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 static LIST_HEAD(fib4_rules);
  80
  81 #ifdef CONFIG_NET_CLS_ROUTE
  82 u32 fib_rules_tclass(struct fib_result *res)
  83 {
  84         return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
  85 }
  86 #endif
  87
  88 int fib_lookup(struct flowi *flp, struct fib_result *res)
  89 {
  90         struct fib_lookup_arg arg = {
  91                 .result = res,
  92         };
  93         int err;
  94
  95         err = fib_rules_lookup(&fib4_rules_ops, flp, 0, &arg);
  96         res->r = arg.rule;
  97
  98         return err;
  99 }
 100
 101 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
 102                             int flags, struct fib_lookup_arg *arg)
 103 {
 104         int err = -EAGAIN;
 105         struct fib_table *tbl;
 106
 107         switch (rule->action) {
 108         case FR_ACT_TO_TBL:
 109                 break;
 110
 111         case FR_ACT_UNREACHABLE:
 112                 err = -ENETUNREACH;
 113                 goto errout;
 114
 115         case FR_ACT_PROHIBIT:
 116                 err = -EACCES;
 117                 goto errout;
 118
 119         case FR_ACT_BLACKHOLE:
 120         default:
 121                 err = -EINVAL;
 122                 goto errout;
 123         }
 124
 125         if ((tbl = fib_get_table(rule->table)) == NULL)
 126                 goto errout;
 127
 128         err = tbl->tb_lookup(tbl, flp, (struct fib_result *) arg->result);
 129         if (err > 0)
 130                 err = -EAGAIN;
 131 errout:
 132         return err;
 133 }
 134
 135
 136 void fib_select_default(const struct flowi *flp, struct fib_result *res)
 137 {
 138         if (res->r && res->r->action == FR_ACT_TO_TBL &&
 139             FIB_RES_GW(*res) && FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK) {
 140                 struct fib_table *tb;
 141                 if ((tb = fib_get_table(res->r->table)) != NULL)
 142                         tb->tb_select_default(tb, flp, res);
 143         }
 144 }
 145
 146 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 147 {
 148         struct fib4_rule *r = (struct fib4_rule *) rule;
 149         __be32 daddr = fl->fl4_dst;
 150         __be32 saddr = fl->fl4_src;
 151
 152         if (((saddr ^ r->src) & r->srcmask) ||
 153             ((daddr ^ r->dst) & r->dstmask))
 154                 return 0;
 155
 156         if (r->tos && (r->tos != fl->fl4_tos))
 157                 return 0;
 158
 159         return 1;
 160 }
 161
 162 static struct fib_table *fib_empty_table(void)
 163 {
 164         u32 id;
 165
 166         for (id = 1; id <= RT_TABLE_MAX; id++)
 167                 if (fib_get_table(id) == NULL)
 168                         return fib_new_table(id);
 169         return NULL;
 170 }
 171
 172 static struct nla_policy fib4_rule_policy[FRA_MAX+1] __read_mostly = {
 173         FRA_GENERIC_POLICY,
 174         [FRA_SRC]       = { .type = NLA_U32 },
 175         [FRA_DST]       = { .type = NLA_U32 },
 176         [FRA_FLOW]      = { .type = NLA_U32 },
 177 };
 178
 179 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 180                                struct nlmsghdr *nlh, struct fib_rule_hdr *frh,
 181                                struct nlattr **tb)
 182 {
 183         int err = -EINVAL;
 184         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 185
 186         if (frh->src_len > 32 || frh->dst_len > 32 ||
 187             (frh->tos & ~IPTOS_TOS_MASK))
 188                 goto errout;
 189
 190         if (rule->table == RT_TABLE_UNSPEC) {
 191                 if (rule->action == FR_ACT_TO_TBL) {
 192                         struct fib_table *table;
 193
 194                         table = fib_empty_table();
 195                         if (table == NULL) {
 196                                 err = -ENOBUFS;
 197                                 goto errout;
 198                         }
 199
 200                         rule->table = table->tb_id;
 201                 }
 202         }
 203
 204         if (tb[FRA_SRC])
 205                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 206
 207         if (tb[FRA_DST])
 208                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 209
 210 #ifdef CONFIG_NET_CLS_ROUTE
 211         if (tb[FRA_FLOW])
 212                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 213 #endif
 214
 215         rule4->src_len = frh->src_len;
 216         rule4->srcmask = inet_make_mask(rule4->src_len);
 217         rule4->dst_len = frh->dst_len;
 218         rule4->dstmask = inet_make_mask(rule4->dst_len);
 219         rule4->tos = frh->tos;
 220
 221         err = 0;
 222 errout:
 223         return err;
 224 }
 225
 226 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 227                              struct nlattr **tb)
 228 {
 229         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 230
 231         if (frh->src_len && (rule4->src_len != frh->src_len))
 232                 return 0;
 233
 234         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 235                 return 0;
 236
 237         if (frh->tos && (rule4->tos != frh->tos))
 238                 return 0;
 239
 240 #ifdef CONFIG_NET_CLS_ROUTE
 241         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 242                 return 0;
 243 #endif
 244
 245         if (tb[FRA_SRC] && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 246                 return 0;
 247
 248         if (tb[FRA_DST] && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 249                 return 0;
 250
 251         return 1;
 252 }
 253
 254 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 255                           struct nlmsghdr *nlh, struct fib_rule_hdr *frh)
 256 {
 257         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 258
 259         frh->family = AF_INET;
 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
 267         if (rule4->src_len)
 268                 NLA_PUT_BE32(skb, FRA_SRC, rule4->src);
 269
 270 #ifdef CONFIG_NET_CLS_ROUTE
 271         if (rule4->tclassid)
 272                 NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
 273 #endif
 274         return 0;
 275
 276 nla_put_failure:
 277         return -ENOBUFS;
 278 }
 279
 280 int fib4_rules_dump(struct sk_buff *skb, struct netlink_callback *cb)
 281 {
 282         return fib_rules_dump(skb, cb, AF_INET);
 283 }
 284
 285 static u32 fib4_rule_default_pref(void)
 286 {
 287         struct list_head *pos;
 288         struct fib_rule *rule;
 289
 290         if (!list_empty(&fib4_rules)) {
 291                 pos = fib4_rules.next;
 292                 if (pos->next != &fib4_rules) {
 293                         rule = list_entry(pos->next, struct fib_rule, list);
 294                         if (rule->pref)
 295                                 return rule->pref - 1;
 296                 }
 297         }
 298
 299         return 0;
 300 }
 301
 302 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 303 {
 304         return nla_total_size(4) /* dst */
 305                + nla_total_size(4) /* src */
 306                + nla_total_size(4); /* flow */
 307 }
 308
 309 static struct fib_rules_ops fib4_rules_ops = {
 310         .family         = AF_INET,
 311         .rule_size      = sizeof(struct fib4_rule),
 312         .action         = fib4_rule_action,
 313         .match          = fib4_rule_match,
 314         .configure      = fib4_rule_configure,
 315         .compare        = fib4_rule_compare,
 316         .fill           = fib4_rule_fill,
 317         .default_pref   = fib4_rule_default_pref,
 318         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 319         .nlgroup        = RTNLGRP_IPV4_RULE,
 320         .policy         = fib4_rule_policy,
 321         .rules_list     = &fib4_rules,
 322         .owner          = THIS_MODULE,
 323 };
 324
 325 void __init fib4_rules_init(void)
 326 {
 327         list_add_tail(&local_rule.common.list, &fib4_rules);
 328         list_add_tail(&main_rule.common.list, &fib4_rules);
 329         list_add_tail(&default_rule.common.list, &fib4_rules);
 330
 331         fib_rules_register(&fib4_rules_ops);
 332 }