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 static struct fib_rules_ops fib4_rules_ops;
  36
  37 struct fib4_rule
  38 {
  39         struct fib_rule         common;
  40         u8                      dst_len;
  41         u8                      src_len;
  42         u8                      tos;
  43         __be32                  src;
  44         __be32                  srcmask;
  45         __be32                  dst;
  46         __be32                  dstmask;
  47 #ifdef CONFIG_NET_CLS_ROUTE
  48         u32                     tclassid;
  49 #endif
  50 };
  51
  52 static struct fib4_rule default_rule = {
  53         .common = {
  54                 .refcnt =       ATOMIC_INIT(2),
  55                 .pref =         0x7FFF,
  56                 .table =        RT_TABLE_DEFAULT,
  57                 .action =       FR_ACT_TO_TBL,
  58         },
  59 };
  60
  61 static struct fib4_rule main_rule = {
  62         .common = {
  63                 .refcnt =       ATOMIC_INIT(2),
  64                 .pref =         0x7FFE,
  65                 .table =        RT_TABLE_MAIN,
  66                 .action =       FR_ACT_TO_TBL,
  67         },
  68 };
  69
  70 static struct fib4_rule local_rule = {
  71         .common = {
  72                 .refcnt =       ATOMIC_INIT(2),
  73                 .table =        RT_TABLE_LOCAL,
  74                 .action =       FR_ACT_TO_TBL,
  75                 .flags =        FIB_RULE_PERMANENT,
  76         },
  77 };
  78
  79 #ifdef CONFIG_NET_CLS_ROUTE
  80 u32 fib_rules_tclass(struct fib_result *res)
  81 {
  82         return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
  83 }
  84 #endif
  85
  86 int fib_lookup(struct flowi *flp, struct fib_result *res)
  87 {
  88         struct fib_lookup_arg arg = {
  89                 .result = res,
  90         };
  91         int err;
  92
  93         err = fib_rules_lookup(&fib4_rules_ops, flp, 0, &arg);
  94         res->r = arg.rule;
  95
  96         return err;
  97 }
  98
  99 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
 100                             int flags, struct fib_lookup_arg *arg)
 101 {
 102         int err = -EAGAIN;
 103         struct fib_table *tbl;
 104
 105         switch (rule->action) {
 106         case FR_ACT_TO_TBL:
 107                 break;
 108
 109         case FR_ACT_UNREACHABLE:
 110                 err = -ENETUNREACH;
 111                 goto errout;
 112
 113         case FR_ACT_PROHIBIT:
 114                 err = -EACCES;
 115                 goto errout;
 116
 117         case FR_ACT_BLACKHOLE:
 118         default:
 119                 err = -EINVAL;
 120                 goto errout;
 121         }
 122
 123         if ((tbl = fib_get_table(rule->table)) == NULL)
 124                 goto errout;
 125
 126         err = tbl->tb_lookup(tbl, flp, (struct fib_result *) arg->result);
 127         if (err > 0)
 128                 err = -EAGAIN;
 129 errout:
 130         return err;
 131 }
 132
 133
 134 void fib_select_default(const struct flowi *flp, struct fib_result *res)
 135 {
 136         if (res->r && res->r->action == FR_ACT_TO_TBL &&
 137             FIB_RES_GW(*res) && FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK) {
 138                 struct fib_table *tb;
 139                 if ((tb = fib_get_table(res->r->table)) != NULL)
 140                         tb->tb_select_default(tb, flp, res);
 141         }
 142 }
 143
 144 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 145 {
 146         struct fib4_rule *r = (struct fib4_rule *) rule;
 147         __be32 daddr = fl->fl4_dst;
 148         __be32 saddr = fl->fl4_src;
 149
 150         if (((saddr ^ r->src) & r->srcmask) ||
 151             ((daddr ^ r->dst) & r->dstmask))
 152                 return 0;
 153
 154         if (r->tos && (r->tos != fl->fl4_tos))
 155                 return 0;
 156
 157         return 1;
 158 }
 159
 160 static struct fib_table *fib_empty_table(void)
 161 {
 162         u32 id;
 163
 164         for (id = 1; id <= RT_TABLE_MAX; id++)
 165                 if (fib_get_table(id) == NULL)
 166                         return fib_new_table(id);
 167         return NULL;
 168 }
 169
 170 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 171         FRA_GENERIC_POLICY,
 172         [FRA_FLOW]      = { .type = NLA_U32 },
 173 };
 174
 175 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 176                                struct nlmsghdr *nlh, struct fib_rule_hdr *frh,
 177                                struct nlattr **tb)
 178 {
 179         int err = -EINVAL;
 180         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 181
 182         if (frh->tos & ~IPTOS_TOS_MASK)
 183                 goto errout;
 184
 185         if (rule->table == RT_TABLE_UNSPEC) {
 186                 if (rule->action == FR_ACT_TO_TBL) {
 187                         struct fib_table *table;
 188
 189                         table = fib_empty_table();
 190                         if (table == NULL) {
 191                                 err = -ENOBUFS;
 192                                 goto errout;
 193                         }
 194
 195                         rule->table = table->tb_id;
 196                 }
 197         }
 198
 199         if (frh->src_len)
 200                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 201
 202         if (frh->dst_len)
 203                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 204
 205 #ifdef CONFIG_NET_CLS_ROUTE
 206         if (tb[FRA_FLOW])
 207                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 208 #endif
 209
 210         rule4->src_len = frh->src_len;
 211         rule4->srcmask = inet_make_mask(rule4->src_len);
 212         rule4->dst_len = frh->dst_len;
 213         rule4->dstmask = inet_make_mask(rule4->dst_len);
 214         rule4->tos = frh->tos;
 215
 216         err = 0;
 217 errout:
 218         return err;
 219 }
 220
 221 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 222                              struct nlattr **tb)
 223 {
 224         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 225
 226         if (frh->src_len && (rule4->src_len != frh->src_len))
 227                 return 0;
 228
 229         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 230                 return 0;
 231
 232         if (frh->tos && (rule4->tos != frh->tos))
 233                 return 0;
 234
 235 #ifdef CONFIG_NET_CLS_ROUTE
 236         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 237                 return 0;
 238 #endif
 239
 240         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 241                 return 0;
 242
 243         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 244                 return 0;
 245
 246         return 1;
 247 }
 248
 249 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 250                           struct nlmsghdr *nlh, struct fib_rule_hdr *frh)
 251 {
 252         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 253
 254         frh->family = AF_INET;
 255         frh->dst_len = rule4->dst_len;
 256         frh->src_len = rule4->src_len;
 257         frh->tos = rule4->tos;
 258
 259         if (rule4->dst_len)
 260                 NLA_PUT_BE32(skb, FRA_DST, rule4->dst);
 261
 262         if (rule4->src_len)
 263                 NLA_PUT_BE32(skb, FRA_SRC, rule4->src);
 264
 265 #ifdef CONFIG_NET_CLS_ROUTE
 266         if (rule4->tclassid)
 267                 NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
 268 #endif
 269         return 0;
 270
 271 nla_put_failure:
 272         return -ENOBUFS;
 273 }
 274
 275 static u32 fib4_rule_default_pref(void)
 276 {
 277         struct list_head *pos;
 278         struct fib_rule *rule;
 279
 280         if (!list_empty(&fib4_rules_ops.rules_list)) {
 281                 pos = fib4_rules_ops.rules_list.next;
 282                 if (pos->next != &fib4_rules_ops.rules_list) {
 283                         rule = list_entry(pos->next, struct fib_rule, list);
 284                         if (rule->pref)
 285                                 return rule->pref - 1;
 286                 }
 287         }
 288
 289         return 0;
 290 }
 291
 292 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 293 {
 294         return nla_total_size(4) /* dst */
 295                + nla_total_size(4) /* src */
 296                + nla_total_size(4); /* flow */
 297 }
 298
 299 static void fib4_rule_flush_cache(void)
 300 {
 301         rt_cache_flush(-1);
 302 }
 303
 304 static struct fib_rules_ops fib4_rules_ops = {
 305         .family         = AF_INET,
 306         .rule_size      = sizeof(struct fib4_rule),
 307         .addr_size      = sizeof(u32),
 308         .action         = fib4_rule_action,
 309         .match          = fib4_rule_match,
 310         .configure      = fib4_rule_configure,
 311         .compare        = fib4_rule_compare,
 312         .fill           = fib4_rule_fill,
 313         .default_pref   = fib4_rule_default_pref,
 314         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 315         .flush_cache    = fib4_rule_flush_cache,
 316         .nlgroup        = RTNLGRP_IPV4_RULE,
 317         .policy         = fib4_rule_policy,
 318         .rules_list     = LIST_HEAD_INIT(fib4_rules_ops.rules_list),
 319         .owner          = THIS_MODULE,
 320 };
 321
 322 void __init fib4_rules_init(void)
 323 {
 324         list_add_tail(&local_rule.common.list, &fib4_rules_ops.rules_list);
 325         list_add_tail(&main_rule.common.list, &fib4_rules_ops.rules_list);
 326         list_add_tail(&default_rule.common.list, &fib4_rules_ops.rules_list);
 327
 328         fib_rules_register(&fib4_rules_ops);
 329 }