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 net *net, 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(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(rule->fr_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 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 106 {
 107         struct fib4_rule *r = (struct fib4_rule *) rule;
 108         __be32 daddr = fl->fl4_dst;
 109         __be32 saddr = fl->fl4_src;
 110
 111         if (((saddr ^ r->src) & r->srcmask) ||
 112             ((daddr ^ r->dst) & r->dstmask))
 113                 return 0;
 114
 115         if (r->tos && (r->tos != fl->fl4_tos))
 116                 return 0;
 117
 118         return 1;
 119 }
 120
 121 static struct fib_table *fib_empty_table(struct net *net)
 122 {
 123         u32 id;
 124
 125         for (id = 1; id <= RT_TABLE_MAX; id++)
 126                 if (fib_get_table(net, id) == NULL)
 127                         return fib_new_table(net, id);
 128         return NULL;
 129 }
 130
 131 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 132         FRA_GENERIC_POLICY,
 133         [FRA_FLOW]      = { .type = NLA_U32 },
 134 };
 135
 136 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 137                                struct fib_rule_hdr *frh,
 138                                struct nlattr **tb)
 139 {
 140         struct net *net = sock_net(skb->sk);
 141         int err = -EINVAL;
 142         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 143
 144         if (frh->tos & ~IPTOS_TOS_MASK)
 145                 goto errout;
 146
 147         if (rule->table == RT_TABLE_UNSPEC) {
 148                 if (rule->action == FR_ACT_TO_TBL) {
 149                         struct fib_table *table;
 150
 151                         table = fib_empty_table(net);
 152                         if (table == NULL) {
 153                                 err = -ENOBUFS;
 154                                 goto errout;
 155                         }
 156
 157                         rule->table = table->tb_id;
 158                 }
 159         }
 160
 161         if (frh->src_len)
 162                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 163
 164         if (frh->dst_len)
 165                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 166
 167 #ifdef CONFIG_NET_CLS_ROUTE
 168         if (tb[FRA_FLOW])
 169                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 170 #endif
 171
 172         rule4->src_len = frh->src_len;
 173         rule4->srcmask = inet_make_mask(rule4->src_len);
 174         rule4->dst_len = frh->dst_len;
 175         rule4->dstmask = inet_make_mask(rule4->dst_len);
 176         rule4->tos = frh->tos;
 177
 178         err = 0;
 179 errout:
 180         return err;
 181 }
 182
 183 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 184                              struct nlattr **tb)
 185 {
 186         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 187
 188         if (frh->src_len && (rule4->src_len != frh->src_len))
 189                 return 0;
 190
 191         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 192                 return 0;
 193
 194         if (frh->tos && (rule4->tos != frh->tos))
 195                 return 0;
 196
 197 #ifdef CONFIG_NET_CLS_ROUTE
 198         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 199                 return 0;
 200 #endif
 201
 202         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 203                 return 0;
 204
 205         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 206                 return 0;
 207
 208         return 1;
 209 }
 210
 211 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 212                           struct fib_rule_hdr *frh)
 213 {
 214         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 215
 216         frh->family = AF_INET;
 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_NET_CLS_ROUTE
 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 u32 fib4_rule_default_pref(struct fib_rules_ops *ops)
 238 {
 239         struct list_head *pos;
 240         struct fib_rule *rule;
 241
 242         if (!list_empty(&ops->rules_list)) {
 243                 pos = ops->rules_list.next;
 244                 if (pos->next != &ops->rules_list) {
 245                         rule = list_entry(pos->next, struct fib_rule, list);
 246                         if (rule->pref)
 247                                 return rule->pref - 1;
 248                 }
 249         }
 250
 251         return 0;
 252 }
 253
 254 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 255 {
 256         return nla_total_size(4) /* dst */
 257                + nla_total_size(4) /* src */
 258                + nla_total_size(4); /* flow */
 259 }
 260
 261 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 262 {
 263         rt_cache_flush(ops->fro_net, -1);
 264 }
 265
 266 static struct fib_rules_ops fib4_rules_ops_template = {
 267         .family         = AF_INET,
 268         .rule_size      = sizeof(struct fib4_rule),
 269         .addr_size      = sizeof(u32),
 270         .action         = fib4_rule_action,
 271         .match          = fib4_rule_match,
 272         .configure      = fib4_rule_configure,
 273         .compare        = fib4_rule_compare,
 274         .fill           = fib4_rule_fill,
 275         .default_pref   = fib4_rule_default_pref,
 276         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 277         .flush_cache    = fib4_rule_flush_cache,
 278         .nlgroup        = RTNLGRP_IPV4_RULE,
 279         .policy         = fib4_rule_policy,
 280         .owner          = THIS_MODULE,
 281 };
 282
 283 static int fib_default_rules_init(struct fib_rules_ops *ops)
 284 {
 285         int err;
 286
 287         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, FIB_RULE_PERMANENT);
 288         if (err < 0)
 289                 return err;
 290         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 291         if (err < 0)
 292                 return err;
 293         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 294         if (err < 0)
 295                 return err;
 296         return 0;
 297 }
 298
 299 int __net_init fib4_rules_init(struct net *net)
 300 {
 301         int err;
 302         struct fib_rules_ops *ops;
 303
 304         ops = kmemdup(&fib4_rules_ops_template, sizeof(*ops), GFP_KERNEL);
 305         if (ops == NULL)
 306                 return -ENOMEM;
 307         INIT_LIST_HEAD(&ops->rules_list);
 308         ops->fro_net = net;
 309
 310         fib_rules_register(ops);
 311
 312         err = fib_default_rules_init(ops);
 313         if (err < 0)
 314                 goto fail;
 315         net->ipv4.rules_ops = ops;
 316         return 0;
 317
 318 fail:
 319         /* also cleans all rules already added */
 320         fib_rules_unregister(ops);
 321         kfree(ops);
 322         return err;
 323 }
 324
 325 void __net_exit fib4_rules_exit(struct net *net)
 326 {
 327         fib_rules_unregister(net->ipv4.rules_ops);
 328         kfree(net->ipv4.rules_ops);
 329 }