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 <net/ip.h>
  30 #include <net/route.h>
  31 #include <net/tcp.h>
  32 #include <net/ip_fib.h>
  33 #include <net/fib_rules.h>
  34
  35 struct fib4_rule
  36 {
  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_NET_CLS_ROUTE
  46         u32                     tclassid;
  47 #endif
  48 };
  49
  50 #ifdef CONFIG_NET_CLS_ROUTE
  51 u32 fib_rules_tclass(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 flowi *flp, struct fib_result *res)
  58 {
  59         struct fib_lookup_arg arg = {
  60                 .result = res,
  61         };
  62         int err;
  63
  64         err = fib_rules_lookup(init_net.ipv4.rules_ops, flp, 0, &arg);
  65         res->r = arg.rule;
  66
  67         return err;
  68 }
  69
  70 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  71                             int flags, struct fib_lookup_arg *arg)
  72 {
  73         int err = -EAGAIN;
  74         struct fib_table *tbl;
  75
  76         switch (rule->action) {
  77         case FR_ACT_TO_TBL:
  78                 break;
  79
  80         case FR_ACT_UNREACHABLE:
  81                 err = -ENETUNREACH;
  82                 goto errout;
  83
  84         case FR_ACT_PROHIBIT:
  85                 err = -EACCES;
  86                 goto errout;
  87
  88         case FR_ACT_BLACKHOLE:
  89         default:
  90                 err = -EINVAL;
  91                 goto errout;
  92         }
  93
  94         if ((tbl = fib_get_table(&init_net, rule->table)) == NULL)
  95                 goto errout;
  96
  97         err = tbl->tb_lookup(tbl, flp, (struct fib_result *) arg->result);
  98         if (err > 0)
  99                 err = -EAGAIN;
 100 errout:
 101         return err;
 102 }
 103
 104
 105 void fib_select_default(const struct flowi *flp, struct fib_result *res)
 106 {
 107         if (res->r && res->r->action == FR_ACT_TO_TBL &&
 108             FIB_RES_GW(*res) && FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK) {
 109                 struct fib_table *tb;
 110                 if ((tb = fib_get_table(&init_net, res->r->table)) != NULL)
 111                         tb->tb_select_default(tb, flp, res);
 112         }
 113 }
 114
 115 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 116 {
 117         struct fib4_rule *r = (struct fib4_rule *) rule;
 118         __be32 daddr = fl->fl4_dst;
 119         __be32 saddr = fl->fl4_src;
 120
 121         if (((saddr ^ r->src) & r->srcmask) ||
 122             ((daddr ^ r->dst) & r->dstmask))
 123                 return 0;
 124
 125         if (r->tos && (r->tos != fl->fl4_tos))
 126                 return 0;
 127
 128         return 1;
 129 }
 130
 131 static struct fib_table *fib_empty_table(struct net *net)
 132 {
 133         u32 id;
 134
 135         for (id = 1; id <= RT_TABLE_MAX; id++)
 136                 if (fib_get_table(net, id) == NULL)
 137                         return fib_new_table(net, id);
 138         return NULL;
 139 }
 140
 141 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 142         FRA_GENERIC_POLICY,
 143         [FRA_FLOW]      = { .type = NLA_U32 },
 144 };
 145
 146 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 147                                struct nlmsghdr *nlh, struct fib_rule_hdr *frh,
 148                                struct nlattr **tb)
 149 {
 150         struct net *net = skb->sk->sk_net;
 151         int err = -EINVAL;
 152         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 153
 154         if (frh->tos & ~IPTOS_TOS_MASK)
 155                 goto errout;
 156
 157         if (rule->table == RT_TABLE_UNSPEC) {
 158                 if (rule->action == FR_ACT_TO_TBL) {
 159                         struct fib_table *table;
 160
 161                         table = fib_empty_table(net);
 162                         if (table == NULL) {
 163                                 err = -ENOBUFS;
 164                                 goto errout;
 165                         }
 166
 167                         rule->table = table->tb_id;
 168                 }
 169         }
 170
 171         if (frh->src_len)
 172                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 173
 174         if (frh->dst_len)
 175                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 176
 177 #ifdef CONFIG_NET_CLS_ROUTE
 178         if (tb[FRA_FLOW])
 179                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 180 #endif
 181
 182         rule4->src_len = frh->src_len;
 183         rule4->srcmask = inet_make_mask(rule4->src_len);
 184         rule4->dst_len = frh->dst_len;
 185         rule4->dstmask = inet_make_mask(rule4->dst_len);
 186         rule4->tos = frh->tos;
 187
 188         err = 0;
 189 errout:
 190         return err;
 191 }
 192
 193 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 194                              struct nlattr **tb)
 195 {
 196         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 197
 198         if (frh->src_len && (rule4->src_len != frh->src_len))
 199                 return 0;
 200
 201         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 202                 return 0;
 203
 204         if (frh->tos && (rule4->tos != frh->tos))
 205                 return 0;
 206
 207 #ifdef CONFIG_NET_CLS_ROUTE
 208         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 209                 return 0;
 210 #endif
 211
 212         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 213                 return 0;
 214
 215         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 216                 return 0;
 217
 218         return 1;
 219 }
 220
 221 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 222                           struct nlmsghdr *nlh, struct fib_rule_hdr *frh)
 223 {
 224         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 225
 226         frh->family = AF_INET;
 227         frh->dst_len = rule4->dst_len;
 228         frh->src_len = rule4->src_len;
 229         frh->tos = rule4->tos;
 230
 231         if (rule4->dst_len)
 232                 NLA_PUT_BE32(skb, FRA_DST, rule4->dst);
 233
 234         if (rule4->src_len)
 235                 NLA_PUT_BE32(skb, FRA_SRC, rule4->src);
 236
 237 #ifdef CONFIG_NET_CLS_ROUTE
 238         if (rule4->tclassid)
 239                 NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
 240 #endif
 241         return 0;
 242
 243 nla_put_failure:
 244         return -ENOBUFS;
 245 }
 246
 247 static u32 fib4_rule_default_pref(struct fib_rules_ops *ops)
 248 {
 249         struct list_head *pos;
 250         struct fib_rule *rule;
 251
 252         if (!list_empty(&ops->rules_list)) {
 253                 pos = ops->rules_list.next;
 254                 if (pos->next != &ops->rules_list) {
 255                         rule = list_entry(pos->next, struct fib_rule, list);
 256                         if (rule->pref)
 257                                 return rule->pref - 1;
 258                 }
 259         }
 260
 261         return 0;
 262 }
 263
 264 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 265 {
 266         return nla_total_size(4) /* dst */
 267                + nla_total_size(4) /* src */
 268                + nla_total_size(4); /* flow */
 269 }
 270
 271 static void fib4_rule_flush_cache(void)
 272 {
 273         rt_cache_flush(-1);
 274 }
 275
 276 static struct fib_rules_ops fib4_rules_ops_template = {
 277         .family         = AF_INET,
 278         .rule_size      = sizeof(struct fib4_rule),
 279         .addr_size      = sizeof(u32),
 280         .action         = fib4_rule_action,
 281         .match          = fib4_rule_match,
 282         .configure      = fib4_rule_configure,
 283         .compare        = fib4_rule_compare,
 284         .fill           = fib4_rule_fill,
 285         .default_pref   = fib4_rule_default_pref,
 286         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 287         .flush_cache    = fib4_rule_flush_cache,
 288         .nlgroup        = RTNLGRP_IPV4_RULE,
 289         .policy         = fib4_rule_policy,
 290         .owner          = THIS_MODULE,
 291 };
 292
 293 static int fib_default_rules_init(struct fib_rules_ops *ops)
 294 {
 295         int err;
 296
 297         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, FIB_RULE_PERMANENT);
 298         if (err < 0)
 299                 return err;
 300         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 301         if (err < 0)
 302                 return err;
 303         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 304         if (err < 0)
 305                 return err;
 306         return 0;
 307 }
 308
 309 int __net_init fib4_rules_init(struct net *net)
 310 {
 311         int err;
 312         struct fib_rules_ops *ops;
 313
 314         ops = kmemdup(&fib4_rules_ops_template, sizeof(*ops), GFP_KERNEL);
 315         if (ops == NULL)
 316                 return -ENOMEM;
 317         INIT_LIST_HEAD(&ops->rules_list);
 318         fib_rules_register(net, ops);
 319
 320         err = fib_default_rules_init(ops);
 321         if (err < 0)
 322                 goto fail;
 323         net->ipv4.rules_ops = ops;
 324         return 0;
 325
 326 fail:
 327         /* also cleans all rules already added */
 328         fib_rules_unregister(net, ops);
 329         kfree(ops);
 330         return err;
 331 }
 332
 333 void __net_exit fib4_rules_exit(struct net *net)
 334 {
 335         fib_rules_unregister(net, net->ipv4.rules_ops);
 336         kfree(net->ipv4.rules_ops);
 337 }