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
  66         if (err == -ESRCH)
  67                 err = -ENETUNREACH;
  68
  69         return err;
  70 }
  71 EXPORT_SYMBOL_GPL(__fib_lookup);
  72
  73 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  74                             int flags, struct fib_lookup_arg *arg)
  75 {
  76         int err = -EAGAIN;
  77         struct fib_table *tbl;
  78
  79         switch (rule->action) {
  80         case FR_ACT_TO_TBL:
  81                 break;
  82
  83         case FR_ACT_UNREACHABLE:
  84                 err = -ENETUNREACH;
  85                 goto errout;
  86
  87         case FR_ACT_PROHIBIT:
  88                 err = -EACCES;
  89                 goto errout;
  90
  91         case FR_ACT_BLACKHOLE:
  92         default:
  93                 err = -EINVAL;
  94                 goto errout;
  95         }
  96
  97         tbl = fib_get_table(rule->fr_net, rule->table);
  98         if (!tbl)
  99                 goto errout;
 100
 101         err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
 102         if (err > 0)
 103                 err = -EAGAIN;
 104 errout:
 105         return err;
 106 }
 107
 108 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 109 {
 110         struct fib_result *result = (struct fib_result *) arg->result;
 111         struct net_device *dev = NULL;
 112
 113         if (result->fi)
 114                 dev = result->fi->fib_dev;
 115
 116         /* do not accept result if the route does
 117          * not meet the required prefix length
 118          */
 119         if (result->prefixlen <= rule->suppress_prefixlen)
 120                 goto suppress_route;
 121
 122         /* do not accept result if the route uses a device
 123          * belonging to a forbidden interface group
 124          */
 125         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 126                 goto suppress_route;
 127
 128         return false;
 129
 130 suppress_route:
 131         if (!(arg->flags & FIB_LOOKUP_NOREF))
 132                 fib_info_put(result->fi);
 133         return true;
 134 }
 135
 136 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 137 {
 138         struct fib4_rule *r = (struct fib4_rule *) rule;
 139         struct flowi4 *fl4 = &fl->u.ip4;
 140         __be32 daddr = fl4->daddr;
 141         __be32 saddr = fl4->saddr;
 142
 143         if (((saddr ^ r->src) & r->srcmask) ||
 144             ((daddr ^ r->dst) & r->dstmask))
 145                 return 0;
 146
 147         if (r->tos && (r->tos != fl4->flowi4_tos))
 148                 return 0;
 149
 150         return 1;
 151 }
 152
 153 static struct fib_table *fib_empty_table(struct net *net)
 154 {
 155         u32 id;
 156
 157         for (id = 1; id <= RT_TABLE_MAX; id++)
 158                 if (fib_get_table(net, id) == NULL)
 159                         return fib_new_table(net, id);
 160         return NULL;
 161 }
 162
 163 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 164         FRA_GENERIC_POLICY,
 165         [FRA_FLOW]      = { .type = NLA_U32 },
 166 };
 167
 168 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 169                                struct fib_rule_hdr *frh,
 170                                struct nlattr **tb)
 171 {
 172         struct net *net = sock_net(skb->sk);
 173         int err = -EINVAL;
 174         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 175
 176         if (frh->tos & ~IPTOS_TOS_MASK)
 177                 goto errout;
 178
 179         if (rule->table == RT_TABLE_UNSPEC) {
 180                 if (rule->action == FR_ACT_TO_TBL) {
 181                         struct fib_table *table;
 182
 183                         table = fib_empty_table(net);
 184                         if (table == NULL) {
 185                                 err = -ENOBUFS;
 186                                 goto errout;
 187                         }
 188
 189                         rule->table = table->tb_id;
 190                 }
 191         }
 192
 193         if (frh->src_len)
 194                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 195
 196         if (frh->dst_len)
 197                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 198
 199 #ifdef CONFIG_IP_ROUTE_CLASSID
 200         if (tb[FRA_FLOW]) {
 201                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 202                 if (rule4->tclassid)
 203                         net->ipv4.fib_num_tclassid_users++;
 204         }
 205 #endif
 206
 207         rule4->src_len = frh->src_len;
 208         rule4->srcmask = inet_make_mask(rule4->src_len);
 209         rule4->dst_len = frh->dst_len;
 210         rule4->dstmask = inet_make_mask(rule4->dst_len);
 211         rule4->tos = frh->tos;
 212
 213         net->ipv4.fib_has_custom_rules = true;
 214         err = 0;
 215 errout:
 216         return err;
 217 }
 218
 219 static void fib4_rule_delete(struct fib_rule *rule)
 220 {
 221         struct net *net = rule->fr_net;
 222 #ifdef CONFIG_IP_ROUTE_CLASSID
 223         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 224
 225         if (rule4->tclassid)
 226                 net->ipv4.fib_num_tclassid_users--;
 227 #endif
 228         net->ipv4.fib_has_custom_rules = true;
 229 }
 230
 231 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 232                              struct nlattr **tb)
 233 {
 234         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 235
 236         if (frh->src_len && (rule4->src_len != frh->src_len))
 237                 return 0;
 238
 239         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 240                 return 0;
 241
 242         if (frh->tos && (rule4->tos != frh->tos))
 243                 return 0;
 244
 245 #ifdef CONFIG_IP_ROUTE_CLASSID
 246         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 247                 return 0;
 248 #endif
 249
 250         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 251                 return 0;
 252
 253         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 254                 return 0;
 255
 256         return 1;
 257 }
 258
 259 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 260                           struct fib_rule_hdr *frh)
 261 {
 262         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 263
 264         frh->dst_len = rule4->dst_len;
 265         frh->src_len = rule4->src_len;
 266         frh->tos = rule4->tos;
 267
 268         if ((rule4->dst_len &&
 269              nla_put_be32(skb, FRA_DST, rule4->dst)) ||
 270             (rule4->src_len &&
 271              nla_put_be32(skb, FRA_SRC, rule4->src)))
 272                 goto nla_put_failure;
 273 #ifdef CONFIG_IP_ROUTE_CLASSID
 274         if (rule4->tclassid &&
 275             nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
 276                 goto nla_put_failure;
 277 #endif
 278         return 0;
 279
 280 nla_put_failure:
 281         return -ENOBUFS;
 282 }
 283
 284 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 285 {
 286         return nla_total_size(4) /* dst */
 287                + nla_total_size(4) /* src */
 288                + nla_total_size(4); /* flow */
 289 }
 290
 291 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 292 {
 293         rt_cache_flush(ops->fro_net);
 294 }
 295
 296 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
 297         .family         = AF_INET,
 298         .rule_size      = sizeof(struct fib4_rule),
 299         .addr_size      = sizeof(u32),
 300         .action         = fib4_rule_action,
 301         .suppress       = fib4_rule_suppress,
 302         .match          = fib4_rule_match,
 303         .configure      = fib4_rule_configure,
 304         .delete         = fib4_rule_delete,
 305         .compare        = fib4_rule_compare,
 306         .fill           = fib4_rule_fill,
 307         .default_pref   = fib_default_rule_pref,
 308         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 309         .flush_cache    = fib4_rule_flush_cache,
 310         .nlgroup        = RTNLGRP_IPV4_RULE,
 311         .policy         = fib4_rule_policy,
 312         .owner          = THIS_MODULE,
 313 };
 314
 315 static int fib_default_rules_init(struct fib_rules_ops *ops)
 316 {
 317         int err;
 318
 319         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 320         if (err < 0)
 321                 return err;
 322         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 323         if (err < 0)
 324                 return err;
 325         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 326         if (err < 0)
 327                 return err;
 328         return 0;
 329 }
 330
 331 int __net_init fib4_rules_init(struct net *net)
 332 {
 333         int err;
 334         struct fib_rules_ops *ops;
 335
 336         ops = fib_rules_register(&fib4_rules_ops_template, net);
 337         if (IS_ERR(ops))
 338                 return PTR_ERR(ops);
 339
 340         err = fib_default_rules_init(ops);
 341         if (err < 0)
 342                 goto fail;
 343         net->ipv4.rules_ops = ops;
 344         net->ipv4.fib_has_custom_rules = false;
 345         return 0;
 346
 347 fail:
 348         /* also cleans all rules already added */
 349         fib_rules_unregister(ops);
 350         return err;
 351 }
 352
 353 void __net_exit fib4_rules_exit(struct net *net)
 354 {
 355         fib_rules_unregister(net->ipv4.rules_ops);
 356 }