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 = NULL;
 108
 109         if (result->fi)
 110                 dev = result->fi->fib_dev;
 111
 112         /* do not accept result if the route does
 113          * not meet the required prefix length
 114          */
 115         if (result->prefixlen <= rule->suppress_prefixlen)
 116                 goto suppress_route;
 117
 118         /* do not accept result if the route uses a device
 119          * belonging to a forbidden interface group
 120          */
 121         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 122                 goto suppress_route;
 123
 124         return false;
 125
 126 suppress_route:
 127         if (!(arg->flags & FIB_LOOKUP_NOREF))
 128                 fib_info_put(result->fi);
 129         return true;
 130 }
 131
 132 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 133 {
 134         struct fib4_rule *r = (struct fib4_rule *) rule;
 135         struct flowi4 *fl4 = &fl->u.ip4;
 136         __be32 daddr = fl4->daddr;
 137         __be32 saddr = fl4->saddr;
 138
 139         if (((saddr ^ r->src) & r->srcmask) ||
 140             ((daddr ^ r->dst) & r->dstmask))
 141                 return 0;
 142
 143         if (r->tos && (r->tos != fl4->flowi4_tos))
 144                 return 0;
 145
 146         return 1;
 147 }
 148
 149 static struct fib_table *fib_empty_table(struct net *net)
 150 {
 151         u32 id;
 152
 153         for (id = 1; id <= RT_TABLE_MAX; id++)
 154                 if (fib_get_table(net, id) == NULL)
 155                         return fib_new_table(net, id);
 156         return NULL;
 157 }
 158
 159 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 160         FRA_GENERIC_POLICY,
 161         [FRA_FLOW]      = { .type = NLA_U32 },
 162 };
 163
 164 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 165                                struct fib_rule_hdr *frh,
 166                                struct nlattr **tb)
 167 {
 168         struct net *net = sock_net(skb->sk);
 169         int err = -EINVAL;
 170         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 171
 172         if (frh->tos & ~IPTOS_TOS_MASK)
 173                 goto errout;
 174
 175         if (rule->table == RT_TABLE_UNSPEC) {
 176                 if (rule->action == FR_ACT_TO_TBL) {
 177                         struct fib_table *table;
 178
 179                         table = fib_empty_table(net);
 180                         if (table == NULL) {
 181                                 err = -ENOBUFS;
 182                                 goto errout;
 183                         }
 184
 185                         rule->table = table->tb_id;
 186                 }
 187         }
 188
 189         if (frh->src_len)
 190                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 191
 192         if (frh->dst_len)
 193                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 194
 195 #ifdef CONFIG_IP_ROUTE_CLASSID
 196         if (tb[FRA_FLOW]) {
 197                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 198                 if (rule4->tclassid)
 199                         net->ipv4.fib_num_tclassid_users++;
 200         }
 201 #endif
 202
 203         rule4->src_len = frh->src_len;
 204         rule4->srcmask = inet_make_mask(rule4->src_len);
 205         rule4->dst_len = frh->dst_len;
 206         rule4->dstmask = inet_make_mask(rule4->dst_len);
 207         rule4->tos = frh->tos;
 208
 209         net->ipv4.fib_has_custom_rules = true;
 210         err = 0;
 211 errout:
 212         return err;
 213 }
 214
 215 static void fib4_rule_delete(struct fib_rule *rule)
 216 {
 217         struct net *net = rule->fr_net;
 218 #ifdef CONFIG_IP_ROUTE_CLASSID
 219         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 220
 221         if (rule4->tclassid)
 222                 net->ipv4.fib_num_tclassid_users--;
 223 #endif
 224         net->ipv4.fib_has_custom_rules = true;
 225 }
 226
 227 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 228                              struct nlattr **tb)
 229 {
 230         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 231
 232         if (frh->src_len && (rule4->src_len != frh->src_len))
 233                 return 0;
 234
 235         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 236                 return 0;
 237
 238         if (frh->tos && (rule4->tos != frh->tos))
 239                 return 0;
 240
 241 #ifdef CONFIG_IP_ROUTE_CLASSID
 242         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 243                 return 0;
 244 #endif
 245
 246         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 247                 return 0;
 248
 249         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 250                 return 0;
 251
 252         return 1;
 253 }
 254
 255 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 256                           struct fib_rule_hdr *frh)
 257 {
 258         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 259
 260         frh->dst_len = rule4->dst_len;
 261         frh->src_len = rule4->src_len;
 262         frh->tos = rule4->tos;
 263
 264         if ((rule4->dst_len &&
 265              nla_put_be32(skb, FRA_DST, rule4->dst)) ||
 266             (rule4->src_len &&
 267              nla_put_be32(skb, FRA_SRC, rule4->src)))
 268                 goto nla_put_failure;
 269 #ifdef CONFIG_IP_ROUTE_CLASSID
 270         if (rule4->tclassid &&
 271             nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
 272                 goto nla_put_failure;
 273 #endif
 274         return 0;
 275
 276 nla_put_failure:
 277         return -ENOBUFS;
 278 }
 279
 280 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 281 {
 282         return nla_total_size(4) /* dst */
 283                + nla_total_size(4) /* src */
 284                + nla_total_size(4); /* flow */
 285 }
 286
 287 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 288 {
 289         rt_cache_flush(ops->fro_net);
 290 }
 291
 292 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
 293         .family         = AF_INET,
 294         .rule_size      = sizeof(struct fib4_rule),
 295         .addr_size      = sizeof(u32),
 296         .action         = fib4_rule_action,
 297         .suppress       = fib4_rule_suppress,
 298         .match          = fib4_rule_match,
 299         .configure      = fib4_rule_configure,
 300         .delete         = fib4_rule_delete,
 301         .compare        = fib4_rule_compare,
 302         .fill           = fib4_rule_fill,
 303         .default_pref   = fib_default_rule_pref,
 304         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 305         .flush_cache    = fib4_rule_flush_cache,
 306         .nlgroup        = RTNLGRP_IPV4_RULE,
 307         .policy         = fib4_rule_policy,
 308         .owner          = THIS_MODULE,
 309 };
 310
 311 static int fib_default_rules_init(struct fib_rules_ops *ops)
 312 {
 313         int err;
 314
 315         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 316         if (err < 0)
 317                 return err;
 318         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 319         if (err < 0)
 320                 return err;
 321         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 322         if (err < 0)
 323                 return err;
 324         return 0;
 325 }
 326
 327 int __net_init fib4_rules_init(struct net *net)
 328 {
 329         int err;
 330         struct fib_rules_ops *ops;
 331
 332         ops = fib_rules_register(&fib4_rules_ops_template, net);
 333         if (IS_ERR(ops))
 334                 return PTR_ERR(ops);
 335
 336         err = fib_default_rules_init(ops);
 337         if (err < 0)
 338                 goto fail;
 339         net->ipv4.rules_ops = ops;
 340         net->ipv4.fib_has_custom_rules = false;
 341         return 0;
 342
 343 fail:
 344         /* also cleans all rules already added */
 345         fib_rules_unregister(ops);
 346         return err;
 347 }
 348
 349 void __net_exit fib4_rules_exit(struct net *net)
 350 {
 351         fib_rules_unregister(net->ipv4.rules_ops);
 352 }