + nla_total_size(4) /* src */
 260                + nla_total_size(4); /* flow */
 261 }
 262
 263 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 264 {
 265         rt_cache_flush(ops->fro_net, -1);
 266 }
 267
 268 static const struct fib_rules_ops __net_initdata fib4_rules_ops_template = {
 269         .family         = AF_INET,
 270         .rule_size      = sizeof(struct fib4_rule),
 271         .addr_size      = sizeof(u32),
 272         .action         = fib4_rule_action,
 273         .match          = fib4_rule_match,
 274         .configure      = fib4_rule_configure,
 275         .delete         = fib4_rule_delete,
 276         .compare        = fib4_rule_compare,
 277         .fill           = fib4_rule_fill,
 278         .default_pref   = fib_default_rule_pref,
 279         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 280         .flush_cache    = fib4_rule_flush_cache,
 281         .nlgroup        = RTNLGRP_IPV4_RULE,
 282         .policy         = fib4_rule_policy,
 283         .owner          = THIS_MODULE,
 284 };
 285
 286 static int fib_default_rules_init(struct fib_rules_ops *ops)
 287 {
 288         int err;
 289
 290         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 291         if (err < 0)
 292                 return err;
 293         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 294         if (err < 0)
 295                 return err;
 296         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 297         if (err < 0)
 298                 return err;
 299         return 0;
 300 }
 301
 302 int __net_init fib4_rules_init(struct net *net)
 303 {
 304         int err;
 305         struct fib_rules_ops *ops;
 306
 307         ops = fib_rules_register(&fib4_rules_ops_template, net);
 308         if (IS_ERR(ops))
 309                 return PTR_ERR(ops);
 310
 311         err = fib_default_rules_init(ops);
 312         if (err < 0)
 313                 goto fail;
 314         net->ipv4.rules_ops = ops;
 315         net->ipv4.fib_has_custom_rules = false;
 316         return 0;
 317
 318 fail:
 319         /* also cleans all rules already added */
 320         fib_rules_unregister(ops);
 321         return err;
 322 }
 323
 324 void __net_exit fib4_rules_exit(struct net *net)
 325 {
 326         fib_rules_unregister(net->ipv4.rules_ops);
 327 }