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         struct fib_rule         common;
  37         u8                      dst_len;
  38         u8                      src_len;
  39         u8                      tos;
  40         __be32                  src;
  41         __be32                  srcmask;
  42         __be32                  dst;
  43         __be32                  dstmask;
  44 #ifdef CONFIG_IP_ROUTE_CLASSID
  45         u32                     tclassid;
  46 #endif
  47 };
  48
  49 #ifdef CONFIG_IP_ROUTE_CLASSID
  50 u32 fib_rules_tclass(const struct fib_result *res)
  51 {
  52         return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
  53 }
  54 #endif
  55
  56 int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
  57 {
  58         struct fib_lookup_arg arg = {
  59                 .result = res,
  60                 .flags = FIB_LOOKUP_NOREF,
  61         };
  62         int err;
  63
  64         err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(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         tbl = fib_get_table(rule->fr_net, rule->table);
  95         if (!tbl)
  96                 goto errout;
  97
  98         err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
  99         if (err > 0)
 100                 err = -EAGAIN;
 101 errout:
 102         return err;
 103 }
 104
 105
 106 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 107 {
 108         struct fib4_rule *r = (struct fib4_rule *) rule;
 109         __be32 daddr = fl->fl4_dst;
 110         __be32 saddr = fl->fl4_src;
 111
 112         if (((saddr ^ r->src) & r->srcmask) ||
 113             ((daddr ^ r->dst) & r->dstmask))
 114                 return 0;
 115
 116         if (r->tos && (r->tos != fl->fl4_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 #endif
 172
 173         rule4->src_len = frh->src_len;
 174         rule4->srcmask = inet_make_mask(rule4->src_len);
 175         rule4->dst_len = frh->dst_len;
 176         rule4->dstmask = inet_make_mask(rule4->dst_len);
 177         rule4->tos = frh->tos;
 178
 179         err = 0;
 180 errout:
 181         return err;
 182 }
 183
 184 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 185                              struct nlattr **tb)
 186 {
 187         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 188
 189         if (frh->src_len && (rule4->src_len != frh->src_len))
 190                 return 0;
 191
 192         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 193                 return 0;
 194
 195         if (frh->tos && (rule4->tos != frh->tos))
 196                 return 0;
 197
 198 #ifdef CONFIG_IP_ROUTE_CLASSID
 199         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 200                 return 0;
 201 #endif
 202
 203         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 204                 return 0;
 205
 206         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 207                 return 0;
 208
 209         return 1;
 210 }
 211
 212 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 213                           struct fib_rule_hdr *frh)
 214 {
 215         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 216
 217         frh->dst_len = rule4->dst_len;
 218         frh->src_len = rule4->src_len;
 219         frh->tos = rule4->tos;
 220
 221         if (rule4->dst_len)
 222                 NLA_PUT_BE32(skb, FRA_DST, rule4->dst);
 223
 224         if (rule4->src_len)
 225                 NLA_PUT_BE32(skb, FRA_SRC, rule4->src);
 226
 227 #ifdef CONFIG_IP_ROUTE_CLASSID
 228         if (rule4->tclassid)
 229                 NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
 230 #endif
 231         return 0;
 232
 233 nla_put_failure:
 234         return -ENOBUFS;
 235 }
 236
 237 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 238 {
 239         return nla_total_size(4) /* dst */
 240                + nla_total_size(4) /* src */
 241                + nla_total_size(4); /* flow */
 242 }
 243
 244 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 245 {
 246         rt_cache_flush(ops->fro_net, -1);
 247 }
 248
 249 static const struct fib_rules_ops __net_initdata fib4_rules_ops_template = {
 250         .family         = AF_INET,
 251         .rule_size      = sizeof(struct fib4_rule),
 252         .addr_size      = sizeof(u32),
 253         .action         = fib4_rule_action,
 254         .match          = fib4_rule_match,
 255         .configure      = fib4_rule_configure,
 256         .compare        = fib4_rule_compare,
 257         .fill           = fib4_rule_fill,
 258         .default_pref   = fib_default_rule_pref,
 259         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 260         .flush_cache    = fib4_rule_flush_cache,
 261         .nlgroup        = RTNLGRP_IPV4_RULE,
 262         .policy         = fib4_rule_policy,
 263         .owner          = THIS_MODULE,
 264 };
 265
 266 static int fib_default_rules_init(struct fib_rules_ops *ops)
 267 {
 268         int err;
 269
 270         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 271         if (err < 0)
 272                 return err;
 273         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 274         if (err < 0)
 275                 return err;
 276         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 277         if (err < 0)
 278                 return err;
 279         return 0;
 280 }
 281
 282 int __net_init fib4_rules_init(struct net *net)
 283 {
 284         int err;
 285         struct fib_rules_ops *ops;
 286
 287         ops = fib_rules_register(&fib4_rules_ops_template, net);
 288         if (IS_ERR(ops))
 289                 return PTR_ERR(ops);
 290
 291         err = fib_default_rules_init(ops);
 292         if (err < 0)
 293                 goto fail;
 294         net->ipv4.rules_ops = ops;
 295         return 0;
 296
 297 fail:
 298         /* also cleans all rules already added */
 299         fib_rules_unregister(ops);
 300         return err;
 301 }
 302
 303 void __net_exit fib4_rules_exit(struct net *net)
 304 {
 305         fib_rules_unregister(net->ipv4.rules_ops);
 306 }